BMP2 and osteoporosis: BMSC-Exos transplantation plays a key role in the treatment of osteoporosis by promoting osteogenesis, which is attributed to the activation of bone morphogenetic protein-2-drosophila mothers against decapentaplegic protein1runt-related transcription factor-2 (BMP-2/Smad1/RUNX2) and hypoxia-inducible factor-1-vascular endothelial growth factor (HIF-1α/VEGF) signaling pathways (Zhang et al., 2020).