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WO2025075929A1 - Methods of treating seizure activity - Google Patents

Methods of treating seizure activity Download PDF

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Publication number
WO2025075929A1
WO2025075929A1 PCT/US2024/049338 US2024049338W WO2025075929A1 WO 2025075929 A1 WO2025075929 A1 WO 2025075929A1 US 2024049338 W US2024049338 W US 2024049338W WO 2025075929 A1 WO2025075929 A1 WO 2025075929A1
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Prior art keywords
cells
subject
composition
mge
pallial
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PCT/US2024/049338
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French (fr)
Inventor
Cory R. NICHOLAS
Marina BERSHTEYN
Yves MAURY
Luis FUENTEALBA
Steven HAVLICEK
Sonja KRIKS
Seonok Lee
Mansi PAREKH
Sonja BRÖER
Andrew F. ADLER
David Blum
Gautam Banik
Catherine Priest
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Neurona Therapeutics Inc
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Neurona Therapeutics Inc
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Publication of WO2025075929A1 publication Critical patent/WO2025075929A1/en
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K35/00—Medicinal preparations containing materials or reaction products thereof with undetermined constitution
    • A61K35/12—Materials from mammals; Compositions comprising non-specified tissues or cells; Compositions comprising non-embryonic stem cells; Genetically modified cells
    • A61K35/30—Nerves; Brain; Eyes; Corneal cells; Cerebrospinal fluid; Neuronal stem cells; Neuronal precursor cells; Glial cells; Oligodendrocytes; Schwann cells; Astroglia; Astrocytes; Choroid plexus; Spinal cord tissue
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P25/00—Drugs for disorders of the nervous system

Definitions

  • MTLE Mesial temporal lobe epilepsy
  • SUMMARY [0004] Provided herein are methods of treating seizure activity, comprising: identifying a subject in need of treating seizure activity; and administering to the subject a therapeutically effective amount of a cellular composition comprising pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells.
  • a cellular composition comprising pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells.
  • 90% or more of the cells of the cellular composition are post-mitotic cells.
  • the cellular composition includes pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells, where at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1.
  • the cells of the cellular composition are substantially all pallial interneurons (e.g., are, are about, or are at least 90, 91, 92, 93, 94, 95, 96, 97, 98, 99%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 90-100%, 90-98%, 92-95%, 92-97%, etc.) pallial interneurons).
  • a frequency of seizures may be reduced after the administering, thereby treating the seizure activity.
  • a cellular composition for the treatment of seizure activity in a subject comprising pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells.
  • pluripotent stem cell-derived, MGE-type inhibitory e.g., GABAergic
  • at least 90% of the cells of the composition are post-mitotic cells.
  • the cellular composition includes pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1.
  • a cellular composition comprising pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells, for the preparation of a medicament for treatment of seizure activity in a subject.
  • pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells for the preparation of a medicament for treatment of seizure activity in a subject.
  • at least 90% of the cells of the cellular composition are post-mitotic cells.
  • the cellular composition includes, or are enriched for, pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1.
  • compositions of pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells are provided herein.
  • at least 90% of the cells of the composition are post-mitotic cells.
  • the therapeutic composition includes pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1.
  • the composition may be used for the treatment of a focal onset seizure.
  • compositions comprising: a poloxamer; and pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells at a concentration of about 1 x 10 5 cells/ ⁇ L or greater.
  • the therapeutic composition includes pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells.
  • a therapeutic composition for administering to a subject comprising: providing pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells; and preparing a composition comprising: a poloxamer; and the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells at a concentration of about 1 x 10 5 cells/ ⁇ L or greater.
  • the cellular composition includes pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells.
  • a cellular composition of the present disclosure includes pluripotent stem cell-derived, subpallial, MGE-type GABAergic neuron cells, wherein at least 50% of the cells of the composition express LHX6, LHX8 or NKX2.1, and GAD1.
  • the composition is depleted for cells expressing ERBB4 or MAF/MAFB.
  • the subpallial, MGE-type GABAergic neuron cells include interneurons and/or projection neurons.
  • a delivery cannula that includes: a proximal portion comprising a cellular liquid composition comprising cells at a concentration of about 1 x 10 5 cells/ ⁇ L or greater; and a distal portion comprising a cell-free liquid chase vehicle, wherein the cellular liquid composition is stably held in the proximal portion by the liquid chase vehicle; and a displacement device connected to the distal end of the cannula and configured to cause the liquid chase vehicle to displace the cellular liquid composition to thereby expel the cellular liquid composition from the proximal end of the cannula.
  • FIGs. 1A and 1B are flow diagrams showing a method of treating a focal onset seizure, according to some non-limiting embodiments of the present disclosure. [0014] FIGs.
  • FIG. 2A-2G show post thaw in vitro characterization of end-of-process cells derived from human embryonic stem cells (hESCs), according to some non-limiting embodiments of the present disclosure.
  • FIG. 2A is a schematic diagram showing neuronal subtypes derived from the MGE progenitor domain.
  • FIGs. 2B and 2C are a collection of images showing ICC staining of the hESC-derived cells with pallial MGE and cholinergic markers.
  • FIG. 2D is a graph showing marker expression profile of the hESC-derived cells, according to some non-limiting embodiments of the present disclosure, as determined by immunocytochemistry (ICC) analysis.
  • ICC immunocytochemistry
  • FIG. 2E is a graph showing GABA release from hESC-derived pallial MGE-type interneuron lots, undifferentiated hESCs and spinal motor neuron cultures.
  • FIG. 2F is a graph showing acetylcholine release from hESC-derived pallial MGE-type interneuron lots, undifferentiated hESCs and spinal motor neuron cultures.
  • FIG. 2G is a graph showing quantification of live cells in unsorted/sorted cell lots after cryopreservation and thaw.
  • FIGs. 3A-3G show single cell RNA sequencing characterization of cell composition during in vitro differentiation, according to some non-limiting embodiments of the present disclosure.
  • FIG. 3A-3G show single cell RNA sequencing characterization of cell composition during in vitro differentiation, according to some non-limiting embodiments of the present disclosure.
  • FIG. 3A is a plot showing UMAP (Uniform Manifold Approximation and Projection) visualization of cell clusters from samples combined.
  • FIG. 3B is a collection of plots showing UMAP visualization of cell clusters from samples separately.
  • FIG. 3C is a graph showing sample composition by cluster.
  • FIG. 3D is a collection of plots visualizing gene expression across different clusters.
  • FIG. 3E is a dot plot visualizing expression of key genes that define different cell categories.
  • FIG. 3F is a dot plot showing projection of prediction scores between 0 and 1 onto day 14 and end-of-process clusters.
  • FIG. 3G is a heatmap showing percentage of cells in each in vitro cluster that are assigned to different GE categories based on prediction scores.
  • FIGs.4A-4W show electrophysiological characterization of grafted human interneurons in the rodent pallium, according to some non-limiting embodiments of the present disclosure.
  • FIG. 4A is a collection of fluorescence microscopy images showing examples of grafted cell morphologies.
  • FIG. 4B is a collection of fluorescence microscopy images showing expression of human- and pallial interneuron specific markers.
  • FIG. 4C is a collection of fluorescence microscopy images showing HNA staining of recorded human cells in cortical slices.
  • FIGs. 4D and 4E are electrophysiology traces showing action potential recorded from transplanted human interneurons.
  • FIGS. 4F-4M are graphs showing physiological properties of grafted human cells.
  • FIG. 4A is a collection of fluorescence microscopy images showing examples of grafted cell morphologies.
  • FIG. 4B is a collection of fluorescence microscopy images showing expression of human- and pallial interneuron specific markers
  • FIG. 4N is a collection of traces showing current recordings before and after treatment with NBQX.
  • FIGs. 4O-4Q are graphs showing properties of glutamate–mediated spontaneous excitatory postsynaptic currents (sEPSCs) in transplanted human interneurons.
  • FIGs. 4R and 4S are electrophysiology traces showing examples of human interneurons firing evoked APs.
  • FIG. 4T is a collection of fluorescence microscopy images showing IHC staining of SYN-ChR2-YFP labeled human interneurons.
  • FIGs. 4U-4W are graphs showing properties of sEPSCs in transplanted human interneurons.
  • FIG. 4X is an electrophysiology trace showing recorded currents in light-stimulated ChR2- expressing human interneurons.
  • FIG. 4Y is an electrophysiology trace showing recorded currents in endogenous mouse neurons after light stimulation of the human interneurons.
  • FIG. 4Z is a graph showing the amplitude of light-evoked inhibitory postsynaptic currents in mouse neurons.
  • FIGs. 5A-5H show an overview of the chronic MTLE mouse model and seizure suppression after cell transplantation.
  • FIG. 5A is a schematic diagram showing the experimental timeline.
  • FIGs. 5B and 5C are a collection of EEG traces at various time points post-transplant.
  • FIG. 5D is a graph showing electrographic mesiotemporal seizure frequency for epileptic animals treated with hESC-derived interneurons.
  • FIG. 5E is a graph showing cumulative duration of seizures for epileptic animals treated with hESC-derived interneurons.
  • FIG. 5F is a graph showing electrographic mesiotemporal seizure frequency for epileptic animals treated with hESC-derived interneurons.
  • FIG. 5G is a fluorescence microscopy image showing staining of the hippocampus for markers for human cells and interneurons.
  • FIG. 5H is a fluorescence microscopy image showing staining of the hippocampus for markers for human cells and neurons.
  • FIGS. 6A-6G show histological characterization of interneuron in the epileptic hippocampus.
  • FIG. 6A is a collection of fluorescence microscopy images showing staining for markers of immature neurons and human cells.
  • FIG. 6B is a collection of fluorescence microscopy images showing staining for markers of MGE interneurons and human cells.
  • FIG. 6C is a collection of fluorescence microscopy images showing staining for a human-specific neuronal marker.
  • FIG. 6D is a collection of fluorescence microscopy images showing staining for a human housekeeping gene and GABAergic neuronal marker.
  • FIG. 6E is a collection of fluorescence microscopy images showing staining for human cells, MGE interneuron markers, and a perineuronal net marker, as well as lack of expression of off-target markers.
  • FIG. 6F is a graph showing the rate of persistence of human cells.
  • FIG. 6G is graph showing marker expression in persisting human cells. [0019] FIGs.
  • FIG. 7A-7J show human interneuron dose-response activity in the MTLE model, according to some non-limiting embodiments of the present disclosure.
  • FIG. 7A is a graph showing seizure frequency in epileptic animals treated with different doses of hESC- derived MGE-type pallial interneurons, according to some non-limiting embodiments of the present disclosure.
  • FIG. 7B is a collection of images showing immunohistochemical staining of the hippocampus for HNA and DAPI.
  • FIG. 7C is a collection of images showing immunohistochemical staining of the hippocampus for HNA and LHX6.
  • FIG. 7D is a collection of images showing immunohistochemical staining of the hippocampus for HNA and SST.
  • FIGs. 7E-7J show quantification of human cell persistence and fate.
  • FIGs. 7E and 7H are graphs showing, respectively, the total number of persisting human cells at 8.5 MPT and rate of persistence as a percentage of the initial dose.
  • FIGs. 7F and 7I are graphs showing quantification of the total number of LHX6 positive human cells and the percentage of human cells expressing LHX6, respectively.
  • FIGs. 7G and 7J are graphs showing the total number of SST positive human cells and the percentage human cells expressing SST, respectively.
  • FIGs. 8A-8Q show epileptic hippocampal pathology, behavioral outcome and animal survival after human interneuron transplantation, according to some non-limiting embodiments of the present disclosure.
  • FIG. 8A-8Q show epileptic hippocampal pathology, behavioral outcome and animal survival after human interneuron transplantation, according to some non-limiting embodiments of the present disclosure.
  • FIG. 8A-8Q show epileptic hippocampal pathology, behavioral outcome and animal survival after human
  • FIG. 8A is an image showing DAPI labeling of the granule cell (GC) layer in a na ⁇ ve animal.
  • FIG. 8B is an image showing DAPI labeling of the GC layer in an epileptic animal treated with vehicle.
  • FIGs. 8C, 8D, 8E, and 8F are each an image showing DAPI labeling of the GC layer in an epileptic animal treated with the indicated dose of hESC-derived interneurons (per hippocampus).
  • FIGs. 8G and 8H are graphs showing measurements of the GCL width and area, respectively.
  • FIGs. 8I and 8J are images showing immunohistochemical staining of the hippocampus for caspase3 with NEUN and HNA.
  • FIG. 8K and 8L are images showing immunohistochemical staining of the hippocampus for calbindin and HNA.
  • FIG. 8M is a collection of bar graphs showing results of a modified Irwin screen.
  • FIG. 8N is a collection of bar graphs showing open field test results.
  • FIG. 8O is a bar graph showing Y maze results.
  • FIG. 8P is a bar graph showing Barnes Maze results.
  • FIG. 8Q is survival curve for epileptic animals treated with either vehicle, or transplanted with cells.
  • FIGs. 9A-9G show in vitro characterization of hESC-derived VZ-like MGE progenitors after the two-week patterning phase, according to some non-limiting embodiments of the present disclosure.
  • FIG. 9A-9G show in vitro characterization of hESC-derived VZ-like MGE progenitors after the two-week patterning phase, according to some non-limiting embodiments of the present disclosure.
  • FIG. 9A-9G show in vitr
  • FIG. 9A is a collection of images showing FOXG1 expression in hESC-derived MGE-like progenitors by ICC (middle and bottom panels) and in the developing mouse brain at E13.5 by in situ hybridization (top panel).
  • FIG. 9B is a collection of images showing NKX2-1 expression in hESC-derived MGE-like progenitors by ICC (middle and bottom panels) and in the developing mouse brain at E13.5 by in situ hybridization (top panel).
  • FIG. 9C is a collection of images showing OTX-2 expression in hESC-derived MGE-like progenitors by ICC (middle and bottom panels) and in the developing mouse brain at E13.5 by in situ hybridization (top panel).
  • FIG. 9A is a collection of images showing FOXG1 expression in hESC-derived MGE-like progenitors by ICC (middle and bottom panels) and in the developing mouse brain at E13.5 by in situ hybridization (top panel).
  • FIG. 9B is
  • FIG. 9D is a collection of images showing LHX6 staining in hESC-derived MGE-like progenitors by ICC (bottom panel) and in the developing mouse brain at E13.5 by in situ hybridization (top panel).
  • FIG. 9E is a collection of images showing PAX6 staining in hESC-derived MGE-like progenitors by ICC (bottom panel) and in the developing mouse brain at E13.5 by in situ hybridization (top panel).
  • FIG. 9F is a collection of images showing NKX2-2 staining in hESC-derived MGE-like progenitors by ICC (bottom panel) and in the developing mouse brain at E13.5 by in situ hybridization (top panel).
  • FIG. 10G is a graph quantifying expression of different markers in hESC-derived MGE-like progenitors across different lots.
  • FIG. 9H is a graph quantifying expression of different markers in hESC-derived MGE-like progenitors in lots 1 and 2.
  • FIGs. 10A-10J show efficient and reproducible hESC differentiation into MGE-type pallial interneurons, according to some non-limiting embodiments of the present disclosure.
  • FIG. 10A is a schematic showing MGE pallial-type interneuron differentiation from hESCs and key markers used to characterize each stage.
  • FIG. 10B is a collection of images showing expression of the indicated markers by ICC at different time points.
  • FIG. 10C is a graph quantifying expression of the indicated markers over the different time points.
  • FIG. 10A is a schematic showing MGE pallial-type interneuron differentiation from hESCs and key markers used to characterize each stage.
  • FIG. 10B is a collection of images showing expression of the indicated markers
  • FIG. 10D is a collection of images showing expression of the indicated markers by ICC at different time points.
  • FIG. 10E is a graph quantifying expression of the indicated markers over the different time points.
  • FIG. 10F is a collection of images showing expression of the indicated markers by ICC at different time points.
  • FIG. 10G is a graph quantifying expression of the indicated markers over the different time points.
  • FIG. 10H is a graph showing the percentage of cells staining positive for the indicated markers, with or without MEK pathway inhibition.
  • FIGs. 10I and 10J are a collection of images showing LHX8 expression in end-of-process pallial interneuron, with or without MEK pathway inhibition. [0023] FIGs.
  • FIG. 11A-11E show that no residual proliferative progenitors or pluripotent stem cells were identified in the end-of-process (week 6) samples, according to some non-limiting embodiments of the present disclosure.
  • FIG. 11A is a graph quantifying Ki67 staining of cells derived from hESC with or without NOTCH and CDK pathway inhibition.
  • FIG. 11B is a graph quantifying 5-ethynyl-2’-deoxyuridine (EdU) staining of cells derived from hESC with or without NOTCH and CDK pathway inhibition.
  • FIG. 11C is a collection of images showing Edu staining in cells derived from hESC with (bottom panels) or without (top panels) NOTCH and CDK pathway inhibition.
  • FIG. 11A is a graph quantifying Ki67 staining of cells derived from hESC with or without NOTCH and CDK pathway inhibition.
  • FIG. 11B is a graph quantifying 5-ethynyl-2’-deoxyuridine (EdU)
  • FIG. 11D is a collection of images showing Ki67 staining in cells derived from hESC with or without NOTCH and CDK pathway inhibition.
  • FIGs. 11E and 11F are graphs quantifying expression of the indicated markers in cells derived from hESC with or without NOTCH and CDK pathway inhibition.
  • FIGs. 11G-11I are a collection of flow cytometry plots showing distribution of cells expressing the indicated pluripotency markers for in-process (Week 4, FIG. 11G) and end-of- process (FIG. 11H) samples.
  • FIG. 11I is a table showing the limits of detection (LOD) for residual TRA-1-60+/OCT4+ cells for in-process and end-of-process samples. [0024] FIGs.
  • FIG. 12A-12E show in vitro migration phenotypes of hESC-derived pallial MGE-type interneurons, according to some non-limiting embodiments of the present disclosure, compared to human endogenous MGE interneurons and commercially available hPSC-derived GABAergic cells.
  • FIG. 12A is a collection of phase contrast images showing a cell aggregate before (left most panel) and after 3 days of migration (remaining panels).
  • FIG. 12B is a collection of images showing staining for LHX6, MAFB, and ERBB4 by immunocytochemistry (ICC).
  • FIG. 12C is a graph quantifying percent migrating cells after 3 days.
  • FIG. 12A is a collection of phase contrast images showing a cell aggregate before (left most panel) and after 3 days of migration (remaining panels).
  • FIG. 12B is a collection of images showing staining for LHX6, MAFB, and ERBB4 by immunocytochemistry (ICC).
  • FIG. 12C is a graph quantifying
  • FIG. 12D is a collection of images comparing marker expression in hESC-derived pallial GABAergic MGE-type interneurons, according to some non-limiting embodiments of the present disclosure, and two commercial sources of hPSC-derived GABAergic neurons.
  • FIG. 12E is a table comparing qualitative analysis of marker expression in pallial GABAergic interneurons derived from hESC, according to some non-limiting embodiments of the present disclosure, and two commercial sources of hPSC-derived GABAergic neurons.
  • FIGs. 13A-13C show single cell RNA sequencing gene expression patterns in vitro and in the developing human GE.
  • FIG. 13A is a dot plot showing expression level of genes in each cluster.
  • FIGS. 14A-14H show reproducible seizure suppression achieved with additional independent cell production lots.
  • FIG. 14A is an image showing the right hippocampus and the kainate injection site (CA1).
  • FIG. 14B is a collection of images showing the right hippocampus overlayed with the sites of administration of the hESC- derived interneurons (dots) and the site of depth electrode implantation (arrow).
  • FIG. 14C is a graph showing seizure frequency based on EEG recordings made at the indicated time points.
  • FIG. 14A is an image showing the right hippocampus and the kainate injection site (CA1).
  • FIG. 14B is a collection of images showing the right hippocampus overlayed with the sites of administration of the hESC- derived interneurons (dots) and the site of depth electrode implantation (arrow).
  • FIG. 14C is a graph showing seizure frequency based on EEG recordings made at the indicated time points.
  • FIG. 14D and 14E are graphs showing seizure frequency and cumulative seizure duration based on EEG recordings made at the indicated time points.
  • FIG. 14F is a collection of images showing expression of SST and HNA in transplanted human cells.
  • FIG. 14G is a collection of images showing fluorescence in situ hybridization (FISH) staining of the distribution of transplanted human cells in the hippocampus.
  • FIG. 14H is a collection of images showing immunohistochemistry staining of transplanted human cells in the hippocampus.
  • FIG. 15 is a collection of graphs showing stability of cryopreserved hPSC- derived, pallial, MGE-type GABAergic interneurons after thawing. [0028] FIGs.
  • FIG. 16A and 16B are collection of graphs showing consistent delivery of hPSC-derived, pallial, MGE-type GABAergic interneurons held in a cannula configured to hold and deliver the cells, according to some non-limiting embodiments of the present disclosure.
  • FIG. 17 is a collection of schematics and plots showing stability of cells post-thaw and after a hold period in a cannula, according to some non-limiting embodiments of the present disclosure.
  • FIG. 18 is a collection of images showing migration potential of cells post-thaw and after a hold period in a cannula, according to some non-limiting embodiments of the present disclosure.
  • FIG. 19A-19I show molecular characterization of human pallial interneurons 1-18 months post transplantation (MPT) using single nuclei RNA sequencing (snRNAseq).
  • FIG. 19A is a plot showing UMAP (Uniform Manifold Approximation and Projection) visualization of cell clusters.
  • FIG. 19B is a collection of plots showing prediction scores of transplanted hESC-derived pallial interneuron (pIN) gene expression compared with endogenous human pINs from adult M1 cortex.
  • FIG. 19C is a collection of dot plots showing expression level of key genes that define different cell categories by the transplanted hESC-derived pINs.
  • FIG. 19D-19F are a collection of plots showing expression level of different genes across cells among the transplanted hESC-derived pINs.
  • FIG. 19G is a plot showing subclass categories of transplanted human cells based on prediction and cluster marker analyses.
  • FIG. 19H is a graph showing quantification of graft composition by subclass categories across 5 time points post-transplant.
  • FIG. 19I is plot showing projection of hESC-derived MGE pIN subclasses onto human prenatal-adult prefrontal cortex interneuron dataset.
  • FIG. 20 is a collection of graphs showing the effect of single-dose administration of NRTX-1001 in subjects with drug-resistant MTLE, according to some non- limiting embodiments of the present disclosure.
  • FIG. 20 is a collection of graphs showing the effect of single-dose administration of NRTX-1001 in subjects with drug-resistant MTLE, according to some non- limiting embodiments of the present disclosure.
  • FIG. 20 is a collection of graphs showing the effect of single-
  • FIG. 21 is a collection of graphs showing levels of metabolites in the hippocampus of a subject treated with NRTX-1001, according to some non-limiting embodiments of the present disclosure.
  • FIG. 22 depicts data showing the results of neurocognitive tests in subjects treated with NRTX-1001, according to some non-limiting embodiments of the present disclosure.
  • FIG. 23A is a collection of graphs showing the effect of transplanting hESC-derived interneurons on urethane-induced theta oscillations in a 5xFAD Alzheimer’s disease model.
  • FIG. 23B is a collection of graphs showing the effect of transplanting hESC-derived interneurons on 5xFAD AD mice treated with riluzole.
  • FIG. 24 is a schematic diagram showing a cell delivery system and use thereof, according to some non-limiting embodiments of the present disclosure.
  • FIGs. 25A-25N shows stable graft composition from 1 to 18 MPT comprised of PVALB and SST subclasses, according to some non-limiting embodiments of the present disclosure.
  • FIG. 25B shows integrated UMAP clustering of all the human cells across time points.
  • FIG. 25C shows feature plots of GABAergic (GAD1, GAD2) and MGE (LHX6, SOX6) markers.
  • FIG. 25D shows expression by cluster of genes that characterize different cell categories, including general markers of neurons, GABAergic and MGE neurons, preoptic area (POA), caudal and lateral GE (CGE/LGE), neuronal progenitors (NPC), cycling cells, ESC, as well as genes associated with glial cells, glutamatergic neurons (Glu), dopaminergic neurons (DA), serotonergic neurons (5HT) and cholinergic neurons (Ach).
  • FIG. 25E shows population prediction scores comparing transplanted cells with human adult brain superclusters corresponding to diverse cell types 42 .
  • FIG. 25F shows MGE interneuron prediction scores overlaid onto grafted cell UMAP.
  • FIG. 25G shows graft composition over time based on transcriptional similarity to adult brain superclusters.
  • FIG. 25H shows MGE- and CGE-derived interneuron subclass prediction scores overlaid onto grafted cell UMAP.
  • MGE- and CGE-derived interneuron subclass prediction scores overlaid onto grafted cell UMAP.
  • MGE- and CGE-derived interneuron subclass prediction scores overlaid onto grafted cell UMAP.
  • MGE- and CGE-derived interneuron subclass prediction scores overlaid onto grafted cell UMAP.
  • MGE- and CGE-derived interneuron subclass prediction scores overlaid onto grafted cell UMAP.
  • MGE- and CGE-derived interneuron subclass prediction scores overlaid onto grafted cell UMAP.
  • MGE- and CGE-derived interneuron subclass prediction scores overlaid onto grafted cell UMAP.
  • MGE- and CGE-derived interneuron subclass prediction scores overlaid onto grafted cell UMAP
  • FIG. 25N shows expression of subclass-enriched genes.
  • FIGs. 25G, 25K, 25L data shown are mean ⁇ SEM.
  • FIGs. 26A-26L show additional characterization of post-transplant cell identity.
  • FIG. 26A shows quality metrics of post-transplant cell clusters, including number of unique genes detected (nFeature), number of total RNA molecules (nCount), percentage of mitochondrial and ribosomal genes, according to some non-limiting embodiments of the present disclosure.
  • FIGs. 26B and 26C show UMAP colored by Age (FIG. 26B) and by batch ID (FIG. 26C).
  • FIG. 26D shows expression of key genes over time.
  • FIGs. 26E and 26F show prediction scores projected onto the integrated UMAPs based on comparisons to the listed human adult brain cell types (FIG. 26E) and brain regions (FIG. 26F) 42 .
  • the ridge plot on the right panel in FIG. 26F shows distribution of prediction scores for the transplanted population compared to each reference brain region.
  • FIG. 26G shows prediction scores projected onto the integrated UMAPs based on comparisons to endogenous human PVALB, SST and SST NPY subclasses, separated by age.
  • the ridge plots show distribution of prediction scores for each subclass over time compared to adult human MTG (middle panels) 48 and M1 cortex (right panels) 49 reference datasets.
  • FIG. 26H shows expression of several conserved markers (ERBB4, SLIT2, SHISA9, RUNX2) enriched in endogenous PVALB INs compared to SST INs in the adult human M1 cortex and mouse cortex + hippocampus (adapted from the Allen Brain Map: Cell Types Database).
  • FIGs. 26I-26L show grafted human cells analyzed by fluorescence in situ hybridization (FISH) using RNAscope probes against the GABAergic marker glutamate decarboxylase 1 (GAD1), PVALB-enriched marker SLIT2, SST and NPY to assess the main cell populations.
  • FISH fluorescence in situ hybridization
  • FIG. 26I shows MALAT1 was chosen as a FISH probe target to identify all human cells due to its strong and ubiquitous expression, regardless of subclass or MPT (99.99% of the cells are positive).
  • FIG. 26J shows expression of GAD1, SLIT2, SST, and NPY transcripts by subclass over time.
  • FIG. 26K shows representative FISH images showing expression of listed targets in transplanted human cells in the mouse cortex. Note that the GAD1 probe, although designed against human mRNA sequence, also binds to endogenous mouse GAD1.
  • FIG. 26L shows quantification of MALAT1+ cells co-expressing listed targets. Each dot is from a different hemisphere, after averaging technical replicates (4 sections each).
  • FIGs. 27A-27J show transplantation environment triggers expression of synaptic genes enabling rapid cell fate identification, according to some non-limiting embodiments of the present disclosure.
  • FIG. 27C shows alluvial plots showing transcriptomic relationship between pre- and post-transplant cell populations.
  • FIG. 27D shows graft composition by subclass at 14 DPT and 1 MPT.
  • FIGs. 27E and 27F show PVALB, SST and SST NPY prediction scores across samples shown as feature plots (FIG. 27E) and ridge plots (FIG. 27F).
  • FIG. 27G shows expression of cell-type- specific genes upregulated in 1 MPT vs 30 DIV samples.
  • FIGs. 27H-27J show evaluation of graft development post-transplantation compared with human cortical development spanning from prenatal to postnatal stages. The quantification is based on predicted cell stage analysis using cortical developmental datasets as a reference 51 .
  • FIG. 27D shows graft composition by subclass at 14 DPT and 1 MPT.
  • FIGs. 27E and 27F show PVALB, SST and SST NPY prediction scores across samples shown as feature plots (FIG.
  • FIG. 27H shows distribution of grafted cell maturation states over time on the top relative to broad human stages, corresponding to developmental changes in neuronal physiology shown on the bottom (adapted from 19 ).
  • FIG. 27I shows grafted cell maturation states over time separated by the three main subclasses.
  • FIG. 27J shows on the left, the re-clustering of endogenous human interneurons from prefrontal cortex, PFC (original dataset from 51 ) colored by age, with the CGE- and MGE-derived interneuron populations indicated. On the right, projection of grafted cells at different stages colored by subclass onto human PFC interneurons.
  • FIGs. 28A-28G show gene expression patterns under different conditions and at different stages post-transplant.
  • FIG. 28A and 28B show integrated clustering analysis of lot 010519S1 sequenced prior to transplantation (PRE cells and PRE nuclei), after 30 DIV (nuclei), 14 DPT (nuclei) and 1 MPT (nuclei), colored by cluster (FIG. 28A) and by subclass (FIG. 28B).
  • FIG. 28C shows expression of ERBB4 (enriched in PVALB subclass) and RELN (enriched in SST subclass) in PRE, 30 DIV and 1 MPT nuclei samples.
  • FIG. 28D shows GO term analysis for biological processes enriched in subclass-specific genes that are upregulated in 1 MPT vs 30 DIV samples.
  • FIGs. 28E-28G show GO term analysis for biological processes (FIG.
  • FIGs. 29A-29L show cell development is characterized by major transcriptional changes during the first 3 MPT followed by gradual unfolding of gene modules involved in regulation of synaptic transmission and membrane potential.
  • FIGs. 29A- 29C show clustering analysis of all the cells pooled together (without integration), colored by MPT (FIG. 29A), by subclass with all the stages combined (FIG. 29B), or separated by MPT (FIG. 29C).
  • FIG. 29D shows expression of neuronal, GABAergic and MGE markers across transcriptional states.
  • FIG. 29E shows stage-specific expression pattern corresponding to pre- transplant (PRE), 1 MPT and 3-18 MPT transcriptional states.
  • FIG. 29F shows gene networks of top 4 GO biological processes enriched at each of the main transcriptional states.
  • FIG. 29G shows identification of genes through DGE analysis that continue to be upregulated over time.
  • FIG. 29H shows GO term analysis for biological processes that are enriched after 3 MPT and 6 MPT.
  • FIGs. 29I and 29J show expression of gene modules that regulate chemical synaptic transmission (FIG. 29I) and membrane potential (FIG. 29J) in the grafts over time (top plots). In the bottom plots, expression of the same modules is plotted for 18 MPT grafts in the context of human cortical development.
  • FIGs. 29I chemical synaptic transmission
  • FIG. 29J membrane potential
  • FIGs. 30A-30G show hMGE-pIN grafts are comprised of multiple PVALB and SST subtypes, according to some non-limiting embodiments of the present disclosure.
  • FIG. 30A shows the cluster correlation to each other.
  • FIG. 30B shows the proportion of nuclei from the 18 MPT ESC-derived clusters (columns) that correspond to endogenous adult interneuron subtypes (rows) defined in the cell census atlas of the mammalian primary motor cortex 10 based on prediction analysis.
  • CGE- and MGE-derived interneuron subtypes Of the 72 transcriptionally defined CGE- and MGE-derived interneuron subtypes, only the ones which transplanted hMGE-pINs match by >10% are included in this heatmap.
  • human cluster cellular taxonomy classification is shown, based on mouse/human cross-species overlap analysis, where multimodal data (morphology, physiology and transcriptomics) were applied to define the mouse interneuron subtypes 10 .
  • FIG. 30C shows UMAP of all the transplanted cells, colored by transcriptionally distinct populations based on data-driven marker analyses, cluster correlations and overlap with human interneuron subtypes.
  • FIG. 30D shows graft composition by subtype over time. Bar graphs shown mean ⁇ SEM.
  • FIG. 30E shows top subtype markers.
  • FIG. 30F shows expression of transcription factors, sodium, calcium and potassium voltage gated ion channels and regulatory subunits, as well as cell adhesion molecules involved in cell recognition 43 , in pooled 12-18 MPT data across subtypes.
  • FIG. 30G shows expression of several voltage gated ion channels over time and across subtypes. [0044] FIGs.
  • FIG. 31A-31S shows grafted hMGE-pINs acquire histological features of known PVALB and SST subtypes, according to some non-limiting embodiments of the present disclosure.
  • FIG. 31A shows a diagram showing transplantation sites and dosing in the neonatal cortex for histological characterization.
  • FIG. 31B shows distribution of hMGE-pINs labeled with human-specific nuclear antigen (HNA), the immature neuronal marker DCX, and the MGE-lineage marker LHX6 at 1 MPT (coronal view).
  • FIG. 31C shows the percent of HNA+ cells persisting at 1, 4, and 17 MPT out of the number of cells that were injected.
  • HNA human-specific nuclear antigen
  • DCX the immature neuronal marker
  • LHX6 MGE-lineage marker
  • FIG. 31D shows the relative rostrocaudal distribution of HNA+ cells at 1 and 4 MPT.
  • FIG. 31F shows an example of hMGE-pIN with Martinotti morphology.
  • FIGs. 31G and 31H show human SST-positive cells co-expressing Martinotti markers CALB1 (FIG. 31G) and ETV1 (FIG. 31H).
  • FIG. 31I and 31J show human SST-positive cells co-expressing SST1 (predicted non-Martinotti subtype) cluster markers GULP1 (FIG. 31I) and NPAS3 (FIG. 31J).
  • FIG. 31G and 31H show human SST-positive cells co-expressing Martinotti markers CALB1 (FIG. 31G) and ETV1 (FIG. 31H).
  • FIG. 31I and 31J show human SST-positive cells co-expressing SST1 (predicted non-Martinotti subtype) cluster markers GULP1 (FIG. 31I) and NPAS3 (FIG. 31J).
  • FIG. 31K shows an example of a GFP-labeled long-range projection (LRP) neuron in layer VI with a long axonal collateral projecting parallel to the corpus callosum (inset shows SST+ expression in its soma and higher magnifications of the long projection).
  • FIGs. 31L and 31M show human cells with LRP characteristics frequently express SST, NPY, and NOS1.
  • FIG. 31N-31P show representative images of NPY+SST+ axonal projections, which are frequently found in the caudal hippocampus (medial DG-CA3 (FIG. 31N)), midline corpus callosum (FIG. 31O), and caudate putamen (next to the nucleus accumbens (FIG.
  • FIG. 31Q shows an example of a ERBB4+ (SST negative) hIN with basket cell features in layer IV.
  • FIG. 31R shows these cells form axonal arborizations (marked by human-specific SYP) around the somata of pyramidal neurons and interneurons.
  • FIG. 31S shows nuclear expression of the PV2 (predicted Basket subtype) cluster marker BCL6. Inset shows BCL6 nuclear expression and lack of SST expression. All images and quantifications were taken from animals at 7-15 MPT.
  • FIGs. 32A-32N’ show hMGE-pINs exhibit subclass-specific synaptic connectivity features in the host mouse cortex, according to some non-limiting embodiments of the present disclosure.
  • FIG. 32A-32B show increased cortical expression of the human-specific synaptophysin (SYP) in layers I-II (FIG. 32A) and IV (FIG. 32B) at 1, 7, and 13 MPT.
  • FIG. 32C show Diagram showing a pyramidal projection neuron with dendritic (Pex5L) and somatic (NeuN), as well as presynaptic (Gephyrin and GabaR1) marker expression. Postsynaptic and axonal markers associated with SST (green) and PVALB (red) subclasses are illustrated collocalizing with human-specific TAU and SYP.
  • FIG. 32D and 32E show examples of inhibitory synapses found in layer I composed of presynaptic human SYP and SST and postsynaptic Gephyrin (arrows).
  • FIG. 32F shows SST-expressing human axonal terminals are intimately intertwined with Pex5L+ distal dendrites of pyramidal cells (FIG. 32F’, 32F” show higher magnifications with SST expression).
  • FIG. 32G, 32G’ show representative images showing co-expression of human-specific SYP and synaptoporin (SYPR) in axonal terminals in layers I/II.
  • FIGs. 32H and 32I show examples of human axonal processes in layer I co-expressing SST, the glutamate ionotropic receptor, GRIN3A (FIG. 32H), and the SST1-cluster marker, ARHGAP6 (arrows in 32I; additional examples are shown in 32I’ and I”).
  • FIGs. 32J-32L show Human axonal terminals show perisomatic synaptic patterns associated with PVALB cells in layer IV. Examples of perisomatic synapses formed between presynaptic human SYP (FIG. 32J, 32K) and LGI2 (FIG. 32L), and host cell postsynaptic GabaR1 (arrows). Bottom panels (FIGs.
  • FIG. 32J’-32L correspond to additional examples for each marker combination at higher magnification.
  • NeuN labels neuronal cell bodies (FIG. 32K).
  • FIG. 32M and 32N show representative images showing perisomatic human axonal terminals co-expressing the PVALB-enriched potassium channels, KIR3.1 (encoded by KCNJ3) and KV3.2 (encoded by KCNC2) (FIG. 32M and 32N, respectively).
  • Insets (32M’ and 32N’) correspond to higher magnification of their respective images. Samples were obtained at 7-18 MPT.
  • FIGs. 33A-33D show stability of cells post-thaw and following a hold period in a cannula, according to some non-limiting embodiments of the present disclosure.
  • FIGs. 34A-34C show persistence, migration, and distribution of hPSC- derived GABAergic interneurons at 1 month-post-transplantation (1 MPT) into neonate P1-2 rodent brains, according to some non-limiting embodiments of the present disclosure. Results show that cell persistence (FIG. 34A), migration (FIG.
  • FIGs. 35A-35B show single-cell RNA sequencing analysis of hPSC- derived GABAergic interneurons after 1 month and 4 months post-transplantation, according to some non-limiting embodiments of the present disclosure. Transplantation into rodent brains revealed no off-target cell types, off-target gene expression, or significant differences in gene expression patterns (FIG. 35A). The gene expression profiles and composition were consistent between cells stored at 2-18°C for 48-72 hours and the overnight reference control, and were comparable between the 1-month and 4-month post-transplantation time points (FIG. 35B).
  • FIGs. 36A-36B show effects of neurotransmitter receptor antagonists on spontaneous calcium activity from in vitro human pallial interneuron (hpIN) cultures, according to some non-limiting embodiments of the present disclosure.
  • FIG. 36A shows calcium traces show activity of 30 neurons before (baseline) and after the addition of small molecule antagonists (dashed red line). After 17 days in vitro, samples were treated using control media (vehicle), two sets of two compounds (Picrotoxin + Saclofen or NBQX + AP- 5), or TTX, all diluted in vehicle media.
  • 36B shows fold change in firing rate after application of each set of compounds shows no significant changes in calcium activity before and after addition of vehicle (control media), picrotoxin and saclofen (GABAA and GABAB receptor antagonists, respectively), or NBQX and AP-5 (AMPA- and NMDA-receptor antagonists, respectively).
  • vehicle control media
  • picrotoxin and saclofen GABAA and GABAB receptor antagonists, respectively
  • NBQX and AP-5 AMPA- and NMDA-receptor antagonists, respectively.
  • TTX Na+ channel blocker
  • FIG. 37A-37T show multi-electrode array analysis of co-cultured hiPSC derived glutamatergic neurons, mouse primary astrocytes with or without human GABAergic pallial interneurons (hpIN) , according to some non-limiting embodiments of the present disclosure.
  • FIG. 37A shows representative immunostaining images demonstrating survival of glutamatergic neurons (EMX2, TBR1), astrocytes (GFAP) and interneurons (LHX6, SST) after 40 days of co-culture in vitro on the MEA plate (FIGs. 37B-37C).
  • EMX2, TBR1 glutamatergic neurons
  • GFAP astrocytes
  • LHX6, SST interneurons
  • FIG. 37D-37E shows analysis of synchrony index and mean firing rate for Bit.bio (ioGluta) iPSC-derived glutamatergic neurons with only primary mouse astrocytes (purple, BitBio Gluta alone) or with human pallial interneurons (red, BitBio Gluta + hpIN).
  • FIG. 37F-37K show connectivity (synchronicity) and neuron network dynamics (network) measurements for 24 days in vitro (DIV) (highlighted dashed box in FIGs. 37D-37E) show a clear difference +/- hpIN.
  • FIG. 37L shows ioGluta only cultures show no changes in neural acivity after the addition of the GABAA receptor antagonist, picrotoxin. However, ioGluta + hpIN show an obvious change in network activity after the addition of picrotoxin.
  • FIG. 37M shows PCA analysis revealing that ioGluta-only cultures cluster together before and after picrotoxin addition, while ioGluta + hpIN cultures cluster separately at baseline but move closer to ioGluta-only wells, post- picrotoxin treatment.
  • FIG. 37Q ioGluat+hpIN after a 20 minutes picrotoxin treatment.
  • FIG. 37R shows Louvain clustering analysis identified 6 main clusters in the UMAP representation of all network event properties.
  • FIG. 37S shows a specific color has been attributed to each cluster.
  • FIG. 37T shows quantification of network event distribution across the 6 identified clusters demonstrate ioGluta alone cultures show similar distribution of the network events before and after picrotoxin addition. However, ioGluta + hpIN clustering shows a very different distribution with a large portion of network events in cluster#2 not shared with ioGluta alone cultures.
  • FIGs. 38A-38B shows epileptic MTLE mouse model behavioral outcome after human pIN transplantation, according to some non-limiting embodiments of the present disclosure.
  • Open Field test (FIG. 38A, general anxiety, spatial locomotion and travel velocity) and Light-Dark Emergence (FIG. 38B, Anxiety). Also shown are percent of animals emerged and non-emerged.
  • FIGs. 39A-39E show an epileptic MTLE mouse model hippocampal pathology analysis showing that the progression of dentate granule cell dispersion from before transplant to 8.5 months post-human pIN transplantation is halted, with similar dispersion observed across time points post-transplant, according to some non-limiting embodiments of the present disclosure.
  • FIG. 39A shows granule cell dispersion analysis at 1 MPSE (age and time-matched to efficacy study mice at time of pIN transplantation.
  • FIG. 39A-39D show granule cell dispersion analysis at 8.5 MPT in age-matched mice: Prox1 labeling shows representative granule cell (GC) layer in early epileptic mice (FIG. 39A), naive mouse age-matched to end of study mice (FIG. 39B), epileptic cell-treated mice at end of study (FIG. 39C) and epileptic vehicle-treated mice at end of study (FIG. 39D).
  • FIG. 39E shows Average GC layer area. All data are mean ⁇ SEM. The Kruskal Wallis statistic, followed by Dunn’s test, was significant between all three groups at the end of the study (P ⁇ 0.05). GC area in epileptic mice at time of transplant was not significantly different from cell-treated mice at the end of study.
  • FIGs. 40A-40D show percent change from baseline in neurocognitive and quality of life test performance after low dose administration of NRTX-1001 to human MTLE subjects in the ongoing Phase 1/2 study, according to some non-limiting embodiments of the present disclosure.
  • FIG. 40B shows BVMT: Brief Visuospatial Memory Test delayed recall score.
  • FIG. 40C shows RAVLT: Ray Auditory Verbal Learning Test delayed recall score.
  • FIG. 40D shows QOLIE- 31P: Quality of Life total score. T-score measurements with reliable change index noted.
  • FIG. 40B shows BVMT: Brief Visuospatial Memory Test delayed recall score.
  • FIG. 40C shows RAVLT: Ray Auditory Verbal Learning Test delayed recall score.
  • FIG. 40D shows QOLIE- 31P: Quality of Life total score. T-score measurements with reliable change index noted.
  • FIG. 41A-41B show percent change from baseline in monthly seizure frequency after low dose administration of NRTX-1001 to human MTLE subjects in the ongoing Phase 1/2 study, according to some non-limiting embodiments of the present disclosure.
  • FIG. 41A shows all seizures plotted, including focal aware, impaired awareness, and focal to bilateral tonic clonic seizures.
  • FIG. 41B shows only disabling seizures plotted, including focal aware, impaired awareness, and focal to bilateral tonic clonic seizures as above but excluding aware seizures without objective manifestation (auras).
  • FIGs. 42A-42B show histological characterization of amyloid plaques in two Alzheimer’s disease (AD) mouse models: 5XFAD and TG2576, according to some non- limiting embodiments of the present disclosure.
  • FIG. 41A shows amyloid plaque deposits are observed in the cortex and hippocampus in two models of AD, TG2576 and 5XFAD at 21 and 16 months of age.
  • FIG. 41B shows higher magnification images of the amyloid plaques (cyan) surrounded by activated microglia marked by CD68 (red) in the TG2576 and 5XFAD models.
  • FIGs. 43A-43B show human interneuron transplantation in two mouse models of Alzheimer’s disease, according to some non-limiting embodiments of the present disclosure.
  • FIG. 43A shows images of human ESC-derived interneurons transplanted into the rostro-dorsal and caudal-ventral hippocampus of 5XFAD mice at 11 MPT.
  • the transplanted cells (marked by human-specific nuclear antigen (HNA) and the interneuron subtype marker, SST) persist and migrate throughout the hippocampus. In addition, the transplanted cells project extensively to surrounding areas as marked by the human-synaptophysin (SYP) marker.
  • FIG. 43B shows images of human ESC-derived interneurons transplanted into the rostro-dorsal and caudal-ventral hippocampus of TG1576 mice at 16 MPT.
  • the transplanted cells (marked by human-specific nuclear antigen (HNA) and the interneuron subtype marker, SST) persist and migrate throughout the hippocampus. In addition, the transplanted cells project extensively to surrounding areas as marked by the human-TAU marker.
  • FIGs. 44A-44B show human interneuron transplantation reduces the number of amyloid plaques in the TG2576 AD mouse model, according to some non-limiting embodiments of the present disclosure.
  • FIG. 44A shows quantification of plaque densities in the hippocampus at 3 different levels (rostral, middle and caudal) in vehicle-injected and human interneuron transplanted animals.
  • FIG. 44B shows the effect of human cell transplantation in the average plaque size in the hippocampus of TG2576 mice.
  • FIG. 45 shows human interneuron transplantation rescues animal survival in the TG2576 AD mouse model, according to some non-limiting embodiments of the present disclosure.
  • FIGs. 46A-46B show human interneuron transplantation increases the power of gamma oscillations in the TG2576 AD mouse model during the resting phase, according to some non-limiting embodiments of the present disclosure.
  • FIG. 46A shows relative power with respect to the resting phase of theta (4-12 Hz, left) and gamma (20-60 Hz) oscillations in non-carrier (NCAR, gray), vehicle injected transgenic (VEH, red), and human cell transplanted transgenic (CELL, blue) in 24 hr EEG recording.
  • NCAR non-carrier
  • VEH vehicle injected transgenic
  • CELL human cell transplanted transgenic
  • FIGs. 47A-47C show embryonic induction of mTor, according to some non-limiting embodiments of the present disclosure. In utero electroporation of a constitutively active form of Rheb, a main transducer of the mTor pathway. Expression plasmid of Rheb-CA and GFP is shown in FIG. 47A, and the electroporation method is illustrated in FIG. 47B (at E15.5).
  • FIG. 47A In utero electroporation of a constitutively active form of Rheb, a main transducer of the mTor pathway. Expression plasmid of Rheb-CA and GFP is shown in FIG. 47A, and the electroporation method is illustrated in FIG. 47B (at E15.5).
  • FIG. 47A In utero electroporation of a constitutively active form of Rheb, a main transducer of the mTor pathway. Expression plasmid of Rheb-CA and GFP is shown in FIG. 47A
  • FIG. 48A-48B show histological validation of embryonic induction of mTor, according to some non-limiting embodiments of the present disclosure.
  • FIG. 48A shows GFP, GFPA, and pS6 expression in the mPFC of two different animals at P30.
  • GFAP is a marker of active gliosis, a hallmark of FCD.
  • FIG. 48B shows higher magnification images of the examples in FIG. 48A.
  • FIGs. 49A-49D show neonatal induction of mTor, according to some non- limiting embodiments of the present disclosure.
  • FIGs. 49A-49B show neonatal delivery of a constitutively active form of Rheb by AAVs. Diagram of an AAV backbone with Rheb-CA and GFP driven by the projection neuron CamKII promoter. AAVs were delivered into the mPFC in P0-P1 CD1 pups at several different doses.
  • FIG. 49C shows RhebCA/GFP- expressing cells correspond to cortical projection neurons (marked by NeuroD2), but not to GABAergic interneurons (marked by Lhx6).
  • FIG. 49D shows co-expression of GFP and phospho-S6 in transduced cells and induction of GFAP in the mPFC at P30.
  • FIGs. 50A-50B show histological validation of the neonatal induction of mTor in immunosuppressed mice, according to some non-limiting embodiments of the present disclosure.
  • FIG. 50A shows co-expression of GFP, Rheb, and phospho-S6 in transduced cells and induction of GFAP in the mPFC of Scid-beige mice at P30.
  • FIGs. 51A-51C show electrographic validation of the embryonic induction of mTor, according to some non-limiting embodiments of the present disclosure.
  • FIG. 51A shows examples of generalized seizures recorded with superficial electrodes in animals embryonically induced with Rheb-CA.
  • FIG. 51B shows average seizure rates from a cohort of 6 embryonically-induced animals (3 weeks recording).
  • FIG. 51C shows daily seizure recording of 3 animals with generalized seizures.
  • FIGs. 52A-52B shows electrographic validation of the neonatal induction of mTor, according to some non-limiting embodiments of the present disclosure.
  • FIGs. 52A- 52B shows examples of epileptiform activity recorded at 2 months post-implant with cortical electrodes in CD1 (FIG. 52A) and Scid-beige (FIG. 52B) animals induced with Rheb-CA AAVs neonatally.
  • DETAILED DESCRIPTION [0066] Provided herein are methods of treating seizure activity, e.g., mesial temporal lobe epilepsy (MTLE), using a cellular composition of pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells.
  • MTLE mesial temporal lobe epilepsy
  • a substantial portion, e.g., at least 90%, of the cells of the cellular composition are post-mitotic.
  • a method of the present disclosure includes identifying a subject in need of treating seizure activity; and administering a therapeutically effective amount of a cellular composition enriched for pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells.
  • the cellular composition administered to the subject includes (or is enriched for) pallial, MGE-type GABAergic interneuron cells derived from pluripotent stem cells (e.g., hESCs).
  • the method reduces the frequency of seizures in the subject, e.g., by at least about 50% in some embodiments.
  • administering the pluripotent stem cell-derived, MGE- type inhibitory (e.g., GABAergic) neuron cells can restore local inhibitory tone to reduce the frequency of seizures in the subject.
  • the MGE-type inhibitory (e.g., GABAergic) neuron cells include MGE-type inhibitory (e.g., GABAergic) interneuron cells.
  • the MGE-type inhibitory (e.g., GABAergic) neuron cells are of the pallial lineage.
  • the pluripotent stem cell-derived, MGE-type GABAergic neuron cells are pallial, MGE-type GABAergic interneuron cells.
  • the MGE-type inhibitory (e.g., GABAergic) neuron cells are of the subpallial lineage.
  • the pluripotent stem cell-derived, MGE-type GABAergic neuron cells are subpallial, MGE-type GABAergic neuron cells.
  • the administered cells locally disperse, mature into cortical/hippocampal-type interneurons, and persist in the subject’s temporal lobe, e.g. hippocampus, for an extended duration.
  • the high proportion of post- mitotic cells in the administered cellular composition promotes a stable cell fate of the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) after administration to the subject.
  • MGE-type inhibitory e.g., GABAergic
  • neuron cells e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells
  • administering the pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells reduces granule cell dispersion and/or neuronal degeneration in the subject’s temporal lobe.
  • MGE-type inhibitory neuron cells e.g., pluripotent stem cell- derived, pallial, MGE-type GABAergic interneuron cells
  • administering the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells treats seizure activity, e.g., MTLE, such as MTLE that does not respond to anti-seizure drugs.
  • MGE-type inhibitory neuron cells e.g., GABAergic neuron cells
  • methods of the present disclosure provide a cell therapy alternative to resection/ablation surgery for drug-resistant MTLE.
  • administering of the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) to the subject’s brain (e.g., hippocampus, cortex, and/or amygdala) provides a targeted treatment for the seizure activity that minimizes side effects such as behavioral abnormalities and/or adverse immunological reactions by the subject.
  • MGE-type inhibitory e.g., GABAergic
  • GABAergic neuron cells e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells
  • the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells are administered to one or more regions of the temporal lobe: hippocampus, subiculum, entorhinal cortex, and/or parahippocampal gyrus.
  • the interneurons, precursors, and/or pluripotent stem cells are genetically modified to evade the recipient's immune system (e.g., immune-cloaking).
  • seizure or “seizure activity” as used herein has its customary and ordinary meaning as understood by one of ordinary skill in the art in view of the present disclosure.
  • a seizure can include an uncontrolled, abnormal and/or synchronous brain activity, and/or one or more symptoms thereof.
  • reference to a seizure includes epileptic seizure-like discharges or epileptiform activity in the brain.
  • a seizure may cause one or more of changes in the level of consciousness, behavior, memory, or emotional states.
  • the seizure can be convulsive or non-convulsive.
  • a seizure can be provoked or unprovoked.
  • a seizure can include a focal seizure (e.g., focal aware seizure and/or focal impaired awareness seizure) or a focal to bilateral tonic-clonic seizure.
  • focal seizure e.g., focal aware seizure and/or focal impaired awareness seizure
  • focal to bilateral tonic-clonic seizure e.g., focal tonic-clonic seizure.
  • “Focal onset seizure” or “focal seizure” as used herein has its customary and ordinary meaning as understood by one of ordinary skill in the art in view of the present disclosure, and denotes a seizure that occurs in or originates from one hemisphere or a subpart thereof of a subject’s brain.
  • “Generalized seizure” as used herein has its customary and ordinary meaning to one of ordinary skill in the art in view of the present disclosure, and denotes a seizure that affects the whole brain or that is not limited to one hemisphere.
  • a focal onset seizure can become generalized in some cases.
  • a focal onset seizure can include a focal aware seizure and/or focal impaired awareness seizure.
  • “Epilepsy” as used herein has its customary and ordinary meaning as understood by one of ordinary skill in the art in view of the present disclosure.
  • An epilepsy refers to a disorder characterized by recurring seizures.
  • “Focal epilepsy” refers to recurring seizures that affect one hemisphere or a subpart thereof of a subject’s brain.
  • Cellular composition refers to an isolated collection or population of cells.
  • the composition can include, without limitation, primary cells, stem cells, cells differentiated from stem cells, and cell lines.
  • the cells of the composition can be suspended in, adhered to and/or embedded in any suitable medium or substrate.
  • a “progenitor” or “progenitor cell” as used herein refers to a mitotic cell that is differentiating from a pluripotent stem cell, and is capable of further differentiating into a terminally-differentiated cell (e.g., as determined by changes in marker expression).
  • a progenitor cell in some embodiments can differentiate into a desired terminally-differentiated cell (“on target”), or terminally-differentiated cell that is not desired (“off target”).
  • MGE-type as used herein with reference to progenitors, lineages, neurons, and interneurons, refers to cells that express markers expressed by cells in the MGE region of the developing brain, or by neurons differentiated from cells of the MGE region.
  • MGE progenitor cells express markers such as, Foxg1, homeobox gene Nkx2.1, LIM-homeobox genes Lhx6, Lhx7, or Lhx8. MGE progenitor cells are capable of differentiating into interneurons and/or projection neurons under suitable differentiation conditions.
  • PS cells may be from any one of a variety of organisms, including, e.g., human; primate; non-human primate; canine; feline; murine; equine; porcine; avian; camel; bovine; ovine, and so on.
  • “Express” as used herein refers to the presence of a gene product (e.g., mRNA and/or protein) in or associated with a cell or a group of cells at a level above a relevant reference level (e.g., a predetermined level for detecting the gene product, or a level of the gene product that effectively differentiates between populations of cells known to either express or not express the gene product). In some cases, the reference level is a background level of expression.
  • post-mitotic denotes a cell in a state after it has exited the cell cycle. Cell cycle exit may be reversible or irreversible. In some embodiments, a post-mitotic cell is terminally differentiated. A post-mitotic cell can be characterized by expression, or lack thereof, of one or more markers (e.g., Ki67, ASPM), and/or measuring incorporation, or lack thereof, of a nucleoside analog.
  • Effective amount refers to an amount sufficient to bring about a desired result.
  • “Therapeutically effective amount” as used herein refers to an amount sufficient for a therapeutic agent to bring about a therapeutically desired result.
  • “treat” or “treatment” refer to curing, preventing occurrence of, ameliorating, preventing deterioration of, reducing one or more symptoms of, and/or slowing the progress of a condition or disease.
  • “Subject” or “individual” as used herein can be any one of a variety of animals, such as a mammal. Mammals include, but are not limited to, humans, primates, horses, pigs, cows, dogs, cats, mice and rats, etc. In some embodiments, a subject can be male or female. “Subject” and “patient” are used interchangeably herein.
  • Transforming growth factor betas TGF- ⁇ s
  • TGFBs TGFB secreted proteins belonging to the subfamily of the transforming growth factor ⁇ (TGF ⁇ ) superfamily.
  • TGF ⁇ transforming growth factor ⁇
  • TGFBs TGFB1, TGFB2, TGFB3
  • the mature peptides may be found as homodimers or as heterodimers with other TGFB family members.
  • TGFBs interact with transforming growth factor beta receptors (TGF- ⁇ Rs, or TGFBRs) on the cell surface, which binding activates MAP kinase-, Akt-, Rho- and Rac/cdc42-directed signal transduction pathways, the reorganization of the cellular architecture and nuclear localization of SMAD proteins, and the modulation of target gene transcription.
  • TGF- ⁇ Rs transforming growth factor beta receptors
  • Inhibitors of TGFB signaling can be readily be identified by any of a number of suitable assays, for example competitive binding assays for binding to TGFB or TGFB receptors, or functional assays, e.g.
  • BMPs transforming growth factor ⁇
  • TGF ⁇ transforming growth factor ⁇
  • BMP1, BMP2, BMP3, BMP4, BMP5, BMP6, BMP7, BMP8a, BMP8b, BMP9/GDF, BMP10, BMP11/GDF11, BMP12/GDF7, BMP13/GDF6, BMP14/GDF5, BMP15/GDF9B) were first discovered by their ability to induce the formation of bone and cartilage.
  • BMPs interact with specific receptors on the cell surface, referred to as bone morphogenetic protein receptors (BMPRs). Signal transduction through BMPRs results in mobilization of members of the SMAD family of proteins, which in turn modulate transcription of target genes.
  • BMPRs bone morphogenetic protein receptors
  • Inhibitors of BMP signaling can readily be identified by any of a number of suitable assays, for example competitive binding assays for binding to BMP or BMP receptors, or functional assays, e.g., measuring enhancement of activity of downstream signaling proteins such as relocalization of SMADs, such as, BR-Smad to the nucleus and transcriptional activation of downstream gene targets.
  • suitable assays for example competitive binding assays for binding to BMP or BMP receptors, or functional assays, e.g., measuring enhancement of activity of downstream signaling proteins such as relocalization of SMADs, such as, BR-Smad to the nucleus and transcriptional activation of downstream gene targets.
  • Wnts refers to the family of highly conserved secreted signaling molecules which play key roles in both embryogenesis and mature tissues.
  • the human Wnt gene family has at least 19 members (Wnt-1, Wnt-2, Wnt-2B/Wnt-13, Wnt-3, Wnt3a, Wnt-4, Wnt-5A, Wnt-5B, Wnt-6, Wnt-7A, Wnt-7B, Wnt-8A, Wnt-8B, Wnt-9A/Wnt- 14, Wnt-9B/Wnt-15, Wnt-10A, Wnt-10B, Wnt-11 Wnt-16).
  • Wnt proteins modulate cell activity by binding to Wnt receptor complexes that include a polypeptide from the Frizzled (Fz) family of proteins and a polypeptide of the low-density lipoprotein receptor (LDLR)- related protein (LRP) family of proteins.
  • Wnt receptor complex Once activated by Wnt binding, the Wnt receptor complex will activate one or more intracellular signaling cascades. These include the canonical Wnt signaling pathway; the Wnt/planar cell polarity (Wnt/PCP) pathway; and the Wnt-calcium (Wnt/Ca2+) pathway.
  • “Sonic hedgehog” and “shh” as used herein refers to a member of the Hedgehog (Hh) protein family, that is a secreted glycoprotein that undergoes post- translational modifications, including auto-catalytic cleavage and cholesterol coupling to amino-terminal peptide to form the fragment that possesses the signaling activity. Hh binds to the 12-step transmembrane protein Ptch (Ptch1 and Ptch2), thereby alleviating Ptch- mediated suppression of Smoothened (Smo).
  • Notch refers to a signaling receptor in the Notch signaling pathway that controls cell fate during development, cell survival and cell proliferation.
  • the Notch receptor is a single-pass transmembrane receptor containing numerous tandem epidermal growth factor (EGF)-like repeats and three cysteine-rich Notch/LIN-12 repeats within a large extracellular domain.
  • Notch receptors are activated by single-pass transmembrane ligands of the Delta, Serrated, Lag-2 (DSL) family. Mammalian Notch receptors undergo cleavage to form the mature receptor and also following ligand binding to activate downstream signaling. A furin-like protease cleaves the Notch receptors during maturation to generate juxtamembrane heterodimers that comprise a non-covalently associated extracellular subunit and a transmembrane subunit held together in an auto- inhibitory state.
  • DSL Delta, Serrated, Lag-2
  • ADAM-type metalloprotease and a gamma-secretase the latter of which releases the intracellular domain (ICD) into the cytoplasm, allowing it to translocate into the nucleus to activate gene transcription.
  • Cleavage by ADAM occurs within the non-ligand binding cleavage domain within the membrane proximal negative regulatory region.
  • CDK or “cyclin dependent kinase” as used herein refers to a family of serine-threonine kinase proteins that regulate progression through the various phases of the cell cycle. CDKs use ATP as a substrate to phosphorylate diverse polypeptides in a sequence dependent manner.
  • Cyclins are a family of proteins characterized by a homology region, containing approximately 100 amino acids, termed the “cyclin box” which is used in binding to, and defining selectivity for, specific CDK partner proteins.
  • MAPK refers to one of three kinases that are part of the MAP (mitogen-activated protein) kinase (MAPK) pathway that regulates cell proliferation and/or differentiation.
  • the MAPK pathway encompasses a cascade of phosphorylation events involving three key kinases, namely Raf, MEK (MAP kinase kinase) and ERK (MAP kinase).
  • Raf Active GTP-bound Ras results in the activation and indirect phosphorylation of Raf kinase.
  • Raf then phosphorylates MEK1 and 2.
  • Activated MEK then phosphorylates its only known substrates, the MAP kinases, ERK1 and 2.
  • Phosphorylated ERK dimerizes and then translocates to the nucleus where it accumulates.
  • ERK is involved in several important cellular functions, including but not limited to nuclear transport, signal transduction, DNA repair, nucleosome assembly and translocation, and mRNA processing and translation.
  • Treatment of cells with growth factors leads to the activation of ERK1 and 2 which results in proliferation and, in some cases, differentiation.
  • K indicates units of a thousand
  • M indicates units of a million
  • 200K indicates “200,000”
  • 1.5M indicates “1,500,000.”
  • the singular terms “a,” “an,” and “the” include plural referents unless context clearly indicates otherwise.
  • the word “or” is intended to include “and” unless the context clearly indicates otherwise.
  • the abbreviation, “e.g.” is used herein to indicate a non- limiting example.
  • e.g. is synonymous with the term “for example.”
  • the term “about” as used herein to, for example, define the values and ranges of molecular weights means that the indicated values and/or range limits can vary within ⁇ 20%, e.g., within ⁇ 10%, including within ⁇ 5%.
  • the use of “about” before a number includes the number itself. For example, “about 5” provides express support for “5.”
  • MTLE mesial temporal lobe epilepsy
  • the method 100a can include at block 110a identifying a subject in need of treating seizure activity.
  • the method can further include at block 120a administering (e.g., intracranially administering) a therapeutically effective amount of a cellular composition comprising pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells, as described herein.
  • pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells can in some embodiments be post-mitotic cells, where for example, at least 90% of the cells are post-mitotic cells.
  • a cellular composition includes pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells.
  • a method 100b of the present disclosure can include: at block 110b identifying a subject in need of treating seizure activity.
  • the method can further include at block 120b administering (e.g., intracranially administering) a therapeutically effective amount of a cellular composition comprising pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells, as described herein.
  • a subject treated by the methods of the present disclosure can have hyperexcitability and/or hyperactivity in neurons or a network thereof.
  • the subject is suffering from hyperexcitability and/or hyperactivity in neurons or a network thereof, where the hyperexcitability and/or hyperactivity is associated with a neurological condition.
  • the subject has a neurological condition that is associated with neuronal hyperexcitability and/or hyperactivity in one or more brain regions.
  • the subject has a neurodegenerative disease, such as but not limited to Alzheimer’s disease (AD) or Parkinson’s disease (PD) that is associated with the neuronal hyperexcitability and/or hyperactivity.
  • AD Alzheimer’s disease
  • PD Parkinson’s disease
  • the subject suffers from epileptic seizure-like discharges in the brain associated with Alzheimer’s disease, focal cortical dysplasia (FCD), or amnesic mild cognitive impairment (aMCI).
  • subject has AD and exhibits one or more symptoms of AD.
  • the AD subject has or exhibits symptoms of tauopathy.
  • the subject has schizophrenia, spasticity, and/or neuropathic pain that is associated with the neuronal hyperexcitability and/or hyperactivity.
  • the subject has a neuropsychiatric disorder associated with the neuronal hyperexcitability and/or hyperactivity.
  • the subject is suffering from hyperexcitability and/or hyperactivity in one or more brain regions, e.g., in the temporal lobe. In some embodiments, the subject is suffering from hyperexcitability and/or hyperactivity in the hippocampus. In some embodiments, the subject is suffering from hyperexcitability and/or hyperactivity in one or more of the following regions of the temporal lobe: hippocampus, subiculum, entorhinal cortex, and/or parahippocampal gyrus. [0093] In some embodiments, the subject is in need of treatment of seizures and/or symptoms thereof. In some embodiments, the seizure is convulsive.
  • the seizure is non-convulsive (e.g., is an absence seizure). In some embodiments, the seizure is a focal onset seizure, or a focal epilepsy. In some embodiments, the seizure is localized to and/or originates from the temporal lobe of the left or right hemisphere of the subject’s brain. In some embodiments, the seizure is localized to and/or originates from one or more subregions of the temporal lobe. In some embodiments, the seizure is localized to and/or originates from the subiculum, entorhinal cortex, and/or parahippocampal gyrus.
  • the seizure is localized to and/or originates from the hippocampus (e.g., left and/or right hippocampus) and/or from the amygdala (e.g., left or right amygdala).
  • the subject suffers from a focal onset seizure that develops into a generalized seizure.
  • the subject does not have a generalized seizure.
  • the subject has a chronic seizure (e.g., a recurring seizure).
  • the subject has an epilepsy, e.g., a focal epilepsy or a temporal lobe epilepsy.
  • the subject has temporal lobe epilepsy (TLE) (e.g., drug-resistant TLE).
  • TLE temporal lobe epilepsy
  • the subject suffers from a neocortical onset focal epilepsy.
  • the subject suffers from focal seizure activity.
  • the subject has mesial temporal lobe epilepsy (MTLE).
  • MTLE mesial temporal lobe epilepsy
  • the subject has AD with epileptic activity.
  • the subject has AD and has, or suffers from symptoms of, tauopathy.
  • the subject has been diagnosed as having or suffering from seizure activity.
  • the subject has been diagnosed to have one or more conditions underlying the seizures (e.g., an infection, disease, stroke, trauma, neurological disorder, metabolic disorder, developmental disorder, drug exposure, or stress).
  • the subject can be identified as in need of treating seizure activity by any suitable option.
  • the subject is identified as having or suffering from seizure activity based on a clinical manifestation of symptoms of seizure.
  • the subject is experiencing or has experienced one or more symptoms of the seizure.
  • the subject is identified as suffering from seizure activity based on a subjective assessment of one or more symptoms of the seizure.
  • the subject is identified as suffering from seizure activity based on brain monitoring.
  • the subject is identified as suffering from seizure activity after undergoing one or more brain monitoring such as, without limitation, computed tomography (CT) scan, magnetic resonance imaging (MRI), MR spectroscopy (MRS), functional MRI (fMRI), electroencephalography (EEG), intracranial EEG, positron emission tomography (PET), and single photon emission computed tomography (SPECT).
  • CT computed tomography
  • MRI magnetic resonance imaging
  • MRS MR spectroscopy
  • fMRI functional MRI
  • EEG electroencephalography
  • intracranial EEG intracranial EEG
  • PET positron emission tomography
  • SPECT single photon emission computed tomography
  • the seizure activity is an electrographic seizure.
  • the subject is identified as having or suffering from electrographic seizures.
  • the electrographic seizure is detected using an EEG.
  • an electrographic seizure includes a spike train of about 1 Hz or more, e.g., about 2 Hz, about 3 Hz, about 4Hz, about 5 Hz or more, or at a frequency in a range defined by any two of the preceding values (e.g., 1-5 Hz, 2-5 Hz, 3-4 Hz, 3-5 Hz, etc.), for example, as detected by EEG.
  • an electrographic seizure includes a spike train having a duration of about 5 seconds or longer, e.g., about 10 seconds, about 15 seconds, about 20 seconds, about 30 seconds or longer, or a period of time in a range defined by any two of the preceding values (e.g., 5-30 seconds, 10-20 seconds, 15-30 seconds, 5-20 seconds, etc.).
  • an electrographic seizure includes an inter-event (or inter-spike train) interval of about 1 second or more, e.g., about 2 seconds, about 3 seconds, about 5 seconds, about 10 seconds, about 15 seconds, about 20 seconds, about 30 seconds or more, or a period of time in a range defined by any two of the preceding values (e.g., 1-30 seconds, 2-20 seconds, 3-30 seconds, 5-15 seconds, 5-30 seconds, etc.).
  • a chronic or recurring seizure can occur at one or more frequencies.
  • the seizure occurs at a frequency of once per 30 minutes or more, e.g., 2 times per 30 minutes or more, about 5 times per 30 minutes or more, e.g., about 10 times per 30 minutes or more, about 15 times per 30 minutes or more, about 20 times per 30 minutes or more, about 30 times per 30 minutes or more, about 50 times per 30 minutes or more, or at a frequency in a range defined by any two of the preceding values (e.g., 1-50 times/30 minutes, 2-30 times/30 minutes, 3-20 times/30 minutes, 5-15 times/30 minutes, 10-15 times/30 minutes, etc.).
  • the seizure occurs at a frequency of once per week or more, e.g., 2 times per week or more, about 5 times per week or more, about 10 times per week or more, about 15 times per week or more, about 20 times per week or more, about 30 times per week or more, about 50 per week times or more, or at a frequency in a range defined by any two of the preceding values (e.g., 1-50 times/week, 2-30 times/week, 3-20 times/week, 5-15 times/week, 10-15 times/week, etc.).
  • the seizure occurs at a frequency of once per month or more, e.g., 2 times per month or more, about 5 times per month or more, about 10 times per month or more, about 15 times per month or more, about 20 times per month or more, about 30 times per month or more, about 50 times per month or more, or at a frequency in a range defined by any two of the preceding values (e.g., 1-50 times/month, 2-30 times/month, 3-20 times/month, 5-15 times/month, 10-15 times/month, etc.).
  • the frequency at which the seizure occurs does not vary substantially over a month, two months, 3 months, 4 months, 6 months, or over 12 months or more. In some embodiments, the frequency at which the seizure occurs (without administering the therapeutic compositions of the present disclosure) increases over a month, two months, 3 months, 4 months, 6 months, or over 12 months or more. [0097] The length of an episode of a seizure from which the subject is suffering can vary.
  • an episode of the seizure lasts for about 5 second or longer, e.g., about 10 seconds or longer, about 30 seconds or longer, about 60 seconds or longer, about 90 seconds or longer, about 120 seconds or longer, about 180 seconds or longer, about 4 minutes or longer, about 5 minutes or longer, about 10 minutes or longer, about 15 minutes or longer, about 20 minutes or longer, or about 30 minutes or longer, or a period of time in a range defined by any two of the preceding values. In some embodiments, an episode of the seizure lasts from about 5 second to about 30 minutes.
  • an episode of the seizure lasts from about 5-10 seconds, 10-30 seconds, 30-60 seconds, 60-90 seconds, 90- 120 seconds, 120-180 seconds, 3-4 minutes, 4-5 minutes, 5-10 minutes, 10-15 minutes, 15-20 minutes, or 20-30 minutes.
  • the seizure activity is a chronic condition.
  • the seizure activity is a provoked seizure, or a non-provoked seizure.
  • the seizure activity is associated with an infection, disease (e.g., a tumor), stroke, trauma, neurological disorder, metabolic disorder, developmental disorder, drug exposure (e.g., drug overdose), focal cortical dysplasia, tuberous sclerosis, or stress.
  • the seizure activity is due to a traumatic brain injury (e.g., to the temporal lobe), focal cortical dysplasia, tuberous sclerosis, or due to a neurological disorder. In some embodiments, the seizure activity is due to a stroke, a tumor, or a developmental disorder. In some embodiments, the subject has mesial temporal sclerosis. In some embodiments, the subject has hippocampal sclerosis, and/or an extrahippocampal sclerosis (e.g., sclerosis of the amygdala). In some embodiments, the subject has one or more lesions, e.g., epileptogenic lesions, in the brain.
  • lesions e.g., epileptogenic lesions
  • the subject has one or more lesions, e.g., epileptogenic lesions, in the temporal lobe. In some embodiments, the subject has 1, 2, 3, 4, 5 or more lesions, e.g., epileptogenic lesions, in the brain (e.g., in the temporal lobe). In some embodiments, the subject has increased granule cell dispersion in the temporal lobe, e.g., in the hippocampus. In some embodiments, the cause of the seizure is unknown. [0099] In some embodiments, the seizure activity is resistant to a conventional anti-seizure therapy.
  • the subject’s seizure activity is not adequately treated after treatment with one, two or more anti-seizure therapies.
  • the subject has drug-resistant TLE, e.g., drug-resistant MTLE.
  • Drug-resistant seizure or epilepsy as used herein has its ordinary and customary meaning as understood by one of ordinary skill in the art in view of the present disclosure.
  • drug- resistant TLE is resistant to treatment with carbamazepine or levetiracetam.
  • the method includes identifying mesial temporal sclerosis in the subject’s brain.
  • the method includes identifying hippocampal sclerosis, and/or an extrahippocampal sclerosis (e.g., sclerosis of the amygdala).
  • the method includes identifying a lesion, e.g., an epileptogenic legion, in the subject’s brain (such as in the temporal lobe). Any suitable option can be used to identify a lesion or mesial temporal sclerosis in the subject’s brain.
  • the method includes using one or more suitable imaging techniques (e.g., computed tomography (CT) scan, magnetic resonance imaging (MRI), MR spectroscopy (MRS), functional MRI (fMRI), electroencephalography (EEG), intracranial EEG, positron emission tomography (PET), and single photon emission computed tomography (SPECT), etc.) to identify mesial temporal sclerosis or a lesion, e.g., an epileptogenic legion, in the subject’s brain, before, concurrent to, and/or after administering the cellular composition.
  • CT computed tomography
  • MRI magnetic resonance imaging
  • MRS MR spectroscopy
  • fMRI functional MRI
  • EEG electroencephalography
  • PET positron emission tomography
  • SPECT single photon emission computed tomography
  • the method includes using one or more suitable imaging techniques, as described herein, to determine that the mesial temporal sclerosis is reduced or eliminated after administering the cellular composition. In some embodiments, the method includes using one or more suitable imaging techniques, as described herein, to determine that the lesion is reduced or eliminated after administering the cellular composition. [0101] In some embodiments, the method includes using one or more suitable brain activity monitoring techniques to determine whether the subject exhibits seizure activity, e.g., before and/or after administering the cellular composition.
  • the method includes using one or more suitable brain activity monitoring techniques, as described herein, to determine that the frequency of seizures is reduced after administering the therapeutically effective amount of the cellular composition containing the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells).
  • MGE-type inhibitory e.g., GABAergic
  • neuron cells e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells.
  • the method includes performing one or more of computed tomography (CT) scan, magnetic resonance imaging (MRI), MR spectroscopy (MRS), functional MRI (fMRI), electroencephalography (EEG), intracranial EEG, positron emission tomography (PET), and single photon emission computed tomography (SPECT) on the subject.
  • CT computed tomography
  • MRI magnetic resonance imaging
  • MRS MR spectroscopy
  • fMRI functional MRI
  • EEG electroencephalography
  • intracranial EEG intracranial EEG
  • PET positron emission tomography
  • SPECT single photon emission computed tomography
  • seizure activity is measured by self-assessment of the frequency, severity and/or type of seizure experienced by the subject over a suitable time period.
  • a subject can make a self-assessment of the frequency, severity and/or type of the seizure using any suitable option.
  • the subject has described the frequency, severity and/or type of seizure experienced over a suitable time period (e.g., daily, weekly, monthly, etc.) in a seizure diary.
  • the subject has orally conveyed the frequency, severity and/or type of seizure experienced over a suitable time period (e.g., daily, weekly, monthly, etc.).
  • the method includes comparing the frequency, severity and/or type of seizure experienced by the subject before and after administration of the cellular composition as recorded by the subject in a seizure diary. [0103]
  • the method includes administering the therapeutically effective amount of the cellular composition to the temporal lobe of the subject.
  • the method includes administering the therapeutically effective amount of the cellular composition to the temporal lobe ipsilateral to seizure activity in the subject’s brain (e.g., ipsilateral to a focal onset seizure).
  • the method includes administering the therapeutically effective amount of the cellular composition to the left temporal lobe.
  • the method includes administering the therapeutically effective amount of the cellular composition to the right temporal lobe. In some embodiments, the method includes administering the cellular composition only to the temporal lobe ipsilateral to the focal onset seizure. In some embodiments, the method includes administering the therapeutically effective amount of the cellular composition to the temporal lobe bilaterally. In some embodiments, the cellular composition comprises genetically modified or gene edited cells, e.g., to evade the recipient's immune system, as described herein.
  • the cellular composition is administered as one or more deposits in the subject’s brain. In some embodiments, the cellular composition is administered as 1, 2, 3, 4, 5, 6, 7, 8 or more deposits in the subject’s brain. In some embodiments, the method include administering the cellular composition to one or more sites, e.g., 2, 3, 4, 5, 6, 7, 8, or more sites, in the hippocampus, cortex, subiculum, entorhinal cortex, parahippocampal gyrus, and/or amygdala.
  • sites e.g., 2, 3, 4, 5, 6, 7, 8, or more sites, in the hippocampus, cortex, subiculum, entorhinal cortex, parahippocampal gyrus, and/or amygdala.
  • the cellular composition is administered to one or more distinct sites (e.g., target sites) within the temporal lobe (e.g., the hippocampus, subiculum, entorhinal cortex, parahippocampal gyrus, and/or amygdala) ipsilateral to the focal onset seizure.
  • Suitable sites within the temporal lobe include, without limitation, the hippocampus, cortex, amygdala, subiculum, entorhinal cortex, and/or the parahippocampal gyrus.
  • the cellular composition is administered to one or more sites in the temporal lobe ipsilateral to the focal onset seizure.
  • the cells are administered to at least 1, 2, 3, 4, 5, 6, 7, or 8 or more different sites within the subject’s temporal lobe ipsilateral to the focal onset seizure.
  • administration of the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells
  • brain e.g., temporal lobe: hippocampus, subiculum, entorhinal cortex, and parahippocampal gyrus
  • the cells of the composition are administered to, around, or distal to, a site of mesial temporal sclerosis in the subject’s brain. In some embodiments, the number of cells administered (per hemisphere or per deposit) depends on the size and/or extent of mesial temporal sclerosis in the subject’s brain. [0106] In some embodiments, the cells of the composition are administered to, around, or distal to, one or more sites of a lesion, e.g., epileptogenic lesion, in the subject’s brain (e.g., temporal lobe).
  • a lesion e.g., epileptogenic lesion
  • the number of cells administered depends on the size and/or extent of a lesion (e.g., epileptogenic lesion).
  • the cells of the composition are administered to, around, or distal to, one or more sites within the subject’s brain identified by functional neuroimaging.
  • the cells of the composition are administered to, around, or distal to, one or more sites identified as a seizure onset zone using functional neuroimaging.
  • the cells of the composition are administered to, around, or distal to, one or more sites identified as an epileptogenic zone using functional neuroimaging. Any suitable option for functional neuroimaging can be used.
  • functional neuroimaging comprises one or more of PET, SPECT, magnetoencephalogram/magnetic source imaging (MEG/MSI), diffusion tensor imaging (DTI), fMRI, fMRI-EEG, MR spectroscopy (MRS), arterial spin labeling (ASL).
  • the subject does not or is not known to have a mesial temporal sclerosis or a lesion.
  • Any suitable volume of the cellular composition can be administered per deposit.
  • the cellular composition is delivered in a volume of, of about, or of at most 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 8, 6, 5, 4, 3, 2 ⁇ L per deposit, or of, of about, or of at least 0.1, 0.5, 0.8, 1, 1.2, 1.5, 2, 2.5, 3 ⁇ L per deposit, or a volume per deposit in a range defined by any two of the preceding values (e.g., 0.1-100 ⁇ L per deposit, 0.1-50 ⁇ L per deposit, 0.1-20 ⁇ L per deposit, 0.5-10 ⁇ L per deposit, 1.0-5 ⁇ L per deposit, 1.5 -4 ⁇ L per deposit, 1-2 ⁇ L per deposit, 2-4 ⁇ L per deposit, etc.).
  • the cellular composition is delivered in a volume of about 50 ⁇ L or less (e.g., 1-50 ⁇ L) per deposit. In some embodiments, the cellular composition is delivered in a volume of about 20 ⁇ L or less (e.g., 1-20 ⁇ L) per deposit. In some embodiments, the cellular composition is delivered in a volume of about 10 ⁇ L or less (e.g., 1-10 ⁇ L) per deposit. [0109] Any suitable number of the cells can be administered to the subject.
  • the cellular composition administered to the subject includes, per hemisphere, about 1 x 10 4 cells or more, about 2 x 10 4 cells or more, about 3 x 10 4 cells or more, about 5 x 10 4 cells or more, about 1 x 10 5 cells or more, about 2 x 10 5 cells or more, about 5 x 10 5 cells or more, about 1 x 10 6 cells or more, about 2 x 10 6 cells or more, about 5 x 10 6 cells or more, about 1 x 10 7 cells or more, about 2 x 10 7 cells or more, about 5 x 10 7 cells or more, about 1 x 10 8 cells or more, about 1 x 10 9 cells or more, about 2 x 10 9 cells or more, about 5 x 10 9 cells or more, about 1 x 10 10 cells or more, about 2 x 10 10 cells or more, about 5 x 10 9 cells or more, about 1 x 10 10 cells or more, about 2 x 10 10 cells or more, about 5 x 10 9 cells or more, about 1 x 10 10 cells or
  • the cellular composition administered to the subject includes, per hemisphere, from about 1 x 10 4 to about 1 x 10 8 cells, from about 2 x 10 4 to about 5 x 10 7 cells, from about 5 x 10 4 to about 1 x 10 7 cells, from about 1 x 10 5 to about 1 x 10 7 cells, from about 2 x 10 5 to about 5 x 10 6 cells, from about 5 x 10 5 to about 5 x 10 6 cells, from about 3 x 10 4 to about 1 x 10 12 cells, from about 3 x 10 4 to about 1 x 10 11 cells, from about 1 x 10 6 to about 1 x 10 10 cells, or from about 3 x 10 4 to about 2 x 10 6 cells.
  • the cellular composition administered to the subject includes, per hemisphere, from about 1 x 10 5 to about 1 x 10 9 cells, from about 2 x 10 5 to about 5 x 10 8 cells, from about 5 x 10 5 to about 1 x 10 8 cells, from about 1 x 10 6 to about 1 x 10 8 cells, from about 2 x 10 6 to about 5 x 10 7 cells, from about 5 x 10 6 to about 5 x 10 7 cells, from about 3 x 10 5 to about 1 x 10 12 cells, from about 3 x 10 5 to about 1 x 10 11 cells, from about 1 x 10 6 to about 1 x 10 10 cells, or from about 3 x 10 6 to about 5 x 10 7 cells.
  • the cellular composition administered to the subject includes, per hemisphere, about 1 x 10 7 cells to about 5 x 10 7 cells.
  • the number of cells administered to the subject per deposit is about 1 x 10 3 cells or more, about 2 x 10 3 cells or more, about 5 x 10 3 cells or more, about 1 x 10 4 cells or more, about 2 x 10 4 cells or more, about 5 x 10 4 cells or more, about 1 x 10 5 cells or more, about 2 x 10 5 cells or more, about 5 x 10 5 cells or more, about 1 x 10 6 cells or more, about 2 x 10 6 cells or more, about 5 x 10 6 cells or more, about 1 x 10 7 cells or more, about 1 x 10 7 cells or more, about 2 x 10 7 cells or more, about 5 x 10 7 cells or more, about 1 x 10 8 cells or more, about 1 x 10 9 cells or more cells, or a number of cells within a range defined by any two of the preced
  • the cellular composition is divided equally for administering to multiple sites, such that each deposit includes approximately the same number of cells of the composition.
  • at least two different deposits include substantially different numbers of cells of the composition.
