Growth modulation of retinal microvascular cells by early and advanced glycation products.

To investigate the possible implication of non-enzymatic glycosylation in the etiopathogenesis of the diabetic retinopathy, we studied the effect of early and advanced glycation products on the growth of retinal microvascular cells. Glucose modified products were obtained by incubating bovine serum albumin or fetal bovine serum with 0.5 M glucose for 10 (early glycation products: EG-BSA and EG-FBS, respectively) or 60 days (advanced glycation end products: AGE-BSA and AGE-FBS, respectively). Cell growth was assessed by cell counting and DNA content determination. EG-BSA or AGE-BSA significantly decreased pericyte proliferation after 8 days of culture (33 and 13% inhibition, respectively). Concerning endothelial cells, EG-BSA reduced proliferation to 40% whereas AGE-BSA increased it to 156% after 4 days of culture. The glucose-treated sera didn't exhibit the same growth effects, neither the EG-FBS nor the AGE-FBS significantly affected endothelial cell proliferation. Only the AGE-FBS showed a significant inhibitory effect on pericyte proliferation (40% inhibition). We conclude that retinal microvascular cell growth in vitro could be differently modulated by early and advanced glycation products. The inhibitory effect of AGEs observed on pericyte growth, suggests that glycoxidation could be implicated in the pericyte loss observed in diabetic retinopathy.