Effects of basic fibroblast growth factor on bone allografts. A study using bone harvest chambers in rabbits

Bone grafts which have been supplemented with a growth factor might incorporate faster. In this study we investigated the effect of basic fibroblast growth factor (bFGF). Titanium bone harvest chambers were implanted bilaterally in the proximal tibia of rabbits. These chambers were pierced by a transverse bone ingrowth canal from which 1 x 1 x 5 mm cancellous bone rods were repeatedly harvested at 5 weeks intervals. The bone rods to be used as allografts were frozen as ordinary bank bone, and then lipid-extracted. This treatment yields a graft which elicits less of an immunologic response than allografts which are only frozen and thawed. Before implantation, the bone rods were soaked in a cellulose gel containing 0.5 microgram/ml recombinant human bFGF or gel without bFGF as a control. The grafts were then implanted pair wise (bFGF and control) in the chambers of recipient rabbits. These chambers were harvested after 2 weeks. Evaluation was made by Tc-MDP scintimetry, histomorphometry and histology. Upon histology new living tissue had filled the grafted chambers entirely and partly replaced the graft. bFGF induced an increased amount of pre-osteoblastic tissue in the bFGF-treated grafts (p < 0.02), but there was no difference in the amount of osteoid or new bone.