  • the number of cells administered in two different deposits differs by about 50% or less, e.g., about 40% or less, about 30% or less, about 20% or less, about 10% or less, about 5% or less, about 2% or less, or at most by a percentage within a range defined by any two of the preceding values (e.g., at most 2-50%, 2-40%, 5-30%, 5-20%, or 10-20%, etc.).
  • the number of cells administered to the subject is based on a scaling factor applied to the number of cells administered in preclinical studies using a species that is different from the subject.
  • the scaling factor takes into account a ratio of the volume of a brain region (e.g., hippocampus) between the species used in the preclinical studies and the species to which the subject belongs.
  • the species used in preclinical studies is a mouse and the subject is a human subject, where the ratio of the volume of a brain region (e.g., hippocampus) between the two species is between about 100 and about 200, e.g., between about 120 and about 190, between about 130 and about 180, between about 140 and about 180, between about 150 and 170.
  • the species used in preclinical studies is a mouse and the subject is a human subject, where the ratio of the volume of a brain region (e.g., hippocampus) between the two species is between about 150 and 170.
  • the species used in preclinical studies is a mouse and the subject is a human subject
  • the scaling factor is at least about 5 fold, e.g., at least about 6 fold, at least about 7 fold, at least about 8 fold, at least about 9 fold, at least about 10 fold, at least about 12 fold, at least about 14 fold, at least about 16 fold, at least about 18 fold, at least about 20 fold, at least about 25 fold, at least about 30 fold, at least about 50 fold, at least about 75 fold, at least about 100 fold, or a fold difference in a range defined by any two of the preceding values (e.g., 5-100 fold, 5-75 fold, 5-50 fold, 6-30 fold, 6-25 fold, 7-20 fold, 8-12 fold, 18-25 fold, etc.).
  • the species used in preclinical studies is a mouse and the subject is a human subject, where the scaling factor is about 10 fold. In some embodiments, the species used in preclinical studies is a mouse and the subject is a human subject, where the scaling factor is about 20 fold.
  • the methods can employ any suitable option for administering the cellular composition to the subject’s brain. In general, the cells are administered intracranially. In some embodiments, the cells are administered using a stereotactic system. In some embodiments, administering includes injecting or implanting the cellular composition of the present disclosure into one or more target sites in the subject.
  • administering includes injecting or implanting the cellular composition of the present disclosure as one or more deposits in the subject’s brain, as described herein.
  • the cells of the present disclosure can be inserted into a delivery device, which facilitates introduction by injection or implantation of the cells into the subject’s brain.
  • delivery devices include a tubular structure with an internal compartment, e.g., cannula, or catheters, for holding the cells and fluids and/or for injecting cells and fluids into the body of a subject.
  • the tubular structure additionally have a needle tip through which the cells can be introduced into the subject at a desired location.
  • the method includes using a cannula or catheter, or similar device, to administer the cellular composition to a subject (e.g., to the subject’s brain).
  • the method includes using a delivery device, as described herein, to administer the cellular composition to the subject (e.g., to the subject’s brain).
  • the method includes detecting the position of the delivery device (for example, the proximal end (e.g., the subject-facing end) of the delivery device) holding the cellular composition in the subject’s brain while, or for at least some portion of, administering the cellular composition to a subject.
  • the cellular composition includes a contrast agent that facilitates visualizing the position of the delivery device (for example, the proximal end (e.g., the subject-facing end) of the delivery device) in the subject’s brain during administration of the cellular composition.
  • the method includes using MRI to visualize the administration or delivery of the cellular composition (e.g., where the delivery vehicle includes an MRI contrast agent).
  • the cellular composition of the present disclosure, or a portion thereof can be in any suitable form for inserting into the delivery device.
  • the method includes formulating the cellular composition of the present disclosure, or a portion thereof, in a suitable form for inserting into the delivery device.
  • the cells can be suspended in a solution or embedded in a support matrix when contained in such a delivery device.
  • the term “solution” includes a pharmaceutically acceptable vehicle, carrier, or diluent in which the cells remain viable.
  • Pharmaceutically acceptable vehicles, carriers, and diluents can include, without limitation, saline, aqueous buffer solutions, solvents and/or dispersion media.
  • the solution is sterile and fluid to facilitate delivery.
  • the solution is stable under the conditions of manufacture and storage and preserved against the contaminating action of microorganisms such as bacteria and fungi through the use of, for example, parabens, chlorobutanol, phenol, ascorbic acid, thimerosal, and the like.
  • solutions of the present disclosure are prepared in a pharmaceutically acceptable carrier or diluent and, as required, other ingredients enumerated above, followed by filter sterilization.
  • the cellular composition is provided in a suitable delivery vehicle.
  • the delivery vehicle includes pharmaceutically acceptable salts, supplements, lipid polymers, non-ionic surfactants, and/or MRI contrast agents, such as, without limitation, gadolinium.
  • the delivery vehicle includes a non-ionic surfactant, e.g., a poloxamer.
  • a non-ionic surfactant e.g., a poloxamer.
  • Suitable poloxamers include, without limitation, P124, P188, P237, P338, and/or P407. Any suitable amount of the poloxamer can be included in the delivery vehicle.
  • the delivery vehicle includes, v/v, about 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, or a percentage in a range defined by any two of the preceding values (e.g., 0.01%-2%, 0.05%-1%, 0.1%-0.5%, 0.2%-1.5%, etc.) of the poloxamer.
  • the delivery vehicle includes a poloxamer at 0.01%-2%, v/v.
  • the delivery vehicle includes a poloxamer at 0.1%-1%, v/v.
  • the delivery vehicle includes a preservation supplement (e.g., neural supplements, B27, N2, buffers, CSB, trehalose, sugars, salts, lipids, proteins, reducing agents, and/or Hypothermosol®). Any suitable amount of the preservation supplement can be included in the delivery vehicle.
  • a preservation supplement e.g., neural supplements, B27, N2, buffers, CSB, trehalose, sugars, salts, lipids, proteins, reducing agents, and/or Hypothermosol®. Any suitable amount of the preservation supplement can be included in the delivery vehicle.
  • the delivery vehicle includes, v/v, about 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or a percentage in a range defined by any two of the preceding values (e.g., 1-20%, 2-15%, 5-15%, 5-20%, etc.) of the preservation supplement.
  • the delivery vehicle includes a base medium. Any suitable based medium can be used.
  • the base medium includes, without limitation, aCSF, HBSS, MEM, DMEM, L-15, neurobasal medium, and combinations thereof.
  • the delivery vehicle includes a contrast agent. Any suitable contrast agent for imaging applications can be used.
  • the contrast agent is a paramagnetic contrast agent.
  • the contrast agent is an MRI contrast agent, including, without limitation, a gadolinium- or manganese-based contrast agent.
  • the contrast agent is an iodine-based or barium-based contrast agent.
  • the delivery vehicle includes one or more salts, e.g., sodium chloride, potassium chloride, etc.
  • the delivery vehicle includes a suitable buffer at physiological pH.
  • the cellular composition includes one or more salts, e.g., sodium chloride, potassium chloride, etc.
  • the cellular composition includes a salt (e.g., sodium chloride) at a concentration of, of about, or of at least 100, 120, 140, 160, 180, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, or 400 mM, or an osmolality of, of about, or of at most 600, 590, 580, 570, 560, 550, 540, 530, 520, 510, 500, 490, 480, 470, 460, 450, 440, 430, 420, 410, or 400 mM, or at a concentration in a range defined by any two of the preceding values (e.g., 100-600 mM, 200-500 mM, 150-450 mM, 250-500 mM, 300-450 mM, etc.).
  • a salt e.g.
  • the cellular composition includes sodium chloride at a concentration of 100-600 mM. In some embodiments, the cellular composition includes sodium chloride at a concentration of 100-600 mM. In some embodiments, the cellular composition has an osmolality of, of about, or of at least 100, 120, 140, 160, 180, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, or 500 mOsm/kg, or an osmolality of, of about, or of at most 1,000, 900, 800, 750, 700, 690, 680, 670, 660, 650, 640, 630, 620, 610, 600, 590, 580, 570, 560, 550, 540,
  • the cellular composition has an osmolality of at least 200 mOsm/kg. In some embodiments, the cellular composition has an osmolality of at least 300 mOsm/kg. In some embodiments, the cellular composition has an osmolality of 100-900 mOsm/kg. In some embodiments, the cellular composition has an osmolality of 300-500 mOsm/kg. [0119] In some embodiments, the cellular composition includes a high concentration of cells (e.g., pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells) in suspension, e.g., when administered to the subject.
  • cells e.g., pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells
  • a sufficiently high concentration of cells in the cellular composition effectively raises the viscosity such that the cellular composition can be held stably in a defined volume at the tip of a cannula, or a catheter, or similar delivery device, where the rest of the internal compartment of the cannula can be filled with a cell-free liquid chase vehicle or inner stylet.
  • the cellular composition includes cells at a concentration of about 0.1 x 10 6 cells per microliter or more, e.g., about 0.2 x 10 6 cells per microliter, about 0.3 x 10 6 cells per microliter, about 0.5 x 10 6 cells per microliter, about 0.75 x 10 6 cells per microliter, about 1 x 10 6 cells per microliter, about 1.5 x 10 6 cells per microliter, about 2 x 10 6 cells per microliter, about 3 x 10 6 cells per microliter, about 4 x 10 6 cells per microliter or more, or at a concentration in a range defined by any two of the preceding values (e.g., 0.1 x 10 6 -4 x 10 6 cells per microliter, 0.2 x 10 6 -2 x 10 6 cells per microliter, 0.2 x 10 6 -1.5 x 10 6 cells per microliter, 0.1 x 10 6 -3 x 10 6 cells per microliter, etc.).
  • the cellular composition includes cells at a concentration of about 1 x 10 5 cells/ ⁇ L or greater, and up to about 2 x 10 6 cells per microliter. In some embodiments, the cellular composition includes cells at a concentration of, of about, or of at least 0.1 x 10 6 , 0.2 x 10 6 , 0.3 x 10 6 , 0.4 x 10 6 , 0.5 x 10 6 , 0.6 x 10 6 , 0.7 x 10 6 , 0.8 x 10 6 , 0.9 x 10 6 , 1 x 10 6 , 1.1 x 10 6 , 1.2 x 10 6 , 1.3 x 10 6 , 1.4 x 10 6 , 1.5 x 10 6 , 1.6 x 10 6 , 1.7 x 10 6 , 1.8 x 10 6 , 1.9 x 10 6 , or 2 x 10 6 cells per microliter, or at a concentration in a range defined by any two of the preceding values (e.g., 0.1 x 10 6
  • the cellular composition for administering to the subject includes cells at a concentration of about 0.8 x 10 6 cells per microliter or more (e.g., about 0.9 x 10 6 cells per microliter, about 1.0 x 10 6 cells per microliter, about 1.1 x 10 6 cells per microliter, about 1.2 x 10 6 cells per microliter, about 1.5 x 10 6 cells per microliter, including up to about 2.0 x 10 6 cells per microliter).
  • the cellular composition includes cells at a concentration of about 0.5 x 10 6 cells per microliter to about 1.5 x 10 6 cells per microliter.
  • the cellular composition includes cells at a concentration of about 0.6 x 10 6 cells per microliter to about 1.2 x 10 6 cells per microliter. In some embodiments, the cellular composition includes cells at a concentration of about 0.9 x 10 6 cells per microliter to about 1.2 x 10 6 cells per microliter. In some embodiments, the cellular composition includes cells at a concentration of about 1 x 10 6 cells per microliter. [0120] In some embodiments, the therapeutically effective amount of the cellular composition is administered at a concentration of about 1 x 10 5 cells/ ⁇ L or greater.
  • the therapeutically effective amount of the cellular composition is administered at a concentration of about 1 x 10 5 cells/ ⁇ L or greater, and up to about 2 x 10 6 cells per microliter. In some embodiments, the therapeutically effective amount of the cellular composition is administered at a concentration of, of about, or of at least 0.1 x 10 6 , 0.2 x 10 6 , 0.3 x 10 6 , 0.4 x 10 6 , 0.5 x 10 6 , 0.6 x 10 6 , 0.7 x 10 6 , 0.8 x 10 6 , 0.9 x 10 6 , 1 x 10 6 , 1.1 x 10 6 , 1.2 x 10 6 , 1.3 x 10 6 , 1.4 x 10 6 , 1.5 x 10 6 , 1.6 x 10 6 , 1.7 x 10 6 , 1.8 x 10 6 , 1.9 x 10 6 , or 2 x 10 6 cells per microliter, or at a concentration in a range defined by any two of the
  • the therapeutically effective amount of the cellular composition is administered at a concentration of about 0.5 x 10 6 cells per microliter to about 2 x 10 6 cells per microliter. In some embodiments, the therapeutically effective amount of the cellular composition is administered at a concentration of about 0.6 x 10 6 cells per microliter to about 1.2 x 10 6 cells per microliter. In some embodiments, the therapeutically effective amount of the cellular composition is administered at a concentration of about 0.9 x 10 6 cells per microliter to about 1.2 x 10 6 cells per microliter. In some embodiments, the therapeutically effective amount of the cellular composition is administered at a concentration of about 1 x 10 6 cells per microliter.
  • a cellular composition such as the cellular compositions of pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells described herein (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells), having a high concentration of cells is delivered to a subject using a delivery device, such as, but not limited to, a cannula or catheter.
  • a delivery device such as, but not limited to, a cannula or catheter.
  • delivering a cellular composition such as the cellular compositions of pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells), to the subject involves loading the cellular composition from the proximal end of the delivery device (e.g., cannula) and displacing the cellular composition from the proximal end of the delivery device with a chase vehicle solution (e.g., a cell-free liquid chase vehicle), or inner stylet, such that the desired volume of the cellular composition is expelled from the delivery device outlet at the proximal end.
  • a chase vehicle solution e.g., a cell-free liquid chase vehicle
  • proximal refers to a position along the delivery device (e.g., cannula) that is closer to the subject to which the cellular composition is being delivered than a position that is “distal”.
  • a delivery device e.g., cannula
  • the cellular composition is loaded at the proximal portion of the delivery device (e.g., cannula) and a chase vehicle solution fills the rest of the internal compartment of the delivery device.
  • the chase vehicle solution includes the same pharmaceutically acceptable carrier as the cellular composition. In some embodiments, the chase vehicle solution is a cell-free liquid composition that includes the same pharmaceutically acceptable carrier as the cellular composition. In some embodiments, the chase vehicle solution (or liquid chase vehicle) is the same as the delivery vehicle in which the cellular composition is provided for administration to a subject, but in a cell-free format. In some embodiments, the chase vehicle solution has a lower viscosity than the cellular composition.
  • the delivery device e.g., cannula
  • a displacement device e.g., syringe or stylet traversing the inner lumen of the cannula
  • the chase vehicle is not required (e.g., where the cellular composition is displaced by a stylet positioned in the cannula and configured to push the cellular composition out of the proximal end of the cannula).
  • the displacement device is attached to a pump configured to drive the syringe plunger and thereby expel the cellular composition from the delivery device (e.g., cannula) in a controlled manner.
  • the cellular composition is stably held in the delivery device (e.g., cannula) for a sufficient period of time to allow delivery to the subject. For example, substantially all of the cells remain in the volume at the end or tip of the delivery device (e.g., cannula) at which the composition is initially placed for a suitable period of time before administering to a subject.
  • the cellular composition is stably held in the cannula, before administering to a subject, for about 0.5 hours or more, e.g., about 1 hour, about 2 hours, about 3 hours, about 4 hours, about 6 hours, about 8 hours, about 12 hours, about 18 hours, about 24 hours, about 36 hours, about 48 hours, about 72 hours, about 96 hours or longer, or for a length of time within a range defined by any two of the preceding values (e.g., 0.5-96 hours, 1-72 hour, 2-48 hours, 6-96 hours, etc.).
  • the cellular composition of the present disclosure has been cryopreserved before use.
  • the method includes obtaining cryopreserved cells that include the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) before administering.
  • the method includes thawing a cryopreserved cellular composition that contains the pluripotent stem cell-derived, MGE- type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) before administering.
  • MGE-type inhibitory e.g., GABAergic
  • the method includes thawing a cryopreserved cellular composition that contains the pluripotent stem cell-derived, MGE- type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived
  • the cellular composition may be cryopreserved for any suitable length of time, for example, at least 1 week, 2 weeks, 3 weeks, 1 month, 2 months, 3 months, 4 months, 6 months, 9 months, 12 months, 18 months, 2 years, 5 years or more, or a length of time defined by any two of the preceding values (e.g., 1 week – 5 years, 2 weeks – 2 years, 1 month – 1 year, or 6 months to 2 years, etc.), before the administering.
  • any suitable length of time for example, at least 1 week, 2 weeks, 3 weeks, 1 month, 2 months, 3 months, 4 months, 6 months, 9 months, 12 months, 18 months, 2 years, 5 years or more, or a length of time defined by any two of the preceding values (e.g., 1 week – 5 years, 2 weeks – 2 years, 1 month – 1 year, or 6 months to 2 years, etc.), before the administering.
  • the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells
  • MGE-type inhibitory neuron cells e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells
  • a cryopreservation formulation includes a cryoprotective agent, an energy substrate, and supplements, that prevent intracellular icicle formation (e.g., 0.5–20% DMSO (e.g., 0.5-1%, 1-2%, 2-5%, 5-10%, 10-15%, or 15-20% DMSO)), protect cell membranes by association with the cell surface, scavenge free radicals while providing pH buffering, oncotic/osmotic support, and stable ionic concentrations at low temperatures.
  • DMSO e.g., 0.5-1%, 1-2%, 2-5%, 5-10%, 10-15%, or 15-20% DMSO
  • the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells
  • MGE-type inhibitory neuron cells e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells
  • cryopreserving the cellular composition includes, before placing the cells in a cryoformulation that contains DMSO, incubating the cells in a buffer containing high molecular weight disaccharides, amino acids, and proteins such that cellular membrane structures are physically and chemically stable across a range of temperatures (e.g., 0-37°C, such as 4°C) and over a range of time periods in the buffer (e.g., 1 minute to 4 hours or more, such as overnight, including 30 minutes).
  • a range of temperatures e.g., 0-37°C, such as 4°C
  • time periods in the buffer e.g., 1 minute to 4 hours or more, such as overnight, including 30 minutes.
  • the cells are incubated in the buffer at about 0°C or higher, e.g., about 2 °C, about 4°C, about 6°C, about 10°C, about 12°C, about 15°C, about 18°C, about 20°C, about 25°C, about 30°C, or about 37°C, or at a temperature in a range defined by any two of the preceding values (e.g., 0-37°C, 2-30°C, 2-6°C, 10-30°C, 2-10°C, etc.).
  • cryopreserving the cells includes exposing the cells in the cryoformulation to an ambient temperature that is decreasing at a controlled rate, past the point of ice crystal nucleation, to about -20 to -80°C.
  • exposing the cells in the cryoformulation to an ambient temperature that is decreasing includes cooling the ambient temperature at a specified rate, such as about 0.5°C/min or faster, e.g., about 1°C/min, about 2°C/min, about 3°C/min, about 4°C/min, or about 5°C/min, or at a rate in a range defined by any two of the preceding values (e.g., 0.5-5°C/min, 0.5-2°C/min, 1- 4°C/min, 1-3°C/min, etc.).
  • a specified rate such as about 0.5°C/min or faster, e.g., about 1°C/min, about 2°C/min, about 3°C/min, about 4°C/min, or about 5°C/min, or at a rate in a range defined by any two of the preceding values (e.g., 0.5-5°C/min, 0.5-2°C/min, 1- 4°C/min, 1-3°C/min, etc.).
  • Exposing the cells in the cryoformulation to an ambient temperature that is decreasing at a controlled rate can be done using any suitable option, for example, without limitation, by placing the cells in a controlled rate freezer under conditions such that the ambient temperature is decreased at the controlled rate.
  • the cells after freezing, are stored at ⁇ -80°C, such as, without limitation, in liquid nitrogen vapor or liquid phase, e.g., at ⁇ -150°C.
  • the cryopreserved pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells are thawed by incubating the cryopreserved cells at 30-40°C (e.g., at, or at about 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40°C) for 0.5-5 minutes (e.g., for, or for about 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 minutes), and further rehydrating the cells for 0.5-2 minutes/mL (e.g., for, or for about 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, or 2 minutes/mL) in thaw medium.
  • MGE-type inhibitory neuron cells e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells
  • 0.5-5 minutes e.g., for
  • the thaw medium contains a nuclease (e.g., DNase), supplements and sodium ions, to scavenge free radicals while maintaining high osmolarity in order to reduce the risk of rapid cell expansion and cellular membrane damage.
  • a nuclease e.g., DNase
  • Any suitable nuclease can be used. Suitable nucleases include, without limitation, DNase I, Benzonase®, Micrococcal nuclease.
  • the thaw medium contains a nuclease (e.g., DNase) at about 500 units/mL or more, e.g., about 750 units/mL, about 1000 units/mL, about 1500 units/mL, about 2000 units/mL, or an amount in a range defined by any two of the preceding values (e.g., 500-2000 units/mL, 750- 1500 units/mL, 500-1000 units/mL, etc.).
  • a nuclease e.g., DNase
  • the thaw medium contains sodium ions at a concentration of, of about, or of at least 100, 150, 200, 250, 300, 350, 400, 450, 500, or 600 mM, or a concentration in a range defined by any two of the preceding values (e.g., 100-600 mM, 150-500 mM, 200-600 mM, 200-400 mM, 100-200 mM, etc.).
  • the thawed and rehydrated cells are further incubated before formulating in a delivery formulation.
  • the cells are incubated in a buffered solution that contains poloxamers, ions, and nutrients to facilitate cell membrane repair, restore intracellular electrochemical equilibrium, and maintain physiological pH balance.
  • Suitable poloxamers include, without limitation, P124, P188, P237, P338, and/or P407.
  • the buffered solution includes sodium chloride at a concentration of, of about, or of at least 100, 150, 200, 250, 300, 350, 400, 450, 500, or 600 mM, or a concentration in a range defined by any two of the preceding values (e.g., 100-600 mM, 150-500 mM, 200-600 mM, 200-400 mM, 100-200 mM, etc.).
  • the buffered solution includes sodium chloride at a concentration in a range of 100-600 mM.
  • the buffered solution includes sodium chloride at a concentration in a range of 200-600 mM.
  • the cells are incubated in a buffered solution that contains poloxamers, ions, and nutrients before administering to a subject, as described herein.
  • the cells can be incubated in the buffered solution at any suitable concentration, including at a high concentration while minimizing shear stress and reducing cell aggregation.
  • the cells are incubated in the buffered solution at a concentration of about 0.1 x 10 6 cells/ ⁇ L or higher, e.g., about 0.5 x 10 6 cells/mL, about 1 x 10 6 cells/mL, about 2 x 10 6 cells/mL, about 5 x 10 6 cells/mL, about 10 x 10 6 cells/mL, about 20 x 10 6 cells/mL, about 50 x 10 6 cells/mL, about 100 x 10 6 cells/mL, about 200 x 10 6 cells/mL, or about 300 x 10 6 cells/mL, or at a concentration in a range defined by any two of the preceding values (e.g., 0.1 x 10 6 cells/mL-300 x 10 6 cells/mL, 0.2 x 10 6 cells/mL-200 x 10 6 cells/mL, 0.5 x 10 6 cells/mL-100 x 10 6 cells/mL, 1 x 10 6 cells/mL- 300 x
  • the cells can be incubated in the buffered solution for any suitable time period (e.g., after thawing and rehydrating). In some embodiments, the cells are incubated in the buffered solution for about 0.5 hours or more, e.g., about 1 hour, about 2 hours, about 5 hours, about 10 hours, about 15 hours, about 20 hours, about 30 hours, or for a time period in a range defined by any two of the preceding values (e.g., 0.5-30 hours, 1-30 hours, 1-20 hours, 2-20 hours, 1-10 hours, etc.). The cells can be incubated in the buffered solution at any suitable temperature.
  • the cells are incubated in the buffered solution at about 0°C or higher, e.g., about 2 °C, about 4°C, about 6°C, about 10°C, about 12°C, about 15°C, about 18°C, about 20°C, about 25°C, or at a temperature in a range defined by any two of the preceding values (e.g., 0-25°C, 2- 25°C, 2-6°C, 10-20°C, 2-10°C, etc.).
  • the cells (with or without prior cryopreservation) can be further held or stored for a second time period before administering to a subject.
  • the cells can be further held or stored for a second time period, for example, for up to 1-7 days (e.g., 1, 2, 3, 4, 5, 6, 7 days, etc.) at 0-37°C (e.g., 4°C, 12°C, 20°C, 25°C, 37°C, etc.) before administering to a subject.
  • the cellular composition e.g., thawed cellular composition
  • the method includes holding (or storing) the cellular composition (e.g., thawed cellular composition) for 1-7 days (e.g., about 1, 2, 3, 4, 5, 6, or about 7 days, etc.) at 0-37°C (e.g., about 4°C, 12°C, 20°C, 25°C, or about 37°C, etc.) before administering to a subject.
  • the method includes holding (or storing) the cellular composition (e.g., thawed cellular composition) for up to about 5 days before administering to a subject.
  • the method includes holding (or storing) the cellular composition (e.g., thawed cellular composition) for up to about 5 days at about 4°C before administering to a subject. In some embodiments, the method includes holding (or storing) the cellular composition (e.g., thawed cellular composition) for up to about 7 days before administering to a subject. In some embodiments, the method includes holding (or storing) the cellular composition (e.g., thawed cellular composition) for up to about 7 days at about 4°C before administering to a subject.
  • the cellular composition e.g., thawed cellular composition
  • the method incudes holding the cells (e.g., thawed cells) at a temperature of, of about, or of at most 2, 4, 6, 8, 10, 12, 15, 17, 18, 19, 20, 21, 22, 25°C, or at a temperature in a range defined by any two of the preceding values (e.g., 4-25 °C, 4-20°C, 10- 20°C, 8-15°C, 4-12°C, 2-18°C, etc.), or at room temperature before administering to a subject.
  • the thawed cellular composition can be held (or stored) at any suitable stage between after thawing and delivering to the subject.
  • the cellular composition e.g., thawed cellular composition
  • a delivery device e.g., a cannula
  • a suitable compartment e.g., a tube, a syringe for attaching to a cannula, etc.
  • the cellular composition e.g., thawed cellular composition
  • the cells are further concentrated (e.g., before loading the cells into a delivery device, as described herein) to, to about, or to at least 0.1 x 10 6 cells per microliter (e.g., 0.1 x 10 6 -4 x 10 6 cells per microliter).
  • the cells are further concentrated and held or stored for the second time period in a suitable delivery vehicle, as described herein, before administering to the subject.
  • the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells e.g., pluripotent stem cell-derived, pallial, MGE- type GABAergic interneuron cells
  • the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells are a sorted population of cells differentiated from pluripotent stem cells.
  • the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells have been sorted (e.g., to enrich for the pallial or subpallial lineage) using one or more of flow cytometry, fluorescence activated cell sorting (FACS), or magnetic-activated cell sorting (MACS).
  • FACS fluorescence activated cell sorting
  • MCS magnetic-activated cell sorting
  • administration of the cellular composition reduces seizure frequency.
  • a method of the present disclosure provides for a reduction in the frequency of seizures by about 50% or more, about 55% or more, about 60% or more, about 65% or more, about 70% or more, about 75% or more, about 80% or more, about 85% or more, about 90% or more, about 95% or more, about 97% or more, about 99% or more, by about 100%, or by a percentage in a range defined by any two of the preceding values (e.g., 50-100%. 55-99%, 60-95%, 70-90%, or 75-95%, etc.), after administering the cellular composition.
  • administration of the cellular composition reduces the duration of seizure episodes.
  • a method of the present disclosure provides for a reduction in the duration of seizure episodes by about 50% or more, about 55% or more, about 60% or more, about 65% or more, about 70% or more, about 75% or more, about 80% or more, about 85% or more, about 90% or more, about 95% or more, about 97% or more, about 99% or more, or about 100%, or by a percentage in a range defined by any two of the preceding values (e.g., 50-100%. 55-99%, 60-95%, 70-90%, or 75- 95%, etc.), after administering the cellular composition.
  • administration of the cellular composition reduces seizure intensity (or severity).
  • the intensity (or severity) of seizures is reduced by about 20% or more, about 25% or more, about 30% or more, about 35% or more, about 40% or more, about 45% or more, about 50% or more, about 55% or more, about 60% or more, about 65% or more, about 70% or more, about 75% or more, about 80% or more, about 85% or more, about 90% or more, about 95% or more, about 97% or more, about 99% or more, or about 100%, or by a percentage in a range defined by any two of the preceding values (e.g., 50-100%. 55-99%, 60-95%, 70-90%, or 75-95%, etc.), after administering the cellular composition.
  • a percentage in a range defined by any two of the preceding values e.g., 50-100%. 55-99%, 60-95%, 70-90%, or 75-95%, etc.
  • seizure frequency, duration of seizure episodes, or seizure intensity (or severity) is determined based on a subjective assessment of the frequency of seizures, duration of seizure episodes, or intensity (or severity) of a seizure (e.g., the most severe seizure experienced in the last week, last month, etc.), respectively.
  • the seizure frequency, duration of seizure episodes, or seizure intensity (or severity) is determined based on a measurement of brain activity using, e.g., EEG, CT scan, MRI, fMRI, MRS, PET or SPECT before and/or after the administering.
  • administration of the cellular composition reduces spontaneous electrographic seizure activity in the subject.
  • co- administration of the cellular composition of the present disclosure with an anti-seizure medication may have a synergistic therapeutic effect.
  • a benzodiazepine anti-seizure medication may increase the affinity of the subject’s GABA receptors for GABA produced by the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE- type GABAergic interneuron cells).
  • co-administering two or more therapeutic agents to a subject includes administering a therapeutic agent such that the therapeutic agent effectively exhibits its therapeutic effect during any time interval in which one or more other therapeutic agent effectively exhibits their therapeutic effect.
  • co-administering can include administering one therapeutic agent before, at the same time as, or after administering a second therapeutic agent.
  • administration of the cellular composition reduces the dose of an anti-seizure medication, e.g., antiepileptic drug, required to treat the seizure in the subject.
  • administration of the cellular composition reduces the dose of an anti-seizure medication required to treat the seizure by about 20% or more, about 25% or more, about 30% or more, about 35% or more, about 40% or more, about 45% or more, about 50% or more, about 55% or more, about 60% or more, about 65% or more, about 70% or more, about 75% or more, about 80% or more, about 85% or more, about 90% or more, about 95% or more, about 97% or more, about 99% or more, or about 100%, or by a percentage in a range defined by any two of the preceding values (e.g., 20-100%, 25-99%, 30-95%, 30-90%, 40-90%, 50-80%, 60- 95%, 70-99%, etc.), after administering the cellular composition.
  • the preceding values e.g., 20-100%, 25-99%, 30-95%, 30-90%, 40-90%, 50-80%, 60- 95%, 70-99%, etc.
  • the patient does not require any further treatment with an anti-seizure medication, e.g., antiepileptic drug, for the seizure activity after administering the cellular composition to the subject.
  • an anti-seizure medication e.g., antiepileptic drug
  • a subject that is administered the cellular composition has about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95% or greater chance of reducing seizure frequency by 75% or more.
  • the therapeutic effect e.g., reduction in seizure frequency, reduction in sclerosis, and/or reduction in lesion size
  • the method includes measuring a therapeutic effect (e.g., reduction in seizure frequency, reduction in sclerosis, and/or reduction in lesion size) of administering the cellular composition to the subject.
  • administration of the cellular composition reduces tauopathy or one or more symptoms thereof (e.g., in a subject having AD).
  • the method includes detecting or measuring, e.g., non-invasively detecting or measuring, one or more therapeutic effects of administering the cellular composition to the subject.
  • the method includes measuring a reduction in seizure activity (e.g., seizure frequency and/or intensity) in the subject, as described herein.
  • the method includes using EEG to measure therapeutic effects of administering the cellular composition to the subject.
  • the method includes using one or more brain imaging techniques to measure one or more structural and/or metabolic changes in the subject’s brain indicative of a therapeutic effect of administering the cellular composition.
  • the method includes using one or more biomarkers of seizure activity to monitor, e.g., non- invasively monitor, the therapeutic effect.
  • the biomarkers of seizure activity include one or more blood-based biomarkers.
  • the method includes measuring the change in level of one or more of N-acetylaspartate (NAA), myoinositol, glutamate, ⁇ -Aminobutyric acid (GABA) in the subject’s brain or a region thereof.
  • NAA N-acetylaspartate
  • GABA ⁇ -Aminobutyric acid
  • the method includes measuring the level of one or more of N-acetylaspartate (NAA), myoinositol, glutamate, ⁇ -Aminobutyric acid (GABA) before and/or after administering the cellular composition.
  • NAA N-acetylaspartate
  • GABA ⁇ -Aminobutyric acid
  • MRS magnetic resonance spectroscopy
  • the method includes measuring the change in one or more of volume, edema, blood flow, oxygen metabolism and/or glucose levels in the subject’s brain or a region thereof.
  • the volume, edema, blood flow, oxygen metabolism and/or glucose levels can be measured using any suitable option.
  • the method includes using magnetic resonance imaging (MRI) and/or positron emission tomography (PET) to detect volume, edema, blood flow, oxygen metabolism and/or glucose levels in the subject’s brain or a region thereof.
  • the method includes measuring (e.g., non-invasively measuring) the therapeutic effect using one or more biomarkers of seizure activity.
  • ministration of the cellular composition reduces the extent of sclerosis or size of an epileptogenic lesion in the subject’s brain by about 5% or more, e.g., 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or about 100%, or by a percentage in range defined by any two of the preceding values (e.g., 5-100%, 10-90%, 20-50%, 50-90%, 40-70%, 80- 100%, etc.) compared to the extent of sclerosis or size of the lesion before administering.
  • the extent of sclerosis and/or size of the epileptogenic lesion can be determined using any suitable option.
  • Suitable options include, without limitation, CT scan, MRI, MRS, EEG, PET, SPECT, or fMRI.
  • the method includes using one or more of a CT scan, MRI, MRS, EEG, PET, SPECT, or fMRI to detect the presence and/or measure the size of an epileptogenic lesion in the subject’s brain, before and/or after administering the cellular composition.
  • the method includes using one or more of a CT scan, MRI, MRS, EEG, PET, SPECT, or fMRI before administering the cellular composition, e.g., for diagnosis and/or localizing an onset zone (e.g., a seizure or epileptogenic onset zone).
  • an onset zone e.g., a seizure or epileptogenic onset zone
  • the method includes using one or more of a CT scan, MRI, MRS, EEG, PET, SPECT, or fMRI after administering the cellular composition, e.g., to monitor therapeutic efficacy.
  • the method includes using one or more of a CT scan, MRI, MRS, EEG, PET, SPECT, or fMRI to determine a reduction in extent of sclerosis or size of an epileptogenic lesion in the subject’s brain after administering the cellular composition.
  • administration of the cellular composition increases or restores viable neurons in the subject’s brain or a region thereof.
  • the level of NAA correlates with viable neurons in the subject’s brain or a region thereof.
  • administration of the cellular composition increases the level of NAA in the subject’s brain or a region thereof. In some embodiments, administration of the cellular composition increases the level of NAA in the subject’s brain or a region thereof by about 5% or more, e.g., 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% or more, or by a percentage in a range defined by any two of the preceding values (e.g., 5-100%, 10-90%, 15-80%, 20-100%, 5-50%, 50-100%, etc.) relative to the level before administering.
  • the preceding values e.g., 5-100%, 10-90%, 15-80%, 20-100%, 5-50%, 50-100%, etc.
  • administration of the cellular composition restores the level of NAA in the subject’s brain or a region thereof to a level comparable to (e.g., within 30%, 20%, 10%, 5% of, or substantially the same as) the level in a healthy subject or a subject that is not suffering from seizure activity.
  • administration of the cellular composition reduces inflammation in the subject’s brain or a region thereof.
  • the level of myoinositol correlates with inflammation in the subject’s brain or a region thereof.
  • administration of the cellular composition reduces the level of myoinositol in the subject’s brain or a region thereof.
  • administration of the cellular composition reduces the level of myoinositol in the subject’s brain or a region thereof by about 5% or more, e.g., 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or about 100%, or by a percentage in a range defined by any two of the preceding values (e.g., 5-100%, 10-90%, 15-80%, 20-100%, 5-50%, 5-20%, etc.) relative to the level before administering.
  • the preceding values e.g., 5-100%, 10-90%, 15-80%, 20-100%, 5-50%, 5-20%, etc.
  • administration of the cellular composition restores the level of myoinositol in the subject’s brain or a region thereof to a level comparable to (e.g., within 30%, 20%, 10%, 5% of, or substantially the same as) the level in a healthy subject or a subject that is not suffering from seizure activity.
  • administration of the cellular composition reduces or restores neural excitation in the subject’s brain or a region thereof.
  • the level of glutamate correlates with inflammation in the subject’s brain or a region thereof.
  • administration of the cellular composition reduces the level of glutamate in the subject’s brain or a region thereof.
  • administration of the cellular composition reduces the level of glutamate in the subject’s brain or a region thereof by about 5% or more, e.g., 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or about 100%, or by a percentage in a range defined by any two of the preceding values (e.g., 5-100%, 10-90%, 15-80%, 20-100%, 5-50%, 5-20%, etc.) relative to the level before administering.
  • the preceding values e.g., 5-100%, 10-90%, 15-80%, 20-100%, 5-50%, 5-20%, etc.
  • administration of the cellular composition restores the level of glutamate in the subject’s brain or a region thereof to a level comparable to (e.g., within 30%, 20%, 10%, 5% of, or substantially the same as) the level in a healthy subject or a subject that is not suffering from seizure activity.
  • administration of the cellular composition restores GABAergic tone in the subject’s brain or a region thereof.
  • the level of GABA correlates with GABAergic tone in the subject’s brain or a region thereof.
  • administration of the cellular composition restores the level of GABA in the subject’s brain or a region thereof to a level comparable to (e.g., within 30%, 20%, 10%, 5% of, or substantially the same as) the level in a healthy subject or a subject that is not suffering from seizure activity.
  • the subject has a cognitive (or neurocognitive) impairment associated with the seizure activity.
  • the cognitive (or neurocognitive) impairment includes a memory impairment, including, without limitation, impairment in short-term memory, long-term memory, or working memory.
  • the memory impairment includes, without limitation, impairment in verbal and/or visuospatial memory.
  • the method includes performing one or more neurocognitive assessments of the subject before and/or after the administration. Any suitable neurocognitive assessment can be performed, including without limitation, tests for word retrieval, verbal memory, and/or visuospatial memory.
  • administration of the cellular composition ameliorates, reduces, or restores cognitive (or neurocognitive) impairment associated with the seizure activity in the subject.
  • administration of the cellular composition slows or prevents further deterioration of the neurocognitive capacity of the subject.
  • administration of the cellular composition at least partially restores the neurocognitive capacity of the subject to a level within a range of a healthy individual.
  • administration of the cellular composition at least partially improves the neurocognitive capacity of the subject compared to the level before administration.
  • administration of the cellular composition improves the quality of life of the subject.
  • the quality of life can be measured using any suitable option.
  • the subject’s self-assessment of quality of life is used to measure improvement before and after administration of the cellular composition.
  • administration of the cellular composition reduces the risk of death associated with the seizure activity and/or symptoms thereof.
  • Methods of the present disclosure can provide for delivery of, or transplanting, pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) to a host brain, where the cells are capable of functionally integrating into the endogenous host brain tissue.
  • pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells
  • about or at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.) of the administered cells persist in the host brain for, for about, or for at least 3, 6, 9, 12, 15, 18, 21, 24, 36, 48, 60, 72, months, or a period of time in a range defined by any two of the preceding values (e.g., 3-72 months, 6-60 months, 12-48 months, 6-12 months, etc.) after administration.
  • persistence or persistence rate denotes the percentage of transplanted cells that remain in the brain of the subject to whom the cellular composition has been administered, relative to the total number of cells administered.
  • the persistence rate of the administered cells in the host brain at 6 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15% , or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4- 8%, etc.).
  • the persistence rate of the administered cells in the host brain at 8 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.).
  • the persistence rate of the administered cells in the host brain at 10 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4- 10%, or 4-8%, etc.).
  • the persistence rate of the administered cells in the host brain at 12 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.).
  • the persistence rate of the administered cells in the host brain at 15 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1- 5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.).
  • the persistence rate of the administered cells in the host brain at 18 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.).
  • the persistence rate of the administered cells in the host brain at 24 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1- 15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.).
  • the persistence rate of the administered cells in the host brain at 36 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4- 10%, or 4-8%, etc.).
  • the persistence rate of the administered cells in the host brain at 48 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.).
  • about, or at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1- 5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.) of the administered cells functionally integrate into the subject’s brain as GABAergic neurons.
  • about or at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4- 8%, etc.) of the administered cells functionally integrate into the subject’s brain as GABAergic interneurons, e.g., where the administered composition includes pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells.
  • 3-15% of the administered cells functionally integrate into the subject’s brain as GABAergic interneurons, e.g., where the administered composition includes pluripotent stem cell- derived, pallial, MGE-type GABAergic interneuron cells.
  • about 3 % or more, 4% or more, 5% or more, 6% or more, 8% or more, 9% or more, 10% or more, or about 12% or more, or a percentage in a range defined by any two of the preceding values (e.g., 3-15%, 3-12%, 4-10%, or 4-8%, etc.) of the administered cells functionally integrate into the subject’s brain as GABAergic projection neurons, e.g., where the administered composition includes pluripotent stem cell-derived, subpallial, MGE-type GABAergic neuron cells.
  • the percentage of post-mitotic cells in the administered cellular composition is sufficiently high to result in a high percentage of the cells persisting in the transplanted brain retaining the MGE-type GABAergic neuron cell fate.
  • the cells of the cellular composition retain the pallial, MGE-type GABAergic interneuron cell fate after transplantation to the host brain.
  • the cells of the cellular composition retain the subpallial, MGE-type GABAergic neuron cell fate after transplantation to the host brain.
  • the high-percentage of post-mitotic cells in the administered cellular composition promotes a higher percentage of cells persisting in the transplanted brain that retain the MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate), for example, after, after about, or after at least 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 24, 36, 48, months, or a length of time in a range defined by any two of the preceding values (e.g., 3-48 months, 4-36 months, 6-24 months, 9-12 months, 12-48 months, etc.).
  • MGE-type GABAergic neuron cell fate e.g., pallial, MGE-type GABAergic interneuron cell fate
  • the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE- type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 55-95%, 60-85%, 90-98%, etc.) about 3 months or more after administration.
  • the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 55-95%, 60-85%, 90-98%, etc.) about 6 months or more after administration.
  • the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 55-95%, 60-85%, 90-98%, etc.) about 9 months or more after administration.
  • the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 55-95%, 60-85%, 90-98%, etc.) about 12 months or more after administration.
  • the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 55-95%, 60-85%, 90-98%, etc.) about 24 months or more after administration.
  • the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 55-95%, 60-85%, 90-98%, etc.) about 36 months or more after administration.
  • the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 55-95%, 60-85%, 90-98%, etc.) about 48 months or more after administration.
  • the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50%, about 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 years or more after administration. In some embodiments, the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is in the range of 50-90%, about 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 years or more after administration.
  • the cells persisting in the subject and that retain a pallial, MGE-type GABAergic interneuron cell fate express one or more of GAD1, GAD2, LHX6, SOX6, NXPH1, ERBB4, SST, NPY, MEF2c, and ARX.
  • expression of one or more markers of a pallial interneuron lineage indicates retention of a pallial interneuron cell fate in the persisting cells.
  • expression of one or more markers of a MGE-type lineage indicates retention of a MGE- type GABAergic neuron cell fate in the persisting cells.
  • expression of one or more markers of a GABAergic neuron lineage indicates retention of a GABAergic neuron cell fate in the persisting cells.
  • expression of one or more markers of a subpallial interneuron lineage indicates retention of a subpallial neuron cell fate in the persisting cells.
  • detecting electrophysiological properties of a GABAergic neuron indicates retention of a GABAergic neuron cell fate in the persisting cells.
  • the method includes administering one or more additional doses of the cellular composition to the subject after an initial administration of the therapeutically effective amount of the cellular composition.
  • the one or more additional doses is administered at about the same dose (e.g., same number of cells) as the initial dose.
  • the one or more additional doses is administered at a different dose (e.g., different number of cells) than the initial dose.
  • the therapeutically effective amount of the cellular composition in the one or more additional doses includes fewer cells than the number of cells in the therapeutically effective amount of the cellular composition in the initial dose. In some embodiments, the therapeutically effective amount of the cellular composition of the one or more additional doses includes at most about 100%, 95%, 90%, 80%, 70%. 60%, 50%, 40%, 30%, 20%, 10%, 5%, 1%, 0.1% or less, or a percentage in between any two of the preceding values (e.g., 0.1-100%, 1-95%, 5-90%, 10-80%, 10-70%, 20-60%, 30-50%, 10-50%, 10-30%, etc.), of the number of cells as the therapeutically effective amount of the cellular composition in the initial dose.
  • the therapeutically effective amount of the cellular composition of the one or more additional doses includes more cells than the number of cells in the therapeutically effective amount of the cellular composition in the initial dose.
  • the patient does not require any further administration of the cellular composition to treat the seizure activity after the initial dose.
  • the patient does not require any further treatment for the seizure activity after administering the cellular composition to the subject.
  • the method further includes co-administering an anti-seizure medication to the subject.
  • the co-administered anti-seizure medication can be administered before, after, or concurrently with the administration of the cellular composition.
  • the co-administered anti-seizure medication is one suitable for treating generalized seizure.
  • the anti-seizure medication can be administered using any suitable option.
  • administration is oral or parenteral.
  • administration is local or systemic.
  • administration is intravenous, intracranial, subcutaneous, intramuscular, intraperitoneal.
  • the anti-seizure medication includes one or more benzodiazepines.
  • Suitable anti-seizure medications include, without limitation, Carbamazepine, Cenobamate, Clobozam, Clonazepam, Diazepam, Ethosuximide, Felbamate, Fenfluramine, Gabapentin, Lacosamide, Lamotrigine, Levetiracetam, Lorazepam, Midazolam, Oxcarbazepine, Phenobarbital, Phenytoin, Pregabalin, Primidone, Tiagabine, Topiramate, Valproic acid, Vigabatrin, Zonisamide. [0143] In some embodiments, the method includes any suitable option to reduce or minimize adverse immunological reactions by the subject (e.g., immune-cloaking).
  • one or more immunosuppressants are co-administered to the subject.
  • immunosuppressants promote long-term engraftment of allogeneic or autologous cells. Any suitable immunosuppressant can be administered to a subject, e.g., to promote engraftment of the transplanted cells herein.
  • Suitable immunosuppressants include, without limitation, glucocorticosteroids (e.g., prednisolone, cortisone, prednisone, dexamethasone, etc.), calcineurin inhibitors (e.g., cyclosporin A, tacrolimus), and cytostatic agents (e.g., azathioprine, and mycophenolate mofetil (MMF)).
  • glucocorticosteroids e.g., prednisolone, cortisone, prednisone, dexamethasone, etc.
  • calcineurin inhibitors e.g., cyclosporin A, tacrolimus
  • cytostatic agents e.g., azathioprine, and mycophenolate mofetil (MMF)
  • one or more immunosuppressants are administered to the subject before, at the same time as, or after administering the cellular composition to the subject.
  • the method includes administering an immuno
  • the method includes gradually reducing the dose of the immunosuppressant after a time period post-administration.
  • the immunosuppressant can be administered to the subject at any suitable time period before administering the cellular composition to the subject.
  • the method includes administering an immunosuppressant to the subject for a time period of, of about, or of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 14, 17, 21, 24, or 28 days, or a number of days in a range defined by any two of the preceding values (e.g., 1-28 days, 2-24 days, 3-14 days, 4-10 days, etc.) before administering the cellular composition to the subject.
  • the immunosuppressant can be administered to the subject for any suitable time period after administering the cellular composition to the subject.
  • the method includes administering an immunosuppressant to the subject for a time period of, of about, or of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 17, 21, 24, or 28 months, or a number of days in a range defined by any two of the preceding values (e.g., 1-28 months, 2-24 months, 3-14 months, 4-12 months, etc.) after administering the cellular composition to the subject.
  • an immunosuppressant to the subject for a time period of, of about, or of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 17, 21, 24, or 28 months, or a number of days in a range defined by any two of the preceding values (e.g., 1-28 months, 2-24 months, 3-14 months, 4-12 months, etc.) after administering the cellular composition to the subject.
  • the method includes administering an initial dose of an immunosuppressant to the subject for an initial time period of, of about, or of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 17, 21, 24, or 28 months, or a number of days in a range defined by any two of the preceding values (e.g., 1-28 months, 2-24 months, 3-14 months, 4-12 months, etc.) after administering the cellular composition to the subject, and then reducing the dose after the initial time period.
  • an initial dose of an immunosuppressant to the subject for an initial time period of, of about, or of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 17, 21, 24, or 28 months, or a number of days in a range defined by any two of the preceding values (e.g., 1-28 months, 2-24 months, 3-14 months, 4-12 months, etc.) after administering the cellular composition to the subject, and then reducing the dose after the initial time period.
  • the method includes use of genetically modified pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells), as described herein, for example, to reduce an immunological response against the administered cellular composition by the subject.
  • the method includes immunosuppression by genetically modifying the interneurons, precursors, or pluripotent stem cells of the present disclosure.
  • the genetic modification contributes to evasion of the recipient's immune system by the transplanted or administered cells.
  • Any suitable gene that inhibits the expression or activity of immune-activating genes can be mutated to reduce or abolish activity, or knocked out, and/or any suitable genetic modification that activates expression or activity of immune-inhibiting genes can be made in the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells (or a precursor thereof).
  • the method includes genetically modifying one or more genes to reduce or abolish activity, and/or knocking out one or more immune-activating genes (e.g., B2M, a HLA class I gene, and/or a HLA class II gene, etc.) in the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells (or a precursor thereof).
  • the method includes genetically modifying the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells (or a precursor thereof) to activate expression or activity of immune-inhibiting genes.
  • the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells are genetically modified to reduce or abolish expression of one or more of: B2M, a HLA class I gene, and/or a HLA class II gene.
  • the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells are genetically modified to knock out one or more of: B2M, a HLA class I gene, and/or a HLA class II gene.
  • Genetically modifying the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells can be done using any suitable option for genetic modification and/or gene editing.
  • suitable options include, without limitation, viral infection (e.g., adeno-associated virus, adenovirus, herpes simplex virus, lentivirus, retrovirus, etc.), zinc finger nuclease, TALEN, CRISPR-Cas nuclease, etc.
  • a method of treating seizure activity comprising: identifying a subject in need of treating seizure activity; and intracranially administering to the subject a cellular composition comprising: about 5 x 10 4 to about 1 x 10 12 pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells at a concentration in a range of about 1 x 10 5 to about 4 x 10 6 cells/ ⁇ L, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1, wherein 90% or more of the cells of the composition are post-mitotic cells; a poloxamer at 0.1-1%, v/v; and sodium chloride at 100- 600 mM.
  • the cellular composition for use in the present disclosure generally includes pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells).
  • pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells.
  • the cellular composition is sufficiently enriched in the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) so as to provide a therapeutic result when administered in a therapeutically effective amount to a subject in need of treating seizure activity.
  • MGE-type inhibitory e.g., GABAergic
  • the cellular composition includes NRTX-1001 prepared by Neurona Therapeutics Inc.
  • the cellular composition is a composition enriched for MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells).
  • MGE-type inhibitory e.g., GABAergic
  • the combination of markers characteristic of MGE-type inhibitory (e.g., GABAergic) neuron cells includes at least LHX6 and GAD1.
  • about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the composition are MGE-type inhibitory (e.g., GABAergic) neuron cells.
  • MGE-type inhibitory e.g., GABAergic
  • about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50- 100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the composition are pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells.
  • at least 80% of the cells of the composition are pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells.
  • about 85% of the cells of the composition are pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells.
  • MGE-type inhibitory e.g., GABAergic
  • about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the composition express a combination of markers characteristic of pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells.
  • the combination of markers characteristic of pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells includes at least (i) LHX6, (ii) ERBB4, and (iii) GAD1.
  • the combination of markers characteristic of pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells includes at least two or more (e.g., any 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 or all) of: DLX6-AS1, GAD1, GAD2, LHX6, SST, SLC32A1, ARX, DLX1, DLX2, DLX5, MEF2C, ZEB2, SOX6, NXPH1, CXCR4, ACKR3, MAF, MAFB, and ERBB4.
  • the combination of markers characteristic of pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells includes at least (i) LHX6, (ii) ERBB4, (iii) GAD1, and optionally (iv) one or more of DLX6-AS1, GAD2, SST, SLC32A1, ARX, DLX1, DLX2, DLX5, MEF2C, ZEB2, SOX6, NXPH1, CXCR4, MAF, MAFB, and ACKR3.
  • At least 80% (e.g., about 80, 85, 90, 95% or more) of cells of the cellular composition express (i) LHX6, (ii) ERBB4, (iii) GAD1.
  • at least 50%, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or more, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the cellular composition further express at least one of MAF and MAFB.
  • 20-55% or 20-30% of cells of the cellular composition express SST.
  • the cells in the composition are characterized by expression (or lack thereof) of one or more markers in a manner consistent with the cell type of interest, such as pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells capable of integrating into the host brain upon transplantation.
  • a marker can refer to mRNA and/or protein expression.
  • the cellular composition is enriched for cells expressing two or more, or three or more, markers of a pallial, MGE-type inhibitory (e.g., GABAergic) interneuron lineage, as noted above.
  • the preceding values e.g., 45-100%, 50-100%, 50-80%, 60-90%, 75-100%, 80-100%, 85-98%, 90-95%, 90-100%, etc.
  • the cellular composition is enriched for cells expressing LHX6, ERBB4, and/or GAD1, compared to before being differentiated in vitro (e.g., embryonic stem cells) or compared to during the differentiation in vitro (e.g., MGE-type progenitor cells).
  • the cells of the cellular composition express two or more (e.g., any 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or all) markers for pallial, MGE-type inhibitory (e.g., GABAergic) interneurons selected from: DLX6-AS1, GAD1, GAD2, LHX6, SST, SLC32A1, ARX, DLX1, DLX2, DLX5, MEF2C, ZEB2, SOX6, NXPH1, CXCR4, ACKR3, MAF, MAFB, and ERBB4.
  • MGE-type inhibitory e.g., GABAergic
  • the cellular composition is enriched for cells expressing two or more (e.g., any 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or all) markers for GABAergic interneurons selected from: DLX6- AS1, GAD1, GAD2, LHX6, SST, SLC32A1, ARX, DLX1, DLX2, DLX5, MEF2C, ZEB2, SOX6, NXPH1, CXCR4, ACKR3, MAF, MAFB, and ERBB4, compared to before being differentiated in vitro (e.g., embryonic stem cells) or compared to during the differentiation in vitro (e.g., MGE-type progenitor cells).
  • two or more markers for GABAergic interneurons selected from: DLX6- AS1, GAD1, GAD2, LHX6, SST, SLC32A1, ARX, DLX1, DLX2, DLX5, MEF2C, ZEB2, SOX6, NXPH1, CXCR4, ACKR3, M
  • about, at least, or at least about 45% e.g., 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 97%, or about 100%, or a percentage within a range defined by any two of the preceding values (e.g., 45- 100%, 50-100%, 60-90%, 75-97%, 80-100%, 85-97%, 90-95%, 90-100%, etc.), of the cells of the cellular composition express two or more (e.g., any 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or all) markers for pallial, MGE-type inhibitory (e.g., GABAergic) interneurons selected from: DLX6-AS1, GAD1, GAD2, LHX6, SST, SLC32A1, ARX, DLX1, DLX2, DLX5, MEF2C, ZEB2, SOX6, NXPH1, CXCR4, ACKR3, MAF, MAFB, and ERBB
  • the cells of the cellular composition express one or more pan-neuronal markers selected from: DCX, MAPT, STMN2, C1orf61, and MAP2.
  • the cellular composition is depleted for cells expressing one or more markers that are indicative of an off-target cell type (e.g., a non- pallial, MGE-type inhibitory interneuron lineage).
  • an off-target cell type e.g., a non- pallial, MGE-type inhibitory interneuron lineage.
  • at most 20% of the cells of the composition are subpallial neurons. In some embodiments, at most 15% of the cells of the composition are subpallial neurons.
  • the cellular composition is depleted for cells expressing one or more off-target markers selected from LHX8, OTX2, SP8, ISL1, NKX2-1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2.
  • the cellular composition is depleted for cells expressing any of the off-target markers selected from LHX8, OTX2, SP8, ISL1, NKX2-1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2.
  • about 50% or less, e.g., 45%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 3%, 1%, or about 0%, or a percentage within a range defined by any two of the preceding values (e.g., 50-0%, 45-1%, 45-5%, 35-10%, 50-3%, etc.), of the cells of the cellular composition express one or more off-target markers selected from LHX8, OTX2, SP8, ISL1, NKX2-1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2.
  • about 50% or less, e.g., 45%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 3%, 1%, or about 0%, or a percentage within a range defined by any two of the preceding values (e.g., 50-0%, 45-1%, 45-5%, 35-10%, 50-3%, etc.), of the cells of the cellular composition express any of the off-target markers selected from LHX8, OTX2, SP8, ISL1, NKX2-1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2.
  • the cellular composition is depleted for cells expressing one or more markers for MGE-type progenitor cells selected from: LHX8, NKX2-1, and VIM, compared to during the differentiation in vitro (e.g., compared to MGE- type progenitor cells).
  • about or at most 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 2%, 1% or less, or a percentage in a range define by any two of the preceding values (e.g., 80-1%, 60-5%, 50- 10%, 80-20%, 75-20%, 70-25%, 65-30%, etc.) of cells of the cellular composition express LHX8.
  • the preceding values e.g., 45-100%, 50-100%, 50-80%, 60-90%, 75-100%, 80-100%, 85-98%, 90-95%, 90- 100%, etc.
  • about or at most 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 2%, 1% or less, or a percentage in a range define by any two of the preceding values (e.g., 80-1%, 60-5%, 50-10%, 80-20%, 75-20%, 70-25%, 65-30%, etc.) of cells of the cellular composition express NKX2-1.
  • the cellular composition is depleted for cells expressing one or more markers for glial cells selected from: SLC1A3, GFAP, OLIG1 and OLIG2, compared to before being differentiated in vitro (e.g., embryonic stem cells) or compared to during the differentiation in vitro (e.g., MGE-type progenitor cells).
  • about 5% or less, e.g., about 4%, about 3%, about 2%, about 1%, or about 0%, or a percentage in a range define by any two of the preceding values (e.g., 5-0%, 5-1%, 4- 1%, 3-1%, 5-2%, 4-2%, etc.) of cells of the cellular composition express OLIG2.
  • about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the composition are subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cells.
  • the subpallial, MGE-type GABAergic neuron cells include interneurons and/or projection neurons.
  • the combination of markers characteristic of a subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cell fate includes at least (i) LHX6, (ii) LHX8 and/or NKX2.1, and (iii) GAD1.
  • about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80- 100%, 85-95%, etc.) of the cells of the composition express at least LHX8 and/or NKX2.1.
  • a subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cell fate is characterized by a lack of ERBB4 expression.
  • the cellular composition is enriched for cells expressing two or more, or three or more, markers of a subpallial, MGE-type inhibitory (e.g., GABAergic) neuron lineage, as noted above.
  • the cellular composition is enriched for cells expressing LHX6, LHX8 and/or NKX2.1, and/or GAD1, compared to before being differentiated in vitro (e.g., embryonic stem cells) or compared to during the differentiation in vitro (e.g., MGE-type progenitor cells).
  • the cellular composition is depleted for cells expressing one or more markers that are indicative of an off-target cell type (e.g., a non-subpallial, MGE-type inhibitory neuron lineage).
  • an off-target cell type e.g., a non-subpallial, MGE-type inhibitory neuron lineage.
  • at most 20% of the cells of the composition are pallial interneurons. In some embodiments, at most 15% of the cells of the composition are pallial interneurons.
  • the cellular composition is depleted for cells expressing one or more off-target markers selected from ERBB4, MAF, MAFB, OTX2, SP8, ISL1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2.
  • off-target markers selected from ERBB4, MAF, MAFB, OTX2, SP8, ISL1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2.
  • about 50% or less, e.g., 45%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 3%, 1%, or about 0%, or a percentage within a range defined by any two of the preceding values (e.g., 50-0%, 45-1%, 45-5%, 35-10%, 50-3%, etc.), of the cells of the cellular composition express one or more off-target markers selected from ERBB4, MAF, MAFB, OTX2, SP8, ISL1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2.
  • about 50% or less, e.g., 45%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 3%, 1%, or about 0%, or a percentage within a range defined by any two of the preceding values (e.g., 50-0%, 45-1%, 45-5%, 35-10%, 50-3%, etc.), of the cells of the cellular composition express any of the off- target markers selected from ERBB4, MAF, MAFB, OTX2, SP8, ISL1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2.
  • about or at most 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 2%, 1% or less, or a percentage in a range define by any two of the preceding values (e.g., 80-1%, 60-5%, 50-10%, 80-20%, 75-20%, 70-25%, 65-30%, etc.) of cells of the cellular composition express ERBB4.
  • about or at most 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 2%, 1% or less, or a percentage in a range define by any two of the preceding values (e.g., 80-1%, 60-5%, 50-10%, 80-20%, 75-20%, 70-25%, 65-30%, etc.) of cells of the cellular composition express MAF and/or MAFB.
  • about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the composition express at least (i) LHX6, (ii) LHX8 and/or NKX2.1, and (iii) GAD1, and do not express ERBB4.
  • about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50- 100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the composition express at least (i) LHX6, (ii) LHX8 and/or NKX2.1, and (iii) GAD1, and do not express MAF or MAFB.
  • the percentage of cells expressing markers e.g., pallial, MGE-type interneuron markers (such as, without limitation, DLX6-AS1, GAD1, LHX6, SST, SLC32A1, ARX, DLX5, MEF2C, NXPH1, MAF, MAFB, and ERBB4), or non-pallial, MGE-type neuron markers in the cellular composition, can be determined, if desired, using any suitable option. In some embodiments, expression is determined by detecting a level of protein in the cells.
  • Suitable options for measuring expression level of a protein include, without limitation, ELISA, Western blotting, radioimmunoassay, immunoprecipitation, immunostaining (including, e.g., immunohistochemistry and immunocytochemistry), flow cytometry or fluorescence activated cell sorting (“FACS”) analysis, and homogeneous time- resolved fluorescence (HTRF) assays.
  • expression is determined by detecting a level of mRNA.
  • Suitable options for measuring expression level of a mRNA include, without limitation, Northern blot hybridization, ribonuclease RNA protection, in situ hybridization (ISH) (e.g., fluorescence in situ hybridization (FISH)), microarray analysis, reverse-transcription polymerase chain reaction (RT-PCR), high throughput or next generation sequencing.
  • ISH in situ hybridization
  • FISH fluorescence in situ hybridization
  • RT-PCR reverse-transcription polymerase chain reaction
  • the expression level of one marker is measured using an option that is different from that used to measure the expression level of another marker.
  • one marker can be measured using immunohistochemistry, and another marker can be measured using FACS.
  • one marker can be measured using immunohistochemistry, and another marker can be measured using ISH or FISH.
  • the expression level of one marker is measured using an option that is the same as that used to measure the expression level of another marker.
  • any one or more characteristics (e.g., marker expression, mitotic state, migratory capacity, etc.) of the cells of the composition can be determined, if desired, for at least a subset of the cells of the composition.
  • a representative portion or subset of the cells of the composition are assayed to determine one or more characteristics (e.g., marker expression, mitotic state, migratory capacity, etc.) of the cells of the composition.
  • substantially all cells of the composition do not contain or do not express an exogenous MGE-type progenitor cell marker.
  • the exogenous MGE-type progenitor cell marker can be any marker for MGE-type progenitor cells that is not native to the cells of the composition.
  • an exogenous MGE-type progenitor cell marker is a transgenic marker.
  • an exogenous MGE- type progenitor cell marker is an enhancer-promoter reporter gene, e.g., a fluorescent protein, such as a green fluorescent protein (GFP), expressed under an enhancer-promoter specific for MGE-type progenitor cell.
  • GFP green fluorescent protein
  • At most 30%, at most 20%, at most 15%, at most 10%, at most 5%, at most 3%, at most 2%, at most 1%, or about 0%, or at most a percentage in a range define by any two of the preceding values (e.g., at most 30-0%, at most 20-1%, at most 15-5%, at most 30-3%, etc.) of cells of the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) have an exogenous MGE-type progenitor cell marker.
  • MGE-type inhibitory e.g., GABAergic
  • substantially none of the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells has an exogenous MGE-type progenitor cell marker.
  • substantially all cells of the composition do not contain or express an exogenous marker.
  • the exogenous marker can be any marker that is not native to the cells of the composition.
  • an exogenous marker is a transgenic marker.
  • an exogenous marker is an enhancer-promoter reporter gene, e.g., a fluorescent protein, such as a green fluorescent protein (GFP), expressed under an enhancer-promoter.
  • a fluorescent protein such as a green fluorescent protein (GFP)
  • GFP green fluorescent protein
  • at most 30%, at most 20%, at most 15%, at most 10%, at most 5%, at most 3%, at most 2%, at most 1%, or about 0%, or at most a percentage in a range define by any two of the preceding values (e.g., at most 30-0%, at most 20-1%, at most 15-5%, at most 30-3%, etc.) of cells of the pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell- derived, pallial, MGE-type GABAergic interneuron cells) have an exogenous marker.
  • MGE-type inhibitory e.g.,
  • pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells e.g., pluripotent stem cell-derived, pallial, MGE- type GABAergic interneuron cells
  • MGE-type inhibitory neuron cells e.g., pluripotent stem cell-derived, pallial, MGE- type GABAergic interneuron cells
  • about 90% or more e.g., about 95% or more, about 97% or more, about 98% or more, about 98.5% or more, about 99% or more, about 99.5% or more, about 99.7% or more, about 99.8% or more, about 99.9% or more, about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 90-100%, 95-99%, 98-99.9%, 99-100%, etc.) of the cells of the composition are post-mitotic cells.
  • the percentage of post-mitotic cells in the composition can be determined using any suitable option, such as measuring incorporation of a nucleoside analog (e.g., BrdU or EdU), or measuring expression of a proliferation marker (e.g., KI67 and/or ASPM).
  • a nucleoside analog e.g., BrdU or EdU
  • a proliferation marker e.g., KI67 and/or ASPM
  • about 10% or less e.g., about 9% or less, about 8% or less, about 7% or less, about 6% or less, about 5% or less, about 4% or less, about 3% or less, about 2% or less, about 1% or less, about 0.5% or less, about 0.1% or less, about 0%, or a percentage in a range defined by any two of the preceding values (e.g., 10-0%, 8-0.1%, 5- 0.1%, 3-0.1%, 1-0.1%, 3-1%, 2-0.1%, 2-0%, etc.) of the cells of the cellular composition express KI67 and/or ASPM.
  • the cellular composition substantially lacks cells expressing one or more markers for cell cycling selected from: KI67 and ASPM. In some embodiments, 10% or less of the cells of the cellular composition express KI67 and/or ASPM. In some embodiments, 5% or less of the cells of the cellular composition express KI67 and/or ASPM. In some embodiments, 2% or less of the cells of the cellular composition express KI67 and/or ASPM. In some embodiments, 1% or less of the cells of the cellular composition express KI67 and/or ASPM. In some embodiments, 0.5% or less of the cells of the cellular composition express KI67 and/or ASPM.
  • about 10% or less e.g., about 9% or less, about 8% or less, about 7% or less, about 6% or less, about 5% or less, about 4% or less, about 3% or less, about 2% or less, about 1% or less, about 0.5% or less, about 0.1% or less, about 0%, or a percentage in a range defined by any two of the preceding values (e.g., 10-0%, 8-0.1%, 5-0.1%, 3-0.1%, 1-0.1%, 3-1%, 2-0.1%, 2- 0%, etc.) of the cells of the cellular composition incorporate a nucleoside analog (e.g., BrdU or EdU).
  • a nucleoside analog e.g., BrdU or EdU
  • the cellular composition substantially lacks cells that incorporate a nucleoside analog (e.g., BrdU or EdU).
  • a nucleoside analog e.g., BrdU or EdU.
  • Any suitable option can be used to increase the percentage of post-mitotic cells in the cellular composition.
  • an agent that promotes cell cycle exit and differentiation is used to increase the percentage of post-mitotic cells in the cellular composition.
  • a suitable agent that promotes cell cycle exit and differentiation includes, without limitation, an inhibitor of Notch signaling.
  • Suitable inhibitors of Notch signaling include, without limitation, a ⁇ -secretase inhibitor.
  • Suitable ⁇ -secretase inhibitors include, without limitation, DAPT, BMS906024, BMS986115, E-2012, avagacestat, nirogacestat, begacestat, semagacestat, MK-0752, tarenflurbil, RG-4733, PF 3084014, hydrobromid, CultureOne, Compound E, and itanapraced.
  • the Notch inhibitor is DAPT.
  • the percentage of post-mitotic cells among the cells of the cellular composition is increased by providing the inhibitor of Notch signaling to the culture for at least about the last week, e.g., the last 1.5 weeks, the last 2 weeks, or the last 2.5 weeks, of differentiation of the pluripotent stem cells into the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells).
  • MGE-type inhibitory e.g., GABAergic
  • neuron cells e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells.
  • cells of the cellular composition are migratory cells.
  • about 5% or more, e.g., about 7% or more, about 10% or more, about 15% or more, about 20% or more, about 25% or more, about 30% or more, or a percentage in a range defined by any two of the preceding values (e.g., 5-30%, 7-25%, 10- 30%, 15-25%, etc.) of the cells of the composition are migratory cells, e.g., as determined by an in vitro migration assay.
  • the proportion of migratory cells among cells of the cellular composition is at least 50%, e.g., 60%, 70%, 80%, 90%, 100%, 120%, 150%, 175%, 200%, 250%, 300% or more, or a percentage in a range defined by any two of the preceding values (e.g., 50-300%, 60-250%, 70-200%, 100-200%, 120-175%, 100-300%, etc.) of the proportion of migratory cells among primary human MGE interneurons, e.g., as determined by an in vitro migration assay.
  • the cellular composition comprises GABAergic cells.
  • the cellular composition comprises GABA-secreting cells.
  • GABA secretion and/or amount of GABA secretion can be detected using any suitable assay, such as an in vitro GABA release assay.
  • cells of the cellular composition secrete GABA in an in vitro GABA release assay.
  • cells of the cellular composition secrete GABA constitutively in an in vitro GABA release assay.
  • cells of the cellular composition increase GABA secretion upon stimulation, e.g., by potassium chloride, sodium chloride or other salt solution, in an in vitro GABA release assay.
  • the MGE-type inhibitory (e.g., GABAergic) neuron cells e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells
  • the MGE-type inhibitory (e.g., GABAergic) neuron cells can be cells derived from any suitable PS cells.
  • Suitable PS cells include, without limitation, embryonic stem cells (ESC) and induced pluripotent stem cells (iPS cells).
  • the MGE-type inhibitory (e.g., GABAergic) neuron cells are derived from neural stem cells.
  • the MGE-type inhibitory (e.g., GABAergic) neuron cells e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells
  • the MGE-type inhibitory (e.g., GABAergic) neuron cells are obtained through reprogramming or transdifferentiation of cells, e.g., somatic cells, neural cells obtained from the MGE, Cortex, Sub-Cortex, other regions of the brain, or non- neural cells.
  • the cellular composition for use in the present methods can be obtained using any suitable option.
  • a cellular composition is obtained by differentiating pluripotent stem cells, e.g., from ESCs or iPS cells, into the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells).
  • MGE-type inhibitory e.g., GABAergic
  • neuron cells e.g., pallial, MGE-type GABAergic interneuron cells.
  • the MGE-type inhibitory (e.g., GABAergic) neuron cells are derived from embryonic stem (ES) cells (e.g., hESCs) or induced pluripotent stem (iPS) cells.
  • ES embryonic stem
  • iPS induced pluripotent stem
  • the pluripotent stem cells are expanded before differentiating.
  • the pluripotent stem cells are expanded for, for about, or for at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14 days, or at least 3, 4, 5, 6, 7, or 8 weeks, or for a length of time in a range defined by any two of the preceding values (e.g., 1-8 weeks, 1-14 days, 2-10 days, 3-10 days, 3-7 days, etc.).
  • the pluripotent stem cells are expanded for about 5 days.
  • the pluripotent stem cells after expanding retain or substantially retain their pluripotency.
  • the pluripotent stem cells maintain expression of one or more markers of pluripotent stem cells after expanding. In some embodiments, the pluripotent stem cells exhibit a similar or substantially the same pattern of expression of one or more markers of pluripotent stem cells after expanding compared to the pattern of expression before expanding. In some embodiments, the markers of pluripotent stem cells include one or more of OCT4, NANOG, TRA1-60, and SSEA3/4. In some embodiments, the pluripotent stem cells maintain expression of OCT4, NANOG, TRA1-60, and SSEA3/4 after expanding. In some embodiments, the expanded pluripotent stem cells are OCT4+, NANOG+, TRA1-60+, and SSEA3/4+.
  • expanding the pluripotent stem cells includes culturing the cells in the presence of an FGF2 and/or TGF ⁇ signaling activator.
  • the TGF ⁇ signaling activator includes a SMAD signaling activator.
  • the SMAD signaling activator includes, without limitation, TGFs (e.g., TGF ⁇ 3), BMPs (e.g., BMP2, BMP4, BMP8), Activin, Nodal, GDF, and IDE1.
  • the FGF2 signaling activator includes FGF2.
  • Any suitable option for differentiating a population of pluripotent stem cells in vitro into a MGE-type neuron lineage can be used, e.g., as provided herein.
  • differentiating the population of pluripotent stem cells into the MGE-type neuron lineage includes culturing a population, or a differentiating population, of pluripotent stem cells in the presence of one or more of a sonic hedgehog (shh) signaling activator, a SMAD signaling inhibitor, a wnt signaling inhibitor, a bone morphogenetic protein (BMP) signaling inhibitor, a neural inducing supplement, a Rho- associated kinase (ROCK) signaling inhibitor, MEK signaling inhibitor, CDK signaling inhibitor, and a Notch signaling inhibitor.
  • a sonic hedgehog (shh) signaling activator a sonic hedgehog (shh) signaling activator
  • SMAD SMAD signaling inhibitor
  • wnt signaling inhibitor a wnt signaling inhibitor
  • BMP bone morphogenetic protein
  • a neural inducing supplement a Rho- associated kinase (ROCK) signaling inhibitor
  • a differentiating population of pluripotent stem cells refers to cells that are in the process of developing features of a cell lineage of interest, starting from the pluripotent stem cells.
  • cells of the differentiating population may have one or more features characteristic of the pluripotent stem cells and one or more features characteristic of the cell lineage of interest.
  • a population of pluripotent stem cells that are differentiating into a MGE-type neuron lineage includes MGE-type progenitor cells.
  • differentiating the population of pluripotent stem cells includes supplementing a culture of pluripotent stem cells with one or more of a sonic hedgehog (shh) signaling activator, a SMAD signaling inhibitor, a wnt signaling inhibitor, a bone morphogenetic protein (BMP) signaling inhibitor, a neural inducing supplement, a Rho- associated kinase (ROCK) signaling inhibitor, MEK signaling inhibitor, CDK signaling inhibitor, and a Notch signaling inhibitor.
  • a sonic hedgehog (shh) signaling activator e.g., a sonic hedgehog (shh) signaling activator
  • SMAD sonic hedgehog
  • wnt signaling inhibitor e.g., a wnt signaling inhibitor
  • BMP bone morphogenetic protein
  • a neural inducing supplement e.g., a Rho- associated kinase (ROCK) signaling inhibitor, MEK signaling inhibitor,
  • each of the one or more of a sonic hedgehog (shh) signaling activator, a SMAD signaling inhibitor, a wnt signaling inhibitor, a BMP signaling inhibitor, a neural inducing supplement, a ROCK signaling inhibitor, a MEK signaling inhibitor, a CDK signaling inhibitor, and a Notch signaling inhibitor is present in the culture during a time period that spans at least a portion of the differentiation process.
  • the culture of pluripotent stem cells is a serum-free culture. In some embodiments, the culture of pluripotent stem cells is a feeder cell-free culture.
  • the culture of pluripotent stem cells includes a feeder cell, e.g., a human feeder cell. Any suitable feeder cell can be used to culture the pluripotent stem cells in the presence of feeder cells. In some embodiments, the culture of pluripotent stem cells is a xeno-free culture.
  • differentiating the population of pluripotent stem cells includes a first time period (e.g., to promote definitive neuroectoderm specification and MGE patterning), a second time period following the first time period (e.g., to promote MGE progenitor expansion and pallial interneuron (or subpallial neuron) commitment), and a third time period following the second time period (e.g., to promote cell cycle exit and differentiation).
  • differentiating the population of pluripotent stem cells includes culturing the cells in a suitable base medium during the differentiation time course. Any suitable based medium can be used.
  • the base medium includes without limitation, MEM, DMEM, DMEM-F12, L-15, neurobasal medium, and combinations thereof.
  • the base medium includes a supplement for neuronal cell culture. Any suitable supplement for neuronal cell culture can be used for differentiating pluripotent stem cells.
  • the neural inducing supplement is, without limitation, B-27 TM (with or without vitamin A), NS21, N2 supplement-B, or an equivalent supplement, and combinations thereof.
  • the base medium includes amino acids.
  • differentiating the population of pluripotent stem cells includes culturing the pluripotent stem cells (e.g., hESCs) in the presence of one or more MGE patterning factors, including a ROCK signaling inhibitor, BMP signaling inhibitor, a TGF- ⁇ signaling inhibitor, a wnt signaling inhibitor, and a shh signaling activator during at least a portion of the first time period.
  • the first time period is, is about, or is at least 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or 21 days, or a length of time in a range defined by any two of the preceding values (e.g., 7-21 days, 10-18 days, 12-16 days, etc.).
  • the first time period is or is about 2 weeks.
  • the one or more MGE patterning factors are removed from the culture at the end of the first time period.
  • each of the MGE patterning factors are added to the culture for any suitable portion of the first time period to promote definitive neuroectoderm specification and MGE patterning.
  • one or more of the MGE patterning factors are added to the culture at the start of the first time period (e.g., D0 of the differentiation time course).
  • the differentiation time course denotes the number of days of the differentiation process starting from the pluripotent stem cells (after and excluding any stem cell expansion stage noted above).
  • one or more of the MGE patterning factors are added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the first time period (e.g., D1, D2, D3, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14 or later of the differentiation time course).
  • the cells are cultured in the presence of one or more of the MGE patterning factors for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the first time period.
  • the cells are cultured in the presence of one or more of the MGE patterning factors between D0-D14, D0- D7, D1-D7, D1-D14, D2-D5, D2-D7, D7-D12, or D7-D14 of the differentiation time course.
  • MGE patterning factors can be used to promote definitive neuroectoderm specification and MGE patterning.
  • each of the one or more MGE patterning factors is provided in the culture medium independently at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 ⁇ M, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 ⁇ M, 50 nM-100 ⁇ M, 100 nM- 100 ⁇ M, or 100 nM-50 ⁇ M).
  • differentiating the population of pluripotent stem cells further includes culturing the pluripotent stem cells (e.g., hESCs) in the presence of a FGF/VEGF/PDGF inhibitor (e.g., a receptor tyrosine kinase (RTK) inhibitor) during at least a portion of the first time period.
  • a FGF/VEGF/PDGF inhibitor e.g., a receptor tyrosine kinase (RTK) inhibitor
  • RTK receptor tyrosine kinase
  • the FGF/VEGF/PDGF inhibitor is, without limitation, SU5402, SU6668, BIBF1120, ZM323881, SU11652, or XL999.
  • the first time period may be referred to as the “MGE patterning” phase).
  • the population of cells (e.g., differentiating cells) that have been cultured for the first time period e.g., MGE patterned cells
  • the population of cells (e.g., differentiating cells) that have been cultured for the first time period is depleted for cells expressing PAX6.
  • the cells (e.g., differentiating cells) that have been cultured for the first time period are SOX1+, FOXG1+, NKX2-1+, and PAX6-.
  • the shh signaling activator can be any suitable activator of shh signaling.
  • the shh signaling activator includes, without limitation, shh or a derivative thereof, purmorphamine, SAG smoothened agonist, Hh-Ag1.5, or derivatives and analogs thereof.
  • the shh signaling activator includes SAG.
  • the shh signaling activator is added to the culture at the start of the first time period (e.g., D0 of the differentiation time course). In some embodiments, the shh signaling activator is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the first time period (e.g., D1, D2, D3, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14 or later of the differentiation time course).
  • the cells are cultured in the presence of the shh signaling activator for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1- 14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the first time period.
  • the cells are cultured in the presence of the shh signaling activator between D0-D14, D0-D7, D1-D7, D1-D14, D2-D5, D2-D7, D7-D12, or D7-D14 of the differentiation time course.
  • the shh signaling activator is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 ⁇ M, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 ⁇ M, 50 nM-100 ⁇ M, 100 nM-100 ⁇ M, or 100 nM-50 ⁇ M).
  • the shh signaling activator is provided in the culture medium at a concentration of or of about 100 nM.
  • Any suitable inhibitor or activator of SMAD signaling can be used for differentiating pluripotent stem cells.
  • the SMAD signaling modulator is a SMAD signaling inhibitor, such as, without limitation, TGF- ⁇ inhibitor, BMP inhibitor, Activin inhibitor, Nodal inhibitor, or GDF signaling pathway inhibitor.
  • the SMAD signaling inhibitor includes a TGF- ⁇ inhibitor.
  • the TGF- ⁇ inhibitor includes, without limitation, SB431542, Galunisertib, LDN-193189, and/or K02288.
  • the TGF- ⁇ inhibitor includes SB431542.
  • the TGF- ⁇ inhibitor is added to the culture at the start of the first time period (e.g., D0 of the differentiation time course).
  • the TGF- ⁇ inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the first time period (e.g., D1, D2, D3, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14 or later of the differentiation time course).
  • the cells are cultured in the presence of the TGF- ⁇ inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the first time period.
  • the cells are cultured in the presence of the TGF- ⁇ inhibitor between D0- D14, D0-D7, D1-D7, D1-D14, D2-D5, D2-D7, D7-D12, or D7-D14 of the differentiation time course. Any suitable amount of the TGF- ⁇ inhibitor can be used to promote definitive neuroectoderm specification and MGE patterning.
  • the TGF- ⁇ inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 ⁇ M, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 ⁇ M, 50 nM-100 ⁇ M, 100 nM-100 ⁇ M, or 100 nM-50 ⁇ M). In some embodiments, the TGF- ⁇ inhibitor is provided in the culture medium at a concentration of or of about 10 ⁇ M.
  • the BMP signaling inhibitor includes, without limitation, LDN193189, M4K2163, Dorsomorphin, DMH-1, and/or ML 347. In some embodiments, the BMP signaling inhibitor includes LDN193189. In some embodiments, the BMP signaling inhibitor is added to the culture at the start of the first time period (e.g., D0 of the differentiation time course).
  • the BMP signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the first time period (e.g., D1, D2, D3, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14 or later of the differentiation time course).
  • the cells are cultured in the presence of the BMP signaling inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the first time period.
  • the cells are cultured in the presence of the SMAD signaling inhibitor between D0-D14, D0-D7, D1-D7, D1-D14, D2-D5, D2-D7, D7-D12, or D7-D14 of the differentiation time course.
  • the SMAD signaling inhibitor can be used to promote definitive neuroectoderm specification and MGE patterning.
  • the BMP signaling inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 ⁇ M, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 ⁇ M, 50 nM-100 ⁇ M, 100 nM-100 ⁇ M, or 100 nM-50 ⁇ M). In some embodiments, the BMP signaling inhibitor is provided in the culture medium at a concentration of or of about 10 ⁇ M.
  • the wnt signaling inhibitor includes, without limitation, soluble frizzled polypeptides comprising the wnt binding domains; soluble frizzled related polypeptides; wnt specific antibodies; frizzled specific antibodies; and other molecules capable of blocking extracellular wnt signaling; Dkk gene family such as, but not limited to, Dkk-1, Dkk-2, Dkk-3, and Dkk-4, and the Dkk-3 related protein Soggy (Sgy); Wise; or a small molecule inhibitor, such as, but not limited to CKI-7, IWP analogs, IWR analogs, XAV939, 53AH, Wnt-C59.
  • the wnt signaling inhibitor includes XAV939. In some embodiments, the wnt signaling inhibitor is added to the culture at the start of the first time period (e.g., D0 of the differentiation time course). In some embodiments, the wnt signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the first time period (e.g., D1, D2, D3, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14 or later of the differentiation time course).
  • the start of the first time period e.g., D0 of the differentiation time course
  • the wnt signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the first time period (e.g., D1, D2, D3, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14 or later of the differentiation time course).
  • the cells are cultured in the presence of the wnt signaling inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the first time period.
  • the cells are cultured in the presence of the wnt signaling inhibitor between D0-D14, D0-D7, D1-D7, D1-D14, D2-D5, D2-D7, D7- D12, or D7-D14 of the differentiation time course.
  • the wnt signaling inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 ⁇ M, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 ⁇ M, 50 nM-100 ⁇ M, 100 nM- 100 ⁇ M, or 100 nM-50 ⁇ M).
  • the wnt signaling inhibitor is provided in the culture medium at a concentration of or of about 10 ⁇ M.
  • Any suitable inhibitor of ROCK signaling can be used for differentiating pluripotent stem cells.
  • the ROCK signaling inhibitor includes, without limitation, Y27623, thiazovivin, fasudil, ripasudil, or KD025.
  • the ROCK signaling inhibitor includes Y27623.
  • the ROCK signaling inhibitor is added to the culture at the start of the first time period (e.g., D0 of the differentiation time course).
  • the ROCK signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the first time period (e.g., D1, D2, D3, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14 or later of the differentiation time course).
