Figure 3. VWF structure is influenced by shear stress, flow acceleration and vessel curvature.
In this figure, all of the vessels shown were activated with phorbol myristate acetate (PMA) before being perfused with buffer. (a) VWF deposition in a vessel segment one-fourth of the diameter of the segment that immediately precedes it. The calculated shear stress in the narrower segment was ∼3 dyn cm−2. (b) VWF clumps formed in stenosed microvessels of small internal diameter with flow acceleration. Green: VWF and blue: nuclei. (c,d) z-projection of confocal images of a stimulated ‘UW' vessel. Red: CD31, green: VWF and blue: nuclei. (d) zoomed image of VWF structure near the narrowest region in (c), showing that the VWF clump blocks >50% of the vessel cross-sectional area. (e) (i) Wall shear rate in the U-shaped segment of the vessel, simulated with COMSOL. White lines: streamlines; colour: shear rate; and (ii) Schematic of VWF structures along the vessels when flow converges and diverges in the region of the curve. N >3 for each condition.