Ameliorative Effects of Extracellular Vesicles Derived from Mesenchymal Stem Cells on Apoptosis and Differentiation of Osteoblasts Treated with CoCl 2 .

Severe osteoporotic fracture occurring in sites with inadequate blood supply can cause irreversible damage to cells, particularly osteoblasts, with current drug and surgical interventions exhibiting limitations for elderly individuals. As participants mediating intercellular communication, extracellular vesicles (EVs) are rarely reported to play functional roles in osteoblasts under hypoxia. Our study mainly investigated the effects of bone marrow mesenchymal stem cells-derived EVs (BMSCs-EVs) on apoptosis and differentiation of osteoblasts treated with CoCl 2 . Primary rat BMSCs and osteoblasts were extracted as required for the following experiments. Cell counting kit 8 assay was used to explore the concentration of CoCl 2 for treating osteoblasts, and we found that 100 μM CoCl 2 was appropriate to treat osteoblasts for 48 hours. The analysis of flow cytometer showed that CoCl 2 -treated osteoblasts apoptosis can be ameliorated when cocultured with BMSCs-EVs. Further findings revealed that reactive oxygen species (ROS) was related to CoCl 2 -induced apoptosis. In addition, our results demonstrated that EVs exerted an important role in increasing expression levels of ALP , BMP-2 , OCN , and OSTERIX under hypoxia. Similarly, the functional effects of BMSCs-EVs were observed on the osteoblasts mineralization. In summary, these findings provide insight that BMSCs-EVs might decrease the effect of CoCl 2 -induced apoptosis through inhibiting ROS, and promote osteogenic differentiation under hypoxia.