  • the cells are cultured in the presence of the ROCK signaling inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the first time period.
  • the cells are cultured in the presence of the ROCK signaling inhibitor between D0-D14, D0-D7, D1-D7, D1-D14, D2-D5, D2-D7, D7-D12, or D7-D14 of the differentiation time course.
  • the ROCK signaling inhibitor can be used to promote definitive neuroectoderm specification and MGE patterning.
  • the ROCK signaling inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 ⁇ M, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 ⁇ M, 50 nM-100 ⁇ M, 100 nM-100 ⁇ M, or 100 nM-50 ⁇ M). In some embodiments, the ROCK signaling inhibitor is provided in the culture medium at a concentration of or of about 10 ⁇ M.
  • differentiating the population of pluripotent stem cells includes further culturing the cells (e.g., differentiating cells) that have been cultured for the first time period (e.g., MGE patterned cells), in the presence of a MEK signaling inhibitor during at least a portion of the second time period.
  • the second time period is, is about, or is at least 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28 days, or a length of time in a range defined by any two of the preceding values (e.g., 7-28 days, 7-21 days, 10-18 days, 12-16 days, etc.).
  • the second time period is or is about 2 weeks.
  • the cells are cultured without the signaling inhibitors (e.g., MEK signaling inhibitor) or activators as described herein during a portion (e.g., at the start) of the second time period.
  • the cells are cultured without the MEK signaling inhibitor during a portion (e.g., at the start) of the second time period.
  • the MEK signaling inhibitor is removed from the culture at the end of the second time period.
  • culturing the cells (e.g., differentiating cells) during the second time period can promote MGE progenitor expansion and pallial interneuron commitment.
  • the second time period may be referred to as the “expansion and commitment” phase).
  • the population of cells (e.g., differentiating cells) that have been cultured for the second time period is enriched for cells expressing LHX8 and/or LHX6.
  • the population of cells (e.g., differentiating cells) that have been cultured for the second time period is depleted for cells expressing high levels of NKX2-1, e.g., NKX2-1 expressed at levels expressed by MGE precursor cells.
  • the cells (e.g., differentiating cells) that have been cultured for the second time period are LHX8+, and have declining NKX2-1 expression and increasing LHX6 expression.
  • NKX2.1 continues to be expressed.
  • culturing the cells (e.g., differentiating cells) during the second time period can promote MGE progenitor expansion and subpallial neuron commitment (e.g., by omitting the MEK signaling inhibitor).
  • Any suitable inhibitor of MEK signaling can be used for differentiating pluripotent stem cells into a pallial interneuron lineage.
  • the MEK signaling inhibitor includes, without limitation, PD0325901. In some embodiments, the MEK signaling inhibitor includes PD0325901. In some embodiments, the MEK signaling inhibitor is added to the culture at the start of the second time period (e.g., around D14 of the differentiation time course). In some embodiments, the MEK signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the second time period (e.g., D14, D15, D16, D17, D18, D19, D20, D21, D22, D23, D24, D25, D26, D27, D28 or later of the differentiation time course).
  • the cells are cultured in the presence of the MEK signaling inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the second time period.
  • the cells are cultured in the presence of the MEK signaling inhibitor between D14-D28, D14-D21, D15-D21, D15-D28, or D21-D28 of the differentiation time course. Any suitable amount of the MEK signaling inhibitor can be used to promote MGE progenitor expansion and pallial interneuron commitment.
  • the MEK signaling inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 2, 5, 10, 20, 50, 100, or 200 ⁇ M, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 ⁇ M, 50 nM-100 ⁇ M, 100 nM- 100 ⁇ M, or 100 nM-50 ⁇ M). In some embodiments, the MEK signaling inhibitor is provided in the culture medium at a concentration of, or of about 2 ⁇ M.
  • differentiating the population of pluripotent stem cells includes further culturing the cells (e.g., differentiating cells) that have been cultured for the second time period (e.g., expanded and committed cells), in the presence of one or more cell cycle exit and differentiation factors, including a MEK signaling inhibitor, a CDK signaling inhibitor, and a Notch signaling inhibitor during at least a portion of the third time period.
  • the third time period is, is about, or is at least 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or 21 days, or a length of time in a range defined by any two of the preceding values (e.g., 7-21 days, 10-18 days, 12-16 days, etc.).
  • the third time period is or is about 2 weeks.
  • the one or more cell cycle exit and differentiation factors are removed from the culture at the end of the third time period.
  • each of the cell cycle exit and differentiation factors are added to the culture for any suitable portion of the third time period to promote cell cycle exit and differentiation.
  • one or more of the cell cycle exit and differentiation factors are added to the culture at the start of the third time period (e.g., around D28 of the differentiation time course).
  • one or more of the cell cycle exit and differentiation factors are added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the third time period (e.g., D28, D29, D30, D31, D32, D33, D34, D35, D36, D37, D38, D39, D40 or later of the differentiation time course).
  • the cells are cultured in the presence of one or more of the cell cycle exit and differentiation factors for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the third time period.
  • the cells are cultured in the presence of one or more of the cell cycle exit and differentiation factors between D28-D42, D28-D35, D29-D35, D29-D42, D30-D33, D30- D35, D35-D42, or D35-D40 of the differentiation time course.
  • each of the one or more cell cycle exit and differentiation factors is provided in the culture medium independently at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 ⁇ M, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 ⁇ M, 50 nM-100 ⁇ M, 100 nM-100 ⁇ M, or 100 nM-50 ⁇ M).
  • culturing the cells (e.g., differentiating cells) during the third time period promotes cell cycle exit and differentiation.
  • the third time period may be referred to as “cell cycle exit” phase).
  • the differentiated cells after culturing in the first, second and third time periods may be referred to as end-of-process (EOP) neurons.
  • the population of EOP neurons is enriched for cells expressing one or more of LHX6, GAD1, and ERBB4/CXCR4.
  • obtaining the cellular composition for use in the present methods includes enriching the differentiated cells for cells expressing one or more of LHX6, GAD1, and ERBB4/CXCR4/CXCR7.
  • enriching the differentiated cells includes using a binding moiety (e.g., antibody) that specifically binds to ERBB4 or CXCR4 or CXCR7, e.g., using FACS or MACS.
  • the population of EOP neurons is depleted for cells expressing LHX8 and/or NKX2-1.
  • the EOP neurons are LHX6+, GAD1+, ERBB4+/CXCR4+/CXCR7+, LHX8- and NKX2-1-.
  • Any suitable agent that inhibits Notch signaling can be used during the differentiation process for obtaining the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells).
  • the Notch signaling inhibitor includes, a ⁇ -secretase inhibitor.
  • the Notch signaling inhibitor includes, without limitation, DAPT, BMS906024, BMS986115, E-2012, avagacestat, nirogacestat, begacestat, semagacestat, MK-0752, tarenflurbil, RG-4733, itanapraced, PF3084014, and/or Culture One.
  • the Notch signaling inhibitor is added to the culture at the start of the third time period (e.g., around D28 of the differentiation time course).
  • the Notch signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the third time period (e.g., D28, D29, D30, D31, D32, D33, D34, D35, D36, D37, D38, D39, D40 or later of the differentiation time course).
  • the cells are cultured in the presence of the Notch signaling inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the third time period.
  • the cells are cultured in the presence of the Notch signaling inhibitor between D28-D42, D28-D35, D29-D35, D29-D42, D30-D33, D30-D35, D35-D42, or D35-D40 of the differentiation time course.
  • the Notch signaling inhibitor can be used to promote cell cycle exit and differentiation.
  • the Notch signaling inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 ⁇ M, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 ⁇ M, 50 nM-100 ⁇ M, 100 nM-100 ⁇ M, or 100 nM-50 ⁇ M). In some embodiments, the Notch signaling inhibitor is provided in the culture medium at a concentration of or of about 10 ⁇ M.
  • differentiating the population of pluripotent stem cells into the MGE-type neuron lineage includes culturing the differentiating population of pluripotent stem cells in the presence of a NOTCH signaling inhibitor for a time period after obtaining MGE-like progenitor cells.
  • differentiating pluripotent stem cells to obtain the pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells includes culturing MGE-like progenitor cells derived from pluripotent stem cells in the presence of a Notch signaling inhibitor.
  • differentiating pluripotent stem cells includes culturing the population of pluripotent stem cells in the presence of a sonic hedgehog (shh) signaling activator, a TGFbeta signaling inhibitor, and a wnt signaling inhibitor to obtain MGE-like progenitor cells, and further culturing the MGE-like progenitor cells in the presence of a Notch signaling inhibitor, to obtain pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells.
  • a sonic hedgehog (shh) signaling activator e.g., a sonic hedgehog (shh) signaling activator
  • TGFbeta signaling inhibitor e.g., TGFbeta signaling inhibitor
  • wnt signaling inhibitor e.g., wnt signaling inhibitor
  • MGE-like progenitor cells e.g., a Notch signaling inhibitor
  • a Notch signaling inhibitor
  • the CDK signaling inhibitor includes, without limitation, PD0332991, ribociclib, abemaciclib, flavopiridol, or AT7519. In some embodiments, the CDK signaling inhibitor includes PD0332991. In some embodiments, the CDK signaling inhibitor is added to the culture at the start of the third time period (e.g., around D28 of the differentiation time course).
  • the CDK signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the third time period (e.g., D28, D29, D30, D31, D32, D33, D34, D35, D36, D37, D38, D39, D40 or later of the differentiation time course).
  • the cells are cultured in the presence of the CDK signaling inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the third time period.
  • the cells are cultured in the presence of the CDK signaling inhibitor between D28-D42, D28-D35, D29-D35, D29-D42, D30-D33, D30-D35, D35-D42, or D35-D40 of the differentiation time course.
  • the CDK signaling inhibitor can be used to promote cell cycle exit and differentiation.
  • the CDK signaling inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 ⁇ M, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 ⁇ M, 50 nM-100 ⁇ M, 100 nM-100 ⁇ M, or 100 nM-50 ⁇ M). In some embodiments, the CDK signaling inhibitor is provided in the culture medium at a concentration of or of about 10 ⁇ M.
  • the MEK signaling inhibitor includes, without limitation, PD0325901. In some embodiments, the MEK signaling inhibitor includes PD0325901. In some embodiments, the MEK signaling inhibitor is added to the culture at the start of the third time period (e.g., around D28 of the differentiation time course). In some embodiments, the MEK signaling inhibitor is not added to the culture during the second time period, and is added at the start of the third time period (e.g., at D28 of the differentiation time course).
  • the MEK signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the third time period (e.g., D28, D29, D30, D31, D32, D33, D34, D35, D36, D37, D38, D39, D40 or later of the differentiation time course).
  • the cells are cultured in the presence of the MEK signaling inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the third time period.
  • the cells are cultured in the presence of the MEK signaling inhibitor between D28-D42, D28-D35, D29-D35, D29-D42, D30-D33, D30-D35, D35-D42, or D35-D40 of the differentiation time course.
  • the MEK signaling inhibitor can be used to promote cell cycle exit and differentiation.
  • the MEK signaling inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 2, 5, 10, 20, 50, 100, or 200 ⁇ M, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 ⁇ M, 50 nM-100 ⁇ M, 100 nM-100 ⁇ M, or 100 nM-50 ⁇ M). In some embodiments, the MEK signaling inhibitor is provided in the culture medium at a concentration of or of about 2 ⁇ M.
  • differentiating the population of pluripotent stem cells includes further culturing the cells (e.g., differentiating cells) that have been cultured for the second time period (e.g., expanded and committed cells), in the presence of a wnt signaling activator (e.g., a wnt, a GSK3 inhibitor, beta-catenin activator, etc.) during at least a portion of the third time period.
  • a wnt signaling activator e.g., a wnt, a GSK3 inhibitor, beta-catenin activator, etc.
  • Any suitable wnt signaling activator can be used.
  • the wnt signaling activator is, without limitation, BIO(6-bromoindirubin-3'- oxime), LY2090314, SB-216763, CHIR99021, WAY 262611, LP 922056, or DCA.
  • the wnt signaling activator is added to the culture at the start of the third time period (e.g., around D28 of the differentiation time course).
  • the wnt signaling activator is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the third time period (e.g., D28, D29, D30, D31, D32, D33, D34, D35, D36, D37, D38, D39, D40 or later of the differentiation time course).
  • the cells are cultured in the presence of the wnt signaling activator for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the third time period.
  • the cells are cultured in the presence of the wnt signaling activator between D28-D42, D28-D35, D29-D35, D29-D42, D30-D33, D30-D35, D35-D42, or D35-D40 of the differentiation time course.
  • the wnt signaling activator can be used to promote cell cycle exit and differentiation.
  • the wnt signaling activator is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 ⁇ M, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 ⁇ M, 50 nM-100 ⁇ M, 100 nM- 100 ⁇ M, or 100 nM-50 ⁇ M).
  • deriving the MGE-type inhibitory (e.g., GABAergic) neuron cells does not include sorting the differentiating population of pluripotent stem cells, e.g., using FACS or MACS, based on expression of an exogenous marker for MGE-type progenitors.
  • the pluripotent stem cells do not have or express an exogenous marker for MGE-type lineage cells (e.g., a transgenically-expressed marker for MGE-type progenitors or GABAergic cortical interneurons).
  • the MGE-type inhibitory (e.g., GABAergic) neuron cells are derived from pluripotent cells without using sorting techniques, e.g., FACS or MACS, based on expression of an exogenous MGE-type progenitor marker.
  • deriving the MGE-type inhibitory (e.g., GABAergic) neuron cells includes enriching for cells expressing one or more MGE-type neuron-specific cell-surface markers (e.g., one or more pallial, MGE-type interneuron-specific cell-surface markers). Any suitable option can be used to enrich the differentiating population for cells based on expression of one or more MGE-type neuron-specific cell-surface markers (e.g., one or more pallial, MGE- type interneuron-specific cell-surface markers). Suitable options include, without limitation, flow cytometry, FACS, MACS, etc.
  • deriving the MGE-type inhibitory (e.g., GABAergic) neuron cells does not include sorting for cells expressing one or more MGE-type interneuron- specific cell-surface markers.
  • the population of differentiated cells includes a mix of pallial, MGE-type GABAergic interneuron cells (e.g., cells expressing markers for the pallial, MGE-type GABAergic interneuron lineage) and subpallial, MGE-type GABAergic neuron cells (e.g., cells expressing markers for the subpallial, MGE-type GABAergic neuron lineage), without sorting.
  • MGE-type GABAergic interneuron cells e.g., cells expressing markers for the pallial, MGE-type GABAergic interneuron lineage
  • subpallial, MGE-type GABAergic neuron cells e.g., cells expressing markers for the subpallial, MGE-type GABAergic neuron lineage
  • differentiating the pluripotent stem cells according to options described herein generates, without sorting, a population of MGE-type GABAergic neuron cells that is or is about 80%, 85%, or 90%, or a percentage in a range defined by any two of the preceding values (e.g., 80-90%, 85-90%, 80-85%) of the pallial interneuron lineage.
  • differentiating the pluripotent stem cells according to options described herein generates, without sorting, a population of MGE-type GABAergic neuron cells that is or is about 10%, 15%, or 20%, or a percentage in a range defined by any two of the preceding values (e.g., 10-20%, 15-20%, 10-15%) of the subpallial neuron lineage.
  • differentiating pluripotent stem cells to obtain subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cells is carried out using any suitable option.
  • subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cells are obtained by differentiating pluripotent stem cells as described herein, and enriching for LHX6+, ERBB4-, LHX8+ and/or NKX2.1+, GAD1+ cells.
  • subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cells are obtained by differentiating pluripotent stem cells as described herein, but omitting the MEK inhibitor during the differentiation process.
  • subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cells are enriched by sorting for cells, for example, by FACS or MACS.
  • subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cells are enriched by sorting for cells using binding agents to one or more surface markers (e.g., NRP2+) expressed on cells of the subpallial lineage.
  • subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cells are enriched by depleting non-pallial cells using binding agents to one or more surface markers (e.g., ERBB4+) not expressed on cells of the subpallial lineage.
  • the subpallial, MGE-type GABAergic neuron cells include interneurons and/or projection neurons.
  • the method includes cryopreserving the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) after deriving the cells from the pluripotent stem cells.
  • the method includes thawing a cryopreserved cellular composition that includes the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) before administering the cells.
  • MGE-type inhibitory e.g., GABAergic
  • the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells are autologous to the subject.
  • the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells e.g., pallial, MGE-type GABAergic interneuron cells
  • the interneurons, precursors, and/or pluripotent stem cells of the present disclosure are genetically modified.
  • the interneurons, precursors, and/or pluripotent stem cells of the present disclosure include one or more mutations (e.g., nucleic acid substitutions, deletions, insertions, chromosomal rearrangements, etc.) relative to a native genome.
  • the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells e.g., pallial, MGE-type GABAergic interneuron cells
  • the genetic modification alters (e.g., reduces, abolishes, enhances, etc.) an expression and/or function of a gene product (e.g., protein) regulated or encoded by the modified genetic locus.
  • Any suitable genetically-encoded function can be altered through genetic modification of the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells (and/or precursor thereof).
  • the pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells are genetically modified to reduce an immunological response against the administered cellular composition by the subject.
  • MGE-type inhibitory neuron cells e.g., pallial, MGE-type GABAergic interneuron cells
  • Any suitable gene immune- activating genes can be mutated to reduce or abolish activity, or can be knocked out, and/or any suitable genetic modification that activates expression or activity of immune-inhibiting genes can be present in the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells.
  • the pluripotent stem cell-derived, pallial, MGE- type GABAergic interneuron cells are genetically modified to reduce or abolish expression of one or more of: B2M, a HLA class I gene, and/or a HLA class II gene.
  • the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells are genetically modified to knock out one or more of: B2M, a HLA class I gene, and/or a HLA class II gene.
  • SYSTEMS [0189] Also provided is a delivery system for transplanting cells, such as but not limited to pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) as provided herein, into a tissue, such as but not limited to one or more regions of the brain, as provided herein.
  • pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells e.g., pallial, MGE-type GABAergic interneuron cells
  • a tissue such as but not limited to one or more regions of the brain, as provided herein.
  • the system can include a delivery cannula (or catheter, or similar device) that includes: a proximal portion comprising a cellular liquid composition having cells (e.g., pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells), or NRTX-1001) at a concentration of about 1 x 10 5 cells/ ⁇ L or greater; and a distal portion comprising a liquid chase vehicle, wherein the cellular liquid composition is stably held in the proximal portion by the liquid chase vehicle; and a displacement device (e.g., a syringe with optional syringe pump) connected to the distal end of the cannula and configured to cause the liquid chase vehicle to displace the cellular liquid composition to thereby expel the cellular liquid composition from the proximal end of the cannula.
  • a delivery cannula or catheter, or
  • a stylet that traverses the inner lumen of the cannula is used to displace the cellular liquid composition, with or without the liquid chase vehicle, to thereby expel the cellular liquid composition from the proximal end of the cannula.
  • the cellular liquid composition can include cells at any suitable concentration, as described herein, such as at about 1 x 10 5 cells/ ⁇ L or greater (e.g., about 0.5 x 10 6 cells per microliter to about 1.5 x 10 6 cells per microliter, about 0.9 x 10 6 cells per microliter to about 1.2 x 10 6 cells per microliter, or about 1 x 10 6 cells per microliter).
  • the cellular liquid composition includes cells at a concentration of about 1 x 10 5 cells/ ⁇ L or greater, and up to about 2 x 10 6 cells per microliter. In some embodiments, the cellular liquid composition includes cells at a concentration of, of about, or of at least 0.1 x 10 6 , 0.2 x 10 6 , 0.3 x 10 6 , 0.4 x 10 6 , 0.5 x 10 6 , 0.6 x 10 6 , 0.7 x 10 6 , 0.8 x 10 6 , 0.9 x 10 6 , 1 x 10 6 , 1.1 x 10 6 , 1.2 x 10 6 , 1.3 x 10 6 , 1.4 x 10 6 , 1.5 x 10 6 , 1.6 x 10 6 , 1.7 x 10 6 , 1.8 x 10 6 , 1.9 x 10 6 , or 2 x 10 6 cells per microliter, or at a concentration in a range defined by any two of the preceding values (e.g.,
  • the cellular liquid composition includes cells at a concentration of about 0.6 x 10 6 cells per microliter to about 1.2 x 10 6 cells per microliter.
  • the system includes a pump (e.g., syringe pump) connected to the displacement device.
  • a delivery system for transplanting cells can include a delivery cannula containing a cellular liquid composition comprising cells at a concentration of about 1 x 10 5 cells/ ⁇ L or greater; and a displacement device connected to a distal end of the cannula and configured to displace the cellular liquid composition in the cannula to thereby expel the cellular liquid composition from the proximal end of the cannula.
  • the displacement device includes a stylet configured to traverse the inner lumen of the delivery cannula to thereby expel the cellular liquid composition from the proximal end of the cannula.
  • the system includes a monitoring device configured to monitor the delivery site in the subject’s brain during administration of the cellular composition.
  • the monitoring device is configured to detect the position of the proximal end of the cannula at a site of delivery in a subject. Any suitable monitoring device can be used.
  • the monitoring device includes, without limitation, a CT scanner, MRI scanner, PET scanner, or a SPECT scanner.
  • a method of treating seizure activity comprising: identifying a subject in need of treating seizure activity; and administering to the subject a therapeutically effective amount of a cellular composition comprising pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1, and wherein a frequency of seizures is reduced after the administering, thereby treating the seizure activity. 2.
  • a cellular composition comprising pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1, and wherein a frequency of seizures is reduced after the administering, thereby treating the seizure activity.
  • the method of any one of the preceding arrangements wherein at most 40% of the cells of the composition express LHX8. 10. The method of any one of the preceding arrangements, wherein the at least 50% of the cells of the composition further express at least one of MAF and MAFB. 11. The method of any one of the preceding arrangements, wherein the therapeutically effective amount comprises about 5 x 10 4 cells or more. 12. The method of arrangement 11, wherein the therapeutically effective amount comprises between about 5 x 10 4 to about 1 x 10 12 cells. 13. The method of any one of the preceding arrangements, wherein the therapeutically effective amount of the cellular composition is administered at a concentration of about 1 x 10 5 cells/ ⁇ L or greater. 14.
  • the cellular composition comprises sodium chloride at 100-600 mM. 15. The method of any one of the preceding arrangements, wherein the cellular composition has an osmolality of at least 200 mOsm/kg. 16. The method of any one of the preceding arrangements, wherein at most 40% of the cells express an MGE progenitor cell marker or a non-pallial MGE-type neural cell marker. 17. The method of any one of the preceding arrangements, wherein at most 10% of the cells of the composition express KI67. 18. The method of any one of the preceding arrangements, wherein at most 10% of the cells of the composition express OLIG2. 19.
  • the method of any one of the preceding arrangements wherein the subject suffers from focal seizure activity. 26.
  • the method of any one of the preceding arrangements comprising administering the therapeutically effective amount of the cellular composition to the subject’s brain.
  • 27. The method of any one of the preceding arrangements, further comprising performing one or more of computed tomography (CT) scan, magnetic resonance imaging (MRI), MR spectroscopy (MRS), functional MRI (fMRI), electroencephalography (EEG), intracranial EEG, positron emission tomography (PET), and single photon emission computed tomography (SPECT) on the subject.
  • CT computed tomography
  • MRI magnetic resonance imaging
  • MRS MR spectroscopy
  • fMRI functional MRI
  • EEG electroencephalography
  • intracranial EEG intracranial EEG
  • PET positron emission tomography
  • SPECT single photon emission computed tomography
  • the method of any one of the preceding arrangements further comprising identifying a mesial temporal sclerosis in the subject, or one or more lesions in the brain.
  • identifying the mesial temporal sclerosis in the subject or the one or more lesions comprises performing one or more of a CT scan, MRI, MRS, EEG, PET, SPECT, or fMRI.
  • 31. The method of any one of the preceding arrangements, wherein the frequency of seizures is reduced by about 50% or more after the administering.
  • the cellular composition is a thawed cellular composition.
  • 34 The method of arrangement 33, comprising holding the thawed cellular composition for up to about 5 days before administering to the subject.
  • 35 The method of arrangement 33 or 34, comprising holding the thawed cellular composition at an ambient temperature of 4-25°C, or 2-18°C, or at room temperature, before administering to the subject.
  • 36 The method of any one of the preceding arrangements, further comprising thawing a cryopreserved cellular composition comprising the pluripotent stem cell-derived, pallial, MGE-type, inhibitory (e.g., GABAergic) interneuron cells before administering. 37.
  • the administering comprises administering the cellular composition as one or more deposits in the subject’s brain. 38. The method of arrangement 37, wherein the therapeutically effective amount of the cellular composition is delivered in a volume of about 50 ⁇ L or less per deposit. 39. The method of any one of the preceding arrangements, wherein the administering comprises administering the cellular composition to one or more sites in the temporal lobe, optionally wherein the one or more sites in the temporal lobe include the hippocampus, cortex, and/or amygdala, optionally wherein the one or more sites in the temporal lobe include the hippocampus, subiculum, entorhinal cortex, and/or parahippocampal gyrus.
  • the cells are human cells. 41. The method of any one of the preceding arrangements, wherein the subject is a human subject. 42. The method of any one of the preceding arrangements, further comprising administering an immunosuppressant before and/or after administering the therapeutically effective amount of the cellular composition. 43. The method of any one of the preceding arrangements, wherein the seizure activity is due to a traumatic brain injury, stroke, tumor, focal cortical dysplasia, tuberous sclerosis, developmental disorder, or a neurological disorder. 44.
  • the method of any one of the preceding arrangements wherein the subject suffers from epileptic seizure-like discharges in the brain associated with Alzheimer’s disease, focal cortical dysplasia (FCD), or amnesic mild cognitive impairment (aMCI).
  • the method of any one of the preceding arrangements further comprising monitoring a therapeutic effect of administering the cellular composition in the subject. 46.
  • the method of arrangement 45 comprising non-invasively monitoring the therapeutic effect using one or more biomarkers of seizure activity.
  • the one or more biomarkers comprises N-acetylaspartate (NAA), myoinositol, glutamate, GABA, volume, edema, blood flow, oxygen metabolism, and glucose.
  • a method of treating seizure activity comprising: identifying a subject in need of treating seizure activity; and intracranially administering to the subject a cellular composition comprising: about 5 x 10 4 to about 1 x 10 12 pluripotent stem cell-derived, pallial, MGE- type GABAergic interneuron cells at a concentration in a range of about 1 x 10 5 to about 4 x 10 6 cells/ ⁇ L, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1, wherein 90% or more of the cells of the composition are post-mitotic cells; a poloxamer at 0.1-1%, v/v; and sodium chloride at 100-600 mM.
  • compositions for the treatment of seizure activity in a subject comprising pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and at least one of MAF and MAFB, optionally wherein at least 90% of the cells are post-mitotic cells. 51.
  • pluripotent stem cell-derived, pallial, MGE-type inhibitory e.g., GABAergic
  • MGE-type inhibitory e.g., GABAergic
  • a therapeutic composition comprising: a poloxamer; and pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells at a concentration of about 1 x 10 5 cells/ ⁇ L or greater. 54.
  • pluripotent stem cell-derived, pallial, MGE-type inhibitory e.g., GABAergic
  • a method of preparing a therapeutic composition for administering to a subject comprising: providing pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells; and preparing a cellular composition comprising: a poloxamer; and the pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells at a concentration of about 1 x 10 5 cells/ ⁇ L or greater. 55.
  • pluripotent stem cell-derived, pallial, MGE-type inhibitory e.g., GABAergic
  • a delivery system for transplanting cells into a tissue comprising: a delivery cannula comprising: a proximal portion comprising a cellular liquid composition comprising cells at a concentration of about 1 x 10 5 cells/ ⁇ L or greater; and a distal portion comprising a cell-free liquid chase vehicle, wherein the cellular liquid composition is stably held in the proximal portion by the liquid chase vehicle; and a displacement device connected to a distal end of the cannula and configured to cause the liquid chase vehicle to displace the cellular liquid composition to thereby expel the cellular liquid composition from a proximal end of the cannula.
  • a delivery system for transplanting cells into a tissue comprising: a delivery cannula comprising a cellular liquid composition comprising cells at a concentration of about 1 x 10 5 cells/ ⁇ L or greater; and a displacement device connected to a distal end of the cannula and configured to displace the cellular liquid composition in the cannula to thereby expel the cellular liquid composition from a proximal end of the cannula.
  • the delivery system of any one of arrangements 55-58, wherein the cellular liquid composition comprises a contrast agent.
  • the contrast agent comprises an MRI contrast agent.
  • the monitoring device comprises a CT scanner, MRI scanner, PET scanner, or a SPECT scanner.
  • the delivery system of any one of arrangements 55-63, wherein the cells are neuron cells. 65.
  • the delivery system of arrangement 64 wherein the cells comprise pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells.
  • a method of treating seizure activity comprising: identifying a subject in need of treating seizure activity; and administering to the subject a therapeutically effective amount of a cellular liquid composition comprising pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells using the system of any one of arrangements 55-65, wherein the cellular liquid composition comprises the pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells.
  • the method of arrangement 66 comprising detecting the position of the delivery cannula in the subject’s brain during the administering.
  • the method, therapeutic composition, or delivery system of any one of the preceding arrangements wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1, and wherein at least 90% of the cells are post-mitotic cells. 71.
  • the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells are genetically modified to reduce an immunological response against the administered cellular composition by the subject, optionally wherein the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells comprises: a mutation in one or more immune-activating genes that reduces or abolishes expression or activity thereof; and/or a genetic modification that activates expression or activity of one or more immune-inhibiting genes.
  • anti-seizure drugs have been designed to decrease neuronal activity.
  • ASDs that potentiate the inhibitory neurotransmitter GABA are effective acute seizure suppressants.
  • these drugs are typically not first-line medications for chronic epilepsy due to systemic and neurotoxic side effects, tolerance, and addiction.
  • Inhibitory cell therapy represents a strategy that could locally restore normal GABAergic tone to seizure-onset foci and thereby repair underlying pathophysiology.
  • Pallial commonly referred to as “cortical” GABAergic local circuit interneurons are the primary source of inhibition in the neocortex and hippocampus.
  • Pallial interneurons are born in subcortical germinal zones and migrate tangentially to the cortex and hippocampus, where they disperse to their final positions and gradually acquire mature neurochemical and physiological characteristics.
  • Different types of pallial interneurons are generated by distinct germinal domains in the developing subpallium: the MGE and the nearby preoptic area (POA) generate somatostatin (SST)- and parvalbumin (PV)-expressing pallial interneuron classes, while the caudal ganglionic eminence (CGE) generates serotonin receptor 3A (HTR3A)-expressing interneuron classes.
  • MGE-derived interneurons including SST, neuropeptide Y (NPY), and PV-expressing subtypes
  • SST neuropeptide Y
  • PV-expressing subtypes A loss of MGE-derived interneurons, including SST, neuropeptide Y (NPY), and PV-expressing subtypes, has been observed in hippocampal tissue resected from MTLE patients or post-autopsy. Furthermore, mutations in genes required for interneuron generation and function have been identified in various developmental epileptic disorders. Consistent with these findings, SST and PV interneuron subtypes are lost or dysfunctional in animal models of epilepsy. Additionally, seizures can be induced by selective MGE-type pallial interneuron ablation and reduced by selective MGE- type interneuron activation. [0197] Proof-of-concept efficacy of inhibitory interneuron cell therapy has been demonstrated after transplantation of primary embryonic rodent MGE cells into experimental models of epilepsy.
  • hPSCs Human pluripotent stem cells
  • MGE-like progenitors have been published using either embryonic or induced pluripotent stem cells.
  • Subsequent transplantation studies of hPSC-derived GABAergic neurons into experimental epilepsy models reported promising results, including seizure reduction.
  • cortical interneurons these cell preparations were not specifically enriched for cortical or pallial-type MGE-derived interneurons. Rather, each consisted of a mixture of different GABAergic populations, including CGE-derived interneurons and likely non-migratory GABAergic projection neurons, as evidenced by marker expression and graft phenotypes in the above reports. This distinction is important because MGE progenitors produce several cell lineages in addition to pallial GABAergic interneurons, including GABAergic and cholinergic striatal interneurons, GABAergic and cholinergic subpallial projection neurons, oligodendrocytes, and astrocytes.
  • the human pallial MGE-type interneurons were harvested and cryopreserved at a committed post-mitotic, migratory stage of development to ensure dispersion and integration within local circuits, mitigating the risks of proliferation and differentiation into undesired cell fates.
  • Extensive molecular and functional characterization of the cell therapy candidate was made, including single-cell RNA sequencing (scRNA-seq), in vitro migration, and GABA secretion analyses.
  • scRNA-seq single-cell RNA sequencing
  • hESC-derived pallial MGE-type interneurons were analyzed for cellular migration and persistence, graft composition, synaptic connectivity, and dose- dependent reduction of seizure activity.
  • human pallial MGE-type GABAergic interneuron cell therapy can provide treatment of drug-resistant focal epilepsies.
  • Example 2 [0201] This non-limiting example provides materials and methods used in Examples 3-10.
  • A. In vitro hESC line and banks [0202] The pallial MGE-type GABAergic interneurons described in this study were differentiated from research-grade working cell banks derived from a human embryonic stem cell (hESC) line. The cell line is listed in the NIH hESC Registry as an “Approved Line” (eligible for use in NIH-supported research). Donor consent was obtained for use of the cells in research, clinical and commercial development.
  • Donor screening was performed using FDA’s Donor Eligibility Guidelines for HCT/Ps.
  • the cell line was derived, expanded, and banked under cGMP conditions using qualified raw materials to generate a GMP seed cell bank (SCB), and research-grade master cell banks (rMCB) and working cell banks (rWCB).
  • SCB GMP seed cell bank
  • rMCB research-grade master cell banks
  • rWCB working cell banks
  • Karyotypic analysis and pluripotency marker expression were assessed across all hESC cell banks, demonstrating genomic stability and high purity.
  • the pluripotent stem cell banks were tested for sterility and found negative for relevant viruses, mycoplasma, and adventitious agents.
  • hESC stability [0203] The hESC working cell banks (WCB) were tested for genetic stability per ICH Q5D (ICH_Q5D 1998) by evaluating the cell substrate for consistent production of the intended cell fate.
  • MGE-type patterning and differentiation to pallial interneurons using the manufacturing process was initiated from rWCB ESCs after up to five additional passages of ESC expansion to reflect the intended limit of cultivation, and genetic stability was characterized using the complementary orthogonal methods of karyotype analysis by G- banding and single nucleotide polymorphism (SNP) arrays. Since the product being manufactured is post-mitotic and karyotype analysis by G-banding requires mitotic cells, karyotype analysis was performed during the ESC expansion and genome-wide genomic copy number variants (CNVs) and regions of homozygosity analysis (ROH) were assessed during both ESC expansion and end-of-process (EOP) interneuron differentiation using SNP arrays.
  • CNVs genome-wide genomic copy number variants
  • ROH homozygosity analysis
  • hESC expansion A cGMP grade hESC line was adapted to a feeder-free, xeno-free culture system using human recombinant vitronectin (A27940, Life Technologies) coated dishes, Essential 8 medium kit (A2656101, Life Technologies) and dissociation reagent ReLeSR (100-0484, STEMCELL Technologies). Media was changed daily, and cells were passaged every 5 days, for a total of 5 passages, before being cryopreserved to sequentially generate a GMP SCB, and research-grade rMCBs and rWCBs.
  • MGE pallial-type interneuron differentiation For each differentiation experiment, one vial of rWCB was thawed. The thawed hESCs were seeded into adherent culture and expanded for 5 days post-thaw using conditions described above.
  • the expanded hESCs were dissociated into a single cell suspension using StemPro Accutase (A1110501, Life Technologies) and resuspended in differentiation media consisting of Neurobasal-A (50%; 10888, Life Technologies) and DMEM/F12 (50%; 21331, Life Technologies), supplemented with GlutaMAX (1X; 35050-061, Life Technologies), B-27 without Vitamin A (1X; 12587-010 Life Technologies), N2 supplement-B (1X; 07156, Stem Cell Technologies), Penicillin- Streptomycin (1X; 15140-122, Life Technologies), L-Ascorbic Acid (200 ⁇ M; A5960, Sigma), ⁇ -Mercaptoethanol (55M; 21985-023 Life Technologies), and MEM non-essential amino acids (1/2X; 11140-050, Life Technologies).
  • StemPro Accutase A1110501, Life Technologies
  • DMEM/F12 50%; 21331, Life Technologies
  • GlutaMAX 1X; 35050-061, Life Technologies
  • ROCK inhibitor Y27623 10 ⁇ M; 1254 Tocris
  • TGF ⁇ and BMP pathway inhibition induced neuroectoderm SB431542 10 ⁇ M; 1614 Tocris / LDN193189250nM; 6053 Tocris
  • WNT pathway inhibition conferred forebrain identity (XAV939 10 ⁇ M; 3748 Tocris) and SHH pathway activation induced ventral forebrain MGE-like progenitors (SAG 100nM; 4366 Tocris).
  • a MEK pathway inhibitor was applied to further improve the efficiency, kinetics, and specificity of pallial-type GABAergic interneuron lineage (PD0325901 2 ⁇ M; 4192 Tocris).
  • inhibitors of the MEK PD0325901 2 ⁇ M; 4192 Tocris
  • CDK PD0332991 2 ⁇ M; S1116 Selleck Chemicals
  • NOTCH DAPT 10 ⁇ M; 2634 Tocris
  • Unsorted (pre-sort) and sorted (post-positive selection) cell populations were cryopreserved using the CryoMed controlled-rate freezer (Fisher Scientific), before further storage in vapor-phase liquid nitrogen.
  • Immunocytochemistry [0211] Thawed cells were counted using the NC-200 cell counter (Chemometec) and seeded into 384-well plates coated with Poly-L-Ornithine/Fibronectin/Laminin (PO/Fib/Lam) at ⁇ 4.0E5-4.3E5 cells/cm 2 . Cells were fixed with 4% Paraformaldehyde (PFA) for 10 minutes 3-16 hours after plating and processed for staining within two weeks.
  • PFA Paraformaldehyde
  • a blocking buffer (10% Goat Serum, 0.1% Triton X-100 in DPBS (Dulbecco’s phosphate-buffered saline)
  • DPBS Dulbecco’s phosphate-buffered saline
  • Primary and secondary antibody dilutions were prepared in blocking buffer and kept on ice. Primary antibody incubation was done at 4°C overnight, followed by two 30-minute washes with PBS-T (DPBS, 0.1% Triton X-100). Secondary antibodies (Alexa Fluor conjugated, Life Technologies) incubation was done at ambient temperature in the dark for 2 hours, followed by two 30-minute washes with PBS-T. The second wash was replaced with DPBS for imaging and storage.
  • nuclei were identified as primary objects to define regions of interest on subsequent channels, and determine percent of positive cells expressing a given marker, based on morphological and intensity thresholding.
  • Assessment of residual pluripotent cells by flow cytometry [0214] Cells were stained on day 28 and at the end of process (post-thaw) with PE/Cy7 anti-human-TRA-1-60 (Biolegend) for surface TRA-1-60, Fixable Far Red dye (ThermoFisher Scientific) for viability and AF488 anti-human-OCT4 (BD Bioscience) for intracellular OCT4.
  • the cells were analyzed using an Attune-NxT Acoustic Focusing Flow Cytometer and data were analyzed using FlowJo (BD Biosciences) software.
  • FlowJo BD Biosciences
  • an extensive qualification was performed to determine the assay repeatability, accuracy, linearity and limits of detection (LOD) per ICH Q2 guidelines.
  • Samples were stained in triplicate (1E7 cells per sample) for better population statistics. From this study the method was determined to be accurate in detecting pluripotent cells at a LOD of 0.002%. When the method was employed to analyze samples at the end of the process, the percentage of pluripotent cells detected was always below the LOD.
  • Cells were seeded onto a polyornithine/fibronectin/laminin coated 96-well plate at a density of 0.65E6 cells/cm 2 in culture media. Each cell lot was seeded in six wells, and cells were cultured at 37°C, 5% CO2 for 8 days, with media changes every 2-3 days. On day 8, spent medium was replaced with fresh pre-warmed medium either alone or supplemented with 90 mM potassium chloride (in triplicate wells per condition). After a 30-minute incubation at 37°C, 5% CO2, cell-free supernatants were collected and stored at -80°C.
  • hESCs were seeded at a density of 25E3 cells/cm 2 in E8 media containing ROCK inhibitor seventy-two hours prior to sample collection. One day post-seeding, the media was changed to the same neuronal culture media as hESC-derived interneurons, and the cells were fed daily until sample collection.
  • SMNs were thawed and seeded into a polyornithine/fibronectin/laminin coated 96-well plate at a density of 0.65E6 cells/cm 2 and cultured for 8 days as described by the manufacturer. The sample collection was performed the same way for ESCs and SMNs as for the hESC-derived interneurons on day 8.
  • hESC-derived pallial MGE-type interneurons compared to human fetal MGE-derived interneurons and other in vitro-derived GABAergic cell preparations
  • a migration assay was developed, in which cells were aggregated and embedded into a MatrigelTM (CB-40230, Fisher Scientific) drop covered with culture medium, and then incubated for three days to allow for the visualization and quantification of cells migrating away from the main cell aggregate.
  • Primary human MGE was dissected from mid-gestational age tissue (GW18-20) followed by dissociation and sorting for ERBB4. All hPSC-derived interneurons were thawed prior to aggregation.
  • hPSC-derived GABAergic cells were from Cellular Dynamics International (vendor “X”: iCell GABA Neurons, cat #C1008) and BrainXell (vendor “Y”: GABAergic Neurons, cat #BX-0400). Cells from different sources were prepared by one operator, assigned a random ID and handed to a different operator de-identified for assays and data analyses. [0219] To perform the assay, 5E3 cells in 100 ⁇ l of culture medium were spun down in 96-well V bottom plates (S-bio, MS-9096VZ) and allowed to aggregate at 37°C, 5% CO2 over a period of three days.
  • the aggregates were then embedded into a Matrigel TM drop in the center of a 96-well flat bottom assay plate with the aid of a dissecting microscope inside the biosafety cabinet (BSC) (one aggregate per well, twelve aggregates per sample). After a 15-minute incubation at ambient temperature, 200 ⁇ l of culture medium was added to the wells, followed by incubation at 37°C, 5% CO2 for three days. [0220] On day 3 of migration, samples were fixed for 30 minutes with a 2% PFA and 1X Hoechst solution at ambient temperature, protected from light. The fixation solution was washed away three times using DBPS.
  • BSC biosafety cabinet
  • Migration images were acquired using the CX5 instrument with a 4X objective, projecting the maximum intensity across 375 ⁇ m (15 z-plans, 25 ⁇ m steps).
  • the number of Hoechst positive cells that migrated away from the aggregate was quantified automatically using “spot detector” bio application. Percentage of migrating cells was determined based on the number of Hoechst positive spots detected divided by 5E3 (input cells that were aggregated).
  • scRNA-seq analysis was performed using the 10X Genomics platform on the hESCs prior to the start of differentiation, hESC-derived MGE-type VZ-like progenitors on day 14 of differentiation, and six pairs of unsorted/sorted cell lots at the end of the differentiation process. All samples were thawed the day of capture and transported on ice to SeqMatic (Fremont, CA) for downstream processing and data generation.
  • Individual cells were captured and barcoded using the chromium controller, cDNA libraries were prepared using next GEM 3’ V3.1 kits (10x Genomics), cDNA libraries were quantified using the Agilent Tapestation 4200 and pooled for sequencing.
  • Cell Ranger v3.1.0 (10x Genomics) was used to demultiplex FASTQ files for each sample, align reads to the human GRCh38 genome downloaded from 10x Genomics, and quantify the expression levels for each gene in each cell from each sample.
  • R version 4.0.3 and Seurat v3.2.2 were used to quality control, normalize, cluster, and visualize the cells from all samples.
  • Cells were filtered for quality by having at least 1000 expressed genes, at least 1000 unique reads, no more than 20% reads of mitochondrial genes and no more than 40% reads of ribosomal genes. Cells were normalized by the ‘LogNormalize’ method. The top 3000 genes were identified by ‘FindVariableFeatures’ with ‘vst’ selection method for downstream integration analysis. Seurat CCA (Canonical Correlation Analysis) integration workflow was applied to remove the batch effects between different cell lots. hESCs and Day 14 progenitors were merged with the integrated differentiated lots for clustering. PCA (Principal component analysis) was applied, 30 PCs (principal components) were selected, and cells were clustered with Seurat standard workflow.
  • PCA Principal component analysis
  • meloxicam (Metacam® 10 mg/kg in 2ml/kg i.p.) as a non-steroidal anti-inflammatory drug, antibiotic enrofloxacin (Baytril® 10 mg/kg in 4.4 ml/kg s.c.), and local anesthesia on the scalp with bupivacaine (2.5 mg/kg in 5 ml/kg s.c.).
  • animals received 1 ml warmed Ringer’s solution s.c. to rehydrate, and their cages were placed on a heating pad until full recovery from anesthesia.
  • mice After acclimation of 2 weeks, animals received 0.21 ⁇ g kainic acid (KA; Tocris) dissolved in 50 nL NaCl into the right dorsal hippocampus to induce epilepsy (coordinates in relation to Bregma: AP -2.0; ML +1.6; DV -1.65), using a pulled glass needle with 70-90 ⁇ m diameter at the tip and a connected microinjection system (Narishige). At this first surgery, the body weight of the animals was 23-24 g on average. After injection of KA, mice were kept under isoflurane anesthesia for a total of 1 hour to avoid the more severe seizures associated with recovery from inhaled anesthesia.
  • KA kainic acid
  • mice After recovery from anesthesia, animals were closely monitored for occurrence of generalized seizures. All mice began seizing within 90 min post-anesthesia and were then returned to the animal housing room in single-housed cages. Status epilepticus (SE) was not interrupted in this model. Mice were injected with 1 mL lactated Ringer’s solution to ensure rehydration during/after SE. Additionally, food pellets and water as a gel were provided at the bottom of the cage. If necessary, mice were placed on heating pads and manually provided with Ensure® liquid diet supplement on the day after SE. If failure to thrive was observed, the mouse was euthanized. Mortality during and within the first days after SE was ⁇ 10%.
  • Electrode implantation and EEG recording [0229] For recording an electroencephalogram (EEG), transmitters from Data Science International (DSI) were implanted and connected in-house to a custom-made bipolar electrode (PlasticsOne). The DSI transmitter was implanted subcutaneously over the left flank of the mouse and the electrode was lowered into the right dorsal CA1 of the hippocampus into the same site as the previous KA injection (coordinates in relation to Bregma: AP -2.0; ML +1.6; DV -1.65).
  • DSI Data Science International
  • the electrode was secured in the skull by implanting three holding screws (2 rostral, 1 caudal) and Loctite glue. Implantation happened in the same surgery as cell/vehicle transplantation or within a few weeks of transplantation surgery.
  • EEG and video recordings (Ponemah; DSI) were acquired in multi-day 24-hour sessions for each animal enrolled in the study; the data were saved to a server approximately daily and archived at least monthly on backup storage hard drives.
  • EEG was recorded 24/7 for 1-3 weeks at various time points post-SE (Fig. 4A) using Ponemah software. Recording time points for most studies were between 1-2 MPT, 5, and 7 MPT.
  • Figs. 14D, 14E Brain slice electrophysiology
  • cells were seeded onto PO/Fib/Lam coated multiwell plates in culture media. Following overnight incubation at 37°C, 5% CO2, culture medium was replaced with fresh medium containing lentivirus supernatants (Lenti-UbC-GFP or Lenti-Syn-ChR2-YFP) based on the optimal titration that was determined empirically in a separate experiment to achieve 95% GFP+ or YFP+ expression. After a three-day incubation, culture medium was removed followed by three washes with PBS to remove any residual viral particles.
  • lentivirus supernatants Li-UbC-GFP or Lenti-Syn-ChR2-YFP
  • a total dose of 200E3 cells/hippocampus was delivered into the mouse hippocampus at 4 different sites (50E3 cells/injection) with respect to bregma (AP: -1.85; ML: +1.8; DV: - 1.7 mm; AP: -2.5; ML: +2.65; DV: -1.9 mm; AP: -3.15; ML: +2.8; DV: -2.4 mm and AP: - 3.15; ML: +3.25; DV: -3.45 mm).
  • mice up to one year of age were deeply anesthetized with intraperitoneal injection of freshly prepared Avertin (250 mg/Kg) and perfused with ice-cold sucrose-based solution (210 mM Sucrose, 2.5 mM KCl, 10 mM MgSO4, 2 mM CaCl2, 1.25 mM NaH2PO4, 24 mM NaHCO3, 11 mM glucose).
  • the brain was removed and sectioned into 300 ⁇ m thick slices, which were transferred to 34°C ACSF (126 mM NaCl, 3 mM KCl, 2 mM MgCl2, 2 mM CaCl2, 1.2 mM NaH2PO4, 26 mM NaHCO3, 10 mM glucose) for 30 minutes at room temperature for no more than 6 hours for later use.
  • 34°C ACSF 126 mM NaCl, 3 mM KCl, 2 mM MgCl2, 2 mM CaCl2, 1.2 mM NaH2PO4, 26 mM NaHCO3, 10 mM glucose
  • mice were deeply anesthetized and transcardially perfused with ice-cold “NMDG-HEPES aCSF” (92 mM NMDG, 92 mM HCl, 2.5 mM KCl, 1.2 mM NaH2PO4, 30 mM NaHCO3, 20 mM HEPES, 25 mM glucose, 5 mM sodium ascorbate, 2 mM thiourea, 3 mM sodium pyruvate, 10 mM MgSO 4 , 0.5 mM CaCl2).
  • the brain was dissected and sectioned into 300 ⁇ m coronal slices. Slices were transferred to 34°C “NMDG-HEPES aCSF” for 40 minutes to recover.
  • Na+ spike-in solution (2 M NaCl in NMDG-HEPES aCSF) was added at the following time points: 15 min: 0.25 mL; 20 min: 0.25 mL; 25 min: 0.5 mL; 30 min: 1 mL; 35 min: 2 mL.
  • HEPES holding aCSF 92 mM NaCl, 2.5 mM KCl, 1.2 mM NaH2PO4, 30 mM NaHCO3, 20 mM HEPES, 25 mM glucose, 5 mM sodium ascorbate, 2 mM thiourea, 3 mM sodium pyruvate, 2 mM MgSO 4 , 2 mM CaCl 2
  • “recording aCSF” 124 mM NaCl, 2.5 mM KCl, 1.2 mM NaH2PO4, 24 mM NaHCO3, 5 mM HEPES, 12.5 mM glucose, 2 mM MgSO4, 2 mM CaCl2).
  • Borosilicate glass pipettes (4-8 Mohm) were backfilled with a solution containing: 140 mM K-gluconate, 2 mM MgCl2, 10 mM HEPES, 0.2 mM EGTA, 4 mM MgATP, 0.3 mM NaGTP, 10 mM Phosphocreatine d-tris, and 0.25% (g/100mL) biocytin.
  • Modified Irwin’s Test General health and wellness of the animals was also assessed using a modified Irwin screen adapted from a protocol used to test safety and tolerability of anti-seizure drugs in naive and epileptic mice. An animal’s sensitivity to touch, noise, tail elevation, and spatial locomotion (mobility) were evaluated, as well as their body position and fur condition. A value of 2 was set as the usual expected reaction for a healthy mouse in the test. Animals were tested in an empty mouse cage in their housing room. One experimenter administered the test while two other experimenters scored the animal or its reaction. Animals were assessed at least twice during the study. If an animal had a generalized seizure during the test, it was excluded.
  • Open Field Test The Open Field test was used to determine exploration, general locomotor activity and anxiety, and animals were tested at approximately 6 MPT. A four-arena maze (each 40cm x 40cm) was used to analyze multiple animals at once. Animals were acclimated to the test room for at least one hour prior to the test. An animal was placed in the center of the open field and allowed to explore for five minutes and then returned to its home cage.
  • Barnes Maze Test The Barnes Maze is a dry-land maze used to assess visual-spatial learning and memory in rats and mice, which is partially impaired in the focal kainate mouse model.
  • the maze is an elevated circular platform with a diameter of 92 cm. Twenty 5 cm holes line the edge of the maze and a hidden chamber is placed underneath one hole. Visual clues were placed around the room and lights acted as a mildly aversive stimulus. Acquisition and probe trials were video recorded using Media Recorder and analyzed using Ethovision XT software.
  • animals On the first day of testing, animals were familiarized with the maze and hidden chamber. The animal was first placed in a red plastic, open-ended cylinder in the center of the maze and after 10 seconds the cylinder was removed.
  • the animal could explore the maze for 2 minutes and after this time the animal was gently guided to the hidden chamber. Once in the chamber, the animal remained there for 1 minute before being returned to the home cage. This step was repeated one more time if animals were resistant to entering the hole. Acquisition trials were run on Days 1-3, and up to three trials were conducted each day. Animals were placed in the room 1 hour before the first trial for acclimation. Each animal had up to 3 minutes to find the hidden chamber and if it did not, the animal was gently guided to the hidden chamber after the time elapsed. The location of the hidden chamber remained the same for all animals during the acquisition trials. The maze and hidden chamber were cleaned between each animal using Nolvasan® solution to avoid odor cues. Animal order was randomized using Random.org.
  • Experimenters were masked to the animal’s treatment. Animals that experienced a generalized seizure during a trial were returned to home cage and retested after 30 minutes if possible. On Day 5 a probe trial was run. During this trial, the escape chamber was removed and each animal had up to 3 minutes to explore the maze. After 3 minutes, the animal was returned to its home cage. To assess long-term retention, an identical second probe trial was run approximately 10 days after the first probe trial. An animal’s trial was excluded from analysis if the animal had a seizure during the trial, the animal was continuously circling, or if the animal fell off the maze more than twice during the trial. Animals were also excluded during probe trials if they didn’t move more than 70 cm.
  • Y-Maze The Y-Maze alternation test is used to determine exploration and spatial memory and has been used in the literature for assessing effects of GABAergic transplants in epileptic mice.
  • the Y-Maze is a three-arm maze and each arm contains a visual cue. Animals were placed in the room one hour before the start of the test for acclimation. To begin the test, the animal is placed in the previously chosen “start” arm facing the center of the maze.
  • the animal can explore for five minutes and then it is returned to its home cage. Animals that experienced a generalized seizure during the test were returned to home cage and re-tested after 30 minutes. Video was recorded using Media Recorder and analyzed using Ethovision XT software. The maze was cleaned between each animal using Nolvasan® solution to avoid odor cues. Animals were tested once, usually at the end of the study. Animals would be excluded from analysis if they didn’t enter each arm at least twice. Outcomes that were evaluated included the number of arms entered, percent alteration, and direction of alteration. Depending on the outcome evaluated, a one-way ANOVA or t-test was run. If the data were nonparametric, Kruskal-Wallis or Mann-Whitney was run.
  • EEG analysis EEG was analyzed by researchers masked to treatment and group allocation either in-house or by the CRO SynapCell (St. Ismier, France). EEG that was not readable due to bad quality of the recording was not sent out for analysis and the animal was excluded from the EEG results. In-house EEG was analyzed using Neuroscore (DSI).
  • Electrographic seizures are defined as synchronous activity with changes in spike frequency with a duration of at least 5 seconds at double the amplitude as baseline EEG.
  • the inter-event interval was set at 1 second.
  • Epileptic mice displayed around 11-15 electrographic seizures/30min early after SE in the MTLE model (Fig. 5F).
  • the same experimenter read the EEG of the same animals at different time points post-transplant to limit variation. A 30-min interval of EEG was analyzed for electrographic seizures each day for 7 consecutive days per time point. All EEGs were analyzed from the same time of day if possible (16:00).
  • EEG traces can become increasingly hard to analyze with time after implantation of the electrodes, the following criteria were applied: (1) if no clean trace for a duration of 30 min was found, the next clean 30 min interval within the next 3 hours was used; (2) if no 30 min clean EEG stretch was found between 16:00-19:00, the EEG was read between 15:00-16:00; (3) if there was no clean EEG interval of 30 min, at least 10 min (continuous) as close to the original time point (16:00) was analyzed; (4) if an event crossed the predicted start/end of the 30-min reading interval, it would still be counted. Animals that did not show any seizure activity at baseline were excluded from the study.
  • RNA fluorescence in situ hybridization was performed on fixed, frozen mouse brain sections using RNAscope Multiplex Fluorescent Reagent Kit v2 Assay (Advanced Cell Diagnostics cat# 323100) according to the manufacturer’s instructions. Briefly, 40 ⁇ m sections were post-fixed with 4% PFA and dehydrated with 50%, 70% and 100% ethanol. Sections were pretreated with hydrogen peroxide and target retrieval was performed. Following a 30-minute protease treatment, they were hybridized to probes targeting human GAD1 (Advanced Cell Diagnostics cat# 404031-C3) and human GAPDH, cross-validated not to recognize the mouse GAPDH gene (Advanced Cell Diagnostics cat# 442201-C2).
  • Brain tissue through the hippocampus was sectioned at 40 ⁇ M on a slide microtome or cryostat in 12 series of sections and processed for immunohistochemistry and chromogenic tissue stains. All brain sections examined were assessed for the presence of ectopic tissue and development of micropathology. Analysis involved determining if the electrode and cell transplantations had been appropriately targeted within the hippocampus, and persistence, distribution and fate of transplanted human cells: One series of sections was stained with Nissl or H&E to assess hippocampal damage and to identify any potential ectopic tissue or teratomas.
  • Granule cell dispersion has been quantified by measurements of the GC layer width and area at -1.8 mm from Bregma, which is close to the site of kainate injection. The average GC layer width (three places, illustrated by white lines in Fig. 8B), and GC layer area (illustrated by the white boundary in Fig. 8B) were quantified using Zen Blue.
  • EEG EEG traces that displayed increased interictal activity and/or generalized seizures and in which it was thus hard to identify electrographic seizures
  • the EEG was analyzed for generalized seizures, and in rare cases in which animals had a high generalized seizure frequency (>3 seizures/day), they were excluded from analysis of electrographic seizures. If an animal did not survive to the endpoint of the study, the EEG data were collected and analyzed up to the point of animal’s death and all data were maintained in the study files.
  • Statistical analysis [0247] For sample size calculations G*Power was used after initial experiments. Analysis was performed using GraphPad Prism 9 (GraphPad). Data were first tested for normal distribution.
  • mice were masked to the treatment for the entire duration of the study and subsequent data analysis. During SE induction surgeries, 2-3 mice from each group cage were chosen randomly to distribute animals across all cages for a surgical day. All mice received the same treatment and were assigned a unique identifier number after surgery. For transplantation surgeries, mice were randomly selected from the holding rack (8 single- housed cages per row, per transplantation day at least 2 cages per row were selected).
  • Treatment group allocation was only noted on surgery sheets and on an electronic database. Access to physical sheets and the database was limited to one person not involved in the study until the study was fully completed and all data were analyzed.
  • the EEG files did not reveal the animal number.
  • EEG was read on a per-channel basis by researchers who were masked to the treatment and animal identifier. The code for channel/animal number was kept at separate sites from the site of experimentation. The experimenters also had no information on the scope of the study, the treatment specifics or time points that they were analyzing. In- house data review was also performed in a masked manner and traces did not contain information to allow identification of the animal number or treatment group.
  • Example 3 This non-limiting example shows differentiation of hESCs into highly enriched pallial MGE-type GABAergic interneurons.
  • MGE precursors defined by the expression of NKX2-1 within the SOX1+, FOXG1+, DLX1/2+ ventral telencephalon (Figs. 9A-9F), give rise to multiple neuronal classes.
  • the LHX6 transcription factor is induced by NKX2-1 in all MGE-derived GABAergic telencephalic lineages (Fig. 2A).
  • LHX6 expression is largely maintained into adulthood in GABAergic lineages, including nearly all SST- and PV- expressing interneurons within the adult cortex and hippocampus. Pallial interneurons express tyrosine kinase receptor ERBB4, which is required for tangential migration.
  • NKX2-1 and LHX8 pallial MGE-derived interneurons are distinguished from the other GABAergic lineages by expression of MAF and MAFB and downregulation of NKX2-1 and LHX8 (Fig. 2A).
  • subpallial MGE-derived GABAergic and cholinergic neurons maintain NKX2-1 and/or LHX8 expression. While several studies reported induction of NKX2-1 from hPSCs along with a GABAergic neuron phenotype, they did not demonstrate downregulation of NKX2-1 and LHX8, or co-expression of LHX6 with MAF, MAFB, and ERBB4, specific to the pallial MGE lineage. [0251] FIGs.
  • FIGS. 9A-9H In vitro characterization of hESC-derived VZ-like MGE progenitors on Day 14.
  • FIGs. 9A-9F Comparison of marker expression in hESC- derived MGE-like progenitors by immunocytochemistry (ICC) with in situ hybridization data from the Allen Developing Mouse Brain Atlas, E13.5 (2008).
  • FIGs. 9A-9C Combination of FOXG1, NKX2-1 and OTX2 expression in the vast majority of hESC-derived progenitors is consistent with rostroventral MGE patterning corresponding to the ventricular zone (VZ)-like developmental stage.
  • FIGs. 9D LHX6 expression defines the MGE subventricular zone (SVZ) and mantle zone (MZ), and is not yet expressed at this stage of differentiation.
  • FIGs. 9E, 9F Markers corresponding to off-target regions including dorsal telencephalon (PAX6) and hypothalamus (NKX2-2) are not expressed in the hESC-derived MGE-like progenitors.
  • FIGs. 2A-2G Post thaw in vitro characterization of end-of-process cell lots.
  • FIG. 2A Simplified schematic of neuronal subtypes derived from the MGE progenitor domain (FOXG1+ DLX1/2+ NKX2-1+), including pallial GABAergic interneurons (IN) that migrate to the cortex and hippocampus, as well as multiple lineages that remain in the subpallium.
  • the latter consist of striatal GABAergic and cholinergic Ins, cholinergic projection neurons (PN), and GABAergic PNs of the globus pallidus.
  • the listed genes play critical roles in the specification of the indicated neuronal lineages. (FIGs.
  • FIG. 2B, 2C Representative ICC images showing expression of the MGE marker LHX6 as well as pallial MGE markers MAFB, MAF and ERBB4 in the unsorted and sorted Lot 1.
  • FIGs. 2E, 2F Neurotransmitter release assay from hESC-derived MGE interneuron lots (unsorted and sorted lots are plotted together, as no significant differences were observed), undifferentiated hESCs and spinal motor neuron cultures.
  • FIGs. 10A-10J Efficient and reproducible hESC differentiation into MGE-type pallial interneurons.
  • FIG. 10A Schematic of MGE pallial-type interneuron differentiation protocol and key markers used to characterize each stage.
  • FIGs. 10B-10G Representative images (FIGs. 10B, 10D, 10F) and automated quantification (FIGs.
  • FIGs. 10H-10J Effect of a MEK pathway inhibitor during differentiation on subpallial marker LHX8 and pallial interneuron marker ERBB4.
  • Cells can be transplanted at a post-mitotic stage, rather than at a progenitor stage, to reduce or prevent potential proliferation and/or differentiation into off-target cell types. Previous transplantations of hPSC–derived GABAergic cells from the progenitor stage gave rise to mixed graft composition with residual cycling cells.
  • FIGs. 11A-11I No residual proliferative progenitors or pluripotent stem cells identified in the end-of-process (week 6) samples.
  • FIGs. 11A-11C Comparison of % KI67+ (FIG. 11A) and % 5-ethynyl-2’-deoxyuridine (EdU+) (FIGs. 11B, 11C) cells detected in unsorted cultures at the end-of-process without treatment (NT), versus NOTCH inhibition alone (NOTCHi), versus combined NOTCH and CDK4/6 inhibition (NOTCHi + CDKi) prior to cryopreservation.
  • FIG. 11F Data are expressed as a mean ⁇ SEM.
  • FIGs. 11B, 11C Two pulses of EdU were added to the culture during the last week of differentiation.
  • FIG. 11G-11I Representative evaluation of pluripotency markers (TRA-1- 60 and OCT4) by flow cytometry for in-process (week 2, FIG. 11G) and end-of-process (week 6, FIG. 11H) samples.
  • FIG. 11I Experimentally-determined assay limits of detection (LOD) for the two time points.
  • LOD Experimentally-determined assay limits of detection
  • an assay to measure pluripotent stem cell markers POU5F1 (OCT4) and TRA-1-60 was developed using flow cytometry on in-process (week 2) and end-of-process (EOP, week 6) samples (Figs. 11G-11I). Analyzing post-thaw samples in triplicate (10 x 10 6 cells per sample), no pluripotent cells were detected above the limits of detection (LOD 0.002%, FIG. 11I).
  • hPSC-derived GABAergic neurons While all the hPSC-derived GABAergic neurons expressed VGAT, only the pallial MGE- type interneurons expressed high levels of LHX6, MAFB, MAF, and ERBB4, and lacked expression of progenitor (OTX2), glial (GLAST), CGE (COUPTF2, SP8), and other off- target markers (ISL1, NKX2-2) (Figs. 12B, 12D, 12E). Furthermore, hESC-derived pallial MGE-type interneurons demonstrated migratory properties remarkably similar to endogenous human MGE interneurons in terms of morphology and extent of in vitro migration; this phenotype was not observed in the other types of GABAergic neurons (Figs. 12A-12C).
  • FIGs. 12A-12E In vitro migration phenotypes of hESC-derived pallial MGE-like pallial interneurons compared to human endogenous MGE interneurons and commercially available hPSC-derived GABAergic cells. (FIG.
  • FIG. 12A In vitro migration assay was performed with human fetal MGE cells sorted for pallial interneuron surface marker (GW 18-20), hESC-derived pallial MGE-type interneurons (IN; unsorted and sorted) and two commercial sources of hPSC-derived GABAergic neurons. Cell identity was masked from the operator during assay set up and analyses. Phase contrast images were taken at the start of migration assay (Day 0, left most panel) and after three days. Higher magnification images show migrating cell morphology.
  • FIG. 12B Aggregates were fixed after 3 days of migration and processed for ICC using antibodies against LHX6, MAFB and ERBB4.
  • FIG. 12C Quantification of percent migrating cells after 3 days.
  • Each dot is from a biological replicate and represents an average of 8-12 technical replicates. Data are expressed as a mean ⁇ SEM.
  • FIGs. 12D, 12E Marker expression by ICC comparing hESC-derived pallial GABAergic MGE-type interneurons prepared by a differentiation process discloses herein (left column) with two commercial sources of hPSC-derived GABAergic neurons. Key: “-” no detectable expression, “+” expressed in less than 10% of cells, “++” expressed in 10-50% of cells, “+++” expressed in 50-90% of cells, “++++” expressed in >90% of cells.
  • cortical inhibitory interneurons suitable for use in methods of the present disclosure are differentiated in vitro from human embryonic stem cells (hESCs).
  • the differentiated cells are enriched for cells expressing on-target markers for post-mitotic GABAergic interneurons of an MGE-type cortical lineage compared to undifferentiated hESCs or MGE-type progenitor cells.
  • the differentiated cells are enriched for cells expressing at least LHX6 and ERBB4 compared to undifferentiated hESCs or MGE-type progenitor cells.
  • at least 90% of the differentiated cells express LHX6.
  • the differentiated cells express ERBB4. In some embodiments, about 80% (or at least 75%) of the differentiated cells express MAF. In some embodiments, about 75% (or at least 50%) of the differentiated cells express MAFB. In some embodiments, at most 40% (or at most 30%) of the differentiated cells express LHX8. In some embodiments, about 50% (or 20-80%) of the differentiated cells express NKX2-1. In some embodiments, the differentiated cells are depleted of or substantially free of cells expressing off-target markers (including markers for mitotic precursor cells.
  • the differentiated cells are depleted of or substantially free of cells expressing OTX2, SP8, ISL1, NKX2.2, OLIG2, Ki67, and LHX8.
  • the differentiated cells are depleted of or substantially free of cells expressing markers for cell cycle (Ki67), pluripotency (POU5F1), glial cells (SLC1A3, OLIG2, GFAP), cholinergic neurons (SLC18A3), glutamatergic neurons (SLC17A7), dopaminergic neurons (TH) and/or serotonergic neurons (TPH1).
  • the differentiated cells are depleted of cells expressing markers for MGE-type progenitors (NKX2-1, VIM).
  • Example 4 shows that single cell RNAseq profiling confirms pallial MGE-type GABAergic interneuron identity.
  • scRNA-seq was performed for three cell states: Day 0 hESCs prior to the start of differentiation, Day 14 MGE-type VZ-like neural progenitor cells (NPCs), and end-of- process (EOP, week 6) interneurons (several paired unsorted/sorted lots, including lots 1 and 2 used in the efficacy studies described below). All samples were previously cryopreserved and processed for sequencing post-thaw.
  • FIGs. 3A-3E Single cell RNA sequencing characterization of cell composition during in vitro differentiation and comparison with human developing GE dataset. scRNA-seq was performed on post-thaw cell preparations, including hESCs prior to the start of differentiation (Day 0), in-process MGE-type VZ-like progenitors (Day 14), and several paired (unsorted/sorted) end-of-process (week 6) interneuron lots, including lots 1 and 2. (FIGs.
  • FIG. 3A, 3B UMAP (Uniform Manifold Approximation and Projection) visualization of cell clusters in all the combined samples (FIG. 3A), and in each of the separate samples listed (FIG. 3B).
  • FIG. 3C Quantification of sample composition by cluster.
  • FIG. 3D Feature plot visualizations of gene expression across clusters 0-5. All cells are displayed in light gray, cells with detectable expression are displayed in purple, with darker shade corresponding to higher expression level.
  • Cluster 1 had higher expression of NKX2-1 and the radial glia stem cell and neural progenitor markers VIM, NES, PTPRZ1 and FABP7, whereas Cluster 2 had higher expression of neuronal and GABAergic markers DCX, MAP2, GAD1/2 and DLX1/2/5 (Figs. 3D, 3E).
  • Cluster 5 had higher expression of genes required for pallial MGE interneuron development and migration (ZEB2, MAF, MAFB, NXPH1, SST, CXCR4, ACKR3 (CXCR7) and ERBB4) compared to cluster 4 (Figs. 3D, 3E, 13A).
  • Cluster 5 was the intended on-target pallial MGE-type GABAergic interneuron population, representing 86% and 92% of cells in the unsorted lots 1 and 2, respectively (Figs. 3B, 3C). Over 99% of the cells from the sorted preparations of all sequenced lots corresponded to the on-target pallial MGE-type interneuron Cluster 5 (Figs. 3B, 3C).
  • FIGs. 13A-13D Single cell RNA sequencing gene expression patterns in vitro and in the developing human GE.
  • FIG. 13A Dot plot showing top differentially expressed genes in each cluster. The size of the dot represents the fraction of positive cells in that cluster and the shade of the color represents average expression level.
  • FIGs. 13B, 13C Violin plots showing expression of characteristic genes associated with different cell stages and cell types as listed, by sample (FIG. 13B) and by cluster (FIG. 13C).
  • Immature pallial interneurons ultimately further differentiate into transcriptionally heterogeneous subtypes, defined based on their expression of calcium- binding proteins (PV (PVALB), calbindin (CALB1) and calretinin (CALB2)) and neuropeptides (SST, NPY, VIP, CCK, and substance P (TAC1)). It has been shown that SST, NPY, and CCK expression begins in migrating immature interneurons during prenatal development. Thus, expression of these and other MGE- and CGE-derived pallial interneuron subtype markers was examined across samples and clusters (Figs. 13B, 13C). Among the MGE-derived markers, PVALB was not detected (Figs.
  • FIG. 13D LHX6+, MAF+, CXCR4+), a subpallial MGE cluster (FIG. 13D: LHX6+, LHX8+, NKX2-1+) and a striatal MGE-derived interneuron cluster (FIG. 13D: LHX6+, CRABP1+, ETV1+).
  • this dataset included GE progenitors, as well as post-mitotic CGE (FIG. 13D: SCGN+, CALB2+) and LGE (FIG. 13D: MEIS2+, FOXP1+) populations.
  • FIGs. 3F, 3G Comparison of in vitro-derived Day 14 MGE-like progenitors and end-of-process interneurons with human developing GE (GW9-18), using the Shi et al., 2021 dataset as a reference. (FIG. 3F) Prediction scores between 0 and 1 are projected onto day 14 and end-of-process clusters.
  • Each in vitro-derived cell was assigned a prediction score based on the transcriptomic similarity between the query (in vitro cells) and the listed reference GE cell type.
  • FIG. 3G Heatmap showing percentage of cells in each in vitro cluster that are assigned to different GE categories based on prediction scores.
  • Example 5 This non-limiting example shows human ESC-derived pallial MGE-type interneurons persist long-term and functionally integrate in the wild-type and epileptic rodent pallium.
  • Sorted MGE-type interneurons were transplanted into the postnatal mouse brain to characterize their electrophysiological properties within the rodent pallium.
  • FIGS. 4A-4Z Electrophysiological characterization of grafted human interneurons in the rodent pallium.
  • FIG. 4A Cell morphology of GFP-labeled human cells at 2.5 and 5.5 months post transplant (MPT) in the wild-type (WT) mouse cortex.
  • FIG. 4B IHC staining with HNMA and LHX6 confirming the human origin and MGE identity of GFP+ cells.
  • FIGs. 4F-4M Physiological properties, including membrane resistance (FIG. 4F), capacitance (FIG. 4G), resting membrane potential (FIG. 4H), peak intensities for sodium (Na+) and potassium (K+) currents (FIG.
  • P,Q Individual spike amplitudes (FIG. 4P) and inter-spike intervals (FIG. 4Q) recorded from the human cells at 4 and 7.5 MPT.
  • FIGs. 4R, 4S Examples of human interneurons firing evoked aPs at ⁇ 15 MPT in the WT cortex (FIG. 4R) and in the hippocampus (HC, FIG. 4S).
  • FIG. 4T IHC staining of SYN-ChR2-YFP labeled human cells in the epileptic HC ⁇ 15 MPT: ChR2-YFP, HNA and LHX6. Regions 1 and 2 are shown at higher magnification with arrows pointing out examples of human cells (HNA+ LHX6+).
  • FIG. 4U Average sEPSC frequency
  • FIG. 4V Individual sEPSC amplitudes
  • FIG. 4W Inter-event intervals.
  • FIGs. 4X-4Z Blue light stimulation was used to induce inward currents in ChR2-expressing human cells (FIG. 4X), leading to evoked inhibitory postsynaptic currents (eIPSC) that were measured from the host mouse neurons (FIG. 4Y).
  • eIPSC inhibitory postsynaptic currents
  • AP action potentials
  • Immunodeficient NOG mice received an intrahippocampal injection of kainate into the dorsal CA1 region, which induced status epilepticus followed by the development of chronic spontaneous recurrent mesiotemporal seizures.
  • this chronic phase approximately one month after kainate injection, two independent surgeries were conducted to transplant the cells and implant an EEG electrode into the epileptic hippocampus (Figs. 5A, 14A, 14B).
  • animals displayed a typical sclerotic hippocampal pathology, including granule cell dispersion ipsilateral to the kainate injection (Fig. 14B), and had electrographic mesiotemporal seizures at a frequency of 10-15 per 30-minute period (Fig. 14C).
  • FIGs. 5A-5H Overview of the chronic MTLE mouse model and seizure suppression after cell transplantation with interneuron lots 1U and 1S.
  • FIG. 5A Experimental timeline from epilepsy induction to cell transplantation, electrode implantation, EEG recordings, behavioral assays, and histological analyses.
  • FIGs. 5B-5H EEG was recorded at the indicated time points post-transplant to detect electrographic seizure frequency and duration.
  • FIG. 5D Normalized electrographic mesiotemporal seizure frequency for epileptic animals treated with lots 1-U and 1-S.
  • the mean seizure frequency of the vehicle control group is normalized to zero at each respective time point.
  • the individual vehicle or cell-treated animals are plotted as a percent difference from the mean seizure frequency of the respective vehicle control group at 1-2, 5, and 7 MPT.
  • a responder-rate threshold was designated for animals exhibiting >75% reduction in seizure frequency (depicted dashed line). Mann-Whitney test cell vs.
  • FIG. 5E, 5F Raw data corresponding to FIG. 5D. Cumulative duration of seizures (FIG. 5E) and electrographic seizure frequency (FIG. 5F). Mann-Whitney test cell vs. vehicle at respective time point; significant differences are indicated by red asterisks (* P ⁇ 0.05; ** P ⁇ 0.01; *** P ⁇ 0.001). In addition, significant changes within a treatment group vs.
  • FIGs. 5G, 5H Human cells (HNA+) migrated and dispersed throughout the hippocampus. Expression of interneuron subtype marker Somatostatin (SST) (FIG. 5G) and neuronal marker MAP2 (FIG. 5H) is shown at 8.5MPT.
  • FIGs. 14A-14H Reproducible seizure suppression achieved with multiple independent cell lots.
  • FIGs. 14A, 14B Representative images of mice hippocampi, highlighting targeting strategy for three independent surgical procedures. (FIG.
  • FIG. 14A Naive mice were injected with kainate into the rostral right hippocampus (CA1) to induce status epilepticus (SE). Kainate injection site indicated by the yellow target.
  • FIG. 14B Human interneurons, or a vehicle control, were administered throughout the hippocampus in 4-6 deposit sites (targeted coordinates highlighted by blue dots over the H&E stained hippocampal sections at 1 month post status epilepticus. Site of electrode placement is indicated by an arrow.
  • FIG. 14C By 1 month after SE, mice developed spontaneous recurrent seizures. Baseline seizure frequency was stable between vehicle and cell-treated mice directly after transplantation until 2 MPT. (FIGs.
  • FIG. 14F Human cells stained for HNA and SST in the epileptic hippocampus (xxx mark the approximate anterior- posterior (AP) positions of the transplants and a-d mark the approximate AP coordinates of the images shown) as shown here at 8.5 MPT.
  • FIG. 14G Grafted human cells were analyzed by fluorescence in situ hybridization (FISH) using probes against the human housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (hGADPH) and the GABAergic marker glutamate decarboxylase 1 (GAD1). Representative images show cell distribution in the hippocampus with higher magnification examples of the CA1 and CA3 regions.
  • FISH fluorescence in situ hybridization
  • FIG. 14H Images of the hippocampus stained for Vimentin (VIM) and HNA.
  • VIM Vimentin
  • HNA HNA
  • Cryopreserved hESC-derived pallial MGE-type interneurons were thawed and transplanted along the rostrocaudal axis of the hippocampus in multiple deposit sites (Figs. 5A, 14B).
  • Lot 1 unsorted (1-U) and sorted (1-S) batches (Figs. 3A-3G) were evaluated for seizure-modifying activity at 1-2, 5 and 7 MPT. All treatment groups had comparable seizure frequency and cumulative seizure duration at the beginning of the study, 1-2 MPT (Figs. 5D-5F).
  • administering hESC-derived, pallial, MGE-type inhibitory interneuron cells to a subject having seizure activity substantially abolishes seizures in the subject.
  • administering the pallial MGE-type inhibitory interneuron cells to a subject having seizure activity reduces seizure frequency by at least about 75% compared to vehicle control.
  • administering the pallial MGE-type inhibitory interneuron cells to a subject having seizure activity reduces seizure frequency by at least about 75% in at least 60% of the subjects compared to vehicle control.
  • a subject in need of treatment for seizure activity has a hippocampal pathology associated with spontaneous, recurrent seizures.
  • a subject in need of treatment for seizure activity has chronic epilepsy.
  • a subject in need of treatment for seizure activity has a focal onset seizure.
  • a method of treating seizure activity comprises administering a therapeutically effective amount of hESC-derived pallial MGE-type inhibitory interneuron cells to one or more sites in the subject’s hippocampus and/or cortex. In some embodiments, a method of treating seizure activity comprises administering a therapeutically effective amount of hESC-derived pallial MGE-type inhibitory interneuron cells to 1, 2, 3, 4, 5, 6, or more sites in the subject’s hippocampus and/or cortex.
  • Example 7 [0286] This non-limiting example shows human ESC-derived interneurons disperse, innervate the epileptic hippocampus, and express subtype markers of pallial MGE- type GABAergic interneurons.
  • Astrocyte marker GFAP was very rarely observed along the injection tract and never among the dispersed cells, contributing to less than 0.01% of grafted human cells (Figs. 6E (panel viii), 6G). Similarly, virtually no proliferating KI67+ cells were detected (Figs. 6E (panel ix), 6G).
  • Neural stem cell and astrocyte marker Vimentin (VIM) was detected in the vehicle-treated ipsilateral hippocampus (Fig. 14H), likely labeling endogenous reactive astrocytes.
  • VIM staining was markedly reduced in the cell-treated epileptic hippocampus, and VIM was not expressed by the human cells (Fig. 14H), further confirming the lack of neural progenitors from the graft.
  • FIGs. 6A-6M Histological characterization of interneuron lots 1-U and 1-S in the epileptic hippocampus. (FIGs.
  • FIG. 6A, 6B Expression of immature neuronal marker doublecortin (DCX) (FIG. 6A) and MGE interneuron marker somatostatin (SST) (FIG. 6B) in human cells (HNA) at 1, 4 and 8.5 MPT.
  • FIG. 6C Human-specific axonal marker hTAU showing transplanted cell processes in the rostral to caudal epileptic HC (panels a-d), counter-stained with NEUN.
  • FIG. 6D Grafted human cells were analyzed by fluorescence in situ hybridization (FISH) using probes against the human housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (hGADPH) and the GABAergic marker glutamate decarboxylase 1 (GAD1). Representative image shows cell distribution in the rostral hippocampus with a higher magnification example of the hilus (1).
  • FISH fluorescence in situ hybridization
  • FIG. 6E Representative IHC images showing co-labeling of human cells (HNA+) with on-target MGE interneuron markers in green: LHX6, SST, NPY, PV as well as perineuronal nets marker WFA associated with fast spiking PV-type interneurons.
  • FIG. 6F Quantification of human cell persistence (FIG. 6F) and percent of human cells expressing GAD1 mRNA, and LHX6, SST, KI67, OLIG2 and GFAP proteins (FIG. 6G).
  • the hESC-derived, differentiated cells are enriched for cells expressing at least LHX6, ERBB4, and GAD1 compared to undifferentiated hESCs or MGE-type progenitor cells. In some embodiments, at least 98% of the differentiated cells express GAD1.
  • Example 8 This non-limiting example shows that human pallial MGE-type interneurons demonstrate dose-dependent seizure suppression. [0292] To help define the efficacious dosing range, lot 2 unsorted (2-U) and sorted (2-S) cells (Figs.
  • 3A-3G were evaluated across a series of doses: lot 2-U at 25K, 50K, 200K, and 1.5M cells per hippocampus, and lot 2-S at the two highest doses only.
  • the escalating cell dose treatment cohorts had separate vehicle control groups (Low/Mid/High) to match larger delivery volumes.
  • mesiotemporal seizure frequency was suppressed in a dose-dependent manner. While 25K and 50K cell doses did not significantly reduce mean seizure frequency, statistically significant seizure suppression was achieved with 200K and 1.5M cell doses at 7 MPT (Fig. 7A).
  • FIGs. 7A-7J Human interneuron dose-response activity in the MTLE model.
  • FIG. 7A Four doses of hESC-derived interneurons (lot 2-U) were transplanted into the MTLE mouse model: 25K, 50K, 200K or 1.5M cells/hippocampus. The two higher doses were also evaluated with sorted cells (lot 2-S). Vehicle group mean seizure frequency is normalized to zero. The escalating cell dose treatment cohorts had separate vehicle control groups to match larger delivery volumes. All data are median and single dots indicate individual animals. Significant differences between cell vs. vehicle groups at each time point are indicated by asterisk (P ⁇ 0.05), Mann-Whitney test (200K and 1.5M dose groups vs. respective vehicle groups). Kruskal Wallis test between 25K and 50K vs. corresponding vehicle group was not significant at any of the time points.
  • FIGs. 7B-7D Histology panel shows cell persistence, distribution, and fate in the epileptic hippocampus at the four doses of human interneurons from lot 2-U at 8.5 MPT.
  • FIG. 7B Immunohistochemical detection of persisting HNA+ human cells.
  • FIGs. 7C, 7D Higher magnification images of the corresponding dentate gyrus. Persisting human cells expressed MGE interneuron markers LHX6 (FIG. 7C) and SST (FIG. 7D).
  • FIG. 7E-7J Quantification of human cell persistence and fate of lots 2-U and 2-S. The total number of persisting human cells at 8.5 MPT and rate of persistence as a percentage of the initial dose.
  • FIGs. 7F-7I Quantification of the total number of LHX6+ human cells and the percentage of human cells expressing HNA (FIG. 7E), LHX6 (FIG. 7F) and SST (FIG. 7G) at 8.5 MPT.
  • FIG. 7H The rate of human cell persistence as a percentage of HNA over the initial dose.
  • suppression of seizure by administering hESC- derived pallial MGE-type inhibitory (e.g., GABAergic) interneuron cells to a subject having seizure activity is dose dependent.
  • at least about 60%, or on average about 80% of persistent cells in the transplanted hippocampus to which hESC-derived pallial MGE-type inhibitory (e.g., GABAergic) interneuron cells were transplanted are MGE-type GABAergic interneurons.
  • At least about 5%, or on average about 20- 55% of persistent cells in the hippocampus to which hESC-derived pallial MGE-type inhibitory (e.g., GABAergic) interneuron cells were transplanted are cortical interneurons expressing SST.
  • hESC-derived pallial MGE-type inhibitory e.g., GABAergic
  • Example 9 This non-limiting example shows Human pallial MGE-type interneuron transplantation reduces dentate granule cell dispersion in the epileptic hippocampus.
  • One hallmark of MTLE is the characteristic sclerotic pathology of the affected hippocampus.
  • the intrahippocampal kainate mouse model recapitulates sclerotic hippocampal dentate granule cell (GC) dispersion and the overall neurodegeneration seen in patients.
