[Long-term follow-up of allotransplantation of retinal pigment epithelial cells in rabbit with special reference to morphological studies].

Dysfunction as well as pathological changes of retinal pigment epithelium (RPE) has been implicated as the causes of some retinal diseases, including age-related macular degeneration, hereditary macular degeneration and retinitis pigmentosa, etc. Transplantation of normal healthy RPE cells with an attempt to treat the retinal diseases is one of the current interests in ophthalmic research. We have developed a modified pars plana technique including vitrectomy for subretinal transplantation of homologous, cultured, natural pigment labelled RPE cells in the non-pigmented rabbit. Our results, with follow-up from one week to one year, revealed that the transplanted RPE cells not only survived and attached to Bruch's membrane of the host eyes, but also had a distinct basal and apical morphology as seen in close contact with host photoreceptors, and formed junctional complexes with neighboring RPE cells. Close contact between the microvilli of the grafted RPE cells and the photoreceptor outer segments of the host was also observed. The normal periodical sheddings of the host outer segments were phagocytosed by the transplanted RPE cells, as demonstrated in our results. Furthermore, there was practically no, if any, sign of rejection found. All the results have demonstrated that the transplantation of RPE cells in rabbits was successful and these observations provide a reliable experimental evidence for the clinical research of allotransplantation of RPE cells.