Abstract
Abstract: :
Purpose: Since studies have shown an intimate relationship between cholesterol and retinal diseases, we examined the effects of cholesterol oxides on cultured cells. Using the retinal precursor cell line R28 and the human RPE cell line ARPE-19 cells, we investigated the potential cytotoxicity of cholesterol oxides. Methods: Cultured R28 and ARPE-19 cells were treated with either 7- beta-OH- and 7-keto-cholesterol. Cell viability was determined by the WST-1 colorimetric assay and production of reactive oxygen intermediates (ROI) was assessed by a fluorescent probe-based assay (2',7'-dichlorodihydrofluorescein diacetate; H2DCFDA). Results: Both of the cholesterol oxides tested were toxic to the two cell lines used in this study. Treatment with either 7- beta-OH- or 7-keto-cholesterol resulted in over 75% cell death after 72 hours at a concentration of 20 ug/ml. There was time-dependency of oxysterol toxicity with approximately 25% cell death after 24 hours of exposure of the cholesterol oxides tested. The fluorescent assay for ROI production showed that after an hour of exposure to the cholesterol oxides, cells responded with increased levels of ROI. Conclusion: These in vitro findings provide evidence that cholesterol oxides can directly damage cultured retinal and RPE cells. The oxysterol-induced oxidative stress in these cells may be a factor in the pathology of retinal degenerative diseases.
Keywords: 554 retina • 567 retinal pigment epithelium • 458 lipids