M1 macrophage-derived exosomes transfer miR-222 to induce bone marrow mesenchymal stem cell apoptosis.

In the myocardial infarction microenvironment, the effect of macrophages on the function of bone marrow mesenchymal stem cells (BMSCs) is unclear. In this study, we investigated the role of hypoxia/serum deprivation (H/SD)-induced M1-type macrophage-derived exosomes on BMSC viability, migration, and apoptosis. We found that H/SD reduced BMSC viability and migration, increased BMSC apoptosis, and induced macrophage polarization toward the M1 phenotype. BMSCs were cultured by the supernatant of H/SD-induced THP-1 cells (M1-type macrophages) with or without exosome inhibitor treatment. The results show that BMSC apoptosis is increased in the H/SD-induced THP-1 cell supernatant group and is decreased by GM4869 treatment, indicating that M1-type macrophages induce BMSC apoptosis through exosomes. In addition, we confirm that miR-222 plays an important role in promoting BMSC apoptosis by targeting B-cell lymphoma (Bcl)-2. M1-type macrophage-derived exosomes significantly decrease BMSC viability and migration and increase BMSC apoptosis, and these effects are partly abolished by a miR-222 inhibitor. Our findings suggest that under H/SD conditions, exosomes derived from M1-type macrophages can induce BMSC apoptosis by delivering miR-222 to BMSCs.