Quantitative investigation of platelet aggregation under high shear force for anti-platelet aggregation in vitro tests.

Blood pumps are often used for hemofiltration in patients with renal failure. To design effective centrifugal blood pumps for hemofiltration, it is important to suppress clogging caused by platelet aggregation. However, the optimal conditions for conducting anti-platelet aggregation tests in vitro have not yet been established. This study aimed to quantify the effect of the shear loading value and shear loading time on platelet aggregation and determine the optimal conditions for anti-platelet aggregation testing in vitro. To quantitatively evaluate platelet aggregation in terms of the negative logarithm-platelet aggregation threshold index (NL-PATI), which reflects the propensity of residual platelets to aggregate after shear loading, the following parameters were examined: blood collection method (collected from porcine vein using a syringe or collected from a slaughterhouse), type of anticoagulant (sodium citrate or heparin), shear rate, and shear time. The results showed that platelet aggregation in porcine blood increased under a high shear load applied at shear rates of approximately 20,000 s-1 or higher for 30 s. Platelet aggregation propensity was 2-3 times higher in heparin-anticoagulated blood than in sodium citrate-anticoagulated blood. Moreover, platelet aggregation was 1.5-2 times more in blood collected from the slaughterhouse than in syringe-collected blood. Testing with an integrated shear time of 30 s or less in relation to the total blood volume may be effective for conducting in vitro circulation experiments using hemofiltration blood pumps. The conditions established in this study may be useful for hemocompatibility testing of cardiovascular devices based on NL-PATI.