INDUCTION OF VASCULAR ENDOTHELIAL GROWTH-FACTOR IN BALLOON-INJURED BABOON ARTERIES - A NOVEL ROLE FOR REACTIVE OXYGEN SPECIES IN ATHEROSCLEROSIS

Neovascularization is a hallmark of neointimal formation in atheroscle rotic plaques and restenotic lesions. Vascular endothelial growth fact or (VEGF) promotes neovascular growth, whereas oxidative stress is a p otent factor in vascular cell proliferation. To investigate the mechan isms of neovascular formation, we treated human and rat vascular smoot h muscle cells (VSMCs) with H2O2. Northern blot analysis demonstrated a dose- and time-dependent increase in VEGF mRNA, with a maximum of 4- fold at 3 hours (200 mu mol/L). As determined by immunoblotting and en zyme-linked immunosorbent assay, VEGF protein expression and secretion were similarly increased. Human umbilical vein endothelial cells were treated with conditioned medium from VSMCs incubated with 200 mu mol/ L H2O2. DNA synthesis, measured by thymidine incorporation, was increa sed 4-fold compared with control, an effect that was blocked by a neut ralizing anti-VEGF antibody. The lipid peroxidation product 4-hydroxyn onenal (1 mu mol/L), an endogenous reactive oxygen species present in human atherosclerotic lesions, also increased VEGF secretion in VSMCs in a similar time-dependent fashion. Immunohistochemical staining and in situ hybridization of aortic sections from balloon-injured baboons demonstrated increased VEGF expression in discrete areas of the neoint ima and media compared with control sections, and expression correlate d with the generation of 4-hydroxynonenal. Regulators of VEGF expressi on, such as reactive oxygen species, may enhance neovascularization of atherosclerotic and restenotic arteries.