Muscone improves coronary microvascular disease by promoting VEGF-mediated microvascular angiogenesis

To explore the impact of Shexiang Baoxin Pill (SXBXP, a traditional Chinese patent medicine, broadly applied for the treatment of cardiovascular diseases) on coronary microvascular disease (CMD) and investigate the role and underlying mechanisms of muscone, a key bioactive component of the pills, in the treatment.

A total of 16 ob/ob mice (8 weeks old) were randomly and equally divided into an ob/ob-SXBXP group and a ob/ob-Control group, receiving 10 mg/kg·d SXBXP or PBS via oral gavage, and another 8 wild-type mice with the same genetic background (WT group) were subjected as a negative control group. Cell model of CMD was established based on mouse coronary microvascular endothelial cells (MCMEC) under ischemia and hypoxic (HI) condition, and the cells were further treated with 20 μg/mL SXBXP (HI+SX) and 30 μmol/L muscone (HI+Muscone), respectively. Echocardiography was carried out for coronary flow reserve (CFR) and left ventricular function, and laser speckle imaging was applied to evaluate myocardial blood flow (MBF). Microvascular density in the heart was evaluated with CD31 immunofluorescence staining. The expression levels of vascular endothelial growth factor (VEGF) in cardiac microvascular endothelial cells of both mouse and cell models were detected by immunofluorescence staining and Western blot analysis. The proliferation and angiogenesis of MCMEC were observed by 5-ethynyl-2'-deoxyuridine staining and angiogenesis experiments.

In the ob/ob-Control group of mice, the levels of CFR, MBF, and cardiac microvascular density were significantly lower than those in the WT group (P<0.05), and these indicators were significantly improved in the ob/ob-SXBXP group when compared with the ob/ob-Control group (P<0.05), which indicates that SXBXP improves the CMD phenotype. The expression level of VEGF in cardiac microvascular endothelial cells was significantly lower in the ob/ob-Control mice than the WT mice (P<0.05), while the level in the ob/ob-SXBXP group was significantly higher than that in the ob/ob-Control group (P<0.05), illustrating that SXBXP may ameliorate CMD through VEGF-mediated microvascular angiogenesis. In vitro experiments further revealed that the VEGF expression level and the proliferation and angiogenesis abilities in MCMEC were significantly lower in the HI group than the cells under the normoxia control condition (P<0.05). Both SXBXP and muscone treatment resulted in enhanced expression of VEGF and improved proliferative and angiogenesis abilities of MCMEC (P<0.05). These results suggest that muscone could improve CMD by VEGF-mediated microvascular angiogenesis.

SXBXP can improve CMD. Muscone, as a key component of SXBXP, promotes microvascular angiogenesis by inducing the expression of VEGF, then enhances myocardial perfusion, and consequently alleviates CMD.