CCL2 and osteonecrosis: In recent years, the emerging field of osteoimmunology has elucidated the close relationship between inflammatory cytokines and osteonecrosis.[30,32,35] For instance, some studies have shown that TNFα inhibits osteogenesis and further damages bone tissue, while MCP-1 can induce monocyte/macrophage proliferation and promote osteoclast differentiation and activation.[36,37] Previous research has indicated that overexpression of CDCP1 in extracellular vesicles, in the presence of NF-κB ligand, facilitates osteoclastogenesis,[38] suggesting its involvement in the development of osteonecrosis.