Calcium Silicate Enhances Bmscs Osteogenesis Via Mitophagy-Driven Oxphos

To reveal the molecular mechanism by which calcium silicate (CS) promotes the osteogenesis of bone marrow mesenchymal stem cells (BMSCs) from the perspective of mitochondrial metabolic patterns. CS extract was prepared, and its silicon and calcium ion concentrations were analyzed. Osteogenic differentiation assay was employed to confirm CS induced osteogenesis of BMSCs. The mitochondrial oxidative phosphorylation (OXPHOS) activity in CS-treated BMSCs was gauged by Seahorse XF Analyzers. Metabolomics analysis provided insights into metabolite changes in BMSCs exposed to CS extract. The mitochondrial profile of the treated cells was assessed using fluorescent probes: MitoTracker Green, MitoTracker Red, and the mtROS probe MitoSOX. Comprehensive evaluation of mitophagy was carried out through immunofluorescence, western blotting, transmission electron microscopy and PCR. Finally, subcutaneous transplantation and calvarial bone defect model were conducted to verify in vitro results. The release of silicon ion is indispensable for CS to induce osteogenic differentiation of BMSCs. Moreover, CS-stimulated BMSCs undergo metabolic reprogramming accompanied by increased mitochondrial OXPHOS activity, while the inhibition of OXPHOS hindered the CS-induced osteogenic differentiation of BMSCs and bone regeneration, indicating that CS-induced OXPHOS mediates the increased osteogenesis. Mechanistically, CS induced mitophagy and autophagic flux by increasing the formation of autolysosomes and lysosomal degradation to eliminate dysfunctional mitochondria and mitochondrial reactive oxygen species production, leading to enhanced OXPHOS and osteogenesis in BMSCs. CS promotes the osteogenesis of BMSCs by inducing mitophagy-mediated metabolic shifts toward OXPHOS.