Growth factor modulation of the formation of a molded vascularized bone graft in vivo

Peptide growth factors are potent regulators of osteoblast differentiation, proliferation, and maturation. Two of these growth factors, transforming growth factor beta (TGF-beta) and basic fibroblast growth factor (bFGF), were used in an attempt to stimulate osteoneogenesis and angiogenesis in a molded vascularized bone graft in the rat. Custom chambers containing cancellous autograft bone and agarose beads and incubated with TGF-beta, bFGF, or a control solution, were closed around the femoral artery/vein pedicle for 2-4 weeks. Control grafts were completely necrotic and without mechanical integrity. TGF-beta grafts demonstrated active osteogenesis around necrotic bone, osteoclastic activity, and limited angiogenesis. Basic FGF grafts demonstrated substantial angiogenesis with limited osteoblastic activity. This study suggests that TGF-beta and bFGF stimulate populations of cells in the formation of a molded vascularized bone graft. TGF-beta induces the proliferation and/or activity of osteoblastic cells, while bFGF stimulates cells involved in angiogenesis. Despite these findings, an insoluble demineralized matrix component may be required for complete transformation and graft consolidation.