Human inhibitory interneuron cell therapy for chronic focal epilepsy

Mesial temporal lobe epilepsy (MTLE) is the most common type of focal seizure disorder. In MTLE, seizures typically originate from a sclerotic hippocampus. Approximately one-third of patients do not respond to anti-seizure drugs and have few effective therapeutic options. Surgery to resect or ablate the affected temporal lobe is one such option, but it is not indicated or adequate for all individuals and can have adverse effects. Here, we report the development of an alternative cell therapy strategy for drug-resistant MTLE. The cell therapeutic is derived from a clinical-grade human embryonic stem cell line, and composed of cryopreserved post-mitotic medial ganglionic eminence (MGE)-type GABAergic inhibitory neurons of a predominantly pallial interneuron lineage. Single-dose intrahippocampal delivery of cryopreserved human pallial interneurons in a chronic mouse model of drug-resistant MTLE resulted in consistent and stable suppression of mesiotemporal seizures, with most animals becoming seizure-free. The grafted human interneurons distributed locally, matured, and persisted in the sclerotic hippocampus throughout the 8.5-month study. Pathological hallmarks of MTLE, such as hippocampal granule cell dispersion and sclerosis, were significantly reduced, and epileptic animal survival rates increased, after administration of the human interneurons. Suppression of seizure activity and amelioration of neuropathology were dose-dependent and suggested a broad therapeutic dosing range. No ectopic tissue or teratoma formation was detected after cell transplantation. Furthermore, behavioral abnormalities were not observed at any dose on a battery of assays. These findings support further development of human pallial MGE-type GABAergic interneuron cell therapy for the treatment of drug-resistant focal epilepsies. Overall design: A clinical-grade human embryonic stem cell line (D0) was used for differentiation. They are differentiated into neuronal progenitors first (D14), then into MGE interneurons. Nine batches of differentiation were made and their cell compositions were analyzed by using 10X Genomics scRNA-seq platform.