Platelet adhesion and activation under static and flow conditions

Abstract

An investigation of platelet deposition and activation was carried out using E.C. reference materials (EUROBIOMAT program), applying static and flow test systems. The following materials were investigated: polyethylene (PE), polypropylene (PP), poly(vinyl chloride with di(ethylhexyl) phthalate as plasticizer (PVC-D) and pellethane (PEL). Platelet adhesion and activation were studied under non-flow conditions, applying a recently developed enzyme immunoassay (EIA) for the detection of the platelet proteins GP Ib and GMP 140, also known as PADGEM, after a 30 min incubation. Furthermore, how platelets adhere under laminar flow conditions was examined. These experiments were carried out with use of a capillary perfusion model in order to estimate the adhesion and activation of platelets in open and closed loop systems at a shear rate of 2000 s −1. The contact times between anti-coagulated whole blood and the test materials were from about 2 min for the open loop system to 20 rain for the closed loop system. As parameters, the retention of platelets and the release of β-thromboglobulin were measured. A modified EIA for GMP 140 was applied to obtain more insight into the distribution of platelets over the length of the tubes. It was shown that testing under non-flow conditions yielded comparable data to results obtained under flow conditions in the closed loop system. PE and PP exhibited low haemocompatibility compared with PVC-D and PEL, as indicated by the measurement of GP Ib and GMP 140 under static conditions. The investigation under flow conditions demonstrated generally the same sequence concerning platelet attachment and activation. However, it was shown that platelet retention and activation increased with contact time.