Objective: To study the expression and function of TGF-beta 1 in the monkey's mandibular distraction osteogenesis process.
Methods: Sixteen rhesus monkeys were used for unilateral and bilateral mandibular distraction osteogenesis. Mandibular osteotomy was done at the mandible angle. After 5 days of latency period, the distraction was initiated at the rate of 0.5 mm x 2/day, lasting totally 15 days. In different periods after distraction completed, the bone in the distraction gap was routinely treated for immunohistochemistry and histology study.
Results: In the early period after distraction, the positive stain of TGF-beta 1 granules distributed extensively in the fibrous and vessel bases in the distraction gap, and in the cytoplasm of osteoblasts and chondroblasts. During the consolidation period, the positive stain of TGF-beta 1 granules alleviated gradually, and mainly distributed in the area where collagen fibers were ossifying and osteoids were forming, especially in the platelet and in the cytoplasm of vessel endothelial cells and osteoblasts. Twelve weeks after distraction, positive stain of TGF-beta 1 could seldom be seen except in the marrow's fibrous and vessel bases.
Conclusions: TGF-beta 1 actively participates in the new bone forming process in the distraction gap. It may play an important role in stimulating and inducing proliferation and differentiation of primitive mesenchymal cells, and can enhance the proliferation of osteoblasts and vessel endothelial cells.