Oral and maxillofacial surgery
Bone formation of block and particulated biphasic calcium phosphate lyophilized with Escherichia coli–derived recombinant human bone morphogenetic protein 2 in rat calvarial defects

https://doi.org/10.1016/j.tripleo.2010.10.025Get rights and content

The objective of this study was to evaluate bone formation in rat calvarial defects after surgical implantation of block or particulated biphasic calcium phosphate (BCP) lyophilized with Escherichia coli–derived recombinant human bone morphogenetic protein 2 (ErhBMP-2). Critical-size calvarial osteotomy defects were created in 5 groups of Sprague-Dawley rats. Each group received one of the following: 1) sham surgery control; 2) biphasic calcium phosphate particles (CPP); 3) biphasic calcium phosphate block (CPB); 4) ErhBMP-2–coated CPP; or 5) ErhBMP-2–coated CPB. ErhBMP was coated on BCP by a stepwise lyophilizing protocol. The new bone formation was significantly greater in ErhBMP-2–treated groups compared with the untreated group. In particular, the ErhBMP-2/CPB group showed stability of augmented areas during the period of healing, due to relevant space-providing capacity. Thus, it can be concluded that CPP and CPB lyophilized with ErhBMP-2 enhance the formation of new bone, and CPB appears to be a suitable carrier for ErhBMP-2 in which a 3-dimensional structural integrity is an important consideration factor.

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Animals

One hundred male Sprague-Dawley rats (body weight 250-300 g) were used. Rats were maintained in plastic cages in a room with an ambient temperature of 21°C, with ad libitum access to water and a standard laboratory pellet diet. Animal selection and management, surgical protocol, and preparation followed routines approved by the Institutional Animal Care and Use Committee of Yonsei Medical Center, Seoul, Korea.

Expression of rhBMP-2 in E.coli

The ErhBMP-2 was produced at the research institute Cowellmedi Co., Pusan, Korea. A

Clinical observations

During the postoperative period, healing was uneventful for all animals. There were no complications, i.e., inflammatory reactions, exposure of graft material, or allergic reactions. Twelve specimens were excluded owing to technical complications during histologic processing (sham surgery control: 1 each at 2 and 8 weeks; CPP: 1 each at 2 and 8 weeks; CPP/ErhBMP-2: 1 at 2 weeks; CPB: 3 at 2 weeks and 1 at 8 weeks; and CPB/E-rhBMP-2: 1 at 2 weeks and 2 at 8 weeks). In the end, 88 specimens of

Discussion

The present study was designed to evaluate the efficacy of bone formation onto ErhBMP-2–coated HA/β-TCP particles and blocks by using an established rodent model with nonhealing calvarial defects. The findings indicate that ErhBMP-2–coated CPP and CPB promote new bone formation in a calvarial defect in rats. Even groups given CPP and CPB alone exhibited osteoconduction effects, representing direct contact between the new bone and the ceramics. These observations support earlier findings that

Conclusions

Within the limitation of this study, it can be concluded that ErhBMP-2–coated CPP and CPB enhance the formation of new bone with easy handling for application, and the CPB carrier could be successfully used for onlay indication.

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    Supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2009-0073534).

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