Summary
A murine model of endothelial cell injury-based vascular thrombosis was used to test
the role of platelet-endothelial cell adhesion molecule-1 (PECAM-1, CD31) in blood
cell aggregate formation and vessel occlusion in vivo. Photochemically-induced thrombus formation was analyzed in detail using intravital
fluorescence microscopy of individual microvessels in cremaster muscle preparations
of CD31-deficient and wildtype mice. In venules, epi-illumination induced rapid thrombus
formation with first platelet deposition after 0.56 ± 0.11min and complete vessel
occlusion within 5.05 ± 0.45 min. In arterioles, thrombus formation was markedly delayed
with first platelet deposition after 3.03 ± 0.47 min and complete vessel occlusion
within 10.04 ± 1.26 min. Kinetics of thrombus formation in both venules (first platelet
deposition: 0.52 ± 0.1 min; vessel occlusion: 5.03 ± 0.52 min) and arterioles (first
platelet deposition: 3.06 ± 0.68 min; vessel occlusion: 10.02 ± 1.38 min) of CD31-deficient
mice was found almost identical compared with that in wildtype animals. Tail bleeding
time was 233 ± 24 s in wildtype and 243 ± 32 s in CD31-deficient mice. Moreover, CD31-deficient
and wildtype mice revealed comparable interaction of leukocytes to endothelium. This
study shows for the first time in vivo that CD31 is not critically involved in blood cell thrombus formation upon endothelial
cell injury.
Keywords
Blood cell aggregation - thrombosis - platelet - CD31 - fluorescence microscopy