3D-Printed mesoporous bioglass/ polycaprolactone scaffolds induce macrophage polarization toward M2 phenotype and immunomodulates osteogenic differentiation of BMSCs

Bioceramic composite polycaprolactone (PCL) scaffolds are widely used in bone defect repair studies. Among them, bioactive glass (BG) is considered an excellent bone-based repair material due to its unique inorganic amorphous structure, bioactivity, and osseointegration properties. However, the dense pores and low specific surface area of ordinary BGs and mesoporous BGs limit the mechanical properties and bioactivity of the overall scaffolds, and it is often necessary to increase the proportion of BGs to offset these shortcomings. Here, we prepared highly active dendritic mesoporous structured bioactive glass (MBG) with a high specific surface area (457.14 m2/g) and pore volume (1.38 cm3/g) by sol-gel method. PCL scaffolds containing different percentages of MBG were prepared by three-dimensional printing technology, and the physicochemical and immunomodulatory osteogenic properties were investigated. The results showed that the low-concentration MBG/ PCL scaffolds with 10% content (10MBG/PCL) possessed the highest compressive strength (about two times that of pure PCL scaffolds) and excellent in vitro immunomodulatory osteogenic properties. Finally, 10MBG/PCL was selected for further exploration to investigate the effects of different fiber diameters (F300, F500, F800) and pore sizes (P200, P500, P800) on the scaffolds performance. Ultimately, we found that the 10MBG/PCL scaffolds with fiber diameter and pore size of 500 μm had high osteogenic potential, significantly induced macrophage polarization toward the M2 phenotype, and downregulated the expression of inflammatory genes and that this group was the most capable of mediating macrophage polarization and thus inducing the osteogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs) to form an immune microenvironment conducive to osteogenesis. This study is a step forward in the exploration of the performance of BG composite PCL scaffolds and provides a new idea for the development of bone graft materials.