title: Morphological and functional changes in RAW264 macrophage-like cells in response to a hydrated layer of carbonate-substituted hydroxyapatite.
abstract: Synthetic hydroxyapatite (HAp) is used clinically as a material for bone prostheses owing to its good bone-bonding ability; however, it does not contribute to bone remodeling. Carbonate-substituted hydroxyapatite (CAp) has greater bioresorption capacity than HAp while having similar bone-bonding potential, and is therefore considered as a next promising material for bone prostheses. However, the effects of the CAp instability on inflammatory and immune responses are unknown in detail. Here, we show that the surface layer of CAp is more hydrated than that of HAp and induces changes in the shape and function of macrophage-like cells. HAp and CAp were synthesized by wet method and molded into disks. The carbonate content of CAp disks was 6.2% as determined by Fourier transform (FT) infrared spectral analysis. Diffuse reflectance infrared FT analysis confirmed that physisorbed water and surface hydroxyl groups (OH-) were increased whereas structural OH-was decreased on the CAp as compared to the HAp surface. The degree of hydroxylation in CAp was comparable to that in bone-apatite structures, and the CAp surface exhibited greater hydrophilicity and solubility than HAp. We investigated immune responses to these materials by culturing RAW264 cells (macrophage precursors) on their surfaces. Cell spreading on the CAp disk was suppressed and the secretion level of inflammatory cytokines was reduced as compared to cells grown on HAp. These results indicate that the greater surface hydration of CAp surface can attenuate adverse inflammatory responses to implanted bone prostheses composed of this material. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1063-1070, 2017.
authors.affiliation: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-0062, Japan.|Department of Applied Chemistry, School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Igeta
authors.affiliation: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-0062, Japan.|Department of Life and Environmental Sciences, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Kuwamura
authors.affiliation: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-0062, Japan.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Horiuchi
authors.affiliation: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-0062, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Nozaki
authors.affiliation: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-0062, Japan.|Department of Life and Environmental Sciences, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan.
authors.forename: Daichi
authors.initials: D
authors.lastname: Shiraishi
authors.affiliation: Department of Applied Chemistry, School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Aizawa
authors.affiliation: Department of Life and Environmental Sciences, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Hashimoto
authors.affiliation: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-0062, Japan.
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Yamashita
authors.affiliation: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-0062, Japan.
authors.forename: Akiko
authors.identifier: 0000-0002-0813-7728
authors.initials: A
authors.lastname: Nagai
mesh_terms: D000818:Animals; D002254:Carbonates / Q000737:chemistry*; D016207:Cytokines / Q000378:metabolism; D017886:Durapatite / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D007249:Inflammation / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D008422:Materials Testing; D051379:Mice; D000067996:RAW 264.7 Cells
chemical_list: D002254:Carbonates; D016207:Cytokines; D017886:Durapatite
keywords: RAW264 cells; carbonated hydroxyapatite; cell morphology; cytokine; surface hydration