| Currently, it is difficult for orthopedic surgeons to treat larger bone defects caused by trauma, tumor resection, limb length discrepancies, short figure, and other diseases. At present , reconstruction of these skeletal deficits is often achieved by autogenous bone grafting. Although this technique is effective at healing small defects, moreover, grafting bone will be reabsorbed and necrose in the future. Artificial graft is limited by the defect sites. Therefore, orthopedists focus on how to stimulate bone formation. The technique of distraction osteogenesis (DO) requires diaphysis or metaphsis osteotomy and gradually distraction of the two bone segments, so that it can stimulate the bone formation. However, long period external fixation induce all kinds of complications such as: pin tract infection, ankylosis, muscle atrophy, and so on. We must solve the problems as soon as possible, 1. how to enhance distraction bone healing; 2. decrease the external fixation period, ultimately to prevent the complications. For these reasons we carried out the following studies. 1 Rat Model for Limb LengtheningObjective:Rat models for limb lengthening had been made to study osteogenesis mechanism induced by mechanical distraction using modern immunological andmolecularbiological techniques in the near future. Methods:Ring fixators were applied to the lower legs of 12 adult male rats. An osteotomy was made in the diaphysis of the tibia , and 5 days after the operation the bone fragments were distracted by 0. 25mm twice a day for 12 days. Radiographs were taken each week and the animals were killed at various stages to allow histological examination. Results:All animals were survived the operative procedures and distractive healing stages in good condition. No adverse effects resulting from the distraction procedure were detected. One animal was written off, because distal fracture of tibia was resulted from inserting k-wire uncarefully. Temporal superficial pin-tract infectious developed in the postoperative period in two animals, but did not influence the distraction and resolved without the use of antibiotics. Post operative edema of five rats were observed, but all resolved without treatment. The proximal and distal fragments of osteotomy were retented in a good position by X-ray detected. Cone Iution: Rats are better than other animals in studying on mechanism of distraction osteogenisis in cellular and molecular levels. 2 BFGF, IGF affect the proliferation and differentiation in vitro culture of bone mesenchymal stem cellsObjective To study the effect of basic fibroblast growth factor (bFGF) and insulin-like growth factor (IGF) on the proliferation and differentiation in vitro culture of bone mesenchymal stem cells (BMSc). Methods When the 3~6 months old male Sprague~Dawleg rat was killed, the marrow plugs obtained from bilateral femora and tibiae were cultivated in vitro. The media were divided into four groups according totheir containing different cell factors. I bFGF group; II IGF group ; III bFGF, IGF group ; IV control group (dexamethasone, P -glycersphosphoric acid, vitamin C, penicillin, streptomycin were added in all of groups). We observed the growth characteristics of BMSc under the microscope. We drew the curve of cell growth by the relative data from MTT method, detected the rate of ALP+by the improved Gomori' s method. Results At the beginning two days of culture, all of groups had no difference in cell quantity. The cell quantities of three groups with factors (bFGF, IGF, bFGF and IGF) were more than control group' s respectively, however, bFGF and IGF group were most in all groups. The groups including cell factors expressed rate of ALP+ more than control group, moreover, the bFGF and IGF group which expressed the rate of ALP+ were the most in all groups. Conclusion BFGF, IGF can enhance the proliferation of BMSc and differentiation into osteoblast, moreover, the effect of bFGF and IGF which are added to media at the same time is better than the effect of bFGF, IGF added respe...
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