Growth of bovine retinal pericytes and endothelial cells in high hexose concentrations

Selective loss of capillary pericytes occurs early in diabetic and galactosemic retinopathies, at a stage when endothelial cells are still spared. To ascertain whether such loss is directly related to high hexose concentrations, the replication of bovine retinal pericytes and endothelial cells was studied by culturing them in media containing 5.6 mmol/l glucose alone and enriched with extra glucose, mannitol or galactose to achieve final concentrations of 16.7, 27.8 and 50.0 mmol/l. At the end of the incubation there were significantly less pericytes/culture cell in 16.7 mmol/l glucose (341 +/- 78 x 10(3), mean +/- SEM, p = 0.027) and galactose (304 +/- 55 x 10(3), p = 0.046) than in 5.6 mmol/l glucose (417 +/- 98 and 355 +/- 75 x 10(3) for separate experiments, respectively). Mannitol had no such effect (343 +/- 52 vs. 337 +/- 52 x 10(3). Endothelial cells did not change in number, except in 50.0 mmol/l glucose (533 +/- 66 vs. 629 +/- 67 x 10(3) at 5.6 mmol/l; p = 0.026) and 50.0 mmol/l galactose (440 +/- 48 vs. 592 +/- 51 x 10(3); p = 0.013). To verify if these effects are due to decreased replication, the uptake of 3H-thymidine was measured in pericytes and endothelial cells subjected to the same concentrations of glucose, mannitol and galactose. In pericytes, thymidine uptake was reduced in the presence of 16.7 mmol/l glucose (p = 0.003, compared to 5.6 mmol/l) and galactose (p = 0.027) but not mannitol. Pericyte counts and thymidine uptake was reduced for concentrations of glucose, galactose and mannitol higher than 16.7 mmol/l.(ABSTRACT TRUNCATED AT 250 WORDS)