Experimental studies regarding injectable chitosan/β-TCP/rhBMP-2 composite in repairing rabbit mandible defects / 中国组织工程研究

ABSTRACT

BACKGROUND: Traditional solid bone can not receive satisfied effects in repairing irregular bone defects in oral maxillofacial surgery due to uneven distribution of cells and growth factors. Therefore, it is a research direction to prepare injectable tissue engineering bone.OBJECTIVE: To explore the effects of chitosan/β-tricalcium phosphate/recombinant human bone morphogenetic protein-2(CS/β-TCP/rhBMP-2) composite on mandibular defect repair.DESIGN, TIME AND SETTING: A randomized controlled animal experiment. The experiment was performed atthe animal laboratory, Medical College of Jinnan University from May 2008 to March 2009.MATERIALS The injectable tissue engineering bone was prepared by using complex of liquid CS and solid β-TCP as scaffold materials, and combined with freeze-dried rhBMP-2.METHODS: Twenty-four New Zealand white rabbits were prepared for double sides mandibular defect models, and randomized into 4 groups ①CS/p-TCP/rhBMP-2 group 1 mL CS/β-TCP/rhBMP-2 complex was injected into the defects.②CS/β-TCP group0.5 mL CS/β-TCP complex was injected into defects. ③Autograft bone group repairing the defects with sclerotin of the iliac crest.④Blank control group no implantation. MAIN OUTCOME MEASURES: At weeks 2, 4 and 8 after surgery, the material degradation and new bone formation were evaluated with, haematoxylin-eosin staining, and electron microscope; the bone mineral density was detected by dual energy X-ray absorptiometry (DXA) to determine bone formation rate and quality.RESULTS: ①Gross observation demonstrated that the size and thickness of osteotylus in CS/β-TCP/rhBMP-2 group was equivalent with the autograft group, which were greater than that of the other groups.②Histologicalobservation demonstrated that there were more bone matrixes in the CS/β-TCP/rhBMP-2 group and autograft group than that in the CS/β-TCP group and blank control group at each time points. ③Scanning electron microscope image suggested that at 8 weeks after operation, the bone bed and the materials in CS/β-TCP/rhBMP-2 group were connected with bone, and the gap was diminished. The degradation of the materials was so obvious that the complete structure of materials could not be found. ⑤DXA detection appealed that the bone density of each group was gradually increased with time prolonged. The quantities of bone density in CS/β-TCP/rhBMP-2 group in weeks 2, 4 and 8 were significantly higher than CS/β-TCP group and blankcontrol group (P < 0.05).CONCLUSION: ①CS/β-TCP/rhBMP-2 has good biocompatibility, degradability and the capacity of bone guidance and bone induction. ②CS/β-TCP can be served as a promising carrier for BMP-2, which is a potential degradable biological material for repairing bone defects.