  • GC dentate granule cell
  • the width and the area of the GC layer were measured in the rostral hippocampus of naive mice, vehicle-treated epileptic mice, and cell-treated epileptic mice that received different doses of lots 2-U and 2-S (Figs. 8A-8H). All cell doses significantly reduced GC layer width compared to vehicle treatment (Fig. 8G). There was also a dose-dependent effect on the GC layer area, with more significant reduction observed at the two higher doses (Fig. 8H).
  • FIGs. 8A-8L Epileptic hippocampal pathology, behavioral outcome and animal survival after human interneuron transplantation.
  • FIGs. 8A-8H Granule Cell Dispersion Analysis: DAPI labeling shows the granule cell (GC) layer in an age- matched naive mouse (FIG. 8A), epileptic vehicle-treated mouse with typical pathological GC dispersion at 8.5 MPT (FIG. 8B) and epileptic cell-treated mice transplanted with 25K, 50K, 200K and 1.5M human cells/hippocampus of lot 2-U, respectively (FIGs. 8C-8F) at 8.5 MPT.
  • FIGs. 8A-8H Granule Cell Dispersion Analysis: DAPI labeling shows the granule cell (GC) layer in an age- matched naive mouse (FIG. 8A), epileptic vehicle-treated mouse with typical pathological GC dispersion at 8.5 MPT (FIG. 8B) and epileptic cell-treated mice transplanted with 25
  • GC dispersion was quantified by measurements at -1.8 mm from Bregma, which is the rostrocaudal level of the kainate injection: the average GC layer width (FIG. 8H) was measured at three places, as illustrated with white lines in B, and GC layer area (FIG. 8H) was measured as illustrated with a white boundary in FIG. 8B. All data are mean ⁇ SEM. Three vehicle groups were used to match the delivery volumes of the respective cell doses, labeled as Vehicle-Low, Vehicle-Mid and Vehicle-High. The Kruskal Wallis statistic, followed by Dunn’s test, was significant between cell and vehicle groups at all doses for both lots, 2-U and 2-S (P ⁇ 0.05). (FIGs.
  • a subject having seizure activity exhibits an epileptic hippocampal pathology. In some embodiments, a subject having seizure activity exhibits an increase in the width or area of the granule cell layer at the level of the epileptogenic lesion.
  • a subject having seizure activity exhibits an increase in granule cell dispersion at the level of the hippocampal sclerosis.
  • administering hESC-derived pallial MGE-type inhibitory (e.g., GABAergic) interneuron cells to a subject having seizure activity reduces the width or area of the granule cell layer at the level of the hippocampal sclerosis.
  • administering hESC-derived pallial MGE-type inhibitory (e.g., GABAergic) interneuron cells to a subject having seizure activity reduces granule cell dispersion at the level of the hippocampal sclerosis.
  • Example 10 This non-limiting example shows that improved spatial memory, increased epileptic animal survival, and no adverse effects are detected after human pallial MGE-type interneuron transplantation.
  • Dizziness, sedation, and ataxia are the most common adverse effects of systemically administered GABA-potentiating ASDs. It is possible that increasing neural network inhibition by transplanting high doses of GABAergic interneurons could lead to sedative effects as well. Therefore, a modified Irwin screen was performed to evaluate potential adverse effects of cell treatment with the highest dose (1.5M/hippocampus) of lot 2- U cells in epileptic mice.
  • the testing battery included assays for body posture and appearance, excitability, and spatial locomotion (Fig. 8M).
  • FIGs. 8M-8Q (FIG. 8M) A modified Irwin screen was performed to evaluate potential side effects of human GABAergic interneuron administration. Data are only shown for the highest tested dose of 1.5 M cells/hippocampus of lot 2-U.
  • FIG. 8N An Open Field (OF) test was performed to measure general anxiety, spatial locomotion and travel velocity.
  • FIG. 8O Y maze test was performed to measure spatial memory.
  • Example 11 This non-limiting example summarizes the results of Examples 2-10. [0305] Worldwide, about 70 million people suffer from epilepsy, and over one- third have seizures that are drug-resistant. Despite the development of next-generation small molecule antiseizure drugs, the proportion of people with pharmacoresistant epilepsy has not changed significantly in decades. Drug-resistant MTLE patients with a single, well-defined seizure focus in the temporal lobe may be eligible for a temporal lobe resection or laser ablation surgery. However, these surgeries are destructive to tissues surrounding the seizure focus and can have irreversible adverse cognitive effects.
  • Pallial lineage purity was further enriched to >99% using an ERBB4-based purification step.
  • ERBB4-based purification step Upon detailed investigation of long-term engraftment, preliminary safety, and disease- modifying activity following intra-hippocampal administration into a chronic mouse model of MTLE, both the sorted and unsorted cell lots were comparable in terms of efficacy and safety, suggesting that >85% pallial-type interneuron purity is sufficient, and ⁇ 15% subpallial neuron content is tolerable, in the MTLE model.
  • the intrahippocampal kainate mouse model of chronic focal epilepsy was chosen because of its high face validity to hallmark symptoms of clinical MTLE, i.e. mesiotemporal seizures and hippocampal sclerosis.
  • Example 12 This non-limiting example shows cryopreservation of a cellular composition of pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells, and cell dose preparation post-thaw.
  • MGE-type inhibitory e.g., GABAergic
  • Cryopreserved cells were thawed rapidly, 0.5 – 5 mins at 30 – 40°C, and rehydrated slowly, 0.5 - 2 mins/mL, in thaw medium containing DNase (500-2000 units/ mL), supplements and sodium ions (100 – 600 mM) to scavenge free radicals while maintaining high osmolarity in order to reduce the risk of rapid cell expansion and cellular membrane damage.
  • DNase 500-2000 units/ mL
  • sodium ions 100 – 600 mM
  • Example 15 shows that the viability of cells appears to be stable after an extended period of holding up to 120 hrs (when measured by Trypan blue membrane exclusion and NC-200).
  • the cells were then reformulated in a final cell delivery vehicle containing a buffered solution at physiologic pH.
  • the delivery vehicle contained supplements, lipid polymers, poloxamers, and/or MRI contrast agents, such as gadolinium, to enable visualization of cell delivery under intraoperative MRI.
  • Example 13 This non-limiting example shows preparation and use of the cell delivery system for administering a cellular composition of pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells to a subject.
  • pluripotent stem cell-derived, pallial, MGE-type inhibitory e.g., GABAergic
  • a cannula was loaded with a suspension of pluripotent stem cell-derived, pallial, MGE-type inhibitory interneuron cells (NRTX-1001), and was not subject to further changes in cell concentration due to gravity sedimentation of cells. As such, cells suspended at a sufficiently high cell concentration in a final cell delivery vehicle formulation can be stably held in the cannula at different orientations for an extended period of time (0.5-96 hours) during surgical preparation for transplantation.
  • the delivery system was prepared as follows (FIG. 24): (1) A cannula was attached to a syringe loaded with a chase vehicle (including a vehicle with identical composition to the cell-containing vehicle).
  • the cannula was primed with the cell-free chase vehicle delivered from the syringe.
  • the concentrated cell suspension in a reduced volume was loaded into the cannula volume from the proximal tip (closer to the patient-facing end) of the cannula by drawing the syringe plunger, and was subsequently efficiently expelled from the outlet of the cannula by the cell-free chase vehicle, whereby the cell-free chase vehicle filled the remaining volume of the cannula and syringe, without the need to completely fill the entire cannula and syringe volume with the cell suspension.
  • a syringe pump was used to control the volume and rate of cell delivery.
  • the delivery system achieved consistent deposition, by cell number and volume delivered, of freshly thawed NRTX-1001 cells as well as of thawed NRTX-1001 cells that were held for 24 hours before depositing (FIG. 16A, left and center panels).
  • the deposited cells retained high viability when freshly thawed and after a 24-hour cell hold (FIG. 16A, right panels).
  • the clinical dose of cells and volume were delivered consistently (FIG. 16B, top panels).
  • the cells in a clinical dosing ranges were delivered with a consistent flow rate, with nominal back pressure. (FIG. 16B, bottom panels).
  • the composition was also stable after extended hold periods in the cannula. Cryopreserved cells were thawed (see Example 12) and went through a post-thaw hold period, either as a diluted cell suspension at room temperature overnight, or as a concentrated cell suspension for 72 hours (FIG. 17, time lines). After the post-thaw hold, the cells were loaded in a cannula and held for different lengths of time at room temperature before delivery. Both the volume and cell concentration delivered from the cannula remained sufficiently stable over increasing hold times in the cannula, up to 10 hours or longer (FIG.
  • Detectable structural and metabolic alterations can be studied longitudinally using magnetic resonance imaging (MRI), positron emission tomography (PET) and magnetic resonance spectroscopy (MRS) to evaluate changes in the epileptic brain before and after cell therapy.
  • MRI magnetic resonance imaging
  • PET positron emission tomography
  • MRS magnetic resonance spectroscopy
  • longitudinal MRS data can be acquired to evaluate levels of metabolites in brain regions of interest, including N- acetylaspartate (NAA) for neuronal viability, myoinositol for inflammation and gliosis, glutamate for excitatory neurotransmitter proxy of neural excitation, and ⁇ -Aminobutyric acid (GABA) for inhibitory neurotransmitter proxy of therapeutic activity of the inhibitory interneuron cell therapy.
  • NAA N- acetylaspartate
  • GABA ⁇ -Aminobutyric acid
  • Example 15 This non-limiting example shows hESC-derived, pallial, MGE-type GABAergic interneurons retain MGE pallial interneuron fate after transplantation into a host brain.
  • MTT single nuclei RNA sequencing
  • Neonate mouse cortex was transplanted with human cells (obtained as described in Example 2) and dissected at 1 MPT, 3-4 MPT, 6-7 MPT, 12 MPT and 18 MPT.
  • Cortical tissues were processed to isolate nuclei and stained with an antibody against human nuclear antigen to enable unbiased enrichment of all the grafted human cells by fluorescence activated nuclei sorting (FANS). Sorted nuclei were captured using microfluidics controller (10X Genomics), barcoded and processed for snRNAseq. Following alignment, mapping and quality controls to remove contaminating mouse nuclei, a total of 114,655 human single nuclei were analyzed from 4 independent lots at 5 time points.
  • FIG. 19A shows the results from independent Unsupervised prediction algorithm, comparing hESC-derived pIN gene expression with endogenous human pINs from adult M1 cortex. Prediction scores between 0 and 1 are plotted for each cell based on the transcriptome-wide similarity in gene expression between the query (in vitro-derived cells) and the reference (in vivo subclasses).
  • FIG. 19C shows a dot plot for key genes that define different cell categories, including general markers of neurons, GABAergic neurons, MGE, MGE subpallial neurons, and other off target regions and cell types, including preoptic area (POA), CGE, LGE, neuronal progenitors, cell cycle, pluripotent, as well as genes associated with glial cells, glutamatergic neurons (Glu), dopaminergic neurons (DA), serotonergic neurons (5HT) and cholinergic neurons (Ach). Feature plots showing gene expression across cells are shown in FIGs.
  • FIG. 19D-19F Darker shade correspond to higher expression level. Markers shown include genes that are expressed and maintained in MGE-type pINs postnatally and into adulthood (FIG. 19D); genes that are enriched in subsets of MGE-type pINs (FIG. 19E); genes that are enriched in subsets of CGE-type pINs (FIG. 19F). Subclass categories of transplanted human cells based on prediction and cluster marker analyses are shown in FIG. 19G. FIG.
  • Projection of hESC-derived MGE pIN subclasses onto human prenatal-adult prefrontal cortex interneuron dataset shows overlap with MGE-derived PV, SST and NPY cortical interneuron (cIN) populations and not any of the CGE-derived cIN populations (FIG. 19I).
  • Example 16 This non-limiting example shows interim results of an open label Phase I/II Clinical Study of NRTX-1001 for Drug-resistant MTLE.
  • Two adult subjects with chronic unilateral MTLE were administered a single dose of NRTX-1001 in the affected, sclerotic right hippocampus with MRI guidance.
  • the subjects were concurrently being treated with anti-seizure medication, including one or more benzodiazepines.
  • the frequency of focal seizures experienced by the subject was determined based on self-reported number of seizure events.
  • a single administration of the cellular composition reduced the frequency of overall seizures by about 95% from a pre-dosing baseline of about 32 per month, over at least 13 months after administration (FIG. 20, left panel). This included a 95% reduction in focal aware seizures, and a 96% reduction in focal impaired awareness seizures.
  • Subject #2 a single administration of the cellular composition reduced the frequency of overall seizures by about 95% from a pre-dosing baseline of about 14 per month, over at least 8 months after administration (FIG. 20, right panel). This included a 100% reduction in focal aware seizures, and a 63% reduction in focal impaired awareness seizures.
  • Subject #1 was further monitored using hippocampal MR spectroscopy to assess levels of various biomarker metabolites (normalized to creatine) (FIG. 21). The levels of each marker were assessed in the right (treated) hemisphere. The level of myoinositol, a marker of neuroinflammation, showed a consistent trend of reduced levels after administration (FIG. 21, left panel).
  • N-acetylaspartate a marker of neuronal viability
  • the level of N-acetylaspartate was consistently higher in the treated hemisphere after administration (FIG. 21, center-left panel). Further, the level of GABA was increased in the treated hemisphere after administration of NRTX-1001 (FIG. 21, right panel).
  • the treated subjects were further assessed for cognitive ability. The subject’s cognitive ability was tested for word retrieval (Boston Naming Test), verbal memory (Rey Auditory Verbal Learning Test (RAVLT)), and visuo-spatial memory (Brief Visuospatial Memory Test (BVMT)) at intervals after administration and compared to baseline.
  • Subject #1 showed improvement in neurocognitive scores in all tests by 12 months after administration (FIG. 22, left panel). Word retrieval improved by 6 months after administration. For verbal memory, delayed recall in the RAVLT improved by 6 months, and immediate recall improved by 12 months. Visual memory assessed by delayed recall and percent retained in the BVMT improved by 6 months.
  • Subject #2 showed improvement in neurocognitive scores in verbal memory, compared to baseline by 6 months after administration (FIG. 22, right panel). Word retrieval remained within normal range over 6 months. For verbal memory, delayed recall in the RAVLT improved by 6 months, and immediate recall remained within normal scores.
  • Example 17 This non-limiting example shows effects of transplanted human pallial MGE-type interneurons in a model of Alzheimer’s disease (AD).
  • AD Alzheimer’s disease
  • Hyperexcitability in 5xFAD AD model is thought to sensitize the effect of urethane in theta oscillation duration but not frequency. Further, reduction of gamma activity by riluzole is more prominent in AD models.
  • 5xFAD mice were implanted with hippocampal electrodes and treated with urethane or riluzole. [0339] As shown in FIG.
  • urethane injected in vehicle-treated (“V”) 5xFAD mice showed a significant effect on theta duration when compared to animals transplanted with hESC-derived interneurons (“C”). No effects were observed in theta peak frequency (FIG. 23A).
  • FIG. 23B a significant reduction in slow gamma peak frequency was induced by riluzole in vehicle-treated 5xFAD animals (“V”) but not in animals transplanted with hESC-derived interneurons (“C”). No effects were observed in the time spent exploring new objects (FIG. 23B).
  • Example 18 [0341] This non-limiting example provides an embodiment of a method of treating seizure activity in a subject.
  • a population of MGE-type GABAergic neurons is differentiated from human embryonic stem cells as described in Example 2 (without sorting).
  • the EOP neurons are sorted for NRP2.
  • the sorted population has higher proportion of cells expressing LHX8 and not expressing ERBB4 compared to the unsorted population, and thus is enriched for the subpallial lineage.
  • the population of MGE-type GABAergic neurons enriched for the subpallial lineage is administered to a subject suffering from focal onset seizures. After administration, the frequency of focal onset seizures is reduced compared to before administration.
  • Example 19 This non-limiting example provides an embodiment of a method of treating seizure activity in a subject.
  • a population of MGE-type GABAergic neurons is differentiated from human embryonic stem cells as described in Example 2 (without sorting).
  • the cells expressing ERBB4 are sorted away from the EOP neurons.
  • the resulting population has higher proportion of cells expressing LHX8 and not expressing ERBB4 compared to the unsorted population, and thus is enriched for the subpallial lineage.
  • the population of MGE-type GABAergic neurons enriched for the subpallial lineage is administered to a subject suffering from focal onset seizures. After administration, the frequency of focal onset seizures is reduced compared to before administration.
  • Example 20 [0347] This non-limiting example provides an embodiment of a method of treating seizure activity in a subject.
  • a population of MGE-type GABAergic neurons is differentiated from human embryonic stem cells as described in Example 2 (without sorting), except MEK inhibition is omitted.
  • the EOP neurons have a higher proportion of cells expressing LHX8 and not expressing ERBB4 compared to neurons differentiated with MEK inhibition, and thus are enriched for the subpallial lineage.
  • the population of MGE-type GABAergic neurons enriched for the subpallial lineage is administered to a subject suffering from focal onset seizures. After administration, the frequency of focal onset seizures is reduced compared to before administration.
  • Example 21 Stable graft composition from 1 to 18 months post-transplantation, comprised of PVALB and SST MGE interneuron subclasses
  • PVALB and SST MGE interneuron subclasses To quantitatively characterize human cell fate and long-term graft composition in the brain, five different lots were transplanted into neonate cortex and cortical samples were collected at 1, 3-4, 6-7, 12 and 18 months post-transplant (MPT), followed by nuclei isolation and snRNAseq. To enrich the proportion of human cells prior to sequencing, an antibody against human nuclear antigen (HNA) was used, enabling unbiased selection of all the human cells based on HNA fluorescence-activated nuclear sorting (FANS) (FIG. 25A).
  • HNA human nuclear antigen
  • FIG. 25C, 25D; FIG 26D To objectively interpret transplanted cell identity in terms of major cell classes, the human adult whole brain snRNAseq reference dataset was used, which sampled over 100 anatomically distinct brain regions derived from telencephalon, diencephalon, midbrain, hindbrain, and anterior spinal cord 42 . In this dataset, 30 neuronal and non-neuronal superclusters corresponding to major cell classes were defined, providing a diverse transcriptional reference, to which transplanted cells were compared.
  • Cluster 10 was distinguished by co- expression of ADARB2 along with MGE IN markers (SOX6, LHX6, SST, RELN) and several other genes that appeared in the LHX6/ENC1/LHX8 pre-transplant cluster (FIG. 25C, 25D, 25I, 25N).
  • MGE IN markers SOX6, LHX6, SST, RELN
  • ADARB2 is a common marker of CGE-derived INs
  • no other CGE-associated markers SP8, SCGN, VIP, HTR3A, CCK, CALB2, LAMP5 were expressed (FIG. 25D, 25I).
  • ERBB4 is also expressed in this population (FIG.
  • cluster 10 might represent an unusual, perhaps human-specific MGE IN cell type that is not well annotated in the reference datasets. This idea is supported by identification of some unconventional interneuron populations, including double-positive ADARB2/LHX6 cells that are expanded in the human neocortex compared to the rodent, and for which classification based on developmental origin (MGE-derived) does not match with the classification based on the adult transcriptional profile (CGE-like) 43-47 . Thus, cluster 10, henceforth designated as “ADARB2” represents a minor transcriptionally distinct GABAergic population within human grafts.
  • SST lineage-associated markers including SST, RELN, BCL11A, NPAS1, NPAS3, SYNPR, GRIN3A and GRIA3 were enriched in the predicted SST population (FIG. 25I, 25N).
  • the predicted SST NPY population was characterized by co-expression of SST with NPY, NOS1, TACR1, TOX and others (FIG. 25I, 25N).
  • none of the transplanted cells had strong prediction scores for MGE-derived fast-spiking Chandelier or Lamp5/Lhx6 neurogliaform cells, or any of the CGE-derived subclasses, consistent with lack of corresponding markers (FIG. 25H, 25I).
  • graft composition could be quantified for all the lots and time points. It was determined that human hMGE-pIN grafts consisted of ⁇ 20-40% PVALB, 60-80% SST, 5-10% NPY and ⁇ 5% ADARB2 subclasses (FIG. 25J-25L). The range was attributed to the variation among biological replicates corresponding to independent manufacturing lots (FIG. 25L). Average composition was stable from 3-4 MPT and beyond (FIGs. 25K-25L), but from 1 to 3-4 MPT a small decrease in PVALB cells for a given batch was observed (FIG. 25M).
  • FIG. 26I GABAergic marker glutamate decarboxylase 1 (GAD1) was used as a positive control, as it should be expressed by all the subclasses (FIG. 26J), and this was corroborated with FISH (FIG. 26K, 26L).
  • GABAergic marker glutamate decarboxylase 1 GABAergic marker glutamate decarboxylase 1 (GAD1) was used as a positive control, as it should be expressed by all the subclasses (FIG. 26J), and this was corroborated with FISH (FIG. 26K, 26L).
  • SLIT2 expression is stronger in PVALB than in other interneuron populations in vivo (FIG. 26H) and in the transplanted cells (FIG. 26J), although there are cells that co-express SLIT2 and SST (FIG. 25I).
  • SST transcript levels increased steadily with time in both the SST and SST NPY subclasses, and it took 12 MPT to reach robust expression levels in the SST subclass (FIG. 26J, 26L).
  • This incredibly prolonged neurochemical maturation of human interneurons explains why immunostaining approaches against PVALB and SST antigens greatly underestimate both populations, especially at earlier time points 1 , and why the transcriptomic approach relying on thousands of genes is much more sensitive.
  • the NPY transcript was already expressed robustly at 1 MPT, enabling early detection of this population with the FISH probe (FIG. 26J-26L).
  • Example 22 Transplantation environment triggers expression of synaptic genes enabling rapid cell fate identification [0359] The rapid post-transplant specification and robustness of the prediction model was leveraged to ask whether cell fate could be discerned in vitro without transplantation, perhaps after extended culture, and whether it is possible to discern cell fate even sooner than 1 MPT—thus addressing the effects of timing and environment.
  • Nuclei were sequenced from one lot (010519S1) immediately post-thaw, after a month of in vitro co-culture with astrocytes (30 DIV) and 14 days post-transplantation (14 DPT). These new samples were integrated with pre-transplant whole cell and 1 MPT data from the same lot to identify similar cell types (FIG. 27A; FIG. 28A). Clustering all the samples together enabled guided subclass assignments for the in vitro cells (FIG. 27B; FIG. 28B) and revealed the transcriptomic relationship between pre-transplants and post-transplant populations (FIG. 27C).
  • Example 23 Cell development is characterized by major transcriptional changes during the first 3 MPT followed by gradual unfolding of gene modules involved in regulation of synaptic transmission and membrane potential [0361]
  • hMGE-pIN grafts are comprised of multiple PVALB and SST subtypes, including Basket cells, non-Martinotti, Martinotti and Long-projecting SST cells [0364] Pallial interneurons exhibit remarkable diversity, with 72 transcriptionally defined subtypes conserved across adult cortical areas 48 . To assess how many subtypes are represented within hMGE-pIN grafts, cluster correlations to each other were analyzed.
  • cluster 9 is very distinct, whereas clusters 5 and 1 are highly correlated to each other (FIG. 30A), suggesting at least two PVALB populations.
  • Cluster 7 is correlated with both PVALB and SST subclasses, consistent with overlapping marker expression gradients (FIG. 25I).
  • SST NPY clusters 0, 4, 3, 2, and 8
  • ADARB2 clusters 6
  • ADARB2 ADARB2
  • Cluster 7 (PV/SST) partially overlapped with three human clusters, including two deep layer non-Martinotti SST clusters and L6 Th+ SST/PV population, confirming that this cell population likely shares the properties of both subclasses. Of note, this cluster was not counted towards PVALB (FIGs. 25J-25M), even though some of the cells could be fast-spiking.
  • Clusters 0 and 4 (SST1) overlapped with a few human SST clusters corresponding to deep layer non-Martinotti cells (FIGs. 30B, 30C).
  • Clusters 3, 2 (SST2) and 8 (SST3) overlapped with deep and superficial layer T-shaped Martinotti human clusters, respectively (FIGs. 30B, 30C).
  • hMGE-pINs grafts consist of diverse transcriptionally defined subtypes, including upper (PV1) and lower (PV2) FS Basket cells ( ⁇ 21% total), SST/PVALB cells ( ⁇ 7%), non- Martinotti (SST1, ⁇ 32%), Martinotti (SST2 and SST3, ⁇ 33% total) and LRP (NPY, ⁇ 6%) SST cells, as well as ADARB2 cells ( ⁇ 1%) (FIGs. 30C, 30D).
  • PV1 upper layer FS Basket cells
  • TFs Transcription factors
  • CAMs cell adhesion molecules
  • VFG. 30F voltage-gated ion channels at the cell membrane
  • SST interneuron subtypes were enriched for NPAS1, NPAS3 (non Martinotti), and ETV1, BCL11A (Martinotti), whereas the SST NPY Long-range projecting population was marked by TOX enrichment (FIG. 30F; FIG. 25N). These expression patterns are consistent with expression patterns observed endogenously in mouse and human cINs 43, 49 , providing further evidence for the diversity of subtypes in the grafts. Finally, the ADARB2 subtype was marked by specific enrichment for LDB2 TFs (FIG. 30F).
  • Kv channels and regulatory subunits exhibited subtype-specific enrichments, with notable examples associated with fast-spiking interneurons such as KCNC1 and KCNC2 (encoding Kv3) and KCNA2, KCNA7, KCNAB1, KCNAB2, and KCNAB3 (encoding Kv1-type potassium channel and modulatory subunits) (FIGs. 30F, 30G).
  • KCNC1 and KCNC2 encoding Kv3
  • KCNA7 KCNA7
  • KCNAB1, KCNAB2, and KCNAB3 encoding Kv1-type potassium channel and modulatory subunits
  • Martinotti cells most clearly exemplified by SST3, showed distinct enrichment in several CaV genes, including CACNG7, CACNA1G, CACNG8, and CACNA1C (FIGs. 30B, 30F).
  • FIG. 31A To assess these features in vivo, cells were transplanted into the neonatal (P1-P2) mouse cortex at a single dose per hemisphere (FIG. 31A) and analyzed their engraftment at different postnatal times using immunohistochemistry (IHC). Human interneurons extensively migrated rostro-caudally (>2.4mm) and persisted up to 18 MPT (FIGs. 31B- 31D), while maintaining high levels of LHX6 expression.
  • IHC immunohistochemistry
  • LRP axons usually traveled horizontally, parallel to the corpus callosum, and these cells were commonly identified by their expression of NPY and SST/NOS1 (FIGs. 31L, 31M). Furthermore, NPY+SST+ axon projections were observed along the hippocampus, near the nucleus accumbens in the striatum, and traveling contralaterally through the corpus callosum in the forebrain midline (FIGs. 31N-31P). On the other hand, ERBB4-expressing cells were negative for SST and displayed a multipolar dendritic morphology (FIG. 31Q) with extensive human SYP-expressing axonal arborizations covering nearby cells, reminiscent of Basket cells (FIG. 31R).
  • inhibitory synapses were identified (as shown by the close contact between human presynaptic SYP and postsynaptic Gephyrin), which were formed by SST+ hMGE-pINs that targeted the distal dendrites of pyramidal cells (labeled by Pex5L, FIG. 32F). These axonal boutons expressed SST as well as SYNPR, and GRIN3A (FIGs. 32G, 32H), which have been suggested to play a role in SST+ cell synapse formation and specification 59 . Furthermore, axonal expression of the SST2 cluster marker ARHGAP6 (FIG.
  • Rho GTPase activating protein family suggested to have an important role in human synaptogenesis was found 60 .
  • synaptic formation by Basket cells in layer IV was analyzed. Human axons surrounding the soma of endogenous neurons, with several forming synapses were observed, as shown by human SYP and the host postsynaptic marker GabaR1 (FIGs. 32J, 32K).
  • Example 26 Human pallial interneuron viability, persistence, distribution, and fate are stable post- transplantation following extended hold periods in vitro post-thaw [0373]
  • FIG. 34A Single-cell RNA sequencing analysis of hPSC-derived GABAergic neurons at 1 month and 4 months post-transplantation into rodent brains revealed no off-target cell types, off-target gene expression, or significant differences in gene expression patterns: (FIG. 34A) The gene expression profiles and composition were consistent between cells stored at 2-18°C for 48-72 hours and the control, and (FIG. 34B) were comparable between the 1-month and 4-month post-transplantation time points (FIGs. 35A-35B).
  • Example 27 Spontaneous calcium transient activity from human pallial interneurons (hpIN) in vitro
  • Human pallial interneurons (hpIN) co-cultured with mouse astrocytes displayed robust spontaneous action potential activity detected using calcium imaging, within 17 days of in vitro culture post-thaw.
  • Addition of different neurotransmitter receptor antagonists demonstrated that the calcium activity was mediated by mechanisms independent of GABAA or GABAB receptors using Picrotoxin and Saclofen, respectively, and was also independent from glutamate receptors AMPA and NMDA using NBQX and AP-5, respectively.
  • Example 28 Multi-electrode array analysis of co-cultured hiPSC derived glutamatergic neurons and mouse primary astrocytes with or without human GABAergic pallial interneurons (hpIN) [0376] In order to evaluate how human pallial interneurons (hpIN) can integrate in a neuronal network and influence network activity, hpIN were co-cultured in vitro with mouse astrocytes and commercially available hPSC derived glutamatergic neurons from two different sources: Cell Dynamics Incorporated (CDI Gluta) or BitBio (ioGluta).
  • CDI Gluta Cell Dynamics Incorporated
  • BitBio ioGluta
  • Example 29 Evaluation of disease modifying activity of human pallial interneurons post- administration into a rodent model of mesial temporal lobe epilepsy
  • a modified open field protocol using an arena of 40 cm x 60cm was run at 6 months post-transplant (FIGs. 38A-38B).
  • no significant difference in time spent in the center was observed between NRTX-1001 treated epileptic mice and na ⁇ ve mice.
  • Another behavior test assessing anxiety is Another behavior test assessing anxiety.
  • epileptic mice exhibit hippocampal dentate granule cell dispersion, a common feature of mesiotemporal sclerosis in human MTLE, that is significantly greater than in age-matched na ⁇ ve mice.
  • NRTX-1001 human pallial interneuron treated epileptic mice have significantly reduced granule cell dispersion compared to epileptic mice injected with vehicle (FIGs. 39A-39D).
  • NRTX-1001 is well tolerated in this patient population.
  • the impact of NRTX-1001 on cognition and quality of life is being tested by having the patients complete the following brief battery of neuropsychological tests prior to administration of NRTX-1001, and at 6-months, 9-months, 12-months, 18-months, and 24- months following the surgical administration of NRTX-1001:
  • Word naming via Boston Naming Test (BNT) which is a test that is sensitive to detecting compromised lexical retrieval abilities and aphasia through visual confrontation naming.
  • Verbal episodic memory via the Ray Auditory Verbal Learning Test (RAVLT), which is a measure of a person's ability to encode, store, and recover verbal information in different stages of immediate memory.
  • Visuospatial episodic memory via the Brief Visuospatial Memory Test - Revised (BVMT-R), which is a neuropsychological evaluation that measures immediate visual learning, delayed visual memory and recognition.
  • QOLIE-31-P Quality of Life in Epilepsy Inventory: contains seven multi-item scales that assess emotional well-being, social functioning, cognitive functioning, seizure worry, medication effects, and overall quality of life (note that the QOLIE-31-P test is administered at baseline, 6-, 12-, 18-and 24-month visits).
  • Subject 101-001 showed a transient decline in the total BNT score that was not clinically significant and later resolved. Subject 101-001 also demonstrated no significant change from baseline on other neurocognitive tests and a significant increase in QOLIE-31-P at 12- and 18-month visits.
  • the third subject (115-001) has 12-months of data. Subject 115-001 showed a decreased BVMT delayed recall score at 12-months that was not clinically significant and did not decline on other tests. This subject showed a numerical increase in QOLIE-31-P at the 12-month visit.
  • the fourth subject (107-001) showed a decreased BVMT delayed recall at 9-months and decreased BNT score at the 6-month visit that were not clinically significant but had a numerically increased QOLIE-31-P score at the 6-month visit.
  • the fifth subject (104-001) showed no significant decline on any parameter and showed a significant numerical increase on BNT and RAVLT scores at 6- and 9-month visits.
  • Efficacy data available from 5 subjects treated at the low dose level (Cohort 1) in the Phase 1 portion of the study suggest that NRTX-1001 treatment can significantly reduce seizure activity.
  • the five subjects in Cohort 1 had an average baseline seizure frequency of 32, 14, 26, 2, and 40 total seizures per month during the historical six-month baseline period, respectively, and have been followed for at least nine months after treatment.
  • these subjects had a median seizure reduction from baseline of 78% for all seizure events, including focal aware, focal impaired-awareness, and focal to bilateral tonic-clonic seizures (FIG. 41A-41B).
  • median seizure reduction from baseline was 82%, 82%, and 83%.
  • Subjects 102-001, 101-001, 115-001, 107-001, and 104-001 had a baseline average of 32, 2, 3, 2, and 10 disabling seizures per month, respectively.
  • Subjects 102-001 and 101-001 had a total seizure reduction from baseline of 97% and 99%, respectively, for all seizure types, with 97% and 100% total seizure reduction from baseline after month 13.
  • Subjects 102-001 and 101-001 reported disabling seizure reduction from baseline of 97% and 92%, respectively, with 97% and 100% reduction in disabling seizures after month 13.
  • Subject 102-001 has been free of focal impaired awareness seizures since the first month after treatment, and Subject 101-001 has been completely seizure-free since the seventh month after NRTX-1001 administration.
  • Subjects 102-001 and 101-001 have discontinued the immunosuppression regimen at approximately 12 months after NRTX1001 administration, as planned, and are reporting durable seizure reduction in the second year without any evidence of immunorejection or rebound in seizure frequency to date.
  • data obtained to date provide preliminary clinical evidence for significant seizure reduction in participants with drug-resistant MTLE (FIG. 41A-41B).
  • the preliminary clinical evidence emerging from Phase 1 of the ongoing NTE001 study suggests that NRTX-1001 reduced seizure activity without impairing cognition or triggering other serious adverse events. NRTX-1001 could effectively address a significant unmet need among patients with drug-resistant MTLE, a condition known for its debilitating impact on patients’ health.
  • AD Alzheimer’s disease
  • a ⁇ Abnormal amyloid ⁇ -protein
  • neural network activity is aberrantly increased in AD patients and animal models due to functional deficits in and decreased activity of GABA inhibitory interneurons, contributing to cognitive deficits.
  • AD patients and animal models are characterized by reduced ⁇ -oscillations. These brain rhythms underlie key short and long-term memory processes.
  • Targeting GABA inhibitory interneurons by transplantation may rescue cognitive impairment as well as alterations in neural activity seen in AD animals and patients.
  • Feasibility experiments were performed to accomplish 3 goals: (1) identification and validation of an appropriate AD mouse model by demonstration of abnormal EEG and cognitive defects, (2) demonstration of transplanted human pallial interneuron persistence in two AD mouse models, and (3) a human interneuron cell transplantation efficacy study.
  • 5XFAD and TG2576 two different transgenic AD models were identified, 5XFAD and TG2576, and their temporal deposition of amyloid plaques was validated, in which 5XFAD presented a fast accumulation in plaques (starting at 2-3 months of age) while TG2576 animals showed a slower progression (FIG. 42A-42B).
  • Neocortical focal epilepsy is a neurodevelopmental disorder that represents a major cause of refractory epilepsy. Currently, the only therapeutic option is surgical cortical resection, but only 30-50% of patients will achieve proper management of their seizures after surgery.
  • a mouse model of Tau aggregation (P301S and/or P301L) is used. Animals are administered hESC-derived interneurons of the present disclosure. After transplantation, pTau tangle pathology in the treated animals is evaluated. pTau tangle pathology is reduced in animals administered the hESC-derived interneurons compared to control animals that were administered vehicle.
  • Velmeshev D Perez Y, Yan Z, Valencia JE, Castaneda-Castellanos DR, Wang L, Schirmer L, Mayer S, Wick B, Wang S, Nowakowski TJ, Paredes M, Huang EJ, Kriegstein AR. Single-cell analysis of prenatal and postnatal human cortical development. Science. 2023 Oct 13;382(6667):eadf0834. doi: 10.1126/science.adf0834. Epub 2023 Oct 13. PMID: 37824647; PMCID: PMC11005279. 52. Fung SJ, Webster MJ, Sivagnanasundaram S, Duncan C, Elashoff M, Weickert CS.
  • actions such as “administering to the temporal lobe ipsilateral to the focal onset seizure a cellular composition” include “instructing the administration of a cellular composition to the temporal lobe ipsilateral to the focal onset seizure.”
  • features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.
  • the ranges disclosed herein also encompass any and all overlap, sub- ranges, and combinations thereof. Language such as “up to,” “at least,” “greater than,” “less than,” “between,” and the like includes the number recited.

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Abstract

Provided herein is a method of treating seizure activity by administering to a subject in need of treating seizure activity a therapeutically effective amount of a cellular composition that includes pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells. In some embodiments, at least 90% of the cells of the composition are post-mitotic cells. In some embodiments, at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1.

Description

NTHER.014WO PATENT METHODS OF TREATING SEIZURE ACTIVITY CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims priority to U.S. Provisional Application No. 63/587407, filed October 2, 2023, which is incorporated herein by reference in its entirety. BACKGROUND Field [0002] The present disclosure relates to pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells and methods of use thereof in a cell therapy to treat seizure activity and/or neuronal hyperexcitability. [0003] Mesial temporal lobe epilepsy (MTLE) is one of the most common types of focal epilepsy whereby seizures typically originate from a sclerotic hippocampus. Approximately one-third of people living with MTLE do not adequately respond to anti- seizure drugs and have few effective options. Surgery to remove or ablate the affected temporal lobe is one such option, but it is not indicated or effective for all and can result in adverse effects. SUMMARY [0004] Provided herein are methods of treating seizure activity, comprising: identifying a subject in need of treating seizure activity; and administering to the subject a therapeutically effective amount of a cellular composition comprising pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells. In some embodiments, 90% or more of the cells of the cellular composition are post-mitotic cells. In some embodiments, the cellular composition includes pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells, where at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1. In some embodiments, the cells of the cellular composition are substantially all pallial interneurons (e.g., are, are about, or are at least 90, 91, 92, 93, 94, 95, 96, 97, 98, 99%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 90-100%, 90-98%, 92-95%, 92-97%, etc.) pallial interneurons). In some embodiments, a frequency of seizures may be reduced after the administering, thereby treating the seizure activity. [0005] Also provided is use of a cellular composition for the treatment of seizure activity in a subject, the composition comprising pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells. In some embodiments, at least 90% of the cells of the composition are post-mitotic cells. In some embodiments, the cellular composition includes pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1. [0006] Also provided is a cellular composition comprising pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells, for the preparation of a medicament for treatment of seizure activity in a subject. In some embodiments, at least 90% of the cells of the cellular composition are post-mitotic cells. In some embodiments, the cellular composition includes, or are enriched for, pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1. [0007] Provided herein are therapeutic compositions of pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells. In some embodiments, at least 90% of the cells of the composition are post-mitotic cells. In some embodiments, the therapeutic composition includes pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1. In some embodiments, the composition may be used for the treatment of a focal onset seizure. [0008] Also provided herein are therapeutic compositions comprising: a poloxamer; and pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells at a concentration of about 1 x 105 cells/μL or greater. In some embodiments, the therapeutic composition includes pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells. [0009] Provided herein are methods of preparing a therapeutic composition for administering to a subject, comprising: providing pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells; and preparing a composition comprising: a poloxamer; and the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells at a concentration of about 1 x 105 cells/μL or greater. In some embodiments, the cellular composition includes pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells. [0010] In any method or composition herein, in some embodiments, a cellular composition of the present disclosure includes pluripotent stem cell-derived, subpallial, MGE-type GABAergic neuron cells, wherein at least 50% of the cells of the composition express LHX6, LHX8 or NKX2.1, and GAD1. In some embodiments, the composition is depleted for cells expressing ERBB4 or MAF/MAFB. In some embodiments, the subpallial, MGE-type GABAergic neuron cells include interneurons and/or projection neurons. [0011] Provided herein are delivery systems for transplanting cells into a tissue, comprising: a delivery cannula that includes: a proximal portion comprising a cellular liquid composition comprising cells at a concentration of about 1 x 105 cells/μL or greater; and a distal portion comprising a cell-free liquid chase vehicle, wherein the cellular liquid composition is stably held in the proximal portion by the liquid chase vehicle; and a displacement device connected to the distal end of the cannula and configured to cause the liquid chase vehicle to displace the cellular liquid composition to thereby expel the cellular liquid composition from the proximal end of the cannula. [0012] Also provided is a delivery system for transplanting cells into a tissue, comprising: a delivery cannula that includes a cellular liquid composition comprising cells at a concentration of about 1 x 105 cells/μL or greater; and a displacement device connected to a distal end of the cannula and configured to displace the cellular liquid composition in the cannula to thereby expel the cellular liquid composition from the proximal end of the cannula. BRIEF DESCRIPTION OF THE DRAWINGS [0013] FIGs. 1A and 1B are flow diagrams showing a method of treating a focal onset seizure, according to some non-limiting embodiments of the present disclosure. [0014] FIGs. 2A-2G show post thaw in vitro characterization of end-of-process cells derived from human embryonic stem cells (hESCs), according to some non-limiting embodiments of the present disclosure. FIG. 2A is a schematic diagram showing neuronal subtypes derived from the MGE progenitor domain. FIGs. 2B and 2C are a collection of images showing ICC staining of the hESC-derived cells with pallial MGE and cholinergic markers. FIG. 2D is a graph showing marker expression profile of the hESC-derived cells, according to some non-limiting embodiments of the present disclosure, as determined by immunocytochemistry (ICC) analysis. FIG. 2E is a graph showing GABA release from hESC-derived pallial MGE-type interneuron lots, undifferentiated hESCs and spinal motor neuron cultures. FIG. 2F is a graph showing acetylcholine release from hESC-derived pallial MGE-type interneuron lots, undifferentiated hESCs and spinal motor neuron cultures. FIG. 2G is a graph showing quantification of live cells in unsorted/sorted cell lots after cryopreservation and thaw. [0015] FIGs. 3A-3G show single cell RNA sequencing characterization of cell composition during in vitro differentiation, according to some non-limiting embodiments of the present disclosure. FIG. 3A is a plot showing UMAP (Uniform Manifold Approximation and Projection) visualization of cell clusters from samples combined. FIG. 3B is a collection of plots showing UMAP visualization of cell clusters from samples separately. FIG. 3C is a graph showing sample composition by cluster. FIG. 3D is a collection of plots visualizing gene expression across different clusters. FIG. 3E is a dot plot visualizing expression of key genes that define different cell categories. FIG. 3F is a dot plot showing projection of prediction scores between 0 and 1 onto day 14 and end-of-process clusters. FIG. 3G is a heatmap showing percentage of cells in each in vitro cluster that are assigned to different GE categories based on prediction scores. [0016] FIGs.4A-4W show electrophysiological characterization of grafted human interneurons in the rodent pallium, according to some non-limiting embodiments of the present disclosure. FIG. 4A is a collection of fluorescence microscopy images showing examples of grafted cell morphologies. FIG. 4B is a collection of fluorescence microscopy images showing expression of human- and pallial interneuron specific markers. FIG. 4C is a collection of fluorescence microscopy images showing HNA staining of recorded human cells in cortical slices. FIGs. 4D and 4E are electrophysiology traces showing action potential recorded from transplanted human interneurons. FIGS. 4F-4M are graphs showing physiological properties of grafted human cells. FIG. 4N is a collection of traces showing current recordings before and after treatment with NBQX. FIGs. 4O-4Q are graphs showing properties of glutamate–mediated spontaneous excitatory postsynaptic currents (sEPSCs) in transplanted human interneurons. FIGs. 4R and 4S are electrophysiology traces showing examples of human interneurons firing evoked APs. FIG. 4T is a collection of fluorescence microscopy images showing IHC staining of SYN-ChR2-YFP labeled human interneurons. FIGs. 4U-4W are graphs showing properties of sEPSCs in transplanted human interneurons. FIG. 4X is an electrophysiology trace showing recorded currents in light-stimulated ChR2- expressing human interneurons. FIG. 4Y is an electrophysiology trace showing recorded currents in endogenous mouse neurons after light stimulation of the human interneurons. FIG. 4Z is a graph showing the amplitude of light-evoked inhibitory postsynaptic currents in mouse neurons. [0017] FIGs. 5A-5H show an overview of the chronic MTLE mouse model and seizure suppression after cell transplantation. FIG. 5A is a schematic diagram showing the experimental timeline. FIGs. 5B and 5C are a collection of EEG traces at various time points post-transplant. FIG. 5D is a graph showing electrographic mesiotemporal seizure frequency for epileptic animals treated with hESC-derived interneurons. FIG. 5E is a graph showing cumulative duration of seizures for epileptic animals treated with hESC-derived interneurons. FIG. 5F is a graph showing electrographic mesiotemporal seizure frequency for epileptic animals treated with hESC-derived interneurons. FIG. 5G is a fluorescence microscopy image showing staining of the hippocampus for markers for human cells and interneurons. FIG. 5H is a fluorescence microscopy image showing staining of the hippocampus for markers for human cells and neurons. [0018] FIGS. 6A-6G show histological characterization of interneuron in the epileptic hippocampus. FIG. 6A is a collection of fluorescence microscopy images showing staining for markers of immature neurons and human cells. FIG. 6B is a collection of fluorescence microscopy images showing staining for markers of MGE interneurons and human cells. FIG. 6C is a collection of fluorescence microscopy images showing staining for a human-specific neuronal marker. FIG. 6D is a collection of fluorescence microscopy images showing staining for a human housekeeping gene and GABAergic neuronal marker. FIG. 6E is a collection of fluorescence microscopy images showing staining for human cells, MGE interneuron markers, and a perineuronal net marker, as well as lack of expression of off-target markers. FIG. 6F is a graph showing the rate of persistence of human cells. FIG. 6G is graph showing marker expression in persisting human cells. [0019] FIGs. 7A-7J show human interneuron dose-response activity in the MTLE model, according to some non-limiting embodiments of the present disclosure. FIG. 7A is a graph showing seizure frequency in epileptic animals treated with different doses of hESC- derived MGE-type pallial interneurons, according to some non-limiting embodiments of the present disclosure. FIG. 7B is a collection of images showing immunohistochemical staining of the hippocampus for HNA and DAPI. FIG. 7C is a collection of images showing immunohistochemical staining of the hippocampus for HNA and LHX6. FIG. 7D is a collection of images showing immunohistochemical staining of the hippocampus for HNA and SST. FIGs. 7E-7J show quantification of human cell persistence and fate. FIGs. 7E and 7H are graphs showing, respectively, the total number of persisting human cells at 8.5 MPT and rate of persistence as a percentage of the initial dose. FIGs. 7F and 7I are graphs showing quantification of the total number of LHX6 positive human cells and the percentage of human cells expressing LHX6, respectively. FIGs. 7G and 7J are graphs showing the total number of SST positive human cells and the percentage human cells expressing SST, respectively. [0020] FIGs. 8A-8Q show epileptic hippocampal pathology, behavioral outcome and animal survival after human interneuron transplantation, according to some non-limiting embodiments of the present disclosure. FIG. 8A is an image showing DAPI labeling of the granule cell (GC) layer in a naïve animal. FIG. 8B is an image showing DAPI labeling of the GC layer in an epileptic animal treated with vehicle. FIGs. 8C, 8D, 8E, and 8F are each an image showing DAPI labeling of the GC layer in an epileptic animal treated with the indicated dose of hESC-derived interneurons (per hippocampus). FIGs. 8G and 8H are graphs showing measurements of the GCL width and area, respectively. FIGs. 8I and 8J are images showing immunohistochemical staining of the hippocampus for caspase3 with NEUN and HNA. FIGs. 8K and 8L are images showing immunohistochemical staining of the hippocampus for calbindin and HNA. FIG. 8M is a collection of bar graphs showing results of a modified Irwin screen. FIG. 8N is a collection of bar graphs showing open field test results. FIG. 8O is a bar graph showing Y maze results. FIG. 8P is a bar graph showing Barnes Maze results. FIG. 8Q is survival curve for epileptic animals treated with either vehicle, or transplanted with cells. [0021] FIGs. 9A-9G show in vitro characterization of hESC-derived VZ-like MGE progenitors after the two-week patterning phase, according to some non-limiting embodiments of the present disclosure. FIG. 9A is a collection of images showing FOXG1 expression in hESC-derived MGE-like progenitors by ICC (middle and bottom panels) and in the developing mouse brain at E13.5 by in situ hybridization (top panel). FIG. 9B is a collection of images showing NKX2-1 expression in hESC-derived MGE-like progenitors by ICC (middle and bottom panels) and in the developing mouse brain at E13.5 by in situ hybridization (top panel). FIG. 9C is a collection of images showing OTX-2 expression in hESC-derived MGE-like progenitors by ICC (middle and bottom panels) and in the developing mouse brain at E13.5 by in situ hybridization (top panel). FIG. 9D is a collection of images showing LHX6 staining in hESC-derived MGE-like progenitors by ICC (bottom panel) and in the developing mouse brain at E13.5 by in situ hybridization (top panel). FIG. 9E is a collection of images showing PAX6 staining in hESC-derived MGE-like progenitors by ICC (bottom panel) and in the developing mouse brain at E13.5 by in situ hybridization (top panel). FIG. 9F is a collection of images showing NKX2-2 staining in hESC-derived MGE-like progenitors by ICC (bottom panel) and in the developing mouse brain at E13.5 by in situ hybridization (top panel). FIG. 9G is a graph quantifying expression of different markers in hESC-derived MGE-like progenitors across different lots. FIG. 9H is a graph quantifying expression of different markers in hESC-derived MGE-like progenitors in lots 1 and 2. [0022] FIGs. 10A-10J show efficient and reproducible hESC differentiation into MGE-type pallial interneurons, according to some non-limiting embodiments of the present disclosure. FIG. 10A is a schematic showing MGE pallial-type interneuron differentiation from hESCs and key markers used to characterize each stage. FIG. 10B is a collection of images showing expression of the indicated markers by ICC at different time points. FIG. 10C is a graph quantifying expression of the indicated markers over the different time points. FIG. 10D is a collection of images showing expression of the indicated markers by ICC at different time points. FIG. 10E is a graph quantifying expression of the indicated markers over the different time points. FIG. 10F is a collection of images showing expression of the indicated markers by ICC at different time points. FIG. 10G is a graph quantifying expression of the indicated markers over the different time points. FIG. 10H is a graph showing the percentage of cells staining positive for the indicated markers, with or without MEK pathway inhibition. FIGs. 10I and 10J are a collection of images showing LHX8 expression in end-of-process pallial interneuron, with or without MEK pathway inhibition. [0023] FIGs. 11A-11E show that no residual proliferative progenitors or pluripotent stem cells were identified in the end-of-process (week 6) samples, according to some non-limiting embodiments of the present disclosure. FIG. 11A is a graph quantifying Ki67 staining of cells derived from hESC with or without NOTCH and CDK pathway inhibition. FIG. 11B is a graph quantifying 5-ethynyl-2’-deoxyuridine (EdU) staining of cells derived from hESC with or without NOTCH and CDK pathway inhibition. FIG. 11C is a collection of images showing Edu staining in cells derived from hESC with (bottom panels) or without (top panels) NOTCH and CDK pathway inhibition. FIG. 11D is a collection of images showing Ki67 staining in cells derived from hESC with or without NOTCH and CDK pathway inhibition. FIGs. 11E and 11F are graphs quantifying expression of the indicated markers in cells derived from hESC with or without NOTCH and CDK pathway inhibition. FIGs. 11G-11I are a collection of flow cytometry plots showing distribution of cells expressing the indicated pluripotency markers for in-process (Week 4, FIG. 11G) and end-of- process (FIG. 11H) samples. FIG. 11I is a table showing the limits of detection (LOD) for residual TRA-1-60+/OCT4+ cells for in-process and end-of-process samples. [0024] FIGs. 12A-12E show in vitro migration phenotypes of hESC-derived pallial MGE-type interneurons, according to some non-limiting embodiments of the present disclosure, compared to human endogenous MGE interneurons and commercially available hPSC-derived GABAergic cells. FIG. 12A is a collection of phase contrast images showing a cell aggregate before (left most panel) and after 3 days of migration (remaining panels). FIG. 12B is a collection of images showing staining for LHX6, MAFB, and ERBB4 by immunocytochemistry (ICC). FIG. 12C is a graph quantifying percent migrating cells after 3 days. FIG. 12D is a collection of images comparing marker expression in hESC-derived pallial GABAergic MGE-type interneurons, according to some non-limiting embodiments of the present disclosure, and two commercial sources of hPSC-derived GABAergic neurons. FIG. 12E is a table comparing qualitative analysis of marker expression in pallial GABAergic interneurons derived from hESC, according to some non-limiting embodiments of the present disclosure, and two commercial sources of hPSC-derived GABAergic neurons. [0025] FIGs. 13A-13C show single cell RNA sequencing gene expression patterns in vitro and in the developing human GE. FIG. 13A is a dot plot showing expression level of genes in each cluster. FIGs. 13B and 13C are a collection of violin plots showing expression of genes associated with different cell stages and cell types, by sample (FIG. 13B) and by cluster (FIG. 13C). FIG. 13D is plot visualizing gene expression across clusters. [0026] FIGs. 14A-14H show reproducible seizure suppression achieved with additional independent cell production lots. FIG. 14A is an image showing the right hippocampus and the kainate injection site (CA1). FIG. 14B is a collection of images showing the right hippocampus overlayed with the sites of administration of the hESC- derived interneurons (dots) and the site of depth electrode implantation (arrow). FIG. 14C is a graph showing seizure frequency based on EEG recordings made at the indicated time points. FIG. 14D and 14E are graphs showing seizure frequency and cumulative seizure duration based on EEG recordings made at the indicated time points. FIG. 14F is a collection of images showing expression of SST and HNA in transplanted human cells. FIG. 14G is a collection of images showing fluorescence in situ hybridization (FISH) staining of the distribution of transplanted human cells in the hippocampus. FIG. 14H is a collection of images showing immunohistochemistry staining of transplanted human cells in the hippocampus. [0027] FIG. 15 is a collection of graphs showing stability of cryopreserved hPSC- derived, pallial, MGE-type GABAergic interneurons after thawing. [0028] FIGs. 16A and 16B are collection of graphs showing consistent delivery of hPSC-derived, pallial, MGE-type GABAergic interneurons held in a cannula configured to hold and deliver the cells, according to some non-limiting embodiments of the present disclosure. [0029] FIG. 17 is a collection of schematics and plots showing stability of cells post-thaw and after a hold period in a cannula, according to some non-limiting embodiments of the present disclosure. [0030] FIG. 18 is a collection of images showing migration potential of cells post-thaw and after a hold period in a cannula, according to some non-limiting embodiments of the present disclosure. [0031] FIGs. 19A-19I show molecular characterization of human pallial interneurons 1-18 months post transplantation (MPT) using single nuclei RNA sequencing (snRNAseq). FIG. 19A is a plot showing UMAP (Uniform Manifold Approximation and Projection) visualization of cell clusters. FIG. 19B is a collection of plots showing prediction scores of transplanted hESC-derived pallial interneuron (pIN) gene expression compared with endogenous human pINs from adult M1 cortex. FIG. 19C is a collection of dot plots showing expression level of key genes that define different cell categories by the transplanted hESC-derived pINs. FIGs. 19D-19F are a collection of plots showing expression level of different genes across cells among the transplanted hESC-derived pINs. FIG. 19G is a plot showing subclass categories of transplanted human cells based on prediction and cluster marker analyses. FIG. 19H is a graph showing quantification of graft composition by subclass categories across 5 time points post-transplant. FIG. 19I is plot showing projection of hESC-derived MGE pIN subclasses onto human prenatal-adult prefrontal cortex interneuron dataset. [0032] FIG. 20 is a collection of graphs showing the effect of single-dose administration of NRTX-1001 in subjects with drug-resistant MTLE, according to some non- limiting embodiments of the present disclosure. [0033] FIG. 21 is a collection of graphs showing levels of metabolites in the hippocampus of a subject treated with NRTX-1001, according to some non-limiting embodiments of the present disclosure. [0034] FIG. 22 depicts data showing the results of neurocognitive tests in subjects treated with NRTX-1001, according to some non-limiting embodiments of the present disclosure. [0035] FIG. 23A is a collection of graphs showing the effect of transplanting hESC-derived interneurons on urethane-induced theta oscillations in a 5xFAD Alzheimer’s disease model. [0036] FIG. 23B is a collection of graphs showing the effect of transplanting hESC-derived interneurons on 5xFAD AD mice treated with riluzole. [0037] FIG. 24 is a schematic diagram showing a cell delivery system and use thereof, according to some non-limiting embodiments of the present disclosure. [0038] FIGs. 25A-25N shows stable graft composition from 1 to 18 MPT comprised of PVALB and SST subclasses, according to some non-limiting embodiments of the present disclosure. FIG. 25A shows the experimental design: Cell lots (N=5) were transplanted into the neonate cortex in 3 deposits per hemisphere (75,000 cells/deposit). Cortical tissues (region of interest, ROI) were dissected at 1 MPT (N=3 lots), 3-4 MPT (N=3 lots), 6-7 MPT (N=4 lots), 12 MPT (N=2 lots) and 18 MPT (N=2 lots). Tissues from 2-3 animals were dissected for each lot and each time point and pooled for nuclei isolation. Nuclei were stained with an antibody against human nuclear antigen (HNA), followed by fluorescence activated nuclear sorting (FANS) to enrich rare human cells. The entire sorted samples were captured on microfluidic chips using the 10X controller (10X Genomics), followed by cDNA and library preparation for sequencing. Cells were aligned to both human and mouse transcriptomes, filtering out any captured mouse nuclei from downstream analyses. FIG. 25B shows integrated UMAP clustering of all the human cells across time points. FIG. 25C shows feature plots of GABAergic (GAD1, GAD2) and MGE (LHX6, SOX6) markers. FIG. 25D shows expression by cluster of genes that characterize different cell categories, including general markers of neurons, GABAergic and MGE neurons, preoptic area (POA), caudal and lateral GE (CGE/LGE), neuronal progenitors (NPC), cycling cells, ESC, as well as genes associated with glial cells, glutamatergic neurons (Glu), dopaminergic neurons (DA), serotonergic neurons (5HT) and cholinergic neurons (Ach). FIG. 25E shows population prediction scores comparing transplanted cells with human adult brain superclusters corresponding to diverse cell types 42. FIG. 25F shows MGE interneuron prediction scores overlaid onto grafted cell UMAP. FIG. 25G shows graft composition over time based on transcriptional similarity to adult brain superclusters. FIG. 25H shows MGE- and CGE-derived interneuron subclass prediction scores overlaid onto grafted cell UMAP. For reference, the middle temporal gyrus (MTG) interneuron dataset was used 48. FIG. 25I shows expression of markers associated with pIN subclasses listed at the top of each column. FIG. 25J shows UMAP visualization of the interneuron subclasses identified in the transplanted cells based on clustering and prediction analyses. FIGs. 25K and 25L show graft composition by subclass over time. FIG. 25M shows repeated measurements of a single lot composition transplanted from five different vials (n=5 technical replicates) at 1 and 4 MPT. FIG. 25N shows expression of subclass-enriched genes. For FIGs. 25G, 25K, 25L, data shown are mean ± SEM. [0039] FIGs. 26A-26L show additional characterization of post-transplant cell identity. FIG. 26A shows quality metrics of post-transplant cell clusters, including number of unique genes detected (nFeature), number of total RNA molecules (nCount), percentage of mitochondrial and ribosomal genes, according to some non-limiting embodiments of the present disclosure. FIGs. 26B and 26C show UMAP colored by Age (FIG. 26B) and by batch ID (FIG. 26C). FIG. 26D shows expression of key genes over time. FIGs. 26E and 26F show prediction scores projected onto the integrated UMAPs based on comparisons to the listed human adult brain cell types (FIG. 26E) and brain regions (FIG. 26F) 42. The ridge plot on the right panel in FIG. 26F shows distribution of prediction scores for the transplanted population compared to each reference brain region. FIG. 26G shows prediction scores projected onto the integrated UMAPs based on comparisons to endogenous human PVALB, SST and SST NPY subclasses, separated by age. The ridge plots show distribution of prediction scores for each subclass over time compared to adult human MTG (middle panels) 48 and M1 cortex (right panels) 49 reference datasets. FIG. 26H shows expression of several conserved markers (ERBB4, SLIT2, SHISA9, RUNX2) enriched in endogenous PVALB INs compared to SST INs in the adult human M1 cortex and mouse cortex + hippocampus (adapted from the Allen Brain Map: Cell Types Database). FIGs. 26I-26L show grafted human cells analyzed by fluorescence in situ hybridization (FISH) using RNAscope probes against the GABAergic marker glutamate decarboxylase 1 (GAD1), PVALB-enriched marker SLIT2, SST and NPY to assess the main cell populations. FIG. 26I shows MALAT1 was chosen as a FISH probe target to identify all human cells due to its strong and ubiquitous expression, regardless of subclass or MPT (99.99% of the cells are positive). FIG. 26J shows expression of GAD1, SLIT2, SST, and NPY transcripts by subclass over time. FIG. 26K shows representative FISH images showing expression of listed targets in transplanted human cells in the mouse cortex. Note that the GAD1 probe, although designed against human mRNA sequence, also binds to endogenous mouse GAD1. FIG. 26L shows quantification of MALAT1+ cells co-expressing listed targets. Each dot is from a different hemisphere, after averaging technical replicates (4 sections each). 1 MPT (n=3 hemi, 2 cell lots), 4-18 MPT (n=8 hemi, 3 cell lots). Lines show mean ± SEM. [0040] FIGs. 27A-27J show transplantation environment triggers expression of synaptic genes enabling rapid cell fate identification, according to some non-limiting embodiments of the present disclosure. FIGs. 27A, and 27B show integrated clustering analysis of one lot (010519S1) sequenced prior to transplantation (whole cells = PRE cell, and nuclei = PRE nuc), after one month of in vitro (30 DIV), 14 days post-transplantation (14 DPT) and 1 MPT, colored by cluster (FIG. 27A) and by subclass (FIG. 27B). FIG. 27C shows alluvial plots showing transcriptomic relationship between pre- and post-transplant cell populations. FIG. 27D shows graft composition by subclass at 14 DPT and 1 MPT. FIGs. 27E and 27F show PVALB, SST and SST NPY prediction scores across samples shown as feature plots (FIG. 27E) and ridge plots (FIG. 27F). FIG. 27G shows expression of cell-type- specific genes upregulated in 1 MPT vs 30 DIV samples. FIGs. 27H-27J show evaluation of graft development post-transplantation compared with human cortical development spanning from prenatal to postnatal stages. The quantification is based on predicted cell stage analysis using cortical developmental datasets as a reference 51. FIG. 27H shows distribution of grafted cell maturation states over time on the top relative to broad human stages, corresponding to developmental changes in neuronal physiology shown on the bottom (adapted from 19). FIG. 27I shows grafted cell maturation states over time separated by the three main subclasses. FIG. 27J shows on the left, the re-clustering of endogenous human interneurons from prefrontal cortex, PFC (original dataset from 51) colored by age, with the CGE- and MGE-derived interneuron populations indicated. On the right, projection of grafted cells at different stages colored by subclass onto human PFC interneurons. [0041] FIGs. 28A-28G show gene expression patterns under different conditions and at different stages post-transplant. FIGs. 28A and 28B show integrated clustering analysis of lot 010519S1 sequenced prior to transplantation (PRE cells and PRE nuclei), after 30 DIV (nuclei), 14 DPT (nuclei) and 1 MPT (nuclei), colored by cluster (FIG. 28A) and by subclass (FIG. 28B). FIG. 28C shows expression of ERBB4 (enriched in PVALB subclass) and RELN (enriched in SST subclass) in PRE, 30 DIV and 1 MPT nuclei samples. FIG. 28D shows GO term analysis for biological processes enriched in subclass-specific genes that are upregulated in 1 MPT vs 30 DIV samples. FIGs. 28E-28G show GO term analysis for biological processes (FIG. 28E), cellular components (FIG. 28F), and molecular functions (FIG. 28G) enriched at each of the main transcriptional states: PRE, 1 MPT, and 3+ MPT. [0042] FIGs. 29A-29L show cell development is characterized by major transcriptional changes during the first 3 MPT followed by gradual unfolding of gene modules involved in regulation of synaptic transmission and membrane potential. FIGs. 29A- 29C show clustering analysis of all the cells pooled together (without integration), colored by MPT (FIG. 29A), by subclass with all the stages combined (FIG. 29B), or separated by MPT (FIG. 29C). FIG. 29D shows expression of neuronal, GABAergic and MGE markers across transcriptional states. FIG. 29E shows stage-specific expression pattern corresponding to pre- transplant (PRE), 1 MPT and 3-18 MPT transcriptional states. FIG. 29F shows gene networks of top 4 GO biological processes enriched at each of the main transcriptional states. FIG. 29G shows identification of genes through DGE analysis that continue to be upregulated over time. FIG. 29H shows GO term analysis for biological processes that are enriched after 3 MPT and 6 MPT. FIGs. 29I and 29J show expression of gene modules that regulate chemical synaptic transmission (FIG. 29I) and membrane potential (FIG. 29J) in the grafts over time (top plots). In the bottom plots, expression of the same modules is plotted for 18 MPT grafts in the context of human cortical development. FIGs. 29K and 29L show expression of genes identified in continuously upregulated modules involved in vesicle- mediated transport in synapse, modulation of chemical synaptic transmission and synapse organization (FIG. 29K), as well as regulation of presynaptic membrane and action potential (FIG. 29L). [0043] FIGs. 30A-30G show hMGE-pIN grafts are comprised of multiple PVALB and SST subtypes, according to some non-limiting embodiments of the present disclosure. FIG. 30A shows the cluster correlation to each other. FIG. 30B shows the proportion of nuclei from the 18 MPT ESC-derived clusters (columns) that correspond to endogenous adult interneuron subtypes (rows) defined in the cell census atlas of the mammalian primary motor cortex 10 based on prediction analysis. Of the 72 transcriptionally defined CGE- and MGE-derived interneuron subtypes, only the ones which transplanted hMGE-pINs match by >10% are included in this heatmap. To the right, human cluster cellular taxonomy classification is shown, based on mouse/human cross-species overlap analysis, where multimodal data (morphology, physiology and transcriptomics) were applied to define the mouse interneuron subtypes 10. FIG. 30C shows UMAP of all the transplanted cells, colored by transcriptionally distinct populations based on data-driven marker analyses, cluster correlations and overlap with human interneuron subtypes. FIG. 30D shows graft composition by subtype over time. Bar graphs shown mean ± SEM. FIG. 30E shows top subtype markers. FIG. 30F shows expression of transcription factors, sodium, calcium and potassium voltage gated ion channels and regulatory subunits, as well as cell adhesion molecules involved in cell recognition 43, in pooled 12-18 MPT data across subtypes. FIG. 30G shows expression of several voltage gated ion channels over time and across subtypes. [0044] FIGs. 31A-31S shows grafted hMGE-pINs acquire histological features of known PVALB and SST subtypes, according to some non-limiting embodiments of the present disclosure. FIG. 31A shows a diagram showing transplantation sites and dosing in the neonatal cortex for histological characterization. FIG. 31B shows distribution of hMGE-pINs labeled with human-specific nuclear antigen (HNA), the immature neuronal marker DCX, and the MGE-lineage marker LHX6 at 1 MPT (coronal view). FIG. 31C shows the percent of HNA+ cells persisting at 1, 4, and 17 MPT out of the number of cells that were injected. FIG. 31D shows the relative rostrocaudal distribution of HNA+ cells at 1 and 4 MPT. FIG. 31E shows the relative positioning of hMGE-pINs in the cortex based on expression of ERBB4 / SST (upper panel, n=199 cells from 3 transplanted animals; 22.6% ERBB4+, 41.2% SST+) and SST / NOS1 (lower panel, n=396 cells from 3 transplanted animals; 49.4% SST+, 9.6% NOS1+). Dashed lines indicate the surface, layers I/II, III/IV, and V/VI transitions (from top to bottom). FIG. 31F shows an example of hMGE-pIN with Martinotti morphology. Martinotti cells are characterized by mid-to-low SST and CNTNAP4 expression and long ascending axon collaterals that reach layer I to profusely ramify. FIGs. 31G and 31H show human SST-positive cells co-expressing Martinotti markers CALB1 (FIG. 31G) and ETV1 (FIG. 31H). FIG. 31I and 31J show human SST-positive cells co-expressing SST1 (predicted non-Martinotti subtype) cluster markers GULP1 (FIG. 31I) and NPAS3 (FIG. 31J). FIG. 31K shows an example of a GFP-labeled long-range projection (LRP) neuron in layer VI with a long axonal collateral projecting parallel to the corpus callosum (inset shows SST+ expression in its soma and higher magnifications of the long projection). FIGs. 31L and 31M show human cells with LRP characteristics frequently express SST, NPY, and NOS1. FIG. 31N-31P show representative images of NPY+SST+ axonal projections, which are frequently found in the caudal hippocampus (medial DG-CA3 (FIG. 31N)), midline corpus callosum (FIG. 31O), and caudate putamen (next to the nucleus accumbens (FIG. 31P)). FIG. 31Q shows an example of a ERBB4+ (SST negative) hIN with basket cell features in layer IV. FIG. 31R shows these cells form axonal arborizations (marked by human-specific SYP) around the somata of pyramidal neurons and interneurons. FIG. 31S shows nuclear expression of the PV2 (predicted Basket subtype) cluster marker BCL6. Inset shows BCL6 nuclear expression and lack of SST expression. All images and quantifications were taken from animals at 7-15 MPT. [0045] FIGs. 32A-32N’ show hMGE-pINs exhibit subclass-specific synaptic connectivity features in the host mouse cortex, according to some non-limiting embodiments of the present disclosure. FIGs. 32A-32B show increased cortical expression of the human- specific synaptophysin (SYP) in layers I-II (FIG. 32A) and IV (FIG. 32B) at 1, 7, and 13 MPT. FIG. 32C show Diagram showing a pyramidal projection neuron with dendritic (Pex5L) and somatic (NeuN), as well as presynaptic (Gephyrin and GabaR1) marker expression. Postsynaptic and axonal markers associated with SST (green) and PVALB (red) subclasses are illustrated collocalizing with human-specific TAU and SYP. FIG. 32D and 32E show examples of inhibitory synapses found in layer I composed of presynaptic human SYP and SST and postsynaptic Gephyrin (arrows). FIG. 32F shows SST-expressing human axonal terminals are intimately intertwined with Pex5L+ distal dendrites of pyramidal cells (FIG. 32F’, 32F” show higher magnifications with SST expression). FIG. 32G, 32G’ show representative images showing co-expression of human-specific SYP and synaptoporin (SYPR) in axonal terminals in layers I/II. FIGs. 32H and 32I show examples of human axonal processes in layer I co-expressing SST, the glutamate ionotropic receptor, GRIN3A (FIG. 32H), and the SST1-cluster marker, ARHGAP6 (arrows in 32I; additional examples are shown in 32I’ and I”). FIGs. 32J-32L show Human axonal terminals show perisomatic synaptic patterns associated with PVALB cells in layer IV. Examples of perisomatic synapses formed between presynaptic human SYP (FIG. 32J, 32K) and LGI2 (FIG. 32L), and host cell postsynaptic GabaR1 (arrows). Bottom panels (FIGs. 32J’-32L”) correspond to additional examples for each marker combination at higher magnification. NeuN labels neuronal cell bodies (FIG. 32K). FIG. 32M and 32N show representative images showing perisomatic human axonal terminals co-expressing the PVALB-enriched potassium channels, KIR3.1 (encoded by KCNJ3) and KV3.2 (encoded by KCNC2) (FIG. 32M and 32N, respectively). Insets (32M’ and 32N’) correspond to higher magnification of their respective images. Samples were obtained at 7-18 MPT. [0046] FIGs. 33A-33D show stability of cells post-thaw and following a hold period in a cannula, according to some non-limiting embodiments of the present disclosure. The data demonstrate that the viability (FIG. 33A), concentration (FIG. 33B), metabolic activity (FIG. 33C), and migratory potential (FIG. 33D) of cells held for 48 hours at 2-18°C are comparable to the overnight hold reference control after 7 hours of cannula retention at room temperature. The study includes N = 5-10 independent experiments using 6 different cell batches. Error bars represent the standard error of the mean. [0047] FIGs. 34A-34C show persistence, migration, and distribution of hPSC- derived GABAergic interneurons at 1 month-post-transplantation (1 MPT) into neonate P1-2 rodent brains, according to some non-limiting embodiments of the present disclosure. Results show that cell persistence (FIG. 34A), migration (FIG. 34B) and distribution of cells (FIG. 34C) following hypothermic storage at 2-18C for 48-72 hrs are comparable to the overnight reference control dose preparation method. [0048] FIGs. 35A-35B show single-cell RNA sequencing analysis of hPSC- derived GABAergic interneurons after 1 month and 4 months post-transplantation, according to some non-limiting embodiments of the present disclosure. Transplantation into rodent brains revealed no off-target cell types, off-target gene expression, or significant differences in gene expression patterns (FIG. 35A). The gene expression profiles and composition were consistent between cells stored at 2-18°C for 48-72 hours and the overnight reference control, and were comparable between the 1-month and 4-month post-transplantation time points (FIG. 35B). [0049] FIGs. 36A-36B show effects of neurotransmitter receptor antagonists on spontaneous calcium activity from in vitro human pallial interneuron (hpIN) cultures, according to some non-limiting embodiments of the present disclosure. FIG. 36A shows calcium traces show activity of 30 neurons before (baseline) and after the addition of small molecule antagonists (dashed red line). After 17 days in vitro, samples were treated using control media (vehicle), two sets of two compounds (Picrotoxin + Saclofen or NBQX + AP- 5), or TTX, all diluted in vehicle media. FIG. 36B shows fold change in firing rate after application of each set of compounds shows no significant changes in calcium activity before and after addition of vehicle (control media), picrotoxin and saclofen (GABAA and GABAB receptor antagonists, respectively), or NBQX and AP-5 (AMPA- and NMDA-receptor antagonists, respectively). However, the addition of TTX (Na+ channel blocker) almost completely abolished calcium activity, indicating that the calcium activity is mediated by action potentials. Statistics: One way ANOVA with Bonferroni post-hoc analysis (ns-no significance, *p<0.05, **p<0.01, ***p<0.001). [0050] FIGs. 37A-37T show multi-electrode array analysis of co-cultured hiPSC derived glutamatergic neurons, mouse primary astrocytes with or without human GABAergic pallial interneurons (hpIN) , according to some non-limiting embodiments of the present disclosure. FIG. 37A shows representative immunostaining images demonstrating survival of glutamatergic neurons (EMX2, TBR1), astrocytes (GFAP) and interneurons (LHX6, SST) after 40 days of co-culture in vitro on the MEA plate (FIGs. 37B-37C). Analysis of synchrony index and mean firing rate for Cell Dynamics Incorporated (CDI) iPSC-derived glutamatergic neurons with only primary mouse astrocytes (blue, CDI Gluta alone) or with human pallial interneurons (green, CDI Gluta + hpIN). FIGs. 37D-37E shows analysis of synchrony index and mean firing rate for Bit.bio (ioGluta) iPSC-derived glutamatergic neurons with only primary mouse astrocytes (purple, BitBio Gluta alone) or with human pallial interneurons (red, BitBio Gluta + hpIN). FIG. 37F-37K show connectivity (synchronicity) and neuron network dynamics (network) measurements for 24 days in vitro (DIV) (highlighted dashed box in FIGs. 37D-37E) show a clear difference +/- hpIN. FIG. 37L shows ioGluta only cultures show no changes in neural acivity after the addition of the GABAA receptor antagonist, picrotoxin. However, ioGluta + hpIN show an obvious change in network activity after the addition of picrotoxin. FIG. 37M shows PCA analysis revealing that ioGluta-only cultures cluster together before and after picrotoxin addition, while ioGluta + hpIN cultures cluster separately at baseline but move closer to ioGluta-only wells, post- picrotoxin treatment. FIG. 37N-37Q show UMAP analysis of all network events detected at DIV 40 in the MEA system across 4 samples (n=6 wells per sample): (FIG. 37N) ioGluta alone at baseline, (FIG. 37O) ioGluta alone post 20 minutes treatment with picrotoxin, (FIG. 37P) ioGluta co-cultured with hpIN at baseline and (FIG. 37Q) ioGluat+hpIN after a 20 minutes picrotoxin treatment. FIG. 37R shows Louvain clustering analysis identified 6 main clusters in the UMAP representation of all network event properties. FIG. 37S shows a specific color has been attributed to each cluster. FIG. 37T shows quantification of network event distribution across the 6 identified clusters demonstrate ioGluta alone cultures show similar distribution of the network events before and after picrotoxin addition. However, ioGluta + hpIN clustering shows a very different distribution with a large portion of network events in cluster#2 not shared with ioGluta alone cultures. The addition of picrotoxin to ioGluta + hpIN leads to a distribution of network events in these clusters that resembles ioGluta alone before and after picrotoxin. Acronyms: CC – Cross-correlegram, NB – network burst, NBpC – network burst per electrode. [0051] FIGs. 38A-38B shows epileptic MTLE mouse model behavioral outcome after human pIN transplantation, according to some non-limiting embodiments of the present disclosure. (Open Field test (FIG. 38A, general anxiety, spatial locomotion and travel velocity) and Light-Dark Emergence (FIG. 38B, Anxiety). Also shown are percent of animals emerged and non-emerged. Data are shown for the middle dose (200K). Kruskal Wallis test for differences between groups; significant differences are indicated by asterisk (P<0.05). [0052] FIGs. 39A-39E show an epileptic MTLE mouse model hippocampal pathology analysis showing that the progression of dentate granule cell dispersion from before transplant to 8.5 months post-human pIN transplantation is halted, with similar dispersion observed across time points post-transplant, according to some non-limiting embodiments of the present disclosure. FIG. 39A shows granule cell dispersion analysis at 1 MPSE (age and time-matched to efficacy study mice at time of pIN transplantation. FIGs. 39A-39D show granule cell dispersion analysis at 8.5 MPT in age-matched mice: Prox1 labeling shows representative granule cell (GC) layer in early epileptic mice (FIG. 39A), naive mouse age-matched to end of study mice (FIG. 39B), epileptic cell-treated mice at end of study (FIG. 39C) and epileptic vehicle-treated mice at end of study (FIG. 39D). FIG. 39E shows Average GC layer area. All data are mean ± SEM. The Kruskal Wallis statistic, followed by Dunn’s test, was significant between all three groups at the end of the study (P<0.05). GC area in epileptic mice at time of transplant was not significantly different from cell-treated mice at the end of study. [0053] FIGs. 40A-40D show percent change from baseline in neurocognitive and quality of life test performance after low dose administration of NRTX-1001 to human MTLE subjects in the ongoing Phase 1/2 study, according to some non-limiting embodiments of the present disclosure. FIG. 40A shows BNT = Boston Naming Test total score. FIG. 40B shows BVMT: Brief Visuospatial Memory Test delayed recall score. FIG. 40C shows RAVLT: Ray Auditory Verbal Learning Test delayed recall score. FIG. 40D shows QOLIE- 31P: Quality of Life total score. T-score measurements with reliable change index noted. [0054] FIGs. 41A-41B show percent change from baseline in monthly seizure frequency after low dose administration of NRTX-1001 to human MTLE subjects in the ongoing Phase 1/2 study, according to some non-limiting embodiments of the present disclosure. FIG. 41A shows all seizures plotted, including focal aware, impaired awareness, and focal to bilateral tonic clonic seizures. FIG. 41B shows only disabling seizures plotted, including focal aware, impaired awareness, and focal to bilateral tonic clonic seizures as above but excluding aware seizures without objective manifestation (auras). [0055] FIGs. 42A-42B show histological characterization of amyloid plaques in two Alzheimer’s disease (AD) mouse models: 5XFAD and TG2576, according to some non- limiting embodiments of the present disclosure. FIG. 41A shows amyloid plaque deposits are observed in the cortex and hippocampus in two models of AD, TG2576 and 5XFAD at 21 and 16 months of age. FIG. 41B shows higher magnification images of the amyloid plaques (cyan) surrounded by activated microglia marked by CD68 (red) in the TG2576 and 5XFAD models. [0056] FIGs. 43A-43B show human interneuron transplantation in two mouse models of Alzheimer’s disease, according to some non-limiting embodiments of the present disclosure. FIG. 43A shows images of human ESC-derived interneurons transplanted into the rostro-dorsal and caudal-ventral hippocampus of 5XFAD mice at 11 MPT. The transplanted cells (marked by human-specific nuclear antigen (HNA) and the interneuron subtype marker, SST) persist and migrate throughout the hippocampus. In addition, the transplanted cells project extensively to surrounding areas as marked by the human-synaptophysin (SYP) marker. FIG. 43B shows images of human ESC-derived interneurons transplanted into the rostro-dorsal and caudal-ventral hippocampus of TG1576 mice at 16 MPT. The transplanted cells (marked by human-specific nuclear antigen (HNA) and the interneuron subtype marker, SST) persist and migrate throughout the hippocampus. In addition, the transplanted cells project extensively to surrounding areas as marked by the human-TAU marker. [0057] FIGs. 44A-44B show human interneuron transplantation reduces the number of amyloid plaques in the TG2576 AD mouse model, according to some non-limiting embodiments of the present disclosure. FIG. 44A shows quantification of plaque densities in the hippocampus at 3 different levels (rostral, middle and caudal) in vehicle-injected and human interneuron transplanted animals. FIG. 44B shows the effect of human cell transplantation in the average plaque size in the hippocampus of TG2576 mice. [0058] FIG. 45 shows human interneuron transplantation rescues animal survival in the TG2576 AD mouse model, according to some non-limiting embodiments of the present disclosure. Percentages of surviving mice since the time of cell transplantation in naive (NCAR) and TG2576 transgenic mice injected with vehicle (VEH) or human interneurons (CELL). [0059] FIGs. 46A-46B show human interneuron transplantation increases the power of gamma oscillations in the TG2576 AD mouse model during the resting phase, according to some non-limiting embodiments of the present disclosure. FIG. 46A shows relative power with respect to the resting phase of theta (4-12 Hz, left) and gamma (20-60 Hz) oscillations in non-carrier (NCAR, gray), vehicle injected transgenic (VEH, red), and human cell transplanted transgenic (CELL, blue) in 24 hr EEG recording. FIG. 46B shows absolute power of theta (4-12 Hz, left) and gamma (20-60 Hz) oscillations in NCAR (gray), vehicle injected (red), and human cell transplanted (blue). [0060] FIGs. 47A-47C show embryonic induction of mTor, according to some non-limiting embodiments of the present disclosure. In utero electroporation of a constitutively active form of Rheb, a main transducer of the mTor pathway. Expression plasmid of Rheb-CA and GFP is shown in FIG. 47A, and the electroporation method is illustrated in FIG. 47B (at E15.5). FIG. 47C shows GFP and phospho-S6 (a mTor indicator) expression in the medial prefrontal cortex (mPFC) at E18.5 (left). GFP can be used to screen for GFP+ pups at P1 (middle and right panels). [0061] FIGs. 48A-48B show histological validation of embryonic induction of mTor, according to some non-limiting embodiments of the present disclosure. FIG. 48A shows GFP, GFPA, and pS6 expression in the mPFC of two different animals at P30. GFAP is a marker of active gliosis, a hallmark of FCD. FIG. 48B shows higher magnification images of the examples in FIG. 48A. This illustrates differences in RhebCA-GFP expression in different animals, and the activation of pS6 and GFAP. [0062] FIGs. 49A-49D show neonatal induction of mTor, according to some non- limiting embodiments of the present disclosure. FIGs. 49A-49B show neonatal delivery of a constitutively active form of Rheb by AAVs. Diagram of an AAV backbone with Rheb-CA and GFP driven by the projection neuron CamKII promoter. AAVs were delivered into the mPFC in P0-P1 CD1 pups at several different doses. FIG. 49C shows RhebCA/GFP- expressing cells correspond to cortical projection neurons (marked by NeuroD2), but not to GABAergic interneurons (marked by Lhx6). FIG. 49D shows co-expression of GFP and phospho-S6 in transduced cells and induction of GFAP in the mPFC at P30. [0063] FIGs. 50A-50B show histological validation of the neonatal induction of mTor in immunosuppressed mice, according to some non-limiting embodiments of the present disclosure. FIG. 50A shows co-expression of GFP, Rheb, and phospho-S6 in transduced cells and induction of GFAP in the mPFC of Scid-beige mice at P30. FIG. 50B shows high magnification images showing co-expression of GFP and phospho-S6 (marked by arrows) in transduced cells in the medial mPFC. [0064] FIGs. 51A-51C show electrographic validation of the embryonic induction of mTor, according to some non-limiting embodiments of the present disclosure. FIG. 51A shows examples of generalized seizures recorded with superficial electrodes in animals embryonically induced with Rheb-CA. FIG. 51B shows average seizure rates from a cohort of 6 embryonically-induced animals (3 weeks recording). FIG. 51C shows daily seizure recording of 3 animals with generalized seizures. [0065] FIGs. 52A-52B shows electrographic validation of the neonatal induction of mTor, according to some non-limiting embodiments of the present disclosure. FIGs. 52A- 52B shows examples of epileptiform activity recorded at 2 months post-implant with cortical electrodes in CD1 (FIG. 52A) and Scid-beige (FIG. 52B) animals induced with Rheb-CA AAVs neonatally. DETAILED DESCRIPTION [0066] Provided herein are methods of treating seizure activity, e.g., mesial temporal lobe epilepsy (MTLE), using a cellular composition of pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells. In some embodiments, a substantial portion, e.g., at least 90%, of the cells of the cellular composition are post-mitotic. In general terms, a method of the present disclosure includes identifying a subject in need of treating seizure activity; and administering a therapeutically effective amount of a cellular composition enriched for pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells. In some embodiments, the cellular composition administered to the subject includes (or is enriched for) pallial, MGE-type GABAergic interneuron cells derived from pluripotent stem cells (e.g., hESCs). In some embodiments, at least 90% of the cells of the cellular composition administered to the subject are pallial MGE-type GABAergic interneuron cells derived from pluripotent stem cells. In some embodiments, the method reduces the frequency of seizures in the subject, e.g., by at least about 50% in some embodiments. In some embodiments, administering the pluripotent stem cell-derived, MGE- type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) can restore local inhibitory tone to reduce the frequency of seizures in the subject. In any method of the present disclosure, in some embodiments, the MGE-type inhibitory (e.g., GABAergic) neuron cells include MGE-type inhibitory (e.g., GABAergic) interneuron cells. In some embodiments, the MGE-type inhibitory (e.g., GABAergic) neuron cells are of the pallial lineage. In any method of the present disclosure, in some embodiments, the pluripotent stem cell-derived, MGE-type GABAergic neuron cells are pallial, MGE-type GABAergic interneuron cells. In some embodiments, the MGE-type inhibitory (e.g., GABAergic) neuron cells are of the subpallial lineage. In any method of the present disclosure, in some embodiments, the pluripotent stem cell-derived, MGE-type GABAergic neuron cells are subpallial, MGE-type GABAergic neuron cells. [0067] In some embodiments, the administered cells locally disperse, mature into cortical/hippocampal-type interneurons, and persist in the subject’s temporal lobe, e.g. hippocampus, for an extended duration. In some embodiments, the high proportion of post- mitotic cells in the administered cellular composition promotes a stable cell fate of the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) after administration to the subject. In some embodiments, administering the pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell- derived, pallial, MGE-type GABAergic interneuron cells) reduces granule cell dispersion and/or neuronal degeneration in the subject’s temporal lobe. In some embodiments, administering the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) treats seizure activity, e.g., MTLE, such as MTLE that does not respond to anti-seizure drugs. In some embodiments, methods of the present disclosure provide a cell therapy alternative to resection/ablation surgery for drug-resistant MTLE. In some embodiments, administration of the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) to the subject’s brain (e.g., hippocampus, cortex, and/or amygdala) provides a targeted treatment for the seizure activity that minimizes side effects such as behavioral abnormalities and/or adverse immunological reactions by the subject. In some embodiments, the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) are administered to one or more regions of the temporal lobe: hippocampus, subiculum, entorhinal cortex, and/or parahippocampal gyrus. In some embodiments, the interneurons, precursors, and/or pluripotent stem cells, are genetically modified to evade the recipient's immune system (e.g., immune-cloaking). Terms [0068] Unless indicated otherwise, terms have their customary and ordinary meaning as understood by one of ordinary skill in the art in view of the present disclosure. [0069] “Seizure” or “seizure activity” as used herein has its customary and ordinary