Human stem cell-derived GABAergic interneuron development reveals early emergence of subtype diversity and gradual electrochemical maturation.

Medial ganglionic eminence-derived inhibitory γ-aminobutyric acid (GABAergic) pallial interneurons (MGE-pINs) are essential regulators of cortical circuits, and their dysfunction is associated with neurological disorders. We developed human MGE-pINs from pluripotent stem cells for the treatment of drug-resistant epilepsy. Here, we analyzed xenografted MGE-pINs from human pluripotent stem cells (hMGE-pINs) over the lifespan of host mice in healthy and epileptic environments using single-nuclei RNA sequencing. Comparative transcriptomics against endogenous human brain datasets revealed that 97% of grafted cells developed into somatostatin (SST) and parvalbumin (PVALB) subtypes, including populations that exhibit selective vulnerability in Alzheimer's disease. Transplanted hMGE-pINs demonstrated rapid emergence of subclass features, progressing through distinct transcriptional states sequentially involving neuronal migration, synapse organization, and membrane maturation. We present molecular, electrophysiological, and morphological data that collectively confirm the derivation of diverse bona fide human SST and PVALB subtypes, providing a high-fidelity model to study hMGE-pIN development as well as a compositional atlas for regenerative cell therapy applications.