Bone formation of escherichia coli expressed rhBMP-2 on absorbable collagen block in rat calvarial defects

Abstract

[한글]

[영문]

Bone morphogenetic proteins (BMPs) have been reported to possess the osteoinductive potential for periodontal and bone regenerative therapy. Effective carrier system and mass production of recombinant human bone morphogenetic proteins (rhBMPs) for economical efficiency are required to applicate it clinically.The aim of this study was to evaluate the osteogenic and space-providing effect of rhBMP-2 produced by Escherichia coli (E. coli) expression system (ErhBMP-2) with absorbable collagen block (ACB) as the carrier system in the rat calvarial defect model.Calvarial defects of 8 mm in diameter were created in sixty male Sprague-Dawley rats. The animals were divided into 6 groups of 10 animals each and each group received one of the following experimental conditions: sham-surgery control (no material applied), ACB control (ACB alone), and ErhBMP-2/ACB (ACB loaded with 0.025mg/ml ErhBMP-2). Histological and histometric analysis were performed following 2 and 8 weeks healing intervals.The defects were filled with thin loose connective tissue in the sham-surgery control group. The ACB control group showed more bone marrows containing angioid tissue and more osteoblastic cells along the defect margin than the shamsurgery control group. Enhanced bone maturation was characteristic in the ErhBMP-2/ACB group. The newly formed bone was not distinguishable with the pre-existing bone as the healing time extended, and the degree of bone remodeling was more advanced at 8 weeks than at 2 weeks. The ErhBMP-2/ACB group showed statistically significant increase of the augmented area compared to the other groups at both 2 and8 weeks (p < 0.05). In the aspect of new bone area and bone density, the results were similar to the outcome of augmented area. The ErhBMP-2/ACB group showed significantly greater new bone area and higher bone density at both 2 and 8 weeks than the other groups, but there was no significant difference following the healing periods of 2 weeks and 8 weeks.ErhBMP-2 loaded on ACB can induce favorable bone formation in the rat calvarial defect model. However, this collagen carrier in block type did not fulfill the space maintaining expectations for bone formation by ErhBMP-2. Therefore, further studies are required to reinforce the space-providing effect of this carrier system.