A distinct lineage pathway drives parvalbumin chandelier cell fate in human interneuron reprogramming.

Direct lineage reprogramming of glial cells to induced neurons has the potential for restoring brain circuits and function in neuronal disorders and states. We introduce three-dimensional (3D) human glia reprogramming into neurons with a GABAergic interneuron phenotype using stem cell-derived human glia. Single-nucleus RNA sequencing of the converted cells demonstrates distinct neuronal clusters within 2 weeks, including a parvalbumin (PV) cluster with high neuronal maturity and features of chandelier interneurons. A lineage trajectory analysis of the glia-to-neuron conversion reveals a distinct lineage pathway to PV chandelier fate, including various neuronal developmental stages and the establishment of synaptic machinery. This analysis reveals PV fate-important genes that are previously unknown to neural reprogramming with promising functional importance for future derivations. Our data demonstrate successful human glia conversion into interneurons with features of bona fide PV subtype and highlight the reprogramming trajectory with key transitional genes. This advancement holds promise for future human brain cell engineering and repair.