Platelet Function Assay Using Dielectric Blood Coagulometry

The hemostatic function of platelets is complementary to blood coagulation. However, traditional platelet function tests have primarily focused on measuring platelet aggregation, reducing their clinical effectiveness for antiplatelet drug monitoring. To address this limitation, we propose a new test principle that evaluates platelet function and the effects of antiplatelet drugs through blood coagulation reactions. This principle was validated in model experimental systems using blood samples from healthy volunteers (n = 11), where antiplatelet drugs such as aspirin, prostaglandin E1, or ticagrelor were added to the blood samples. Ticagrelor was tested at four concentration levels, covering the expected therapeutic range. We found that the complementary function of platelets can be assessed by monitoring the 1 MHz dielectric permittivity during the blood coagulation process, particularly the peak value. When reagents such as agonists (arachidonic acid, collagen, or adenosine diphosphate ADP) and calcium were mixed into the citrated blood with turbulence by pipetting, platelets became activated and aggregated before thrombin generation, resulting in a "consumed" state of platelets. Consequently, the contribution to the permittivity peak was minimal. By contrast, when blood spiked with antiplatelet drugs was tested, agonist-induced platelet aggregation was inhibited during the initial stage of the measurement. However, after thrombin generation, platelets were activated through the thrombin receptor. These activated platelets interacted with fibrin, thereby affecting the permittivity peak. The results of this validation process with Student's t-tests confirm the fundamental operating principle of the proposed platelet function assay, thereby contributing to antiplatelet therapy monitoring.