Effect of BioAggregate on Receptor Activator of Nuclear Factor-Kappa B Ligand–induced Osteoclastogenesis from Murine Macrophage Cell Line In Vitro

• BioAggregate suppressed RANKL-induced osteoclast formation and bone resorption.
• BioAggregate inhibited RANKL-induced expression of osteoclast-related genes.
• BioAggregate attenuated RANKL-induced TRAF6 recruitment and MAPK activation.
• BioAggregate decreased RANKL-induced nuclear translocation of c-Fos and NFATc1.
• BioAggregate shows promising therapeutic potential in root repair.

IntroductionThis study aimed to investigate the effect of BioAggregate, a calcium silicate–based nanoparticulate bioceramic, on the regulation of receptor activator of nuclear factor-kappa B ligand (RANKL)–induced osteoclast differentiation and bone resorption in vitro, as well as to delineate the underlying molecular mechanism. The performance of BioAggregate was compared with that of ProRoot mineral trioxide aggregate (MTA).MethodsCells of a murine macrophage cell line RAW 264.7 were treated with various concentrations of BioAggregate and MTA extracts. Cytotoxicity of material extracts was evaluated with Cell Counting Kit-8 assay. RANKL-induced osteoclast differentiation and function were assessed with tartrate-resistant acid phosphatase staining, F-actin staining, and lacunar resorption pits assay. The mRNA expression associated with osteoclast function was detected with quantitative real-time polymerase chain reaction. Related molecular signaling pathways were investigated with Western blot and immunofluorescence.ResultsBioAggregate extracts dose-dependently inhibited RANKL-induced osteoclast formation and resorption capacity without evident cytotoxicity. RAW 264.7 cells exposed to BioAggregate extracts also presented a decrease in RANKL-stimulated mRNA expression of osteoclast-related genes and transcription factors. Moreover, cells treated with BioAggregate extracts exhibited attenuated TRAF6 expression, suppressed mitogen-activated protein kinase signaling, and decreased nuclear translocation of NFATc1 and c-Fos in the presence of RANKL. Comparable effects were induced by MTA.ConclusionsBioAggregate and MTA exhibit comparable inhibitory effect on osteoclast differentiation and function in vitro, and our findings provide valuable insights into the mechanism of bioceramic-mediated anti-osteoclastogenic activity.