3D-printed scaffolds with ROS-clearing capacity for critical-sized bone defect regeneration

The repair of critical-size bone defects remains a major challenge in the field of biomedical tissue rehabilitation. Within the injured tissue microenvironment, inflammation and cellular apoptosis trigger the accumulation of reactive oxygen species (ROS), thereby impeding tissue regeneration. α-Tricalcium phosphate (α-TCP) is a biodegradable bone repair material that lacks the ability to clear excess ROS from the microenvironment of bone tissue, limiting its therapeutic efficacy. To address this issue, we developed a 3D-printed α-TCP scaffold functionalized with Manganese dioxide (MnO₂) nanoparticles to endow ROS-scavenging capability and potentiate defect repair. Characterization results confirmed the homogeneous distribution of MnO₂ within the scaffold, which facilitated efficient ROS elimination and controlled release of Mn²⁺. Additionally, MnO₂ incorporation significantly enhanced the compressive strength of the α-TCP scaffold. In vitro, the MnO₂-loaded scaffolds not only promoted the proliferation and osteogenic differentiation of bone marrow-derived mesenchymal stem cells but also protected cells against hydrogen peroxide-induced oxidative damage by reducing intracellular ROS levels. In vivo experiments using a rabbit calvarial defect model further validated that the MnO₂-modified scaffolds exhibited superior bone regeneration and osteoinductive activity relative to pure α-TCP controls. The findings indicate that α-TCP scaffolds with MnO₂ exhibit promising characteristics for bone tissue regeneration applications.