Human iPSC-derived neural stem cells display a radial glia-like signature in vitro and favorable long-term safety in transplanted mice
Human induced pluripotent stem cell-derived neural stem/progenitor cells (hiPSC-NSCs) are a promising source for cell therapy approaches to treat neurodegenerative and demyelinating disorders. Despite ongoing efforts to characterize hiPSC-derived cells in vitro and in vivo, we lack comprehensive genome- and transcriptome-wide studies addressing hiPSC-NSC identity and safety, which are critical for establishing accepted criteria for prospective clinical applications. Here, we evaluated the transcriptional and epigenetic signatures of hiPSCs and differentiated hiPSC-NSC progeny, finding that the hiPSC-to-NSC transition results in a complete loss of pluripotency and the acquisition of a radial glia-associated transcriptional signature. Importantly, hiPSC-NSCs share with somatic human fetal NSCs (hfNSCs) the main transcriptional and epigenetic patterns associated with NSC-specific biology. In vivo, long-term observation (up to 10 months) of mice intracerebrally transplanted as neonates with hiPSC-NSCs showed robust engraftment and widespread distribution of human cells in the host brain parenchyma. Engrafted hiPSC-NSCs displayed multilineage potential and preferentially generated glial cells. No hyperproliferation, tumor formation, or expression of pluripotency markers was observed. Finally, we identified a novel role of the Sterol Regulatory Element Binding Transcription Factor 1 (SREBF1) in the regulation of astroglial commitment of hiPSC-NSCs. Overall, these comprehensive in vitro and in vivo analyses provide transcriptional and epigenetic reference datasets to define the maturation stage of NSCs derived from different hiPSC sources, and to clarify the safety profile of hiPSC-NSCs, supporting their continuing development as an alternative to somatic hfNSCs in treating neurodegenerative and demyelinating disorders.