Purpose: This investigation was carried out to ascertain whether oxygen free radicals can influence the growth behaviour and consecutive lipid peroxidation of retinal pigment epithelium (RPE) cells in vitro and whether scavengers can counteract these effects.
Methods: The experimental model was based on calf RPE cells. Hypoxanthine/xanthine oxidase (HX/XO) and superoxide dismutase/ catalase (SOD/CAT) served as the radical generating system and scavengers, respectively. The components were tested alone and in combination. Lipid peroxides were determined in culture supernatants by a thiobarbituric acid assay.
Results: Concentrations of up to 100 mumol/l of HX alone and 500/ 1000 microU of XO alone, as well as the application of the scavengers without the radical generating system (HX/XO), had no effect. Dose-related reduction of cell growth and increase of lipid peroxidation were found with HX/XO treatment (single dose of 500 and 1000 microU/ml 24 h after seeding). After application of 500 or 1000 microU/ml of XO, CAT, when given alone (1200 U/ ml), counteracted the effect of the radicals on cell growth and lipid peroxidation; SOD (300 U/ml) had no effect. A combination of SOD and CAT was no better than the effect of CAT alone.
Conclusion: The prevention of radical-induced reduction of cell growth and lipid peroxidation by scavengers supports trials of therapy using antioxidants and/or free radical scavengers for various ocular syndromes with RPE involvement.