Widespread integration and survival of adult-derived neural progenitor cells in the developing optic retina

Adult rat hippocampus-derived neural progenitor cells (AHPC) show considera ble adaptability following grafting to several brain regions. To evaluate t he plasticity of AHPCs within the optic retina, retrovirally engineered AHP Cs were grafted into the vitreous cavity of the adult and newborn rat eye. Within the adult eye, AHPCs formed a uniform nondisruptive lamina in intima te contact with the inner limiting membrane. Within 4 weeks of grafting to the developing eye, the AHPCs were well integrated into the retina and adop ted the morphologies and positions of Muller, amacrine, bipolar, horizontal , photoreceptor, and astroglial cells. Although the cells expressed neurona l or glial markers, none acquired end-stage markers unique to retinal neuro ns. This suggests that the adult-derived stem cells can adapt to a wide var iety of heterologous environments and express some but not all features of retinal cells when exposed to the cues present late in retinal development.