OBJECTIVESTo investigate the effects of glucose and free fatty acids (FFAs) on the proliferation and cell cycle of human vascular endothelial cells in vitro, and to examine whether the combined presence of elevated FFAs and glucose may cross-amplify their individual injurious effects.

METHODSCultured human vascular endothelial cells (ECV304) were incubated with various concentrations of glucose and/or FFAs (palmitate and/or oleate) for 24 - 96 h. Morphologic alterations were observed using a phase contrast microscope and an electron microscope. Inhibition of proliferation was measured by a colorimetric 3-[4, 5-dimethyl thiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay. Cell viability was determined using trypan blue exclusion. Distribution of cells along phases of the cell cycle was analyzed by flow cytometry.

RESULTSGlucose 15 or 30 mmol/L, palmitate (PA) 0.25 or 0.5 mmol/L, and oleate (OA) 0.5 mmol/L inhibited proliferation and accelerated death of endothelial cells in a dose-and-time-dependent manner. After treatment with elevated glucose and/or FFAs, the G(0)/G(1) phase cells increased, whereas S phase cells decreased, suggesting that high glucose and/or FFAs mainly arrested endothelial cells at G(0)/G(1) phase. The inhibitive rates of proliferation and population of dead cells in endothelial cells incubated with glucose plus FFAs (glucose 30 mmol/L + PA 0.25 mmol/L, glucose 30 mmol/L + OA 0.5 mmol/L, glucose 30 mmol/L + PA 0.25 mmol/L + OA 0.5 mmol/L) increased more markedly than those treated with high glucose or FFAs (PA and/or OA) alone.

CONCLUSIONBoth high ambient glucose and FFAs can inhibit proliferation and accelerate death of endothelial cells in vitro. These changes were cross-amplified in the combined presence of high levels of glucose and FFAs.