Shim, W. S., S. Y. Lim, S. Q. Li, Y. Gu, H. C. Ong, I. C. Song, S. C. Chuah and P. Wong. Structural stability of neoangiogenic intramyocardial microvessels supports functional recovery in chronic ischemic myocardium. J Mol Cell Cardiol. 2008.
We hypothesize that combining angiopoietin-1 (ANG-1) or ANG-2 with vascular endothelial growth factor (VEGF) improves myocardial perfusion and contractile function by modulating vascular adaptation of neoangiogenic microvessels in a chronic ischemic swine model. Four weeks after occlusion of the left circumflex coronary artery (LCx), animals were injected with AdVEGF(165) (n=6), AdVEGF(165)+AdANG-1 (n=6), AdVEGF(165)+AdANG-2 (n=6) or control vector (n=5) into the left ventricular posterolateral wall. Regional perfusion by fluorescent microspheres and segmental myocardial tissue velocity by tissue Doppler imaging (TDI) were assessed at baseline, 4 weeks post occlusion and 4 weeks post therapy. Despite similar vascular growth following VEGF+ANG-1 and VEGF+ANG-2 treatments, transmural myocardial contractility improved only when VEGF was paired with ANG-1. In contrast, regional systolic function deteriorated uniformly across subepicardial, mid-myocardial and subendocardial segments in VEGF and VEGF+ANG-2 treated groups. Contractile improvement was associated with enhanced vascular stability through augmented arteriole formation, tight structural integration between VE-cadherin and beta-catenin at endothelial junctions and improved cross-talk between endothelium and myocardium. Structural stability of developing intramyocardial microvessels contributes to systolic function during ischemic neovascularization. Coordinated regulation of angiogenic revascularization that supports vascular stability is a key aspect in improving therapeutic outcomes in ischemic myocardium.