Precoating expanded polytetrafluoroethylene grafts alters production of endothelial cell-derived thrombomodulators

Abstract

Although the use of extracellular matrix proteins to precoat small-caliber vascular grafts before endothelial cell seeding has been shown to improve cell attachment, proliferation, and adherence, the effect of precoating on the thrombomodulatory properties of the seeded cells is unknown. The use of vascular prostheses lined with confluent endothelial cell monolayers expressing optimal thromboresistant properties may enhance patency rates. In this study human saphenous vein endothelial cells were seeded onto expanded polytetrafluoroethylene (ePTFE) graft material, both unmodified and precoated with fibronectin, type I collagen, or fibronectin and type I collagen (fibronectin/type I collagen). After 3 days of in vitro cultivation, endothelial cell production of prostacyclin, tissue plasminogen activator, and plasminogen activator inhibitor was evaluated under basal conditions and after stimulation with arachidonate or thrombin. Production of tissue plasminogen activator by endothelial cells cultured on fibronectin-ePTFE was significantly greater compared with production by endothelial cells grown on noncoated or fibronectin/type I collagen-ePTFE under basal conditions (p values <0.01 and <0.05, respectively) and in response to thrombin (p values <0.002 and <0.003, respectively). Plasminogen activator inhibitor-1 production was not detected in any of the four experimental groups. Endothelial cells cultured on fibronectin-ePTFE also synthesized significantly more prostacyclin than endothelial cells grown on type I collagen- or fibronectin/type I collagen-ePTFE, under basal conditions (p values <0.02 and <0.01, respectively) and in response to arachidonate (p values <0.03 and <0.002, respectively) and thrombin (p values <0.003 and <0.002, respectively). Endothelial cells cultured on fibronectin- and fibronectin/type I collagen-ePTFE exhibited 100% coverage, whereas coverage was 82% and 14% on collagen precoated and unmodified ePTFE surfaces, respectively. Endothelial cells cultured on fibronectin-ePTFE show, in addition to complete cell coverage, enhanced antithrombotic and fibrinolytic properties.