Bioactive glass nanoparticles (BGNs) are well-recognized multifunctional biomaterials for bone tissue regeneration due to their capability to stimulate various cellular processes through released biologically active ions. Understanding the correlation between BGN composition and cellular responses is key to developing clinically usable BGN-based medical devices. This study investigated the influence of CaO content of binary SiO₂-CaO BGNs (CaO ranging from 0 to 10 mol%) on osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) and in vivo bone regeneration in zebrafish osteoporosis model. The results showed that BGNs could promote osteogenic differentiation of rBMSCs by indirectly releasing active ions or directly interacting with rBMSCs by internalization. In both situations, BGNs of a higher CaO content could promote the osteogenic differentiation of rBMSCs to a greater extent. The internalized BGNs could activate the transcription factors RUNX2 and OSX, leading to the expression of osteogenesis-related genes. The results in the zebrafish osteoporosis model indicated that the presence of BGNs of higher CaO contents could enhance bone regeneration and rescue dexamethasone-induced osteoporosis to a greater extent. These findings demonstrate that BGNs can stimulate osteogenic differentiation of rBMSCs by releasing active ions or internalization. A higher CaO content facilitates osteogenesis and bone regeneration of zebrafish as well as relieving dexamethasone-induced osteoporosis. The zebrafish osteoporosis model can be a potent tool for evaluating the in vivo bone regeneration effects of bioactive materials. Statement of significance: Bioactive glass nanoparticles (BGNs) are increasingly used as fillers of nanocomposites or as delivery platforms of active ions to regenerate bone tissue. Various studies have shown that BGNs can enhance osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) by releasing active ions. However, the correlation between BGN composition and cellular responses and in vivo bone regeneration effect has still not been well investigated. Establishment of a suitable in vivo animal model for investigating this correlation is also challenging. The present study reports the influence of CaO content in binary SiO₂-CaO BGNs on osteogenic differentiation of BMSCs extracellularly and intracellularly. This study also demonstrates the suitability of zebrafish osteoporosis model to investigate in vivo bone regeneration effect of BGNs.

Bisphosphonates (BPs) are commonly used to treat skeletal diseases. However, long-term use of BPs can lead to BP-related jaw bone necrosis (BRONJ), particularly in patients undergoing tooth extraction surgery. The treatment of BRONJ remains challenging due to the local inflammatory microenvironment. To address this issue, we developed catechol-conjugated chitosan-based hydrogels incorporating cerium-doped mesoporous bioactive glass nanoparticles (Ce-MBGNs) and apoptotic extracellular vesicles (ApoEVs). The hydrogels containing 1 wt % Ce-MBGNs demonstrated biodegradability and non-cytotoxicity. The incorporation of Ce-MBGNs did not significantly impact gelation and rheological behavior. By leveraging the effects of Ce-MBGNs on regulating macrophage polarization and ApoEVs on mediating macrophage chemotaxis, hydrogels containing 1 wt % Ce-MBGNs and 1 mg/mL ApoEVs were able to recruit inflammatory macrophages and promote their M2 polarization. The in vivo experiments using a Zometa (ZA)-induced mice BRONJ model revealed that the synergistic effects of Ce-MBGNs and ApoEVs enhanced M2 polarization while reducing M1 polarization. This resulted in improved mucosal healing, bone regeneration, and alleviation of osteonecrosis. Overall, our study offers a new strategy for BRONJ therapy by addressing the inflammatory environment. Catechol-conjugated chitosan-based hydrogels containing Ce-MBGNs and ApoEVs have demonstrated impressive potential in the alleviation of BRONJ.