Platelet function testing in hirudin and BAPA anticoagulated blood

Background: Sodium citrate is the most commonly used anticoagulant for platelet function testing. However, the use of citrated blood for platelet function analysis has been criticized due to creation of a non-physiological milieu. Moreover, platelet function measurements performed with citrated blood need to be completed within 4 h after blood collection. Alternatively, hirudin and recently, a dual thrombin/factor Xa inhibitor benzylsulfonyl-D-Arg-Pro-4-amidinobenzylamide (BAPA), can be used to improve the reactivity after prolonged storage of platelets. The present study investigated platelet function tests using hirudin and BAPA anticoagulated blood. Methods: Blood was obtained from 30 healthy individuals and 20 patients on aspirin or clopidogrel therapy, and stored for 2, 12, 24 or 48 h. Light transmission aggregometry and impedance platelet aggregometry were performed using adenosine 5-diphosphate (ADP) and arachidonic acid as agonists. The vasodilator stimulated phosphoprotein (VASP) phosphorylation assay was evaluated. Results: Platelet aggregation measurements of healthy individuals and patients showed stable platelet aggregation values induced by arachidonic acid, after 24 h, when hirudin or BAPA anticoagulated blood was used. However, citrated blood resulted in significantly reduced platelet response after 12 h. ADP-induced light transmission aggregation of healthy individuals and patients exhibited unchanged platelet aggregation after 12 h using hirudin or BAPA anticoagulated blood, while significantly reduced platelet response was observed after 12 h when using citrated blood. In contrast, measurement of ADP-induced aggregation by use of impedance aggregometry resulted in reduced stability over 12 h using hirudin or BAPA anticoagulated blood. The VASP assay exhibited no significant changes in results over a storage period of 48 h, independent of the anticoagulants used. Conclusions: Use of hirudin or BAPA anticoagulated blood resulted in improvement of stability of platelet function measurements.