IMPACTS OF LOW DENSITY LIPOPROTEIN ON ADHESIVE MECHANICAL PROPERTIES OF ENDOTHELIAL CELLS AND COLLAGEN IV

Abstract

Cell adhesion refers to the adhesion between cells and cells, cells and extracellular matrices (ECMs). Adhesion is a main communication pathway in cell–cell and cell–ECM interactions. Higher concentrations of low density lipoprotein (LDL) may decrease the adhesive forces between endothelial cells and ECMs in blood vessels. This study aimed to investigate the influence of LDL on the adhesive mechanical properties between endothelial cells (ECs) and ECMs by using the micropipette aspiration technique and flow chambers. Human umbilical vein endothelial cells (HUVECs) were used in this study and the LDL was obtained from fresh human plasma. For micropipette aspiration experiments, ECs were digested into single-cell suspensions and were inoculated in the flow chamber, which was coated with 2 μg/ml of Collagen IV (Col IV) mixed with LDL at four concentrations of 0, 50, 100 and 150 μg/ml, respectively. The micropipette aspiration experiment started 30 min after incubation. For flow chamber experiments, the same mixture was applied on the coverslips. ECs were perfused by three different kinds of shear stress in the flow chamber of 12.0, 24.0, 36.0 dynes/cm2, respectively. The results indicated that the adhesive force of ECs on Col IV-coated chamber decreased as LDL concentration increased (P < 0.05). Furthermore, in the flow conditions, the adhesive-retention ratio of cells was significantly decreased as shear stress and LDL concentration increased (P < 0.05). The results indicated that the adhesive force between ECs and ECMs was dependent on LDL concentration. Higher LDL concentration results in lower adhesive force. The adhesive-retention ratio of cells was relevant to the effect of shear stress and the alteration of shear stress that could influence the adhesion of cells. Similar study may potentially aid to understand the results of future pharmacological studies in atherosclerosis.