Mechanisms of Platelet Capture Under Very High Shear

Arterial thrombus forms from the capture and accumulation of circulating platelets on a stenotic arterial wall. As the thrombus grows, the lumen becomes further stenotic with resulting elevated shear rates of up to 500,000 s⁻¹ as the blood velocities increase through the narrowed cross-section [1]. Increased blood velocities impart greater forces on platelets binding to a thrombus. These forces can increase to 100 times the strength of an individual GPIbα-vWFA1 bond (∼100 pN) [2]. The increased shear rates also require that the capture bonds be formed quickly before the platelet is swept away. Thus, the hemodynamic conditions require that a platelet be able to form bonds in very short timescales in order to adhere. In this study, we estimate the bond forces and capture times for platelet capture under high shear considering the biophysics of bonding at the micromechanics scale.