Abstract 18374: Secretoneurin Gene Therapy Improves Hindlimb and Cardiac Ischemia in Apo E -/- mice Without Influencing Systemic Atherosclerosis

Abstract

Background: Hypercholesterolemia (HC) is a major risk factor for the development of cardiovascular diseases and associated with reduced neovascularization in response to ischemia. Recent studies showed up-regulation of secretoneurin (SN) by hypoxia and reported induction of angio-, arterio- and vasculogenesis in the hindlimb ischemia (HLI) model. The aim of this study is to evaluate the therapeutic effect of SN in a condition associated with impaired vascular response. Methods/Results: SN stimulated capillary tube formation, proliferation and activation of ERK1/2 and Akt in umbilical vein endothelial and coronary artery endothelial cells (CAEC) in the presence of 50 microg/ml oxidized LDL (oxLDL) comparable to VEGF (rel. capillary tube formation CAEC: SN 1.56±0.05 vs. VEGF 1.63±0.09, n=4, P<0.01 vs ctr). To assess a therapeutic effect of SN in-vivo Apo E -/- mice set on western diet underwent HLI by ligation of the femoral artery or myocardial infarction (MI) by ligation of the left anterior descending artery. SN-plasmid (p-SN) or control-plasmid (p-ctr) was injected in the ischemic adductor muscle or the infarct border zone. In the HLI-model SN-therapy increased capillary (capillaries/HPF 200x: p-SN 354.6±14 vs. p-ctr 204.8±8.6; P<0.001) and arteriole (arterioles/HPF 200x: p-SN 5.6±0.52 vs. p-ctr 3.1±0.24; P<0.001) density and improved limb perfusion, assessed by laser Doppler perfusion imaging (rel. LDPI ratio ischemic/non ischemic limb day 28: p-SN 0.78±0.04 vs. p-ctr 0.64±0.02; n=10; P<0.05). Interestingly, SN didn’t induce recruitment of endothelial progenitor cells to ischemic muscle in Apo E -/- mice (% lin - sca + flk + c-kit + cells: p-SN 1.72±0.3 vs. p-ctr 1.65±0.3, n=5, n.s.) In the MI-model cardiac parameters were significantly improved by SN-therapy (ejection fraction % 49.2±4.3 vs. 34.1±2.8, P<0.01; left ventricular end diastolic diameter mm 3.2±0.2 vs. 3.8±0.3, P<0.05; n=13). Aortic plaque area wasn’t affected by SN (Sudan IV staining % plaque area: p-SN 15.6±0.8 vs. p-ctr 15.2±2, n=5, n.s.) Conclusion: SN-therapy induces angiogenesis in-vitro and in-vivo without affecting vasculogenesis or atherosclerosis in HC and therefore represents a promising therapeutic strategy to reduce tissue ischemia in atherosclerotic diseases.