3D-printed Mg-1Ca/polycaprolactone composite scaffolds with promoted bone regeneration

In bone tissue engineering, polycaprolactone (PCL) is a promising material with good biocompatibility, but its poor degradation rate, mechanical strength, and osteogenic properties limit its application. In this study, we developed an Mg-1Ca/polycaprolactone (Mg-1Ca/PCL) composite scaffolds to overcome these limitations. We used a melt blending method to prepare Mg-1Ca/PCL composites with Mg-1Ca alloy powder mass ratios of 5, 10, and 20 wt%. Porous scaffolds with controlled macro- and microstructure were printed using the fused deposition modeling method. We explored the mechanical strength, biocompatibility, osteogenesis performance, and molecular mechanism of the Mg-1Ca/PCL composites. The 5 and 10 wt% Mg-1Ca/PCL composites were found to have good biocompatibility. Moreover, they promoted the mechanical strength, proliferation, adhesion, and osteogenic differentiation of human bone marrow stem cells (hBMSCs) of pure PCL. In vitro degradation experiments revealed that the composite material stably released Mg2+ ions for a long period; it formed an apatite layer on the surface of the scaffold that facilitated cell adhesion and growth. Microcomputed tomography and histological analysis showed that both 5 and 10 wt% Mg-1Ca/PCL composite scaffolds promoted bone regeneration bone defects. Our results indicated that the Wnt/β-catenin pathway was involved in the osteogenic effect. Therefore, Mg-1Ca/PCL composite scaffolds are expected to be a promising bone regeneration material for clinical application. Statement of significance: Bone tissue engineering scaffolds have promising applications in the regeneration of critical-sized bone defects. However, there remain many limitations in the materials and manufacturing methods used to fabricate scaffolds. This study shows that the developed Ma-1Ca/PCL composites provides scaffolds with suitable degradation rates and enhanced boneformation capabilities. Furthermore, the fused deposition modeling method allows precise control of the macroscopic morphology and microscopic porosity of the scaffold. The obtained porous scaffolds can significantly promote the regeneration of bone defects.