[Angiogenesis in chronic ischemic porcine myocardium after transfer of VEGF₁₆₅ and angiopoietin-1 mediated by recombinant adeno-associated viral vector].

OBJECTIVE

To study the effects of combination of angiopoietin-1 (ANG-1) and vascular endothelial growth factor₁₆₅ (VEGF₁₆₅) gene transfer mediated by recombinant adeno-associated viral vector on the neovascularization in chronic ischemic porcine myocardium.

METHODS

An ameroid constrictor was implanted around the left circumflex coronary artery (LCX) via endoscopy. Six weeks later, coronary angiography revealed that the myocardial ischemia was established by gradual occlusion of the left circumflex coronary artery (LCX). Sixteen swine with the total occlusion or partial stenosis (> 85 %) of the LCX were divided into 4 groups (4 in each group): group I, group II and group IV (control) received direct myocardium injection of rAAV₂ VEGF₁₆₅, rAAV₂ ANG-1 or PBS alone, respectively; group III received rAAV₂ VEGF₁₆₅ and rAAV₂ ANG-1. Selective coronary angiography and ultrasonography were performed perioperatively to evaluate the cardiac function and the formation of collateral circulation. The expression of VEGF₁₆₅ and ANG-1 proteins were assessed using ELISA or Western blot. The degree of angiogenesis was assessed by use of immunohistochemical analysis.

RESULT: Angiography showed that the occlusion of all LCX was completed or exceeded 95% 6 weeks after ameroid constrictor implantation, indicating the successful establishment of animal model. The expression levels of VEGF₁₆₅ in group I and III and ANG-1 in groups II and III began to increase at d7 after transfection and reached the peak at d14; then decreased gradually to the normal level after 3 months. The expression levels of VEGF₁₆₅ in group II and group IV or that of ANG-1 protein in group I and group IV had no markedly changes at different time after transfection. There were significant increase in capillary density and arteriole density and more side branch vessels formed in group III compared with other groups. Echocardiographic measurements showed that the left ventricular systolic function of animals in groups I, II and III increased significantly after gene transfection, especially in group III; but there was no changes in group IV.

CONCLUSION

Myocardial perfusion and the left ventricular systolic function are improved after rAAV₂ VEGF₁₆₅ or rAAV₂ ANG-1 transfection, which is associated with the angiogenesis in porcine model of chronic myocardial ischemia.