Osteoblastic and anti-osteoclastic activities of strontium-substituted silicocarnotite ceramics: In vitro and in vivo studies

Osteoporosis bone defect is a refractory orthopaedic disease which characterized by impaired bone quality and bone regeneration capacity.Current therapies,including antiosteoporosis drugs and artificial bone grafts,are not always satisfactory.Herein,a strontium-substituted calcium phosphate silicate bioactive ceramic(Sr-CPS)was fabricated.In the present study,the extracts of Sr-CPS were prepared for in vitro study and Sr-CPS scaffolds were used for in vivo study.The cytocompatibility,osteogenic and osteoclastogenic properties of Sr-CPS extracts were characterized in comparison to CPS.Molecular mechanisms were also evaluated by Western blot.Sr-CPS extracts were found to promote osteogenesis by upregulating Wnt/β-catenin signal pathways and inhibit osteoclastogenesis through downregulating NF-κB signal pathway.In vivo,micro-CT,histological and histomorphometric observation were conducted after 8 weeks of implantation to evaluate the bone formation using calvarial defects model in ovariectomized rats.Compared with CPS,Sr-CPS significantly promoted critical sized ovariectomy(OVX)calvarial defects healing.Among all the samples,Sr-10 showed the best performance due to a perfect match of bone formation and scaffold degradation rates.Overall,the present study demonstrated that Sr-CPS ceramic can dually modulate both bone formation and resorption,which might be a promising candidate for the reconstruction of osteoporotic bone defect.