Low Density Lipoprotein Decrease Adhesion of Vascular Endothelial Cells Exposed to Fluid Shear Stress

Abstract

In this study, we investigated the effect of low density lipoprotein (LDL) on endothelial cell adhesion in shear stress. The endothelial cells were incubated with four different concentrations of low density lipoprotein for 24h. Thereafter, the content of cholesterol ester in endothelial cells was assayed with High Performance Liquid Chromatography (HPLC). The lipid within endothelial cells was detected with oil red O. F-actin was examined with fluorescence staining of rhodamine-phalloidin. A micropipette aspiration technique was employed to investigate the viscoelasticity of endothelial cells treated by LDL. After treated with LDL, endothelial cells were subjected to flow shear stress of 15Pa for 24h. Compared to control, LDL significantly increased the ester level in endothelial cells (p<0.05). Observation by fluorescence microscopy showed that the fibers of F-actin in normal endothelial cells concentrated along the cell membrane and no dense fibers were observed in the cytoplasm. The abnormal F-actin were appeared in LDL-treated endothelial cells, while most of the peripheral fibers disappeared and dense stress fibers were observed in the cytoplasm with high dose LDL. After exposed to 1.5 Pa shear stress the conformance and the adhesion of endothelial cells which incubated with 150 mg/L LDL decreased comparing with control. It is concluded that LDL causes lipid accumulation and the cytoplasm damaged, which may relate to endothelial cell conformance and adhesion.