Abstract 1444: Overexpression Of Endothelial Nitric Oxide Synthase Restores Post-natal Neovascularization In Atherosclerosis.

Abstract

Alteration in post-ischemic neovascularization is a common complication of atherosclerotic disease. This results, at least in part, from abrogation of bone-marrow mononuclear cells (BM-MNC) pro-angiogenic potential. Overexpression of eNOS has been shown to promote vessel growth in the setting of ischemia. We hypothesized that eNOS overexpression could restore impaired neovascularization in atherosclerotic (ApoE KO) mice. Hind limb ischemia was induced in mice by right femoral artery ligation. After two weeks we evaluated tissue perfusion of the foot by Laser Doppler, vessel density in the hind limb by micro-angiography and histology, and atherosclerotic plaque size. In vitro BM-MNC cell culture assays were performed. Tissue perfusion and vessel density were 1.5-fold increased in transgenic mice overexpressing eNOS (eNOStg) as compared to wild type (WT) (P<0.001, n=10). Transplantation of 1x106 WT- or eNOStg BM-MNC in WT recipients caused a 1.5-fold increase in tissue perfusion and vessel density compared to injection of PBS (P<0.001, n=10). Next, we used ApoE KO mice and crossbreeds of eNOStg and ApoE KO mice (eNOStg*ApoE KO). Tissue perfusion and vessel density were 1.8-fold increased in eNOStg*ApoE KO mice as compared to ApoE KO mice (P<0.001, n=10). Transplantation of both WT- or eNOStg*ApoE KO BM-MNC in ApoE KO recipients caused a 1.6- to 2-fold increase in tissue perfusion and vessel density compared to PBS (P<0.01, n=10), while transplantation of ApoE KO BM-MNC had no positive effect on neovascularization. Moreover, transplantation of WT BM-MNC significantly increased plaque size, while eNOStg*ApoE KO BM-MNC had no effect on plaque size. eNOS overexpression did not affect BM-MNC apoptosis and secretion of growth factors but increased their ability to differentiate in vitro into EPC. Conclusion: eNOS overexpression in the endothelium improves post-ischemic neovascularization in both physiological as atherosclerotic settings. Furthermore, eNOS overexpression in the bone marrow restores the impaired pro-angiogenic potential of atherosclerotic BM-MNC without adverse effects on plaque size. Therefore, overexpression of eNOS could play a vital part in the development of therapeutic angiogenesis for atherosclerotic disease.