Shear-induced platelet activation and adhesion on human pulmonary artery endothelial cells seeded onto hydrophilic polymers

We evaluated platelet activation and adhesion on two plasma polymerized sur faces, N-vinyl pyrrolidone (NVP) and gamma -butyro lactone (GBL), which hav e been shown previously to promote endothelial cell growth and adhesion as well as fibronectin-coated glass (1 mug/cm(2)) coverslips. Human pulmonary artery endothelial cells were seeded onto coverslips at a low density (simi lar to 20,000 cells/cm(2)) and grown to confluence (3-5 days). The material s, both with and without ECs, were then exposed to a shear rate of 400 in a closed loop recirculating flow system containing human platelet-rich plasm a. Plasma samples were taken at 0, 5, 15, 30, and 60 min and analyzed for p latelet and coagulation activation. The coverslips were examined for EC cov erage and Platelet adherence. EC retention over a 1-h perio was approximate ly 75% for all three materials. All three materials without ECs were highly platelet activating having similar P-selectin expression, platelet factor 4 (PF4) release, mepacrine uptake, and microparticle production. Both micro particle production and platelet adhesion were significantly lower in EC-se eded materials. Dense granule and PF4 release were both slightly diminished in all three materials seeded with ECs. P-selectin expression was reduced slightly for GBL, but remained the same for the other two materials. The EC -seeded materials displayed favorable characteristics with respect to plate let activation and adhesion; however, they still demonstrated some thrombog enic tendencies due to EC loss and exposure of the underlying substrate. Th erefore, both EC coverage and EC hemostatic function are important factors in determining the thromboresistance of an EC-seeded surface. (C) 2001 John Wiley & Sons, Inc.