title: Effect of amorphous silica nanoparticles on in vitro RANKL-induced osteoclast differentiation in murine macrophages.
abstract: Amorphous silica nanoparticles (nSP) have been used as a polishing agent and/or as a remineralization promoter for teeth in the oral care field. The present study investigates the effects of nSP on osteoclast differentiation and the relationship between particle size and these effects. Our results revealed that nSP exerted higher cytotoxicity in macrophage cells compared with submicron-sized silica particles. However, tartrate-resistant acid phosphatase (TRAP) activity and the number of osteoclast cells (TRAP-positive multinucleated cells) were not changed by nSP treatment in the presence of receptor activator of nuclear factor κB ligand (RANKL) at doses that did not induce cytotoxicity by silica particles. These results indicated that nSP did not cause differentiation of osteoclasts. Collectively, the results suggested that nanosilica exerts no effect on RANKL-induced osteoclast differentiation of RAW264.7 cells, although a detailed mechanistic examination of the nSP70-mediated cytotoxic effect is needed.
authors.affiliation: Laboratory of Toxicology and Safety Science, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan. tomoaki@phs.osaka-u.ac.jp.
authors.forename: Hiromi
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authors.lastname: Nabeshi
authors.forename: Tomoaki
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authors.lastname: Yoshikawa
authors.forename: Takanori
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authors.lastname: Akase
authors.forename: Tokuyuki
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authors.lastname: Yoshida
authors.forename: Saeko
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authors.lastname: Tochigi
authors.forename: Toshiro
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authors.lastname: Hirai
authors.forename: Miyuki
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authors.lastname: Uji
authors.forename: Ko-Ichi
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authors.lastname: Ichihashi
authors.forename: Takuya
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authors.lastname: Yamashita
authors.forename: Kazuma
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authors.lastname: Higashisaka
authors.forename: Yuki
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authors.lastname: Morishita
authors.forename: Kazuya
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authors.lastname: Nagano
authors.forename: Yasuhiro
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authors.lastname: Abe
authors.forename: Haruhiko
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authors.lastname: Kamada
authors.forename: Shin-Ichi
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authors.lastname: Tsunoda
authors.forename: Norio
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authors.lastname: Itoh
authors.forename: Yasuo
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authors.lastname: Yoshioka
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Tsutsumi