Astragalus membranaceus extract promotes angiogenesis by inducing VEGF, CD34 and eNOS expression in rats subjected to myocardial infarction

The aim of the study is to determine the angiogenesis effect of Astragalus membranaceus extract (AME) on myocardium of rats with MI in vivo and to study its possible mechanisms involved in vascular endothelial growth factors (VEGF), cluster of differentiation 34 (CD34) and endothelial nitric oxide synthase (eNOS). A Sprague-Dawley rat model of MI was established by ligation of the left anterior descending coronary artery. Forty rats were randomized into 5 groups: MI control group, 3 different doses of AME (10, 20, 40 mg·kg-1·d-1) groups, and the Sham-operated group, each group consisted of 8 rats. The MI control group and sham-operated group were fed 0.9% sodium chloride 20 ml·kg-1·d-1. The rats were sacrificed after treated 8 weeks, hematoxylin-eosin staining, Masson staining and electron microscopy scanning were used to observe the pathomorphological changes of the myocardial tissues and vessels structure in the ventriculus sinister of rats. Immunohistochemical staining and western blot were used to evaluate the expression of VEGF, CD34 and eNOS. Compared with the MI control group, the morphology and arrangement of cardiomyocytes and the integrity of endothelial cells were improved, the contents of collagen fibers in myocardial tissues were decreased and the number of the new formed microvessels were increased in the myocardial tissues of rats in the AME treated groups. The VEGF, CD34 and eNOS protein expression in the myocardial tissue of the rats treated with different doses of AME increased significantly (P < 0.01). AME can obviously improve the disorganized myocardial tissues and promote angiogenesis in the rats after MI, which was accompanied by significantly increased expression of VEGF, CD34 and eNOS protein.