Transplantation of IPE cells slows down degeneration of the photoreceptors in the RCS rat. This photoreceptor-sparing effect by the IPE cells was observed even when the transplants were predominantly located within the choroid. The beneficial effect observed may be related to trophic factors possibly secreted by the transplanted IPE cells.
These findings suggest that although IPE cells are able to phagocytize ROS, their ability to degrade them may be lower than in RPE cells. The increase of lipofuscin-like fluorescence is not due to the accumulation of lipofuscin-like granules.
Light or enzymatically induced lipid peroxides can be localized ultrastructurally due to their ability to react with tetramethylbenzidine and osmium in the absence of H2O2 to an electron-dense reaction product. Lipid peroxides seem to be removed from the RPE via Bruch's membrane and blood vessels. Disturbance of this pathway may enhance lipofuscin or drusen formation.
Our study was performed to test the hypothesis that subretinally injected protein can induce melanogenesis in the retinal pigment epithelium (RPE). Rod outer segments (ROS) were isolated from cattle eyes and injected into the subretinal space of Long Evans rats. Five days after surgery, the injected eyes were investigated by electron microscopy. The number of early-stage melanosomes and small melanin granules was compared in injected and noninjected eyes. It was found that the injected ROS were phagocytized by the RPE cells, and the number of early-stage melanosomes in the RPE was significantly increased in injected eyes compared to eyes without injection. The ROS-containing endosomes fused with melanolysosomes in which melanogenesis took place. The increased number of early-stage melanosomes indicates new formation of melanin.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.