| It is a new way to repair bone defect caused by bone tumor, wound and other diseases with tissue-engineered bone and anticipated to provide potent alternatives to free autogenous bone grafts. In this study , we provided tissue-engineered bone, which was manufactured by useing the compound materials of bone matrix gelatin(BMG) particles impregnated with polymethyl methacrylate (PMMA) bone cement(BC) as the support material, then combined with bovine bone morphogenetic protein (bBMP). After, we repaired the New Zealand rabbits' radius segmental bone defect using the tissue-engineered bone and discussed possibility of using the tissue-engineered bone as bone graft material. Firstly, we extracted bBMP from cortical bone of calfs, which were only one year old, referring to Urist's methods. Then, the bBMPs were analysed by SDS polyacrylamide gel eletrophoresis and their activity of osteogenesis were evalued by muscle pouch test. Secondly, we provided tree kinds of the support materials which repectively consisted of 40%, 50%, 60% BMG particles, then analysed the constructive and biomechanical properties of the different quality ratio materials impregnated BMG particles with bone cement by scanning electron microscope(SEM) and Instron mechanics testing-machine. At the same time, the data were compared with that of hydroxyapatite and adult female fresh femur. Finally, we observed the osteogenesis and way of new bone fonnatin in repairing bone defect model using the tissue-engineered bone consist of 50% BMG particles with gross. X-ray, single photo emission computed tomography(SPECT). histomorphological and scanning electronic microscope at different periods after operation in contrast to using autologous bone. The results of the experiment prove the following facts: 1, The infiltration of inflamed cells was not seen in the muscle pouch test, and also no obvious immune rejection was observed. Mesenchymal cells began toproliferate and differentiate into cartilage cells at one week post-implantation, afterward. the cartilage is resorbed and replaced by new bone and marrow at the end of a further two-week period, finally, the original implant is completely replaced by new bone tissue which has normal Haversian system at four-week after operation. SDS polyacrylamide gel eletrophoresis of bBMP procured according to improved Urist's method showed some Coomassie Billiant blue-staining components which represented 30KD, 18KD and other osteogenic protein components. The bBMPs have a property of dosage-dependence, so it is better to use them by being compounded with delivery system. 2, The BMG particles were connectd with EC by the multi-polar mode in the compounds; There were many irregular 100-400nm gaps which were connected each other in the compounds. The BC acted as skeleton and connective intermediary. As the BMG particles increased, the number of gaps increased. The ultimate compressive strengths were (71.1 ?.0) MPa for Omg/g BMG, (46.9?.3) MPa for 400mg/g BMG, (39.8?.1) MPafor 500mg/g BMG, (32.2?.4) MPa for 600mg/g BMG respectively; The ultimate three-point bending strengths were (65.0 ?3.4) MPa for Omg/g BMG; (38.2 ?.0) MPa for 400mg/g BMG, (33.1 ?4.3 ) MPa for 500mg/g BMG, (25.3 ?4.6) MPa for 600mg/g BMG respectively. 3. There was no significant deference in the rate of healing between the tissue-engineered bone and the autologous bone. The tissue-engineered graft was similar to the fresh autologous bone graft in healing process and the way of new bone formation. Allogenic BMG particles impregnated with bone cement act as a good bBMP slow-releasing carriers, then the released BMPs which were contained in the BMG particles and bBMP compounded with the tissue-engineered affected on the mesenchymal cells from host slowly, so the mesenchymal cells differentiated into cartilage cells and osteoblasts continually, finally, the new bone induced by the BMP were formed in the pores of the tissue-engineered bone, at the same time, no immune rejection were observe in the whole process of new bone growth. In conclusi... |
PDF Full Text Request