Exosomes derived from circBCRC-3-knockdown mesenchymal stem cells promoted macrophage polarization

Macrophages play an essential role in the myocardial ischemia-reperfusion injury (MIRI), and the macrophage shifting from M1 to M2 phenotypes might be a potential strategy for the treatment of MIRI. It has been reported that miR-182 plays an important role in MSC-Exo-associated macrophage polarization. As circBCRC-3 is a newly discovered circle RNA that worked as a sponge of miR-182, this research aimed to find if circBCRC-3 plays a role in MSC-Exo-associated macrophage polarization. Firstly, circBCRC-3 was identified by divergent primers in mesenchymal stem cells (MSCs). Secondly, the exosome of MSCs was isolated and identified by transmission electron microscopy (TEM), nanoparticle-tracking analysis, and western blotting analysis. The expression level of circBCRC-3 in MSCexos was detected by RT-PCR. Finally, the polarization of the RAW264.7 cell phenotype was analyzed by flow cytometry. Moreover, we first identified circBCRC-3 in MSCs. The results further confirmed that MSCexo could effectively shift the macrophage polarization state from M1 towards the M2 phenotype, which indicated its role in MIRI cure.