Mesoporous bioactive glass-coated 3D printed borosilicate bioactive glass scaffolds for improving repair of bone defects

Background: In the field of tissue engineering, there is currently increasing interest in new biomedical materials with high osteogenic ability and comparable mechanical function to repair bone defects. Three-dimensional (3-D) bioactive borosilicate glass (BG) scaffolds exhibit uniform interconnected macro-pores, high porosity and high compressive strength. In this study, we fabricated 3-D BG scaffolds by the 3D printing technique, then coated the surface of the 3-D BG scaffolds with mesoporous bioactive glass (MBG) (BG-MBG scaffold). Methods: The biocompatibility of the BG-MBG scaffolds was evaluated by assessing biodegradability, cell proliferation, alkaline phosphatase (ALP) activity and by quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis of osteogenic gene expression with human bone marrow stromal cells (hBMSCs). Moreover, the BG-MBG scaffolds were used to repair rat femoral defects and their performance was evaluated using microcomputed tomography (micro-CT), fluorescence labeling, histological analysis and immunohistochemical (IHC) analysis. Results: The results showed that the BG-MBG scaffolds possessed ordered nearly 4nm meso-pores and regular macro-pores, as well as good biodegradability, and that they stimulated the proliferation and osteogenic differentiation of hBMSCs. In in vivo studies, the result of micro-CT reconstructed images (BG-9M group, 0.63 ± 0.02 g/cm(3) and BG group 0.13 ± 0.02 g/cm(3) ) and van Gieson staining (BG-9M groups, 62.67 ± 3.39% and BG group, 12.33 ± 2.58%) showed that the BG-MBG scaffolds could significantly enhance new bone formation in both inner and peripheral scaffolds in defects, in and in without the presence of growth factors or stem cells (P < 0.05). Conclusions: It is believed from these results that the BG-MBG scaffolds possess excellent osteoinductive and osteogenic properties which will make them appealing candidates for bone defect repair. The novelty of our research is to provide a new material to treat bone defects in clinic.