Effects of strontium ions with potential antibacterial activity on in vivo bone regeneration
Abstract Background Bioactive glasses (BGs) have attracted added attention in the structure of the scaffolds for bone repair applications. Different metal ions could be doped in BGs to induce specific biological responses. Among these ions, strontium (Sr) is considered as an effective and safe doping element with promising effects on bone formation and regeneration. Methods In this experiment, we evaluated the antibacterial activities of the gelatin-BG (Gel-BG) and Gel-BG/Sr scaffolds in vitro. The osteogenic properties of the prepared scaffolds were also assessed in rabbit calvarial bone defects for 12 weeks. Alizarin Red, Hematoxylin & Eosin (H&E) and Masson’s Trichrome staining were performed to assess bone regeneration and the obtained results were compared with those without Sr. Also, histomorphometric data were obtained to evaluate the new bone, residual graft, and connective tissue. Results Both scaffolds showed in vivo bone formation during 12 weeks with the newly formed bone area in Gel-BG/Sr scaffold was higher than that in Gel-BG scaffolds after the whole period. Based on the histological results, Gel-BG/Sr exhibited acceleration of early-stage bone formation in vivo. The results of antibacterial investigation showed that although both Gel-BG/Sr and Gel-BG effectively inhibited the growth of Escherichia coli (E. coli) but, only Gel-BG/Sr structure could lead to a 3 log reduction in Staphylococcus aureus (S. aureus). Conclusions: Our results confirmed that Sr doped BG is a favorable candidate for bone tissue engineering with superior antibacterial activity and bone regeneration capacity compared with similar counterparts having no Sr ion.