Summary
The media layer of the arterial cryo-cross sections, is defective for vWf-dependent
platelet adhesion. Exposure of the same layer by stripping off the most inner portions
of the vessel wall results in a highly thrombogenic surface. Stripping or balloon
dilation was applied to porcine arteries prior to functional assays. Cryosections
of treated or untreated arteries were perfused with porcine blood at 3350 s-1 and
platelet deposition was detected by indirect immunofluorescence. Following balloon
dilation, vWf-dependent platelet deposition increased; covering 9.08 ± 1.36% of the
total media surface area, this value for untreated vessels was 0.88 ± 0.14%. A 10-fold
increase was also found in the binding of vWf-coated fluorescent beads to the media.
In addition to mechanical procedures, treatment by serine-proteases like trypsin,
chymotrypsin and proteinase 3, or by chondroitinase ABC, but not by heparitinase also
resulted in a 7-10-fold increase in platelet coverage over the media. Collagen in
the media may be complexed with another vessel wall component shielding the vWf-binding
sites. Mechanical or biochemical processes unmask these sites, and increase the thrombogenicity
of the vessel wall.
Keywords
Vascular media - von Willebrand factor - platelets - proteoglycan - collagen
