Cardioprotective Extracellular Vesicles Derived-Micrornas: Sorting Mechanisms and Functions

Extracellular vesicles (EVs) are nano-size membrane bound vesicles that are derived from the fusion of multivesicular endosomes with the plasma membranes. EVs have important roles in intercellular communication through the transfer of their unique cargoes including RNA, DNA and protein molecules to recipient cells. Mesenchymal stem cell (MSC)-derived EVs have been shown to reduce infarct size and reduce the progress of heart failure after cardiac ischemia/reperfusion (I/R) injury in animal models. Small non-coding RNAs such as microRNA (miRNA) have been indicated as one of the active components that mediate the beneficial effects of MSC-derived EVs. However, the selective packaging mechanisms of these EV-enriched miRNAs as well as their specific functions in recipient cardiomyocytes are still incompletely understood.Regarding the sorting mechanisms of miRNAs into MSC-derived EVs, we characterized the role of heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1) in controlling the distribution of the miRNA population to EVs. We showed that disruption of the gene encoding hnRNPA2B1 prevented much of the loading of miR-486-5p into MSC-derived EVs. Based on RNA immunoprecipitation, gel-shift and biotinylated RNA pull-down assays, we confirmed the interaction of miR-486-5p and hnRNPA2B1. Because miR-486-5p was the predominant miRNA in EVs and almost absent in producer cells, we focused on the function of miR-486-5p in cardioprotection against I/R injury. Using different in vitro and in vivo functional assays, we demonstrated that miR-486-5p is protective against I/R injury by inhibition of PDCD4-induced apoptosis in cardiomyocytes. The findings represented here indicated that hnRNPA2B1 interacts with miRNAs and mediates packing of miRNAs into MSC-derived EVs via a specific nucleotide motif in the miRNAs. One of the most highly EV-packaged miRNAs, miR-486-5p is cardioprotective in cardiomyocytes and in the heart