The effects of EC-secreted paracrine factors on osteogenesis and osteoclastogenesis
In bone tissue, PDGF can recruit pericytes/MSCs, promote their growth, and inhibit their osteogenesis, and antagonize VEGF. BMP2 can promote osteogenesis, antagonize MGP, and Noggin. Besides, BMP2 can attract monocytes to adhere to ECs by antagonizing Noggin. VEGF can induce osteoclasts to migrate and affect osteoblastic differentiation. Furthermore, RANKL can induce osteoclastic differentiation by antagonizing OPG. As for inflammatory cytokines, CCLs and CXCLs can induce monocytes to migrate into bone tissue and differentiate into osteoclasts. MMPs can promote osteoclastic differentiation. Meanwhile, BMP2, VEGF, and CCL2 can prevent osteocyte apoptosis.