FIGURE 1.

Schematic diagram of the role of exosomes in bone growth: Exosomes derived from BMSCs, UCMSCs, ADSCs, EPCs, OBs, M2s, Ocy, ECs, VSMCs, and MBs can promote bone formation, while exosomes derived from BMSCs, UCMSCs, ADSCs, OCs, M2s, ECs, and VPs can inhibit bone resorption, leading to a state where bone formation exceeds bone resorption, thereby resulting in positive bone growth. It is noteworthy that both OB-Exos and OC-Exos have negative feedback mechanisms; at certain stages, mature OB-Exos can inhibit osteoblast differentiation to prevent excessive bone formation, while mature OC-Exos can conversely promote bone formation, thereby achieving the dynamic transition between bone formation and bone resorption phases in the bone remodeling process. (Abbreviation: BMSC, Bone marrow mesenchymal stem cell; UCMSC, umbilical cord mesenchymal stem cell; ADSC, adipose-derived stem cell; EPC, endothelial progenitor cell; OB, Osteoblast; M2, M2 macrophages; Ocy, Osteocyte; EC, vascular endothelial cell; VSMC, vascular smooth muscle cell; MB, myoblasts; OC, Osteoclast; VP, vascular pericytes).