Transplantation of autologous iris pigment epithelium to the subretinal space in rabbits

Background. Transplantation of autologous iris pigment epithelium (IPE) int o the subretinal space has been suggested as one approach for the treatment of age-related macular degeneration. Autologous rabbit IPE cells were tran splanted to the subretinal space to define the technique of transplantation and examine the survival of the transplanted cells. Methods. Autologous IPE cells were harvested by iridectomy and transplanted directly to the subretinal space of the fellow eye in 25 rabbits, using th e parsplana approach. Animals were killed over a period of 5 months, and th e retinas were examined morphologically by light and electron microscopy. Results. Autologous IPE cells survived and formed a polarized monolayer abo ve the retinal pigment epithelium in the subretinal space, with apical micr ovilli adjacent to photoreceptors. Fragments of phagocytosed photoreceptor rod outer segments were observed in phagosomes in the cytoplasm of IPE cell s. Adjacent rod outer segments remained healthy throughout the experimental period. No signs of a cell-mediated immunologic response were observed. Conclusions. Our results show that in rabbits, autologous IPE cells transpl anted to the subretinal space survive and do not adversely affect the photo receptors. These results suggest that in humans, IPE cells might provide a substitute for retinal pigment epithelium cells as autologous transplants f or the treatment of age-related macular degeneration.