Angiopoietin-1 promotes functional neovascularization that relieves ischemia by improving regional reperfusion in a swine chronic myocardial ischemia model

Summary This study investigates the long-term angiogenic effects of ANG-1 and VEGF in a swine chronic myocardial ischemia model. Four-weeks after gradual occlusion of the left circumflex coronary artery by ameroid constrictor, animals were injected with recombinant adenoviral vectors carrying either human ANG-1 (n=9), human VEGF₁₆₅ (n=10) or empty vector (n=7) into the left ventricle free wall supplied by the constricted artery. Left ventricular perfusion in animals that received AdANG-1 (3.25±0.16 ml/min/g, p<0.05) recovered robustly 4 weeks after gene transfer while ischemia persisted in the AdVEGF (1.09±0.13 ml/min/g) and empty vector (1.20±0.03 ml/min/g) groups. Microvascular densities in the left ventricles of animals that received AdANG-1 (19.61±1.76/0.572 mm² myocardial tissue, p<0.05) and AdVEGF (18.17±1.43/0.572 mm² myocardial tissue, p<0.05) were significantly higher than animals that received empty vector (13.53±0.92/0.572 mm² myocardial tissue) 12 weeks after gene transfer. ANG-1, but not VEGF, contributed to enhanced regional perfusion by increasing arteriolar density (1.9±0.4/0.572 mm² myocardial tissue vs. 0.7±0.2/0.572 mm² myocardial tissue, p<0.05) of large-sized (50–100 μm) arterioles. These data demonstrate that gene transfer of ANG-1 and VEGF enhances angiogenesis, but ANG-1 promotes sustained improvement of ventricular perfusion that expedites recovery of ischemic myocardium via arteriogenesis.