Modeling the processes of transendothelial transport of LDL and macrophage migration

Atherosclerosis is a multifactorial process involving various pathological mechanisms: inflammation, lipoprotein modification, cholesterol accumulation, endothelial dysfunction, oxidative stress and formation of atherosclerotic plaque. The main participants in the development of this disease are endothelial cells, leukocytes and smooth muscle cells of intima. The adult endothelium contains heterogeneous cells, including typical endothelial cells (TEC) and giant multinucleated EC variants (MVEC). The process of passing molecules is called transendothelial transport (TET). The purpose of this work is to model the processes of TET of low-density lipoproteins (LDL) and monocyte migration using various EC variants. In the study, a human EC line (EA.hy926) was used. Multicore variants of EC (MVEC) were obtained by treating EC with a 50% solution of polyethylene glycol 6000. To study LDL transcytosis and monocyte migration, tablets with inserts (0.4 or 3.0 micron pore diameter, respectively) forming a two-level system were used. The LDL transmission rate was assessed by measuring the amount of cholesterol in the upper and lower chambers every 2, 5 and 24 hours. A modified Folch method was used to measure the amount of cholesterol. The cholesterol content was adjusted according to the total protein level in the well, measured by the Lowry method. The migration of macrophages was estimated by direct counting of cells. The content of internalized cholesterol in the MVEC was statistically significantly higher than in the EC. The rate of LDL transport did not differ. The rate of passage of the endothelial barrier formed by MVEC by macrophages was higher at points 2 and 5 hours. After 24 hours the number of migrated cells did not differ. The rate of transendothelial transport for typical and multinucleated variants of EC did not statistically differ. Although the presence of MBEC does not affect the transport of lipoproteins into the subendothelial layer, the fact that multinucleated cells accumulate lipid droplets more actively than typical ECS may indicate an important role in the pathogenesis of atherosclerosis. The rate of macrophage migration after 2 and 5 hours was higher for MVEC than for TEC, whereas immature macrophages did not migrate through the endothelial barrier for 24 hours.