Enhancement of Ischemia-Induced Angiogenesis by eNOS Overexpression

Abstract

Abstract-It remains undetermined whether continuous endothelial nitric oxide (NO) overexpression exerts angiogenic action. We surgically induced hindlimb ischemia in transgenic mice overexpressing endothelial NO synthase in the endothelium (eNOS-Tg) and studied neocapillary formation, ischemia-induced vascular endothelial growth factor (VEGF) expression, cGMP accumulation, and Akt/PKB signaling. Laser Doppler imaging revealed a markedly increased recovery of blood perfusion in ischemic limbs of eNOS-Tg mice (44% increase) compared with that in wild-type mice. Angiography showed a marked increase in basal and ischemia-induced collateral vessel formation in eNOS-Tg mice. Basal capillary densities and tissue cGMP levels were increased in eNOS-Tg mice (1.8-fold and 1.6-fold versus wild-type mice, respectively). Ischemia-induced neocapillary formation and cGMP accumulation were markedly increased in eNOS-Tg mice (3.6-fold and 4.1-fold versus preischemia levels, respectively), whereas those in wild-type mice were much less (1.8-fold and 1.5-fold, respectively). Basal and time-dependent VEGF expression in ischemic muscles did not differ between eNOS-Tg and wild-type mice. Basal and VEGF-mediated Akt phosphorylation in aortas was similar between eNOS-Tg and wild-type mice. Aortic basal eNOS expression was increased 3.3-fold, and VEGF-mediated eNOS phosphorylation was markedly induced in aortas of eNOS-Tg compared with preischemia levels (4.2-fold), whereas much smaller changes were observed in wild-type mice (1.8-fold increase). Our study demonstrates that overexpression of eNOS protein causes a marked increase in neocapillary formation in response to tissue ischemia without affecting ischemia-induced VEGF expression or VEGF-mediated Akt phosphorylation.

Repeated Thermal Therapy Up-Regulates Endothelial Nitric Oxide Synthase and Augments Angiogenesis in a Mouse Model of Hindlimb Ischemia

“…12 We believe that eNOS up-regulation induced by repeated thermal therapy is caused by an increase in cardiac output and blood flow, which in turn results in increased shear stress, although thermal stimulation might up-regulate arterial eNOS directly. 13,17 Repeated thermal therapy increases cardiac output, shear stresses of the vessel wall and ultimately eNOS expression.…”

“…11 Amano et al demonstrated that transgenic mice overexpressing eNOS in the endothelium increased new capillary formation in response to tissue ischemia. 12 Namba et al reported that intramuscular injection of bovine eNOS plasmid induced therapeutic angiogenesis in a rat ischemic hindlimb model. 19 Thus, NO is a critical regulatory molecule for angiogenesis in response to tissue ischemia.…”

Endothelial Nitric Oxide Synthase Overexpression Restores the Efficiency of Bone Marrow Mononuclear Cell-Based Therapy

“…In eNOS-deficient mice neovascularization is decreased, resulting in severe limb loss 14 ; in parallel, up-regulation of eNOS activity by eNOS gene delivery 15 or bovine eNOS overexpression 16 enhances postischemic blood flow recovery and limb function. In our study we confirmed these findings in healthy mice and extended them to a more clinically relevant model, the diabetic and atherosclerotic mouse.…”

Angiogenesis Induced by Endothelial Nitric Oxide Synthase Gene Through Vascular Endothelial Growth Factor Expression in a Rat Hindlimb Ischemia Model

“…Stimulation of neovascularization induced by NO might be due to induction of VEGF, although enhancement of ischemia-induced angiogenesis by eNOS overexpression was reported not to be dependent on VEGF in transgenic mice. 35 Continuous expression of NO might work, as angiogenic factors use other pathways. In addition, stimulation of new vessel formation by eNOS is likely to create new therapeutic options in angiogenesisdependent conditions such as wound healing, ischemic Figure 5.…”