Abstract
Abstract: :
Purpose: Oxidative stress in the macular retinal pigment epithelial (RPE) cells may play a role in the initiation of age-related macular degeneration (AMD). The purpose of this study was to compare the differential susceptibility to oxidative damage between macular and peripheral primary RPE cells harvested from human donor eyes. The effect of aging was also examined. Methods: Human eyes (n=19) were obtained within 48 hrs postmortum, with 13 eyes from 70-79 yr old donors (Group 1) and 6 from 80-89 yrs (Group 2). RPE cells from macular and peripheral regions were dissected and cultured. At confluence, cells were exposed to hydrogen peroxide (H2O2) at 50, 100, 200, 400 or 1000 uM for 1 hr. Mitochondrial redox function was measured by the MTT assay, and mtDNA damage and repair were examined by quantitative PCR. Control cells received no H2O2treatment. Results: Mitochondrial redox function significantly decreased (19.7%, p<0.05) in macular RPE cells exposed to 100 uM H2O2 relative to peripheral RPE in Group 1, but there were no significant differences in response to other concentrations of H2O2 between macular and peripheral RPE. Oxidatively-mediated mitochondrial dysfunction in macular RPE was even more apparent in Group 2, with 19-30% reduction compared to peripheral RPE (p<0.05) after exposure to 100-1000 uM H2O2. Both macular and peripheral RPE cells showed significant decreases (p<0.05) in mitochondrial redox function in Group 2 relative to Group 1 following exposure to 100 and 200 uM H2O2. DNA damage and repair assays are in progress. Conclusions: Macular RPE cells are more susceptible to oxidative stress than peripheral RPE, and this vulnerability appears to increase with age. These results may relate to the susceptibility of macular RPE to aging and acquired diseases, such as AMD.
Keywords: age-related macular degeneration • aging • retinal pigment epithelium