Effect of Shear Stress on the Expression of Coagulation and Fibrinolytic Factors in Both Smooth Muscle and Endothelial Cells in a Co-Culture Model

Abstract

Blood vessels are subjected to forces due to the flow. Endothelial cells (EC) are recipients, cross-talk with smooth muscle cells (SMC), and regulate physiology. It was hypothesized that both EC and SMC respond to shear stress, which alters the expression of factors in coagulation and fibrinolysis. Methods: A co-culture of human saphenous vein EC (HSVEC) and human saphenous vein SMC (HSVSMC) was exposed to shear, following which the cells were separated. Gene expression of tissue factor, thrombomodulin (TM), plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA) were analyzed with real-time RT-PCR. Protein expression was studied with ELISA. In HSVEC, the expression of PAI-1 (×2.1), tPA (×1.8), uPA (×1.6), tissue factor (×2.5) and TM (×1.9) was upregulated after 4 h of shear compared to controls. After 24 h of shear, expression was still upregulated in tPA (×2.3) and TM (×1.6). In HSVSMC, change in expression of PAI-1 (×2.1) was present after 4 h and in uPA (×2.1), and TM (×0.4) after 24 h. Both HSVEC and HSVSMC responded to shear, which led to altered expression of coagulation and fibrinolytic factors. This indicates that SMC, and interactions between EC and SMC, are more important in the regulation of vascular wall hemostasis than earlier studies have reported.