Bone Marrow Adipogenesis in Osteoporosis

Bone marrow adipogenesis is a postnatal event during bone and marrow development. In the adult bone, marrow adipocytes occupy the largest space of the marrow cavity, and serve as a source of energy, autocrine and paracrine factors. Marrow adipocyte share a common multipotential mesenchymal stem cell with other marrow stomal lineages, and functional overlap exists among them. In the marrow stroma microenvironment, adipogenesis is closely associated with osteogenesis, hematopoiesis and osteoclastogenesis. With ageing, increased marrow adipocytes accompany with decreased trabecular bone volume. Marrow adipogenesis may be an important complication of osteoporosis. Many regulators including hormones, growth factors, proinflammatory cytokines and their receptors such as nuclear hormone receptors, trans-memberane kinase receptors and G-protein coupled receptors are involved in the signaling pathway of adipogenesis, and may present potential molecular targets for the manipulation of adipocyte differentiation. Marrow adipocyte may be considered as an important target cell for the therapeutic intervention in osteoporosis. The inhibition of marrow adipogenesis and concomitant enhancement in osteogenesis may provide a potential approach to increase bone formation and therefore provide more efficacious prevention or treatment of osteoporosis.