The Experiment Research On Repairing Bone Defects Using Recombinant Human Bone Morphogenetic Protein-2, Platelet-rich Fibrin And Autologous Bone Compositeding With Coralline Hydroxyapatite Respectively

Objective: The tibial metaphyseal of Beagles bone defects animal model was establishedand the following: four groups of bone transplantation materials were implanted into thedefect area respectively. They arecompound of recombinant human bone morphogeneticprotein-2(rhBMP-2), coralline hydroxyapatite (CHA), compound of platelet-rich fibrinand coralline hydroxyapatite, compound of autologous bone and coralline hydroxyapatiteand pure coralline hydroxyapatite (control group). By comparing the osteogenesis of fourgroups materials on the process of bone defects, we providea theoretical basis andoperating instructions of these bone transplantation materials for the clinical application.Methods: Six international standard male Beagles were selected and four standard bonedefects with diameters of6mm and depth of5mm were prepared on each side of tibialmetaphyseal of Beagles respectively. The four bone defects were divided into A, B, C andD group randomly. The rhBMP-2/CHA, PRF/CHA, autologous bone/CHA and pure CHAwere implanted into the bone defects at the same time; after bone transplantation,tetracycline, calcein, alizarin red and xylenol orange fluorescein subcutaneous fluorescentsignals were injected into the necks of Beagles at the2nd,4th,8th and12th weekrespectively. The six Beagles were executed after12weeks to get samples. Using grossspecimen and dental CT to compare four groups bone growth in bone graft areas and bonemineral density, and decalcified paraffin section, HE staining were used to observe histolo-gical characteristics of new bones in graft areas percentages of new bone trabecular areasin bone graft areas were measured to, compare the formation of new bones in graft areasfrom four groups after12weeks; no decalcified hard tissue grinding was used to observefluorescent tags on bone graft areas by fluorescence microscope, rates of fluorescent tagson bone graft areas were measured and compared at different times. the distance between different fluorescence belts and calculating were measured than comparing the averagemineralized deposition rates of new bones on graft areas.Results:1. Six beagles were alive after operation; there was no surgical infected; diet andactivities was normal; after12weeks of operation, there was no significant difference inbone graft areas of four groups gross specimen; bone grew well; the space between bonedefects were completely closed; there was a clear boundary between planted bone area andthe host bone in each defect.X-ray showed: there were no obvious transmission shadows about mal-osteogenesis inbone graft areas of four groups; new bones was connected closely with natural bones; allbone graft areas density were not the same; The bone density was more dense ofautologous bone/CHA group and PRF/CHA group, the next for rhBMP-2/CHA group, andthere is no significant dense bone density shadow in CHA group.3. HE staining showed that12weeks after operation, there was no apparent tissue necrosisand inflammatory cell infiltration; there were different number of new bone tissues anddegradation of bones; new bones and host bones were connected closelyand no clearboundary was found; compared with host bones, thickness of new bone trabecular wasirregular, varied, and the arrangement was disorderly; compared with CHA group, newbone trabeculars on bone graft areas of other three groups were more dense, thick, withbetter consecutiveness;12weeks after operation, osteogenesis quantity on bone graftareasof four groups were compared as following: autologous bone/CHA group> PRF/CHA group> rhBMP-2/CHA group> CHA group.4. Undecalcified hard tissue grinding showed that: there were orange fluorescent belts ongraft areas, which meant that new bone was formed in two weeks after operation; theamount of new bone formations on graft areas in four groups at two weeks after operationwere compared as follow: autologous bone/CHA group> PRF/CHA group≈rhBMP-2/CHA group> CHA group; there were green fluorescent belts on each graft area, whichwere much more than orange fluorescent belts of themselves,which meant the osteogenic capability of each groups was improved at two to four weeks after operation; the amount ofnew bone formations on graft areas in four groups at two-four weeks after operation werecompared as follow: autologous bone/CHA group> PRF/CHA group≈rhBMP-2/CHAgroup> CHA group; there were red fluorescent belts on graft areas, which meant theamount of new bones in each groups increased at four to eight weeks after operation; theamount of new bone formations on graft areas in four groups at four to eight weeks afteroperation were compared as follow: PRF/CHA group> autogenous bone/CHA group>PRF/CHA group> CHA group. The average mineralized deposition rates of new bones ongraft areas in four groups were compared as follow: autologous bone/CHA group>PRF/CHA group≈rhBMP-2/CHA group> group CHA; At four to eight weeks afteroperation, the average mineralized deposition rates of new bones on graft areas in fourgroups: PRF/CHA group> autologous bone/CHA group> rhBMP-2/CHA group> CHAgroup.Conclusion:1. New bones in the four groups of bone graft areas were formed in twoweeks after operation, and the amount of new bones was growing with time.2. The osteogenesis effects of three kinds of composite bone graft materials were muchbetter than that of using coral hydroxyapatite alone.3.Autologous bone/CHA group was the best in the osteogenesis effects of three kinds ofcomposite bone graft materials, and that of PRF/CHA group was followed by, rhBMP-2/CHA group was the last.4.Autologous bone/CHA group has the best osteogenesis effect at four to eight weeks afteroperation, then it was declined gradually.5. The osteogenesis ability of PRF/CHA group still was well at eight week after operation.6.The osteogenesis ability of rhBMP-2/CHA group had decreased obviously after4th weekof operation.