An in vitro cell culture system to study the influence of external pneumatic compression on endothelial function

Purpose: External pneumatic compression (EPC) is an effective means of prop hylaxis against deep venous thrombosis. However, its mechanism remains poor ly understood. Understanding of the biological consequences of EPC is an im portant goal for optimizing performance of the EPC-generating device and pr oviding guidance for clinical use. We present a new in vitro cell culture s ystem (Venous Flow Simulator) that simulates blood flow and vessel collapse conditions during EPC, and we examine the influence of these factors on en dothelial cell (EC) fibrinolytic activity and vasomotor function. Methods. An in vitro cell culture system was designed to replicate the hemo dynamic sheer stress and vessel wall strain associated with induced blood f low during different modes of EPC. Human umbilical vein endothclial cells w ere cultured in the system and subjected to intermittent flow vessel collap se, or a combination of the two. The biologic response was assessed through , changes in EC morphology and the expression of fibrinolytic factors tissu e plasminogen activator, plasminogen activator inhibitor type 1, profibrino lytic receptor (annexin II), and vasomotor factors endothelial nitric oxide synthase and endothelin-1 Results The cells remained attached and viable after being subjected to int ermittent pulsatile flow (F) and tube compression (C). In F and F + C, cell s aligned in the direction of flow after 6 hours. Northern blot analysis of messenger RNA shows that there is an upregulation of tissue plasminogen ac tivator expression (1.95 +/- 0.19 in F and 2.45 + 0.46 in FC) and endotheli al nitric oxide synthase expression (2.08 +/- 0.25 in F and 2.11 +/- 0.21 i n FC). Plasminogen activator inhibitor type 1, annexin II, and endothelin 1 show no significant change under any experimental conditions. The results also show that pulsatile flow, more than vessel compression, influences EC morphology and function. Conclusion: Effects on ECs of intermittent flow and vessel collapse, either individually or simultaneously, were simulated with an in vitro system of nerv design. Initial results show that intermittent flow associated with EP C upregulates EC fibrinolytic potential and influences factors altering vas omotor tone. The system will facilitate future studies of EC function durin g EPC.