Abstract
Purpose: :
Oxidative damage to the RPE cells is thought to play a major role in the development of Age–related Macular Degeneration (AMD). Oxysterols are oxygenated derivatives of cholesterol that act as key regulatory molecules in a variety of physiological and pathological processes. Recently, there have been several reports indicating that oxysterols, in particular 7–ketocholesterol, cause oxidative damage to retinal pigment epithelial cells (RPE). Others have previously demonstrated that the neurotrophic factors GDNF, BDNF, CNTF and PEDF protect photoreceptors from death in response to a number of insults in vivo. Here we evaluate the ability of these factors to prevent RPE cell death due to 7–ketocholesterol–induced oxidative damage.
Methods: :
Using the human RPE cell line, ARPE–19 as a model system, we have developed an in vitro survival assay using 7–ketocholesterol as a cell death induction signal. Oxidative damage and cell death was induced by the addition of 7–ketocholesterol, in the absence or presence of neurotrophic factors. WST–1 was used to measure cell viability following 24 hours of treatment with 7–ketocholesterol.
Results: :
ARPE–19 cells exposed to 7–ketocholesterol in the presence of GDNF, CNTF and PEDF exhibited significantly greater survival than cells exposed to 7–ketocholesterol alone. These factors demonstrated equal efficacy in their ability to protect ARPE–19 cells from 7–ketocholesterol toxicity (∼50% protection) but differed in potency with GDNF>CNTF>PEDF. BDNF (0.01–100 ng/ml) did not protect in this assay . We also did not observe any change in cell morphology or proliferation in response to treatment with GDNF, CNTF and PEDF alone at the concentrations found to be effective for protection.
Conclusions: :
: GDNF, CNTF and PEDF potently and significantly protect RPE cells from 7–ketocholesterol–induced oxidative damage in vitro. These neurotrophic factors, or compounds which regulate or mimic these proteins, may provide exciting new therapeutic strategies for the treatment of macular degeneration.
Keywords: protective mechanisms • growth factors/growth factor receptors • cell survival