In vivo stimulation of bone formation by transforming growth factor-beta.

The effect of transforming growth factor-beta (TGF beta) on bone in vivo was examined. Twelve daily injections of 1 microgram TGF beta directly onto the periostea of parietal bones of neonatal rats stimulated the formation of periosteal woven bone. The thickness of the treated parietal bones increased at least 2-fold in a dose-dependent manner. This TGF beta effect was localized at the sites of injection, and no change was observed in contralateral parietal bones and tibiae. The body weight in these growing rats was not affected by TGF beta 1. TGF beta 2 had effects similar to those of TGF beta 1 on the parietal bones in vivo. These results reveal for the first time that TGF beta stimulates bone formation in vivo and indicate its anabolic role in local bone metabolism.