meaning as understood by one of ordinary skill in the art in view of the present disclosure. A seizure can include an uncontrolled, abnormal and/or synchronous brain activity, and/or one or more symptoms thereof. Unless indicated otherwise, reference to a seizure includes epileptic seizure-like discharges or epileptiform activity in the brain. A seizure may cause one or more of changes in the level of consciousness, behavior, memory, or emotional states. The seizure can be convulsive or non-convulsive. The seizure can be provoked or unprovoked. A seizure can include a focal seizure (e.g., focal aware seizure and/or focal impaired awareness seizure) or a focal to bilateral tonic-clonic seizure. [0070] “Focal onset seizure” or “focal seizure” as used herein has its customary and ordinary meaning as understood by one of ordinary skill in the art in view of the present disclosure, and denotes a seizure that occurs in or originates from one hemisphere or a subpart thereof of a subject’s brain. “Generalized seizure” as used herein has its customary and ordinary meaning to one of ordinary skill in the art in view of the present disclosure, and denotes a seizure that affects the whole brain or that is not limited to one hemisphere. A focal onset seizure can become generalized in some cases. A focal onset seizure can include a focal aware seizure and/or focal impaired awareness seizure. [0071] “Epilepsy” as used herein has its customary and ordinary meaning as understood by one of ordinary skill in the art in view of the present disclosure. An epilepsy refers to a disorder characterized by recurring seizures. “Focal epilepsy” refers to recurring seizures that affect one hemisphere or a subpart thereof of a subject’s brain. [0072] “Cellular composition” as used herein refers to an isolated collection or population of cells. The composition can include, without limitation, primary cells, stem cells, cells differentiated from stem cells, and cell lines. The cells of the composition can be suspended in, adhered to and/or embedded in any suitable medium or substrate. [0073] A “progenitor” or “progenitor cell” as used herein refers to a mitotic cell that is differentiating from a pluripotent stem cell, and is capable of further differentiating into a terminally-differentiated cell (e.g., as determined by changes in marker expression). A progenitor cell in some embodiments can differentiate into a desired terminally-differentiated cell (“on target”), or terminally-differentiated cell that is not desired (“off target”). [0074] “MGE-type” as used herein with reference to progenitors, lineages, neurons, and interneurons, refers to cells that express markers expressed by cells in the MGE region of the developing brain, or by neurons differentiated from cells of the MGE region. In general, MGE progenitor cells express markers such as, Foxg1, homeobox gene Nkx2.1, LIM-homeobox genes Lhx6, Lhx7, or Lhx8. MGE progenitor cells are capable of differentiating into interneurons and/or projection neurons under suitable differentiation conditions. [0075] “Pluripotent stem cell” or “pluripotent cell” refers to a cell that has the ability, under appropriate conditions, of producing progeny of several different cell types that are derivatives of any one of the three germinal layers (endoderm, mesoderm, and ectoderm). Pluripotent stem (PS) cells are capable of forming teratomas. Examples of pluripotent stem cells are embryonic stem (ES) cells, embryonic germ stem (EG) cells, embryonal carcinoma stem (EC) cells, and induced pluripotent stem (iPS) cells. PS cells may be from any one of a variety of organisms, including, e.g., human; primate; non-human primate; canine; feline; murine; equine; porcine; avian; camel; bovine; ovine, and so on. [0076] “Express” as used herein refers to the presence of a gene product (e.g., mRNA and/or protein) in or associated with a cell or a group of cells at a level above a relevant reference level (e.g., a predetermined level for detecting the gene product, or a level of the gene product that effectively differentiates between populations of cells known to either express or not express the gene product). In some cases, the reference level is a background level of expression. [0077] As used herein, “post-mitotic” denotes a cell in a state after it has exited the cell cycle. Cell cycle exit may be reversible or irreversible. In some embodiments, a post-mitotic cell is terminally differentiated. A post-mitotic cell can be characterized by expression, or lack thereof, of one or more markers (e.g., Ki67, ASPM), and/or measuring incorporation, or lack thereof, of a nucleoside analog. [0078] “Effective amount” as used herein refers to an amount sufficient to bring about a desired result. “Therapeutically effective amount” as used herein refers to an amount sufficient for a therapeutic agent to bring about a therapeutically desired result. [0079] As used herein, “treat” or “treatment” refer to curing, preventing occurrence of, ameliorating, preventing deterioration of, reducing one or more symptoms of, and/or slowing the progress of a condition or disease. [0080] “Subject” or “individual” as used herein can be any one of a variety of animals, such as a mammal. Mammals include, but are not limited to, humans, primates, horses, pigs, cows, dogs, cats, mice and rats, etc. In some embodiments, a subject can be male or female. “Subject” and “patient” are used interchangeably herein. [0081] “Transforming growth factor betas”, “TGF-βs”, and “TGFBs” are used interchangeably herein to refer to the TGFB secreted proteins belonging to the subfamily of the transforming growth factor β (TGFβ) superfamily. TGFBs (TGFB1, TGFB2, TGFB3) are multifunctional peptides that regulate proliferation, differentiation, adhesion, and migration and in many cell types. The mature peptides may be found as homodimers or as heterodimers with other TGFB family members. TGFBs interact with transforming growth factor beta receptors (TGF-βRs, or TGFBRs) on the cell surface, which binding activates MAP kinase-, Akt-, Rho- and Rac/cdc42-directed signal transduction pathways, the reorganization of the cellular architecture and nuclear localization of SMAD proteins, and the modulation of target gene transcription. Inhibitors of TGFB signaling, can be readily be identified by any of a number of suitable assays, for example competitive binding assays for binding to TGFB or TGFB receptors, or functional assays, e.g. measuring suppression of activity of downstream signaling proteins such as MAPK, Akt, Rho, Rac, and SMADs, e.g., AR-Smad, etc. [0082] “Bone morphogenic proteins” or “BMPs” as used herein refers to the family of growth factors that is a subfamily of the transforming growth factor β (TGF β) superfamily. BMPs (e.g. BMP1, BMP2, BMP3, BMP4, BMP5, BMP6, BMP7, BMP8a, BMP8b, BMP9/GDF, BMP10, BMP11/GDF11, BMP12/GDF7, BMP13/GDF6, BMP14/GDF5, BMP15/GDF9B) were first discovered by their ability to induce the formation of bone and cartilage. BMPs interact with specific receptors on the cell surface, referred to as bone morphogenetic protein receptors (BMPRs). Signal transduction through BMPRs results in mobilization of members of the SMAD family of proteins, which in turn modulate transcription of target genes. Inhibitors of BMP signaling, can readily be identified by any of a number of suitable assays, for example competitive binding assays for binding to BMP or BMP receptors, or functional assays, e.g., measuring enhancement of activity of downstream signaling proteins such as relocalization of SMADs, such as, BR-Smad to the nucleus and transcriptional activation of downstream gene targets. [0083] “Wnts” as used herein refers to the family of highly conserved secreted signaling molecules which play key roles in both embryogenesis and mature tissues. The human Wnt gene family has at least 19 members (Wnt-1, Wnt-2, Wnt-2B/Wnt-13, Wnt-3, Wnt3a, Wnt-4, Wnt-5A, Wnt-5B, Wnt-6, Wnt-7A, Wnt-7B, Wnt-8A, Wnt-8B, Wnt-9A/Wnt- 14, Wnt-9B/Wnt-15, Wnt-10A, Wnt-10B, Wnt-11 Wnt-16). Wnt proteins modulate cell activity by binding to Wnt receptor complexes that include a polypeptide from the Frizzled (Fz) family of proteins and a polypeptide of the low-density lipoprotein receptor (LDLR)- related protein (LRP) family of proteins. Once activated by Wnt binding, the Wnt receptor complex will activate one or more intracellular signaling cascades. These include the canonical Wnt signaling pathway; the Wnt/planar cell polarity (Wnt/PCP) pathway; and the Wnt-calcium (Wnt/Ca2+) pathway. [0084] “Sonic hedgehog” and “shh” as used herein refers to a member of the Hedgehog (Hh) protein family, that is a secreted glycoprotein that undergoes post- translational modifications, including auto-catalytic cleavage and cholesterol coupling to amino-terminal peptide to form the fragment that possesses the signaling activity. Hh binds to the 12-step transmembrane protein Ptch (Ptch1 and Ptch2), thereby alleviating Ptch- mediated suppression of Smoothened (Smo). Activation Smo triggers a series of intracellular events that culminate in the stabilization of Gli transcription factors (Gli1, Gli2, and Gli3) and the expression of Gli-dependent genes that are responsible for cell proliferation, cell survival, angiogenesis, and invasion. [0085] “Notch” as used herein refers to a signaling receptor in the Notch signaling pathway that controls cell fate during development, cell survival and cell proliferation. The Notch receptor is a single-pass transmembrane receptor containing numerous tandem epidermal growth factor (EGF)-like repeats and three cysteine-rich Notch/LIN-12 repeats within a large extracellular domain. Notch receptors are activated by single-pass transmembrane ligands of the Delta, Serrated, Lag-2 (DSL) family. Mammalian Notch receptors undergo cleavage to form the mature receptor and also following ligand binding to activate downstream signaling. A furin-like protease cleaves the Notch receptors during maturation to generate juxtamembrane heterodimers that comprise a non-covalently associated extracellular subunit and a transmembrane subunit held together in an auto- inhibitory state. Ligand binding relieves this inhibition and induces cleavage of the Notch receptor by an ADAM-type metalloprotease and a gamma-secretase, the latter of which releases the intracellular domain (ICD) into the cytoplasm, allowing it to translocate into the nucleus to activate gene transcription. Cleavage by ADAM occurs within the non-ligand binding cleavage domain within the membrane proximal negative regulatory region. [0086] “CDK” or “cyclin dependent kinase” as used herein refers to a family of serine-threonine kinase proteins that regulate progression through the various phases of the cell cycle. CDKs use ATP as a substrate to phosphorylate diverse polypeptides in a sequence dependent manner. Cyclins are a family of proteins characterized by a homology region, containing approximately 100 amino acids, termed the “cyclin box” which is used in binding to, and defining selectivity for, specific CDK partner proteins. [0087] “MEK” as used herein refers to one of three kinases that are part of the MAP (mitogen-activated protein) kinase (MAPK) pathway that regulates cell proliferation and/or differentiation. The MAPK pathway encompasses a cascade of phosphorylation events involving three key kinases, namely Raf, MEK (MAP kinase kinase) and ERK (MAP kinase). Active GTP-bound Ras results in the activation and indirect phosphorylation of Raf kinase. Raf then phosphorylates MEK1 and 2. Activated MEK then phosphorylates its only known substrates, the MAP kinases, ERK1 and 2. Phosphorylated ERK dimerizes and then translocates to the nucleus where it accumulates. In the nucleus, ERK is involved in several important cellular functions, including but not limited to nuclear transport, signal transduction, DNA repair, nucleosome assembly and translocation, and mRNA processing and translation. Overall, treatment of cells with growth factors leads to the activation of ERK1 and 2 which results in proliferation and, in some cases, differentiation. [0088] As used herein with reference to a numerical value, “K” indicates units of a thousand, and “M” indicates units of a million. For examples “200K” indicates “200,000”, and “1.5M” indicates “1,500,000.” [0089] The singular terms “a,” “an,” and “the” include plural referents unless context clearly indicates otherwise. Similarly, the word “or” is intended to include “and” unless the context clearly indicates otherwise. The abbreviation, “e.g.” is used herein to indicate a non- limiting example. Thus, the abbreviation “e.g.” is synonymous with the term “for example.” The term “about” as used herein to, for example, define the values and ranges of molecular weights means that the indicated values and/or range limits can vary within ±20%, e.g., within ±10%, including within ±5%. The use of “about” before a number includes the number itself. For example, “about 5” provides express support for “5.” METHODS [0090] Provided herein are methods of treating seizure activity, e.g., mesial temporal lobe epilepsy (MTLE), in a subject in need thereof. With reference to FIG. 1A, a method of treating seizure activity is provided. The method 100a can include at block 110a identifying a subject in need of treating seizure activity. The method can further include at block 120a administering (e.g., intracranially administering) a therapeutically effective amount of a cellular composition comprising pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells, as described herein. The pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells can in some embodiments be post-mitotic cells, where for example, at least 90% of the cells are post-mitotic cells. In some embodiments, at least 50% of the cells of the composition express markers for MGE- type GABAergic neuron cells (e.g., express at least LHX6 and GAD1). In some embodiments, at least 50% of the cells of the composition express markers for pallial, MGE- type GABAergic interneuron cells (e.g., express LHX6, ERBB4, and GAD1). In any method of the present disclosure, in some embodiments, a cellular composition includes pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells. In some embodiments, at least 50% of the cells of the composition express markers for subpallial, MGE-type GABAergic neuron cells (e.g., at least 50% of the cells express LHX6, LHX8 or NKX2.1, and GAD1, and do not express ERBB4). With reference to FIG. 1B, a method 100b of the present disclosure can include: at block 110b identifying a subject in need of treating seizure activity. The method can further include at block 120b administering (e.g., intracranially administering) a therapeutically effective amount of a cellular composition comprising pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells, as described herein. [0091] A subject treated by the methods of the present disclosure can have hyperexcitability and/or hyperactivity in neurons or a network thereof. In some embodiments, the subject is suffering from hyperexcitability and/or hyperactivity in neurons or a network thereof, where the hyperexcitability and/or hyperactivity is associated with a neurological condition. In some embodiments, the subject has a neurological condition that is associated with neuronal hyperexcitability and/or hyperactivity in one or more brain regions. In some embodiments, the subject has a neurodegenerative disease, such as but not limited to Alzheimer’s disease (AD) or Parkinson’s disease (PD) that is associated with the neuronal hyperexcitability and/or hyperactivity. In some embodiments, the subject suffers from epileptic seizure-like discharges in the brain associated with Alzheimer’s disease, focal cortical dysplasia (FCD), or amnesic mild cognitive impairment (aMCI). In some embodiments, subject has AD and exhibits one or more symptoms of AD. In some embodiments, the AD subject has or exhibits symptoms of tauopathy. In some embodiments, the subject has schizophrenia, spasticity, and/or neuropathic pain that is associated with the neuronal hyperexcitability and/or hyperactivity. In some embodiments, the subject has a neuropsychiatric disorder associated with the neuronal hyperexcitability and/or hyperactivity. [0092] In some embodiments, the subject is suffering from hyperexcitability and/or hyperactivity in one or more brain regions, e.g., in the temporal lobe. In some embodiments, the subject is suffering from hyperexcitability and/or hyperactivity in the hippocampus. In some embodiments, the subject is suffering from hyperexcitability and/or hyperactivity in one or more of the following regions of the temporal lobe: hippocampus, subiculum, entorhinal cortex, and/or parahippocampal gyrus. [0093] In some embodiments, the subject is in need of treatment of seizures and/or symptoms thereof. In some embodiments, the seizure is convulsive. In some embodiments, the seizure is non-convulsive (e.g., is an absence seizure). In some embodiments, the seizure is a focal onset seizure, or a focal epilepsy. In some embodiments, the seizure is localized to and/or originates from the temporal lobe of the left or right hemisphere of the subject’s brain. In some embodiments, the seizure is localized to and/or originates from one or more subregions of the temporal lobe. In some embodiments, the seizure is localized to and/or originates from the subiculum, entorhinal cortex, and/or parahippocampal gyrus. In some embodiments, the seizure is localized to and/or originates from the hippocampus (e.g., left and/or right hippocampus) and/or from the amygdala (e.g., left or right amygdala). In some embodiments, the subject suffers from a focal onset seizure that develops into a generalized seizure. In some embodiments, the subject does not have a generalized seizure. In some embodiments, the subject has a chronic seizure (e.g., a recurring seizure). In some embodiments, the subject has an epilepsy, e.g., a focal epilepsy or a temporal lobe epilepsy. In some embodiments, the subject has temporal lobe epilepsy (TLE) (e.g., drug-resistant TLE). In some embodiments, the subject suffers from a neocortical onset focal epilepsy. In some embodiments, the subject suffers from focal seizure activity. In some embodiments, the subject has mesial temporal lobe epilepsy (MTLE). In some embodiments, the subject has AD with epileptic activity. In some embodiments, the subject has AD and has, or suffers from symptoms of, tauopathy. [0094] In some embodiments, the subject has been diagnosed as having or suffering from seizure activity. In some embodiments, the subject has been diagnosed to have one or more conditions underlying the seizures (e.g., an infection, disease, stroke, trauma, neurological disorder, metabolic disorder, developmental disorder, drug exposure, or stress). The subject can be identified as in need of treating seizure activity by any suitable option. In some embodiments, the subject is identified as having or suffering from seizure activity based on a clinical manifestation of symptoms of seizure. In some embodiments, the subject is experiencing or has experienced one or more symptoms of the seizure. In some embodiments, the subject is identified as suffering from seizure activity based on a subjective assessment of one or more symptoms of the seizure. In some embodiments, the subject is identified as suffering from seizure activity based on brain monitoring. In some embodiments, the subject is identified as suffering from seizure activity after undergoing one or more brain monitoring such as, without limitation, computed tomography (CT) scan, magnetic resonance imaging (MRI), MR spectroscopy (MRS), functional MRI (fMRI), electroencephalography (EEG), intracranial EEG, positron emission tomography (PET), and single photon emission computed tomography (SPECT). [0095] In some embodiments, the seizure activity is an electrographic seizure. In some embodiments, the subject is identified as having or suffering from electrographic seizures. In some embodiments, the electrographic seizure is detected using an EEG. In some embodiments, an electrographic seizure includes a spike train of about 1 Hz or more, e.g., about 2 Hz, about 3 Hz, about 4Hz, about 5 Hz or more, or at a frequency in a range defined by any two of the preceding values (e.g., 1-5 Hz, 2-5 Hz, 3-4 Hz, 3-5 Hz, etc.), for example, as detected by EEG. In some embodiments, an electrographic seizure includes a spike train having a duration of about 5 seconds or longer, e.g., about 10 seconds, about 15 seconds, about 20 seconds, about 30 seconds or longer, or a period of time in a range defined by any two of the preceding values (e.g., 5-30 seconds, 10-20 seconds, 15-30 seconds, 5-20 seconds, etc.). In some embodiments, an electrographic seizure includes an inter-event (or inter-spike train) interval of about 1 second or more, e.g., about 2 seconds, about 3 seconds, about 5 seconds, about 10 seconds, about 15 seconds, about 20 seconds, about 30 seconds or more, or a period of time in a range defined by any two of the preceding values (e.g., 1-30 seconds, 2-20 seconds, 3-30 seconds, 5-15 seconds, 5-30 seconds, etc.). [0096] In some embodiments, a chronic or recurring seizure can occur at one or more frequencies. In some embodiments, the seizure occurs at a frequency of once per 30 minutes or more, e.g., 2 times per 30 minutes or more, about 5 times per 30 minutes or more, e.g., about 10 times per 30 minutes or more, about 15 times per 30 minutes or more, about 20 times per 30 minutes or more, about 30 times per 30 minutes or more, about 50 times per 30 minutes or more, or at a frequency in a range defined by any two of the preceding values (e.g., 1-50 times/30 minutes, 2-30 times/30 minutes, 3-20 times/30 minutes, 5-15 times/30 minutes, 10-15 times/30 minutes, etc.). In some embodiments, the seizure occurs at a frequency of once per week or more, e.g., 2 times per week or more, about 5 times per week or more, about 10 times per week or more, about 15 times per week or more, about 20 times per week or more, about 30 times per week or more, about 50 per week times or more, or at a frequency in a range defined by any two of the preceding values (e.g., 1-50 times/week, 2-30 times/week, 3-20 times/week, 5-15 times/week, 10-15 times/week, etc.). In some embodiments, the seizure occurs at a frequency of once per month or more, e.g., 2 times per month or more, about 5 times per month or more, about 10 times per month or more, about 15 times per month or more, about 20 times per month or more, about 30 times per month or more, about 50 times per month or more, or at a frequency in a range defined by any two of the preceding values (e.g., 1-50 times/month, 2-30 times/month, 3-20 times/month, 5-15 times/month, 10-15 times/month, etc.). In some embodiments, the frequency at which the seizure occurs (without administering the therapeutic compositions of the present disclosure) does not vary substantially over a month, two months, 3 months, 4 months, 6 months, or over 12 months or more. In some embodiments, the frequency at which the seizure occurs (without administering the therapeutic compositions of the present disclosure) increases over a month, two months, 3 months, 4 months, 6 months, or over 12 months or more. [0097] The length of an episode of a seizure from which the subject is suffering can vary. In some embodiments, an episode of the seizure lasts for about 5 second or longer, e.g., about 10 seconds or longer, about 30 seconds or longer, about 60 seconds or longer, about 90 seconds or longer, about 120 seconds or longer, about 180 seconds or longer, about 4 minutes or longer, about 5 minutes or longer, about 10 minutes or longer, about 15 minutes or longer, about 20 minutes or longer, or about 30 minutes or longer, or a period of time in a range defined by any two of the preceding values. In some embodiments, an episode of the seizure lasts from about 5 second to about 30 minutes. In some embodiments, an episode of the seizure lasts from about 5-10 seconds, 10-30 seconds, 30-60 seconds, 60-90 seconds, 90- 120 seconds, 120-180 seconds, 3-4 minutes, 4-5 minutes, 5-10 minutes, 10-15 minutes, 15-20 minutes, or 20-30 minutes. [0098] In some embodiments, the seizure activity is a chronic condition. In some embodiments, the seizure activity is a provoked seizure, or a non-provoked seizure. In some embodiments, the seizure activity is associated with an infection, disease (e.g., a tumor), stroke, trauma, neurological disorder, metabolic disorder, developmental disorder, drug exposure (e.g., drug overdose), focal cortical dysplasia, tuberous sclerosis, or stress. In some embodiments, the seizure activity is due to a traumatic brain injury (e.g., to the temporal lobe), focal cortical dysplasia, tuberous sclerosis, or due to a neurological disorder. In some embodiments, the seizure activity is due to a stroke, a tumor, or a developmental disorder. In some embodiments, the subject has mesial temporal sclerosis. In some embodiments, the subject has hippocampal sclerosis, and/or an extrahippocampal sclerosis (e.g., sclerosis of the amygdala). In some embodiments, the subject has one or more lesions, e.g., epileptogenic lesions, in the brain. In some embodiments, the subject has one or more lesions, e.g., epileptogenic lesions, in the temporal lobe. In some embodiments, the subject has 1, 2, 3, 4, 5 or more lesions, e.g., epileptogenic lesions, in the brain (e.g., in the temporal lobe). In some embodiments, the subject has increased granule cell dispersion in the temporal lobe, e.g., in the hippocampus. In some embodiments, the cause of the seizure is unknown. [0099] In some embodiments, the seizure activity is resistant to a conventional anti-seizure therapy. In some embodiments, the subject’s seizure activity is not adequately treated after treatment with one, two or more anti-seizure therapies. In some embodiments, the subject has drug-resistant TLE, e.g., drug-resistant MTLE. Drug-resistant seizure or epilepsy as used herein has its ordinary and customary meaning as understood by one of ordinary skill in the art in view of the present disclosure. In some embodiments, drug- resistant TLE is resistant to treatment with carbamazepine or levetiracetam. [0100] In some embodiments, the method includes identifying mesial temporal sclerosis in the subject’s brain. In some embodiments, the method includes identifying hippocampal sclerosis, and/or an extrahippocampal sclerosis (e.g., sclerosis of the amygdala). In some embodiments, the method includes identifying a lesion, e.g., an epileptogenic legion, in the subject’s brain (such as in the temporal lobe). Any suitable option can be used to identify a lesion or mesial temporal sclerosis in the subject’s brain. In some embodiments, the method includes using one or more suitable imaging techniques (e.g., computed tomography (CT) scan, magnetic resonance imaging (MRI), MR spectroscopy (MRS), functional MRI (fMRI), electroencephalography (EEG), intracranial EEG, positron emission tomography (PET), and single photon emission computed tomography (SPECT), etc.) to identify mesial temporal sclerosis or a lesion, e.g., an epileptogenic legion, in the subject’s brain, before, concurrent to, and/or after administering the cellular composition. In some embodiments, the method includes using one or more suitable imaging techniques, as described herein, to determine that the mesial temporal sclerosis is reduced or eliminated after administering the cellular composition. In some embodiments, the method includes using one or more suitable imaging techniques, as described herein, to determine that the lesion is reduced or eliminated after administering the cellular composition. [0101] In some embodiments, the method includes using one or more suitable brain activity monitoring techniques to determine whether the subject exhibits seizure activity, e.g., before and/or after administering the cellular composition. In some embodiments, the method includes using one or more suitable brain activity monitoring techniques, as described herein, to determine that the frequency of seizures is reduced after administering the therapeutically effective amount of the cellular composition containing the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells). In some embodiments, the method includes performing one or more of computed tomography (CT) scan, magnetic resonance imaging (MRI), MR spectroscopy (MRS), functional MRI (fMRI), electroencephalography (EEG), intracranial EEG, positron emission tomography (PET), and single photon emission computed tomography (SPECT) on the subject. [0102] In some embodiments, seizure activity is measured by self-assessment of the frequency, severity and/or type of seizure experienced by the subject over a suitable time period. A subject can make a self-assessment of the frequency, severity and/or type of the seizure using any suitable option. In some embodiments, the subject has described the frequency, severity and/or type of seizure experienced over a suitable time period (e.g., daily, weekly, monthly, etc.) in a seizure diary. In some embodiments, the subject has orally conveyed the frequency, severity and/or type of seizure experienced over a suitable time period (e.g., daily, weekly, monthly, etc.). In some embodiments, the method includes comparing the frequency, severity and/or type of seizure experienced by the subject before and after administration of the cellular composition as recorded by the subject in a seizure diary. [0103] In some embodiments, the method includes administering the therapeutically effective amount of the cellular composition to the temporal lobe of the subject. In some embodiments, the method includes administering the therapeutically effective amount of the cellular composition to the temporal lobe ipsilateral to seizure activity in the subject’s brain (e.g., ipsilateral to a focal onset seizure). In some embodiments, where the focal onset seizure is in or originates from the left hemisphere (e.g., left hippocampus, left amygdala) of the subject’s brain, the method includes administering the therapeutically effective amount of the cellular composition to the left temporal lobe. In some embodiments, where the focal onset seizure is in or originates from the right hemisphere (e.g., right hippocampus, right amygdala) of the subject’s brain, the method includes administering the therapeutically effective amount of the cellular composition to the right temporal lobe. In some embodiments, the method includes administering the cellular composition only to the temporal lobe ipsilateral to the focal onset seizure. In some embodiments, the method includes administering the therapeutically effective amount of the cellular composition to the temporal lobe bilaterally. In some embodiments, the cellular composition comprises genetically modified or gene edited cells, e.g., to evade the recipient's immune system, as described herein. [0104] In some embodiments, the cellular composition is administered as one or more deposits in the subject’s brain. In some embodiments, the cellular composition is administered as 1, 2, 3, 4, 5, 6, 7, 8 or more deposits in the subject’s brain. In some embodiments, the method include administering the cellular composition to one or more sites, e.g., 2, 3, 4, 5, 6, 7, 8, or more sites, in the hippocampus, cortex, subiculum, entorhinal cortex, parahippocampal gyrus, and/or amygdala. In some embodiments the cellular composition is administered to one or more distinct sites (e.g., target sites) within the temporal lobe (e.g., the hippocampus, subiculum, entorhinal cortex, parahippocampal gyrus, and/or amygdala) ipsilateral to the focal onset seizure. Suitable sites within the temporal lobe include, without limitation, the hippocampus, cortex, amygdala, subiculum, entorhinal cortex, and/or the parahippocampal gyrus. In some embodiments, the cellular composition is administered to one or more sites in the temporal lobe ipsilateral to the focal onset seizure. In some embodiments, the cells are administered to at least 1, 2, 3, 4, 5, 6, 7, or 8 or more different sites within the subject’s temporal lobe ipsilateral to the focal onset seizure. In some embodiments, administration of the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) to the subject’s brain (e.g., temporal lobe: hippocampus, subiculum, entorhinal cortex, and parahippocampal gyrus) provides a targeted treatment for the seizure activity that minimizes side effects such as behavioral abnormalities. [0105] In some embodiments, the cells of the composition are administered to, around, or distal to, a site of mesial temporal sclerosis in the subject’s brain. In some embodiments, the number of cells administered (per hemisphere or per deposit) depends on the size and/or extent of mesial temporal sclerosis in the subject’s brain. [0106] In some embodiments, the cells of the composition are administered to, around, or distal to, one or more sites of a lesion, e.g., epileptogenic lesion, in the subject’s brain (e.g., temporal lobe). In some embodiments, the number of cells administered (per hemisphere or per deposit) depends on the size and/or extent of a lesion (e.g., epileptogenic lesion). [0107] In some embodiments, the cells of the composition are administered to, around, or distal to, one or more sites within the subject’s brain identified by functional neuroimaging. In some embodiments, the cells of the composition are administered to, around, or distal to, one or more sites identified as a seizure onset zone using functional neuroimaging. In some embodiments, the cells of the composition are administered to, around, or distal to, one or more sites identified as an epileptogenic zone using functional neuroimaging. Any suitable option for functional neuroimaging can be used. In some embodiments, functional neuroimaging comprises one or more of PET, SPECT, magnetoencephalogram/magnetic source imaging (MEG/MSI), diffusion tensor imaging (DTI), fMRI, fMRI-EEG, MR spectroscopy (MRS), arterial spin labeling (ASL). In some embodiments, the subject does not or is not known to have a mesial temporal sclerosis or a lesion. [0108] Any suitable volume of the cellular composition can be administered per deposit. In some embodiments, the cellular composition is delivered in a volume of, of about, or of at most 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 8, 6, 5, 4, 3, 2 μL per deposit, or of, of about, or of at least 0.1, 0.5, 0.8, 1, 1.2, 1.5, 2, 2.5, 3 μL per deposit, or a volume per deposit in a range defined by any two of the preceding values (e.g., 0.1-100 μL per deposit, 0.1-50 μL per deposit, 0.1-20 μL per deposit, 0.5-10 μL per deposit, 1.0-5 μL per deposit, 1.5 -4 μL per deposit, 1-2 μL per deposit, 2-4 μL per deposit, etc.). In some embodiments, the cellular composition is delivered in a volume of about 50 μL or less (e.g., 1-50 μL) per deposit. In some embodiments, the cellular composition is delivered in a volume of about 20 μL or less (e.g., 1-20 μL) per deposit. In some embodiments, the cellular composition is delivered in a volume of about 10 μL or less (e.g., 1-10 μL) per deposit. [0109] Any suitable number of the cells can be administered to the subject. In some embodiments, the cellular composition administered to the subject includes, per hemisphere, about 1 x 104 cells or more, about 2 x 104 cells or more, about 3 x 104 cells or more, about 5 x 104 cells or more, about 1 x 105 cells or more, about 2 x 105 cells or more, about 5 x 105 cells or more, about 1 x 106 cells or more, about 2 x 106 cells or more, about 5 x 106 cells or more, about 1 x 107 cells or more, about 2 x 107 cells or more, about 5 x 107 cells or more, about 1 x 108 cells or more, about 1 x 109 cells or more, about 2 x 109 cells or more, about 5 x 109 cells or more, about 1 x 1010 cells or more, about 2 x 1010 cells or more, about 5 x 1010 cells or more, about 1 x 1011 cells or more, about 2 x 1011 cells or more, about 5 x 1011 cells or more, about 1 x 1012 cells or more, or a number of cells within a range defined by any two of the preceding values (e.g., 3 x 104 - 1 x 1012 cells, 1 x 105 - 5 x 1011 cells, 3 x 105 - 1 x 1011 cells, 1 x 106 - 1 x 1010 cells, 3 x 104 – 2 x 106, or 1 x 107 - 1 x 109 cells, etc.). In some embodiments, the cellular composition administered to the subject includes, per hemisphere, from about 1 x 104 to about 1 x 108 cells, from about 2 x 104 to about 5 x 107 cells, from about 5 x 104 to about 1 x 107 cells, from about 1 x 105 to about 1 x 107 cells, from about 2 x 105 to about 5 x 106 cells, from about 5 x 105 to about 5 x 106 cells, from about 3 x 104 to about 1 x 1012 cells, from about 3 x 104 to about 1 x 1011 cells, from about 1 x 106 to about 1 x 1010 cells, or from about 3 x 104 to about 2 x 106 cells. In some embodiments, the cellular composition administered to the subject includes, per hemisphere, from about 1 x 105 to about 1 x 109 cells, from about 2 x 105 to about 5 x 108 cells, from about 5 x 105 to about 1 x 108 cells, from about 1 x 106 to about 1 x 108 cells, from about 2 x 106 to about 5 x 107 cells, from about 5 x 106 to about 5 x 107 cells, from about 3 x 105 to about 1 x 1012 cells, from about 3 x 105 to about 1 x 1011 cells, from about 1 x 106 to about 1 x 1010 cells, or from about 3 x 106 to about 5 x 107 cells. In some embodiments, the cellular composition administered to the subject includes, per hemisphere, about 1 x 107 cells to about 5 x 107 cells. [0110] In some embodiments, the number of cells administered to the subject per deposit is about 1 x 103 cells or more, about 2 x 103 cells or more, about 5 x 103 cells or more, about 1 x 104 cells or more, about 2 x 104 cells or more, about 5 x 104 cells or more, about 1 x 105 cells or more, about 2 x 105 cells or more, about 5 x 105 cells or more, about 1 x 106 cells or more, about 2 x 106 cells or more, about 5 x 106 cells or more, about 1 x 107 cells or more, about 1 x 107 cells or more, about 2 x 107 cells or more, about 5 x 107 cells or more, about 1 x 108 cells or more, about 1 x 109 cells or more cells, or a number of cells within a range defined by any two of the preceding values (e.g., 1 x 103 - 1 x 109, 1 x 104 - 1 x 108, 1 x 104 - 2 x 108, 1 x 105 - 1 x 107, 1 x 105 - 1 x 106, or 1 x 103 - 1 x 107 cells, etc.). [0111] In some embodiments, the cellular composition is divided equally for administering to multiple sites, such that each deposit includes approximately the same number of cells of the composition. In some embodiments, at least two different deposits include substantially different numbers of cells of the composition. In some embodiments, the number of cells administered in two different deposits differs by about 50% or less, e.g., about 40% or less, about 30% or less, about 20% or less, about 10% or less, about 5% or less, about 2% or less, or at most by a percentage within a range defined by any two of the preceding values (e.g., at most 2-50%, 2-40%, 5-30%, 5-20%, or 10-20%, etc.). [0112] In some embodiments, the number of cells administered to the subject is based on a scaling factor applied to the number of cells administered in preclinical studies using a species that is different from the subject. In some embodiments, the scaling factor takes into account a ratio of the volume of a brain region (e.g., hippocampus) between the species used in the preclinical studies and the species to which the subject belongs. In some embodiments, the species used in preclinical studies is a mouse and the subject is a human subject, where the ratio of the volume of a brain region (e.g., hippocampus) between the two species is between about 100 and about 200, e.g., between about 120 and about 190, between about 130 and about 180, between about 140 and about 180, between about 150 and 170. In some embodiments, the species used in preclinical studies is a mouse and the subject is a human subject, where the ratio of the volume of a brain region (e.g., hippocampus) between the two species is between about 150 and 170. In some embodiments, the species used in preclinical studies is a mouse and the subject is a human subject, where the scaling factor is at least about 5 fold, e.g., at least about 6 fold, at least about 7 fold, at least about 8 fold, at least about 9 fold, at least about 10 fold, at least about 12 fold, at least about 14 fold, at least about 16 fold, at least about 18 fold, at least about 20 fold, at least about 25 fold, at least about 30 fold, at least about 50 fold, at least about 75 fold, at least about 100 fold, or a fold difference in a range defined by any two of the preceding values (e.g., 5-100 fold, 5-75 fold, 5-50 fold, 6-30 fold, 6-25 fold, 7-20 fold, 8-12 fold, 18-25 fold, etc.). In some embodiments, the species used in preclinical studies is a mouse and the subject is a human subject, where the scaling factor is about 10 fold. In some embodiments, the species used in preclinical studies is a mouse and the subject is a human subject, where the scaling factor is about 20 fold. [0113] The methods can employ any suitable option for administering the cellular composition to the subject’s brain. In general, the cells are administered intracranially. In some embodiments, the cells are administered using a stereotactic system. In some embodiments, administering includes injecting or implanting the cellular composition of the present disclosure into one or more target sites in the subject. In some embodiments, administering includes injecting or implanting the cellular composition of the present disclosure as one or more deposits in the subject’s brain, as described herein. In some embodiments, the cells of the present disclosure can be inserted into a delivery device, which facilitates introduction by injection or implantation of the cells into the subject’s brain. In some embodiments, such delivery devices include a tubular structure with an internal compartment, e.g., cannula, or catheters, for holding the cells and fluids and/or for injecting cells and fluids into the body of a subject. In some embodiments, the tubular structure additionally have a needle tip through which the cells can be introduced into the subject at a desired location. In some embodiments, the method includes using a cannula or catheter, or similar device, to administer the cellular composition to a subject (e.g., to the subject’s brain). In some embodiments, the method includes using a delivery device, as described herein, to administer the cellular composition to the subject (e.g., to the subject’s brain). In some embodiments, the method includes detecting the position of the delivery device (for example, the proximal end (e.g., the subject-facing end) of the delivery device) holding the cellular composition in the subject’s brain while, or for at least some portion of, administering the cellular composition to a subject. In some embodiments, the cellular composition includes a contrast agent that facilitates visualizing the position of the delivery device (for example, the proximal end (e.g., the subject-facing end) of the delivery device) in the subject’s brain during administration of the cellular composition. In some embodiments, the method includes using MRI to visualize the administration or delivery of the cellular composition (e.g., where the delivery vehicle includes an MRI contrast agent). [0114] The cellular composition of the present disclosure, or a portion thereof, can be in any suitable form for inserting into the delivery device. In some embodiments, the method includes formulating the cellular composition of the present disclosure, or a portion thereof, in a suitable form for inserting into the delivery device. For example, without limitation, the cells can be suspended in a solution or embedded in a support matrix when contained in such a delivery device. As used herein, the term “solution” includes a pharmaceutically acceptable vehicle, carrier, or diluent in which the cells remain viable. Pharmaceutically acceptable vehicles, carriers, and diluents can include, without limitation, saline, aqueous buffer solutions, solvents and/or dispersion media. In some embodiments, the solution is sterile and fluid to facilitate delivery. In some embodiments, the solution is stable under the conditions of manufacture and storage and preserved against the contaminating action of microorganisms such as bacteria and fungi through the use of, for example, parabens, chlorobutanol, phenol, ascorbic acid, thimerosal, and the like. In some embodiments, solutions of the present disclosure are prepared in a pharmaceutically acceptable carrier or diluent and, as required, other ingredients enumerated above, followed by filter sterilization. [0115] In some embodiments, the cellular composition is provided in a suitable delivery vehicle. In some embodiments, the delivery vehicle includes pharmaceutically acceptable salts, supplements, lipid polymers, non-ionic surfactants, and/or MRI contrast agents, such as, without limitation, gadolinium. In some embodiments, the delivery vehicle includes a non-ionic surfactant, e.g., a poloxamer. Suitable poloxamers include, without limitation, P124, P188, P237, P338, and/or P407. Any suitable amount of the poloxamer can be included in the delivery vehicle. In some embodiments, the delivery vehicle includes, v/v, about 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, or a percentage in a range defined by any two of the preceding values (e.g., 0.01%-2%, 0.05%-1%, 0.1%-0.5%, 0.2%-1.5%, etc.) of the poloxamer. In some embodiments, the delivery vehicle includes a poloxamer at 0.01%-2%, v/v. In some embodiments, the delivery vehicle includes a poloxamer at 0.1%-1%, v/v. [0116] In some embodiments, the delivery vehicle includes a preservation supplement (e.g., neural supplements, B27, N2, buffers, CSB, trehalose, sugars, salts, lipids, proteins, reducing agents, and/or Hypothermosol®). Any suitable amount of the preservation supplement can be included in the delivery vehicle. In some embodiments, the delivery vehicle includes, v/v, about 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or a percentage in a range defined by any two of the preceding values (e.g., 1-20%, 2-15%, 5-15%, 5-20%, etc.) of the preservation supplement. [0117] In some embodiments, the delivery vehicle includes a base medium. Any suitable based medium can be used. In some embodiments, the base medium includes, without limitation, aCSF, HBSS, MEM, DMEM, L-15, neurobasal medium, and combinations thereof. In some embodiments, the delivery vehicle includes a contrast agent. Any suitable contrast agent for imaging applications can be used. In some embodiments, the contrast agent is a paramagnetic contrast agent. In some embodiments, the contrast agent is an MRI contrast agent, including, without limitation, a gadolinium- or manganese-based contrast agent. In some embodiments, the contrast agent is an iodine-based or barium-based contrast agent. In some embodiments, the delivery vehicle includes one or more salts, e.g., sodium chloride, potassium chloride, etc. In some embodiments, the delivery vehicle includes a suitable buffer at physiological pH. [0118] In some embodiments, the cellular composition includes one or more salts, e.g., sodium chloride, potassium chloride, etc. In some embodiments, the cellular composition includes a salt (e.g., sodium chloride) at a concentration of, of about, or of at least 100, 120, 140, 160, 180, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, or 400 mM, or an osmolality of, of about, or of at most 600, 590, 580, 570, 560, 550, 540, 530, 520, 510, 500, 490, 480, 470, 460, 450, 440, 430, 420, 410, or 400 mM, or at a concentration in a range defined by any two of the preceding values (e.g., 100-600 mM, 200-500 mM, 150-450 mM, 250-500 mM, 300-450 mM, etc.). In some embodiments, the cellular composition includes sodium chloride at a concentration of 100-600 mM. In some embodiments, the cellular composition includes sodium chloride at a concentration of 100-600 mM. In some embodiments, the cellular composition has an osmolality of, of about, or of at least 100, 120, 140, 160, 180, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, or 500 mOsm/kg, or an osmolality of, of about, or of at most 1,000, 900, 800, 750, 700, 690, 680, 670, 660, 650, 640, 630, 620, 610, 600, 590, 580, 570, 560, 550, 540, 530, 520, 510, or 500 mOsm/kg, or an osmolality in a range defined by any two of the preceding values (e.g., 100-1,000 mOsm/kg, 100-900 mOsm/kg, 200-800 mOsm/kg, 200-600 mOsm/kg, 200-500 mOsm/kg, 250-500 mOsm/kg, 300-450 mOsm/kg, etc.). In some embodiments, the cellular composition has an osmolality of at least 200 mOsm/kg. In some embodiments, the cellular composition has an osmolality of at least 300 mOsm/kg. In some embodiments, the cellular composition has an osmolality of 100-900 mOsm/kg. In some embodiments, the cellular composition has an osmolality of 300-500 mOsm/kg. [0119] In some embodiments, the cellular composition includes a high concentration of cells (e.g., pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells) in suspension, e.g., when administered to the subject. Without being bound by theory, a sufficiently high concentration of cells in the cellular composition effectively raises the viscosity such that the cellular composition can be held stably in a defined volume at the tip of a cannula, or a catheter, or similar delivery device, where the rest of the internal compartment of the cannula can be filled with a cell-free liquid chase vehicle or inner stylet. In some embodiments, the cellular composition includes cells at a concentration of about 0.1 x 106 cells per microliter or more, e.g., about 0.2 x 106 cells per microliter, about 0.3 x 106 cells per microliter, about 0.5 x 106 cells per microliter, about 0.75 x 106 cells per microliter, about 1 x 106 cells per microliter, about 1.5 x 106 cells per microliter, about 2 x 106 cells per microliter, about 3 x 106 cells per microliter, about 4 x 106 cells per microliter or more, or at a concentration in a range defined by any two of the preceding values (e.g., 0.1 x 106-4 x 106 cells per microliter, 0.2 x 106-2 x 106 cells per microliter, 0.2 x 106-1.5 x 106 cells per microliter, 0.1 x 106-3 x 106 cells per microliter, etc.). In some embodiments, the cellular composition includes cells at a concentration of about 1 x 105 cells/μL or greater, and up to about 2 x 106 cells per microliter. In some embodiments, the cellular composition includes cells at a concentration of, of about, or of at least 0.1 x 106, 0.2 x 106, 0.3 x 106, 0.4 x 106, 0.5 x 106, 0.6 x 106, 0.7 x 106, 0.8 x 106, 0.9 x 106, 1 x 106, 1.1 x 106, 1.2 x 106, 1.3 x 106, 1.4 x 106, 1.5 x 106, 1.6 x 106, 1.7 x 106, 1.8 x 106, 1.9 x 106, or 2 x 106 cells per microliter, or at a concentration in a range defined by any two of the preceding values (e.g., 0.1 x 106 – 2 x 106 cells per microliter, 0.5 x 106 – 2 x 106 cells per microliter, 0.6 x 106 – 1.2 x 106 cells per microliter, 0.6 x 106 – 1 x 106 cells per microliter, 0.8 x 106 – 1.2 x 106 cells per microliter, etc.). In some embodiments, the cellular composition for administering to the subject includes cells at a concentration of about 0.8 x 106 cells per microliter or more (e.g., about 0.9 x 106 cells per microliter, about 1.0 x 106 cells per microliter, about 1.1 x 106 cells per microliter, about 1.2 x 106 cells per microliter, about 1.5 x 106 cells per microliter, including up to about 2.0 x 106 cells per microliter). In some embodiments, the cellular composition includes cells at a concentration of about 0.5 x 106 cells per microliter to about 1.5 x 106 cells per microliter. In some embodiments, the cellular composition includes cells at a concentration of about 0.6 x 106 cells per microliter to about 1.2 x 106 cells per microliter. In some embodiments, the cellular composition includes cells at a concentration of about 0.9 x 106 cells per microliter to about 1.2 x 106 cells per microliter. In some embodiments, the cellular composition includes cells at a concentration of about 1 x 106 cells per microliter. [0120] In some embodiments, the therapeutically effective amount of the cellular composition is administered at a concentration of about 1 x 105 cells/μL or greater. In some embodiments, the therapeutically effective amount of the cellular composition is administered at a concentration of about 1 x 105 cells/μL or greater, and up to about 2 x 106 cells per microliter. In some embodiments, the therapeutically effective amount of the cellular composition is administered at a concentration of, of about, or of at least 0.1 x 106, 0.2 x 106, 0.3 x 106, 0.4 x 106, 0.5 x 106, 0.6 x 106, 0.7 x 106, 0.8 x 106, 0.9 x 106, 1 x 106, 1.1 x 106, 1.2 x 106, 1.3 x 106, 1.4 x 106, 1.5 x 106, 1.6 x 106, 1.7 x 106, 1.8 x 106, 1.9 x 106, or 2 x 106 cells per microliter, or at a concentration in a range defined by any two of the preceding values (e.g., 0.1 x 106 – 2 x 106 cells per microliter, 0.5 x 106 – 2 x 106 cells per microliter, 0.6 x 106 – 1.2 x 106 cells per microliter, 0.6 x 106 – 1 x 106 cells per microliter, 0.8 x 106 – 1.2 x 106 cells per microliter, etc.). In some embodiments, the therapeutically effective amount of the cellular composition is administered at a concentration of about 0.5 x 106 cells per microliter to about 2 x 106 cells per microliter. In some embodiments, the therapeutically effective amount of the cellular composition is administered at a concentration of about 0.6 x 106 cells per microliter to about 1.2 x 106 cells per microliter. In some embodiments, the therapeutically effective amount of the cellular composition is administered at a concentration of about 0.9 x 106 cells per microliter to about 1.2 x 106 cells per microliter. In some embodiments, the therapeutically effective amount of the cellular composition is administered at a concentration of about 1 x 106 cells per microliter. [0121] In some embodiments, a cellular composition, such as the cellular compositions of pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells described herein (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells), having a high concentration of cells is delivered to a subject using a delivery device, such as, but not limited to, a cannula or catheter. In some embodiments, delivering a cellular composition, such as the cellular compositions of pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells), to the subject involves loading the cellular composition from the proximal end of the delivery device (e.g., cannula) and displacing the cellular composition from the proximal end of the delivery device with a chase vehicle solution (e.g., a cell-free liquid chase vehicle), or inner stylet, such that the desired volume of the cellular composition is expelled from the delivery device outlet at the proximal end. As used herein, “proximal” refers to a position along the delivery device (e.g., cannula) that is closer to the subject to which the cellular composition is being delivered than a position that is “distal”. In some embodiments, a delivery device (e.g., cannula) is configured to deliver the cellular composition, where the delivery device includes the cellular composition at the proximal portion, and a chase vehicle solution that fills the rest of the internal compartment of the delivery device. In some embodiments, the cellular composition is loaded at the proximal portion of the delivery device (e.g., cannula) and a chase vehicle solution fills the rest of the internal compartment of the delivery device. In some embodiments, the chase vehicle solution includes the same pharmaceutically acceptable carrier as the cellular composition. In some embodiments, the chase vehicle solution is a cell-free liquid composition that includes the same pharmaceutically acceptable carrier as the cellular composition. In some embodiments, the chase vehicle solution (or liquid chase vehicle) is the same as the delivery vehicle in which the cellular composition is provided for administration to a subject, but in a cell-free format. In some embodiments, the chase vehicle solution has a lower viscosity than the cellular composition. In some embodiments, the delivery device (e.g., cannula) is connected at the distal end to a displacement device (e.g., syringe or stylet traversing the inner lumen of the cannula) configured to expel the cellular composition from the cannula, where the syringe volume is filled with the chase vehicle solution. In some embodiments, the chase vehicle is not required (e.g., where the cellular composition is displaced by a stylet positioned in the cannula and configured to push the cellular composition out of the proximal end of the cannula). In some embodiments, the displacement device is attached to a pump configured to drive the syringe plunger and thereby expel the cellular composition from the delivery device (e.g., cannula) in a controlled manner. In some embodiments, the cellular composition is stably held in the delivery device (e.g., cannula) for a sufficient period of time to allow delivery to the subject. For example, substantially all of the cells remain in the volume at the end or tip of the delivery device (e.g., cannula) at which the composition is initially placed for a suitable period of time before administering to a subject. In some embodiments, the cellular composition is stably held in the cannula, before administering to a subject, for about 0.5 hours or more, e.g., about 1 hour, about 2 hours, about 3 hours, about 4 hours, about 6 hours, about 8 hours, about 12 hours, about 18 hours, about 24 hours, about 36 hours, about 48 hours, about 72 hours, about 96 hours or longer, or for a length of time within a range defined by any two of the preceding values (e.g., 0.5-96 hours, 1-72 hour, 2-48 hours, 6-96 hours, etc.). [0122] In some embodiments, the cellular composition of the present disclosure has been cryopreserved before use. In some embodiments, the method includes obtaining cryopreserved cells that include the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) before administering. In some embodiments, the method includes thawing a cryopreserved cellular composition that contains the pluripotent stem cell-derived, MGE- type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) before administering. The cellular composition may be cryopreserved for any suitable length of time, for example, at least 1 week, 2 weeks, 3 weeks, 1 month, 2 months, 3 months, 4 months, 6 months, 9 months, 12 months, 18 months, 2 years, 5 years or more, or a length of time defined by any two of the preceding values (e.g., 1 week – 5 years, 2 weeks – 2 years, 1 month – 1 year, or 6 months to 2 years, etc.), before the administering. [0123] The pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) can be preserved in any suitable cryopreservation formulation. In some embodiments, a cryopreservation formulation includes a cryoprotective agent, an energy substrate, and supplements, that prevent intracellular icicle formation (e.g., 0.5–20% DMSO (e.g., 0.5-1%, 1-2%, 2-5%, 5-10%, 10-15%, or 15-20% DMSO)), protect cell membranes by association with the cell surface, scavenge free radicals while providing pH buffering, oncotic/osmotic support, and stable ionic concentrations at low temperatures. In some embodiments, the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) are cryopreserved before use. In some embodiments, cryopreserving the cellular composition includes, before placing the cells in a cryoformulation that contains DMSO, incubating the cells in a buffer containing high molecular weight disaccharides, amino acids, and proteins such that cellular membrane structures are physically and chemically stable across a range of temperatures (e.g., 0-37°C, such as 4°C) and over a range of time periods in the buffer (e.g., 1 minute to 4 hours or more, such as overnight, including 30 minutes). In some embodiments, the cells are incubated in the buffer at about 0°C or higher, e.g., about 2 °C, about 4°C, about 6°C, about 10°C, about 12°C, about 15°C, about 18°C, about 20°C, about 25°C, about 30°C, or about 37°C, or at a temperature in a range defined by any two of the preceding values (e.g., 0-37°C, 2-30°C, 2-6°C, 10-30°C, 2-10°C, etc.). In some embodiments, the cells are incubated in the buffer for about 1 minute or longer, e.g., about 5 minutes, about 10 minutes, about 20 minutes, about 30 minutes, about 45 minutes, about 60 minutes, about 1.5 hours, about 2 hours, about 3 hours, about 4 hours or longer, or overnight, or for an amount of time within a range defined by any two of the preceding values (e.g., 1 minute-4 hours, 1-60 minutes, 20-45 minutes, 1-4 hours, 10 minutes-1.5 hours, etc.). In some embodiments, cryopreserving the cells includes exposing the cells in the cryoformulation to an ambient temperature that is decreasing at a controlled rate, past the point of ice crystal nucleation, to about -20 to -80°C. In some embodiments, exposing the cells in the cryoformulation to an ambient temperature that is decreasing includes cooling the ambient temperature at a specified rate, such as about 0.5°C/min or faster, e.g., about 1°C/min, about 2°C/min, about 3°C/min, about 4°C/min, or about 5°C/min, or at a rate in a range defined by any two of the preceding values (e.g., 0.5-5°C/min, 0.5-2°C/min, 1- 4°C/min, 1-3°C/min, etc.). Exposing the cells in the cryoformulation to an ambient temperature that is decreasing at a controlled rate can be done using any suitable option, for example, without limitation, by placing the cells in a controlled rate freezer under conditions such that the ambient temperature is decreased at the controlled rate. In some embodiments, after freezing, the cells are stored at <-80°C, such as, without limitation, in liquid nitrogen vapor or liquid phase, e.g., at <-150°C. [0124] In some embodiments, the cryopreserved pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) are thawed by incubating the cryopreserved cells at 30-40°C (e.g., at, or at about 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40°C) for 0.5-5 minutes (e.g., for, or for about 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 minutes), and further rehydrating the cells for 0.5-2 minutes/mL (e.g., for, or for about 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, or 2 minutes/mL) in thaw medium. In some embodiments, the thaw medium contains a nuclease (e.g., DNase), supplements and sodium ions, to scavenge free radicals while maintaining high osmolarity in order to reduce the risk of rapid cell expansion and cellular membrane damage. Any suitable nuclease can be used. Suitable nucleases include, without limitation, DNase I, Benzonase®, Micrococcal nuclease. In some embodiments, the thaw medium contains a nuclease (e.g., DNase) at about 500 units/mL or more, e.g., about 750 units/mL, about 1000 units/mL, about 1500 units/mL, about 2000 units/mL, or an amount in a range defined by any two of the preceding values (e.g., 500-2000 units/mL, 750- 1500 units/mL, 500-1000 units/mL, etc.). In some embodiments, the thaw medium contains sodium ions at a concentration of, of about, or of at least 100, 150, 200, 250, 300, 350, 400, 450, 500, or 600 mM, or a concentration in a range defined by any two of the preceding values (e.g., 100-600 mM, 150-500 mM, 200-600 mM, 200-400 mM, 100-200 mM, etc.). [0125] In some embodiments, the thawed and rehydrated cells are further incubated before formulating in a delivery formulation. In some embodiments, the cells (e.g., after thawing and rehydrating) are incubated in a buffered solution that contains poloxamers, ions, and nutrients to facilitate cell membrane repair, restore intracellular electrochemical equilibrium, and maintain physiological pH balance. Suitable poloxamers include, without limitation, P124, P188, P237, P338, and/or P407. In some embodiments, the buffered solution includes sodium chloride at a concentration of, of about, or of at least 100, 150, 200, 250, 300, 350, 400, 450, 500, or 600 mM, or a concentration in a range defined by any two of the preceding values (e.g., 100-600 mM, 150-500 mM, 200-600 mM, 200-400 mM, 100-200 mM, etc.). In some embodiments, the buffered solution includes sodium chloride at a concentration in a range of 100-600 mM. In some embodiments, the buffered solution includes sodium chloride at a concentration in a range of 200-600 mM. In some embodiments, the cells (e.g., with or without prior cryopreservation) are incubated in a buffered solution that contains poloxamers, ions, and nutrients before administering to a subject, as described herein. The cells can be incubated in the buffered solution at any suitable concentration, including at a high concentration while minimizing shear stress and reducing cell aggregation. In some embodiments, the cells are incubated in the buffered solution at a concentration of about 0.1 x 106 cells/ μL or higher, e.g., about 0.5 x 106 cells/mL, about 1 x 106 cells/mL, about 2 x 106 cells/mL, about 5 x 106 cells/mL, about 10 x 106 cells/mL, about 20 x 106 cells/mL, about 50 x 106 cells/mL, about 100 x 106 cells/mL, about 200 x 106 cells/mL, or about 300 x 106 cells/mL, or at a concentration in a range defined by any two of the preceding values (e.g., 0.1 x 106 cells/mL-300 x 106 cells/mL, 0.2 x 106 cells/mL-200 x 106 cells/mL, 0.5 x 106 cells/mL-100 x 106 cells/mL, 1 x 106 cells/mL- 300 x 106 cells/mL, 2 x 106 cells/mL-200 x 106 cells/mL, etc.). The cells can be incubated in the buffered solution for any suitable time period (e.g., after thawing and rehydrating). In some embodiments, the cells are incubated in the buffered solution for about 0.5 hours or more, e.g., about 1 hour, about 2 hours, about 5 hours, about 10 hours, about 15 hours, about 20 hours, about 30 hours, or for a time period in a range defined by any two of the preceding values (e.g., 0.5-30 hours, 1-30 hours, 1-20 hours, 2-20 hours, 1-10 hours, etc.). The cells can be incubated in the buffered solution at any suitable temperature. In some embodiments, the cells are incubated in the buffered solution at about 0°C or higher, e.g., about 2 °C, about 4°C, about 6°C, about 10°C, about 12°C, about 15°C, about 18°C, about 20°C, about 25°C, or at a temperature in a range defined by any two of the preceding values (e.g., 0-25°C, 2- 25°C, 2-6°C, 10-20°C, 2-10°C, etc.). [0126] In some embodiments, the cells (with or without prior cryopreservation) can be further held or stored for a second time period before administering to a subject. In some embodiments, the cells (with or without prior cryopreservation) can be further held or stored for a second time period, for example, for up to 1-7 days (e.g., 1, 2, 3, 4, 5, 6, 7 days, etc.) at 0-37°C (e.g., 4°C, 12°C, 20°C, 25°C, 37°C, etc.) before administering to a subject. In some embodiments, the cellular composition (e.g., thawed cellular composition) can be further stored with high viability and recovery at 0-37°C for up to 1-7 days when held in the buffered solution to allow long-term stability of the cells. In some embodiments, the method includes holding (or storing) the cellular composition (e.g., thawed cellular composition) for 1-7 days (e.g., about 1, 2, 3, 4, 5, 6, or about 7 days, etc.) at 0-37°C (e.g., about 4°C, 12°C, 20°C, 25°C, or about 37°C, etc.) before administering to a subject. In some embodiments, the method includes holding (or storing) the cellular composition (e.g., thawed cellular composition) for up to about 5 days before administering to a subject. In some embodiments, the method includes holding (or storing) the cellular composition (e.g., thawed cellular composition) for up to about 5 days at about 4°C before administering to a subject. In some embodiments, the method includes holding (or storing) the cellular composition (e.g., thawed cellular composition) for up to about 7 days before administering to a subject. In some embodiments, the method includes holding (or storing) the cellular composition (e.g., thawed cellular composition) for up to about 7 days at about 4°C before administering to a subject. In some embodiments, the lower the temperature at which the cells (e.g., thawed cells) are held or stored, the longer the cells can be held or stored before administering to a subject. In some embodiments, the method incudes holding the cells (e.g., thawed cells) at a temperature of, of about, or of at most 2, 4, 6, 8, 10, 12, 15, 17, 18, 19, 20, 21, 22, 25°C, or at a temperature in a range defined by any two of the preceding values (e.g., 4-25 °C, 4-20°C, 10- 20°C, 8-15°C, 4-12°C, 2-18°C, etc.), or at room temperature before administering to a subject. The thawed cellular composition can be held (or stored) at any suitable stage between after thawing and delivering to the subject. In some embodiments, the cellular composition (e.g., thawed cellular composition) is held (or stored) before loading into a delivery device (e.g., a cannula), in a suitable compartment (e.g., a tube, a syringe for attaching to a cannula, etc.). In some embodiments, the cellular composition (e.g., thawed cellular composition) is held (or stored) after loading into a delivery device (e.g., a cannula) and before delivering to the subject. In some embodiments, the cells (e.g., thawed and incubated cells) are further concentrated (e.g., before loading the cells into a delivery device, as described herein) to, to about, or to at least 0.1 x 106 cells per microliter (e.g., 0.1 x 106-4 x 106 cells per microliter). In some embodiments, the cells (with or without prior cryopreservation) are further concentrated and held or stored for the second time period in a suitable delivery vehicle, as described herein, before administering to the subject. [0127] In some embodiments, the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE- type GABAergic interneuron cells) are an unsorted population of cells differentiated from pluripotent stem cells. In some embodiments, the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE- type GABAergic interneuron cells) are a sorted population of cells differentiated from pluripotent stem cells. In some embodiments, the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells have been sorted (e.g., to enrich for the pallial or subpallial lineage) using one or more of flow cytometry, fluorescence activated cell sorting (FACS), or magnetic-activated cell sorting (MACS). [0128] In some embodiments, administration of the cellular composition reduces seizure frequency. In some embodiments, a method of the present disclosure provides for a reduction in the frequency of seizures by about 50% or more, about 55% or more, about 60% or more, about 65% or more, about 70% or more, about 75% or more, about 80% or more, about 85% or more, about 90% or more, about 95% or more, about 97% or more, about 99% or more, by about 100%, or by a percentage in a range defined by any two of the preceding values (e.g., 50-100%. 55-99%, 60-95%, 70-90%, or 75-95%, etc.), after administering the cellular composition. In some embodiments, administration of the cellular composition reduces the duration of seizure episodes. In some embodiments, a method of the present disclosure provides for a reduction in the duration of seizure episodes by about 50% or more, about 55% or more, about 60% or more, about 65% or more, about 70% or more, about 75% or more, about 80% or more, about 85% or more, about 90% or more, about 95% or more, about 97% or more, about 99% or more, or about 100%, or by a percentage in a range defined by any two of the preceding values (e.g., 50-100%. 55-99%, 60-95%, 70-90%, or 75- 95%, etc.), after administering the cellular composition. In some embodiments, administration of the cellular composition reduces seizure intensity (or severity). In some embodiments, the intensity (or severity) of seizures is reduced by about 20% or more, about 25% or more, about 30% or more, about 35% or more, about 40% or more, about 45% or more, about 50% or more, about 55% or more, about 60% or more, about 65% or more, about 70% or more, about 75% or more, about 80% or more, about 85% or more, about 90% or more, about 95% or more, about 97% or more, about 99% or more, or about 100%, or by a percentage in a range defined by any two of the preceding values (e.g., 50-100%. 55-99%, 60-95%, 70-90%, or 75-95%, etc.), after administering the cellular composition. In some embodiments, seizure frequency, duration of seizure episodes, or seizure intensity (or severity) is determined based on a subjective assessment of the frequency of seizures, duration of seizure episodes, or intensity (or severity) of a seizure (e.g., the most severe seizure experienced in the last week, last month, etc.), respectively. In some embodiments, the seizure frequency, duration of seizure episodes, or seizure intensity (or severity) is determined based on a measurement of brain activity using, e.g., EEG, CT scan, MRI, fMRI, MRS, PET or SPECT before and/or after the administering. [0129] In some embodiments, administration of the cellular composition reduces spontaneous electrographic seizure activity in the subject. In some embodiments, co- administration of the cellular composition of the present disclosure with an anti-seizure medication may have a synergistic therapeutic effect. For example, without being bound by theory, a benzodiazepine anti-seizure medication may increase the affinity of the subject’s GABA receptors for GABA produced by the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE- type GABAergic interneuron cells). As used herein, co-administering two or more therapeutic agents to a subject includes administering a therapeutic agent such that the therapeutic agent effectively exhibits its therapeutic effect during any time interval in which one or more other therapeutic agent effectively exhibits their therapeutic effect. For example, co-administering can include administering one therapeutic agent before, at the same time as, or after administering a second therapeutic agent. In some embodiments, administration of the cellular composition reduces the dose of an anti-seizure medication, e.g., antiepileptic drug, required to treat the seizure in the subject. In some embodiments, administration of the cellular composition reduces the dose of an anti-seizure medication required to treat the seizure by about 20% or more, about 25% or more, about 30% or more, about 35% or more, about 40% or more, about 45% or more, about 50% or more, about 55% or more, about 60% or more, about 65% or more, about 70% or more, about 75% or more, about 80% or more, about 85% or more, about 90% or more, about 95% or more, about 97% or more, about 99% or more, or about 100%, or by a percentage in a range defined by any two of the preceding values (e.g., 20-100%, 25-99%, 30-95%, 30-90%, 40-90%, 50-80%, 60- 95%, 70-99%, etc.), after administering the cellular composition. In some embodiments, the patient does not require any further treatment with an anti-seizure medication, e.g., antiepileptic drug, for the seizure activity after administering the cellular composition to the subject. In some embodiments, a subject that is administered the cellular composition has about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95% or greater chance of reducing seizure frequency by 75% or more. In some embodiments, the therapeutic effect (e.g., reduction in seizure frequency, reduction in sclerosis, and/or reduction in lesion size) of administering the cellular composition to the subject is observed at least 3 months, 4 months, 5 months, 6 months, 7 months, 8 months, 9 months, 12 months, 15 months, 18 months 21 months, 24 months or longer after the administration. In some embodiments, the method includes measuring a therapeutic effect (e.g., reduction in seizure frequency, reduction in sclerosis, and/or reduction in lesion size) of administering the cellular composition to the subject. In some embodiments, administration of the cellular composition reduces tauopathy or one or more symptoms thereof (e.g., in a subject having AD). [0130] In some embodiments, the method includes detecting or measuring, e.g., non-invasively detecting or measuring, one or more therapeutic effects of administering the cellular composition to the subject. In some embodiments, the method includes measuring a reduction in seizure activity (e.g., seizure frequency and/or intensity) in the subject, as described herein. In some embodiments, the method includes using EEG to measure therapeutic effects of administering the cellular composition to the subject. In some embodiments, the method includes using one or more brain imaging techniques to measure one or more structural and/or metabolic changes in the subject’s brain indicative of a therapeutic effect of administering the cellular composition. In some embodiments, the method includes using one or more biomarkers of seizure activity to monitor, e.g., non- invasively monitor, the therapeutic effect. In some embodiments, the biomarkers of seizure activity include one or more blood-based biomarkers. In some embodiments, the method includes measuring the change in level of one or more of N-acetylaspartate (NAA), myoinositol, glutamate, γ-Aminobutyric acid (GABA) in the subject’s brain or a region thereof. In some embodiments, the method includes measuring the level of one or more of N-acetylaspartate (NAA), myoinositol, glutamate, γ-Aminobutyric acid (GABA) before and/or after administering the cellular composition. The metabolites in the brain can be detected using any suitable option. In some embodiments, the level of one or more of N- acetylaspartate (NAA), myoinositol, glutamate, γ-Aminobutyric acid (GABA) are detected in the subject’s brain using magnetic resonance spectroscopy (MRS). In some embodiments, the method includes measuring the change in one or more of volume, edema, blood flow, oxygen metabolism and/or glucose levels in the subject’s brain or a region thereof. The volume, edema, blood flow, oxygen metabolism and/or glucose levels can be measured using any suitable option. In some embodiments, the method includes using magnetic resonance imaging (MRI) and/or positron emission tomography (PET) to detect volume, edema, blood flow, oxygen metabolism and/or glucose levels in the subject’s brain or a region thereof. In some embodiments, the method includes measuring (e.g., non-invasively measuring) the therapeutic effect using one or more biomarkers of seizure activity. In some embodiments, the one or more biomarkers comprises N-acetylaspartate (NAA), myoinositol, glutamate, GABA, volume, edema, blood flow, oxygen metabolism, and glucose. [0131] In some embodiments, administration of the cellular composition reduces the extent of sclerosis, and/or the size of an epileptogenic lesion in the subject’s brain. In some embodiments, ministration of the cellular composition reduces the extent of sclerosis or size of an epileptogenic lesion in the subject’s brain by about 5% or more, e.g., 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or about 100%, or by a percentage in range defined by any two of the preceding values (e.g., 5-100%, 10-90%, 20-50%, 50-90%, 40-70%, 80- 100%, etc.) compared to the extent of sclerosis or size of the lesion before administering. The extent of sclerosis and/or size of the epileptogenic lesion can be determined using any suitable option. Suitable options include, without limitation, CT scan, MRI, MRS, EEG, PET, SPECT, or fMRI. In some embodiments, the method includes using one or more of a CT scan, MRI, MRS, EEG, PET, SPECT, or fMRI to detect the presence and/or measure the size of an epileptogenic lesion in the subject’s brain, before and/or after administering the cellular composition. In some embodiments, the method includes using one or more of a CT scan, MRI, MRS, EEG, PET, SPECT, or fMRI before administering the cellular composition, e.g., for diagnosis and/or localizing an onset zone (e.g., a seizure or epileptogenic onset zone). In some embodiments, the method includes using one or more of a CT scan, MRI, MRS, EEG, PET, SPECT, or fMRI after administering the cellular composition, e.g., to monitor therapeutic efficacy. In some embodiments, the method includes using one or more of a CT scan, MRI, MRS, EEG, PET, SPECT, or fMRI to determine a reduction in extent of sclerosis or size of an epileptogenic lesion in the subject’s brain after administering the cellular composition. [0132] In some embodiments, administration of the cellular composition increases or restores viable neurons in the subject’s brain or a region thereof. In some embodiments, the level of NAA correlates with viable neurons in the subject’s brain or a region thereof. In some embodiments, administration of the cellular composition increases the level of NAA in the subject’s brain or a region thereof. In some embodiments, administration of the cellular composition increases the level of NAA in the subject’s brain or a region thereof by about 5% or more, e.g., 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% or more, or by a percentage in a range defined by any two of the preceding values (e.g., 5-100%, 10-90%, 15-80%, 20-100%, 5-50%, 50-100%, etc.) relative to the level before administering. In some embodiments, administration of the cellular composition restores the level of NAA in the subject’s brain or a region thereof to a level comparable to (e.g., within 30%, 20%, 10%, 5% of, or substantially the same as) the level in a healthy subject or a subject that is not suffering from seizure activity. [0133] In some embodiments, administration of the cellular composition reduces inflammation in the subject’s brain or a region thereof. In some embodiments, the level of myoinositol correlates with inflammation in the subject’s brain or a region thereof. In some embodiments, administration of the cellular composition reduces the level of myoinositol in the subject’s brain or a region thereof. In some embodiments, administration of the cellular composition reduces the level of myoinositol in the subject’s brain or a region thereof by about 5% or more, e.g., 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or about 100%, or by a percentage in a range defined by any two of the preceding values (e.g., 5-100%, 10-90%, 15-80%, 20-100%, 5-50%, 5-20%, etc.) relative to the level before administering. In some embodiments, administration of the cellular composition restores the level of myoinositol in the subject’s brain or a region thereof to a level comparable to (e.g., within 30%, 20%, 10%, 5% of, or substantially the same as) the level in a healthy subject or a subject that is not suffering from seizure activity. [0134] In some embodiments, administration of the cellular composition reduces or restores neural excitation in the subject’s brain or a region thereof. In some embodiments, the level of glutamate correlates with inflammation in the subject’s brain or a region thereof. In some embodiments, administration of the cellular composition reduces the level of glutamate in the subject’s brain or a region thereof. In some embodiments, administration of the cellular composition reduces the level of glutamate in the subject’s brain or a region thereof by about 5% or more, e.g., 10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or about 100%, or by a percentage in a range defined by any two of the preceding values (e.g., 5-100%, 10-90%, 15-80%, 20-100%, 5-50%, 5-20%, etc.) relative to the level before administering. In some embodiments, administration of the cellular composition restores the level of glutamate in the subject’s brain or a region thereof to a level comparable to (e.g., within 30%, 20%, 10%, 5% of, or substantially the same as) the level in a healthy subject or a subject that is not suffering from seizure activity. [0135] In some embodiments, administration of the cellular composition restores GABAergic tone in the subject’s brain or a region thereof. In some embodiments, the level of GABA correlates with GABAergic tone in the subject’s brain or a region thereof. In some embodiments, administration of the cellular composition restores the level of GABA in the subject’s brain or a region thereof to a level comparable to (e.g., within 30%, 20%, 10%, 5% of, or substantially the same as) the level in a healthy subject or a subject that is not suffering from seizure activity. [0136] In some embodiments, the subject has a cognitive (or neurocognitive) impairment associated with the seizure activity. In some embodiments, the cognitive (or neurocognitive) impairment includes a memory impairment, including, without limitation, impairment in short-term memory, long-term memory, or working memory. In some embodiments, the memory impairment includes, without limitation, impairment in verbal and/or visuospatial memory. In some embodiments, the method includes performing one or more neurocognitive assessments of the subject before and/or after the administration. Any suitable neurocognitive assessment can be performed, including without limitation, tests for word retrieval, verbal memory, and/or visuospatial memory. [0137] In some embodiments, administration of the cellular composition ameliorates, reduces, or restores cognitive (or neurocognitive) impairment associated with the seizure activity in the subject. In some embodiments, administration of the cellular composition slows or prevents further deterioration of the neurocognitive capacity of the subject. In some embodiments, administration of the cellular composition at least partially restores the neurocognitive capacity of the subject to a level within a range of a healthy individual. In some embodiments, administration of the cellular composition at least partially improves the neurocognitive capacity of the subject compared to the level before administration. [0138] In some embodiments, administration of the cellular composition improves the quality of life of the subject. The quality of life can be measured using any suitable option. In some embodiments, the subject’s self-assessment of quality of life is used to measure improvement before and after administration of the cellular composition. In some embodiments, administration of the cellular composition reduces the risk of death associated with the seizure activity and/or symptoms thereof. [0139] Methods of the present disclosure can provide for delivery of, or transplanting, pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) to a host brain, where the cells are capable of functionally integrating into the endogenous host brain tissue. In some embodiments, about or at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.) of the administered cells persist in the host brain for, for about, or for at least 3, 6, 9, 12, 15, 18, 21, 24, 36, 48, 60, 72, months, or a period of time in a range defined by any two of the preceding values (e.g., 3-72 months, 6-60 months, 12-48 months, 6-12 months, etc.) after administration. In some embodiments, persistence or persistence rate denotes the percentage of transplanted cells that remain in the brain of the subject to whom the cellular composition has been administered, relative to the total number of cells administered. In some embodiments, the persistence rate of the administered cells in the host brain at 6 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15% , or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4- 8%, etc.). In some embodiments, the persistence rate of the administered cells in the host brain at 8 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.). In some embodiments, the persistence rate of the administered cells in the host brain at 10 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4- 10%, or 4-8%, etc.). In some embodiments, the persistence rate of the administered cells in the host brain at 12 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.). In some embodiments, the persistence rate of the administered cells in the host brain at 15 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1- 5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.). In some embodiments, the persistence rate of the administered cells in the host brain at 18 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.). In some embodiments, the persistence rate of the administered cells in the host brain at 24 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1- 15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.). In some embodiments, the persistence rate of the administered cells in the host brain at 36 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4- 10%, or 4-8%, etc.). In some embodiments, the persistence rate of the administered cells in the host brain at 48 months or later is, is about, or is at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.). In some embodiments, about, or at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1- 5%, 3-15%, 3-12%, 4-10%, or 4-8%, etc.) of the administered cells functionally integrate into the subject’s brain as GABAergic neurons. In some embodiments, about or at least 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15%, or a percentage in a range defined by any two of the preceding values (e.g., 0.1-15%, 0.5-10%, 1-5%, 3-15%, 3-12%, 4-10%, or 4- 8%, etc.) of the administered cells functionally integrate into the subject’s brain as GABAergic interneurons, e.g., where the administered composition includes pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells. In some embodiments, 3-15% of the administered cells functionally integrate into the subject’s brain as GABAergic interneurons, e.g., where the administered composition includes pluripotent stem cell- derived, pallial, MGE-type GABAergic interneuron cells. In some embodiments, about 3 % or more, 4% or more, 5% or more, 6% or more, 8% or more, 9% or more, 10% or more, or about 12% or more, or a percentage in a range defined by any two of the preceding values (e.g., 3-15%, 3-12%, 4-10%, or 4-8%, etc.) of the administered cells functionally integrate into the subject’s brain as GABAergic projection neurons, e.g., where the administered composition includes pluripotent stem cell-derived, subpallial, MGE-type GABAergic neuron cells. [0140] In some embodiments, the percentage of post-mitotic cells in the administered cellular composition is sufficiently high to result in a high percentage of the cells persisting in the transplanted brain retaining the MGE-type GABAergic neuron cell fate. In some embodiments, the cells of the cellular composition retain the pallial, MGE-type GABAergic interneuron cell fate after transplantation to the host brain. In some embodiments, the cells of the cellular composition retain the subpallial, MGE-type GABAergic neuron cell fate after transplantation to the host brain. In some embodiments, the high-percentage of post-mitotic cells in the administered cellular composition promotes a higher percentage of cells persisting in the transplanted brain that retain the MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate), for example, after, after about, or after at least 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 24, 36, 48, months, or a length of time in a range defined by any two of the preceding values (e.g., 3-48 months, 4-36 months, 6-24 months, 9-12 months, 12-48 months, etc.). In some embodiments, the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE- type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 55-95%, 60-85%, 90-98%, etc.) about 3 months or more after administration. In some embodiments, the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 55-95%, 60-85%, 90-98%, etc.) about 6 months or more after administration. In some embodiments, the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 55-95%, 60-85%, 90-98%, etc.) about 9 months or more after administration. In some embodiments, the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 55-95%, 60-85%, 90-98%, etc.) about 12 months or more after administration. In some embodiments, the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 55-95%, 60-85%, 90-98%, etc.) about 24 months or more after administration. In some embodiments, the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 55-95%, 60-85%, 90-98%, etc.) about 36 months or more after administration. In some embodiments, the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98%, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 55-95%, 60-85%, 90-98%, etc.) about 48 months or more after administration. In some embodiments, the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is, is about, or is at least 50%, about 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 years or more after administration. In some embodiments, the percentage of cells retaining a MGE-type GABAergic neuron cell fate (e.g., pallial, MGE-type GABAergic interneuron cell fate) among the cells persisting in the transplanted brain is in the range of 50-90%, about 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 years or more after administration. In some embodiments, the cells persisting in the subject and that retain a pallial, MGE-type GABAergic interneuron cell fate express one or more of GAD1, GAD2, LHX6, SOX6, NXPH1, ERBB4, SST, NPY, MEF2c, and ARX. In some embodiments, expression of one or more markers of a pallial interneuron lineage (e.g., ERBB4, SST, NPY, MAF, and/or MAFB) indicates retention of a pallial interneuron cell fate in the persisting cells. In some embodiments, expression of one or more markers of a MGE-type lineage (e.g., SOX6, and/or LHX6) indicates retention of a MGE- type GABAergic neuron cell fate in the persisting cells. In some embodiments, expression of one or more markers of a GABAergic neuron lineage (e.g., GAD1 and/or GAD2) indicates retention of a GABAergic neuron cell fate in the persisting cells. In some embodiments, expression of one or more markers of a subpallial interneuron lineage (e.g., LHX8 and/or NKX2.1) indicates retention of a subpallial neuron cell fate in the persisting cells. In some embodiments, detecting electrophysiological properties of a GABAergic neuron (e.g., inhibitory post-synaptic potential) indicates retention of a GABAergic neuron cell fate in the persisting cells. [0141] In some embodiments, the method includes administering one or more additional doses of the cellular composition to the subject after an initial administration of the therapeutically effective amount of the cellular composition. In some embodiments, the one or more additional doses is administered at about the same dose (e.g., same number of cells) as the initial dose. In some embodiments, the one or more additional doses is administered at a different dose (e.g., different number of cells) than the initial dose. In some embodiments, the therapeutically effective amount of the cellular composition in the one or more additional doses includes fewer cells than the number of cells in the therapeutically effective amount of the cellular composition in the initial dose. In some embodiments, the therapeutically effective amount of the cellular composition of the one or more additional doses includes at most about 100%, 95%, 90%, 80%, 70%. 