Effects of allopurinol on free-radical-induced reduction of the proliferation of retinal pigment epithelial cells.

PURPOSE

To investigate the effects of allopurinol on free-radical-induced reduction of growth of retinal pigment epithelial (RPE) cells.

METHODS

Bovine RPE cells were seeded at a density of 1 x 10(5) cells/Petri dish (60 x 15 mm) containing 4 ml MEM-Earle plus 15% FCS plus antibiotics. Twenty-four hours after seeding, cultures were exposed to a free radical generating system hypoxanthine(HX)/xanthine oxidase (XO) (HX: 0.1 micromol/l; XO: 700 microU/ml) for 10 or 60 min. Thereafter, the cells were washed. After washing the cells, allopurinol was added at 500 or 1000 micromol. To evaluate the effect of the radical generating system one group was not washed after treatment ('no wash'). The cultures were divided into eight groups: (1) no treatment (control); (2) HX/XO, no wash; (3,4) HX/XO, washed after 10 or 60 min; (5,6) HX/XO, washed after 10 or 60 min, application of 500 micromol of allopurinol; (7,8) HX/XO, washed after 10 or 60 min, application of 1000 micromol of allopurinol. Cell counts were carried out 96 h post-seeding. The values are expressed as means +/- SE.

RESULTS

After 72 h (HX/XO, no wash), the radical generating system resulted in a significant decrease in cell growth as compared to controls. When being eliminated after 10 or 60 min, the radical generating system also led to significant decrease in the values as compared to controls. Allopurinol treatment: All therapy (scavenger) groups (4,5) were significantly different from the respective control group; following exposition to the radical generating system for 60 min, allopurinol showed significantly higher values when given at 1000 micromol as compared to 500 micromol.

CONCLUSIONS

The results demonstrate that allopurinol, when given at a scavenger dose (500-1000 micromol), can prevent free-radical-induced cell damage and stop chain reactions. Thus, the possible beneficial value of allopurinol on diseases with involvement of oxidative tissue damage, such as age-related macular degeneration, should be investigated further.