Myocardial infarction (MI) remains a leading cause of morbidity and mortality worldwide. Endothelial progenitor cell (EPC)-derived exosomes have been found to be effective in alleviating MI, while the detailed mechanisms remain unclear. The present study aimed to determine the protective effects of EPC-derived exosomal miR-1246 and miR-1290 on MI-induced injury and to explore the underlying molecular mechanisms. The exosomes were extracted from EPCs; gene expression levels were determined by quantitative real-time PCR, and protein expression levels were determined by western blot and immunofluorescence staining, respectively. The angiogenesis and proliferation of human cardiac fibroblasts (HCFs) were determined by tube formation assay and immunofluorescence staining of PKH67, respectively. Luciferase reporter, CHIP, and EMSA assays determined the interaction between miR-1246/1290 and the targeted genes (EFL5 and SP1). The protective effects of miR-1246/1290 on MI were evaluated in a rat model of MI. EPC-derived exosomes significantly upregulated miR-1246 and miR-1290 expression and promoted phenotypic changes of fibroblasts to endothelial cells, angiogenesis, and proliferation in HCFs. Exosomes from EPCs with miR-1246 or miR-1290 mimics transfection promoted phenotypic changes of fibroblasts to endothelial cells and angiogenesis in HCFs, while exosomes from EPCs with miR-1246 or miR-1290 knockdown showed opposite effects in HCFs. Mechanistically, miR-1246 and miR-1290 from EPC-derived exosomes induced upregulation of ELF5 and SP1, respectively, by targeting the promoter regions of corresponding genes. Overexpression of both ELF5 and SP1 enhanced phenotypic changes of fibroblasts to endothelial cells and angiogenesis in HCFs pretreated with exosomes from EPCs with miR-1246 or miR-1290 mimics transfection, while knockdown of both EFL5 and SP1 exerted the opposite effects in HCFs. Both ELF5 and SP1 can bind to the promoter of CD31, leading to the upregulation of CD31 in HCFs. Furthermore, in vivo animal studies showed that exosomes from EPCs with miR-1246 or miR-1290 overexpression attenuated the MI-induced cardiac injury in the rats and caused an increase in ELF5, SP1, and CD31 expression, respectively, but suppressed α-SMA expression in the cardiac tissues. In conclusion, our study revealed that miR-1246 and miR-1290 in EPC-derived exosomes enhanced in vitro and in vivo angiogenesis in MI, and these improvements may be associated with amelioration of cardiac injury and cardiac fibrosis after MI.

The present study aimed to prepare a kind of controlled-releasing insulin-like growth factor 1 (IGF-1)/spider silk protein nanofibrous membrane using a electrostatic spinning method and evaluated its effect on the cell viability of endothelial progenitor cells (EPCs). Recombinant spidroin named as GMCDRSSP-IgF-1 was electro-spun into nanofibrous membrane which can be degraded by protease and be capable of sustained-release of IGF-1. The membrane can be degraded after being treated with thrombin. The release assay results showed that IGF-1 concentration could be maintained at 20 ng/ml for a long time with treatment of Tobacco Etch Virus (TEV) protease. The viability of EPCs on GMCDRSSP-IgF-1 nanofibrous membrane was significantly increased with the presence of TEV protease. The controlled and sustained release of IGF-1 from the nanofibrous membrane could promote the adhesion and viability of EPCs. In summary, the nanofibrous membrane that exhibits controlled degradation and sustained release of IGF-1 was prepared with electrostatic spinning from genetically modified recombinant spider silk protein. The nanofibrous membrane exhibited good blood compatibility and cytocompatibility. With the presence of TEV protease, the sustained-release of IGF-1 significantly promoted the adhesion and viability of EPCs. The new nanofibrous membrane can be potentially used as a scaffold for EPCs culture in vitro and future in vivo studies.

Acute myocardial infarction (AMI) is a fatal cardiovascular disease with a high mortality rate. The discovery of effective biomarkers is crucial for the diagnosis and treatment of AMI. In the present study, miRNA sequencing and reverse transcription-quantitative polymerase chain reaction techniques revealed that the expression of exosome derived miR-152-5p was significantly downregulated in patients with AMI compared with healthy controls. A series of functional validation experiments were then performed using H9c2 cardiomyocytes. Following transfection of the cardiomyocytes using an miR-152-5p inhibitor, immunofluorescence staining of a-smooth muscle actin revealed a marked increase in fibrosis. Western blotting revealed that the expression levels of the apoptotic protein Bax, TNF-α and collagen-associated proteins were significantly increased, whereas those of the apoptosis-inhibiting factor Bcl-2 and vascular endothelial growth factor A were significantly decreased. Furthermore, the binding of Rho GTPase-activating protein 6 (ARHGAP6) to miR-152-5p was predicted using an online database and verified using a dual-luciferase reporter gene assay. The transfection of cardiomyocytes with miR-152-5p mimics was found to inhibit the activation of ARHGAP6 and Rho-associated coiled-coil containing kinase 2 (ROCK2). These results suggest that miR-152-5p targets ARHGAP6 through the ROCK signaling pathway to inhibit AMI, which implies that miR-152-5p may be a diagnostic indicator and potential target for treatment of myocardial infarction.