60%, 50%, 40%, 30%, 20%, 10%, 5%, 1%, 0.1% or less, or a percentage in between any two of the preceding values (e.g., 0.1-100%, 1-95%, 5-90%, 10-80%, 10-70%, 20-60%, 30-50%, 10-50%, 10-30%, etc.), of the number of cells as the therapeutically effective amount of the cellular composition in the initial dose. In some embodiments, the therapeutically effective amount of the cellular composition of the one or more additional doses includes more cells than the number of cells in the therapeutically effective amount of the cellular composition in the initial dose. In some embodiments, the patient does not require any further administration of the cellular composition to treat the seizure activity after the initial dose. In some embodiments, the patient does not require any further treatment for the seizure activity after administering the cellular composition to the subject. [0142] In some embodiments, the method further includes co-administering an anti-seizure medication to the subject. The co-administered anti-seizure medication can be administered before, after, or concurrently with the administration of the cellular composition. In some embodiments, the co-administered anti-seizure medication is one suitable for treating generalized seizure. The anti-seizure medication can be administered using any suitable option. In some embodiments, administration is oral or parenteral. In some embodiments, administration is local or systemic. In some embodiments, administration is intravenous, intracranial, subcutaneous, intramuscular, intraperitoneal. In some embodiments, the anti-seizure medication includes one or more benzodiazepines. Suitable anti-seizure medications include, without limitation, Carbamazepine, Cenobamate, Clobozam, Clonazepam, Diazepam, Ethosuximide, Felbamate, Fenfluramine, Gabapentin, Lacosamide, Lamotrigine, Levetiracetam, Lorazepam, Midazolam, Oxcarbazepine, Phenobarbital, Phenytoin, Pregabalin, Primidone, Tiagabine, Topiramate, Valproic acid, Vigabatrin, Zonisamide. [0143] In some embodiments, the method includes any suitable option to reduce or minimize adverse immunological reactions by the subject (e.g., immune-cloaking). In some embodiments, one or more immunosuppressants are co-administered to the subject. In some embodiments, immunosuppressants promote long-term engraftment of allogeneic or autologous cells. Any suitable immunosuppressant can be administered to a subject, e.g., to promote engraftment of the transplanted cells herein. Suitable immunosuppressants include, without limitation, glucocorticosteroids (e.g., prednisolone, cortisone, prednisone, dexamethasone, etc.), calcineurin inhibitors (e.g., cyclosporin A, tacrolimus), and cytostatic agents (e.g., azathioprine, and mycophenolate mofetil (MMF)). In some embodiments, one or more immunosuppressants are administered to the subject before, at the same time as, or after administering the cellular composition to the subject. In some embodiments, the method includes administering an immunosuppressant to the subject at an initial dose before and/or after administering the cellular composition to the subject. In some embodiments, the method includes gradually reducing the dose of the immunosuppressant after a time period post-administration. The immunosuppressant can be administered to the subject at any suitable time period before administering the cellular composition to the subject. In some embodiments, the method includes administering an immunosuppressant to the subject for a time period of, of about, or of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 14, 17, 21, 24, or 28 days, or a number of days in a range defined by any two of the preceding values (e.g., 1-28 days, 2-24 days, 3-14 days, 4-10 days, etc.) before administering the cellular composition to the subject. The immunosuppressant can be administered to the subject for any suitable time period after administering the cellular composition to the subject. In some embodiments, the method includes administering an immunosuppressant to the subject for a time period of, of about, or of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 17, 21, 24, or 28 months, or a number of days in a range defined by any two of the preceding values (e.g., 1-28 months, 2-24 months, 3-14 months, 4-12 months, etc.) after administering the cellular composition to the subject. In some embodiments, the method includes administering an initial dose of an immunosuppressant to the subject for an initial time period of, of about, or of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 17, 21, 24, or 28 months, or a number of days in a range defined by any two of the preceding values (e.g., 1-28 months, 2-24 months, 3-14 months, 4-12 months, etc.) after administering the cellular composition to the subject, and then reducing the dose after the initial time period. In some embodiments, the method includes use of genetically modified pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells), as described herein, for example, to reduce an immunological response against the administered cellular composition by the subject. In some embodiments, the method includes immunosuppression by genetically modifying the interneurons, precursors, or pluripotent stem cells of the present disclosure. In some embodiments, the genetic modification contributes to evasion of the recipient's immune system by the transplanted or administered cells. Any suitable gene that inhibits the expression or activity of immune-activating genes can be mutated to reduce or abolish activity, or knocked out, and/or any suitable genetic modification that activates expression or activity of immune-inhibiting genes can be made in the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells (or a precursor thereof). In some embodiments, the method includes genetically modifying one or more genes to reduce or abolish activity, and/or knocking out one or more immune-activating genes (e.g., B2M, a HLA class I gene, and/or a HLA class II gene, etc.) in the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells (or a precursor thereof). In some embodiments, the method includes genetically modifying the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells (or a precursor thereof) to activate expression or activity of immune-inhibiting genes. In some embodiments, the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells (or a precursor thereof) are genetically modified to reduce or abolish expression of one or more of: B2M, a HLA class I gene, and/or a HLA class II gene. In some embodiments, the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells are genetically modified to knock out one or more of: B2M, a HLA class I gene, and/or a HLA class II gene. Genetically modifying the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells (or a precursor thereof) can be done using any suitable option for genetic modification and/or gene editing. Suitable options include, without limitation, viral infection (e.g., adeno-associated virus, adenovirus, herpes simplex virus, lentivirus, retrovirus, etc.), zinc finger nuclease, TALEN, CRISPR-Cas nuclease, etc. [0144] Also provided is a method of treating seizure activity, comprising: identifying a subject in need of treating seizure activity; and intracranially administering to the subject a cellular composition comprising: about 5 x 104 to about 1 x 1012 pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells at a concentration in a range of about 1 x 105 to about 4 x 106 cells/μL, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1, wherein 90% or more of the cells of the composition are post-mitotic cells; a poloxamer at 0.1-1%, v/v; and sodium chloride at 100- 600 mM. PLURIPOTENT STEM CELL-DERIVED, MGE-TYPE GABAERGIC NEURON CELLS [0145] The cellular composition for use in the present disclosure generally includes pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells). In some embodiments, the cellular composition is sufficiently enriched in the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) so as to provide a therapeutic result when administered in a therapeutically effective amount to a subject in need of treating seizure activity. In some embodiments, the cellular composition includes NRTX-1001 prepared by Neurona Therapeutics Inc. [0146] In some embodiments, the cellular composition is a composition enriched for MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells). In some embodiments, the combination of markers characteristic of MGE-type inhibitory (e.g., GABAergic) neuron cells includes at least LHX6 and GAD1. In some embodiments, about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the composition are MGE-type inhibitory (e.g., GABAergic) neuron cells. In some embodiments, about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50- 100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the composition are pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells. In some embodiments, at least 80% of the cells of the composition are pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells. In some embodiments, about 85% of the cells of the composition are pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells. In some embodiments, about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the composition express a combination of markers characteristic of pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells. In some embodiments, the combination of markers characteristic of pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells includes at least (i) LHX6, (ii) ERBB4, and (iii) GAD1. In some embodiments, the combination of markers characteristic of pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells includes at least two or more (e.g., any 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 or all) of: DLX6-AS1, GAD1, GAD2, LHX6, SST, SLC32A1, ARX, DLX1, DLX2, DLX5, MEF2C, ZEB2, SOX6, NXPH1, CXCR4, ACKR3, MAF, MAFB, and ERBB4. In some embodiments, the combination of markers characteristic of pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells includes at least (i) LHX6, (ii) ERBB4, (iii) GAD1, and optionally (iv) one or more of DLX6-AS1, GAD2, SST, SLC32A1, ARX, DLX1, DLX2, DLX5, MEF2C, ZEB2, SOX6, NXPH1, CXCR4, MAF, MAFB, and ACKR3. In some embodiments, at least 80% (e.g., about 80, 85, 90, 95% or more) of cells of the cellular composition express (i) LHX6, (ii) ERBB4, (iii) GAD1. In some embodiments, at least 50%, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or more, or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the cellular composition further express at least one of MAF and MAFB. In some embodiments, 20-55% or 20-30% of cells of the cellular composition express SST. [0147] In some embodiments, the cells in the composition are characterized by expression (or lack thereof) of one or more markers in a manner consistent with the cell type of interest, such as pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells capable of integrating into the host brain upon transplantation. Expression of a marker can refer to mRNA and/or protein expression. In some embodiments, the cellular composition is enriched for cells expressing two or more, or three or more, markers of a pallial, MGE-type inhibitory (e.g., GABAergic) interneuron lineage, as noted above. In some embodiments, about, or at least 45%, 50%, 52%, 54%, 56%, 57%, 58%, 60%, 62%, 64%, 66%, 68%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 85%, 90%, 95%, 97%, or about 100%, or a percentage within a range defined by any two of the preceding values (e.g., 45-100%, 50-100%, 50-80%, 60-90%, 75-100%, 80-100%, 85-98%, 90-95%, 90-100%, etc.), of the cells of the composition express LHX6. In some embodiments, about, or at least 45%, 50%, 52%, 54%, 56%, 57%, 58%, 60%, 62%, 64%, 66%, 68%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 85%, 90%, 95%, 97%, or about 100%, or a percentage within a range defined by any two of the preceding values (e.g., 45-100%, 50-100%, 50-80%, 60-90%, 75-100%, 80-100%, 85-98%, 90-95%, 90-100%, etc.), of the cells of the composition express GAD1. In some embodiments, about, or at least 45%, 50%, 52%, 54%, 56%, 57%, 58%, 60%, 62%, 64%, 66%, 68%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 85%, 90%, 95%, 97%, or about 100%, or a percentage within a range defined by any two of the preceding values (e.g., 45-100%, 50-100%, 60-90%, 75-97%, 80-100%, 85-98%, 90-95%, 90-100%, etc.), of the cells of the composition express ERBB4. In some embodiments, about, or at least 45%, 50%, 52%, 54%, 56%, 57%, 58%, 60%, 62%, 64%, 66%, 68%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 85%, 90%, 95%, 97%, or about 100%, or a percentage within a range defined by any two of the preceding values (e.g., 45-100%, 50-100%, 50-80%, 60-90%, 75-100%, 80-100%, 85- 98%, 90-95%, 90-100%, etc.), of the cells of the composition express LHX6 and ERBB4. In some embodiments, about, or at least 45%, 50%, 52%, 54%, 56%, 57%, 58%, 60%, 62%, 64%, 66%, 68%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 85%, 90%, 95%, 97%, or about 100%, or a percentage within a range defined by any two of the preceding values (e.g., 45- 100%, 50-100%, 50-80%, 60-90%, 75-100%, 80-100%, 85-98%, 90-95%, 90-100%, etc.), of the cells of the composition express LHX6 and GAD1. In some embodiments, about, or at least 45%, 50%, 52%, 54%, 56%, 57%, 58%, 60%, 62%, 64%, 66%, 68%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 85%, 90%, 95%, 97%, or about 100%, or a percentage within a range defined by any two of the preceding values (e.g., 45-100%, 50-100%, 50-80%, 60-90%, 75- 100%, 80-100%, 85-98%, 90-95%, 90-100%, etc.), of the cells of the composition express ERBB4 and GAD1. In some embodiments, about, or at least 45%, 50%, 52%, 54%, 56%, 57%, 58%, 60%, 62%, 64%, 66%, 68%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 85%, 90%, 95%, 97%, or about 100%, or a percentage within a range defined by any two of the preceding values (e.g., 45-100%, 50-100%, 50-80%, 60-90%, 75-100%, 80-100%, 85-98%, 90-95%, 90-100%, etc.), of the cells of the composition express LHX6, ERBB4, and GAD1. In some embodiments, the cellular composition is enriched for cells expressing LHX6, ERBB4, and/or GAD1, compared to before being differentiated in vitro (e.g., embryonic stem cells) or compared to during the differentiation in vitro (e.g., MGE-type progenitor cells). [0148] In some embodiments, about, or at least 45%, 50%, 52%, 54%, 56%, 57%, 58%, 60%, 62%, 64%, 66%, 68%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 85%, 90%, 95%, 97%, or about 100%, or a percentage within a range defined by any two of the preceding values (e.g., 45-100%, 50-100%, 60-90%, 75-97%, 80-100%, 85-98%, 90-95%, 90-100%, etc.), of the cells of the composition express at least one of MAF and MAFB. In some embodiments, about, or at least 45%, 50%, 52%, 54%, 56%, 57%, 58%, 60%, 62%, 64%, 66%, 68%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 85%, 90%, 95%, 97%, or about 100%, or a percentage within a range defined by any two of the preceding values (e.g., 45-100%, 50-100%, 60-90%, 75-97%, 80-100%, 85-98%, 90-95%, 90-100%, etc.), of the cells of the composition express MAF. In some embodiments, about, or at least 45%, 50%, 52%, 54%, 56%, 57%, 58%, 60%, 62%, 64%, 66%, 68%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 85%, 90%, 95%, 97%, or about 100%, or a percentage within a range defined by any two of the preceding values (e.g., 45-100%, 50-100%, 60-90%, 75-97%, 80-100%, 85-98%, 90-95%, 90-100%, etc.), of the cells of the composition express MAFB. [0149] In some embodiments, the cells of the cellular composition express two or more (e.g., any 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or all) markers for pallial, MGE-type inhibitory (e.g., GABAergic) interneurons selected from: DLX6-AS1, GAD1, GAD2, LHX6, SST, SLC32A1, ARX, DLX1, DLX2, DLX5, MEF2C, ZEB2, SOX6, NXPH1, CXCR4, ACKR3, MAF, MAFB, and ERBB4. In some embodiments, the cellular composition is enriched for cells expressing two or more (e.g., any 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or all) markers for GABAergic interneurons selected from: DLX6- AS1, GAD1, GAD2, LHX6, SST, SLC32A1, ARX, DLX1, DLX2, DLX5, MEF2C, ZEB2, SOX6, NXPH1, CXCR4, ACKR3, MAF, MAFB, and ERBB4, compared to before being differentiated in vitro (e.g., embryonic stem cells) or compared to during the differentiation in vitro (e.g., MGE-type progenitor cells). In some embodiments, about, at least, or at least about 45%, e.g., 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 97%, or about 100%, or a percentage within a range defined by any two of the preceding values (e.g., 45- 100%, 50-100%, 60-90%, 75-97%, 80-100%, 85-97%, 90-95%, 90-100%, etc.), of the cells of the cellular composition express two or more (e.g., any 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or all) markers for pallial, MGE-type inhibitory (e.g., GABAergic) interneurons selected from: DLX6-AS1, GAD1, GAD2, LHX6, SST, SLC32A1, ARX, DLX1, DLX2, DLX5, MEF2C, ZEB2, SOX6, NXPH1, CXCR4, ACKR3, MAF, MAFB, and ERBB4. [0150] In some embodiments, the cells of the cellular composition express one or more pan-neuronal markers selected from: DCX, MAPT, STMN2, C1orf61, and MAP2. In some embodiments, about, at least, or at least about at least about 45%, e.g., 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 97%, or about 100%, or a percentage within a range defined by any two of the preceding values (e.g., 45-100%, 50-100%, 60-90%, 75-97%, 80- 100%, 85-97%, 90-95%, 90-100%, etc.), of the cells of the cellular composition express one or more pan-neuronal markers selected from: DCX, MAPT, STMN2, C1orf61, and MAP2. [0151] In some embodiments, the cellular composition is depleted for cells expressing one or more markers that are indicative of an off-target cell type (e.g., a non- pallial, MGE-type inhibitory interneuron lineage). In some embodiments, at most 20% of the cells of the composition are subpallial neurons. In some embodiments, at most 15% of the cells of the composition are subpallial neurons. In some embodiments, the cellular composition is depleted for cells expressing one or more off-target markers selected from LHX8, OTX2, SP8, ISL1, NKX2-1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2. In some embodiments, the cellular composition is depleted for cells expressing any of the off-target markers selected from LHX8, OTX2, SP8, ISL1, NKX2-1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2. In some embodiments, about 50% or less, e.g., 45%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 3%, 1%, or about 0%, or a percentage within a range defined by any two of the preceding values (e.g., 50-0%, 45-1%, 45-5%, 35-10%, 50-3%, etc.), of the cells of the cellular composition express one or more off-target markers selected from LHX8, OTX2, SP8, ISL1, NKX2-1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2. In some embodiments, about 50% or less, e.g., 45%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 3%, 1%, or about 0%, or a percentage within a range defined by any two of the preceding values (e.g., 50-0%, 45-1%, 45-5%, 35-10%, 50-3%, etc.), of the cells of the cellular composition express any of the off-target markers selected from LHX8, OTX2, SP8, ISL1, NKX2-1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2. [0152] In some embodiments, the cellular composition is depleted for cells expressing one or more markers for MGE-type progenitor cells selected from: LHX8, NKX2-1, and VIM, compared to during the differentiation in vitro (e.g., compared to MGE- type progenitor cells). In some embodiments, about or at most 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 2%, 1% or less, or a percentage in a range define by any two of the preceding values (e.g., 80-1%, 60-5%, 50- 10%, 80-20%, 75-20%, 70-25%, 65-30%, etc.) of cells of the cellular composition express LHX8. In some embodiments, about, or at least 45%, 50%, 52%, 54%, 56%, 57%, 58%, 60%, 62%, 64%, 66%, 68%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 85%, 90%, 95%, 97%, or about 100%, or a percentage within a range defined by any two of the preceding values (e.g., 45-100%, 50-100%, 50-80%, 60-90%, 75-100%, 80-100%, 85-98%, 90-95%, 90- 100%, etc.), of the cells of the composition express LHX6, ERBB4, and GAD1, and the composition is further depleted for cells expressing LHX8. In some embodiments, about or at most 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 2%, 1% or less, or a percentage in a range define by any two of the preceding values (e.g., 80-1%, 60-5%, 50-10%, 80-20%, 75-20%, 70-25%, 65-30%, etc.) of cells of the cellular composition express NKX2-1. [0153] In some embodiments, the cellular composition is depleted for cells expressing one or more markers for glial cells selected from: SLC1A3, GFAP, OLIG1 and OLIG2, compared to before being differentiated in vitro (e.g., embryonic stem cells) or compared to during the differentiation in vitro (e.g., MGE-type progenitor cells). In some embodiments, about 5% or less, e.g., about 4%, about 3%, about 2%, about 1%, or about 0%, or a percentage in a range define by any two of the preceding values (e.g., 5-0%, 5-1%, 4- 1%, 3-1%, 5-2%, 4-2%, etc.) of cells of the cellular composition express OLIG2. [0154] In some embodiments, about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the composition are subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cells. In some embodiments, the subpallial, MGE-type GABAergic neuron cells include interneurons and/or projection neurons. In some embodiments, the combination of markers characteristic of a subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cell fate includes at least (i) LHX6, (ii) LHX8 and/or NKX2.1, and (iii) GAD1. In some embodiments, about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80- 100%, 85-95%, etc.) of the cells of the composition express at least LHX8 and/or NKX2.1. In some embodiments, about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the composition express at least (i) LHX6, (ii) LHX8 and/or NKX2.1, and (iii) GAD1. In some embodiments, a subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cell fate is characterized by a lack of ERBB4 expression. In some embodiments, the cellular composition is enriched for cells expressing two or more, or three or more, markers of a subpallial, MGE-type inhibitory (e.g., GABAergic) neuron lineage, as noted above. In some embodiments, the cellular composition is enriched for cells expressing LHX6, LHX8 and/or NKX2.1, and/or GAD1, compared to before being differentiated in vitro (e.g., embryonic stem cells) or compared to during the differentiation in vitro (e.g., MGE-type progenitor cells). In some embodiments, the cellular composition is depleted for cells expressing one or more markers that are indicative of an off-target cell type (e.g., a non-subpallial, MGE-type inhibitory neuron lineage). In some embodiments, at most 20% of the cells of the composition are pallial interneurons. In some embodiments, at most 15% of the cells of the composition are pallial interneurons. In some embodiments, the cellular composition is depleted for cells expressing one or more off-target markers selected from ERBB4, MAF, MAFB, OTX2, SP8, ISL1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2. In some embodiments, about 50% or less, e.g., 45%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 3%, 1%, or about 0%, or a percentage within a range defined by any two of the preceding values (e.g., 50-0%, 45-1%, 45-5%, 35-10%, 50-3%, etc.), of the cells of the cellular composition express one or more off-target markers selected from ERBB4, MAF, MAFB, OTX2, SP8, ISL1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2. In some embodiments, about 50% or less, e.g., 45%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 3%, 1%, or about 0%, or a percentage within a range defined by any two of the preceding values (e.g., 50-0%, 45-1%, 45-5%, 35-10%, 50-3%, etc.), of the cells of the cellular composition express any of the off- target markers selected from ERBB4, MAF, MAFB, OTX2, SP8, ISL1, VIM, KI67, ASPM, POU5F1, NANOG, OLIG1, OLIG2, PDGFRA, GFAP, SLC17A6, SLC17A7, NEUROD2. In some embodiments, about or at most 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 2%, 1% or less, or a percentage in a range define by any two of the preceding values (e.g., 80-1%, 60-5%, 50-10%, 80-20%, 75-20%, 70-25%, 65-30%, etc.) of cells of the cellular composition express ERBB4. In some embodiments, about or at most 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 2%, 1% or less, or a percentage in a range define by any two of the preceding values (e.g., 80-1%, 60-5%, 50-10%, 80-20%, 75-20%, 70-25%, 65-30%, etc.) of cells of the cellular composition express MAF and/or MAFB. In some embodiments, about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80- 100%, 85-95%, etc.) of the cells of the composition express at least (i) LHX6, (ii) LHX8 and/or NKX2.1, and (iii) GAD1, and the composition is further depleted for cells expressing ERBB4. In some embodiments, about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the composition express at least (i) LHX6, (ii) LHX8 and/or NKX2.1, and (iii) GAD1, and do not express ERBB4. In some embodiments, about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50-100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the composition express at least (i) LHX6, (ii) LHX8 and/or NKX2.1, and (iii) GAD1, and the composition is further depleted for cells expressing MAF or MAFB. In some embodiments, about 50% or more, e.g., 60%, 70%, 80%, 85%, 90%, 95%, 97%, 99% or about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 50- 100%, 60-99%, 70-95%, 80-100%, 85-95%, etc.) of the cells of the composition express at least (i) LHX6, (ii) LHX8 and/or NKX2.1, and (iii) GAD1, and do not express MAF or MAFB. [0155] The percentage of cells expressing markers, e.g., pallial, MGE-type interneuron markers (such as, without limitation, DLX6-AS1, GAD1, LHX6, SST, SLC32A1, ARX, DLX5, MEF2C, NXPH1, MAF, MAFB, and ERBB4), or non-pallial, MGE-type neuron markers in the cellular composition, can be determined, if desired, using any suitable option. In some embodiments, expression is determined by detecting a level of protein in the cells. Suitable options for measuring expression level of a protein include, without limitation, ELISA, Western blotting, radioimmunoassay, immunoprecipitation, immunostaining (including, e.g., immunohistochemistry and immunocytochemistry), flow cytometry or fluorescence activated cell sorting (“FACS”) analysis, and homogeneous time- resolved fluorescence (HTRF) assays. In some embodiments, expression is determined by detecting a level of mRNA. Suitable options for measuring expression level of a mRNA include, without limitation, Northern blot hybridization, ribonuclease RNA protection, in situ hybridization (ISH) (e.g., fluorescence in situ hybridization (FISH)), microarray analysis, reverse-transcription polymerase chain reaction (RT-PCR), high throughput or next generation sequencing. In some embodiments, the expression level of one marker is measured using an option that is different from that used to measure the expression level of another marker. For example, without limitation, one marker can be measured using immunohistochemistry, and another marker can be measured using FACS. As another example, without limitation, one marker can be measured using immunohistochemistry, and another marker can be measured using ISH or FISH. In some embodiments, the expression level of one marker is measured using an option that is the same as that used to measure the expression level of another marker. In some embodiments, any one or more characteristics (e.g., marker expression, mitotic state, migratory capacity, etc.) of the cells of the composition can be determined, if desired, for at least a subset of the cells of the composition. In some embodiments, a representative portion or subset of the cells of the composition are assayed to determine one or more characteristics (e.g., marker expression, mitotic state, migratory capacity, etc.) of the cells of the composition. [0156] In some embodiments, substantially all cells of the composition do not contain or do not express an exogenous MGE-type progenitor cell marker. The exogenous MGE-type progenitor cell marker can be any marker for MGE-type progenitor cells that is not native to the cells of the composition. In some embodiments, an exogenous MGE-type progenitor cell marker is a transgenic marker. In some embodiments, an exogenous MGE- type progenitor cell marker is an enhancer-promoter reporter gene, e.g., a fluorescent protein, such as a green fluorescent protein (GFP), expressed under an enhancer-promoter specific for MGE-type progenitor cell. In some embodiments, at most 30%, at most 20%, at most 15%, at most 10%, at most 5%, at most 3%, at most 2%, at most 1%, or about 0%, or at most a percentage in a range define by any two of the preceding values (e.g., at most 30-0%, at most 20-1%, at most 15-5%, at most 30-3%, etc.) of cells of the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) have an exogenous MGE-type progenitor cell marker. In some embodiments, substantially none of the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) has an exogenous MGE-type progenitor cell marker. [0157] In some embodiments, substantially all cells of the composition do not contain or express an exogenous marker. The exogenous marker can be any marker that is not native to the cells of the composition. In some embodiments, an exogenous marker is a transgenic marker. In some embodiments, an exogenous marker is an enhancer-promoter reporter gene, e.g., a fluorescent protein, such as a green fluorescent protein (GFP), expressed under an enhancer-promoter. In some embodiments, at most 30%, at most 20%, at most 15%, at most 10%, at most 5%, at most 3%, at most 2%, at most 1%, or about 0%, or at most a percentage in a range define by any two of the preceding values (e.g., at most 30-0%, at most 20-1%, at most 15-5%, at most 30-3%, etc.) of cells of the pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell- derived, pallial, MGE-type GABAergic interneuron cells) have an exogenous marker. In some embodiments, substantially none of the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE- type GABAergic interneuron cells) has an exogenous marker. [0158] In some embodiments, about 90% or more, e.g., about 95% or more, about 97% or more, about 98% or more, about 98.5% or more, about 99% or more, about 99.5% or more, about 99.7% or more, about 99.8% or more, about 99.9% or more, about 100%, or a percentage in a range defined by any two of the preceding values (e.g., 90-100%, 95-99%, 98-99.9%, 99-100%, etc.) of the cells of the composition are post-mitotic cells. If desired, the percentage of post-mitotic cells in the composition (or a representative portion thereof) can be determined using any suitable option, such as measuring incorporation of a nucleoside analog (e.g., BrdU or EdU), or measuring expression of a proliferation marker (e.g., KI67 and/or ASPM). In some embodiments, about 10% or less, e.g., about 9% or less, about 8% or less, about 7% or less, about 6% or less, about 5% or less, about 4% or less, about 3% or less, about 2% or less, about 1% or less, about 0.5% or less, about 0.1% or less, about 0%, or a percentage in a range defined by any two of the preceding values (e.g., 10-0%, 8-0.1%, 5- 0.1%, 3-0.1%, 1-0.1%, 3-1%, 2-0.1%, 2-0%, etc.) of the cells of the cellular composition express KI67 and/or ASPM. In some embodiments, the cellular composition substantially lacks cells expressing one or more markers for cell cycling selected from: KI67 and ASPM. In some embodiments, 10% or less of the cells of the cellular composition express KI67 and/or ASPM. In some embodiments, 5% or less of the cells of the cellular composition express KI67 and/or ASPM. In some embodiments, 2% or less of the cells of the cellular composition express KI67 and/or ASPM. In some embodiments, 1% or less of the cells of the cellular composition express KI67 and/or ASPM. In some embodiments, 0.5% or less of the cells of the cellular composition express KI67 and/or ASPM. In some embodiments, about 10% or less, e.g., about 9% or less, about 8% or less, about 7% or less, about 6% or less, about 5% or less, about 4% or less, about 3% or less, about 2% or less, about 1% or less, about 0.5% or less, about 0.1% or less, about 0%, or a percentage in a range defined by any two of the preceding values (e.g., 10-0%, 8-0.1%, 5-0.1%, 3-0.1%, 1-0.1%, 3-1%, 2-0.1%, 2- 0%, etc.) of the cells of the cellular composition incorporate a nucleoside analog (e.g., BrdU or EdU). In some embodiments, the cellular composition substantially lacks cells that incorporate a nucleoside analog (e.g., BrdU or EdU). [0159] Any suitable option can be used to increase the percentage of post-mitotic cells in the cellular composition. In some embodiments, an agent that promotes cell cycle exit and differentiation is used to increase the percentage of post-mitotic cells in the cellular composition. A suitable agent that promotes cell cycle exit and differentiation includes, without limitation, an inhibitor of Notch signaling. Suitable inhibitors of Notch signaling include, without limitation, a γ-secretase inhibitor. Suitable γ-secretase inhibitors include, without limitation, DAPT, BMS906024, BMS986115, E-2012, avagacestat, nirogacestat, begacestat, semagacestat, MK-0752, tarenflurbil, RG-4733, PF 3084014, hydrobromid, CultureOne, Compound E, and itanapraced. In some embodiments, the Notch inhibitor is DAPT. In some embodiments, the percentage of post-mitotic cells among the cells of the cellular composition is increased by providing the inhibitor of Notch signaling to the culture for at least about the last week, e.g., the last 1.5 weeks, the last 2 weeks, or the last 2.5 weeks, of differentiation of the pluripotent stem cells into the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells). [0160] In some embodiments, cells of the cellular composition are migratory cells. In some embodiments, about 5% or more, e.g., about 7% or more, about 10% or more, about 15% or more, about 20% or more, about 25% or more, about 30% or more, or a percentage in a range defined by any two of the preceding values (e.g., 5-30%, 7-25%, 10- 30%, 15-25%, etc.) of the cells of the composition are migratory cells, e.g., as determined by an in vitro migration assay. In some embodiments, the proportion of migratory cells among cells of the cellular composition is at least 50%, e.g., 60%, 70%, 80%, 90%, 100%, 120%, 150%, 175%, 200%, 250%, 300% or more, or a percentage in a range defined by any two of the preceding values (e.g., 50-300%, 60-250%, 70-200%, 100-200%, 120-175%, 100-300%, etc.) of the proportion of migratory cells among primary human MGE interneurons, e.g., as determined by an in vitro migration assay. [0161] In some embodiments, the cellular composition comprises GABAergic cells. In some embodiments, the cellular composition comprises GABA-secreting cells. If desired, GABA secretion and/or amount of GABA secretion can be detected using any suitable assay, such as an in vitro GABA release assay. In some embodiments, cells of the cellular composition secrete GABA in an in vitro GABA release assay. In some embodiments, cells of the cellular composition secrete GABA constitutively in an in vitro GABA release assay. In some embodiments, cells of the cellular composition increase GABA secretion upon stimulation, e.g., by potassium chloride, sodium chloride or other salt solution, in an in vitro GABA release assay. [0162] The MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) of the present disclosure are generally derived from pluripotent stem (PS) cells. The MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) can be cells derived from any suitable PS cells. Suitable PS cells include, without limitation, embryonic stem cells (ESC) and induced pluripotent stem cells (iPS cells). In some embodiments, the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) are derived from neural stem cells. In some embodiments, the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells) are obtained through reprogramming or transdifferentiation of cells, e.g., somatic cells, neural cells obtained from the MGE, Cortex, Sub-Cortex, other regions of the brain, or non- neural cells. [0163] The cellular composition for use in the present methods can be obtained using any suitable option. In some embodiments, a cellular composition is obtained by differentiating pluripotent stem cells, e.g., from ESCs or iPS cells, into the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells). In some embodiments, the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) are derived from embryonic stem (ES) cells (e.g., hESCs) or induced pluripotent stem (iPS) cells. In some embodiments, the pluripotent stem cells are expanded before differentiating. In some embodiments, the pluripotent stem cells (e.g., hESCs) are expanded for, for about, or for at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14 days, or at least 3, 4, 5, 6, 7, or 8 weeks, or for a length of time in a range defined by any two of the preceding values (e.g., 1-8 weeks, 1-14 days, 2-10 days, 3-10 days, 3-7 days, etc.). In some embodiments, the pluripotent stem cells (e.g., hESCs) are expanded for about 5 days. In some embodiments, the pluripotent stem cells after expanding retain or substantially retain their pluripotency. In some embodiments, the pluripotent stem cells maintain expression of one or more markers of pluripotent stem cells after expanding. In some embodiments, the pluripotent stem cells exhibit a similar or substantially the same pattern of expression of one or more markers of pluripotent stem cells after expanding compared to the pattern of expression before expanding. In some embodiments, the markers of pluripotent stem cells include one or more of OCT4, NANOG, TRA1-60, and SSEA3/4. In some embodiments, the pluripotent stem cells maintain expression of OCT4, NANOG, TRA1-60, and SSEA3/4 after expanding. In some embodiments, the expanded pluripotent stem cells are OCT4+, NANOG+, TRA1-60+, and SSEA3/4+. Any suitable option for expanding pluripotent stem cells (e.g., hESCs) can be used. In some embodiments, expanding the pluripotent stem cells (e.g., hESCs) includes culturing the cells in the presence of an FGF2 and/or TGFβ signaling activator. In some embodiments, the TGFβ signaling activator includes a SMAD signaling activator. In some embodiments the SMAD signaling activator includes, without limitation, TGFs (e.g., TGFβ3), BMPs (e.g., BMP2, BMP4, BMP8), Activin, Nodal, GDF, and IDE1. In some embodiments, the FGF2 signaling activator includes FGF2. [0164] Any suitable option for differentiating a population of pluripotent stem cells in vitro into a MGE-type neuron lineage (e.g., pallial, MGE-type interneuron lineage) can be used, e.g., as provided herein. In some embodiments, differentiating the population of pluripotent stem cells into the MGE-type neuron lineage includes culturing a population, or a differentiating population, of pluripotent stem cells in the presence of one or more of a sonic hedgehog (shh) signaling activator, a SMAD signaling inhibitor, a wnt signaling inhibitor, a bone morphogenetic protein (BMP) signaling inhibitor, a neural inducing supplement, a Rho- associated kinase (ROCK) signaling inhibitor, MEK signaling inhibitor, CDK signaling inhibitor, and a Notch signaling inhibitor. As used herein, “a differentiating population of pluripotent stem cells” refers to cells that are in the process of developing features of a cell lineage of interest, starting from the pluripotent stem cells. Thus, in some embodiments, cells of the differentiating population may have one or more features characteristic of the pluripotent stem cells and one or more features characteristic of the cell lineage of interest. In some embodiments, a population of pluripotent stem cells that are differentiating into a MGE-type neuron lineage (e.g., pallial, MGE-type interneuron lineage) includes MGE-type progenitor cells. [0165] In some embodiments, differentiating the population of pluripotent stem cells includes supplementing a culture of pluripotent stem cells with one or more of a sonic hedgehog (shh) signaling activator, a SMAD signaling inhibitor, a wnt signaling inhibitor, a bone morphogenetic protein (BMP) signaling inhibitor, a neural inducing supplement, a Rho- associated kinase (ROCK) signaling inhibitor, MEK signaling inhibitor, CDK signaling inhibitor, and a Notch signaling inhibitor. In some embodiments, each of the one or more of a sonic hedgehog (shh) signaling activator, a SMAD signaling inhibitor, a wnt signaling inhibitor, a BMP signaling inhibitor, a neural inducing supplement, a ROCK signaling inhibitor, a MEK signaling inhibitor, a CDK signaling inhibitor, and a Notch signaling inhibitor is present in the culture during a time period that spans at least a portion of the differentiation process. In some embodiments, the culture of pluripotent stem cells is a serum-free culture. In some embodiments, the culture of pluripotent stem cells is a feeder cell-free culture. In some embodiments, the culture of pluripotent stem cells includes a feeder cell, e.g., a human feeder cell. Any suitable feeder cell can be used to culture the pluripotent stem cells in the presence of feeder cells. In some embodiments, the culture of pluripotent stem cells is a xeno-free culture. [0166] In some embodiments, differentiating the population of pluripotent stem cells includes a first time period (e.g., to promote definitive neuroectoderm specification and MGE patterning), a second time period following the first time period (e.g., to promote MGE progenitor expansion and pallial interneuron (or subpallial neuron) commitment), and a third time period following the second time period (e.g., to promote cell cycle exit and differentiation). In some embodiments, differentiating the population of pluripotent stem cells includes culturing the cells in a suitable base medium during the differentiation time course. Any suitable based medium can be used. In some embodiments, the base medium includes without limitation, MEM, DMEM, DMEM-F12, L-15, neurobasal medium, and combinations thereof. In some embodiments, the base medium includes a supplement for neuronal cell culture. Any suitable supplement for neuronal cell culture can be used for differentiating pluripotent stem cells. In some embodiments, the neural inducing supplement is, without limitation, B-27TM (with or without vitamin A), NS21, N2 supplement-B, or an equivalent supplement, and combinations thereof. In some embodiments, the base medium includes amino acids. [0167] In some embodiments, differentiating the population of pluripotent stem cells includes culturing the pluripotent stem cells (e.g., hESCs) in the presence of one or more MGE patterning factors, including a ROCK signaling inhibitor, BMP signaling inhibitor, a TGF-β signaling inhibitor, a wnt signaling inhibitor, and a shh signaling activator during at least a portion of the first time period. In some embodiments, the first time period is, is about, or is at least 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or 21 days, or a length of time in a range defined by any two of the preceding values (e.g., 7-21 days, 10-18 days, 12-16 days, etc.). In some embodiments, the first time period is or is about 2 weeks. In some embodiments, the one or more MGE patterning factors are removed from the culture at the end of the first time period. In some embodiments, each of the MGE patterning factors are added to the culture for any suitable portion of the first time period to promote definitive neuroectoderm specification and MGE patterning. In some embodiments, one or more of the MGE patterning factors are added to the culture at the start of the first time period (e.g., D0 of the differentiation time course). As used herein, the differentiation time course denotes the number of days of the differentiation process starting from the pluripotent stem cells (after and excluding any stem cell expansion stage noted above). In some embodiments, one or more of the MGE patterning factors are added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the first time period (e.g., D1, D2, D3, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14 or later of the differentiation time course). In some embodiments, the cells are cultured in the presence of one or more of the MGE patterning factors for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the first time period. In some embodiments, the cells are cultured in the presence of one or more of the MGE patterning factors between D0-D14, D0- D7, D1-D7, D1-D14, D2-D5, D2-D7, D7-D12, or D7-D14 of the differentiation time course. Any suitable amount of the MGE patterning factors can be used to promote definitive neuroectoderm specification and MGE patterning. In some embodiments, each of the one or more MGE patterning factors is provided in the culture medium independently at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 μM, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 μM, 50 nM-100 μM, 100 nM- 100 μM, or 100 nM-50 μM). [0168] In some embodiments, differentiating the population of pluripotent stem cells further includes culturing the pluripotent stem cells (e.g., hESCs) in the presence of a FGF/VEGF/PDGF inhibitor (e.g., a receptor tyrosine kinase (RTK) inhibitor) during at least a portion of the first time period. Any suitable FGF/VEGF/PDGF inhibitor can be used. In some embodiments, the FGF/VEGF/PDGF inhibitor is, without limitation, SU5402, SU6668, BIBF1120, ZM323881, SU11652, or XL999. [0169] Without being bound by theory, culturing the pluripotent stem cells during the first time period can promote definitive neuroectoderm specification and MGE patterning. For convenience and without limitation, the first time period may be referred to as the “MGE patterning” phase). In some embodiments, the population of cells (e.g., differentiating cells) that have been cultured for the first time period (e.g., MGE patterned cells) is enriched for cells expressing one or more of SOX1, FOXG1, NKX2-1. In some embodiments, the population of cells (e.g., differentiating cells) that have been cultured for the first time period (e.g., MGE patterned cells) is depleted for cells expressing PAX6. In some embodiments, the cells (e.g., differentiating cells) that have been cultured for the first time period (e.g., MGE patterned cells) are SOX1+, FOXG1+, NKX2-1+, and PAX6-. [0170] The shh signaling activator can be any suitable activator of shh signaling. In some embodiments, the shh signaling activator includes, without limitation, shh or a derivative thereof, purmorphamine, SAG smoothened agonist, Hh-Ag1.5, or derivatives and analogs thereof. In some embodiments, the shh signaling activator includes SAG. In some embodiments, the shh signaling activator is added to the culture at the start of the first time period (e.g., D0 of the differentiation time course). In some embodiments, the shh signaling activator is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the first time period (e.g., D1, D2, D3, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14 or later of the differentiation time course). In some embodiments, the cells are cultured in the presence of the shh signaling activator for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1- 14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the first time period. In some embodiments, the cells are cultured in the presence of the shh signaling activator between D0-D14, D0-D7, D1-D7, D1-D14, D2-D5, D2-D7, D7-D12, or D7-D14 of the differentiation time course. Any suitable amount of the shh signaling activator can be used to promote definitive neuroectoderm specification and MGE patterning. In some embodiments, the shh signaling activator is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 μM, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 μM, 50 nM-100 μM, 100 nM-100 μM, or 100 nM-50 μM). In some embodiments, the shh signaling activator is provided in the culture medium at a concentration of or of about 100 nM. [0171] Any suitable inhibitor or activator of SMAD signaling can be used for differentiating pluripotent stem cells. In some embodiments, the SMAD signaling modulator is a SMAD signaling inhibitor, such as, without limitation, TGF-β inhibitor, BMP inhibitor, Activin inhibitor, Nodal inhibitor, or GDF signaling pathway inhibitor. In some embodiments, the SMAD signaling inhibitor includes a TGF-β inhibitor. In some embodiments, the TGF-β inhibitor includes, without limitation, SB431542, Galunisertib, LDN-193189, and/or K02288. In some embodiments, the TGF-β inhibitor includes SB431542. In some embodiments, the TGF-β inhibitor is added to the culture at the start of the first time period (e.g., D0 of the differentiation time course). In some embodiments, the TGF-β inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the first time period (e.g., D1, D2, D3, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14 or later of the differentiation time course). In some embodiments, the cells are cultured in the presence of the TGF-β inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the first time period. In some embodiments, the cells are cultured in the presence of the TGF-β inhibitor between D0- D14, D0-D7, D1-D7, D1-D14, D2-D5, D2-D7, D7-D12, or D7-D14 of the differentiation time course. Any suitable amount of the TGF-β inhibitor can be used to promote definitive neuroectoderm specification and MGE patterning. In some embodiments, the TGF-β inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 μM, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 μM, 50 nM-100 μM, 100 nM-100 μM, or 100 nM-50 μM). In some embodiments, the TGF-β inhibitor is provided in the culture medium at a concentration of or of about 10 μM. [0172] Any suitable inhibitor of BMP signaling can be used to for differentiating pluripotent stem cells. In some embodiments, the BMP signaling inhibitor includes, without limitation, LDN193189, M4K2163, Dorsomorphin, DMH-1, and/or ML 347. In some embodiments, the BMP signaling inhibitor includes LDN193189. In some embodiments, the BMP signaling inhibitor is added to the culture at the start of the first time period (e.g., D0 of the differentiation time course). In some embodiments, the BMP signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the first time period (e.g., D1, D2, D3, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14 or later of the differentiation time course). In some embodiments, the cells are cultured in the presence of the BMP signaling inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the first time period. In some embodiments, the cells are cultured in the presence of the SMAD signaling inhibitor between D0-D14, D0-D7, D1-D7, D1-D14, D2-D5, D2-D7, D7-D12, or D7-D14 of the differentiation time course. Any suitable amount of the BMP signaling inhibitor can be used to promote definitive neuroectoderm specification and MGE patterning. In some embodiments, the BMP signaling inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 μM, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 μM, 50 nM-100 μM, 100 nM-100 μM, or 100 nM-50 μM). In some embodiments, the BMP signaling inhibitor is provided in the culture medium at a concentration of or of about 10 μM. [0173] Any suitable inhibitor of wnt signaling can be used for differentiating pluripotent stem cells. In some embodiments, the wnt signaling inhibitor includes, without limitation, soluble frizzled polypeptides comprising the wnt binding domains; soluble frizzled related polypeptides; wnt specific antibodies; frizzled specific antibodies; and other molecules capable of blocking extracellular wnt signaling; Dkk gene family such as, but not limited to, Dkk-1, Dkk-2, Dkk-3, and Dkk-4, and the Dkk-3 related protein Soggy (Sgy); Wise; or a small molecule inhibitor, such as, but not limited to CKI-7, IWP analogs, IWR analogs, XAV939, 53AH, Wnt-C59. In some embodiments, the wnt signaling inhibitor includes XAV939. In some embodiments, the wnt signaling inhibitor is added to the culture at the start of the first time period (e.g., D0 of the differentiation time course). In some embodiments, the wnt signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the first time period (e.g., D1, D2, D3, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14 or later of the differentiation time course). In some embodiments, the cells are cultured in the presence of the wnt signaling inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the first time period. In some embodiments, the cells are cultured in the presence of the wnt signaling inhibitor between D0-D14, D0-D7, D1-D7, D1-D14, D2-D5, D2-D7, D7- D12, or D7-D14 of the differentiation time course. Any suitable amount of the wnt signaling inhibitor can be used to promote definitive neuroectoderm specification and MGE patterning. In some embodiments, the wnt signaling inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 μM, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 μM, 50 nM-100 μM, 100 nM- 100 μM, or 100 nM-50 μM). In some embodiments, the wnt signaling inhibitor is provided in the culture medium at a concentration of or of about 10 μM. [0174] Any suitable inhibitor of ROCK signaling can be used for differentiating pluripotent stem cells. In some embodiments, the ROCK signaling inhibitor includes, without limitation, Y27623, thiazovivin, fasudil, ripasudil, or KD025. In some embodiments, the ROCK signaling inhibitor includes Y27623. In some embodiments, the ROCK signaling inhibitor is added to the culture at the start of the first time period (e.g., D0 of the differentiation time course). In some embodiments, the ROCK signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the first time period (e.g., D1, D2, D3, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14 or later of the differentiation time course). In some embodiments, the cells are cultured in the presence of the ROCK signaling inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the first time period. In some embodiments, the cells are cultured in the presence of the ROCK signaling inhibitor between D0-D14, D0-D7, D1-D7, D1-D14, D2-D5, D2-D7, D7-D12, or D7-D14 of the differentiation time course. Any suitable amount of the ROCK signaling inhibitor can be used to promote definitive neuroectoderm specification and MGE patterning. In some embodiments, the ROCK signaling inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 μM, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 μM, 50 nM-100 μM, 100 nM-100 μM, or 100 nM-50 μM). In some embodiments, the ROCK signaling inhibitor is provided in the culture medium at a concentration of or of about 10 μM. [0175] In some embodiments, differentiating the population of pluripotent stem cells includes further culturing the cells (e.g., differentiating cells) that have been cultured for the first time period (e.g., MGE patterned cells), in the presence of a MEK signaling inhibitor during at least a portion of the second time period. In some embodiments, the second time period is, is about, or is at least 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28 days, or a length of time in a range defined by any two of the preceding values (e.g., 7-28 days, 7-21 days, 10-18 days, 12-16 days, etc.). In some embodiments, the second time period is or is about 2 weeks. In some embodiments, the cells (e.g., differentiating cells) are cultured without the signaling inhibitors (e.g., MEK signaling inhibitor) or activators as described herein during a portion (e.g., at the start) of the second time period. In some embodiments, the cells (e.g., differentiating cells) are cultured without the MEK signaling inhibitor during a portion (e.g., at the start) of the second time period. In some embodiments, the MEK signaling inhibitor is removed from the culture at the end of the second time period. In some embodiments, culturing the cells (e.g., differentiating cells) during the second time period can promote MGE progenitor expansion and pallial interneuron commitment. For convenience and without limitation, the second time period may be referred to as the “expansion and commitment” phase). In some embodiments, the population of cells (e.g., differentiating cells) that have been cultured for the second time period (e.g., expanded and committed cells) is enriched for cells expressing LHX8 and/or LHX6. In some embodiments, the population of cells (e.g., differentiating cells) that have been cultured for the second time period (e.g., expanded and committed cells) is depleted for cells expressing high levels of NKX2-1, e.g., NKX2-1 expressed at levels expressed by MGE precursor cells. In some embodiments, the cells (e.g., differentiating cells) that have been cultured for the second time period (e.g., expanded and committed cells) are LHX8+, and have declining NKX2-1 expression and increasing LHX6 expression. In some embodiments, NKX2.1 continues to be expressed. In some embodiments, culturing the cells (e.g., differentiating cells) during the second time period can promote MGE progenitor expansion and subpallial neuron commitment (e.g., by omitting the MEK signaling inhibitor). [0176] Any suitable inhibitor of MEK signaling can be used for differentiating pluripotent stem cells into a pallial interneuron lineage. In some embodiments, the MEK signaling inhibitor includes, without limitation, PD0325901. In some embodiments, the MEK signaling inhibitor includes PD0325901. In some embodiments, the MEK signaling inhibitor is added to the culture at the start of the second time period (e.g., around D14 of the differentiation time course). In some embodiments, the MEK signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the second time period (e.g., D14, D15, D16, D17, D18, D19, D20, D21, D22, D23, D24, D25, D26, D27, D28 or later of the differentiation time course). In some embodiments, the cells are cultured in the presence of the MEK signaling inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the second time period. In some embodiments, the cells are cultured in the presence of the MEK signaling inhibitor between D14-D28, D14-D21, D15-D21, D15-D28, or D21-D28 of the differentiation time course. Any suitable amount of the MEK signaling inhibitor can be used to promote MGE progenitor expansion and pallial interneuron commitment. In some embodiments, the MEK signaling inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 2, 5, 10, 20, 50, 100, or 200 μM, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 μM, 50 nM-100 μM, 100 nM- 100 μM, or 100 nM-50 μM). In some embodiments, the MEK signaling inhibitor is provided in the culture medium at a concentration of, or of about 2 μM. [0177] In some embodiments, differentiating the population of pluripotent stem cells includes further culturing the cells (e.g., differentiating cells) that have been cultured for the second time period (e.g., expanded and committed cells), in the presence of one or more cell cycle exit and differentiation factors, including a MEK signaling inhibitor, a CDK signaling inhibitor, and a Notch signaling inhibitor during at least a portion of the third time period. In some embodiments, the third time period is, is about, or is at least 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or 21 days, or a length of time in a range defined by any two of the preceding values (e.g., 7-21 days, 10-18 days, 12-16 days, etc.). In some embodiments, the third time period is or is about 2 weeks. In some embodiments, the one or more cell cycle exit and differentiation factors are removed from the culture at the end of the third time period. In some embodiments, each of the cell cycle exit and differentiation factors are added to the culture for any suitable portion of the third time period to promote cell cycle exit and differentiation. In some embodiments, one or more of the cell cycle exit and differentiation factors are added to the culture at the start of the third time period (e.g., around D28 of the differentiation time course). In some embodiments, one or more of the cell cycle exit and differentiation factors are added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the third time period (e.g., D28, D29, D30, D31, D32, D33, D34, D35, D36, D37, D38, D39, D40 or later of the differentiation time course). In some embodiments, the cells are cultured in the presence of one or more of the cell cycle exit and differentiation factors for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the third time period. In some embodiments, the cells are cultured in the presence of one or more of the cell cycle exit and differentiation factors between D28-D42, D28-D35, D29-D35, D29-D42, D30-D33, D30- D35, D35-D42, or D35-D40 of the differentiation time course. Any suitable amount of the cell cycle exit and differentiation factors can be used to promote cell cycle exit and differentiation. In some embodiments, each of the one or more cell cycle exit and differentiation factors is provided in the culture medium independently at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 μM, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 μM, 50 nM-100 μM, 100 nM-100 μM, or 100 nM-50 μM). [0178] In some embodiments, culturing the cells (e.g., differentiating cells) during the third time period promotes cell cycle exit and differentiation. For convenience and without limitation, the third time period may be referred to as “cell cycle exit” phase). For convenience and without limitation, the differentiated cells after culturing in the first, second and third time periods may be referred to as end-of-process (EOP) neurons. In some embodiments, the population of EOP neurons is enriched for cells expressing one or more of LHX6, GAD1, and ERBB4/CXCR4. In some embodiments, obtaining the cellular composition for use in the present methods includes enriching the differentiated cells for cells expressing one or more of LHX6, GAD1, and ERBB4/CXCR4/CXCR7. In some embodiments, enriching the differentiated cells includes using a binding moiety (e.g., antibody) that specifically binds to ERBB4 or CXCR4 or CXCR7, e.g., using FACS or MACS. In some embodiments, the population of EOP neurons is depleted for cells expressing LHX8 and/or NKX2-1. In some embodiments, the EOP neurons are LHX6+, GAD1+, ERBB4+/CXCR4+/CXCR7+, LHX8- and NKX2-1-. [0179] Any suitable agent that inhibits Notch signaling can be used during the differentiation process for obtaining the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells). In some embodiments, the Notch signaling inhibitor includes, a γ-secretase inhibitor. In some embodiments, the Notch signaling inhibitor includes, without limitation, DAPT, BMS906024, BMS986115, E-2012, avagacestat, nirogacestat, begacestat, semagacestat, MK-0752, tarenflurbil, RG-4733, itanapraced, PF3084014, and/or Culture One. In some embodiments, the Notch signaling inhibitor is added to the culture at the start of the third time period (e.g., around D28 of the differentiation time course). In some embodiments, the Notch signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the third time period (e.g., D28, D29, D30, D31, D32, D33, D34, D35, D36, D37, D38, D39, D40 or later of the differentiation time course). In some embodiments, the cells are cultured in the presence of the Notch signaling inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the third time period. In some embodiments, the cells are cultured in the presence of the Notch signaling inhibitor between D28-D42, D28-D35, D29-D35, D29-D42, D30-D33, D30-D35, D35-D42, or D35-D40 of the differentiation time course. Any suitable amount of the Notch signaling inhibitor can be used to promote cell cycle exit and differentiation. In some embodiments, the Notch signaling inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 μM, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 μM, 50 nM-100 μM, 100 nM-100 μM, or 100 nM-50 μM). In some embodiments, the Notch signaling inhibitor is provided in the culture medium at a concentration of or of about 10 μM. [0180] In some embodiments, differentiating the population of pluripotent stem cells into the MGE-type neuron lineage (e.g., pallial, MGE-type interneuron lineage) includes culturing the differentiating population of pluripotent stem cells in the presence of a NOTCH signaling inhibitor for a time period after obtaining MGE-like progenitor cells. In some embodiments, differentiating pluripotent stem cells to obtain the pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells includes culturing MGE-like progenitor cells derived from pluripotent stem cells in the presence of a Notch signaling inhibitor. In some embodiments, differentiating pluripotent stem cells includes culturing the population of pluripotent stem cells in the presence of a sonic hedgehog (shh) signaling activator, a TGFbeta signaling inhibitor, and a wnt signaling inhibitor to obtain MGE-like progenitor cells, and further culturing the MGE-like progenitor cells in the presence of a Notch signaling inhibitor, to obtain pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells. [0181] Any suitable inhibitor of CDK signaling can be used for differentiating pluripotent stem cells. In some embodiments, the CDK signaling inhibitor includes, without limitation, PD0332991, ribociclib, abemaciclib, flavopiridol, or AT7519. In some embodiments, the CDK signaling inhibitor includes PD0332991. In some embodiments, the CDK signaling inhibitor is added to the culture at the start of the third time period (e.g., around D28 of the differentiation time course). In some embodiments, the CDK signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the third time period (e.g., D28, D29, D30, D31, D32, D33, D34, D35, D36, D37, D38, D39, D40 or later of the differentiation time course). In some embodiments, the cells are cultured in the presence of the CDK signaling inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the third time period. In some embodiments, the cells are cultured in the presence of the CDK signaling inhibitor between D28-D42, D28-D35, D29-D35, D29-D42, D30-D33, D30-D35, D35-D42, or D35-D40 of the differentiation time course. Any suitable amount of the CDK signaling inhibitor can be used to promote cell cycle exit and differentiation. In some embodiments, the CDK signaling inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 μM, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 μM, 50 nM-100 μM, 100 nM-100 μM, or 100 nM-50 μM). In some embodiments, the CDK signaling inhibitor is provided in the culture medium at a concentration of or of about 10 μM. [0182] Any suitable inhibitor of MEK signaling can be used for differentiating pluripotent stem cells. In some embodiments, the MEK signaling inhibitor includes, without limitation, PD0325901. In some embodiments, the MEK signaling inhibitor includes PD0325901. In some embodiments, the MEK signaling inhibitor is added to the culture at the start of the third time period (e.g., around D28 of the differentiation time course). In some embodiments, the MEK signaling inhibitor is not added to the culture during the second time period, and is added at the start of the third time period (e.g., at D28 of the differentiation time course). In some embodiments, the MEK signaling inhibitor is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the third time period (e.g., D28, D29, D30, D31, D32, D33, D34, D35, D36, D37, D38, D39, D40 or later of the differentiation time course). In some embodiments, the cells are cultured in the presence of the MEK signaling inhibitor for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the third time period. In some embodiments, the cells are cultured in the presence of the MEK signaling inhibitor between D28-D42, D28-D35, D29-D35, D29-D42, D30-D33, D30-D35, D35-D42, or D35-D40 of the differentiation time course. Any suitable amount of the MEK signaling inhibitor can be used to promote cell cycle exit and differentiation. In some embodiments, the MEK signaling inhibitor is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 2, 5, 10, 20, 50, 100, or 200 μM, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 μM, 50 nM-100 μM, 100 nM-100 μM, or 100 nM-50 μM). In some embodiments, the MEK signaling inhibitor is provided in the culture medium at a concentration of or of about 2 μM. [0183] In some embodiments, differentiating the population of pluripotent stem cells includes further culturing the cells (e.g., differentiating cells) that have been cultured for the second time period (e.g., expanded and committed cells), in the presence of a wnt signaling activator (e.g., a wnt, a GSK3 inhibitor, beta-catenin activator, etc.) during at least a portion of the third time period. Any suitable wnt signaling activator can be used. In some embodiments, the wnt signaling activator is, without limitation, BIO(6-bromoindirubin-3'- oxime), LY2090314, SB-216763, CHIR99021, WAY 262611, LP 922056, or DCA. In some embodiments, the wnt signaling activator is added to the culture at the start of the third time period (e.g., around D28 of the differentiation time course). In some embodiments, the wnt signaling activator is added to the culture 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days after the start of the third time period (e.g., D28, D29, D30, D31, D32, D33, D34, D35, D36, D37, D38, D39, D40 or later of the differentiation time course). In some embodiments, the cells are cultured in the presence of the wnt signaling activator for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or more days, or a length of time in a range defined by any two of the preceding values (e.g., 1-14 days, 2-10 days, 2-7 days, 4-10 days, 7-14 days, etc.), during the third time period. In some embodiments, the cells are cultured in the presence of the wnt signaling activator between D28-D42, D28-D35, D29-D35, D29-D42, D30-D33, D30-D35, D35-D42, or D35-D40 of the differentiation time course. Any suitable amount of the wnt signaling activator can be used to promote cell cycle exit and differentiation. In some embodiments, the wnt signaling activator is provided in the culture medium at a concentration of, of about, or of at least 1, 5, 10, 20, 50, 100, 150, 200, 250, 500, or 750 nM, or of, of about, or of at least 1, 5, 10, 20, 50, 100, or 200 μM, or a concentration in a range defined by any two of the preceding values (e.g., 1 nM-200 μM, 50 nM-100 μM, 100 nM- 100 μM, or 100 nM-50 μM). [0184] In some embodiments, deriving the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) does not include sorting the differentiating population of pluripotent stem cells, e.g., using FACS or MACS, based on expression of an exogenous marker for MGE-type progenitors. In some embodiment, the pluripotent stem cells do not have or express an exogenous marker for MGE-type lineage cells (e.g., a transgenically-expressed marker for MGE-type progenitors or GABAergic cortical interneurons). In some embodiments, the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) are derived from pluripotent cells without using sorting techniques, e.g., FACS or MACS, based on expression of an exogenous MGE-type progenitor marker. [0185] In some embodiments, deriving the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) includes enriching for cells expressing one or more MGE-type neuron-specific cell-surface markers (e.g., one or more pallial, MGE-type interneuron-specific cell-surface markers). Any suitable option can be used to enrich the differentiating population for cells based on expression of one or more MGE-type neuron-specific cell-surface markers (e.g., one or more pallial, MGE- type interneuron-specific cell-surface markers). Suitable options include, without limitation, flow cytometry, FACS, MACS, etc. In some embodiments, deriving the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) does not include sorting for cells expressing one or more MGE-type interneuron- specific cell-surface markers. In some embodiments, the population of differentiated cells (e.g., MGE-type GABAergic interneuron cells) includes a mix of pallial, MGE-type GABAergic interneuron cells (e.g., cells expressing markers for the pallial, MGE-type GABAergic interneuron lineage) and subpallial, MGE-type GABAergic neuron cells (e.g., cells expressing markers for the subpallial, MGE-type GABAergic neuron lineage), without sorting. In some embodiments, differentiating the pluripotent stem cells according to options described herein generates, without sorting, a population of MGE-type GABAergic neuron cells that is or is about 80%, 85%, or 90%, or a percentage in a range defined by any two of the preceding values (e.g., 80-90%, 85-90%, 80-85%) of the pallial interneuron lineage. In some embodiments, differentiating the pluripotent stem cells according to options described herein generates, without sorting, a population of MGE-type GABAergic neuron cells that is or is about 10%, 15%, or 20%, or a percentage in a range defined by any two of the preceding values (e.g., 10-20%, 15-20%, 10-15%) of the subpallial neuron lineage. [0186] In some embodiments, differentiating pluripotent stem cells to obtain subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cells is carried out using any suitable option. In some embodiments, subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cells are obtained by differentiating pluripotent stem cells as described herein, and enriching for LHX6+, ERBB4-, LHX8+ and/or NKX2.1+, GAD1+ cells. In some embodiments, subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cells are obtained by differentiating pluripotent stem cells as described herein, but omitting the MEK inhibitor during the differentiation process. In some embodiments, subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cells are enriched by sorting for cells, for example, by FACS or MACS. In some embodiments, subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cells are enriched by sorting for cells using binding agents to one or more surface markers (e.g., NRP2+) expressed on cells of the subpallial lineage. In some embodiments, subpallial, MGE-type inhibitory (e.g., GABAergic) neuron cells are enriched by depleting non-pallial cells using binding agents to one or more surface markers (e.g., ERBB4+) not expressed on cells of the subpallial lineage. In some embodiments, the subpallial, MGE-type GABAergic neuron cells include interneurons and/or projection neurons. [0187] In some embodiments, the method includes cryopreserving the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) after deriving the cells from the pluripotent stem cells. Any suitable option for cryopreserving mammalian cells can be used. In some embodiments, the method includes thawing a cryopreserved cellular composition that includes the MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) before administering the cells. [0188] In some embodiments, the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) are autologous to the subject. In some embodiments, the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) are heterologous to the subject. In some embodiments, the interneurons, precursors, and/or pluripotent stem cells of the present disclosure, are genetically modified. In some embodiments, the interneurons, precursors, and/or pluripotent stem cells of the present disclosure include one or more mutations (e.g., nucleic acid substitutions, deletions, insertions, chromosomal rearrangements, etc.) relative to a native genome. In some embodiments, the pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) are genetically modified. In some embodiments, the genetic modification alters (e.g., reduces, abolishes, enhances, etc.) an expression and/or function of a gene product (e.g., protein) regulated or encoded by the modified genetic locus. Any suitable genetically-encoded function can be altered through genetic modification of the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells (and/or precursor thereof). In some embodiments, the pluripotent stem cell- derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) are genetically modified to reduce an immunological response against the administered cellular composition by the subject. Any suitable gene immune- activating genes can be mutated to reduce or abolish activity, or can be knocked out, and/or any suitable genetic modification that activates expression or activity of immune-inhibiting genes can be present in the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells. In some embodiments, the pluripotent stem cell-derived, pallial, MGE- type GABAergic interneuron cells are genetically modified to reduce or abolish expression of one or more of: B2M, a HLA class I gene, and/or a HLA class II gene. In some embodiments, the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells are genetically modified to knock out one or more of: B2M, a HLA class I gene, and/or a HLA class II gene. SYSTEMS [0189] Also provided is a delivery system for transplanting cells, such as but not limited to pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells) as provided herein, into a tissue, such as but not limited to one or more regions of the brain, as provided herein. The system can include a delivery cannula (or catheter, or similar device) that includes: a proximal portion comprising a cellular liquid composition having cells (e.g., pluripotent stem cell-derived, MGE-type inhibitory (e.g., GABAergic) neuron cells (e.g., pallial, MGE-type GABAergic interneuron cells), or NRTX-1001) at a concentration of about 1 x 105 cells/μL or greater; and a distal portion comprising a liquid chase vehicle, wherein the cellular liquid composition is stably held in the proximal portion by the liquid chase vehicle; and a displacement device (e.g., a syringe with optional syringe pump) connected to the distal end of the cannula and configured to cause the liquid chase vehicle to displace the cellular liquid composition to thereby expel the cellular liquid composition from the proximal end of the cannula. In some embodiments, a stylet that traverses the inner lumen of the cannula is used to displace the cellular liquid composition, with or without the liquid chase vehicle, to thereby expel the cellular liquid composition from the proximal end of the cannula. The cellular liquid composition can include cells at any suitable concentration, as described herein, such as at about 1 x 105 cells/μL or greater (e.g., about 0.5 x 106 cells per microliter to about 1.5 x 106 cells per microliter, about 0.9 x 106 cells per microliter to about 1.2 x 106 cells per microliter, or about 1 x 106 cells per microliter). In some embodiments, the cellular liquid composition includes cells at a concentration of about 1 x 105 cells/μL or greater, and up to about 2 x 106 cells per microliter. In some embodiments, the cellular liquid composition includes cells at a concentration of, of about, or of at least 0.1 x 106, 0.2 x 106, 0.3 x 106, 0.4 x 106, 0.5 x 106, 0.6 x 106, 0.7 x 106, 0.8 x 106, 0.9 x 106, 1 x 106, 1.1 x 106, 1.2 x 106, 1.3 x 106, 1.4 x 106, 1.5 x 106, 1.6 x 106, 1.7 x 106, 1.8 x 106, 1.9 x 106, or 2 x 106 cells per microliter, or at a concentration in a range defined by any two of the preceding values (e.g., 0.1 x 106 – 2 x 106 cells per microliter, 0.5 x 106 – 2 x 106 cells per microliter, 0.6 x 106 – 1.2 x 106 cells per microliter, 0.6 x 106 – 1 x 106 cells per microliter, 0.8 x 106 – 1.2 x 106 cells per microliter, etc.). In some embodiments, the cellular liquid composition includes cells at a concentration of about 0.6 x 106 cells per microliter to about 1.2 x 106 cells per microliter. In some embodiments, the system includes a pump (e.g., syringe pump) connected to the displacement device. [0190] Provided herein is a delivery system for transplanting cells. The system can include a delivery cannula containing a cellular liquid composition comprising cells at a concentration of about 1 x 105 cells/μL or greater; and a displacement device connected to a distal end of the cannula and configured to displace the cellular liquid composition in the cannula to thereby expel the cellular liquid composition from the proximal end of the cannula. In some embodiments, the displacement device includes a stylet configured to traverse the inner lumen of the delivery cannula to thereby expel the cellular liquid composition from the proximal end of the cannula. [0191] In some embodiments, the system includes a monitoring device configured to monitor the delivery site in the subject’s brain during administration of the cellular composition. In some embodiments, the monitoring device is configured to detect the position of the proximal end of the cannula at a site of delivery in a subject. Any suitable monitoring device can be used. In some embodiments, the monitoring device includes, without limitation, a CT scanner, MRI scanner, PET scanner, or a SPECT scanner. [0192] The system of the present disclosure can be used to carry out any of the methods of treating seizure activity as described herein. [0193] Further non-limiting embodiments of the present disclosure are provided in the following numbered arrangements. 1. A method of treating seizure activity, comprising: identifying a subject in need of treating seizure activity; and administering to the subject a therapeutically effective amount of a cellular composition comprising pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1, and wherein a frequency of seizures is reduced after the administering, thereby treating the seizure activity. 2. The method of arrangement 1, wherein the subject has a focal epilepsy. 3. The method of arrangement 1, wherein the subject has a chronic seizure activity. 4. The method of any one of the preceding arrangements, wherein the subject has mesial temporal sclerosis. 5. The method of arrangement 4, wherein the mesial temporal sclerosis is reduced after the administering 6. The method of any one of the preceding arrangements, wherein the subject has an epileptogenic lesion in the brain. 7. The method of arrangement 6, wherein the epileptogenic lesion is reduced after the administering. 8. The method of any one of the preceding arrangements, wherein at most 50% of the cells of the composition express NKX2-1. 9. The method of any one of the preceding arrangements, wherein at most 40% of the cells of the composition express LHX8. 10. The method of any one of the preceding arrangements, wherein the at least 50% of the cells of the composition further express at least one of MAF and MAFB. 11. The method of any one of the preceding arrangements, wherein the therapeutically effective amount comprises about 5 x 104 cells or more. 12. The method of arrangement 11, wherein the therapeutically effective amount comprises between about 5 x 104 to about 1 x 1012 cells. 13. The method of any one of the preceding arrangements, wherein the therapeutically effective amount of the cellular composition is administered at a concentration of about 1 x 105 cells/μL or greater. 14. The method of any one of the preceding arrangements, wherein the cellular composition comprises sodium chloride at 100-600 mM. 15. The method of any one of the preceding arrangements, wherein the cellular composition has an osmolality of at least 200 mOsm/kg. 16. The method of any one of the preceding arrangements, wherein at most 40% of the cells express an MGE progenitor cell marker or a non-pallial MGE-type neural cell marker. 17. The method of any one of the preceding arrangements, wherein at most 10% of the cells of the composition express KI67. 18. The method of any one of the preceding arrangements, wherein at most 10% of the cells of the composition express OLIG2. 19. The method of any one of the preceding arrangements, wherein cells of the composition are GABA-secreting cells. 20. The method of any one of the preceding arrangements, wherein cells of the composition are migratory cells. 21. The method of any one of the preceding arrangements, wherein at least 50% of the cells of the composition are pallial MGE-type inhibitory (e.g., GABAergic) interneuron cells. 22. The method of any one of the preceding arrangements, wherein the subject has temporal lobe epilepsy (TLE). 23. The method of arrangement 22, wherein the TLE is drug-resistant TLE. 24. The method of any one of the preceding arrangements, wherein the subject suffers from a neocortical onset focal epilepsy. 25. The method of any one of the preceding arrangements, wherein the subject suffers from focal seizure activity. 26. The method of any one of the preceding arrangements, comprising administering the therapeutically effective amount of the cellular composition to the subject’s brain. 27. The method of any one of the preceding arrangements, further comprising performing one or more of computed tomography (CT) scan, magnetic resonance imaging (MRI), MR spectroscopy (MRS), functional MRI (fMRI), electroencephalography (EEG), intracranial EEG, positron emission tomography (PET), and single photon emission computed tomography (SPECT) on the subject. 28. The method of any one of the preceding arrangements, further comprising monitoring brain activity in the subject. 29. The method of any one of the preceding arrangements, further comprising identifying a mesial temporal sclerosis in the subject, or one or more lesions in the brain. 30. The method of arrangement 29, wherein identifying the mesial temporal sclerosis in the subject or the one or more lesions comprises performing one or more of a CT scan, MRI, MRS, EEG, PET, SPECT, or fMRI. 31. The method of any one of the preceding arrangements, wherein the frequency of seizures is reduced by about 50% or more after the administering. 32. The method of any one of the preceding arrangements, further comprising performing one or more neurocognitive assessments of the subject. 33. The method of any one of the preceding arrangements, wherein the cellular composition is a thawed cellular composition. 34. The method of arrangement 33, comprising holding the thawed cellular composition for up to about 5 days before administering to the subject. 35. The method of arrangement 33 or 34, comprising holding the thawed cellular composition at an ambient temperature of 4-25°C, or 2-18°C, or at room temperature, before administering to the subject. 36. The method of any one of the preceding arrangements, further comprising thawing a cryopreserved cellular composition comprising the pluripotent stem cell-derived, pallial, MGE-type, inhibitory (e.g., GABAergic) interneuron cells before administering. 37. The method of any one of the preceding arrangements, wherein the administering comprises administering the cellular composition as one or more deposits in the subject’s brain. 38. The method of arrangement 37, wherein the therapeutically effective amount of the cellular composition is delivered in a volume of about 50 μL or less per deposit. 39. The method of any one of the preceding arrangements, wherein the administering comprises administering the cellular composition to one or more sites in the temporal lobe, optionally wherein the one or more sites in the temporal lobe include the hippocampus, cortex, and/or amygdala, optionally wherein the one or more sites in the temporal lobe include the hippocampus, subiculum, entorhinal cortex, and/or parahippocampal gyrus. 40. The method of any one of the preceding arrangements, wherein the cells are human cells. 41. The method of any one of the preceding arrangements, wherein the subject is a human subject. 42. The method of any one of the preceding arrangements, further comprising administering an immunosuppressant before and/or after administering the therapeutically effective amount of the cellular composition. 43. The method of any one of the preceding arrangements, wherein the seizure activity is due to a traumatic brain injury, stroke, tumor, focal cortical dysplasia, tuberous sclerosis, developmental disorder, or a neurological disorder. 44. The method of any one of the preceding arrangements, wherein the subject suffers from epileptic seizure-like discharges in the brain associated with Alzheimer’s disease, focal cortical dysplasia (FCD), or amnesic mild cognitive impairment (aMCI). 45. The method of any one of the preceding arrangements, further comprising monitoring a therapeutic effect of administering the cellular composition in the subject. 46. The method of arrangement 45, comprising non-invasively monitoring the therapeutic effect using one or more biomarkers of seizure activity. 47. The method of arrangement 46, wherein the one or more biomarkers comprises N-acetylaspartate (NAA), myoinositol, glutamate, GABA, volume, edema, blood flow, oxygen metabolism, and glucose. 48. The method of any one of arrangements 45-47, comprising using EEG, imaging, and/or one or more blood-based biomarkers to monitor the therapeutic effect. 49. A method of treating seizure activity, comprising: identifying a subject in need of treating seizure activity; and intracranially administering to the subject a cellular composition comprising: about 5 x 104 to about 1 x 1012 pluripotent stem cell-derived, pallial, MGE- type GABAergic interneuron cells at a concentration in a range of about 1 x 105 to about 4 x 106 cells/μL, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1, wherein 90% or more of the cells of the composition are post-mitotic cells; a poloxamer at 0.1-1%, v/v; and sodium chloride at 100-600 mM. 50. Use of a cellular composition for the treatment of seizure activity in a subject, the composition comprising pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and at least one of MAF and MAFB, optionally wherein at least 90% of the cells are post-mitotic cells. 51. A cellular composition of pluripotent stem cell-derived, pallial MGE-type inhibitory (e.g., GABAergic) interneuron cells for the preparation of a medicament for treatment of seizure activity in a subject, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1. 52. A therapeutic composition of pluripotent stem cell-derived, pallial MGE-type inhibitory (e.g., GABAergic) interneuron cells for the treatment of focal onset seizure, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1. 53. A therapeutic composition comprising: a poloxamer; and pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells at a concentration of about 1 x 105 cells/μL or greater. 54. A method of preparing a therapeutic composition for administering to a subject, comprising: providing pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells; and preparing a cellular composition comprising: a poloxamer; and the pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells at a concentration of about 1 x 105 cells/μL or greater. 55. A delivery system for transplanting cells into a tissue, comprising: a delivery cannula comprising: a proximal portion comprising a cellular liquid composition comprising cells at a concentration of about 1 x 105 cells/μL or greater; and a distal portion comprising a cell-free liquid chase vehicle, wherein the cellular liquid composition is stably held in the proximal portion by the liquid chase vehicle; and a displacement device connected to a distal end of the cannula and configured to cause the liquid chase vehicle to displace the cellular liquid composition to thereby expel the cellular liquid composition from a proximal end of the cannula. 56. A delivery system for transplanting cells into a tissue, comprising: a delivery cannula comprising a cellular liquid composition comprising cells at a concentration of about 1 x 105 cells/μL or greater; and a displacement device connected to a distal end of the cannula and configured to displace the cellular liquid composition in the cannula to thereby expel the cellular liquid composition from a proximal end of the cannula. 57. The delivery system of arrangement 55 or 56, wherein the displacement device comprises a syringe, or a stylet traversing the inner lumen of the delivery cannula. 58. The delivery system of any one of arrangements 55-57, further comprising a pump connected to the displacement device. 59. The delivery system of any one of arrangements 55-58, wherein the cellular liquid composition comprises a contrast agent. 60. The delivery system of arrangement 59, wherein the contrast agent comprises an MRI contrast agent. 61. The delivery system of arrangement 59 or 60, wherein the contrast agent comprises a gadolinium-based contrast agent. 62. The delivery system of any one of arrangements 55-59, further comprising a monitoring device configured to detect the position of the proximal end of the cannula at a site of delivery in a subject. 63. The delivery system of arrangement 62, wherein the monitoring device comprises a CT scanner, MRI scanner, PET scanner, or a SPECT scanner. 64. The delivery system of any one of arrangements 55-63, wherein the cells are neuron cells. 65. The delivery system of arrangement 64, wherein the cells comprise pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells. 66. A method of treating seizure activity, comprising: identifying a subject in need of treating seizure activity; and administering to the subject a therapeutically effective amount of a cellular liquid composition comprising pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells using the system of any one of arrangements 55-65, wherein the cellular liquid composition comprises the pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells. 67. The method of arrangement 66, comprising detecting the position of the delivery cannula in the subject’s brain during the administering. 68. The method of arrangement 66 or 67, wherein the detecting comprises using MRI to visualize the delivery cannula in the subject’s brain. 69. The method, therapeutic composition, or delivery system of any one of the preceding arrangements, wherein the cellular composition or the cellular liquid composition comprises NRTX-1001. 70. The method, therapeutic composition, or delivery system of any one of the preceding arrangements, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1, and wherein at least 90% of the cells are post-mitotic cells. 71. The method, therapeutic composition, or delivery system of any one of the preceding arrangements, wherein at least 50% of the cells persisting in the subject retain a pallial, MGE-type GABAergic interneuron cell fate at least 6 months after administration. 72. The method, therapeutic composition, or delivery system of arrangement 71, wherein the cells persisting in the subject and that retain the pallial, MGE-type GABAergic interneuron cell fate express one or more of GAD1, GAD2, LHX6, SOX6, NXPH1, ERBB4, SST, NPY, MEF2c, and ARX. 73. The method, therapeutic composition, or delivery system of any one of the preceding arrangements, wherein the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells are genetically modified. 74. The method, therapeutic composition, or delivery system of arrangement 73, wherein the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells are genetically modified to reduce an immunological response against the administered cellular composition by the subject, optionally wherein the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells comprises: a mutation in one or more immune-activating genes that reduces or abolishes expression or activity thereof; and/or a genetic modification that activates expression or activity of one or more immune-inhibiting genes. 