The Effects of Heparin Coating of Oxygenator Fibers on Platelet Adhesion and Protein Adsorption

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Abstract
Platelet adhesion on the cardiopulmonary bypass oxygenator membrane is associated with impaired hemostasis. We investigated the effects of heparin coating of the oxygenator membrane on protein adsorption and platelet adhesion on the surface. Noncoated and heparin-coated polypropylene membranes were incubated in whole blood with small- (1 U/mL) or large-dose (5 U/mL) heparin as an anticoagulant for 3 h at 37°C. The amount of platelets adhering on each fiber was assessed by using enzyme immunoassays using monoclonal antibodies directed against CD42b (GP Ib) and CD61 (GP IIb/IIIa). Platelet activation was assessed by measuring plasma guanosine monophosphate 140 levels. The amount and composition of the adsorbed proteins on the surface were analyzed by using a bicinchoninic acid protein assay and by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting technique. The heparin coating of the fibers significantly reduced platelet adhesion on the surface. However, platelet activation was reduced by heparin coating only with small-dose heparinization. The adsorption of platelet adhesive proteins such as fibrinogen and von Willebrand factor was not altered, whereas that of fibronectin was increased by heparin coating. We conclude that heparin coating of the oxygenator fibers can decrease platelet adhesion without affecting adsorption of major adhesive proteins. Surface heparin coating is associated with an increased fibronectin adsorption on the fibers. Implications Heparin coating can reduce platelet adhesion and activation in the presence of small-dose heparinization, potentially reducing the inflammatory response and activation of thrombosis and fibrinolysis.