Monocytes play an important role in collateral vessel formation (arteriogen
esis) by attaching to activated endothelium and by invading the walls of in
nate collateral vessels where they produce growth factors. Previous studies
have demonstrated that this process fan be promoted by several chemokines
and growth factors. In this study we examined the interaction between monoc
ytes and endothelium under stimulation of the angiogenic agent vascular end
othelial growth factor (VEGF). We report here the novel finding that VEGF s
timulates the expression of the alpha (L)-, alpha (M)- and beta (2)-integri
n monomers. In functional assays and by using neutralizing antibodies it wa
s shown that VEGF stimulates adhesion of monocytes to human umbilical vein
endothelial cells (HUVEC), and increased transmigration through endothelial
monolayers is dependent on interaction of monocyte B-2-integrins with its
endothelial counter ligand ICAM-1. Based on these in vitro data we hypothes
ize that the positive effect of VEGF on arteriogenesis may involve monocyte
activation.