Toxicity of sitosterol to human umbilical vein endothelial cells in vitro.

The pathogenesis of the early development of atherosclerosis in sitosterolaemia is unknown. The effect of sitosterol on vascular endothelial cells in vitro was investigated by culturing human umbilical vein endothelial cells in the presence of up to 0.7 mmol l-1 of sitosterol. Liposomes were used to supply the high sterol concentrations. Exposure to 0.7 mmol l-1 of sitosterol for 72 h caused contraction of the endothelial cells and increased release of intracellular lactate dehydrogenase. After 96 h incubation the cells were partly detached from the substrate. At this time-point 0.35 mmol l-1 of sitosterol also caused perturbation of the endothelial cells. However, we could not confirm previous reports that tissue plasminogen activator production was enhanced by sitosterol.