UV irradiation causes multiple cellular changes in cultured human retinal pigment epithelium cells

Background. The retinal pigment epithelium maybe causally involved in the development and progression of age-related macula degeneration; however, the mechanisms leading to the development of age-related macula degeneration remain largely unknown. The purpose of this study was to examine cellular changes in the retinal pigment epithelium induced by direct irradiation with UV light in culture. Methods. Retinal pigment epithelium cells from post-mortem human retinas were used to obtain dissociated cultures with cells retaining the ability to differentiate in vitro. These cells were cultured over several days to weeks. The UV radiation (UV-A and UV-B) occurred under sterile conditions with a 100 HBO/mercury bulb attached to a dissecting microscope, delivering co-axial illumination. The time dependence of irradiation effects was analysed using morphometric, immunohistochemical, functional and apoptosis-detecting techniques. Results. Vital and proliferating retinal pigment epithelium cell cultures could be prepared consistently. The cells showed tissue-specific morphologies in vitro for several days to weeks. Pigment epithelium-derived factor was detected in these cells using immunocytochemistry and Western blots. The UV irradiation but not white light resulted in measurable alterations of cell shape and size. The irradiated cells showed partial swelling and shrinkage reminiscent of progressing apoptotic degeneration. TUNEL staining revealed that apoptosis was induced by UV light, but not detectably by white light. The phagocytosis of fluorescent micro-particles diminished after irradiation. These effects were dependent on the duration of irradiation.<LF>Conclusions. Cultures of retinal pigment epithelium are suitable and sensitive models to study cell damage and may contribute to unravelling the pathogenetic mechanisms of retinal degeneration.