Effect Of Exogenous Transforming Growth Factor-beta2(TGF-β₂) And Bone Morphogenetic Protein2(BMP₂) And Allografts Bone On Radius Defects Healing Of Expermental Rabbits

Objective:Freeze dried bone allografts were implanted in rabbits' 10mm mid-radius defects models.In order to research the effect of transforming growth factor-beta(TGF-β₂)and bone morphogenetic protein(BMP₂)supplementation to repair the segment bone defects To investigate the effect of exogenous transforming growth factor-beta(TGF-β₂)and bone morphogenetic protein(BMP₂)and allografts bone on radius defects.Methods:Making freeze dried bone allografts,10mm segmental bone and periosteum defects were created in 40 New Zealand rabbits on bilateral radius and were treated with 4 different metheds.The model of adult rabbits radius defects were made and treated with TGF-β₂ and BMP₂ respectively or in combination in the radius defects:A group:BMP₂ and allografts bone.B group:autogenous bone.C group:TGF-β₂ and allografts bone.D group:BMP₂ and TGF-β₂ and allografts bone.The repaires of defects were observed through body looking by naked eyes,radiology,the bone mineral density(BMD),calcium content in callus in bone defects and histologic sections at 4,8,10,12 week after operations;biomechanical tests were made only at 12 week.Result:Every group have no obvious immunal transplanting rejection.B group excelled A,C,D group in aspects of calcium content in callus,the ability of radius defects and biomechanical strength of bone(P＜0.01).The effect of C group was better than that of A group(P＜0.01), while D group brought better result than A and C group(P＜0.05).All radius detects were healed in B,D groups at 12 week.But Callus and new bone formation,cartilage ossification,formation of marrow cavity in C group were earlier than in A groups.A group radius were repaired more thoroughly in 12 week than C group after operation.D groups's radiogrophs were close to B groups'.A group only formed a little new bone at edges of bone defects and filled with some soft tissue,and could not healing at 12 week.The BMDs in C group were obviously higher than A group at 8 week and 10 week(P＜0.01).A,Cgroup were lower than D group at the same periods and the difference at 10 week and 12 week had statistical significance(P＜0.01 and P＜0.05).Histological examinations showed that vascular formation,osteoblast differentiation and proliferation,callus formation and remolding etc were all earlier than D group at the same periods,and had no obvious difference to B group.The defects treated with A,C group could not get osseous-tissue healing.The biomechanical test at 12 week results also showed maximum stresses of three points curving were higher in groups D than in group A,C(P＜0.05),and had no obvious difference to B group.Conclusion:TGF-β₂ and BMP₂ are played an important role on radius defects healing. Fracture healing and callus content and mechanics intensity can be conspicuous promoted by local application of exlgenous TGF-β₂ and BMP₂,meanwhile,the time of fracture healing can get close the time of autogenous utmostly,decurtating the healing time of patient of need graft bone on clinically.Callus content and the effect of TGF-β₂ is better than that of BMP₂.The result will be further enhanced if they are applied together with synergistic effect on radius defects.At the same time,it was provided dependable index for determiner metrology and which agent recombination with allograft bone.