title: Microscopic study on resorption of β-tricalcium phosphate materials by osteoclasts.
abstract: Sintered compounds prepared with β-tricalcium phosphate (β-TCP) are commonly used as biocompatible materials for bone regenerative medicine. Although implanted β-TCP is gradually replaced with new bone after resorption by osteoclasts, exactly how osteoclasts resorb β-TCP is not well understood. To elucidate this mechanism, we analyzed the structure of β-TCP discs on which mouse mature osteoclasts were cultured using scanning electron microscopy. We found that β-TCP was resorbed by mature osteoclasts on one side of each disc, as evidenced by the formation of multiple spine-like crystals at the exposed areas. Because osteoclasts secrete acid to resorb bone minerals, we mimicked this acidification by dipping β-TCP slices into HCl solution (pH 2.0). However, no spine-like crystals appeared even though the size of each β-TCP particle was reduced. On dentin slices, osteoclasts formed clear actin rings, which are cytoskeletal structures characteristic of bone-resorbing osteoclasts. No clear actin rings were observed in osteoclasts cultured on β-TCP slices, although small actin dots were observed. Analysis by transmission electron microscopy showed that osteoclasts attached to β-TCP particles. These results suggest that osteoclasts resorb β-TCP particles independently of clear actin ring formation.
authors: Department of Biochemistry, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.
authors: Akihiro
authors: A
authors: Matsunaga
authors: Masamichi
authors: M
authors: Takami
authors: Tarou
authors: T
authors: Irié
authors: Kenji
authors: K
authors: Mishima
authors: Katsunori
authors: K
authors: Inagaki
authors: Ryutaro
authors: R
authors: Kamijo