Poster presentation, P13

Official XXIst International Pigment Cell Conference website - 21-24 Sept 2011, Bordeaux - France | updated: September 04 2011

Atomic force microscopy analysis of retinal pigment epithelium cells subjected to photodynamic stress

Retinal pigment epithelium (RPE) provides key metabolic support for the entire retina and is involved in biological renewal of photoreceptor outer segment (POS) membranes. Periodic phagocytosis of POS by RPE is critically important for proper function and survival of photoreceptor cells. Although melanin in normal human RPE contributes to visual acuity by absorption of light that could otherwise be reflected from the fundus and lead to spurious signals, the pigment may also play photoprotective and antioxidant functions. In this study, we analyzed inhibitory effects of oxidative stress, induced in cultured human ARPE-19 cells by photodynamic treatment, on the cell phagocytic activity and correlated the results with changes in morphology and nanomechanical properties of the cells examined with atomic force microscopy (AFM). Preliminary results of our study show that significant inhibition of phagocytic activity of ARPE-19 cells, induced by sub-lethal oxidative stress, is accompanied by dramatic changes in morphology of the cells. The modulatory effect of melanin in ARPE-19 cells, exposed to photodynamic stress, was analyzed by comparing survival of cells and their phagocytic activity before and after loading the cells with purified bovine RPE melanosomes. Our data indicate that cells containing phagocytized melanosomes were more resistant to photoinduced stress than cells containing control particles. This study has demonstrated that AFM is a method of choice for monitoring changes in morphology and nanomechanical properties of living RPE cells, under physiological conditions in vitro, in response to sub-lethal oxidative stress.

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