The effect of shear rate on the adhesion/activation of human platelets in flow through a closed-loop polymeric...

Three polymers, produced as reference materials of a European Communities program, namely PE, PP, and PVC, in tubular form, were comparatively evaluated for their hemocompatibility. In particular, the following parameters: platelet retention index, beta-thromboglobulin (beta-TG) release from activated platelets, and expression of the platelet protein GMP 140 (PADGEM) were measured as a function of time for whole anticoagulated human blood flowing in a closed-loop system under two different shear rates of 2000 and 500 s-1. Data up to 20 min (afterwards there was hemolysis) showed a fluctuating platelet retention index as time increased for PE and PVC and an increasing value for PP. Platelet aggregation and dislodgment from the surface could not be differentiated. Activation of platelets as expressed with beta-TG release were higher for both PE and PP in both shear rates in comparison to PVC which elicited a higher response at the high shear rate. Finally, PADGEM estimations seem to indicate a more stable platelet retention layer for PP than PE or PVC.