Objective: To study the effect of transforming growth factor β/bone morphogenetic protein (TGFβ/BMP) composite on healing of large segmental bone defects and the interaction between TGF-β and BMP.Methods: A 1. 5-centimeter segmental defect was created in the mid-upper part of the radial shaft of adultrabbit. The defects were filled with implant of TGF-β/carrier, BMP/carrier and TGF-a/BMP/carrier, respectively. Purified bovine TGF-β 120 μg and BMP 12 mg were used in the composite. The defects were examined radiographically and histologically at 4, 8. 12 and 16 weeks post-operation (PO). Results: In groupof TGF-β/carrier, the defect areas were bridged at 4 weeks PO, with material of uniform radiodensity. Conices of the cut ends were obscured by the new bone. By 16 weeks PO, the defects were bridged by uniformnew bone and the cut ends of cortex could not be seen in all groups. In group of BMP/carrier, the defectswere filled with more irregular woven callus in comparison with the other two groups. The TGF-β/BMP--implanted defect sites in animals killed at 16 weeks PO showed histologically new larnellar and woven bone,formed in continuity with the cut ends of the cortex. The medullar cavity was recanalized and contained marrow elements with normal appearance. ConClUsion: These data demonstrate the synergistic action betweenTGF-β and BMP in the process of bone healing, and the better effect of TGF-β/BMP composite than that ofsingle TGF-β or BMP on bone repair.
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