Danhong injection (DHI) is a Chinese drug used for relieving cardiovascular diseases. This study aimed to identify the effect and mechanism of action of DHI on post-infarct angiogenesis, especially the epigenetic regulation of angiogenesis.

A myocardial infarction (MI) mouse model was induced by ligating the left anterior descending coronary artery. A 4-week daily treatment with or without DHI via intraperitoneal injection was started immediately following MI. The changes in cardiac function, pathology, and angiogenesis following MI were measured by echocardiography and immunostaining. Matrigel tube formation and scratch wound assays were used to evaluate the effect of DHI on the proliferation and migration of hypoxic human umbilical vein endothelial cells (HUVECs). The expression of miR-126, Spred-1, and angiogenesis-related mRNAs was measured by quantitative real-time polymerase chain reaction (qRT-PCR). The expression of related proteins and the phosphorylated levels of extracellular signal–regulated kinase (ERK) and protein kinase B were detected by Western blot analysis. The loss-of-function study was performed using antagomir-126.

The DHI-treated mice had significantly reduced infarct area, improved ejection fraction, and increased capillary density 4 weeks after MI. Also, DHI promoted the proliferation and migration of hypoxic HUVECs. The qRT-PCR and Western blot analysis revealed that DHI intervention upregulated miR-126, suppressed Spred-1 expression, and activated the ERK pathway, but not the Akt pathway. The loss-of-function study showed the blockade of the pro-angiogenic effect of DHI by antagomir-126 involving the ERK/vascular endothelial growth factor (VEGF) pathway.

DHI enhanced post-infarct angiogenesis after MI by activating the miR-126/ERK/VEGF pathway.