VWF and deep vein thrombosis: In another study designed to understand the role of the ED in COVID-19 and PASC, plasma levels of two proteins released by activated endothelial cells, soluble P-Selectin (sP-Sel) (also released by activated platelets) and von Willebrand factor (VWF) antigen (measures amount of the clotting factor, VWF), and D-dimer (a biomarker of systemic thrombosis), were measured (Osburn et al., 2022).