Transforming growth factor-beta expression in repairing dog alveolar bone defect during synergetic transplantation of peripheral blood stem cells and tissue engineered bone / 中国组织工程研究

ABSTRACT

BACKGROUND: The peripheral blood stem cell is a multi-differentiation precursor cell, and it can differentiate into osteoblasts. Tissue engineered bone, which is regarded as a vector of cell transplantation, has good compatibility with receptor tissue and seed cells. Transforming growth factor-β (TGF-β) is an important regulatory factor for repairing bone injury. Additionally, TGF-β can induce peripheral blood stem cells to differentiate and proliferate into osteoblasts.OBJECTIVE: To study TGF-β expression in repairing alveolar bone during synergetic transplantation of peripheral blood stem cells and tissue engineered bone. DESIGN: Observational study.SETTING: Stomatology Hospital of Xi'an Jiaotong University.MATERIALS This study was performed at the Stomatology Hospital of Xi'an Jiaotong University from 2003 to 2006. Experimental animals were provided by the Animal Experimental Center, Medical College of Xi'an Jiaotong University (original Xi'an Medical University). All animals were intramuscularly induced with ketamine, intramuscularly anesthetized with sumianxin, and then sacrificed for surgery. The experiment was approved by the local ethics committee.METHODS: Peripheral blood stem cells were extracted from dog and prepared as a cell suspension. Iliac bone was obtained from healthy pig to prepare decalcifying-deproteinic tissue engineered bone. The tissue engineered bone was then dipped into peripheral blood stem cell suspension. Ten healthy hybrid dogs were randomly divided into an experimental group and a control group, with 5 dogs in each group. An incision was made from left to right along the canine teeth of the lower mandible, along the lip, lateral to the gingival sulcus, to the alveolar crest, and then along the bilateral vestibular groove to form a trapezoid segment. Subsequently, the segment was turned downward to expose the bone lamella lateral to the lip. In addition, a bone defect region of 2 cm × 2 cm × 1 cm was drilled between the lateral incisor of lower mandible using a turbine drill. Peripheral blood stem cell-tissue engineered bone was implanted in the experimental group but tissue engineered bone only was implanted in the control group. At 2, 3, 4, 8 and 12 weeks after surgery, during the differentiation and proliferation of peripheral blood stem cell into osteoblasts, TGF-β expression was measured using immunohistochemistry.MAIN OUTCOME MEASURES: ① Morphological changes of peripheral blood stem cells differentiating into osteoblasts and structural function of organoid were observed under optical microscopy and by transmission electron microscopy. ② TGF-β expression was measured using immunohistochemistry during the differentiation and proliferation of peripheral blood stem cells into osteoblasts.RESULTS: Two weeks after peripheral blood stem cell-tissue engineered bone transplantation in the experimental group, TGF-β expression was mildly positive at the fringe of the bone defect. Four to eight weeks after the transplantation, high numbers of osteoblasts, fibroblasts and collagenous fibers were found at the center of the bone defect region, and TGF-β expression was strongly positive. The bone defect was completely repaired after 12 weeks. In the control group, 8-12 weeks after tissue engineered bone transplantation, TGF-β expression was mildly positive only at the fringe of the bone defect. CONCLUSION: During dog alveolar bone defect repair, TGF-β can induce peripheral blood stem cells, in combination with tissue engineered bone, to differentiate and to proliferate into osteoblasts.