Mandibular distraction osteogenesis enhanced by bone marrow mesenchymal stem cells in rats

Objective: This study was to observe the effects of bone marrow mesenchymal stem cell transplantation on new bone formation in a rat mandibular osteodistraction model. Material and methods: Autologous bone marrow stem cells were obtained from tibiae of 40 male rats. Two weeks after cell harvest, the rats underwent right mandibular distraction and were then randomly divided into two groups (group A = 20, group B = 20). After distraction was complete, the stem cells were injected into the distracted gaps in group A, while the rats in group B only received physiological saline. Twenty rats (10 from each group) were sacrificed on postoperative days 27 and 55, respectively. The distracted mandibles were harvested and processed for radiographic, histological and histomorphometric analysis. Results: The radiodensity of the distraction zone was higher in group A than in group B at both time points. Histologically callus was found in both groups but more bone was formed in group A. Histomorphometric analysis also demonstrated that both new bone volume and thickness of the new trabeculae were significantly greater in group A than in group B. Conclusion: The results of this study suggest that autologous bone marrow stem cell transplantation may be considered as a potential method to accelerate bone regeneration in the distraction gap, and enhance consolidation. (C) 2006 European Association for Cranio-Maxillofacial Surgery.