Abstract
Purpose: :
The environmental light is believed to be a risk of age-related macular degeneration.The aim of this study was to examine phototoxicity by fluorescent light for cultured human retinal pigment epithelial (RPE) cells and to evaluate the cytoprotective effect of lutein.
Methods: :
RPE cells were cultured in the phenol red-free media containing lutein (0, 0.02, 0.05, 0.1, 0.2 µg/ml) and 0.01% Tween20. One group was cultured under fluorescent light (3000 lux) imitating daily light environment, and another in the dark. After 36 hours, the degrees of cell damage were assessed by MTS and LDH assays for cell viability and cell death, respectively. Apoptosis was quantified by dye-uptake bioassay which detects the alteration of cell membranes during apoptotic process.
Results: :
After 36 hours, the cells were changed in shape from polygonal to spherical and intercellular space was enlarged in the group cultured under the fluorescent light, however there were no remarkable morphological changes in the group cultured in the dark either with or without lutein. Compared to the controls, lutein at the concentration of 0.02-0.05 µg/ml increased cell viability (P<0.01, Bonferroni correction) and reduced cell death (P<0.05) under the fluorescent light. Lutein at the concentration of 0.1-0.2 µg/ml did not show significant effects on cell viability or cell death. By dye-uptake bioassay, decrease of apoptotic cells was detected in the culture containing 0.1 µg/ml lutein under the fluorescent light, suggesting that cytoprotective effect of lutein may be optimum in this concentration.
Conclusions: :
These results indicate that fluorescent light has cytotoxicity for RPE cells and induces cell death via apoptosis and that lutein protects RPE from the phototoxicity by fluorescent light. Our culture system is a good in vitro model to study the effect of fluorescent light on ocular cells.
Keywords: age-related macular degeneration • oxidation/oxidative or free radical damage • retinal pigment epithelium