75. The method, therapeutic composition, or delivery system of arrangement 74, wherein pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells are genetically modified to reduce or abolish expression of one or more of: B2M, a HLA class I gene, and/or a HLA class II gene. EXAMPLES Example 1 [0194] This non-limiting example introduces Examples 2-9. [0195] Epilepsy, one of the most common central nervous system disorders, is characterized by abnormal, excessive, and/or synchronous electrical activity in the brain. Imbalanced neural excitatory and inhibitory activity results in hyperactive neuronal networks that precipitate and propagate seizures. Consequently, anti-seizure drugs (ASDs) have been designed to decrease neuronal activity. However, one-third of individuals with epilepsy have drug-resistant seizures. ASDs that potentiate the inhibitory neurotransmitter GABA are effective acute seizure suppressants. Still, these drugs are typically not first-line medications for chronic epilepsy due to systemic and neurotoxic side effects, tolerance, and addiction. There are few effective options for people living with drug-resistant chronic epilepsy. Surgical resection or laser ablation of the seizure focus can be effective options for some with drug-resistant MTLE, resulting in seizure freedom in 50-75% of cases. However, these surgeries are tissue-destructive, can cause serious adverse effects, including increased risk of verbal memory impairment in the dominant hemisphere, and cannot be performed on both temporal lobes for those with bilateral MTLE. Thus, the development of non-destructive therapeutic strategies that target regions of the brain where seizures begin, spare surrounding tissue, and avoid the toxicities associated with ASDs, could provide a safer and more effective option. [0196] Inhibitory cell therapy represents a strategy that could locally restore normal GABAergic tone to seizure-onset foci and thereby repair underlying pathophysiology. Pallial (commonly referred to as “cortical”) GABAergic local circuit interneurons are the primary source of inhibition in the neocortex and hippocampus. Pallial interneurons are born in subcortical germinal zones and migrate tangentially to the cortex and hippocampus, where they disperse to their final positions and gradually acquire mature neurochemical and physiological characteristics. Different types of pallial interneurons are generated by distinct germinal domains in the developing subpallium: the MGE and the nearby preoptic area (POA) generate somatostatin (SST)- and parvalbumin (PV)-expressing pallial interneuron classes, while the caudal ganglionic eminence (CGE) generates serotonin receptor 3A (HTR3A)-expressing interneuron classes. A loss of MGE-derived interneurons, including SST, neuropeptide Y (NPY), and PV-expressing subtypes, has been observed in hippocampal tissue resected from MTLE patients or post-autopsy. Furthermore, mutations in genes required for interneuron generation and function have been identified in various developmental epileptic disorders. Consistent with these findings, SST and PV interneuron subtypes are lost or dysfunctional in animal models of epilepsy. Additionally, seizures can be induced by selective MGE-type pallial interneuron ablation and reduced by selective MGE- type interneuron activation. [0197] Proof-of-concept efficacy of inhibitory interneuron cell therapy has been demonstrated after transplantation of primary embryonic rodent MGE cells into experimental models of epilepsy. The transplanted primary MGE cells locally dispersed, stably persisted, matured into pallial interneuron subtypes, and suppressed seizures. A renewable cell source of human MGE-type interneurons would encourage widespread clinical use. [0198] Human pluripotent stem cells (hPSCs) represent an expandable cell source from which inhibitory interneurons can be derived. Multiple derivation methods for generating human GABAergic neurons from MGE-like progenitors have been published using either embryonic or induced pluripotent stem cells. Subsequent transplantation studies of hPSC-derived GABAergic neurons into experimental epilepsy models reported promising results, including seizure reduction. However, despite the widespread use of the term “cortical interneurons”, these cell preparations were not specifically enriched for cortical or pallial-type MGE-derived interneurons. Rather, each consisted of a mixture of different GABAergic populations, including CGE-derived interneurons and likely non-migratory GABAergic projection neurons, as evidenced by marker expression and graft phenotypes in the above reports. This distinction is important because MGE progenitors produce several cell lineages in addition to pallial GABAergic interneurons, including GABAergic and cholinergic striatal interneurons, GABAergic and cholinergic subpallial projection neurons, oligodendrocytes, and astrocytes. Thus, while pallial MGE interneurons are specifically implicated in the pathophysiology of MTLE and represent the most anatomically and physiologically relevant population for cell replacement therapy, a clinically appropriate source of these cells has not been described previously in the literature, and the potential of human pallial interneuron cell therapy to suppress seizures has remained unexplored. [0199] A novel pallial MGE-type GABAergic interneuron cell therapy derived from a clinical-grade human embryonic stem cell (hESC) line was developed, as shown in Examples 2-9. Significant suppression of mesiotemporal seizures and histopathology improvement following cell transplantation into a preclinical MTLE model was demonstrated. The human pallial MGE-type interneurons were harvested and cryopreserved at a committed post-mitotic, migratory stage of development to ensure dispersion and integration within local circuits, mitigating the risks of proliferation and differentiation into undesired cell fates. Extensive molecular and functional characterization of the cell therapy candidate was made, including single-cell RNA sequencing (scRNA-seq), in vitro migration, and GABA secretion analyses. Following intrahippocampal transplantation into a chronic mouse model of MTLE, hESC-derived pallial MGE-type interneurons were analyzed for cellular migration and persistence, graft composition, synaptic connectivity, and dose- dependent reduction of seizure activity. [0200] In some embodiments, human pallial MGE-type GABAergic interneuron cell therapy can provide treatment of drug-resistant focal epilepsies. Example 2 [0201] This non-limiting example provides materials and methods used in Examples 3-10. A. In vitro hESC line and banks [0202] The pallial MGE-type GABAergic interneurons described in this study were differentiated from research-grade working cell banks derived from a human embryonic stem cell (hESC) line. The cell line is listed in the NIH hESC Registry as an “Approved Line” (eligible for use in NIH-supported research). Donor consent was obtained for use of the cells in research, clinical and commercial development. Donor screening was performed using FDA’s Donor Eligibility Guidelines for HCT/Ps. The cell line was derived, expanded, and banked under cGMP conditions using qualified raw materials to generate a GMP seed cell bank (SCB), and research-grade master cell banks (rMCB) and working cell banks (rWCB). Karyotypic analysis and pluripotency marker expression were assessed across all hESC cell banks, demonstrating genomic stability and high purity. The pluripotent stem cell banks were tested for sterility and found negative for relevant viruses, mycoplasma, and adventitious agents. Pluripotency of the undifferentiated cells was demonstrated by expression of markers such as TRA-1-60, OCT-4, and NANOG; the in vitro differentiation of the cells to endoderm, ectoderm, and mesoderm lineage; and the demonstration of teratoma formation when engrafted in vivo. hESC stability [0203] The hESC working cell banks (WCB) were tested for genetic stability per ICH Q5D (ICH_Q5D 1998) by evaluating the cell substrate for consistent production of the intended cell fate. MGE-type patterning and differentiation to pallial interneurons using the manufacturing process was initiated from rWCB ESCs after up to five additional passages of ESC expansion to reflect the intended limit of cultivation, and genetic stability was characterized using the complementary orthogonal methods of karyotype analysis by G- banding and single nucleotide polymorphism (SNP) arrays. Since the product being manufactured is post-mitotic and karyotype analysis by G-banding requires mitotic cells, karyotype analysis was performed during the ESC expansion and genome-wide genomic copy number variants (CNVs) and regions of homozygosity analysis (ROH) were assessed during both ESC expansion and end-of-process (EOP) interneuron differentiation using SNP arrays. [0204] In addition, exon capture, next generation sequencing and variant analysis of the TP53 gene was performed using gDNA isolated from ESCs and EOP interneurons, with at least 100X on target coverage. Libraries were prepared using CleanPlex® TP53 Panel (Paragon Genomics) and sequenced on the Illumina platform and analyzed by ACGT Inc for TP53 mutations recurrently acquired in human pluripotent stem cells during in vitro culture (Merkle et al, 2017). The characterizations demonstrated: [0205] a. no genetic abnormality occurs during ESC expansion or following the interneuron production process from ESCs at the maximum limit of in vitro cultivation; and [0206] b. consistent production of the intended pallial interneuron cell product at the maximum limit of in vitro cultivation. hESC expansion [0207] A cGMP grade hESC line was adapted to a feeder-free, xeno-free culture system using human recombinant vitronectin (A27940, Life Technologies) coated dishes, Essential 8 medium kit (A2656101, Life Technologies) and dissociation reagent ReLeSR (100-0484, STEMCELL Technologies). Media was changed daily, and cells were passaged every 5 days, for a total of 5 passages, before being cryopreserved to sequentially generate a GMP SCB, and research-grade rMCBs and rWCBs. MGE pallial-type interneuron differentiation [0208] For each differentiation experiment, one vial of rWCB was thawed. The thawed hESCs were seeded into adherent culture and expanded for 5 days post-thaw using conditions described above. To initiate differentiation, the expanded hESCs were dissociated into a single cell suspension using StemPro Accutase (A1110501, Life Technologies) and resuspended in differentiation media consisting of Neurobasal-A (50%; 10888, Life Technologies) and DMEM/F12 (50%; 21331, Life Technologies), supplemented with GlutaMAX (1X; 35050-061, Life Technologies), B-27 without Vitamin A (1X; 12587-010 Life Technologies), N2 supplement-B (1X; 07156, Stem Cell Technologies), Penicillin- Streptomycin (1X; 15140-122, Life Technologies), L-Ascorbic Acid (200μM; A5960, Sigma), β-Mercaptoethanol (55M; 21985-023 Life Technologies), and MEM non-essential amino acids (1/2X; 11140-050, Life Technologies). The resuspended hESCs were exposed to patterning and differentiation cues from day 0, adjusting small molecule combinations over time and changing media every 2 to 3 days, using only chemically-defined reagents and small molecules, in the absence of knockout serum replacement (KSR). [0209] During the three main protocol phases (Fig 10A), small molecules modulating the listed cell signaling pathways were introduced to promote robust MGE patterning and differentiation into pallial-type GABAergic interneurons. During the neuroectoderm specification and MGE patterning phase, ROCK inhibitor (Y27623 10μM; 1254 Tocris) with TGFβ and BMP pathway inhibition induced neuroectoderm (SB431542 10μM; 1614 Tocris / LDN193189250nM; 6053 Tocris). WNT pathway inhibition conferred forebrain identity (XAV939 10μM; 3748 Tocris) and SHH pathway activation induced ventral forebrain MGE-like progenitors (SAG 100nM; 4366 Tocris). During the second MGE progenitor expansion and pallial interneuron commitment phase, a MEK pathway inhibitor was applied to further improve the efficiency, kinetics, and specificity of pallial-type GABAergic interneuron lineage (PD0325901 2μM; 4192 Tocris). Finally, during the third phase, inhibitors of the MEK (PD0325901 2μM; 4192 Tocris), CDK (PD0332991 2μM; S1116 Selleck Chemicals) and NOTCH (DAPT 10μM; 2634 Tocris) pathways were added to induce cell cycle exit and differentiation into post-mitotic MGE pallial-type GABAergic interneurons. Cell batch processing and cryopreservation [0210] At the end of the differentiation process, cells were harvested and dissociated to single cells using TrypLE™ Select Enzyme and Benzonase (1/10000; Sigma Aldrich). A portion of the harvested cell suspension was subsequently processed using magnetic-activated cell sorting (MACS) for ERBB4. Single cells were incubated with a biotinylated primary antibody against human ERBB4 (BAF1131 R&D Systems), followed by incubation with Anti-Biotin MicroBeads (130-105- 637, Miltenyi Biotec), and magnetic sorting was performed on the CliniMACS according to manufacturer instructions (Miltenyi Biotec). Unsorted (pre-sort) and sorted (post-positive selection) cell populations were cryopreserved using the CryoMed controlled-rate freezer (Fisher Scientific), before further storage in vapor-phase liquid nitrogen. Immunocytochemistry [0211] Thawed cells were counted using the NC-200 cell counter (Chemometec) and seeded into 384-well plates coated with Poly-L-Ornithine/Fibronectin/Laminin (PO/Fib/Lam) at ~4.0E5-4.3E5 cells/cm2. Cells were fixed with 4% Paraformaldehyde (PFA) for 10 minutes 3-16 hours after plating and processed for staining within two weeks. Briefly, cells were incubated with a blocking buffer (10% Goat Serum, 0.1% Triton X-100 in DPBS (Dulbecco’s phosphate-buffered saline)) for 30 minutes at ambient temperature. Primary and secondary antibody dilutions were prepared in blocking buffer and kept on ice. Primary antibody incubation was done at 4°C overnight, followed by two 30-minute washes with PBS-T (DPBS, 0.1% Triton X-100). Secondary antibodies (Alexa Fluor conjugated, Life Technologies) incubation was done at ambient temperature in the dark for 2 hours, followed by two 30-minute washes with PBS-T. The second wash was replaced with DPBS for imaging and storage. Aspiration and washes in 384-well plates were automated using the plate washer ELX406 (Biotek). [0212] Images were acquired using the Leica Dmi8 microscope with a 20X objective. A minimum of three-five fields of view were captured (typically 250-350 cells per field) for each sample and antibody combination. Analysis was performed manually using ImageJ software. [0213] For higher throughput sample images acquisition, analysis and quantification, the high content screening imaging system CX5 (Life Technologies) was used. Independent combinations of antibodies (up to 4 independent channels for the detection of Hoechst, Alexa Fluor AF 488, AF547 and AF650) were acquired independently with specific exposure times. Adjusting background correction and segmentation parameters, using “spot detector” bio application, nuclei were identified as primary objects to define regions of interest on subsequent channels, and determine percent of positive cells expressing a given marker, based on morphological and intensity thresholding. Assessment of residual pluripotent cells by flow cytometry [0214] Cells were stained on day 28 and at the end of process (post-thaw) with PE/Cy7 anti-human-TRA-1-60 (Biolegend) for surface TRA-1-60, Fixable Far Red dye (ThermoFisher Scientific) for viability and AF488 anti-human-OCT4 (BD Bioscience) for intracellular OCT4. The cells were analyzed using an Attune-NxT Acoustic Focusing Flow Cytometer and data were analyzed using FlowJo (BD Biosciences) software. To assess the presence of residual pluripotency markers in the final cryopreserved product, an extensive qualification was performed to determine the assay repeatability, accuracy, linearity and limits of detection (LOD) per ICH Q2 guidelines. Samples were stained in triplicate (1E7 cells per sample) for better population statistics. From this study the method was determined to be accurate in detecting pluripotent cells at a LOD of 0.002%. When the method was employed to analyze samples at the end of the process, the percentage of pluripotent cells detected was always below the LOD. Primeflow [0215] Cells were thawed, counted using the NC-200 cell counter, stained using Fixable Aqua Dead Cell Stain Kit (Life Technologies, cat# L34957), and processed for RNA Primeflow assay (Thermo Fisher, cat# 88-18005-210) according to the manufacturer’s instructions. Reactions were run in triplicate. Data were acquired using the Attune NXT Flow Cytometer (Life Technologies). All events in the sample were recorded (in the range of 6E4-3E5). Results were analyzed using the FlowJo software. Fixable Aqua and FSC were used to gate live cells. Single cells were then gated on forward scatter area and height (FSC- A versus FSC-H) and side scatter area and height (SSC-A versus SSC-H). Using dapB as the negative control, gates were set in histogram plots for AF488 and AF647 probes. The same gates were then applied to all the test samples accordingly to determine the percentage of expression in cell lots. Quantitative results were reported as the average ± standard deviation of 3 technical replicates. GABA release [0216] To perform the GABA release assay, cryopreserved cells were thawed, and the viability and cell concentration were determined using the NC-250 cell counter (Chemotec). Cells were seeded onto a polyornithine/fibronectin/laminin coated 96-well plate at a density of 0.65E6 cells/cm2 in culture media. Each cell lot was seeded in six wells, and cells were cultured at 37°C, 5% CO2 for 8 days, with media changes every 2-3 days. On day 8, spent medium was replaced with fresh pre-warmed medium either alone or supplemented with 90 mM potassium chloride (in triplicate wells per condition). After a 30-minute incubation at 37°C, 5% CO2, cell-free supernatants were collected and stored at -80°C. The samples were submitted for liquid chromatography and mass spectrometry (LC/MS-MS) analysis of GABA and Acetylcholine (Ach) neurotransmitter content (Charles Rivers Laboratories). [0217] To confirm functional specificity, the GABA release assay was performed using hESCs and spinal motor neurons (SMNs, BrainXcell), neither of which normally secrete GABA. hESCs were seeded at a density of 25E3 cells/cm2 in E8 media containing ROCK inhibitor seventy-two hours prior to sample collection. One day post-seeding, the media was changed to the same neuronal culture media as hESC-derived interneurons, and the cells were fed daily until sample collection. SMNs were thawed and seeded into a polyornithine/fibronectin/laminin coated 96-well plate at a density of 0.65E6 cells/cm2 and cultured for 8 days as described by the manufacturer. The sample collection was performed the same way for ESCs and SMNs as for the hESC-derived interneurons on day 8. In vitro cell migration [0218] To assess the migration potential of hESC-derived pallial MGE-type interneurons compared to human fetal MGE-derived interneurons and other in vitro-derived GABAergic cell preparations, a migration assay was developed, in which cells were aggregated and embedded into a MatrigelTM (CB-40230, Fisher Scientific) drop covered with culture medium, and then incubated for three days to allow for the visualization and quantification of cells migrating away from the main cell aggregate. Primary human MGE was dissected from mid-gestational age tissue (GW18-20) followed by dissociation and sorting for ERBB4. All hPSC-derived interneurons were thawed prior to aggregation. The commercial sources of hPSC-derived GABAergic cells were from Cellular Dynamics International (vendor “X”: iCell GABA Neurons, cat #C1008) and BrainXell (vendor “Y”: GABAergic Neurons, cat #BX-0400). Cells from different sources were prepared by one operator, assigned a random ID and handed to a different operator de-identified for assays and data analyses. [0219] To perform the assay, 5E3 cells in 100 μl of culture medium were spun down in 96-well V bottom plates (S-bio, MS-9096VZ) and allowed to aggregate at 37°C, 5% CO2 over a period of three days. The aggregates were then embedded into a MatrigelTM drop in the center of a 96-well flat bottom assay plate with the aid of a dissecting microscope inside the biosafety cabinet (BSC) (one aggregate per well, twelve aggregates per sample). After a 15-minute incubation at ambient temperature, 200 μl of culture medium was added to the wells, followed by incubation at 37°C, 5% CO2 for three days. [0220] On day 3 of migration, samples were fixed for 30 minutes with a 2% PFA and 1X Hoechst solution at ambient temperature, protected from light. The fixation solution was washed away three times using DBPS. Migration images were acquired using the CX5 instrument with a 4X objective, projecting the maximum intensity across 375 µm (15 z-plans, 25 µm steps). The number of Hoechst positive cells that migrated away from the aggregate was quantified automatically using “spot detector” bio application. Percentage of migrating cells was determined based on the number of Hoechst positive spots detected divided by 5E3 (input cells that were aggregated). Single cell RNA sequencing [0221] To objectively assess cell composition, scRNA-seq analysis was performed using the 10X Genomics platform on the hESCs prior to the start of differentiation, hESC-derived MGE-type VZ-like progenitors on day 14 of differentiation, and six pairs of unsorted/sorted cell lots at the end of the differentiation process. All samples were thawed the day of capture and transported on ice to SeqMatic (Fremont, CA) for downstream processing and data generation. [0222] Individual cells were captured and barcoded using the chromium controller, cDNA libraries were prepared using next GEM 3’ V3.1 kits (10x Genomics), cDNA libraries were quantified using the Agilent Tapestation 4200 and pooled for sequencing. Pooled libraries were quantified using Lightcycler 96 qPCR and sequenced by the Illumina NovaSeq 6000. Typically, ~8E3-12E3 cells were captured per sample. About 200 million reads were obtained for each sample, with an average read depth of ~20,000 reads per cell. [0223] Cell Ranger v3.1.0 (10x Genomics) was used to demultiplex FASTQ files for each sample, align reads to the human GRCh38 genome downloaded from 10x Genomics, and quantify the expression levels for each gene in each cell from each sample. R version 4.0.3 and Seurat v3.2.2 were used to quality control, normalize, cluster, and visualize the cells from all samples. Cells were filtered for quality by having at least 1000 expressed genes, at least 1000 unique reads, no more than 20% reads of mitochondrial genes and no more than 40% reads of ribosomal genes. Cells were normalized by the ‘LogNormalize’ method. The top 3000 genes were identified by ‘FindVariableFeatures’ with ‘vst’ selection method for downstream integration analysis. Seurat CCA (Canonical Correlation Analysis) integration workflow was applied to remove the batch effects between different cell lots. hESCs and Day 14 progenitors were merged with the integrated differentiated lots for clustering. PCA (Principal component analysis) was applied, 30 PCs (principal components) were selected, and cells were clustered with Seurat standard workflow. Using a dimension reduction technique called UMAP (Uniform Manifold Approximation and Projection), cells are visualized in a 2-dimensional space and colored by groups, where each dot represents one cell, and groups of cells with similar gene expression form into clusters. Top markers for each cluster were identified by using the Seurat ‘FindAllMarkers’ function with ROC method and the cell type of each cluster were determined by the expression of typical cell markers of each type. Gene expression was visualized with violin-plot, dot-plot and feature-plot built in Seurat package. [0224] The sequencing data discussed herein have been deposited in NCBI’s Gene Expression Omnibus and are accessible through GEO Series accession number GSE208672. [0225] To compare and classify in vitro hESC-derived interneurons with published data, human developing GE snRNAseq data were downloaded from GEO dbs (Shi et al., 2021), and processed to identify MGE, CGE, LGE and other clusters as described in the original report. PCA and UMAP models of cell types were computed and the human developing GE reference was constructed by following the Seurat reference mapping procedure. The cell type classification of hESC-derived interneurons was assigned based on prediction scores using the human GE cells as a reference. Each in vitro cell was assigned a score between 0 and 1 for each cell type based on the transcriptomic similarity between the query and the reference (human developing GE cells). The prediction scores of each cell for each cell type category were projected onto UMAP clusters and the predicted-cell-type compositions (percentage) for each cluster were visualized with the heatmap. B. In vivo Animals [0226] Up to 85 NOG (NOD.Cg-PrkdcscidIl2rgtm1Sug/JicTac) male mice per study were obtained from Taconic in the range of approximately 5-6 weeks of age for comparisons of different cell lots or doses and vehicle groups. Male mice were chosen because they display more consistent seizures in this model. Mice were assigned a unique identifier number on arrival, which was marked on the mouse by ear-notches and tail tattoos. Animals were maintained in an animal facility under standard temperature and humidity on a 12:12 light/dark cycle. Bottled water and standard chow were provided ad libitum. Single-use cages were used with irradiated Alpha-Dri bedding. Prior to induction, animals were co-housed when possible. Colony health was monitored through monthly diagnostic sample submission for microbiology. All described surgical procedures were accompanied by s.c. meloxicam (Metacam® 10 mg/kg in 2ml/kg i.p.) as a non-steroidal anti-inflammatory drug, antibiotic enrofloxacin (Baytril® 10 mg/kg in 4.4 ml/kg s.c.), and local anesthesia on the scalp with bupivacaine (2.5 mg/kg in 5 ml/kg s.c.). After every surgery, animals received 1 ml warmed Ringer’s solution s.c. to rehydrate, and their cages were placed on a heating pad until full recovery from anesthesia. Epilepsy induction [0227] After acclimation of 2 weeks, animals received 0.21 µg kainic acid (KA; Tocris) dissolved in 50 nL NaCl into the right dorsal hippocampus to induce epilepsy (coordinates in relation to Bregma: AP -2.0; ML +1.6; DV -1.65), using a pulled glass needle with 70-90 µm diameter at the tip and a connected microinjection system (Narishige). At this first surgery, the body weight of the animals was 23-24 g on average. After injection of KA, mice were kept under isoflurane anesthesia for a total of 1 hour to avoid the more severe seizures associated with recovery from inhaled anesthesia. After recovery from anesthesia, animals were closely monitored for occurrence of generalized seizures. All mice began seizing within 90 min post-anesthesia and were then returned to the animal housing room in single-housed cages. Status epilepticus (SE) was not interrupted in this model. Mice were injected with 1 mL lactated Ringer’s solution to ensure rehydration during/after SE. Additionally, food pellets and water as a gel were provided at the bottom of the cage. If necessary, mice were placed on heating pads and manually provided with Ensure® liquid diet supplement on the day after SE. If failure to thrive was observed, the mouse was euthanized. Mortality during and within the first days after SE was <10%. Cell transplantation for focal KA model [0228] Transplantation of hESC-derived MGE-type pallial interneurons or vehicle (serum-free base medium) was performed four to five weeks after SE induction to ensure that the mice displayed spontaneous seizures and were chronically epileptic prior to treatment. Cells were transplanted using the same system as for the KA injections, a pulled glass needle with 70-90 um diameter at the tip and a connected microinjection system (Narishige). Cells were injected in 4-6 different deposits per brain hemisphere in a dose of 5E3 (5K) – 6E5 (600K) cells per deposit depending on the target dose from 2.5E4 (25K) to 1.5E6 (1.5M) per hemisphere. After delivery of the hESC-derived interneurons, the needle remained in the tissue for another 30 seconds to prevent backflow of cell suspension along the needle tract. Control mice received similar amounts of vehicle solution into the same deposit coordinates. Electrode implantation and EEG recording [0229] For recording an electroencephalogram (EEG), transmitters from Data Science International (DSI) were implanted and connected in-house to a custom-made bipolar electrode (PlasticsOne). The DSI transmitter was implanted subcutaneously over the left flank of the mouse and the electrode was lowered into the right dorsal CA1 of the hippocampus into the same site as the previous KA injection (coordinates in relation to Bregma: AP -2.0; ML +1.6; DV -1.65). The electrode was secured in the skull by implanting three holding screws (2 rostral, 1 caudal) and Loctite glue. Implantation happened in the same surgery as cell/vehicle transplantation or within a few weeks of transplantation surgery. After DSI transmitter implantation, EEG and video recordings (Ponemah; DSI) were acquired in multi-day 24-hour sessions for each animal enrolled in the study; the data were saved to a server approximately daily and archived at least monthly on backup storage hard drives. EEG was recorded 24/7 for 1-3 weeks at various time points post-SE (Fig. 4A) using Ponemah software. Recording time points for most studies were between 1-2 MPT, 5, and 7 MPT. Some studies (lot 3S & 4S) were recorded also at earlier and later time points (Figs. 14D, 14E). Brain slice electrophysiology [0230] For electrophysiology studies, cells were seeded onto PO/Fib/Lam coated multiwell plates in culture media. Following overnight incubation at 37°C, 5% CO2, culture medium was replaced with fresh medium containing lentivirus supernatants (Lenti-UbC-GFP or Lenti-Syn-ChR2-YFP) based on the optimal titration that was determined empirically in a separate experiment to achieve 95% GFP+ or YFP+ expression. After a three-day incubation, culture medium was removed followed by three washes with PBS to remove any residual viral particles. Cells were harvested using 0.25% trypsin solution, quenched with FBS (20% final). [0231] Upon harvesting, cells were concentrated by centrifugation (150g, 4 minutes at room temperature). Concentrated cell suspension was loaded into beveled glass micropipettes (internal diameter ≈80-90 μm, Wiretrol 5 μl, Drummond Scientific Company) prefilled with mineral oil and mounted on a microinjector. Concentration of the cell suspension within the needle was determined using a hemocytometer just prior to the injection. Postnatal day (P)0-2 Scid-beige (CRL) mice were anesthetized by hypothermia for 1-2 minutes and subsequently positioned in a clay mold to stabilize the head. Recipient mice were injected 3 times bilaterally with 50E3 cells/injection site (total = 300E3 cells per pup). Injections were performed 0.75, 1.25, 2.5 mm anterior from Lambda, 0.75, 1.0, 1.0 mm away from the midline (respectively) and at a depth of 0.35 mm from the surface of the skin. After the injections were completed, the needle was slowly removed and transplant recipients were placed on a warm surface to recover from hypothermia. The mice were then returned to their mothers until they were weaned (P21). [0232] Adult (6-8 weeks old) NOG male mice were transplanted as described above. A total dose of 200E3 cells/hippocampus was delivered into the mouse hippocampus at 4 different sites (50E3 cells/injection) with respect to bregma (AP: -1.85; ML: +1.8; DV: - 1.7 mm; AP: -2.5; ML: +2.65; DV: -1.9 mm; AP: -3.15; ML: +2.8; DV: -2.4 mm and AP: - 3.15; ML: +3.25; DV: -3.45 mm). Mice up to one year of age were deeply anesthetized with intraperitoneal injection of freshly prepared Avertin (250 mg/Kg) and perfused with ice-cold sucrose-based solution (210 mM Sucrose, 2.5 mM KCl, 10 mM MgSO4, 2 mM CaCl2, 1.25 mM NaH2PO4, 24 mM NaHCO3, 11 mM glucose). The brain was removed and sectioned into 300 μm thick slices, which were transferred to 34℃ ACSF (126 mM NaCl, 3 mM KCl, 2 mM MgCl2, 2 mM CaCl2, 1.2 mM NaH2PO4, 26 mM NaHCO3, 10 mM glucose) for 30 minutes at room temperature for no more than 6 hours for later use. [0233] For older animals, a previously published “protective recovery method” was adapted. Mice were deeply anesthetized and transcardially perfused with ice-cold “NMDG-HEPES aCSF” (92 mM NMDG, 92 mM HCl, 2.5 mM KCl, 1.2 mM NaH2PO4, 30 mM NaHCO3, 20 mM HEPES, 25 mM glucose, 5 mM sodium ascorbate, 2 mM thiourea, 3 mM sodium pyruvate, 10 mM MgSO4, 0.5 mM CaCl2). The brain was dissected and sectioned into 300 μm coronal slices. Slices were transferred to 34℃ “NMDG-HEPES aCSF” for 40 minutes to recover. During the recovery phase, Na+ spike-in solution (2 M NaCl in NMDG-HEPES aCSF) was added at the following time points: 15 min: 0.25 mL; 20 min: 0.25 mL; 25 min: 0.5 mL; 30 min: 1 mL; 35 min: 2 mL. Slices were then stored in “HEPES holding aCSF” (92 mM NaCl, 2.5 mM KCl, 1.2 mM NaH2PO4, 30 mM NaHCO3, 20 mM HEPES, 25 mM glucose, 5 mM sodium ascorbate, 2 mM thiourea, 3 mM sodium pyruvate, 2 mM MgSO4, 2 mM CaCl2) at room temperature for no more than 6 hours for later measurements in “recording aCSF” (124 mM NaCl, 2.5 mM KCl, 1.2 mM NaH2PO4, 24 mM NaHCO3, 5 mM HEPES, 12.5 mM glucose, 2 mM MgSO4, 2 mM CaCl2). All solutions were balanced for 30 minutes with carbogen (95% O2, 5% CO2) before use. [0234] Borosilicate glass pipettes (4-8 Mohm) were backfilled with a solution containing: 140 mM K-gluconate, 2 mM MgCl2, 10 mM HEPES, 0.2 mM EGTA, 4 mM MgATP, 0.3 mM NaGTP, 10 mM Phosphocreatine d-tris, and 0.25% (g/100mL) biocytin. Signals were collected at room temperature at a sampling rate of 50K, filtered using a 10K bessel filter (MultiClamp 700B, Axon Instruments, Molecular Devices) and digitized (Digidata 1320A, Axon Instruments, Molecular Devices). Recording data were further filtered using Clampfit (v10.7), “Lowpass” function with Gaussian type and 2000 Hz -3 dB cutoff. Stimfit (0.15.8, github(dot)com/neurodroid/stimfit) and python were used to calculate and plot the parameters. Behavior [0235] For all assays, experimenters were masked to animal treatment group, and test order was based on the experimenter randomly selecting a cage. [0236] Modified Irwin’s Test: General health and wellness of the animals was also assessed using a modified Irwin screen adapted from a protocol used to test safety and tolerability of anti-seizure drugs in naive and epileptic mice. An animal’s sensitivity to touch, noise, tail elevation, and spatial locomotion (mobility) were evaluated, as well as their body position and fur condition. A value of 2 was set as the usual expected reaction for a healthy mouse in the test. Animals were tested in an empty mouse cage in their housing room. One experimenter administered the test while two other experimenters scored the animal or its reaction. Animals were assessed at least twice during the study. If an animal had a generalized seizure during the test, it was excluded. The two evaluators’ scores were averaged for each condition. Depending on the number of groups, a one-way ANOVA or t- test was run. If the data were nonparametric, Kruskal-Wallis or Mann-Whitney was run. [0237] Open Field Test: The Open Field test was used to determine exploration, general locomotor activity and anxiety, and animals were tested at approximately 6 MPT. A four-arena maze (each 40cm x 40cm) was used to analyze multiple animals at once. Animals were acclimated to the test room for at least one hour prior to the test. An animal was placed in the center of the open field and allowed to explore for five minutes and then returned to its home cage. Animals that experienced a generalized seizure during the test were returned to home cage and re-tested after 30 minutes if possible. Video was recorded using Media Recorder (Noldus) and analyzed using Ethovision XT (Noldus) software. The apparatus was cleaned between each animal using Nolvasan® solution to minimize odor cues. Animals were excluded from analysis if they rotated in one direction more than 10x compared to the other direction. Evaluations included the total distance traveled, total amount of time spent in the center of the maze, and frequency of rearing behavior. Depending on the number of groups, a one-way ANOVA or t-test was run. If the data were nonparametric, Kruskal-Wallis or Mann- Whitney was run. [0238] Barnes Maze Test: The Barnes Maze is a dry-land maze used to assess visual-spatial learning and memory in rats and mice, which is partially impaired in the focal kainate mouse model. The maze is an elevated circular platform with a diameter of 92 cm. Twenty 5 cm holes line the edge of the maze and a hidden chamber is placed underneath one hole. Visual clues were placed around the room and lights acted as a mildly aversive stimulus. Acquisition and probe trials were video recorded using Media Recorder and analyzed using Ethovision XT software. On the first day of testing, animals were familiarized with the maze and hidden chamber. The animal was first placed in a red plastic, open-ended cylinder in the center of the maze and after 10 seconds the cylinder was removed. The animal could explore the maze for 2 minutes and after this time the animal was gently guided to the hidden chamber. Once in the chamber, the animal remained there for 1 minute before being returned to the home cage. This step was repeated one more time if animals were resistant to entering the hole. Acquisition trials were run on Days 1-3, and up to three trials were conducted each day. Animals were placed in the room 1 hour before the first trial for acclimation. Each animal had up to 3 minutes to find the hidden chamber and if it did not, the animal was gently guided to the hidden chamber after the time elapsed. The location of the hidden chamber remained the same for all animals during the acquisition trials. The maze and hidden chamber were cleaned between each animal using Nolvasan® solution to avoid odor cues. Animal order was randomized using Random.org. Experimenters were masked to the animal’s treatment. Animals that experienced a generalized seizure during a trial were returned to home cage and retested after 30 minutes if possible. On Day 5 a probe trial was run. During this trial, the escape chamber was removed and each animal had up to 3 minutes to explore the maze. After 3 minutes, the animal was returned to its home cage. To assess long-term retention, an identical second probe trial was run approximately 10 days after the first probe trial. An animal’s trial was excluded from analysis if the animal had a seizure during the trial, the animal was continuously circling, or if the animal fell off the maze more than twice during the trial. Animals were also excluded during probe trials if they didn’t move more than 70 cm. The number of errors and escape latency to the hidden goal box was evalutated. A 2-way ANOVA was used for statistical analysis. If the data were nonparametric, Kruskal-Wallis or Mann-Whitney tests were used for statistical analysis. [0239] Y-Maze: The Y-Maze alternation test is used to determine exploration and spatial memory and has been used in the literature for assessing effects of GABAergic transplants in epileptic mice. The Y-Maze is a three-arm maze and each arm contains a visual cue. Animals were placed in the room one hour before the start of the test for acclimation. To begin the test, the animal is placed in the previously chosen “start” arm facing the center of the maze. The animal can explore for five minutes and then it is returned to its home cage. Animals that experienced a generalized seizure during the test were returned to home cage and re-tested after 30 minutes. Video was recorded using Media Recorder and analyzed using Ethovision XT software. The maze was cleaned between each animal using Nolvasan® solution to avoid odor cues. Animals were tested once, usually at the end of the study. Animals would be excluded from analysis if they didn’t enter each arm at least twice. Outcomes that were evaluated included the number of arms entered, percent alteration, and direction of alteration. Depending on the outcome evaluated, a one-way ANOVA or t-test was run. If the data were nonparametric, Kruskal-Wallis or Mann-Whitney was run. Perfusion [0240] At the scheduled termination time point, animals were transcardially perfused with cold saline followed by 4% paraformaldehyde. Brain tissue was collected and immersion fixed overnight in 4% paraformaldehyde, followed by cryoprotection with 30% sucrose in phosphate buffered saline. For animals found dead, brain tissue was collected when possible. EEG analysis [0241] EEG was analyzed by researchers masked to treatment and group allocation either in-house or by the CRO SynapCell (St. Ismier, France). EEG that was not readable due to bad quality of the recording was not sent out for analysis and the animal was excluded from the EEG results. In-house EEG was analyzed using Neuroscore (DSI). The read-out for this model was focal electrographic seizures. These ictal events were not present in sham-treated animals that did not receive an intrahippocampal kainate injection. Electrographic seizures are defined as synchronous activity with changes in spike frequency with a duration of at least 5 seconds at double the amplitude as baseline EEG. The inter-event interval was set at 1 second. Epileptic mice displayed around 11-15 electrographic seizures/30min early after SE in the MTLE model (Fig. 5F). [0242] The same experimenter read the EEG of the same animals at different time points post-transplant to limit variation. A 30-min interval of EEG was analyzed for electrographic seizures each day for 7 consecutive days per time point. All EEGs were analyzed from the same time of day if possible (16:00). Since EEG traces can become increasingly hard to analyze with time after implantation of the electrodes, the following criteria were applied: (1) if no clean trace for a duration of 30 min was found, the next clean 30 min interval within the next 3 hours was used; (2) if no 30 min clean EEG stretch was found between 16:00-19:00, the EEG was read between 15:00-16:00; (3) if there was no clean EEG interval of 30 min, at least 10 min (continuous) as close to the original time point (16:00) was analyzed; (4) if an event crossed the predicted start/end of the 30-min reading interval, it would still be counted. Animals that did not show any seizure activity at baseline were excluded from the study. RNA FISH [0243] RNA fluorescence in situ hybridization (FISH) was performed on fixed, frozen mouse brain sections using RNAscope Multiplex Fluorescent Reagent Kit v2 Assay (Advanced Cell Diagnostics cat# 323100) according to the manufacturer’s instructions. Briefly, 40 μm sections were post-fixed with 4% PFA and dehydrated with 50%, 70% and 100% ethanol. Sections were pretreated with hydrogen peroxide and target retrieval was performed. Following a 30-minute protease treatment, they were hybridized to probes targeting human GAD1 (Advanced Cell Diagnostics cat# 404031-C3) and human GAPDH, cross-validated not to recognize the mouse GAPDH gene (Advanced Cell Diagnostics cat# 442201-C2). Further amplification was performed according to the assay kit protocol, and Opal 520 (Akoya Biosciences cat# NC1601877) and Opal 690 (Akoya Biosciences cat# NC1605064) dyes were used to fluorescently label the probes. Tile scan images were acquired using the Leica Dmi8 microscope. Analysis was performed manually using the Leica Application Suite X (LAS X) software and values represented are the percentage of human GAPDH-positive cells that express GAD1 in 2 sections for each of n=10 animals with Lot 1-U and n=8 animals with Lot 1-S. Histology [0244] Brain tissue through the hippocampus was sectioned at 40 µM on a slide microtome or cryostat in 12 series of sections and processed for immunohistochemistry and chromogenic tissue stains. All brain sections examined were assessed for the presence of ectopic tissue and development of micropathology. Analysis involved determining if the electrode and cell transplantations had been appropriately targeted within the hippocampus, and persistence, distribution and fate of transplanted human cells: One series of sections was stained with Nissl or H&E to assess hippocampal damage and to identify any potential ectopic tissue or teratomas. Other tissue series were used to label for human cells (human nuclear antigen (HNA)), and several desired on-target markers such as LHX6, SST, PV, as well as off-target or proliferation markers such as DCX, GFAP, OLIG2, and KI67. Measurement of GC dispersion width and area [0245] Granule cell dispersion has been quantified by measurements of the GC layer width and area at -1.8 mm from Bregma, which is close to the site of kainate injection. The average GC layer width (three places, illustrated by white lines in Fig. 8B), and GC layer area (illustrated by the white boundary in Fig. 8B) were quantified using Zen Blue. Criteria for exclusion [0246] Animals that did not display behavioral seizures (SE) within 2 hours after intrahippocampal kainate injection were removed from the study. Animals were also excluded if EEG quality was too poor to detect electrographic seizures or if animals did not display epileptiform activity at any recording time point post-transplant. If an animal’s EEG trace had heartbeat or EMG with no clear EEG (seizures/spikes deriving from brain activity), it was excluded from the study. If an animal’s EEG trace displayed continuous spiking (sign of generalized seizure activity), it was excluded on that day. If an EEG could not be analyzed for at least 4 days at one recording time point, the animal would be excluded from the respective time point. In the case of EEG traces that displayed increased interictal activity and/or generalized seizures and in which it was thus hard to identify electrographic seizures, the EEG was analyzed for generalized seizures, and in rare cases in which animals had a high generalized seizure frequency (>3 seizures/day), they were excluded from analysis of electrographic seizures. If an animal did not survive to the endpoint of the study, the EEG data were collected and analyzed up to the point of animal’s death and all data were maintained in the study files. Statistical analysis [0247] For sample size calculations G*Power was used after initial experiments. Analysis was performed using GraphPad Prism 9 (GraphPad). Data were first tested for normal distribution. Parametric data were tested by t-test when 2 groups were compared, and by ANOVA if 3 or more groups were compared. Non-parametric data were tested accordingly by Mann-Whitney test or Kruskal Wallis test. Post hoc tests were performed if analysis of variance revealed differences. The level of significance was set to p=0.05. Most data were plotted as mean ± SEM; behavior scores were plotted as median with interquartile range. EEG data were analyzed on a per animal basis and reported as the mean of electrographic seizures and seizures per recording period. To compare results across multiple studies, the mean seizure frequency of the vehicle group was normalized to zero at each respective time point, while the individual cell-transplanted and vehicle-injected animals were plotted as a percent difference in seizure frequency from the respective vehicle control group mean. Randomization and masking [0248] Experimenters were masked to the treatment for the entire duration of the study and subsequent data analysis. During SE induction surgeries, 2-3 mice from each group cage were chosen randomly to distribute animals across all cages for a surgical day. All mice received the same treatment and were assigned a unique identifier number after surgery. For transplantation surgeries, mice were randomly selected from the holding rack (8 single- housed cages per row, per transplantation day at least 2 cages per row were selected). Treatment group allocation was only noted on surgery sheets and on an electronic database. Access to physical sheets and the database was limited to one person not involved in the study until the study was fully completed and all data were analyzed. The EEG files did not reveal the animal number. EEG was read on a per-channel basis by researchers who were masked to the treatment and animal identifier. The code for channel/animal number was kept at separate sites from the site of experimentation. The experimenters also had no information on the scope of the study, the treatment specifics or time points that they were analyzing. In- house data review was also performed in a masked manner and traces did not contain information to allow identification of the animal number or treatment group. In behavioral studies, the experimenters remained masked to treatment groups throughout the study and the testing order was either random cage selection from the housing rack or assigned by using the website random.org. All histological processing was done in a masked fashion by assigning the animals a new, coded identification prior to perfusion by a person not involved in the study. With these levels of masking in place, it was not possible to correlate EEG data with the histological analysis before all analyses were completed. Example 3 [0249] This non-limiting example shows differentiation of hESCs into highly enriched pallial MGE-type GABAergic interneurons. [0250] During brain development, MGE precursors, defined by the expression of NKX2-1 within the SOX1+, FOXG1+, DLX1/2+ ventral telencephalon (Figs. 9A-9F), give rise to multiple neuronal classes. The LHX6 transcription factor is induced by NKX2-1 in all MGE-derived GABAergic telencephalic lineages (Fig. 2A). LHX6 expression is largely maintained into adulthood in GABAergic lineages, including nearly all SST- and PV- expressing interneurons within the adult cortex and hippocampus. Pallial interneurons express tyrosine kinase receptor ERBB4, which is required for tangential migration. In addition, pallial MGE-derived interneurons are distinguished from the other GABAergic lineages by expression of MAF and MAFB and downregulation of NKX2-1 and LHX8 (Fig. 2A). In contrast, subpallial MGE-derived GABAergic and cholinergic neurons maintain NKX2-1 and/or LHX8 expression. While several studies reported induction of NKX2-1 from hPSCs along with a GABAergic neuron phenotype, they did not demonstrate downregulation of NKX2-1 and LHX8, or co-expression of LHX6 with MAF, MAFB, and ERBB4, specific to the pallial MGE lineage. [0251] FIGs. 9A-9H: In vitro characterization of hESC-derived VZ-like MGE progenitors on Day 14. (FIGs. 9A-9F) Comparison of marker expression in hESC- derived MGE-like progenitors by immunocytochemistry (ICC) with in situ hybridization data from the Allen Developing Mouse Brain Atlas, E13.5 (2008). (FIGs. 9A-9C) Combination of FOXG1, NKX2-1 and OTX2 expression in the vast majority of hESC-derived progenitors is consistent with rostroventral MGE patterning corresponding to the ventricular zone (VZ)-like developmental stage. (FIG. 9D) LHX6 expression defines the MGE subventricular zone (SVZ) and mantle zone (MZ), and is not yet expressed at this stage of differentiation. (FIGs. 9E, 9F). Markers corresponding to off-target regions including dorsal telencephalon (PAX6) and hypothalamus (NKX2-2) are not expressed in the hESC-derived MGE-like progenitors. (FIGs. 9G, 9H) Marker quantification across repeat scale-up differentiation experiments (FIG. 9G, n=41) and specifically in lots 1 and 2 (FIG. 9H). [0252] FIGs. 2A-2G: Post thaw in vitro characterization of end-of-process cell lots. (FIG. 2A) Simplified schematic of neuronal subtypes derived from the MGE progenitor domain (FOXG1+ DLX1/2+ NKX2-1+), including pallial GABAergic interneurons (IN) that migrate to the cortex and hippocampus, as well as multiple lineages that remain in the subpallium. The latter consist of striatal GABAergic and cholinergic Ins, cholinergic projection neurons (PN), and GABAergic PNs of the globus pallidus. The listed genes play critical roles in the specification of the indicated neuronal lineages. (FIGs. 2B, 2C) Representative ICC images showing expression of the MGE marker LHX6 as well as pallial MGE markers MAFB, MAF and ERBB4 in the unsorted and sorted Lot 1. (FIG. 2D) Marker quantification for unsorted (gray bars) and sorted (white bars) cell lots after cryopreservation and thaw. Each dot is from an independently manufactured lot (n=10 to 18). Data are expressed as a mean ± SEM. (FIGs. 2E, 2F) Neurotransmitter release assay from hESC-derived MGE interneuron lots (unsorted and sorted lots are plotted together, as no significant differences were observed), undifferentiated hESCs and spinal motor neuron cultures. (FIG. 2G) Viability quantification from multiple unsorted/sorted cell lots after cryopreservation and thaw. [0253] A clinically-compatible manufacturing protocol using chemically defined reagents was developed to differentiate hESCs into MGE progenitors and subsequently into pallial-type GABAergic interneurons (Fig. 10A). After a two-week patterning phase, over 90% of the cells in culture co-expressed SOX1, FOXG1 and NKX2-1 proteins, and over 80% of cells additionally co-expressed OTX2, while fewer than 10% of the cells expressed LHX6 at this early stage (Figs. 10A-10G; N=41 independent differentiations). Since OTX2 is expressed in the MGE ventricular zone (VZ), and LHX6 begins to be expressed in the MGE subventricular zone (SVZ) (Figs. 9C, 9D), this combination of markers indicates that day 14 MGE-like progenitors correspond to a VZ-like stage. [0254] FIGs. 10A-10J: Efficient and reproducible hESC differentiation into MGE-type pallial interneurons. (FIG. 10A) Schematic of MGE pallial-type interneuron differentiation protocol and key markers used to characterize each stage. (FIGs. 10B-10G) Representative images (FIGs. 10B, 10D, 10F) and automated quantification (FIGs. 10C, 10E, 10G) of selected markers by ICC at weeks 2, 3, 4 and 6, as cells transition from MGE-type VZ-like neural progenitor cells (NPC) into early postmitotic pallial interneurons. Data are presented as mean ± SEM for the percent of positive cells (n=18 to 32, from 8 independent experiments, 5 operators); Not determined (ND). (FIGs. 10H-10J) Effect of a MEK pathway inhibitor during differentiation on subpallial marker LHX8 and pallial interneuron marker ERBB4. [0255] Upon further differentiation, the expression of markers that distinguish pallial and subpallial lineages was investigated in five independent cell banks (n=18-32 independent differentiation experiments; Figs. 10B-10G). These experiments demonstrated that the MGE progenitor markers NKX2-1 and OLIG2 increased over several weeks before being downregulated, while LHX6 gradually increased along with other markers enriched in pallial interneurons, including MAFB, MEF2C, and ERBB4 (Figs. 10B-10G). The percentage of cells expressing LHX8 increased up to ~40% during weeks 3 and 4, corresponding to progenitor expansion, corresponding to progenitor expansion, and then decreased as the cells upregulated LHX6 (Figs. 10D-10E). Implementation of a MEK pathway inhibitor during the MGE progenitor expansion phase was found to be crucial for promoting pallial interneuron development, as evidenced by the downregulation of LHX8 and upregulation of ERBB4 in the generated post-mitotic interneurons (Figs. 10H-10J). This effect was reproducible across independent cell batches, resulting in nearly all cells expressing LHX6 by the end of the differentiation process, of which ~80% co-expressed MAF/MAFB/ERBB4 and ~20% co-expressed LHX8 (Figs. 2B-2D, 10G; Table 1). The cholinergic marker ISL1 was expressed in up to 20% of cultured cells at Week 2, decreasing over time to less than 1% of cells by the week 6 (Figs. 2C, 2D,10D, 10E; Table 1). Other off- target markers, including the CGE marker SP8 and the hypothalamic/oligodendrocyte progenitor marker NKX2-2, were not detectable (Figs. 2D, 12D, 12E; Table 1). In summary, these immunocytochemistry (ICC) data are consistent with ~80% of the hESC-derived cells differentiating towards pallial MGE-type interneuron lineage (LHX6, MAF, MAFB, ERBB4- positive), and the remaining cells being subpallial MGE-type neurons (LHX6, LHX8 positive). Additional bioassays demonstrated that the differentiated neurons were GABAergic based on expression of GAD67 protein (93%+) and VGAT mRNA (81%+) (Table 1), as well as secretion of the neurotransmitter GABA, but not acetylcholine, into the culture supernatant (Figs. 2E, 2F). Although endogenous interneuron maturation occurs over a long period that extends postnatally, a subset of the hPSC-derived end-of-process interneurons had detectable mRNA expression of the subtype marker SST (37%) by week 6 (Table 1).
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mu snoi s s e r p x e r e k r a mw a h t t s o p s s e c o r p fod n E : 1 e l b a T [0256] Cells can be transplanted at a post-mitotic stage, rather than at a progenitor stage, to reduce or prevent potential proliferation and/or differentiation into off-target cell types. Previous transplantations of hPSC–derived GABAergic cells from the progenitor stage gave rise to mixed graft composition with residual cycling cells. Here NOTCH and CDK pathway inhibition was used to promote cell cycle exit and post-mitotic differentiation (Fig. 10A). In the absence of treatment, a significant proportion of cycling progenitors was still present at the end of the differentiation protocol. Upon NOTCHi, cycling progenitor cells were significantly depleted, which was further improved by the addition of CDKi (Figs. 11A- 11D). In addition, combined NOTCHi/CDKi treatment contributed to the downregulation of NKX2-1 and upregulation of on-target markers LHX6, MAF, and VGAT, consistent with differentiation towards the pallial MGE lineage (Figs. 11E, 11F). [0257] FIGs. 11A-11I: No residual proliferative progenitors or pluripotent stem cells identified in the end-of-process (week 6) samples. (FIGs. 11A-11C) Comparison of % KI67+ (FIG. 11A) and % 5-ethynyl-2’-deoxyuridine (EdU+) (FIGs. 11B, 11C) cells detected in unsorted cultures at the end-of-process without treatment (NT), versus NOTCH inhibition alone (NOTCHi), versus combined NOTCH and CDK4/6 inhibition (NOTCHi + CDKi) prior to cryopreservation. Biological replicates: NT n=19, NOTCHi n=26, NOTCHi+CdKi n=11. Data are expressed as a mean ± SEM. For (FIGs. 11B, 11C), two pulses of EdU were added to the culture during the last week of differentiation. (FIGs. 11D-11F) Effect of combined NOTCH and CDK4/6 inhibition on proliferating cells (Ki67) (FIGs. 11D, 11E), MGE progenitors NKX2-1, OLIG2 (FIG. 11E) and MGE (LHX6), pallial (MAF) and GABAergic (VGAT) markers (FIG. 11F) detected in end-of-process post cells after cryopreservation and thaw. Biological replicates: n=8 each group. Data are expressed as a mean ± SEM. (FIGs. 11G-11I) Representative evaluation of pluripotency markers (TRA-1- 60 and OCT4) by flow cytometry for in-process (week 2, FIG. 11G) and end-of-process (week 6, FIG. 11H) samples. (FIG. 11I) Experimentally-determined assay limits of detection (LOD) for the two time points. [0258] To achieve even higher purity of pallial-type interneurons, magnetic activated cell sorting (MACS) was performed using a biotinylated antibody against human ERBB4, a specific surface marker of migratory pallial interneurons. The percentage of LHX8+ cells was reduced from ~20% to <5% after sorting, while the proportion of pallial- type interneurons that co-expressed LHX6, MAF, and MAFB increased to >90% (Figs. 2C- 2E; Table 1). Interestingly, neither expression of GAD67 nor the amount of GABA detected in the culture supernatants were altered upon sorting (Table 1), suggesting that the main impurity population of LHX8-positive cells is also GABAergic. [0259] To facilitate clinical translation, efficient cryopreservation methods were developed to achieve high viability of post-mitotic interneurons after thawing (Fig. 2G). Quality control assays have been established to obtain consistent cell batches. For example, an assay to measure pluripotent stem cell markers POU5F1 (OCT4) and TRA-1-60 was developed using flow cytometry on in-process (week 2) and end-of-process (EOP, week 6) samples (Figs. 11G-11I). Analyzing post-thaw samples in triplicate (10 x 106 cells per sample), no pluripotent cells were detected above the limits of detection (LOD 0.002%, FIG. 11I). [0260] In addition, the migration potential of unsorted and sorted hESC-derived pallial MGE-type GABAergic interneurons was evaluated in vitro and compared to the migration of ERBB4-sorted human interneurons isolated from fetal MGE as well as two commercial sources of hPSC-derived GABAergic neuronal preparations (Figs. 12A-12C). While all the hPSC-derived GABAergic neurons expressed VGAT, only the pallial MGE- type interneurons expressed high levels of LHX6, MAFB, MAF, and ERBB4, and lacked expression of progenitor (OTX2), glial (GLAST), CGE (COUPTF2, SP8), and other off- target markers (ISL1, NKX2-2) (Figs. 12B, 12D, 12E). Furthermore, hESC-derived pallial MGE-type interneurons demonstrated migratory properties remarkably similar to endogenous human MGE interneurons in terms of morphology and extent of in vitro migration; this phenotype was not observed in the other types of GABAergic neurons (Figs. 12A-12C). These results indicate functional specificity of the in vitro migration assay, which is sensitive to the molecular identity of the cells. Taken together, these data provide evidence for specific, efficient, and reproducible generation of post-mitotic, migratory, pallial MGE-type GABAergic interneurons from human pluripotent stem cells. [0261] FIGs. 12A-12E: In vitro migration phenotypes of hESC-derived pallial MGE-like pallial interneurons compared to human endogenous MGE interneurons and commercially available hPSC-derived GABAergic cells. (FIG. 12A) In vitro migration assay was performed with human fetal MGE cells sorted for pallial interneuron surface marker (GW 18-20), hESC-derived pallial MGE-type interneurons (IN; unsorted and sorted) and two commercial sources of hPSC-derived GABAergic neurons. Cell identity was masked from the operator during assay set up and analyses. Phase contrast images were taken at the start of migration assay (Day 0, left most panel) and after three days. Higher magnification images show migrating cell morphology. (FIG. 12B) Aggregates were fixed after 3 days of migration and processed for ICC using antibodies against LHX6, MAFB and ERBB4. (FIG. 12C) Quantification of percent migrating cells after 3 days. Each dot is from a biological replicate and represents an average of 8-12 technical replicates. Data are expressed as a mean ± SEM. (FIGs. 12D, 12E) Marker expression by ICC comparing hESC-derived pallial GABAergic MGE-type interneurons prepared by a differentiation process discloses herein (left column) with two commercial sources of hPSC-derived GABAergic neurons. Key: “-” no detectable expression, “+” expressed in less than 10% of cells, “++” expressed in 10-50% of cells, “+++” expressed in 50-90% of cells, “++++” expressed in >90% of cells. [0262] In some embodiments, cortical inhibitory interneurons (including post- mitotic precursors thereof) suitable for use in methods of the present disclosure are differentiated in vitro from human embryonic stem cells (hESCs). In some embodiments, the differentiated cells are enriched for cells expressing on-target markers for post-mitotic GABAergic interneurons of an MGE-type cortical lineage compared to undifferentiated hESCs or MGE-type progenitor cells. In some embodiments, the differentiated cells are enriched for cells expressing at least LHX6 and ERBB4 compared to undifferentiated hESCs or MGE-type progenitor cells. In some embodiments, at least 90% of the differentiated cells express LHX6. In some embodiments, about 90% (or at least 75%) of the differentiated cells express ERBB4. In some embodiments, about 80% (or at least 75%) of the differentiated cells express MAF. In some embodiments, about 75% (or at least 50%) of the differentiated cells express MAFB. In some embodiments, at most 40% (or at most 30%) of the differentiated cells express LHX8. In some embodiments, about 50% (or 20-80%) of the differentiated cells express NKX2-1. In some embodiments, the differentiated cells are depleted of or substantially free of cells expressing off-target markers (including markers for mitotic precursor cells. In some embodiments, the differentiated cells are depleted of or substantially free of cells expressing OTX2, SP8, ISL1, NKX2.2, OLIG2, Ki67, and LHX8. In some embodiments, the differentiated cells are depleted of or substantially free of cells expressing markers for cell cycle (Ki67), pluripotency (POU5F1), glial cells (SLC1A3, OLIG2, GFAP), cholinergic neurons (SLC18A3), glutamatergic neurons (SLC17A7), dopaminergic neurons (TH) and/or serotonergic neurons (TPH1). In some embodiments, the differentiated cells are depleted of cells expressing markers for MGE-type progenitors (NKX2-1, VIM). Example 4 [0263] This non-limiting example shows that single cell RNAseq profiling confirms pallial MGE-type GABAergic interneuron identity. [0264] To objectively characterize cell composition during in vitro interneuron derivation, scRNA-seq was performed for three cell states: Day 0 hESCs prior to the start of differentiation, Day 14 MGE-type VZ-like neural progenitor cells (NPCs), and end-of- process (EOP, week 6) interneurons (several paired unsorted/sorted lots, including lots 1 and 2 used in the efficacy studies described below). All samples were previously cryopreserved and processed for sequencing post-thaw. Unbiased clustering analysis of all the cells based on global gene expression clearly separated cells by source and identified six distinct populations (clusters 0-5), representing different cell types and/or states (Figs. 3A, 3B). Undifferentiated Day 0 hESCs grouped tightly into a single cluster (Cluster 0), indicative of homogeneous gene expression in the starting hESC population (Figs. 3B, 3C). Pluripotency markers enriched in Cluster 0, including POU5F1 (OCT4) and NANOG, were not detected in the NPC-stage samples or the interneuron lots (Figs. 3D, 3E, 13A). Consistent with flow analyses (Figs. 4H, 4I), no residual pluripotent stem cells were identified in any of the interneuron lots, regardless of sorting (>85,000 end-stage cells profiled in this study) (Fig. 3C). [0265] FIGs. 3A-3E: Single cell RNA sequencing characterization of cell composition during in vitro differentiation and comparison with human developing GE dataset. scRNA-seq was performed on post-thaw cell preparations, including hESCs prior to the start of differentiation (Day 0), in-process MGE-type VZ-like progenitors (Day 14), and several paired (unsorted/sorted) end-of-process (week 6) interneuron lots, including lots 1 and 2. (FIGs. 3A, 3B) UMAP (Uniform Manifold Approximation and Projection) visualization of cell clusters in all the combined samples (FIG. 3A), and in each of the separate samples listed (FIG. 3B). (FIG. 3C) Quantification of sample composition by cluster. (FIG. 3D) Feature plot visualizations of gene expression across clusters 0-5. All cells are displayed in light gray, cells with detectable expression are displayed in purple, with darker shade corresponding to higher expression level. (FIG. 3E) Dot plot for key genes that define different cell categories, including general neuronal markers, GABAergic, GE neurons, MGE, pallial MGE interneurons, subpallial MGE, POA, CGE, LGE, neuronal progenitor markers (including MGE progenitor marker NKX2-1), cell cycle markers, pluripotent markers, as well as genes associated with glial cells, glutamatergic neurons (Glu), dopaminergic neurons (DA), serotonergic neurons (5HT) and cholinergic neurons (Ach). [0266] Day 14 progenitor samples were distributed across three clusters (Clusters 1/2/3) (Figs. 3A-3C). The two main clusters comprising 98.6% of NPCs (Cluster 1 – 86.7% and Cluster 2 – 11.9%) (Fig. 3C) are NKX2- 1+/FOXG1+ and likely represent different MGE precursor cell maturation states, as evidenced by the inverse gradients of neuronal and progenitor markers between these clusters. Namely, Cluster 1 had higher expression of NKX2-1 and the radial glia stem cell and neural progenitor markers VIM, NES, PTPRZ1 and FABP7, whereas Cluster 2 had higher expression of neuronal and GABAergic markers DCX, MAP2, GAD1/2 and DLX1/2/5 (Figs. 3D, 3E). These findings are consistent with a transition from ventricular zone MGE progenitors/radial glia to more mature secondary progenitors and/or newborn neurons. Thus, over 98% of the cells were specified into MGE-type NPCs after the patterning phase (Day 14). The remaining minor Day 14 Cluster (Cluster 3 – 1.4% of cells) appeared to contain off-target neuronal progenitor cells expressing markers such as VIM and NES. In addition, this cluster expressed some lateral ganglionic eminence (LGE) markers (EBF1, FOXP1, FOXP2, Fig. 3E) as well as markers characteristic of barrier- forming fibroblasts (LUM, COL1A2, DCN, Fig. 13A) that are present in the CNS and have been identified by other groups when profiling in vitro differentiated neuronal lineages. Importantly, no cells corresponding to Clusters 1/2/3 were identified in the EOP week-6 interneuron lots, regardless of sorting (Fig. 3C). This was also confirmed by the downregulation of MGE progenitor markers including NKX2-1, VIM, NES and PTPRZ1, and cell cycle associated markers such as MKI67, ASPM, CDK6, and CCND1 (Figs. 3D, 3E), confirming the post-mitotic stage of the derived interneurons. [0267] EOP week-6 cells were distributed between two main populations (Clusters 4 and 5) (Figs. 3B, 3C). Both clusters expressed high levels of the pan-MGE neuron markers LHX6 and SOX6, and additional neuronal (DCX, MAPT, MAP2), GABAergic (GAD1/2, SLC32A1 (VGAT)) and GE markers (DLX1/2/5, DLX6-AS1 (DLX2 co-activator), ARX and MEF2C) (Figs. 3D, 3E). However, Cluster 5 had higher expression of genes required for pallial MGE interneuron development and migration (ZEB2, MAF, MAFB, NXPH1, SST, CXCR4, ACKR3 (CXCR7) and ERBB4) compared to cluster 4 (Figs. 3D, 3E, 13A). For example, ZEB2 represses NKX2-1 expression and is required downstream of DLX1/2 to control the fate switch between striatal (subpallial) and cortical (pallial) interneurons. Thus, Cluster 5 was the intended on-target pallial MGE-type GABAergic interneuron population, representing 86% and 92% of cells in the unsorted lots 1 and 2, respectively (Figs. 3B, 3C). Over 99% of the cells from the sorted preparations of all sequenced lots corresponded to the on-target pallial MGE-type interneuron Cluster 5 (Figs. 3B, 3C). Cluster 4, in contrast, was characterized by co-expression of LHX6 with LHX8, lack of SST, and expression of other genes (including GBX2, ENC1, DNM3, NDN), consistent with subpallial MGE-type GABAergic projection neurons (Figs. 3D, 3E, 13A). Cluster 4 represented 14% and 8% of the population in the unsorted lots 1 and 2, respectively, and less than 1% of the population in the corresponding sorted lots (Figs. 3B, 3C). These results suggest that the main impurities in the unsorted lots are the closely-related MGE-type GABAergic subpallial neurons. [0268] FIGs. 13A-13D Single cell RNA sequencing gene expression patterns in vitro and in the developing human GE. scRNA-seq was performed on post-thaw cell preparations, including hESCs prior to the start of differentiation, Day 14 MGE-type VZ-like progenitors, and several paired (unsorted/sorted) end-of-process interneuron lots, including lots 1 and 2. (FIG. 13A) Dot plot showing top differentially expressed genes in each cluster. The size of the dot represents the fraction of positive cells in that cluster and the shade of the color represents average expression level. (FIGs. 13B, 13C) Violin plots showing expression of characteristic genes associated with different cell stages and cell types as listed, by sample (FIG. 13B) and by cluster (FIG. 13C). (FIG. 13D) UMAP visualization of human developing GE (GW9-18) scRNA-seq data from Shi et al., 2021. after processing the data to identify MGE, CGE and LGE clusters, as described in the original report. Feature plot visualizations of gene expression across the GE clusters, including markers of pallial MGE interneurons (LHX6, MAF, CXCR4; note: CXCR4 is also expressed by CGE-derived pallial interneurons), subpallial MGE (LHX8, NKX2-1), striatal MGE (CRABP1, ETV1), CGE (SCGN, CALB2), and LGE (MEIS2, FOXP1). [0269] Immature pallial interneurons ultimately further differentiate into transcriptionally heterogeneous subtypes, defined based on their expression of calcium- binding proteins (PV (PVALB), calbindin (CALB1) and calretinin (CALB2)) and neuropeptides (SST, NPY, VIP, CCK, and substance P (TAC1)). It has been shown that SST, NPY, and CCK expression begins in migrating immature interneurons during prenatal development. Thus, expression of these and other MGE- and CGE-derived pallial interneuron subtype markers was examined across samples and clusters (Figs. 13B, 13C). Among the MGE-derived markers, PVALB was not detected (Figs. 3B, 3C), consistent with its known late expression onset, but SST transcript was most abundant; in addition, there was expression of other interneuron markers (CALB1, NPY and RELN), particularly in the on- target end-of-process cluster 5. In contrast, no expression was detected of markers enriched in CGE-derived interneuron subtypes (CCK, VIP, HTR3A, CALB2, SP8, SCGN) (Figs. 13B, 13C, 3E). There was also no expression of other off-target markers, including ones associated with POA, LGE (striatal), glial cells, or other neuronal classes (Fig. 3E). Collectively, these findings provided unbiased global transcriptomic validation for highly specific derivation of post-mitotic, pallial MGE-type GABAergic interneurons. [0270] To further evaluate in vitro-derived cell identity, the Day 14 and week 6 EOP single-cell gene expression data were compared with a single nuclei RNAseq dataset from the human GE (gestational weeks GW9-18) (Shi et al., 2021, Mouse and human share conserved transcriptional programs for interneuron development. Science (New York, N.Y.), 374(6573), eabj6641). The Shi et al. study captured several post-mitotic MGE populations, including a prominent pallial MGE cluster (FIG. 13D: LHX6+, MAF+, CXCR4+), a subpallial MGE cluster (FIG. 13D: LHX6+, LHX8+, NKX2-1+) and a striatal MGE-derived interneuron cluster (FIG. 13D: LHX6+, CRABP1+, ETV1+). In addition, this dataset included GE progenitors, as well as post-mitotic CGE (FIG. 13D: SCGN+, CALB2+) and LGE (FIG. 13D: MEIS2+, FOXP1+) populations. A prediction analysis was performed, where a score between 0 and 1 was assigned to each in vitro-derived cell based on the transcriptome-wide similarity in gene expression between the query (in vitro cells) and the reference (in vivo clusters belonging to the different human GE populations). These independent analyses demonstrated that all the end-of-process cells correspond to MGE identity (FIG. 3F), with cells in Cluster 5 having very high prediction scores for pallial MGE- derived interneurons, and cells in Cluster 4 having high prediction scores for subpallial MGE-derived projection neurons (Figs. 3F, 3G). In contrast, Day 14 progenitors had high prediction scores for human GE progenitors, and not the post-mitotic MGE populations (Figs. 3F, 3G). No cells that were similar to the “striatal” MGE population in the Shi et al. dataset were identified. Some of the Cluster 4 cells had a weak prediction score for LGE, which is likely due to a shared transcriptional program between the two regions. Importantly, none of the cells had strong prediction scores for CGE (Figs. 3F, 3G), consistent with lack of CGE marker expression. [0271] FIGs. 3F, 3G: Comparison of in vitro-derived Day 14 MGE-like progenitors and end-of-process interneurons with human developing GE (GW9-18), using the Shi et al., 2021 dataset as a reference. (FIG. 3F) Prediction scores between 0 and 1 are projected onto day 14 and end-of-process clusters. Each in vitro-derived cell was assigned a prediction score based on the transcriptomic similarity between the query (in vitro cells) and the listed reference GE cell type. (FIG. 3G) Heatmap showing percentage of cells in each in vitro cluster that are assigned to different GE categories based on prediction scores. Example 5 [0272] This non-limiting example shows human ESC-derived pallial MGE-type interneurons persist long-term and functionally integrate in the wild-type and epileptic rodent pallium. [0273] Sorted MGE-type interneurons were transplanted into the postnatal mouse brain to characterize their electrophysiological properties within the rodent pallium. Prior to transplantation, cells were virally labeled using a lentivirus expressing either GFP under the control of the human ubiquitin promoter (UBC) (Figs. 4A-4Q, 4U-4W) or channelrhodopsin (ChR2)-YFP under the control of the synapsin (SYN) promoter (Figs. 4T, 4X-4Z). In the first set of experiments, GFP-labeled cells were injected bilaterally into the neocortex of postnatal day (P)0-2 mice. Histological assessment of the transplants was performed 2.5 and 5.5 months post-transplant (MPT) (Figs. 4A, 4B). From 2.5 to 5.5 MPT, HNMA-positive human cells displayed an increasing number of branches (Fig. 4A) and maintained LHX6 expression (Fig. 4B), thus confirming a human MGE neuronal lineage. [0274] FIGS. 4A-4Z: Electrophysiological characterization of grafted human interneurons in the rodent pallium. (FIG. 4A) Cell morphology of GFP-labeled human cells at 2.5 and 5.5 months post transplant (MPT) in the wild-type (WT) mouse cortex. (FIG. 4B) IHC staining with HNMA and LHX6 confirming the human origin and MGE identity of GFP+ cells. (FIG. 4C) Upon recording, cells were backfilled with biocytin and co-stained for GFP and HNA. (FIGs. 4D-4Q) Whole cell patch-clamp recordings in acute brain slices were performed at 4 and 7.5 MPT. A total of n=5 cells from each time point were validated by staining. Examples of action potentials (AP) recorded from transplanted human interneurons at 4.5 (FIG. 4D) and 7.5 (FIG. 4E) MPT. (FIGs. 4F-4M) Physiological properties, including membrane resistance (FIG. 4F), capacitance (FIG. 4G), resting membrane potential (FIG. 4H), peak intensities for sodium (Na+) and potassium (K+) currents (FIG. 4I), maximum AP firing rate (FIG. 4J), maximum AP amplitude (FIG. 4K), AP width (FIG. 4L) and the threshold to spike (FIG. 4M) were evaluated. (FIG. 4N) Example of an inward current detected at -60mV in the majority of the recorded human cells (n=4 out of 5 cells for both time points), which was blocked by NBQX, indicating glutamate–mediated spontaneous excitatory postsynaptic currents (sEPSCs). (FIG. 4O) Average sEPSC frequency (n=4 each). (P,Q) Individual spike amplitudes (FIG. 4P) and inter-spike intervals (FIG. 4Q) recorded from the human cells at 4 and 7.5 MPT. (FIGs. 4R, 4S) Examples of human interneurons firing evoked aPs at ~15 MPT in the WT cortex (FIG. 4R) and in the hippocampus (HC, FIG. 4S). (FIG. 4T) IHC staining of SYN-ChR2-YFP labeled human cells in the epileptic HC ~15 MPT: ChR2-YFP, HNA and LHX6. Regions 1 and 2 are shown at higher magnification with arrows pointing out examples of human cells (HNA+ LHX6+). (FIGs. 4U-4W) Analysis of sEPSCs detected in the majority of human cells at ~15 MPT in the WT CTX (n = 8 out of 10 recorded) and epileptic HC (n = 4 out of 5 recorded). (FIG. 4U) Average sEPSC frequency, (FIG. 4V) Individual sEPSC amplitudes, and (FIG. 4W) Inter-event intervals. (FIGs. 4X-4Z) Blue light stimulation was used to induce inward currents in ChR2-expressing human cells (FIG. 4X), leading to evoked inhibitory postsynaptic currents (eIPSC) that were measured from the host mouse neurons (FIG. 4Y). (FIG. 4Z) Average eIPSC amplitudes recorded from mouse neurons following blue light stimulation in the WT CTX (n = 5 out of 23 recorded cells, ~17 MPT) and in the epileptic HC (n = 2 out of 4 recorded cells, ~16 MPT). Throughout the figure, significant differences are indicated by asterisks (* P<0.05; ** P<0.01; **** P<0.0001), Mann-Whitney test. [0275] The electrophysiological properties of the transplanted cells were analyzed at 4 and 7.5 MPT. Human cells were identified based on GFP expression in acute recipient mouse brain slices. Upon recording, cells were backfilled with biocytin and co-stained with HNA to validate their human origin (Fig. 4C). A total of n=5 validated human cells were recorded at each time point. All recorded cells fired action potentials (AP) (Figs. 4D, 4E), with 60% and 80% exhibiting spontaneous firing at 4 and 7.5 MPT, respectively. At 7.5 MPT, cells displayed significantly lower mean membrane resistance than at 4 MPT (Fig. 4F, p=0.0317) and higher mean membrane capacitance (Fig. 4G, p=0.0079), indicative of continued maturation; these values are on par with previously-reported values at 10 MPT for in vitro-derived GABAergic cells. However, the relatively elevated resting membrane potentials (~ -50mV) and time constant values (Fig. 4H) indicated that recorded cells were still immature at 7.5 MPT. [0276] Upon voltage pulse application, transplanted cells displayed rapid inward and sustained outward currents, indicative of voltage-gated Na+ and K+ channels. An increase in peak K+ currents was observed between 4 MPT and 7.5 MPT (Fig. 4I). AP properties also indicated a slightly more mature phenotype at 7.5 MPT than at 4 MPT, with a noticeable increase in maximum firing frequency (Figs. 4D, 4E, 4J), significantly higher mean AP amplitude (Fig. 4K, p=0.0317), and a tendency towards decreased mean AP duration and threshold (Figs. 4L, 4M). Importantly, 80-100% of human interneurons (at least 4 out 5 at both time points) exhibited inward currents with fast decay kinetics when holding the voltage at -60mV (Figs. 4N-4Q), which were blocked by the AMPA receptor antagonist NBQX (Fig. 4N), indicating that grafted cells were synaptically connected and received glutamate-mediated spontaneous excitatory postsynaptic currents (sEPSCs). [0277] Whether human pallial MGE-type interneurons could survive long-term (approximately 15 MPT) and form functional synapses, not only in the wild-type cortex (WT CTX) but also in the epileptic hippocampus (HC), was assessed. All human cells recorded in the CTX (n=11) (Fig. 4R) and in the HC (n=5) (Fig. 4S) fired APs. (ChR2)-YFP-expressing human MGE-type interneurons were found in abundance with extensive processes covering the entire epileptic HC (Fig. 4T). At these late time points, 80% of transplanted cells in both the WT CTX (8 out of 10) and epileptic HC (4 out of 5) exhibited sEPSCs (Figs. 4U-4W). Furthermore, upon blue light stimulation, ChR2-expressing human interneurons showed fast inward currents (Fig. 4X), and endogenous mouse neurons could be identified in both the WT CTX (5 out of 23 recorded) and the epileptic HC (2 out of 4 recorded) with light-evoked inhibitory postsynaptic currents (eIPSCs) (Figs. 4Y, 4Z). Collectively, these results demonstrate that in vitro-derived human pallial MGE-type interneurons can persist long- term, functionally integrate into the rodent pallium, and establish inhibitory synapses onto host neurons in the epileptic hippocampus. Example 6 [0278] This non-limiting example shows that human ESC-derived pallial MGE- type interneurons significantly suppress seizures in the MTLE mouse model. [0279] Immunodeficient NOG mice received an intrahippocampal injection of kainate into the dorsal CA1 region, which induced status epilepticus followed by the development of chronic spontaneous recurrent mesiotemporal seizures. In this chronic phase, approximately one month after kainate injection, two independent surgeries were conducted to transplant the cells and implant an EEG electrode into the epileptic hippocampus (Figs. 5A, 14A, 14B). In this model of MTLE, animals displayed a typical sclerotic hippocampal pathology, including granule cell dispersion ipsilateral to the kainate injection (Fig. 14B), and had electrographic mesiotemporal seizures at a frequency of 10-15 per 30-minute period (Fig. 14C). Several studies in this model have shown that mesiotemporal seizures are resistant to commonly prescribed first-line ASDs, such as carbamazepine and levetiracetam. Baseline seizures were detected by intrahippocampal EEG recordings over multiple days at 1 week and 1-2 MPT (Fig. 14C). [0280] FIGs. 5A-5H: Overview of the chronic MTLE mouse model and seizure suppression after cell transplantation with interneuron lots 1U and 1S. (FIG. 5A) Experimental timeline from epilepsy induction to cell transplantation, electrode implantation, EEG recordings, behavioral assays, and histological analyses. (FIGs. 5B-5H) EEG was recorded at the indicated time points post-transplant to detect electrographic seizure frequency and duration. Typical electrographic seizure phenotypes in chronically epileptic mice at 6 weeks post transplant (WPT), 5 and 7 MPT after vehicle (FIG. 5B) or cell injection (FIG. 5C). (FIG. 5D) Normalized electrographic mesiotemporal seizure frequency for epileptic animals treated with lots 1-U and 1-S. The mean seizure frequency of the vehicle control group is normalized to zero at each respective time point. The individual vehicle or cell-treated animals are plotted as a percent difference from the mean seizure frequency of the respective vehicle control group at 1-2, 5, and 7 MPT. A responder-rate threshold was designated for animals exhibiting >75% reduction in seizure frequency (depicted dashed line). Mann-Whitney test cell vs. vehicle at respective time point; significant differences are indicated by red asterisks (* P<0.05; ** P<0.01; *** P<0.001). Bar graphs represent median and dots correspond to individual animals. (FIGs. 5E, 5F) Raw data corresponding to FIG. 5D. Cumulative duration of seizures (FIG. 5E) and electrographic seizure frequency (FIG. 5F). Mann-Whitney test cell vs. vehicle at respective time point; significant differences are indicated by red asterisks (* P<0.05; ** P<0.01; *** P<0.001). In addition, significant changes within a treatment group vs. its own baseline are indicated by hashtags (Kruskal Wallis test followed by Dunn’s; #P<0.05; ## P<0.01; ### P<0.001). Number of animals analyzed per group (n= 8-16). (FIGs. 5G, 5H) Human cells (HNA+) migrated and dispersed throughout the hippocampus. Expression of interneuron subtype marker Somatostatin (SST) (FIG. 5G) and neuronal marker MAP2 (FIG. 5H) is shown at 8.5MPT. [0281] FIGs. 14A-14H: Reproducible seizure suppression achieved with multiple independent cell lots. (FIGs. 14A, 14B) Representative images of mice hippocampi, highlighting targeting strategy for three independent surgical procedures. (FIG. 14A) Naive mice were injected with kainate into the rostral right hippocampus (CA1) to induce status epilepticus (SE). Kainate injection site indicated by the yellow target. (FIG. 14B) Human interneurons, or a vehicle control, were administered throughout the hippocampus in 4-6 deposit sites (targeted coordinates highlighted by blue dots over the H&E stained hippocampal sections at 1 month post status epilepticus. Site of electrode placement is indicated by an arrow. (FIG. 14C) By 1 month after SE, mice developed spontaneous recurrent seizures. Baseline seizure frequency was stable between vehicle and cell-treated mice directly after transplantation until 2 MPT. (FIGs. 14D, 14E) Additional sorted lots (lots 3-5) were assessed in the MTLE model at a dose of 200K cells/hippocampus. The mean seizure frequency (FIG. 14D) and cumulative seizure duration (FIG. 14E) of the vehicle control group is normalized to zero at each respective time point. The individual cell- treated animals are plotted as a percent difference in seizure frequency from the respective vehicle control group mean at 1-9 MPT. A responder-rate threshold was designated for animals exhibiting >75% reduction in seizure frequency (depicted as dashed line). All data are median and show spread of individual animals. Mann-Whitney test cell vs. vehicle at respective time point; significant differences are indicated by asterisk (P<0.05). Responder rates are provided for animals that received each of the cell lots. (FIG. 14F) Human cells stained for HNA and SST in the epileptic hippocampus (xxx mark the approximate anterior- posterior (AP) positions of the transplants and a-d mark the approximate AP coordinates of the images shown) as shown here at 8.5 MPT. (FIG. 14G) Grafted human cells were analyzed by fluorescence in situ hybridization (FISH) using probes against the human housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (hGADPH) and the GABAergic marker glutamate decarboxylase 1 (GAD1). Representative images show cell distribution in the hippocampus with higher magnification examples of the CA1 and CA3 regions. (FIG. 14H) Images of the hippocampus stained for Vimentin (VIM) and HNA. [0282] Cryopreserved hESC-derived pallial MGE-type interneurons were thawed and transplanted along the rostrocaudal axis of the hippocampus in multiple deposit sites (Figs. 5A, 14B). Lot 1 unsorted (1-U) and sorted (1-S) batches (Figs. 3A-3G) were evaluated for seizure-modifying activity at 1-2, 5 and 7 MPT. All treatment groups had comparable seizure frequency and cumulative seizure duration at the beginning of the study, 1-2 MPT (Figs. 5D-5F). While the control group exhibited a moderate decrease in seizure frequency over time, cumulative seizure duration was not reduced between 1-2 and 7 MPT (Fig. 5E), and none of the vehicle-treated animals became seizure-free (Fig. 5F). In contrast, most of the cell-treated epileptic animals became mesiotemporal seizure-free by 5 MPT and remained seizure-free for the duration of the study, with significantly reduced cumulative seizure duration (Fig. 5D-5F). The significant reduction in seizure activity was observed with both unsorted and sorted interneuron lots. [0283] The cell transplant-mediated seizure suppression was reproducible in multiple studies using independently manufactured human pallial MGE-type interneuron cell lots (Figs. 14D, 14E). Across five different sorted lots at the same dose (200K cells/hippocampus), 72% (48/67) of the cell-transplanted animals responded with >75% reduction in seizure frequency, and 59% (40/67) of the cell-transplanted animals became seizure-free by 6-7 MPT (Figs. 5D, 5F, 7A, 14D). The seizure-suppressing effect was stable for the duration of the longest studies, which went up to 9 MPT (Fig. 14D). In addition, cumulative seizure duration was significantly lower in animals receiving the interneuron cell lots (Figs. 5E, 14E). [0284] In some embodiments, administering hESC-derived, pallial, MGE-type inhibitory interneuron cells to a subject having seizure activity substantially abolishes seizures in the subject. In some embodiments, administering the pallial MGE-type inhibitory interneuron cells to a subject having seizure activity reduces seizure frequency by at least about 75% compared to vehicle control. In some embodiments, administering the pallial MGE-type inhibitory interneuron cells to a subject having seizure activity reduces seizure frequency by at least about 75% in at least 60% of the subjects compared to vehicle control. In some embodiments, reduction in seizure frequency after administering the pallial MGE- type inhibitory interneuron cells is observed at least 5-7 months after the administering. In some embodiments, administering a dose of about 200,000 cells per subject delivered ipsilateral to the focal onset seizure reduces seizure frequency or abolishes seizures in the subject. [0285] In some embodiments, a subject in need of treatment for seizure activity has a hippocampal pathology associated with spontaneous, recurrent seizures. In some embodiments, a subject in need of treatment for seizure activity has chronic epilepsy. In some embodiments, a subject in need of treatment for seizure activity has a focal onset seizure. In some embodiments, a method of treating seizure activity comprises administering a therapeutically effective amount of hESC-derived pallial MGE-type inhibitory interneuron cells to one or more sites in the subject’s hippocampus and/or cortex. In some embodiments, a method of treating seizure activity comprises administering a therapeutically effective amount of hESC-derived pallial MGE-type inhibitory interneuron cells to 1, 2, 3, 4, 5, 6, or more sites in the subject’s hippocampus and/or cortex. Example 7 [0286] This non-limiting example shows human ESC-derived interneurons disperse, innervate the epileptic hippocampus, and express subtype markers of pallial MGE- type GABAergic interneurons. [0287] Time course analysis at 1, 4 and 8.5 MPT revealed intrahippocampal migration of the transplanted cells by 1 MPT, followed by DCX downregulation between 1 and 4 MPT, and gradual SST upregulation from 4 to 8.5 MPT (Figs. 6A, 6B, 5G). At the end of the study, virtually all the human cells were MAP2 positive (Fig. 5H), migrated >0.9 mm away from the injection sites, and filled the hilus of the dentate gyrus, extending into the pyramidal cell layers and subiculum along the rostrocaudal and dorsoventral axes (Fig. 6C). Cell clusters or cores were not observed near the injection sites or elsewhere (Figs. 4T, 5G, 5H, 6A-6E, 7B-7D, 14F-14H). [0288] At the end of the studies, human cell persistence and fate in the epileptic hippocampus were evaluated. Of the 200K human cells (lots 1-U and 1-S) injected per hippocampus, 9K-12K (4.5-6%) persisted at 8.5 MPT (Fig. 6F). In situ hybridization (ISH) analysis demonstrated that 98-100% of the human cells throughout the hippocampus expressed GAD1 mRNA, confirming their GABAergic identity (Figs. 6D, 14G). In addition, the majority of human cells were positive for LHX6 (80-95%) (Figs. 6E (panel i), 6G), and approximately 30-55% had detectable SST expression by IHC (Figs. 6E (panel ii), 6G). A fraction of the SST+ cells co-expressed NPY (Fig. 6E (panel iii)). PV expression was rare (<1% of human cells, Fig. 6E (panel iv)), which is consistent with the protracted development of endogenous PV interneurons. However, some of the human SST-negative cells expressed WFA Fig. 6E (panel v), a marker of perineuronal nets (PNNs), which are extracellular matrix structures found primarily on fast-spiking PV+ interneurons, providing proof-of-concept evidence that some human interneurons with properties of PV cells may be generated from the grafted human MGE-type pallial interneurons. Calbindin staining was not detected in human cells (Fig. 8L). No significant expression of off-target markers was observed, including CGE interneuron markers SP8 and calretinin Fig. 6E (panel vi). MGE progenitor and glial marker OLIG2 was not detected (Figs. 6E (panel vii), 6G). Astrocyte marker GFAP was very rarely observed along the injection tract and never among the dispersed cells, contributing to less than 0.01% of grafted human cells (Figs. 6E (panel viii), 6G). Similarly, virtually no proliferating KI67+ cells were detected (Figs. 6E (panel ix), 6G). Neural stem cell and astrocyte marker Vimentin (VIM) was detected in the vehicle-treated ipsilateral hippocampus (Fig. 14H), likely labeling endogenous reactive astrocytes. Interestingly, VIM staining was markedly reduced in the cell-treated epileptic hippocampus, and VIM was not expressed by the human cells (Fig. 14H), further confirming the lack of neural progenitors from the graft. Collectively, these results are consistent with in vitro data and demonstrate that the hESC-derived interneurons differentiate into pallial MGE-type GABAergic interneuron subtypes in vivo and do not exhibit continued neurogenesis or proliferation after transplantation. Critically, no teratomas or ectopic tissues were ever observed upon inspection of hematoxylin and eosin (H&E)-stained brain sections from a complete rostrocaudal review of every 12th 40 μm tissue section of every animal. [0289] FIGs. 6A-6M: Histological characterization of interneuron lots 1-U and 1-S in the epileptic hippocampus. (FIGs. 6A, 6B) Expression of immature neuronal marker doublecortin (DCX) (FIG. 6A) and MGE interneuron marker somatostatin (SST) (FIG. 6B) in human cells (HNA) at 1, 4 and 8.5 MPT. (FIG. 6C) Human-specific axonal marker hTAU showing transplanted cell processes in the rostral to caudal epileptic HC (panels a-d), counter-stained with NEUN. (FIG. 6D) Grafted human cells were analyzed by fluorescence in situ hybridization (FISH) using probes against the human housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (hGADPH) and the GABAergic marker glutamate decarboxylase 1 (GAD1). Representative image shows cell distribution in the rostral hippocampus with a higher magnification example of the hilus (1). (FIG. 6E) Representative IHC images showing co-labeling of human cells (HNA+) with on-target MGE interneuron markers in green: LHX6, SST, NPY, PV as well as perineuronal nets marker WFA associated with fast spiking PV-type interneurons. Arrowheads point to specific examples of human cells expressing the markers of interest. Off-target populations, including markers for non-MGE lineage interneurons (Calretinin, CR,), oligodendrocytes (OLIG2), astrocytes (hGFAP), proliferating cells (KI67) and neural stem cells/progenitors/astrocytes (Vimentin, VIM) are shown in cyan. (FIGs. 6F, 6G) Quantification of human cell persistence (FIG. 6F) and percent of human cells expressing GAD1 mRNA, and LHX6, SST, KI67, OLIG2 and GFAP proteins (FIG. 6G). [0290] In some embodiments, the hESC-derived, differentiated cells are enriched for cells expressing at least LHX6, ERBB4, and GAD1 compared to undifferentiated hESCs or MGE-type progenitor cells. In some embodiments, at least 98% of the differentiated cells express GAD1. Example 8 [0291] This non-limiting example shows that human pallial MGE-type interneurons demonstrate dose-dependent seizure suppression. [0292] To help define the efficacious dosing range, lot 2 unsorted (2-U) and sorted (2-S) cells (Figs. 3A-3G) were evaluated across a series of doses: lot 2-U at 25K, 50K, 200K, and 1.5M cells per hippocampus, and lot 2-S at the two highest doses only. The escalating cell dose treatment cohorts had separate vehicle control groups (Low/Mid/High) to match larger delivery volumes. Examining the full range of doses with lot 2-U, mesiotemporal seizure frequency was suppressed in a dose-dependent manner. While 25K and 50K cell doses did not significantly reduce mean seizure frequency, statistically significant seizure suppression was achieved with 200K and 1.5M cell doses at 7 MPT (Fig. 7A). Of note, 17% of animals with 25K cell dose and 44% of animals with 50K cell dose, respectively, displayed >75% seizure suppression, suggesting partial efficacy at the 50K dose. With the highest dose of 1.5M, 89% (8/9) of animals transplanted with lot 2-U and 100% (15/15) of animals transplanted with lot 2-S were seizure-free at 7 MPT (Fig. 7A). These results indicate a wide efficacious dosing range for the pallial MGE-type GABAergic interneurons. Histological analyses confirmed that the two higher doses filled the hippocampus more extensively, as expected (Figs. 7B, 7E). The relative human cell persistence was comparable in the range of 25K to 200K doses, averaging 7-10% of the initial dose (Fig. 7H). However, with the 1.5M dose, the relative persistence was notably lower at <2% of the initial dose (Fig. 7H), suggesting a possible plateau in the maximum cell number that could be maintained in the host hippocampus. Similar to lot 1 cells, most of the persisting lot 2 cells were LHX6+ (80-90%) across doses (Figs. 7C, 7F, 7I), and ~20-30% had detectable SST expression (Fig. 7D, 7G, 7J). Moreover, proliferating/progenitor markers OLIG2, GFAP, and KI67 were below 0.01% for both unsorted and sorted lot 2 transplants. [0293] FIGs. 7A-7J: Human interneuron dose-response activity in the MTLE model. (FIG. 7A) Four doses of hESC-derived interneurons (lot 2-U) were transplanted into the MTLE mouse model: 25K, 50K, 200K or 1.5M cells/hippocampus. The two higher doses were also evaluated with sorted cells (lot 2-S). Vehicle group mean seizure frequency is normalized to zero. The escalating cell dose treatment cohorts had separate vehicle control groups to match larger delivery volumes. All data are median and single dots indicate individual animals. Significant differences between cell vs. vehicle groups at each time point are indicated by asterisk (P<0.05), Mann-Whitney test (200K and 1.5M dose groups vs. respective vehicle groups). Kruskal Wallis test between 25K and 50K vs. corresponding vehicle group was not significant at any of the time points. A responder-rate threshold was designated for animals exhibiting >75% reduction in seizure frequency (depicted as red, dashed line). (FIGs. 7B-7D) Histology panel shows cell persistence, distribution, and fate in the epileptic hippocampus at the four doses of human interneurons from lot 2-U at 8.5 MPT. (FIG. 7B) Immunohistochemical detection of persisting HNA+ human cells. (FIGs. 7C, 7D) Higher magnification images of the corresponding dentate gyrus. Persisting human cells expressed MGE interneuron markers LHX6 (FIG. 7C) and SST (FIG. 7D). (FIGs. 7E-7J) Quantification of human cell persistence and fate of lots 2-U and 2-S. The total number of persisting human cells at 8.5 MPT and rate of persistence as a percentage of the initial dose. (FIGs. 7F-7I) Quantification of the total number of LHX6+ human cells and the percentage of human cells expressing HNA (FIG. 7E), LHX6 (FIG. 7F) and SST (FIG. 7G) at 8.5 MPT. (FIG. 7H) The rate of human cell persistence as a percentage of HNA over the initial dose. (FIGs. 7I, 7J) Quantification of LHX6 (FIG. 7I) and SST (FIG. 7J) out of the total persisting human cells (= HNA). [0294] In some embodiments, suppression of seizure by administering hESC- derived pallial MGE-type inhibitory (e.g., GABAergic) interneuron cells to a subject having seizure activity is dose dependent. In some embodiments, at least about 60%, or on average about 80% of persistent cells in the transplanted hippocampus to which hESC-derived pallial MGE-type inhibitory (e.g., GABAergic) interneuron cells were transplanted are MGE-type GABAergic interneurons. In some embodiments, at least about 5%, or on average about 20- 55% of persistent cells in the hippocampus to which hESC-derived pallial MGE-type inhibitory (e.g., GABAergic) interneuron cells were transplanted are cortical interneurons expressing SST. Example 9 [0295] This non-limiting example shows Human pallial MGE-type interneuron transplantation reduces dentate granule cell dispersion in the epileptic hippocampus. [0296] One hallmark of MTLE is the characteristic sclerotic pathology of the affected hippocampus. The intrahippocampal kainate mouse model recapitulates sclerotic hippocampal dentate granule cell (GC) dispersion and the overall neurodegeneration seen in patients. To quantitatively assess the effects of cell transplantation on GC dispersion, the width and the area of the GC layer were measured in the rostral hippocampus of naive mice, vehicle-treated epileptic mice, and cell-treated epileptic mice that received different doses of lots 2-U and 2-S (Figs. 8A-8H). All cell doses significantly reduced GC layer width compared to vehicle treatment (Fig. 8G). There was also a dose-dependent effect on the GC layer area, with more significant reduction observed at the two higher doses (Fig. 8H). There were no differences in the GC measurements between animals that received unsorted or sorted cell batches, nor between animal groups that received different vehicle volumes (Figs. 8G, 8H). IHC analysis showed NEUN and CALB positive endogenous cells and confirmed reduced GC dispersion in the cell-treated hippocampus. Histological analysis of cleaved caspase 3 (cl-CASP3) demonstrated host cell death in the CA1 and CA3 subfields of the epileptic hippocampus that was not noticeably different in cell or vehicle treated animals (Figs. 8I-8L). The reduced GC dispersion observed in the cell-treated animals was not