Bone formation of middle ear cavity using biphasic calcium phosphate lyophilized with Escherichia coli-derived recombinant human bone morphogenetic protein 2 using animal model.

Objective: The aim of the study was to analyze the value of Escherichia coli-derived recombinant human bone morphogenetic protein-2 (ErhBMP-2) coated biphasic calcium phosphate (BCP) for the obliteration of middle ear bone defect after mastoid surgery.

Methods: Twenty-four specific pathogen-free Sprague-Dawley rats were randomly assigned to the BCP group (n=12) and BCP-ErhBMP-2 group (n=12; in which BCP scaffold of the granular type was coated with ErhBMP-2). In both groups, BCP scaffold was used to surgically fill the middle ear bulla. New bone formation was evaluated by measuring bone density (%) after 4 and 8 weeks in all rats in both groups.

Results: At 4 weeks, new bone was visible at the periphery and center of the middle ear cavity in both groups. In the BCP group, a moderate amount of fibrous tissue had infiltrated into the interspace of the scaffolds. New bone almost totally filled the interspace in the BCP-ErhBMP-2 group. At 8 weeks, copious new bone formation had occurred. Histometric measurements showed that bone density in the BCP group was smaller than in the BCP-ErhBMP-2 group at 4 weeks (25.10% and 38.43%, respectively; p<0.05) and 8 weeks (25.54% and 34.18%, respectively; p<0.05).

Conclusions: New bone formation was greater in the presence of BCP-ErhBMP-2 scaffolds. ErhBMP-2 coated BCP scaffolds is a potentially useful material for middle ear obliteration after mastoidectomy.