Abstract
Abstract: :
Purpose: The AREDS (Age–Related Eye Disease Study) demonstrated that a formulation of vitamins and minerals could retard progression of ARMD. Two of the major components of this formulation are vitamins C and E. In order to explore the protective mechanism of these vitamins, we have studied the ability of these vitamins to reduce photooxidative stress in a cell culture model of human derived RPE cells. Methods: Experiments were performed with hTERT RPE, a human RPE cell line transfected with the telomerase gene and provided by the Geron Corp. Cells were grown in 24–well culture plates using standard culture conditions. Cells were treated by one hr incubation with vitamin C and trolox (a semi–soluble form of vitamin E), both singly and in combination, and in various concentrations. Oxidative stress was detected in the cells using 10 µM 2', 7'–dichlorofluorescin (DCFH, Molecular Probes). Photooxidative stress was induced by exposing the cells to the mixed 488.1 nm (55%) and 514.5 nm (45%) continuous wave emission of an Argon ion laser (180 mW/cm2) for 120 sec. Following laser exposure, the fluorescence in the cells was measured using a spectrofluorimeter. Results: Protection against oxidative stress was assessed as the percentage reduction in fluorescence in the treated cells compared to controls. Vitamin C (500 µM) and trolox (500 µM) both provided protection against photooxidation, 60.43% ± 6.59% (p<0.01), and 60.45% ± 10.32% (p<0.001) respectively, compared to control. The combination of 500 µM vitamin C and 500 µM trolox further enhanced the protective effect to 42.7% ± 5.6% (p<0.001) of the control. Conclusions: Vitamin C and trolox reduced intracellular oxidation induced by laser exposure. Because chronic light exposure is thought to be a risk factor for ARMD, this finding supports the use of nutritional antioxidant supplements for the treatment of ARMD. In addition, the cell culture model of laser induced photooxidative stress can serve as a system to test other antioxidants and investigate the molecular mechanism of oxidative stress.
Keywords: oxidation/oxidative or free radical damage • radiation damage: light/UV • retina