Co-modified 3D printed β-tricalcium phosphate with magnesium and selenium promotes bone defect regeneration in ovariectomized rat

Magnesium (Mg) and Selenium (Se) are essential elements for bone health and have been studied extensively for its powerful osteogenesis and promoting bone regeneration. The purpose was to observe whether Co-modified 3D-printed β-tricalcium phosphate with Mg and Se could promote bone defect regeneration in an ovariectomized(OVX) rat model. The MC3T3-E1 cells were co-cultured with the leachate of β-TCP, Mg-TCP, and Mg/Se-TCP and induced to osteogenesis, and the cell viability, ROS, and osteogenic activity were observed by Cell Count Kit-8(CCK-8), fluorescent probe 2′, 7′-dichlorofluorescin diacetate, Alkaline phosphatase (ALP) staining, Alizarin Red(RES) staining, western blotting(WB), and immunofluorescence. Then the β-TCP, Mg-TCP, and Mg/Se-TCP were implanted into the femoral epiphysis bone defect model of OVX rats for 12 weeks. Micro-CT and histology analysis were used to observe the therapeutic effect. In vitro results show that the cell mineralization and osteogenic activity of the Mg/Se-TCP group is significantly higher than the β-TCP group and Mg-TCP group. Protein expressions such as FOxO1, SIRT1, SOD2, Runx-2, Cola1a, and OC of the Mg/Se-TCP group are significantly higher than the Con group and the β-TCP group. The results of intracellular ROS and SIRT1 and SOD2 immunofluorescence showed that Mg/Se-TCP can restore the oxidative stress balance of osteoblasts. Micro-CT and histology analysis showed that treatment with Mg/Se-TCP showed the largest amount of bone tissue in the defect area (p < 0.05), and exhibited lower values of residual biological material (p < 0.05), compared to that of the β-TCP group and Mg-TCP group. Our research results confirm that Mg/Se-TCP can improve the activity and function of osteoblasts and enhance bone regeneration mediated by reducing intracellular ROS in OVX rat models. GRAPHICAL ABSTRACT: [Figure: see text]