3D-Printed Triply Periodic Minimal Surface Ceramic Scaffold Loaded With Bone Morphogenetic Protein-2 and Zoledronic for Cranium Defect Repairment

Managing large, critical-sized bone defects poses a complex challenge, especially when autografts are impractical due to their size and limited availability. In such situations, the development of synthetic bone implants becomes crucial. These implants can be carefully designed and manufactured as potential bone substitutes, offering controlled parameters such as porosity, hardness, and osteogenic cues. In this study, we employed digital light processing (DLP) technology to construct an alumina ceramic scaffold featuring a triply periodic minimal surface (TPMS) structure for bone transplantation. The scaffold was filled with type I collagen to enhance cell infiltration [1], thereby increasing the total surface area. In addition, type I collagen is a carrier for both bone morphogenetic protein-2 (BMP-2) and zoledronic acid (ZA). Using a clinically relevant rabbit cranium defect model, the scaffold underwent in vivo assessment for its functionality in repairing critical-sized bone defect (approximately 8 mm). Four groups of animal experiments were carried out including the control group, the gyroid scaffold group, the type I collagen-loaded scaffold group, and the bioactive factor-functionalized scaffold group. Our animal-based study results revealed that the gyroid scaffold, functionalized with bioactive molecules, provided a conductive surface for promoting increased bone formation and enhancing the healing process in critical-sized long bone and cranium defects. These findings offer preclinical evidence, supporting the use of a TPMS structure composite scaffold and present compelling support for its application as an advanced synthetic bone substitute in the future.