Summary
Fibrillar collagen serves as a thrombogenic surface for platelet adhesion mediated
by von Willebrand factor (vWf) at high shear. Although abundant throughout the arterial
wall, vWf-dependent platelet deposition to artery cross-sections from perfused citrated
blood is localized to the adventitia of the vessel wall. Here we describe a similarly
skewed distribution of vWf-binding sites in artery cross-sections. Binding of vWf-coated
fluorescent beads, as well as detection of plasma vWf bound to artery cross-section
at 3350 s−1 shear rate with indirect particle-immunofluorescence or immunoelectron microscopy
demonstrate vWf binding sites in the adventitia, but not in the media. A monoclonal
anti-vWf antibody that interferes with vWf-binding to collagen in a microplate ELISA
inhibits vWf-binding to both the adventitia and sections of collagen fibrils. Our
data suggest that the media, despite its fibrillar collagen content, evidenced by
electron microscopy, is defective for vWf-binding, which may explain its thromboresistant
nature at high shear rates.
Keywords
Willebrand - collagen - adhesion - platelet - media