Photobleaching of melanosomes from retinal pigment epithelium: II. Effects on the response of living cells to photic stress.

摘要: Melanosomes of the retinal pigment epithelium (RPE) are long lived organelles that may undergo photobleaching with aging, which can diminish antioxidant efficiency melanin. Here, isolated porcine RPE melanosomes were experimentally photobleached visible light to simulate aging and compared untreated granules or control particles (black latex beads) for their effects on survival photically stressed ARPE-19 cultures. Particles delivered cultures uptake by phagocytosis then cells exposed violet analyzed a new live cell imaging method identify time apoptotic blebbing as dynamic measure reduced survival. Results indicated did not decrease photic injury when lacking containing particles, might be expected if melanin performed an function. Instead showed earlier onset lower fraction surviving after stress. Cell was even further in photobleached, decreased increasing time. Photobleaching therefore makes them more sensitive light-induced cytotoxicity. This observation raises possibility aged increase stress situ, perhaps contributing tissue function degeneration adjacent retina supports. How (photobleached not) interact local subcellular environment modify is poorly understood likely determined physicochemical state granule its constituent The introduced here, permitted detection graded effect photobleaching, provides bioassay probing melanosome modifications.