3D Bioprinted Cellular Scaffolds Containing Monetite for the Treatment of Critical Bone Defects.

Repairing critical bone defects is a clinical challenge that urgently needs to be addressed. 3D bioprinting strategies using bioinks composed of living cells and hydrogel biomaterials can mimic natural tissues, offering a novel repair approach. In particular, the freeform reversible embedding of suspended hydrogels (FRESH) technique employs a support bath to stabilize mechanically weak hydrogels during printing while maintaining their biocompatibility. In this study, we fabricated a 3D bioprinter, and prepared a bioink composed of monetite, sodium alginate, and hydroxypropyl methylcellulose. The rheological properties of the bioink were subsequently evaluated to ensure its printability. Following 3D printing, the chemical compositions and microstructures of the scaffolds generated from the bioink were analyzed to confirm their suitability for cell growth applications. We further incorporated rat bone marrow stem cells into the bioink to create 3D bioprinted cellular scaffolds. Preliminary in vitro tests demonstrated the excellent biocompatibility and early osteogenic induction capabilities of the scaffolds. These 3D bioprinted cellular scaffolds were subsequently implanted into a rat skull defect model, and radiological and histological analyses revealed that the combination of monetite and rat bone marrow stem cells synergistically enhanced osteogenesis in vivo. Our study was the first to apply FRESH to in vivo osteogenesis, demonstrating that 3D bioprinted cellular scaffolds containing monetite promoted bone regeneration and provided a novel strategy for the clinical translation of bone regeneration.