Targeting Anti-Angiogenic VEGF 165 b-VEGFR1 Signaling Promotes Nitric Oxide Independent Therapeutic Angiogenesis in Preclinical Peripheral Artery Disease Models.

Nitric oxide (NO) is the critical regulator of VEGFR2-induced angiogenesis. Neither VEGF-A over-expression nor L-Arginine (NO-precursor) supplementation has been effective in helping patients with Peripheral Artery Disease (PAD) in clinical trials. One incompletely studied reason may be due to the presence of the less characterized anti-angiogenic VEGF-A (VEGF 165 b) isoform. We have recently shown that VEGF 165 b inhibits ischemic angiogenesis by blocking VEGFR1, not VEGFR2 activation. Here we wanted to determine whether VEGF 165 b inhibition using a monoclonal isoform-specific antibody against VEGF 165 b vs. control, improved perfusion recovery in preclinical PAD models that have impaired VEGFR2-NO signaling, including (1) type-2 diabetic model, (2) endothelial Nitric oxide synthase-knock out mice, and (3) Myoglobin transgenic mice that have impaired NO bioavailability. In all PAD models, VEGF 165 b inhibition vs. control enhanced perfusion recovery, increased microvascular density in the ischemic limb, and activated VEGFR1-STAT3 signaling. In vitro, VEGF 165 b inhibition vs. control enhanced a VEGFR1-dependent endothelial survival/proliferation and angiogenic capacity. These data demonstrate that VEGF 165 b inhibition induces VEGFR1-STAT3 activation, which does not require increased NO to induce therapeutic angiogenesis in PAD. These results may have implications for advancing therapies for patients with PAD where the VEGFR2-eNOS-NO pathway is impaired.