Induced Pluripotent Stem Cells Promote Retinal Ganglion Cell Survival After Transplant

PURPOSE: The purpose of this study was to characterize whether induced pluripotent stem cells (iPSCs) affect survival of grafted retinal ganglion cells (RGCs) after transplantation. METHODS: For in vitro studies, human iPSCs were either directly cocultured with mouse RGCs or plated in hanging inserts in RGC cultures for 1 week. For ex vivo studies, RGCs and iPSCs were seeded onto the inner surface of an adult rat retina explant and cultured for 1 week. For in vivo studies, RGCs and iPSCs were intravitreally coinjected into an adult rat eye 1 week before examining retinas by explant and immunostaining. RESULTS: A dose-dependent increase in RGC survival was observed in RGC-iPSC direct cocultures, and RGC-iPSC indirect cocultures showed a similar RGC protective effect, but to a lesser extent than in direct coculture. Enhanced RGC survival was also identified in RGC-iPSC cotransplantations to adult retinas ex vivo and in vivo. In addition, RGCs with iPSC cotransplantation extended significantly longer neurites than RGC-only transplants. CONCLUSIONS: Human iPSCs promote transplanted RGC survival and neurite extension. This effect may be mediated at least partially through secretion of diffusible neuroprotective factors.