Dai G, Tsukurov O, Orkin RW, Abbott WM, Kamm RD, Gertler JP.
An in vitro cell culture system to study the influence of external pneumatic
compression on endothelial function.

Division of Bioengineering and Environment Health, Massachusetts Institute of
Technology and the Vascular Surgery Laboratory, Division of Vascular Surgery,
Massachusetts General Hospital, Boston, MA 02114, USA.

PURPOSE: External pneumatic compression (EPC) is an effective means of
prophylaxis against deep venous thrombosis. However, its mechanism remains poorly
understood. Understanding of the biological consequences of EPC is an important
goal for optimizing performance of the EPC-generating device and providing
guidance for clinical use. We present a new in vitro cell culture system (Venous
Flow Simulator) that simulates blood flow and vessel collapse conditions during
EPC, and we examine the influence of these factors on endothelial cell (EC)
fibrinolytic activity and vasomotor function. METHODS: An in vitro cell culture
system was designed to replicate the hemodynamic shear stress and vessel wall
strain associated with induced blood flow during different modes of EPC. Human
umbilical vein endothelial cells were cultured in the system and subjected to
intermittent flow, vessel collapse, or a combination of the two. The biologic
response was assessed through changes in EC morphology and the expression of
fibrinolytic factors tissue plasminogen activator, plasminogen activator
inhibitor type 1, profibrinolytic receptor (annexin II), and vasomotor factors
endothelial nitric oxide synthase and endothelin-1. RESULTS: The cells remained
attached and viable after being subjected to intermittent pulsatile flow (F) and
tube compression (C). In F and F + C, cells aligned in the direction of flow
after 6 hours. Northern blot analysis of messenger RNA shows that there is an
upregulation of tissue plasminogen activator expression (1.95 +/- 0.19 in F and
2.45 +/- 0.46 in FC) and endothelial nitric oxide synthase expression (2.08 +/-
0.25 in F and 2.11 +/- 0.21 in 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 new design. Initial results show that
intermittent flow associated with EPC upregulates EC fibrinolytic potential and
influences factors altering vasomotor tone. The system will facilitate future
studies of EC function during EPC.