Relative Contributions of von Willebrand Factor and Platelets in High Shear

Platelets and von Willebrand factor (VWF) are recognized as important mediators of thrombosis at high shear rates, but their relative contributions are unclear. We employ a stenotic microfluidic test system to induce thrombus formation to occlusion on collagen at pathologic shear rates of 3500-6000 s -1 . To obtain blood analogs with reduced platelet and VWF concentrations, human whole blood was diluted with saline by 90% or 99% and hematocrit restored by adding washed red blood cells. Platelets and VWF were selectively restored to normal levels. Blood from patients with known von Willebrand disease (VWD) was also investigated with and without the addition of VWF to investigate the contribution of platelet VWF.