Improving the efficacy of therapeutic angiogenesis by UTMD-mediated Ang-1 gene delivery to the infarcted myocardium

This study aimed to verify the feasibility and efficacy of ultrasound-targeted microbubble destruction (UTMD)-mediated angiopoietin-1 (Ang-1) gene delivery into the infarcted myocardium. Microbubbles carrying anti-intercellular adhesion molecule-1 (ICAM-1) antibody were prepared and identified. The microbubbles carrying anti-ICAM-1 antibody selectively adhered to the interleukin (IL)-1β-stimulated ECV304 cells and to the ischemic vascular endothelium, and the infarct area was examined to evaluate the targeting ability of ICAM-1 microbubbles in vitro and in vivo. The intravenous administration of the Ang-1 gene was carried out by UTMD in rabbits with acute myocardial infarction (AMI). The rabbits were divided into the control (no treatment), non-targeted microbubble destruction (non-TMB) and the ICAM-1 TMB (TMB) group. Gene delivery by direct intramyocardial injection (IMI) served as a reference. Two weeks later, regional myocardial perfusion and cardiac function were evaluated by echocardiography, and Ang-1 gene-mediated angiogenesis was assessed histologically and biochemically. The results revealed that the ICAM-1-targeted microbubbles selectively adhered to the IL-1β-stimulated ECV304 cells in vitro and to the ischemic vascular endothelium in the infarct area of the rabbits with AMI. Two weeks after the delivery of the Ang-1 gene, compared with the non-TMB group, left ventricular function and myocardial perfusion at the infarct area had improved in the TMB and IMI group (p<0.01). Ang-1 gene expression was detectable in the non-TMB, TMB and IMI group, while its expression was higher in the latter 2 groups (all p<0.01). The microvascular density (MVD) of the infarct area in the non-TMB, TMB and IMI group was 65.6±4.4, 96.7±2.1 and 100.7±3.6, respectively (p<0.01). The findings of our study indicate that UTMD-mediated gene delivery may be used to successfully deliver the Ang-1 gene to the infarcted myocardium, thus improving the efficacy of therapeutic angiogenesis. This may provide a novel strategy for future gene therapy.