| Objective: To discuss the feasibility of repairing rabbit radial defects through tissue-engineering bone with bone marrow stem cells(BMSCs) culture in vitro and make compsite grafts with bio-derived bone(BDB).Methods: BMSCs were cocultured with BDB in vitro, and the 15mm length of midshaft diaphyseal bone were removed at two radii in 25 New Zealand rabbits. They were divided into experimental group, control group and bank group. The compsite grafts were implanted into the right side defects by open operation as experimental group, the left side defects with bio-derived bone as control group in 20 rabbits, and the both sides defects were not filled with any materials as the blank group in 5 rabbits. The repair capability was assessed physically, radiographic examination, histologic at 2, 4, 8 and 12 weeks after operation in 3 groups.Results: the radiographic results indicate: a few bony callus was observed in the gap of bone defects interfaces in the experimental group, while there were not marked change in the control group at the end of the 2th weeks. In the 4th weeks we can observed many bony callus in the experimental groups. At the same time in the control group few callus appeared in gap of the bone defects interfaces. In the 8th weeks, new bone density increased and partially cortical bone bridged in the experimental group. In the control group, there were fuzzy callus growth and callus moved in implanted grafts. In the 12th weeks, new bone remodeled well and cortical bone completely bridged and new marrow cavity regenerated in the experimental group. In the control group, new bone remodeled weakly and partially marrow cavity appeared . In the blank group, bone defects could not be repaired and formed bone non-union after postoperation 12 weeks.Histological indicate : there were small amounts of fibrous connective tissue, blood vessel and cell aggregation in ventage of the scaffold in the experimental group at the 2th weeks. While in the control group, in which only found small amounts of fibrous and lymphocytic. In the 4th weeks, the bio-derived bone was partially absorbed in the experimental group and was rarely absorbed in the control group. In the ventage of the implant has some osteoids. The implant was perfectly absorbed and bone defects were partially repaired in the experimental group in the 8th weeks. Hower, in the control group, the two ends of the implant only observed few new bones. In the 12th weeks, the bone defects completely repaired in the experimental group, and the proximal and the distal of the implant were surrounded and bridged the defects by new bone in the control group. In the blank group, the bone defects were finally filled with fibrous tissue.Roentgenographically, the bone defects that had been treated with grafts exhibited new bone formation increased with time. But the result of experimental group was apparently superior to that of the control group's at 2,4,8,12 week after operation(p<0.05). The rate and quality of new bone formation were siginificationtly different in the experimental and the control group on histologic analysis(p<0.05). In the defects in blank group, no formation of new bone were found afer operation and were finally filled with fibrous tissue.Conclusion: BMSCs /BDB may be compounded and cultured in vitro, by scanning electro-microscopic observation and animal experimental. BDB may be used as an alternative carrier for seeded cells. The study demonstrate that tissue-engineering bone quickly promote the new bone formation on radial defects, and its repair capability is better than that of BDB alone.
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