Effects of transforming growth factors on bone cells.

Bone formation results from the anabolic and catabolic functions of osteoblasts and osteoclasts within bone. The activities of these cell populations are controlled by complex interacting effects generated by local (bone-derived) and systemic (hormone) growth regulators. One of the more abundant growth regulators produced by bone cells and associated with bone matrix is transforming growth factor beta (TGF-beta). Recent studies indicate that TGF-beta controls the abundance and the biochemical function of osteoblasts and osteoclasts. Also, both TGF-beta production by bone cells, and its effects on bone cell activity, can be influenced by other local growth factors and osteotropic hormones.