Fig. 1

RPE cell sphere-derived stem cells (SDSCs) and their neural differentiation in vitro. a A schematic diagram showing SDSC production. RPE cells were adherently cultured to confluence, and the monolayer cultured cell sheet was scraped off the plate and resuspended in an ultralow culture dish (d0) where the cells initially formed aggregates and then spheres in 3 days (d3). These 3-day spheres were placed back into a culture plate coated with gelatin for up to a month to observe stem cell colony formation (see [17] for the detailed procedure). Different colors indicate the heterogeneous RPE-derived cell populations. b SDSCs were cultured in a photoreceptor differentiation medium for 20 days and then immunostained with the general neural cell marker nestin and c the rod photoreceptor marker opsin. d Their differentiation rates in the expression of nestin and opsin