BMP-2 incorporated into a biomimetic coating on 3D-printed titanium scaffold promotes mandibular bicortical bone formation in a beagle dog model

Biocompatibility and osteoconductivity of porous scaffolds can be improved through coating technique by creating micro- and nanostructures on the surfaces. In this study, a biomimetic approach was used to construct a bone morphogenetic protein-2 (BMP-2) integrated calcium phosphate (CaP) coating on the surface of porous titanium scaffolds. In vitro characterizations showed that the scaffolds had mechanical properties comparable to those of the human cortical bone. The biomimetic coating has a nano-scaled surface structure, which releases BMP-2 in a stable and effective manner. Bicortical bone defects were prepared in the bilateral mandibles of beagle dogs, and the coated and uncoated scaffolds were fixed in the bone defects for 8 weeks. Based on micro-CT and histological analysis results, the biomimetic coating significantly promoted bone formation in the titanium scaffold. The coated scaffold group had significantly higher bone volume fraction, bone area fraction, and bone-to-implant contact results than the uncoated scaffold group. Besides, hematological indexes and histopathology results of the visceral organs confirmed the scaffold and coating's biocompatibility. Accordingly, the current study demonstrates that BMP-2 integrated biomimetic CaP coating can significantly promote bone formation in porous titanium scaffolds and benefit the healing process of the bicortical mandibular defect in beagle dogs.