In vitro blood compatibility of heparin-immobilized polyurethane containing ester groups in the side chain

In a previous study, we reported on the synthesis of heparin-immobilized polyetherurethanes containing ester groups in the side chain. In this study, the blood compatibility of heparin-immobilized polyurethanes was investigated using in vitro plasma recalcification time (PRT), activated partial thromboplastin time (APTT), platelet adhesion and activation and peripheral blood mononuclear cell (PBMC) adhesion and activation. In the experiment with plasma proteins, the PRT of the polyurethane (PU) surface was prolonged by polyethylene oxide (PEO) grafting and further prolonged by heparin immobilization. The APTT was prolonged on the PU-C-H and PU-P-H, suggesting the binding of immobilized heparin to the antithrombin III. The percentage of platelet adhesion on the PU was almost the same as that on carboxylic acid-introduced PU (PU-C), but was slightly decreased by PEO grafting and further decreased by heparin immobilization. The release of serotonin from the adhering platelets was slightly suppressed on the PEO-grafted PU yet significantly suppressed on the heparin-immobilized PUs. In the PBMC experiments, the adhesion and activation of the cells were significantly suppressed on the heparin-immobilized PUs, and the amount of interleukin-6 (IL-6) released from the PBMCs stimulated with the surface-modified PUs decreased with a decrease in the PBMC adhesion.