accompanied by an increase in cl-CASP3 labeling, indicating that interneuron transplantation did not induce granule cell death. [0297] FIGs. 8A-8L: Epileptic hippocampal pathology, behavioral outcome and animal survival after human interneuron transplantation. (FIGs. 8A-8H) Granule Cell Dispersion Analysis: DAPI labeling shows the granule cell (GC) layer in an age- matched naive mouse (FIG. 8A), epileptic vehicle-treated mouse with typical pathological GC dispersion at 8.5 MPT (FIG. 8B) and epileptic cell-treated mice transplanted with 25K, 50K, 200K and 1.5M human cells/hippocampus of lot 2-U, respectively (FIGs. 8C-8F) at 8.5 MPT. (FIGs. 8G, 8H) GC dispersion was quantified by measurements at -1.8 mm from Bregma, which is the rostrocaudal level of the kainate injection: the average GC layer width (FIG. 8H) was measured at three places, as illustrated with white lines in B, and GC layer area (FIG. 8H) was measured as illustrated with a white boundary in FIG. 8B. All data are mean ± SEM. Three vehicle groups were used to match the delivery volumes of the respective cell doses, labeled as Vehicle-Low, Vehicle-Mid and Vehicle-High. The Kruskal Wallis statistic, followed by Dunn’s test, was significant between cell and vehicle groups at all doses for both lots, 2-U and 2-S (P<0.05). (FIGs. 8I, 8J) Apoptotic cell labeling with cleaved Caspase 3 (Casp3, white) in vehicle (FIG. 8I) or cell-treated (FIG. 8J) mice. (FIGs. 8K, 8L) IHC staining for endogenous Calbindin-expressing neurons in the GC layer of vehicle (FIG. 8K) or cell-treated (FIG. 8L) mice. [0298] In some embodiments, a subject having seizure activity exhibits an epileptic hippocampal pathology. In some embodiments, a subject having seizure activity exhibits an increase in the width or area of the granule cell layer at the level of the epileptogenic lesion. In some embodiments, a subject having seizure activity exhibits an increase in granule cell dispersion at the level of the hippocampal sclerosis. In some embodiments, administering hESC-derived pallial MGE-type inhibitory (e.g., GABAergic) interneuron cells to a subject having seizure activity reduces the width or area of the granule cell layer at the level of the hippocampal sclerosis. In some embodiments, administering hESC-derived pallial MGE-type inhibitory (e.g., GABAergic) interneuron cells to a subject having seizure activity reduces granule cell dispersion at the level of the hippocampal sclerosis. Example 10 [0299] This non-limiting example shows that improved spatial memory, increased epileptic animal survival, and no adverse effects are detected after human pallial MGE-type interneuron transplantation. [0300] Dizziness, sedation, and ataxia are the most common adverse effects of systemically administered GABA-potentiating ASDs. It is possible that increasing neural network inhibition by transplanting high doses of GABAergic interneurons could lead to sedative effects as well. Therefore, a modified Irwin screen was performed to evaluate potential adverse effects of cell treatment with the highest dose (1.5M/hippocampus) of lot 2- U cells in epileptic mice. The testing battery included assays for body posture and appearance, excitability, and spatial locomotion (Fig. 8M). Cell-transplanted epileptic mice did not show any adverse effects or behave differently than vehicle-treated epileptic mice in any of the testing paradigms. Similar results were found in epileptic mice transplanted with sorted cells and lower doses. In some paradigms, such as anxiety-related behavior in the open field arena, the behavioral pathology of the intrahippocampal kainate model did not differ from naive mice, thus it would not be possible to detect any behavioral improvement after transplantation (Fig. 8N). Since sedative effects of cell therapy could also lead to less activity and consequently less time in the center of the open field, the velocity of running was also tested: epileptic vehicle-treated mice ran significantly faster than naive mice, which can be attributed to their hyperexcitability and hyperactivity. Activity levels of cell-transplanted mice were not different from naive mice in this assay (Fig. 8N). The preference for left rotations in the Y-maze test (Fig. 8O) was seen in control and transplanted animals, and is likely a result of the unilateral kainate injection. In summary, none of the cell doses and lots tested, including the highest dose of 1.5M unsorted human GABAergic interneurons per hippocampus, caused behavioral abnormalities compared to vehicle-treated animals. [0301] FIGs. 8M-8Q: (FIG. 8M) A modified Irwin screen was performed to evaluate potential side effects of human GABAergic interneuron administration. Data are only shown for the highest tested dose of 1.5 M cells/hippocampus of lot 2-U. All data are expressed as median with interquartile range. Mann Whitney test for differences between cell and vehicle groups; significant differences are indicated by asterisk (P<0.05). (FIG. 8N) An Open Field (OF) test was performed to measure general anxiety, spatial locomotion and travel velocity. (FIG. 8O) Y maze test was performed to measure spatial memory. (FIG. 8P) Barnes maze was performed to assess learning and memory with a mid cell dose only (200K) using naive mice (blue, N=13), epileptic vehicle-injected mice (black, N=11) and epileptic cell-transplanted mice (N=13). (FIG. 8Q) Survival curves for epileptic animals treated with either vehicle (black), or transplanted with unsorted (200K, Lots 1-U/2-U, light gray, N=47) or sorted (200K, Lots 1-S/2-S dark gray, N=52). Significantly longer survival at 200 days post-transplant (DPT) was observed with both unsorted and sorted cell lots compared to vehicle treatment (Chi-square test performed , P<0.05). [0302] One of the comorbidities of drug-resistant epilepsy, and a primary adverse effect of temporal lobe resection/ablation surgery, is impaired learning and memory. Cell- transplanted epileptic mice learned faster in a spatial memory test compared to vehicle- treated mice, and at a similar rate as naive controls (Fig. 8P). [0303] In chronic experimental epilepsy studies, increased mortality is seen in epileptic vs. control animals. Epileptic animals with high seizure frequency may exhibit deteriorating health requiring euthanasia, or may die suddenly and unexpectedly, presumably from respiratory arrest or heart failure during a seizure. Animal mortality was assessed over the time course of the long-term studies. Significantly improved survival of the epileptic animals was found after transplantation of 200K unsorted/sorted cells from lots 1 and 2 (Fig. 8Q) and 1.5M unsorted/sorted cells from lot 2, as compared to epileptic animals that received vehicle. No significant difference in survival was detected in mice treated with the lower doses of 25K and 50K cells. Example 11 [0304] This non-limiting example summarizes the results of Examples 2-10. [0305] Worldwide, about 70 million people suffer from epilepsy, and over one- third have seizures that are drug-resistant. Despite the development of next-generation small molecule antiseizure drugs, the proportion of people with pharmacoresistant epilepsy has not changed significantly in decades. Drug-resistant MTLE patients with a single, well-defined seizure focus in the temporal lobe may be eligible for a temporal lobe resection or laser ablation surgery. However, these surgeries are destructive to tissues surrounding the seizure focus and can have irreversible adverse cognitive effects. Furthermore, there are many patients with drug-resistant MTLE who are not eligible for resection/ablation surgeries. Thus, there is a medical need to develop new therapeutics for drug-resistant epilepsy, particularly using strategies that more precisely target seizure foci and are not tissue-destructive, such as GABAergic interneuron cell therapy. [0306] Pallial, MGE-derived, SST- and PV-expressing GABAergic interneuron loss of function has been implicated in human MTLE. Therefore, the pallial MGE GABAergic interneuron lineage represents an ideal physiological target for cell restoration therapy. Here highly efficient and consistent directed differentiation of hESCs into pallial MGE-type GABAergic interneurons with >85% purity without sorting was demonstrated. Pallial lineage purity was further enriched to >99% using an ERBB4-based purification step. Upon detailed investigation of long-term engraftment, preliminary safety, and disease- modifying activity following intra-hippocampal administration into a chronic mouse model of MTLE, both the sorted and unsorted cell lots were comparable in terms of efficacy and safety, suggesting that >85% pallial-type interneuron purity is sufficient, and <15% subpallial neuron content is tolerable, in the MTLE model. [0307] The intrahippocampal kainate mouse model of chronic focal epilepsy was chosen because of its high face validity to hallmark symptoms of clinical MTLE, i.e. mesiotemporal seizures and hippocampal sclerosis. Secondly, it has higher construct validity than acute seizure threshold models that are widely used for screening of novel anticonvulsant drug candidates, as the mice are chronically epileptic before administering the therapeutic candidate. Recognized as an etiologically relevant model, it is used in the NIH/NINDS-funded Epilepsy Therapy Screening Program, which aims to support progress in the development of new ASDs. Thirdly, high predictive validity can be expected since this model is less responsive to the ASDs commonly prescribed for chronic focal epilepsy, mimicking pharmacoresistant focal epilepsy patients who may be candidates for cell therapy in the future. [0308] The total number of surviving human interneurons appeared to plateau at higher dose levels, suggesting a compensatory mechanism for regulating inhibitory tone and/or a limitation of maximum engraftable cell number/volume per region of brain tissue. With respect to potential future clinical translation, it is encouraging that similar efficacy was achieved over a wide dosing range from 200K to 1.5M interneurons per epileptic hippocampus, and that no adverse behavioral effects were observed. [0309] In addition to long-term cell persistence, dose-dependent suppression of mesiotemporal seizures, and lack of adverse side-effects in the MTLE model, transplanted human pallial MGE-type interneurons significantly reduced granule cell dispersion, a typical pathology of the epileptic hippocampus. Dentate granule cell dispersion and overall neurodegeneration were lower in the epileptic animals that received interneuron transplantation. Without being bound by theory, reduced granule cell dispersion was likely the result of graft-mediated seizure suppression. [0310] It was also intriguing that epileptic animal mortality was reduced following cell administration. This mouse model of MTLE is immunodeficient, has high seizure frequency, and involves three separate stereotactic surgeries to inject kainate, transplant cells, and implant EEG electrodes. Consequently, the MTLE mice exhibit elevated premature mortality compared to non-epileptic mice of the same strain. The cause of spontaneous mortality is not always known; however, animal death immediately following a seizure was observed, similar to sudden unexpected death (SUDEP) in people with epilepsy. Interestingly, epileptic animals treated with cells had reduced mortality by 1-2 months post- transplant, before the human interneurons began to suppress seizures. Example 12 [0311] This non-limiting example shows cryopreservation of a cellular composition of pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells, and cell dose preparation post-thaw. [0312] Long-term storage of the pluripotent stem cell-derived, pallial, MGE-type inhibitory interneuron cells (as described in Example 2) was achieved by cryopreservation in a formulation containing cryoprotective agents, energy substrates and supplements that prevent intracellular icicle formation, protect cell membranes by association with the cell surface, scavenge free radicals while providing pH buffering, oncotic/osmotic support, and stable ionic concentrations at low temperatures. [0313] Prior to cryopreservation, the cells were incubated in a buffer containing high molecular weight disaccharides, amino acids, and proteins that impart physical and chemical stability to intact cellular membrane structures at about 4°C and incubation hold time of about 30 minutes. This incubation reduced the toxic effects of high freeze concentration of extracellular solutes inherent to cryopreservation of cells in DMSO- containing cryoformulation. [0314] The cells were frozen slowly in a controlled rate freezer, by cooling at a specified rate (about 1 degree per minute) past the point of ice crystal nucleation to approximately -20 to -80°C. The cells were then in liquid nitrogen . [0315] Cryopreserved cells were thawed rapidly, 0.5 – 5 mins at 30 – 40°C, and rehydrated slowly, 0.5 - 2 mins/mL, in thaw medium containing DNase (500-2000 units/ mL), supplements and sodium ions (100 – 600 mM) to scavenge free radicals while maintaining high osmolarity in order to reduce the risk of rapid cell expansion and cellular membrane damage. These careful freezing and thawing steps maximized cell viability and yields post-thaw. [0316] Post-thaw and rehydration, cells were incubated at 0.1 - 300 x 106 cells/mL for 0.5-30 hours at 0-25°C in a solution composed of lipid polymers, poloxamers, ions, nutrients, and buffered solution in order to facilitate cell membrane repair, restore intracellular electrochemical equilibrium, and maintain physiological pH balance. Inclusion of poloxamer in the vehicle also facilitated further concentration of cells by minimizing shear stress and reducing cell aggregation. The cells were further stored with high viability and recovery for up to 5 days when held in a buffered solution to allow long-term stability of the cells (FIG. 15). FIG. 15 shows that the viability of cells appears to be stable after an extended period of holding up to 120 hrs (when measured by Trypan blue membrane exclusion and NC-200). [0317] The cells were then reformulated in a final cell delivery vehicle containing a buffered solution at physiologic pH. The delivery vehicle contained supplements, lipid polymers, poloxamers, and/or MRI contrast agents, such as gadolinium, to enable visualization of cell delivery under intraoperative MRI. Example 13 [0318] This non-limiting example shows preparation and use of the cell delivery system for administering a cellular composition of pluripotent stem cell-derived, pallial, MGE-type inhibitory (e.g., GABAergic) interneuron cells to a subject. [0319] A cannula was loaded with a suspension of pluripotent stem cell-derived, pallial, MGE-type inhibitory interneuron cells (NRTX-1001), and was not subject to further changes in cell concentration due to gravity sedimentation of cells. As such, cells suspended at a sufficiently high cell concentration in a final cell delivery vehicle formulation can be stably held in the cannula at different orientations for an extended period of time (0.5-96 hours) during surgical preparation for transplantation. [0320] The delivery system was prepared as follows (FIG. 24): (1) A cannula was attached to a syringe loaded with a chase vehicle (including a vehicle with identical composition to the cell-containing vehicle). The cannula was primed with the cell-free chase vehicle delivered from the syringe. The concentrated cell suspension in a reduced volume was loaded into the cannula volume from the proximal tip (closer to the patient-facing end) of the cannula by drawing the syringe plunger, and was subsequently efficiently expelled from the outlet of the cannula by the cell-free chase vehicle, whereby the cell-free chase vehicle filled the remaining volume of the cannula and syringe, without the need to completely fill the entire cannula and syringe volume with the cell suspension. A syringe pump was used to control the volume and rate of cell delivery. Pumping cell product into and out of the straight lumen of a cannula avoided acceleration and shearing effects that may occur at the transition from large diameter syringes to small diameter outlets. [0321] The delivery system achieved consistent deposition, by cell number and volume delivered, of freshly thawed NRTX-1001 cells as well as of thawed NRTX-1001 cells that were held for 24 hours before depositing (FIG. 16A, left and center panels). The deposited cells retained high viability when freshly thawed and after a 24-hour cell hold (FIG. 16A, right panels). The clinical dose of cells and volume were delivered consistently (FIG. 16B, top panels). Further, the cells in a clinical dosing ranges were delivered with a consistent flow rate, with nominal back pressure. (FIG. 16B, bottom panels). [0322] The composition was also stable after extended hold periods in the cannula. Cryopreserved cells were thawed (see Example 12) and went through a post-thaw hold period, either as a diluted cell suspension at room temperature overnight, or as a concentrated cell suspension for 72 hours (FIG. 17, time lines). After the post-thaw hold, the cells were loaded in a cannula and held for different lengths of time at room temperature before delivery. Both the volume and cell concentration delivered from the cannula remained sufficiently stable over increasing hold times in the cannula, up to 10 hours or longer (FIG. 17, left and center-left panels). Thus, the dose of cells delivered relative to the target dose was also sufficiently stable after increasing hold times in the cannula (FIG. 17, right panels). High viability of the delivered cells was also maintained after extended hold times in the cannula (FIG. 17, center-right panels). [0323] The cells retained migratory potential after extended hold in the cannula post thaw. Cryopreserved and thawed cells that were then loaded and delivered from a cannula were tested for migratory potential. The cells maintained migratory potential after being held for up to 24 hours in the cannula (FIG. 18). Example 14 [0324] This non-limiting example shows non-invasive biomarkers of seizure activity. [0325] Detectable structural and metabolic alterations can be studied longitudinally using magnetic resonance imaging (MRI), positron emission tomography (PET) and magnetic resonance spectroscopy (MRS) to evaluate changes in the epileptic brain before and after cell therapy. Following cell administration, longitudinal MRS data can be acquired to evaluate levels of metabolites in brain regions of interest, including N- acetylaspartate (NAA) for neuronal viability, myoinositol for inflammation and gliosis, glutamate for excitatory neurotransmitter proxy of neural excitation, and γ-Aminobutyric acid (GABA) for inhibitory neurotransmitter proxy of therapeutic activity of the inhibitory interneuron cell therapy. Additionally, MRI and PET scanning can be performed before and after cell administration to evaluate volume, edema, blood flow, oxygen metabolism and glucose levels in brain regions of interest. These changes in metabolites and tissue structure that are detected by MR and PET evolve over time and can be corrected to non-epileptic control levels following cell therapy administration. Example 15 [0326] This non-limiting example shows hESC-derived, pallial, MGE-type GABAergic interneurons retain MGE pallial interneuron fate after transplantation into a host brain. [0327] Molecular characterization of human pallial interneurons 1-18 months post transplantation (MPT) using single nuclei RNA sequencing (snRNAseq). Neonate mouse cortex was transplanted with human cells (obtained as described in Example 2) and dissected at 1 MPT, 3-4 MPT, 6-7 MPT, 12 MPT and 18 MPT. Cortical tissues were processed to isolate nuclei and stained with an antibody against human nuclear antigen to enable unbiased enrichment of all the grafted human cells by fluorescence activated nuclei sorting (FANS). Sorted nuclei were captured using microfluidics controller (10X Genomics), barcoded and processed for snRNAseq. Following alignment, mapping and quality controls to remove contaminating mouse nuclei, a total of 114,655 human single nuclei were analyzed from 4 independent lots at 5 time points. [0328] UMAP (Uniform Manifold Approximation and Projection) visualization of cell clusters from all the integrated samples identified 11 clusters (#0-10), with cluster #9 representing a distinct, likely supballial MGE population, making up less than 5% of cells across all lots and timepoints (FIG. 19A). FIG. 19B shows the results from independent Unsupervised prediction algorithm, comparing hESC-derived pIN gene expression with endogenous human pINs from adult M1 cortex. Prediction scores between 0 and 1 are plotted for each cell based on the transcriptome-wide similarity in gene expression between the query (in vitro-derived cells) and the reference (in vivo subclasses). All the in vitro- derived cells (except cluster 9) have strong prediction scores for one of three MGE-type pallial IN subclasses: PV, SST, NPY. FIG. 19C shows a dot plot for key genes that define different cell categories, including general markers of neurons, GABAergic neurons, MGE, MGE subpallial neurons, and other off target regions and cell types, including preoptic area (POA), CGE, LGE, neuronal progenitors, cell cycle, pluripotent, as well as genes associated with glial cells, glutamatergic neurons (Glu), dopaminergic neurons (DA), serotonergic neurons (5HT) and cholinergic neurons (Ach). Feature plots showing gene expression across cells are shown in FIGs. 19D-19F. Darker shade correspond to higher expression level. Markers shown include genes that are expressed and maintained in MGE-type pINs postnatally and into adulthood (FIG. 19D); genes that are enriched in subsets of MGE-type pINs (FIG. 19E); genes that are enriched in subsets of CGE-type pINs (FIG. 19F). Subclass categories of transplanted human cells based on prediction and cluster marker analyses are shown in FIG. 19G. FIG. 19H shows quantification of graft composition by subclass categories across 5 time points post-transplant: 1 MPT (n=2 lots), 3-4 MPT (n=2 lots), 6-7 MPT (n=4 lots), 12 MPT (n=2 lots) and 18 MPT (n=1 lot). Projection of hESC-derived MGE pIN subclasses onto human prenatal-adult prefrontal cortex interneuron dataset shows overlap with MGE-derived PV, SST and NPY cortical interneuron (cIN) populations and not any of the CGE-derived cIN populations (FIG. 19I). [0329] These results confirm the MGE pallial interneuron fate of the cells post- transplantation. Greater than 95% of the human cells post-transplant are MGE pallial INs. The transplanted cells continue to express GAD1/2, LHX6, SOX6, NXPH1, ERBB4, SST, NPY, and highly resemble (or cluster with) endogenous MGE pallial interneuron datasets from the published literature. Example 16 [0330] This non-limiting example shows interim results of an open label Phase I/II Clinical Study of NRTX-1001 for Drug-resistant MTLE. [0331] Two adult subjects with chronic unilateral MTLE were administered a single dose of NRTX-1001 in the affected, sclerotic right hippocampus with MRI guidance. At the time of administering the cellular composition, the subjects were concurrently being treated with anti-seizure medication, including one or more benzodiazepines. The frequency of focal seizures experienced by the subject was determined based on self-reported number of seizure events. [0332] In Subject #1, a single administration of the cellular composition reduced the frequency of overall seizures by about 95% from a pre-dosing baseline of about 32 per month, over at least 13 months after administration (FIG. 20, left panel). This included a 95% reduction in focal aware seizures, and a 96% reduction in focal impaired awareness seizures. In Subject #2, a single administration of the cellular composition reduced the frequency of overall seizures by about 95% from a pre-dosing baseline of about 14 per month, over at least 8 months after administration (FIG. 20, right panel). This included a 100% reduction in focal aware seizures, and a 63% reduction in focal impaired awareness seizures. [0333] Subject #1 was further monitored using hippocampal MR spectroscopy to assess levels of various biomarker metabolites (normalized to creatine) (FIG. 21). The levels of each marker were assessed in the right (treated) hemisphere. The level of myoinositol, a marker of neuroinflammation, showed a consistent trend of reduced levels after administration (FIG. 21, left panel). The level of N-acetylaspartate (NAA), a marker of neuronal viability, was consistently higher in the treated hemisphere after administration (FIG. 21, center-left panel). Further, the level of GABA was increased in the treated hemisphere after administration of NRTX-1001 (FIG. 21, right panel). [0334] The treated subjects were further assessed for cognitive ability. The subject’s cognitive ability was tested for word retrieval (Boston Naming Test), verbal memory (Rey Auditory Verbal Learning Test (RAVLT)), and visuo-spatial memory (Brief Visuospatial Memory Test (BVMT)) at intervals after administration and compared to baseline. There was no detectable cognitive decline in either subject, and potential improvement was observed after single administration of the cellular composition (FIG. 22). [0335] Subject #1 showed improvement in neurocognitive scores in all tests by 12 months after administration (FIG. 22, left panel). Word retrieval improved by 6 months after administration. For verbal memory, delayed recall in the RAVLT improved by 6 months, and immediate recall improved by 12 months. Visual memory assessed by delayed recall and percent retained in the BVMT improved by 6 months. [0336] Subject #2 showed improvement in neurocognitive scores in verbal memory, compared to baseline by 6 months after administration (FIG. 22, right panel). Word retrieval remained within normal range over 6 months. For verbal memory, delayed recall in the RAVLT improved by 6 months, and immediate recall remained within normal scores. Visual memory assessed by percent retained in the BVMT improved by 6 months, and remained the same for delayed recall. Example 17 [0337] This non-limiting example shows effects of transplanted human pallial MGE-type interneurons in a model of Alzheimer’s disease (AD). [0338] Hyperexcitability in 5xFAD AD model is thought to sensitize the effect of urethane in theta oscillation duration but not frequency. Further, reduction of gamma activity by riluzole is more prominent in AD models. To measure theta oscillation and gamma activity, 5xFAD mice were implanted with hippocampal electrodes and treated with urethane or riluzole. [0339] As shown in FIG. 23A, urethane injected in vehicle-treated (“V”) 5xFAD mice showed a significant effect on theta duration when compared to animals transplanted with hESC-derived interneurons (“C”). No effects were observed in theta peak frequency (FIG. 23A). [0340] As shown in FIG. 23B, a significant reduction in slow gamma peak frequency was induced by riluzole in vehicle-treated 5xFAD animals (“V”) but not in animals transplanted with hESC-derived interneurons (“C”). No effects were observed in the time spent exploring new objects (FIG. 23B). Example 18 [0341] This non-limiting example provides an embodiment of a method of treating seizure activity in a subject. [0342] A population of MGE-type GABAergic neurons is differentiated from human embryonic stem cells as described in Example 2 (without sorting). The EOP neurons are sorted for NRP2. The sorted population has higher proportion of cells expressing LHX8 and not expressing ERBB4 compared to the unsorted population, and thus is enriched for the subpallial lineage. [0343] The population of MGE-type GABAergic neurons enriched for the subpallial lineage is administered to a subject suffering from focal onset seizures. After administration, the frequency of focal onset seizures is reduced compared to before administration. Example 19 [0344] This non-limiting example provides an embodiment of a method of treating seizure activity in a subject. [0345] A population of MGE-type GABAergic neurons is differentiated from human embryonic stem cells as described in Example 2 (without sorting). The cells expressing ERBB4 are sorted away from the EOP neurons. The resulting population has higher proportion of cells expressing LHX8 and not expressing ERBB4 compared to the unsorted population, and thus is enriched for the subpallial lineage. [0346] The population of MGE-type GABAergic neurons enriched for the subpallial lineage is administered to a subject suffering from focal onset seizures. After administration, the frequency of focal onset seizures is reduced compared to before administration. Example 20 [0347] This non-limiting example provides an embodiment of a method of treating seizure activity in a subject. [0348] A population of MGE-type GABAergic neurons is differentiated from human embryonic stem cells as described in Example 2 (without sorting), except MEK inhibition is omitted. The EOP neurons have a higher proportion of cells expressing LHX8 and not expressing ERBB4 compared to neurons differentiated with MEK inhibition, and thus are enriched for the subpallial lineage. [0349] The population of MGE-type GABAergic neurons enriched for the subpallial lineage is administered to a subject suffering from focal onset seizures. After administration, the frequency of focal onset seizures is reduced compared to before administration. [0350] Example 21 Stable graft composition from 1 to 18 months post-transplantation, comprised of PVALB and SST MGE interneuron subclasses [0351] To quantitatively characterize human cell fate and long-term graft composition in the brain, five different lots were transplanted into neonate cortex and cortical samples were collected at 1, 3-4, 6-7, 12 and 18 months post-transplant (MPT), followed by nuclei isolation and snRNAseq. To enrich the proportion of human cells prior to sequencing, an antibody against human nuclear antigen (HNA) was used, enabling unbiased selection of all the human cells based on HNA fluorescence-activated nuclear sorting (FANS) (FIG. 25A). In addition to physical enrichment, which typically increased the proportion of human nuclei from <1% to >50%, the reads from snRNAseq were mapped to both mouse and human transcriptomes enabling bioinformatic selection of only the human cells for downstream analyses. Collectively, 2-4 biological replicates were profiled for each of the five time points (N=14 samples), achieving a median of 9,461 cells per sample for a total of 130,557 transplanted human cells. [0352] Seurat was used to integrate all the cells across samples and time points, generating 11 high quality clusters, without notable batch effects (FIG. 25B; FIG. 26A-C). Expression of neuronal, GABAergic, pallial GE-derived and MGE markers was detected across the clusters without emergence of off-target markers over 18 months (FIG. 25C, 25D; FIG 26D). To objectively interpret transplanted cell identity in terms of major cell classes, the human adult whole brain snRNAseq reference dataset was used, which sampled over 100 anatomically distinct brain regions derived from telencephalon, diencephalon, midbrain, hindbrain, and anterior spinal cord 42. In this dataset, 30 neuronal and non-neuronal superclusters corresponding to major cell classes were defined, providing a diverse transcriptional reference, to which transplanted cells were compared. Prediction analysis indicated that 95-98% of the cells across time points matched specifically MGE INs and not any off-target cell classes (FIG. 25E-G; FIG. 26E). Moreover, classification based on brain region revealed that transplanted cells corresponded strongly to the cortex, and to a lesser degree to the hippocampus and amygdala, all of which contain MGE-derived INs (FIG. 26F). [0353] A small proportion of cells (<3%), confined primarily to cluster 10, exhibited low MGE IN prediction scores (FIG. 25F). Cluster 10 was distinguished by co- expression of ADARB2 along with MGE IN markers (SOX6, LHX6, SST, RELN) and several other genes that appeared in the LHX6/ENC1/LHX8 pre-transplant cluster (FIG. 25C, 25D, 25I, 25N). Interestingly, while ADARB2 is a common marker of CGE-derived INs, no other CGE-associated markers (SP8, SCGN, VIP, HTR3A, CCK, CALB2, LAMP5) were expressed (FIG. 25D, 25I). Considering that ERBB4 is also expressed in this population (FIG. 25D, 25I), and the cells persist long-term in the cortex, it was hypothesized that cluster 10 might represent an unusual, perhaps human-specific MGE IN cell type that is not well annotated in the reference datasets. This idea is supported by identification of some unconventional interneuron populations, including double-positive ADARB2/LHX6 cells that are expanded in the human neocortex compared to the rodent, and for which classification based on developmental origin (MGE-derived) does not match with the classification based on the adult transcriptional profile (CGE-like) 43-47. Thus, cluster 10, henceforth designated as “ADARB2” represents a minor transcriptionally distinct GABAergic population within human grafts. [0354] To determine subclass identity of the transplanted hMGE-pINs, multiple human adult reference datasets were used with the most recent annotations of interneuron subclasses and subtypes from different cortical regions, including the middle temporal gyrus (MTG), primary motor cortex (M1) and prefrontal cortex (PFC) 48-51. Prediction analyses demonstrated that all the in vitro-derived clusters except ADARB2, belonged to one of three main MGE subclasses: PVALB, SST or SST NPY (commonly referred to as SST CHODL) (FIG. 25H). Surprisingly, subclass prediction was robust by 1 MPT, long before functional and neurochemical interneuron maturation occurred, though scores increased with time post- transplant, especially for the PVALB and NPY populations (FIG. 26G). [0355] Expression patterns of known subclass markers reinforced prediction model results. For instance, known PVALB lineage markers, including ERBB4, SLIT2, SHISA9, RUNX2 (FIG. 25I; FIG. 26H) and several genes encoding potassium channel subunits associated with fast-spiking properties (KCNJ3, KCNAB1, KCNC2) (FIG. 25N) 49 were enriched in the predicted PVALB population, although PVALB itself was not expressed. Likewise, SST lineage-associated markers, including SST, RELN, BCL11A, NPAS1, NPAS3, SYNPR, GRIN3A and GRIA3 were enriched in the predicted SST population (FIG. 25I, 25N). Finally, the predicted SST NPY population was characterized by co-expression of SST with NPY, NOS1, TACR1, TOX and others (FIG. 25I, 25N). Interestingly, none of the transplanted cells had strong prediction scores for MGE-derived fast-spiking Chandelier or Lamp5/Lhx6 neurogliaform cells, or any of the CGE-derived subclasses, consistent with lack of corresponding markers (FIG. 25H, 25I). [0356] Based on highly concordant results from the prediction model and data- driven clustering / gene expression analyses, graft composition could be quantified for all the lots and time points. It was determined that human hMGE-pIN grafts consisted of ~20-40% PVALB, 60-80% SST, 5-10% NPY and <5% ADARB2 subclasses (FIG. 25J-25L). The range was attributed to the variation among biological replicates corresponding to independent manufacturing lots (FIG. 25L). Average composition was stable from 3-4 MPT and beyond (FIGs. 25K-25L), but from 1 to 3-4 MPT a small decrease in PVALB cells for a given batch was observed (FIG. 25M). To assess the accuracy and consistency of composition quantification, repeatability experiments were performed, transplanting the same lot from 5 different frozen vials and tracking each vial independently through sorting and sequencing at 1 MPT and 4 MPT. The composition across repeated measurements was nearly identical (FIG. 25M), highlighting the remarkable consistency of this multi-step analysis pipeline and indicating that even a single measurement provides a reliable representation of graft composition for a given lot. Importantly, no new or off-target cell types arose from the grafts even after 1.5 years. [0357] To validate the profiling results, several fluorescence in situ hybridization (FISH) probes were used designed to distinguish the main cell populations. To identify human cells, a probe against MALAT1 was used, because it was the most highly and ubiquitously expressed transcript across all the cells and time points in the snRNAseq dataset (99.99% of the cells are positive) (FIG. 26I). GABAergic marker glutamate decarboxylase 1 (GAD1) was used as a positive control, as it should be expressed by all the subclasses (FIG. 26J), and this was corroborated with FISH (FIG. 26K, 26L). SLIT2 expression is stronger in PVALB than in other interneuron populations in vivo (FIG. 26H) and in the transplanted cells (FIG. 26J), although there are cells that co-express SLIT2 and SST (FIG. 25I). Therefore, to identify putative PVALB cells, both probes were combined in the same staining cocktail and quantified SLIT2+/SST- cells (FIG. 26K, 26L). The percent of SLIT2+/SST- cells at 1 MPT and later time points was in good agreement with snRNAseq clustering-based quantifications (FIG. 25L). [0358] It is well known that PVALB transcript takes a really long time to reach robust expression levels (after age 10 in humans) 50, 52, but it was found that to a lesser degree this is also true for human SST. SST transcript levels increased steadily with time in both the SST and SST NPY subclasses, and it took 12 MPT to reach robust expression levels in the SST subclass (FIG. 26J, 26L). This incredibly prolonged neurochemical maturation of human interneurons explains why immunostaining approaches against PVALB and SST antigens greatly underestimate both populations, especially at earlier time points 1, and why the transcriptomic approach relying on thousands of genes is much more sensitive. In contrast, the NPY transcript was already expressed robustly at 1 MPT, enabling early detection of this population with the FISH probe (FIG. 26J-26L). Overall, the FISH experiments yielded similar estimates of the three main MGE populations in the grafts to the analyses based on snRNAseq clustering (FIG. 26K; FIG. 25L), but underscored the limitations of the probes- based approach relying on 1-2 markers for quantitative assessment of cell types. Example 22 Transplantation environment triggers expression of synaptic genes enabling rapid cell fate identification [0359] The rapid post-transplant specification and robustness of the prediction model was leveraged to ask whether cell fate could be discerned in vitro without transplantation, perhaps after extended culture, and whether it is possible to discern cell fate even sooner than 1 MPT—thus addressing the effects of timing and environment. Nuclei were sequenced from one lot (010519S1) immediately post-thaw, after a month of in vitro co-culture with astrocytes (30 DIV) and 14 days post-transplantation (14 DPT). These new samples were integrated with pre-transplant whole cell and 1 MPT data from the same lot to identify similar cell types (FIG. 27A; FIG. 28A). Clustering all the samples together enabled guided subclass assignments for the in vitro cells (FIG. 27B; FIG. 28B) and revealed the transcriptomic relationship between pre-transplants and post-transplant populations (FIG. 27C). Alluvial plots suggested that the main pre-transplant LHX6/MAF/ZEB2 population gives rise to all the subclasses present in vivo, whereas the LHX6/ENC1/LHX8 population only contributes to ADARB2 (FIG. 27C). In addition, while a small proportion of SST and SST NPY subclass cells are related to the pre-transplant LHX6/SST/NPY population, PVALB cells are almost exclusively derived from the LHX6/MAF/ZEB2 pre-transplant population. [0360] Despite this apparent transcriptomic relationship between the pre- and post-transplant populations, prediction scores based on the adult MTG interneuron reference were very low for all the in vitro samples, even after 30 DIV (FIG. 27E, 27F). In contrast, 14 DPT was similar to 1 MPT in terms of clustering, composition and prediction results (FIG. 27D-27F), albeit with lower prediction scores (FIG. 27F). Moreover, subclass-enriched markers such as ERBB4 (PVALB-enriched) and RELN (SST-enriched) did not exhibit characteristic expression gradients after 30 DIV that are already observed in vivo at 1 MPT (FIG. 28C). These results suggest that transplantation into the brain promotes transcriptional changes associated with cell identity after just a few weeks, when human interneurons are still quite immature. Indeed, DGE analysis between 30 DIV and 1 MPT samples demonstrated that endogenous environment is characterized by enrichment in synaptic transmission genes (FIG. 28D) and subclass-specific gene expression patterns (FIG. 27G), thus enabling rapid cell fate identification and accurate prediction. Example 23 Cell development is characterized by major transcriptional changes during the first 3 MPT followed by gradual unfolding of gene modules involved in regulation of synaptic transmission and membrane potential [0361] To characterize the transcriptional maturation of ESC-derived hMGE- pINs in the context of human interneuron development, an integrated dataset of 169 human cortical samples from over 100 donors was leveraged, spanning from the second trimester of gestation to adulthood 51, which also incorporated other datasets 50, 53, 54, narrowing the reference to the cortical interneurons therein. To avoid overinterpretation, given that hMGE- pINs were transplanted into the mouse cortex and therefore lacked many environmental ques that normally shape human interneuron maturation, the analysis was limited to very broad stages (2nd trimester, 3rd trimester, and after birth), corresponding to major physiological changes in circuit development (FIG. 27H, based on 19). When projected onto human cIN developmental trajectory, pre-transplant samples (PRE) aligned with the initial class of endogenous postmitotic interneurons, with intermixing between the future subclasses (FIG. 27J). Most PRE cells matched the 2nd trimester stage (FIGs. 27H-27J), consistent with previous analysis using only the developing human GE reference. By 1 MPT cells moved down the developmental MGE, but not CGE trajectory, with visible separation between subclasses (FIG. 27J), although most cells still matched 2nd trimester (FIGs. 27H, 27I). By 3- 4 MPT more than half of the PVALB and SST cells corresponded to 3rd trimester or later. The proportion of neurons progressively moving down their respective branches increased with subsequent timepoints, reaching early postnatal-like stages by 18 MPT (FIGs. 27H-27J), indicating continued in vivo maturation. [0362] Integration of all the samples across time points indicated that cell fate accounts for more transcriptional variation in the post-transplant data than cell age (FIG. 25). To investigate the more subtle molecular programs underlying cell maturation, all the samples were pooled together and clustering was performed without integration. This revealed three major transcriptional states illustrated by shifts in the UMAP space (FIGs. 29A-29C): pre-transplant (PRE), 1 MPT, and 3-18 MPT. Across these major transitions, neuronal migration gene DCX and key transcription factors that are critical for MGE-pIN specification (such as DLX1/2/5, MAFB, MAF, ARX, ZEB2) are notably downregulated after transplantation, whereas general neuronal (MAP2), GABAergic (GAD1, GAD2) and MGE (LHX6, SOX6) markers remained relatively stable (FIG. 29). DGE analysis demonstrated that the PRE stage was enriched with genes involved in forebrain development, neuronal differentiation, cytoskeletal regulation/migration, and regulation of neuron projection/axon development (FIG. 29E, 29F; FIGs. 28E-28G). At 1 MPT, projection/axon guidance and neuronal migration programs were still engaged, but now they were complemented by programs involved in cognition, learning and memory, synapse organization and glutamatergic transmission (FIG. 29F; FIGs. 28E-28G). Beyond 3 MPT, there was an upregulation of plasma membrane cell adhesion molecules and significant enrichment in genes involved in modulation of chemical synaptic transmission and regulation of ion transport and membrane potential (FIG. 29F; FIGs. 28E-28G). GO-term enrichment analysis for cellular components and molecular function clearly demonstrated the rapid transitions from active cytoskeletal programs pre-transplant to receptor and signaling activity at the plasma membrane at 1 MPT, followed by more specific channel activity at 3+ MPT (FIG. 28E-28G), providing transcriptional evidence for the kinetics of graft integration with the host circuitry. Of relevance, in the rodent model of focal temporal lobe epilepsy (TLE), the grafted hMGE-pIN cells had no effect on seizures at 1-2 MPT, but by 4 and 5 MPT there was significant seizure reduction 1, which may be explained by the kinetics described above. [0363] While the transcriptional shifts during the first 3-4 MPT were clear, subsequent changes were more subtle, with samples from 3 to 18 MPT largely overlapping in the UMAP space (FIG. 29A-29C). This suggests that cell maturation beyond the first few months may be primarily mediated by changes at the post-transcriptional level, perhaps explaining why the prediction model shows strong similarly between adult reference cell types and corresponding cell grafts, despite the vast differences in age and species environments. Nonetheless, focused DGE analysis comparing the time points between 3 and 18 MPT uncovered gradual upregulation of genes involved in G protein-coupled receptor signaling, synaptic vesicle organization and transport, ion transport, glutamatergic synaptic transmission and regulation of membrane action potential (FIG. 29G-29L). Temporal expression of the largest non-overlapping gene modules in grafted and endogenous cINs was examined: “modulation of chemical synaptic transmission”, upregulated significantly after 3- 4 MPT (FIG. 29H, 29I) and “regulation of membrane potential”, upregulated significantly after 6-7 MPT (FIG. 29H, 29J). Both modules increased post-transplant (FIG. 29I, 29J top rows) and with endogenous development, the latter peaking during early neonatal ages and aligning with the latest grafted sample (18 MPT) from the study (FIG. 29I, 29J bottom rows). A subset of genes contributing to these modules were broadly expressed, but many showed subclass-specific enrichment (FIG. 29K, 29L). In particular, several developmentally regulated voltage-gated potassium channels that enable sustained fast spiking properties of PVALB INs (ex.: Kv3 encoded by KCNC1 and KCNC2) were upregulated in the hESC- derived PVALB subclass, especially after 12 MPT (FIG. 29L). Example 24 hMGE-pIN grafts are comprised of multiple PVALB and SST subtypes, including Basket cells, non-Martinotti, Martinotti and Long-projecting SST cells [0364] Pallial interneurons exhibit remarkable diversity, with 72 transcriptionally defined subtypes conserved across adult cortical areas 48. To assess how many subtypes are represented within hMGE-pIN grafts, cluster correlations to each other were analyzed. Within the predicted PVALB subclass, cluster 9 is very distinct, whereas clusters 5 and 1 are highly correlated to each other (FIG. 30A), suggesting at least two PVALB populations. Cluster 7 is correlated with both PVALB and SST subclasses, consistent with overlapping marker expression gradients (FIG. 25I). Within the predicted SST subclass, there appears to be a continuum including clusters 0, 4, 3, 2, and 8, with multiple related populations. Finally, clusters 6 (SST NPY) and 10 (ADARB2) are transcriptionally distinct (FIG. 30A) and likely represent independent cell types. While these analyses suggested multiple PVALB and SST populations, understanding their exact number and identity required additional analyses. [0365] Towards that end, the overlap between the 18 MPT hMGE-pIN and human cortical IN snRNAseq clusters was investigated, reasoning that the oldest cells in the study should be the closest to the adult reference. The proportion of cells in each 18 MPT hMGE-pIN cluster overlapping with each of the 72 transcriptionally defined MGE- and CGE-derived IN clusters was computed, and >10% overlap was plotted with a heatmap (FIG. 30B). In vitro-derived subtype identity was then inferred based on matching endogenous human/mouse consensus cluster identities defined through multimodal analyses 10. This approach revealed that cluster 9 (PV1) strongly overlaps with human “L2-5 PVALB RPH3AL” cluster, which corresponds to the upper layer fast-spiking Basket cells, whereas clusters 5 and part of 1 (PV2) overlap with human “L5-6 PVALB GAPDHP60” cluster, which corresponds to the deep layer fast-spiking Basket cells (FIGs. 30B, 30C). None of the hESC-derived clusters overlapped with human Chandelier cells (FIGs. 25E, 25H), indicating this PVALB subtype is not generated with the protocol. Molecular analyses thus suggest that PVALB interneurons in the grafts likely correspond to Basket cells. Cluster 7 (PV/SST) partially overlapped with three human clusters, including two deep layer non-Martinotti SST clusters and L6 Th+ SST/PV population, confirming that this cell population likely shares the properties of both subclasses. Of note, this cluster was not counted towards PVALB (FIGs. 25J-25M), even though some of the cells could be fast-spiking. [0366] Clusters 0 and 4 (SST1) overlapped with a few human SST clusters corresponding to deep layer non-Martinotti cells (FIGs. 30B, 30C). Clusters 3, 2 (SST2) and 8 (SST3), on the other hand, overlapped with deep and superficial layer T-shaped Martinotti human clusters, respectively (FIGs. 30B, 30C). The last SST population, cluster 6 (SST NPY), overlapped strongly (88%) with the human Long-range projecting “L1-6 SST NPY” cluster (or LRP), which is highly conserved between human and mouse (100% overlap) (FIG. 30B). Quite interestingly, cluster 10 cells (ADARB2) overlapped extensively (>95%) with the human “L3-6 PAX6 LINC01497” cluster (FIG. 30B). However, the overlap between this human and the closest matching mouse cluster “Lamp5 Pax6” is only 20%, and neither human nor mouse cells appear to be classified in terms of physiology or morphology 10. Thus, as mentioned earlier, this minor population in the grafts could represent a human- specific MGE pIN subtype that is not well-characterized. This is further supported by the finding that most ADARB2 cells appear to have emerged from the main LHX6/MAF/ZEB2 initial class of pre-transplant interneurons (FIG. 30C). Importantly, hMGE-pINs do not exhibit transcriptional overlap with any of the well-defined CGE-derived IN subtypes, highlighting specificity of the derivation method 1. Overall, these analyses demonstrate that hMGE-pINs grafts consist of diverse transcriptionally defined subtypes, including upper (PV1) and lower (PV2) FS Basket cells (~21% total), SST/PVALB cells (~7%), non- Martinotti (SST1, ~32%), Martinotti (SST2 and SST3, ~33% total) and LRP (NPY, ~6%) SST cells, as well as ADARB2 cells (~1%) (FIGs. 30C, 30D). Of these, only the upper layer FS Basket cells (PV1), do not persist well after 1 MPT, dropping to ~1% in all the subsequent time points (FIG. 30D). Top subtype markers illustrate some of the molecular distinctions between these IN subtypes (FIG. 30E). [0367] Transcription factors (TFs) in the cell nucleus as well as multiple families of cell adhesion molecules (CAMs) and voltage-gated ion channels at the cell membrane are among the functional gene categories that regulate synaptic communication and exhibit distinct expression patterns that can discriminate among defined interneuron populations 43. Expression patterns of these gene categories across the eight subtypes defined above were assessed. Among the TFs, NFIB, ETS1, PPARGC1A (encoding PGC1A protein), and BCL6 were enriched in PVALB subtypes, with NFIB and BCL6 potentially distinguishing between superficial and deep layer Basket cells, respectively (FIG. 30F). SST interneuron subtypes were enriched for NPAS1, NPAS3 (non Martinotti), and ETV1, BCL11A (Martinotti), whereas the SST NPY Long-range projecting population was marked by TOX enrichment (FIG. 30F; FIG. 25N). These expression patterns are consistent with expression patterns observed endogenously in mouse and human cINs 43, 49, providing further evidence for the diversity of subtypes in the grafts. Finally, the ADARB2 subtype was marked by specific enrichment for LDB2 TFs (FIG. 30F). [0368] While voltage-gated ion channels in general are broadly expressed across cINs, three families including potassium (Kv), sodium (NaV) and calcium (CaV) voltage- gated ion channels and associated regulatory subunits are highly discriminative of specific subtypes 43. Consistently, many examples of subtype-specific enrichment that agree with the literature were found. For instance, among the NaV genes, SCN1A, SCN4B, SCN9A, SCN8A, SCN1B and SCN2B all show developmental upregulation and enrichment in PVALB Basket cells compared to SST and CGE-type INs 43,55, which was recapitulated in the data (FIGs. 30F, 30G). Similarly, Kv channels and regulatory subunits exhibited subtype-specific enrichments, with notable examples associated with fast-spiking interneurons such as KCNC1 and KCNC2 (encoding Kv3) and KCNA2, KCNA7, KCNAB1, KCNAB2, and KCNAB3 (encoding Kv1-type potassium channel and modulatory subunits) (FIGs. 30F, 30G). On the other hand, Martinotti cells, most clearly exemplified by SST3, showed distinct enrichment in several CaV genes, including CACNG7, CACNA1G, CACNG8, and CACNA1C (FIGs. 30B, 30F). Finally, expression patterns for the Netrin-Unc5-Slit-Robo family of CAMs were examined, notable for its specific role in cell recognition 43. Subtype-specific enrichment patterns in this gene category (FIG. 30B) suggested that this aspect of intercellular connectivity regulation is also recapitulated in the context of chimeric hMGE- pIN transplantation. Example 25 Grafted human interneurons acquire morphological and connectivity features of multiple PVALB and SST subtypes [0369] Transcriptomic analyses indicated a diversity of MGE-derived subtypes that can be distinguished by their morphologies, connectivity patterns, and molecular markers. To assess these features in vivo, cells were transplanted into the neonatal (P1-P2) mouse cortex at a single dose per hemisphere (FIG. 31A) and analyzed their engraftment at different postnatal times using immunohistochemistry (IHC). Human interneurons extensively migrated rostro-caudally (>2.4mm) and persisted up to 18 MPT (FIGs. 31B- 31D), while maintaining high levels of LHX6 expression. From 1 to 7 MPT, the transition from migratory state into maturing neurons was observed, as shown by a decrease in immature neuronal marker doublecortin (DCX) and an increase in human-specific synaptophysin (SYP), which marks the sites of presynaptic formation (FIGs. 32A, 32B). To distinguish the main PVALB, SST, and SST-NPY subclasses, IHC for ERBB4/SST and NOS1/SST markers was performed. At 7 MPT, hMGE-pINs, identified by HNA, comprised approximately 20% ERBB4+ and 40% SST+ cells, with ~10% SST+ cells expressing NOS1. Differential layer distribution was observed, depending on marker expression patterns: SST- ERBB4+ human cells (consistent with PVALB subclass) preferentially populated layers IV and VI, SST+NOS1- human cells (consistent with SST subclass) preferentially populated layers II-IV, whereas SST+NOS1+ human cells (consistent with SST-NPY subclass) preferentially populated layer VI (FIG. 31E), suggesting a considerable degree of specificity in laminar distribution in the neocortex depending on cell fate, which is consistent with endogenous distribution patterns observed in mouse and human 6, 9. [0370] To further characterize the morphologies of hMGE-pINs, cells were transduced prior to transplantation with a lentivirus encoding membrane-bound GFP. Using expansion microscopy (ExM, refs), which enabled an increase in imaging resolution by 4-5- fold, three types of morphologies were distinguished in SST-expressing hMGE-pINs, resembling Martinotti, non-Martinnotti, and LRP cells (FIGs. 31F-31P), as well as Basket- like morphologies in SST-negative cells (FIGs. 31Q-31S). Martinotti-like human cells were characterized by their long ascending axonal collaterals that profusely ramified in layer I (FIG. 31F). Similar to what has been described before, these cells displayed a pyramidal or oval shaped somas with bipolar or bitufted dendritic morphologies. The majority of these cells expressed low levels of SST together with CNTNAP4, CALB1, and ETV1 (FIG. 31F- 31H). Cells with non-Martinotti morphologies were found in layers II to V and were characterized by their multipolar morphologies and co-expression of SST with GULP1 and NPAS3 (SST1 cluster markers) (FIGs. 31I, 31J). Cells with LRP morphologies were easily identified in layer VI and were further found dispersed in layers I to V (FIG. 31K). LRP axons usually traveled horizontally, parallel to the corpus callosum, and these cells were commonly identified by their expression of NPY and SST/NOS1 (FIGs. 31L, 31M). Furthermore, NPY+SST+ axon projections were observed along the hippocampus, near the nucleus accumbens in the striatum, and traveling contralaterally through the corpus callosum in the forebrain midline (FIGs. 31N-31P). On the other hand, ERBB4-expressing cells were negative for SST and displayed a multipolar dendritic morphology (FIG. 31Q) with extensive human SYP-expressing axonal arborizations covering nearby cells, reminiscent of Basket cells (FIG. 31R). Although PVALB expression was found in a very small number of cells at late timepoints (> 17 MPT), the co-expression of ERBB4 and BCL6 was observed as early as 4 MPT (FIG. 31S), consistent with enrichment of these markers in the PVALB subclass by snRNAseq (FIG. 25I; FIG. 30F). ERBB4-expressing cells with Chandelier-like morphologies were not obserbed, consistent with snRNAseq results. [0371] Next, synapse formation and patterns of connectivity associated with different markers across the cortical layers were analyzed. SST-expressing interneurons primarily target distal dendrites, while Fast-spiking Basket cells form perisomatic and proximal dendrite synapses on pyramidal cells and other interneurons (FIG. 32C)56-58. Analyzing the expression of human-specific TAU and/or SYP, it was observed that transplanted hMGE-pINs showed abundant synapse formation in layers I/II and VI/V at 7MPT (FIGs. 32D, 32E). It was hypothesized that layers I/II synapses may be derived from human SST+ Martinotti cells, while layers IV/V may be a place for perisomatic synapse formation by PVALB subclasses. In layers I/II, inhibitory synapses were identified (as shown by the close contact between human presynaptic SYP and postsynaptic Gephyrin), which were formed by SST+ hMGE-pINs that targeted the distal dendrites of pyramidal cells (labeled by Pex5L, FIG. 32F). These axonal boutons expressed SST as well as SYNPR, and GRIN3A (FIGs. 32G, 32H), which have been suggested to play a role in SST+ cell synapse formation and specification 59. Furthermore, axonal expression of the SST2 cluster marker ARHGAP6 (FIG. 32I), a member of Rho GTPase activating protein family suggested to have an important role in human synaptogenesis was found 60. Next, synaptic formation by Basket cells in layer IV was analyzed. Human axons surrounding the soma of endogenous neurons, with several forming synapses were observed, as shown by human SYP and the host postsynaptic marker GabaR1 (FIGs. 32J, 32K). In addition, the soma-associated synapses expressed LGI2, a key protein involved in the formation of PVALB+ Basket cell synapses 59, as well as the potassium channels KIR3.1 (encoded by KCNJ3) and KV2.2 (encoded by KCNC2), which are enriched in PVALB IN subpopulations (FIG. 30; FIGs. 32L-32N). [0372] Together, these results indicate that transplanted ESC-derived hMGE-pINs display key characteristics of endogenous MGE-derived pINs, including morphologies and synaptic connectivity patterns, in addition to their maturing molecular profiles properties, suggesting subtype-specific integration into existing cortical circuitries. Example 26 Human pallial interneuron viability, persistence, distribution, and fate are stable post- transplantation following extended hold periods in vitro post-thaw [0373] Next assessed the stability of the hPSC-derived interneurons post-thaw and following a hold period in a cell delivery cannula was assessed. The data demonstrated that the viability (FIG. 33A), concentration (FIG. 33B), metabolic activity (FIG. 33C), and migratory potential (FIG. 33D) of cells held for 48 hours at 2-18°C are comparable to acutely thawed or overnight hold reference control conditions, both before and after 7 hours of cannula retention at room temperature (FIG. 33). [0374] Furthermore, in vivo persistence, migration, and distribution of the thawed and held hPSC-derived GABAergic interneurons at 1 month-post-transplantation (1 MPT) into neonate P1-2 rodent brains was unaffected by the extended hold post-thaw. These results demonstrate that cell persistence (FIG. 34A), migration (FIG. 34B) and distribution of cells (FIG. 34C) following hypothermic storage at 2-18°C for 48-72 hrs are comparable to reference control dose preparation methods (FIG. 34). Single-cell RNA sequencing analysis of hPSC-derived GABAergic neurons at 1 month and 4 months post-transplantation into rodent brains revealed no off-target cell types, off-target gene expression, or significant differences in gene expression patterns: (FIG. 34A) The gene expression profiles and composition were consistent between cells stored at 2-18°C for 48-72 hours and the control, and (FIG. 34B) were comparable between the 1-month and 4-month post-transplantation time points (FIGs. 35A-35B). Example 27 Spontaneous calcium transient activity from human pallial interneurons (hpIN) in vitro [0375] Human pallial interneurons (hpIN) co-cultured with mouse astrocytes displayed robust spontaneous action potential activity detected using calcium imaging, within 17 days of in vitro culture post-thaw. Addition of different neurotransmitter receptor antagonists demonstrated that the calcium activity was mediated by mechanisms independent of GABAA or GABAB receptors using Picrotoxin and Saclofen, respectively, and was also independent from glutamate receptors AMPA and NMDA using NBQX and AP-5, respectively. Addition of TTX (Na+ channel blocker) blocked most of the calcium activity, and strongly suggested that the calcium activity was mediated by the firing of action potentials (FIGs. 36A-36B). Example 28 Multi-electrode array analysis of co-cultured hiPSC derived glutamatergic neurons and mouse primary astrocytes with or without human GABAergic pallial interneurons (hpIN) [0376] In order to evaluate how human pallial interneurons (hpIN) can integrate in a neuronal network and influence network activity, hpIN were co-cultured in vitro with mouse astrocytes and commercially available hPSC derived glutamatergic neurons from two different sources: Cell Dynamics Incorporated (CDI Gluta) or BitBio (ioGluta). These co- cultures were performed in 24 well plates, each well containing 16 independent electrodes, in order to detect electrical activity over time using the Multi Electrode Array (MEA) system (Axion Biosystem). Assaying specific markers for either astrocytes, glutamatergic neurons or inhibitory interneurons (hpIN), immunostaining analysis demonstrated that the three different cell types persisted in this co-culture system for over 40 days in vitro (DIV). The two independent sources of Glutamatergic neurons (CDI Gluta or ioGluta), co-cultured with astrocytes, developed synchronized neuronal network activity over time, based on synchrony index and firing rate, suggesting synaptic transmission between glutamatergic neurons. The addition of hpIN in the co-culture resulted in a net decrease of the network activity and synchrony, demonstrating the functional inhibitory effect of hpIN on Glutamatergic neurons (FIGs. 37A-37T). The addition of picrotoxin, a GABA-A receptor antagonist, demonstrated that this observed reduced activity upon addition of hpIN was indeed mediated by the binding of the neurotransmitter GABA on glutamatergic neurons (FIGs. 37A-37T). These findings demonstrate: 1) hiPNs are able to integrate into excitatory neuronal networks within 14 to 21 days in vitro (DIV) post-thaw, and 2) hiPNs inhibit network activity through a GABA mediated mechanism engaging GABAA and/or GABAB receptors as expected. Example 29 Evaluation of disease modifying activity of human pallial interneurons post- administration into a rodent model of mesial temporal lobe epilepsy [0377] To assess anxiety, a modified open field protocol using an arena of 40 cm x 60cm was run at 6 months post-transplant (FIGs. 38A-38B). Epileptic mice injected with vehicle spent significantly less time in the center compared to both the naïve mice and epileptic mice treated with NRTX-1001 human pallial interneurons. Moreover, no significant difference in time spent in the center was observed between NRTX-1001 treated epileptic mice and naïve mice. Another behavior test assessing anxiety, the Light-Dark Emergence test (FIGs. 38A-38B) was also performed. A significant number of epileptic animals that were vehicle injected did not emerge into the light while all naïve mice emerged. For the animals that emerged into the light, the latency to first emergence was significantly longer for vehicle-injected epileptic mice as compared to naïve mice. However, NRTX-1001-treated epileptic mice had a similar emergence latency as the naïve mice. These results, along with results of the Open Field test described above, further suggest that NRTX-1001 human pallial interneuron treatment of epileptic mice results in reduced anxiety as compared to vehicle- injected epileptic mice. [0378] Additionally, by 8.5 months post-transplant (MPT), epileptic mice exhibit hippocampal dentate granule cell dispersion, a common feature of mesiotemporal sclerosis in human MTLE, that is significantly greater than in age-matched naïve mice. However, NRTX-1001 human pallial interneuron treated epileptic mice have significantly reduced granule cell dispersion compared to epileptic mice injected with vehicle (FIGs. 39A-39D). To find out whether NRTX-1001 treatment reduced further progression of granule cell dispersion or reversed it, six epileptic mice were perfused at the 1 MPSE (month post status epilepticus), which is the timepoint just before the epileptic mice are transplanted with NRTX-1001. Granule cell dispersion at 1 MPSE is already significantly higher than in naïve mice. However, granule cell dispersion in epileptic mice at 8.5 months post-transplant with NRTX-1001 is not significantly different from GC dispersion at 1 MPSE at the time of transplant (FIG. 39A-39D). In contrast, in epileptic mice that received only vehicle (FIGs. 39A-39D), granule cell dispersion is significantly higher at 8.5 months post-transplant than at the time of transplant. These results suggest that transplanting NRTX-1001 human pallial interneurons into the epileptic hippocampus stops further progression of granule cell dispersion. Example 30 Preliminary data from an ongoing open label Phase 1/2 clinical trial of NRTX-1001 interneuron cell therapy for drug-resistant MTLE [0379] This Example relates to Example 16. Preliminary safety data obtained from the ongoing open-label single-arm trial have shown that NRTX-1001 is well tolerated (N = 10; n = 5 at the starting dose level in Cohort 1; and n = 5 at the high dose level in Cohort 2). [0380] To date, two SAEs were reported. Both of the SAEs occurred at the same time in one subject enrolled in the low dose Cohort 1 and were attributed to a seizure cluster (categorized as status epilepticus) and related kidney injury, that required hospitalization. The subject has since been discharged and is stable. This subject had a history of status epilepticus and kidney injury before enrolling in the study. Therefore, the SAEs have been categorized as related to the underlying disease and not to NRTX-1001, the surgical procedure, or the immunosuppression regimen. The SAEs were thoroughly reviewed with the data safety monitoring board (DSMB), and their guidance was to continue the study without any modifications. All other adverse events (AEs) observed to date have been non-serious and mild to moderate in severity. None have led to study discontinuation, and none have been attributed to NRTX-1001. All AEs related to the surgical procedure itself have been resolved in both dose cohorts. The ongoing non-serious, mild to moderate AEs are attributed to the concurrent immunosuppression regimen administered during the first year of the protocol. The first 2 subjects have since discontinued immunosuppression per the protocol and have reported the resolution of all AEs at the 18-month follow-up visit. No clinically significant neurocognitive deficits have been reported to date for any of the subjects treated with NRTX-1001. In addition, none of the subjects experienced concerning changes in visual perimetry testing, brain imaging, or immune function assays. The DSMB has met three times and had no significant safety concerns. In conclusion, preliminary safety data from ten subjects at both dose levels show that NRTX-1001 is well tolerated in this patient population. [0381] The impact of NRTX-1001 on cognition and quality of life is being tested by having the patients complete the following brief battery of neuropsychological tests prior to administration of NRTX-1001, and at 6-months, 9-months, 12-months, 18-months, and 24- months following the surgical administration of NRTX-1001: [0382] Word naming via Boston Naming Test (BNT), which is a test that is sensitive to detecting compromised lexical retrieval abilities and aphasia through visual confrontation naming. [0383] Verbal episodic memory via the Ray Auditory Verbal Learning Test (RAVLT), which is a measure of a person's ability to encode, store, and recover verbal information in different stages of immediate memory. [0384] Visuospatial episodic memory via the Brief Visuospatial Memory Test - Revised (BVMT-R), which is a neuropsychological evaluation that measures immediate visual learning, delayed visual memory and recognition. [0385] Quality of Life in Epilepsy Inventory (QOLIE-31-P): contains seven multi-item scales that assess emotional well-being, social functioning, cognitive functioning, seizure worry, medication effects, and overall quality of life (note that the QOLIE-31-P test is administered at baseline, 6-, 12-, 18-and 24-month visits). [0386] The cognition and quality of life outcomes for each subject in Cohort 1, who completed at least 6 months of evaluation, are provided as percent changes from baseline observed over time after NRTX-1001 administration. [0387] 5 of 5 subjects showed no clinically significant decline persisting from baseline in cognitive performance, with some showing significant numerical improvement on neurocognitive and quality of life assessments after NRTX-1001 administration (FIG. 40A- 40D): [0388] The first two subjects (102-001 and 101-001) have data through 18- months after NRTX-1001 administration. Subject 102-001 showed significant numerical improvements across all neurocognitive parameters tested and also exhibited improvements on the QOLIE-31-P at the 12- and 18-month visits after NRTX-1001 administration. Subject 101-001 showed a transient decline in the total BNT score that was not clinically significant and later resolved. Subject 101-001 also demonstrated no significant change from baseline on other neurocognitive tests and a significant increase in QOLIE-31-P at 12- and 18-month visits. [0389] The third subject (115-001) has 12-months of data. Subject 115-001 showed a decreased BVMT delayed recall score at 12-months that was not clinically significant and did not decline on other tests. This subject showed a numerical increase in QOLIE-31-P at the 12-month visit. [0390] The fourth subject (107-001) showed a decreased BVMT delayed recall at 9-months and decreased BNT score at the 6-month visit that were not clinically significant but had a numerically increased QOLIE-31-P score at the 6-month visit. [0391] The fifth subject (104-001) showed no significant decline on any parameter and showed a significant numerical increase on BNT and RAVLT scores at 6- and 9-month visits. [0392] Efficacy data available from 5 subjects treated at the low dose level (Cohort 1) in the Phase 1 portion of the study suggest that NRTX-1001 treatment can significantly reduce seizure activity. The five subjects in Cohort 1 (low dose) had an average baseline seizure frequency of 32, 14, 26, 2, and 40 total seizures per month during the historical six-month baseline period, respectively, and have been followed for at least nine months after treatment. In the nine months since receiving NRTX-1001, these subjects had a median seizure reduction from baseline of 78% for all seizure events, including focal aware, focal impaired-awareness, and focal to bilateral tonic-clonic seizures (FIG. 41A-41B). In months 1-3, 4-6, and 7-9 after NRTX- 1001 administration, median seizure reduction from baseline was 82%, 82%, and 83%. 80% of subjects (4 of 5) achieved >50% seizure reduction from baseline, and 40% of subjects (2 of 5) achieved >90% seizure reduction from baseline in the first nine months after NRTX-1001 administration. In months 1-6 after NRTX-1001 administration, 40% of subjects achieved >75% total seizure reduction from baseline, increasing to 60% of subjects in months 7-9. Focusing on disabling seizures only, and excluding focal aware seizures without objective manifestations (auras), Subjects 102-001, 101-001, 115-001, 107-001, and 104-001 had a baseline average of 32, 2, 3, 2, and 10 disabling seizures per month, respectively. In the nine months since the five subjects in Cohort 1 received NRTX-1001, the median disabling seizure reduction from baseline was 73% (FIG. 41A-41B). In months 1-3, 4-6, and 7-9 after administration, median disabling seizure reduction from baseline was 67%, 83%, and 83%, respectively. In months 4-9 after NRTX-1001 administration, 80% of subjects achieved >50% disabling seizure reduction, and 40% of subjects responded with >90% disabling seizure reduction from baseline. Subjects 102-001 and 101-001 have been followed for 26 and 19 months, respectively. During months 7-12, which is the proposed post-administration efficacy evaluation period in the Phase 2 portion of the NTE001 study, Subjects 102-001 and 101-001 had a total seizure reduction from baseline of 97% and 99%, respectively, for all seizure types, with 97% and 100% total seizure reduction from baseline after month 13. During months 7-12 after NRTX-1001 administration, Subjects 102-001 and 101-001 reported disabling seizure reduction from baseline of 97% and 92%, respectively, with 97% and 100% reduction in disabling seizures after month 13. Subject 102-001 has been free of focal impaired awareness seizures since the first month after treatment, and Subject 101-001 has been completely seizure-free since the seventh month after NRTX-1001 administration. Subjects 102-001 and 101-001 have discontinued the immunosuppression regimen at approximately 12 months after NRTX1001 administration, as planned, and are reporting durable seizure reduction in the second year without any evidence of immunorejection or rebound in seizure frequency to date. In conclusion, data obtained to date provide preliminary clinical evidence for significant seizure reduction in participants with drug-resistant MTLE (FIG. 41A-41B). [0393] In conclusion, the preliminary clinical evidence emerging from Phase 1 of the ongoing NTE001 study suggests that NRTX-1001 reduced seizure activity without impairing cognition or triggering other serious adverse events. NRTX-1001 could effectively address a significant unmet need among patients with drug-resistant MTLE, a condition known for its debilitating impact on patients’ health. Example 31 Additional potential indications for NRTX-1001: Alzheimer’s disease [0394] Alzheimer’s disease (AD) is a neurodegenerative disorder characterized clinically by severe cognitive deficits and pathologically by amyloid plaques, neuronal loss, and neurofibrillary tangles. Abnormal amyloid β-protein (Aβ) deposition in the brain may be a major initiating factor in AD neuropathology. However, neural network activity is aberrantly increased in AD patients and animal models due to functional deficits in and decreased activity of GABA inhibitory interneurons, contributing to cognitive deficits. Moreover, AD patients and animal models are characterized by reduced γ-oscillations. These brain rhythms underlie key short and long-term memory processes. Targeting GABA inhibitory interneurons by transplantation may rescue cognitive impairment as well as alterations in neural activity seen in AD animals and patients. [0395] Feasibility experiments were performed to accomplish 3 goals: (1) identification and validation of an appropriate AD mouse model by demonstration of abnormal EEG and cognitive defects, (2) demonstration of transplanted human pallial interneuron persistence in two AD mouse models, and (3) a human interneuron cell transplantation efficacy study. In the first goal, two different transgenic AD models were identified, 5XFAD and TG2576, and their temporal deposition of amyloid plaques was validated, in which 5XFAD presented a fast accumulation in plaques (starting at 2-3 months of age) while TG2576 animals showed a slower progression (FIG. 42A-42B). In both models, human PSC-derived interneurons persist and migrate throughout the hippocampus of the two AD models (FIG. 43A-43B). In addition, the transplanted interneurons mature and integrate in an AD diseased environment as observed by the expression of synaptic markers. Interestingly, interneuron cell transplantation in the TG2576 model resulted in reduced plaque accumulation (FIG. 44A-44B) and rescued premature death of the AD mice (FIG. 45) when compared to vehicle-injected AD mice and non-transgenic (NCAR) mice. Moreover, when these TG2576 animals are monitored for EEG patterns during their resting phase, transplantation of hESC-derived interneurons into the hippocampus resulted in increases in gamma-oscillation power (FIG. 46A-46B), suggesting that NRTX-1001 human pallial interneuron cell therapy can rescue neuronal network activity defects in AD. Example 32 Additional potential indications for NRTX-1001: Neocortical focal epilepsy [0396] Focal cortical dysplasia (FCD) is a neurodevelopmental disorder that represents a major cause of refractory epilepsy. Currently, the only therapeutic option is surgical cortical resection, but only 30-50% of patients will achieve proper management of their seizures after surgery. Several studies have shown that mutations in genes of the PI3K- Akt-mTOR pathway have been associated with type II and III FCDs. Transplantation of hPSC-derived human pallial interneurons can be a therapy for drug-resistant focal seizures, as shown herein. Similarly, human pallial interneuron cell therapy may ameliorate epilepsy symptoms in FCD, which also has secondary generalized seizures of focal origin that, in many cases, are resistant to anti-epileptic drugs. [0397] Increasing mTORC1 activity during mouse development by local embryonic manipulation of PI3k-Akt pathway genes, such as Rheb, TSC1/2 and Depdc5, results in spontaneous convulsive seizures. In particular, in utero expression of a constitutively active form of Rheb (RhebS16H) in the medial prefrontal cortex (mPFC) results in a dose-dependent increase of seizures by 2-4 months of age (Becker and Beck 2018; Nguyen et al., 2019). Here two FCD models have been developed in immunocompromised mice. RhebS16H-expressing plasmids were either electroporated in utero into the mPFC at (E)mbryonic day 14.5 (Model 1: FIGs. 47A-48B) or injected with AAVs at (P)osnatal day 0-1 (Model 2: FIGs. 49A-50B). In the latter, AAVs expressed RhebS16H under the CamKII promoter to be expressed in excitatory neurons. At 2 months of age, animals were implanted with DSI electrodes and transmitters, and EEG was monitored for 2 weeks. In both models, epileptogenic activity with model 1 characterized by the presence of generalized seizures (FIG. 51A-51C) was identified, while model 2 presented only electrographic epileptiform activity (FIG. 52A-52B). Human pallial interneuron cell therapy may suppress seizures and epileptiform activity in FCD. Example 33 [0398] This example shows interneuron cell therapy to reduce pTau tangle pathology in a model of AD. [0399] A mouse model of Tau aggregation (P301S and/or P301L) is used. Animals are administered hESC-derived interneurons of the present disclosure. 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Wang L, Pang K, Zhou L, Cebrián-Silla A, González-Granero S, Wang S, Bi Q, White ML, Ho B, Li J, Li T, Perez Y, et al. A cross-species proteomic map reveals neoteny of human synapse development. Nature. 2023 Oct;622(7981):112-119. doi: 10.1038/s41586-023-06542-2. Epub 2023 Sep 13. PMID: 37704727; PMCID: PMC10576238. [0400] Although the foregoing has been described in some detail by way of illustrations and examples for purposes of clarity and understanding, it will be understood by those of skill in the art that modifications can be made without departing from the spirit of the present disclosure. Therefore, it should be understood that the forms disclosed herein are illustrative only and are not intended to limit the scope of the present disclosure, but rather to also cover all modification and alternatives coming with the true scope and spirit of the embodiments of the present disclosure. [0401] It is contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments disclosed above may be made. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like in connection with an embodiment can be used in all other embodiments set forth herein. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed subject matter. Thus, it is intended that the scope of the present disclosure should not be limited by the particular disclosed embodiments described above. Moreover, while the disclosed subject matter is susceptible to various modifications, and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the present disclosure is not to be limited to the particular forms or methods disclosed, but is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the various embodiments described and the appended claims. [0402] Any methods disclosed herein need not be performed in the order recited unless explicitly stated or context dictates otherwise. The methods disclosed herein include certain actions taken by a practitioner; however, they can also include any third-party instruction of those actions, either expressly or by implication. For example, actions such as “administering to the temporal lobe ipsilateral to the focal onset seizure a cellular composition” include “instructing the administration of a cellular composition to the temporal lobe ipsilateral to the focal onset seizure.” In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group. [0403] The ranges disclosed herein also encompass any and all overlap, sub- ranges, and combinations thereof. Language such as “up to,” “at least,” “greater than,” “less than,” “between,” and the like includes the number recited. Numbers preceded by a term such as “about” or “approximately” include the recited numbers. For example, “about 90%” includes “90%.” In some embodiments, at least 95% homologous includes 96%, 97%, 98%, 99%, and 100% homologous to the reference sequence. In addition, when a sequence is disclosed as “comprising” a nucleotide or amino acid sequence, such a reference shall also include, unless otherwise indicated, that the sequence “comprises”, “consists of” or “consists essentially of” the recited sequence. [0404] Terms and phrases used in this application, and variations thereof, especially in the appended claims, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing, the term ‘including’ should be read to mean ‘including, without limitation,’ ‘including but not limited to,’ or the like. [0405] All patents and other publications; including literature references, issued patents, published patent applications, and co-pending patent applications; cited throughout this application are expressly incorporated herein by reference for the purpose of describing and disclosing, for example, the methodologies described in such publications that might be used in connection with the technology described herein. These publications are provided solely for their disclosure prior to the filing date of the present application. Nothing in this regard should be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention or for any other reason. All statements as to the date or representation as to the contents of these documents is based on the information available to the applicants and does not constitute any admission as to the correctness of the dates or contents of these documents.

Claims

WHAT IS CLAIMED IS: 1. A method of treating seizure activity, comprising: identifying a subject in need of treating seizure activity; and administering to the subject a therapeutically effective amount of a cellular composition comprising pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1, and wherein a frequency of seizures is reduced after the administering, thereby treating the seizure activity.
2. The method of claim 1, wherein the subject has a focal epilepsy.
3. The method of claim 1, wherein the subject has a chronic seizure activity.
4. The method of claim 1, wherein the subject has mesial temporal sclerosis.
5. The method of claim 4, wherein the mesial temporal sclerosis is reduced after the administering
6. The method of claim 1, wherein the subject has an epileptogenic lesion in the brain.
7. The method of claim 6, wherein the epileptogenic lesion is reduced after the administering.
8. The method of claim 1, wherein at most 50% of the cells of the composition express NKX2-1.
9. The method of claim 8, wherein at most 40% of the cells of the composition express LHX8.
10. The method of claim 1, wherein the at least 50% of the cells of the composition further express at least one of MAF and MAFB.
11. The method of claim 1, wherein the therapeutically effective amount comprises about 5 x 104 cells or more.
12. The method of claim 11, wherein the therapeutically effective amount comprises between about 5 x 104 to about 1 x 1012 cells.
13. The method of claim 1, wherein the therapeutically effective amount of the cellular composition is administered at a concentration of about 1 x 105 cells/μL or greater.
14. The method of claim 1, wherein the cellular composition comprises sodium chloride at 100-600 mM.
15. The method of claim 14, wherein the cellular composition has an osmolality of at least 200 mOsm/kg.
16. The method of claim 1, wherein at most 40% of the cells express an MGE progenitor cell marker or a non-pallial MGE-type neural cell marker.
17. The method of claim 16, wherein at most 10% of the cells of the composition express KI67.
18. The method of claim 16, wherein at most 10% of the cells of the composition express OLIG2.
19. The method of claim 1, wherein cells of the composition are GABA-secreting cells.
20. The method of claim 1, wherein cells of the composition are migratory cells.
21. The method of claim 1, wherein at least 50% of the cells of the composition are pallial MGE-type GABAergic interneuron cells.
22. The method of claim 1, wherein the subject has temporal lobe epilepsy (TLE).
23. The method of claim 22, wherein the TLE is drug-resistant TLE.
24. The method of claim 1, wherein the subject suffers from a neocortical onset focal epilepsy.
25. The method of claim 1, wherein the subject suffers from focal seizure activity.
26. The method of claim 1, comprising administering the therapeutically effective amount of the cellular composition to the subject’s brain.
27. The method of claim 1, further comprising performing one or more of computed tomography (CT) scan, magnetic resonance imaging (MRI), MR spectroscopy (MRS), functional MRI (fMRI), electroencephalography (EEG), intracranial EEG, positron emission tomography (PET), and single photon emission computed tomography (SPECT) on the subject.
28. The method of claim 27, further comprising monitoring brain activity in the subject.
29. The method of claim 1, further comprising identifying a mesial temporal sclerosis in the subject, or one or more lesions in the brain.
30. The method of claim 29, wherein identifying the mesial temporal sclerosis in the subject or the one or more lesions comprises performing one or more of a CT scan, MRI, MRS, EEG, PET, SPECT, or fMRI.
31. The method of claim , wherein the frequency of seizures is reduced by about 50% or more after the administering.
32. The method of claim 1, further comprising performing one or more neurocognitive assessments of the subject.
33. The method of claim 1, wherein the cellular composition is a thawed cellular composition.
34. The method of claim 33, comprising holding the thawed cellular composition for up to about 5 days before administering to the subject.
35. The method of claim 34, comprising holding the thawed cellular composition at an ambient temperature of 2-18°C before administering to the subject.
36. The method of claim 33, further comprising thawing a cryopreserved cellular composition comprising the pluripotent stem cell-derived, pallial, MGE-type, GABAergic interneuron cells before administering.
37. The method of claim 1, wherein the administering comprises administering the cellular composition as one or more deposits in the subject’s brain.
38. The method of claim 37, wherein the therapeutically effective amount of the cellular composition is delivered in a volume of about 50 μL or less per deposit.
39. The method of claim 37, wherein the administering comprises administering the cellular composition to one or more sites in the temporal lobe, optionally wherein the one or more sites in the temporal lobe include the hippocampus, cortex, and/or amygdala, optionally wherein the one or more sites in the temporal lobe include the hippocampus, subiculum, entorhinal cortex, and/or parahippocampal gyrus.
40. The method of claim 1, wherein the cells are human cells.
41. The method of claim 1, wherein the subject is a human subject.
42. The method of claim 1, further comprising administering an immunosuppressant to the subject before and/or after administering the therapeutically effective amount of the cellular composition.
43. The method of claim 1, wherein the seizure activity is due to a traumatic brain injury, stroke, tumor, focal cortical dysplasia, tuberous sclerosis, developmental disorder, or a neurological disorder.
44. The method of claim 1, wherein the subject suffers from epileptic seizure-like discharges in the brain associated with Alzheimer’s disease, focal cortical dysplasia (FCD), or amnesic mild cognitive impairment (aMCI).
45. The method of claim 1, further comprising monitoring a therapeutic effect of administering the cellular composition in the subject.
46. The method of claim 45, comprising non-invasively monitoring the therapeutic effect using one or more biomarkers of seizure activity.
47. The method of claim 46, wherein the one or more biomarkers comprises N- acetylaspartate (NAA), myoinositol, glutamate, GABA, volume, edema, blood flow, oxygen metabolism, and glucose.
48. The method of claim 45, comprising using EEG, imaging, and/or one or more blood-based biomarkers to monitor the therapeutic effect.
49. A method of treating seizure activity, comprising: identifying a subject in need of treating seizure activity; and intracranially administering to the subject a cellular composition comprising: about 5 x 104 to about 1 x 1012 pluripotent stem cell-derived, pallial, MGE- type GABAergic interneuron cells at a concentration in a range of about 1 x 105 to about 4 x 106 cells/μL, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1, wherein 90% or more of the cells of the composition are post-mitotic cells; a poloxamer at 0.1-1%, v/v; and sodium chloride at 100-600 mM.
50. Use of a cellular composition for the treatment of seizure activity in a subject, the composition comprising pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and at least one of MAF and MAFB, optionally wherein at least 90% of the cells are post-mitotic.
51. A cellular composition comprising pluripotent stem cell-derived, pallial MGE-type GABAergic interneuron cells, for the preparation of a medicament for treatment of seizure activity in a subject, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1.
52. A therapeutic composition of pluripotent stem cell-derived pallial MGE-type GABAergic interneuron cells for the treatment of focal onset seizure, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1.
53. A therapeutic composition comprising: a poloxamer; and pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells at a concentration of about 1 x 105 cells/μL or greater.
54. A method of preparing a therapeutic composition for administering to a subject, comprising: providing pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells; and preparing a cellular composition comprising: a poloxamer; and the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells at a concentration of about 1 x 105 cells/μL or greater.
55. A delivery system for transplanting cells into a tissue, comprising: a delivery cannula comprising: a proximal portion comprising a cellular liquid composition comprising cells at a concentration of about 1 x 105 cells/μL or greater; and a distal portion comprising a cell-free liquid chase vehicle, wherein the cellular liquid composition is stably held in the proximal portion by the liquid chase vehicle; and a displacement device connected to a distal end of the cannula and configured to cause the liquid chase vehicle to displace the cellular liquid composition to thereby expel the cellular liquid composition from a proximal end of the cannula.
56. A delivery system for transplanting cells into a tissue, comprising: a delivery cannula comprising a cellular liquid composition comprising cells at a concentration of about 1 x 105 cells/μL or greater; and a displacement device connected to a distal end of the cannula and configured to displace the cellular liquid composition in the cannula to thereby expel the cellular liquid composition from a proximal end of the cannula.
57. The delivery system of claim 56, wherein the displacement device comprises a syringe, or a stylet traversing the inner lumen of the delivery cannula.
58. The delivery system of claim 57, further comprising a pump connected to the displacement device.
59. The delivery system of claim 58, wherein the cellular liquid composition comprises a contrast agent.
60. The delivery system of claim 59, wherein the contrast agent comprises an MRI contrast agent.
61. The delivery system of claim 60, wherein the contrast agent comprises a gadolinium-based contrast agent.
62. The delivery system of claim 59, further comprising a monitoring device configured to detect the position of the proximal end of the cannula at a site of delivery in a subject.
63. The delivery system of claim 62, wherein the monitoring device comprises a CT scanner, MRI scanner, PET scanner, or a SPECT scanner.
64. The delivery system of claim 56, wherein the cells are neuron cells.
65. The delivery system of claim 64, wherein the cells comprise pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells.
66. A method of treating seizure activity, comprising: identifying a subject in need of treating seizure activity; and administering to the subject a therapeutically effective amount of a cellular liquid composition comprising pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells using the system of any one of claims 55-65, wherein the cellular liquid composition comprises the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells.
67. The method of claim 66, comprising detecting the position of the delivery cannula in the subject’s brain during the administering.
68. The method of claim 67, wherein the detecting comprises using MRI to visualize the delivery cannula in the subject’s brain.
69. The method, therapeutic composition, or delivery system of any one of the preceding claims, wherein the cellular composition or the cellular liquid composition comprises NRTX-1001.
70. The method, therapeutic composition, or delivery system of any one of the preceding claims, wherein at least 50% of the cells of the composition express LHX6, ERBB4, and GAD1, and wherein at least 90% of the cells of the composition are post-mitotic cells.
71. The method, therapeutic composition, or delivery system of any one of the preceding claims, wherein at least 50% of the cells persisting in the subject retain a pallial, MGE-type GABAergic interneuron cell fate about 6 months or more after administration.
72. The method, therapeutic composition, or delivery system of claim 71, wherein the cells persisting in the subject and that retain the pallial, MGE-type GABAergic interneuron cell fate express one or more of GAD1, GAD2, LHX6, SOX6, NXPH1, ERBB4, SST, NPY, MEF2c, and ARX.
73. The method of claim 1, wherein the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells are genetically modified.
74. The method of claim 73, wherein the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells are genetically modified to reduce an immunological response against the administered cellular composition by the subject, optionally wherein the pluripotent stem cell-derived, pallial, MGE-type GABAergic interneuron cells comprises: a mutation in one or more immune-activating genes that reduces or abolishes expression or activity thereof; and/or a genetic modification that activates expression or activity of one or more immune-inhibiting genes.
75. The method of claim 74, wherein the pluripotent stem cell-derived, pallial, MGE- type GABAergic interneuron cells are genetically modified to reduce or abolish expression of one or more of: B2M, a HLA class I gene, and/or a HLA class II gene.
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