Compression-Resistant Polymer/Ceramic Composite Scaffolds Augmented with rhBMP-2 Promote New Bone Formation in a Nonhuman Primate Mandibular Ridge Augmentation Model

Purpose: This study was designed to test the hypothesis that compression-resistant (CR) scaffolds augmented with recombinant human bone morphogenetic protein-2 (rhBMP-2) at clinically relevant doses in a nonhuman primate lateral ridge augmentation model enhances bone formation in a dose-responsive manner without additional protective membranes. Materials and Methods: Defects (15 mm long × 8 mm wide × 5 mm deep) were created bilaterally in the mandibles of nine hamadryas baboons. The defect sites were implanted with poly(ester urethane) (PEUR)/ceramic CR scaffolds augmented with 0 mg/mL rhBMP-2 (CR control), 0.75 mg/mL rhBMP-2 (CR-L), or 1.5 mg/mL rhBMP-2 (CR-H). The primary outcome of ridge width and secondary outcomes of new bone formation, cellular infiltration, and integration with host bone were evaluated using histology, histomorphometry, and microcomputed tomography (micro-CT) at 16 weeks following implantation. Results: New bone formation in the mandible was observed in a dose-responsive manner. CR-H promoted significantly greater new bone formation compared with the CR control group. In all groups, ridge width was maintained without an additional protective membrane. Conclusion: CR scaffolds augmented with a clinically relevant dose of rhBMP-2 (1.5 mg/mL) promoted significant new bone formation. These results suggest that a CR PEUR/ ceramic composite scaffold without a protective membrane may be a potential new rhBMP-2 carrier for clinical use. Keywords: bone graft, bone morphogenetic proteins, compression-resistant, histology, nonhuman primate, polymer, ridge augmentation