Skeletal effects of systemic treatment with basic fibroblast growth factor.

Systemic treatment of intact and ovariectomized rats with basic fibroblast growth factor (bFGF) has strong bone anabolic effects. These effects include marked increases in osteoblast number and activity along cancellous and endocortical bone surfaces, which result in accumulation of osteoid and augmentation of cancellous and cortical bone mass after only short-term treatment with bFGF. Osteoclast surface is markedly decreased in bFGF-treated rats, but this finding may be secondary to the extensive osteoid surface in these animals. Some undesirable skeletal effects of the growth factor include impaired bone mineralization and formation of structurally inferior woven bone. The lack of a bone anabolic response to bFGF at skeletal sites with fatty marrow and along the periosteal surface of cortical bone is also disappointing. Despite these disadvantages, bFGF stimulates cancellous bone formation to such a great extent that it may eventually be considered for use in patients with severe osteoporosis who are unresponsive to conventional therapies, provided that local delivery of the growth factor to bone can be achieved to avoid systemic side effects.