Preservation of platelet function on 2-methacryloyloxyethyl phosphorylcholine-graft polymer as compared to various water-soluble graft polymers

The chemical structures of water-soluble polymers grafted onto PE surfaces affect platelet function when the platelets contact the polymer surfaces. T o improve our understanding of this effect, this study sought to control th e blood/materials interaction on the surfaces of polyethylene (PE) by graft ing with various water-soluble polymers. Such polymers as poly(2-methacrylo yloxyethyl phosphorylcholine) (PMPC), poly(acrylamide) (PAAm), poly(N-vinyl pyrrolidone) (PVPy), and poly[monomethacryloyl poly(ethylene glycol)] (PMPE G) were grafted on low density PE sheets by photoinduced graft polymerizati on. Both the PE bags modified with water-soluble polymers and those nonmodi fied were prepared by heat processing. Activation of platelets after storag e in the PE bags was evaluated by measuring the cytoplasmic free calcium io n concentration ([Ca2+]i). The concentration of [Ca2+]i of platelets in con tact with the PE surface grafted with PMPC was the same as that of native p latelets and significantly less than that in contact with other PE surfaces grafted with water-soluble polymers. The number of adherent platelets was effectively decreased on PE surfaces grafted with PMPC and PMPEG, as compar ed with nontreated PE. The aggregation ability of platelets was also measur ed after storage of platelet-rich plasma in the PE bags. The PE surface gra fted with PMPC effectively maintained aggregation ability as compared with both the nontreated PE and with PE grafted with PAAm, PVPy, and PMPEG. It w as concluded that for preserving platelet function, PMPC was the most effec tive of these water-soluble polymers used for surface modification. (C) 200 1 John Wiley & Sons, Inc.