Imageological and histological assessment of biodegradation properties of CPC/DBM/rhBMP-2 composites with optimal formula / 解放军医学杂志

ABSTRACT

Objective To analyze the radiographical and histological features of implanted composites of decalcified bone matrix(DBM) impregnated with calcium phosphate cement(CPC) and recombinant human bone morphogenetic protein-2(rhBMP-2) in bone defect,and evaluate its biodegradation properties.Methods By prefabricating the rabbit DBM,the CPC/DBM/rhBMP-2 composites were prepared in a DBM/CPC ratio of 2∶8 and the rhBMP-2 content of about 1.2mg/cm3.Twenty-four rabbits were divided into groups A and B(12 each).Animals in group A were implanted with the composites in the bone defects at femoral condyle and femoral muscle,and the rabbits in group B CPC was implunted in the same place.Animals were sacrificed at 6,12 and 24 weeks after operation(4 each),and the implants were examined radiographically and histologically.Results It was shown by radiography that,in group A,the margin of implants in femoral condyle defects became irregular 6 weeks after operation;the appearance of the implants appeared hazy and shrunken in size 12 weeks after operation;and most of the implant was absorbed and the medullary cavity became partly rediotransparent 24 weeks after operation.The density of the implants in muscles beoame less dense gradually during 6 to 24 weeks after operation.While in group B,the appearance and density of the implants in femoral condyle defects and muscles were not obviously changed during 6-24 weeks after operation.Histological observation showed that,in group A,the interface between the implants in the bone defects was filled with newly formed bone grown into the composites 6 weeks after operation.New bone formed inside the composites 12 weeks after operation,and the bone defect was repaired,and most of the implants were replaced by new bones,with a little portion of it remained 24 weeks after operation.Fibrous tissue was seen to grow into the composites in muscles during 6-12 weeks after operation,and only a little of the composites remained 24 weeks after operation.In group B,no fibrous tissues or new bones grew into composites implanted in femoral condyle defects or muscles 6-12 weeks after operation,and the bone defects was still filled with materials of CPC,and no new bone or fibrous tissue was found inside CPC 24 weeks after operation.Conclusion Compare with CPC,the DBM with an optimal formula is are easy biodegradable and can be replaced by autologous bone.