The Effect of Collagen-combined Xenogenic Bone and rhBMP-2 On Bone Regeneration and Micro-Architecture in a Critical-size Segmental Defect in the Rat Fibula

Autogenous bone is one of the most useful graft material when bone defect is remained after radical excision of tumor.  However, the amount of bone acquired from donor site is limited, so making persistent efforts to develop better bone graft materials and substitutes including allogenic bone, xenogenic bone, synthetic bone, and growth factors is required.  Recombinant human bone morphogenic protein-2(rhBMP-2) is a growth factor that belongs to the transforming growth factor-β (TGF-β) family and which has been known as having osteoinductivility.  And xenogenic bone, used popularly being substituted for autogenous bone, includes bovine bone, porcine bone, and coral exoskeleton, etc.  The purpose of this study was to compare the ability of bone regeneration between porcine-derived xenogenic bone and rhBMP-2 in a rat fibula defect model.

A more than critical size defect (7mm) of fibula was created in each of 16 male Spraque-Dawley rats.  They were all in experimental group(The experiment for control group was done in previous study).  The CollaOss^○R(Bioland, Korea), composed of porcine bone and collagen, was positioned in the left defect sites.  On the other hand, CowellBMP^○R(Cowellmedi, Korea), rhBMP-2, with absorbable collagen sponge(Ateloplug^○R, Bioland, Korea) was positioned in the right defect sites. The groups were evaluated using histologic, radiologic, and Micro-CT methods following 4- and 8-week healing intervals. 

Among the observed results for both experimental groups we can highlight the following: 

I. In the xenogenic graft models, there was no regeneration with bony reunion, but with fibrous union on both 4- and 8-weeks groups, although slight newly formed bone was seen by the histologic findings.

II. In the rhBMP-2 with absorbable collagen sponge graft models, there were complete bony regeneration on both 4- and 8-weeks groups.  Furthermore, there were overgrowth of newly formed bone on both groups, but the amount of it on 8-weeks groups was less than on 4-weeks groups with progressing favorable bony remodeling.

In conclusion, the rhBMP-2 with carrier was more effective and useful graft material than xenogenic bone.  It was considered that the xenogenic bone have just osteoconductivity, but the rhBMP-2 with carrier have the ability of both osteoconduction and osteoinduction. 

References

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