Immunohistochemical Analysis of Reconstructed Sheep Mandibles: Transport Distraction Osteogenesis Versus Autogenous Bone Grafting

Abstract

Although many studies have been conducted that related to growth factor expression in mandibular distraction osteogenesis, to our knowledge, no study comparing the immunohistochemical outcomes of autologous bone grafting (ABG) and transport distraction osteogenesis has been conducted up to now. The aim of this study was to histologically and immunohistochemically analyze newly formed bone in the resected mandible reconstructed by transport distraction osteogenesis and iliac crest bone grafting in a sheep model. Mandibular discontinuity defects created in the jaws of sheep were reconstructed by distraction osteogenesis (n = 7) and bone grafting (n = 7) and allowed to heal for 3 mos. The animals were then sacrificed and their jaws resected and prepared for decalcification. Histological and immunohistochemical examinations of transforming growth factor-beta 1 (TGF-β1) and bone morphogenetic protein (BMP) -2, -4 were performed in the newly formed bone in the defect area. Positive staining for BMP-2, -4, and TGF-β was observed in the cells and matrix components. BMP is present in both processes, but the expression of BMP-2, -4, and TGF-β in the distraction regenerate is stronger when compared with bone graft healing. The only limitation of the present study was that it evaluated the role of BMP-2, -4, and TGF-β expressions in bone repair process at 3 mo postoperatively. Determination of growth factor expression at more than 1 time point would be ideal in elucidating the role of these factors during bone healing.