title: Dose-dependent osteogenic effect of octacalcium phosphate on mouse bone marrow stromal cells.
abstract: Octacalcium phosphate (OCP) has been advocated to be a precursor of biological apatite crystals in bones and teeth. Our previous studies showed that synthetic OCP stimulates bone regeneration, followed by the progressive conversion of OCP into hydroxyapatite (HA), when implanted in bone defects. However, the precise mechanism to induce the osteogenic phenotype in osteoblasts by OCP has not been identified. The present study was designed to investigate whether the physicochemical aspect, specific to and derived from the structural properties of OCP, influences the function of an osteoblastic cell line, mouse bone marrow stromal ST-2 cells. Different amounts of synthetic OCP and synthetic sintered ceramic HA were coated onto 48-well tissue culture plates. The amounts of OCP and HA were controlled to strengthen their intrinsic physicochemical properties, in which the milieu around the crystals will be modified during the culture. The roughness of the OCP coatings was independent of the amount of coating. Chemical analyses of the supernatants of the OCP coatings revealed that the concentration of Ca2+ decreased with increasing amounts of OCP, while the concentration of inorganic phosphate increased markedly, most probably through OCP--apatite conversion. ST-2 cells were cultured on the OCP or HA coatings up to day 21. The OCP coating caused a significant decrease in cell attachment and in the initial stage of proliferation, dependent upon the amount of coating. On the other hand, OCP enhanced the expression of osteogenic markers, including type I collagen, alkaline phosphatase, and osterix. However, HA did not alter the expression of these markers in ST-2 cells cultured on different amounts of HA coating. These results demonstrated that OCP is capable of inducing the differentiation of stromal cells into osteoblastic cells, especially differentiation into early stage osteoblastic cells, prior to reaching the stage of mature osteoblastic cell lineage.
authors.affiliation: Division of Craniofacial Function Engineering, Tohoku University Graduate School of Dentistry, Sendai, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Anada
authors.forename: Takashi
authors.initials: T
authors.lastname: Kumagai
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Honda
authors.forename: Taisuke
authors.initials: T
authors.lastname: Masuda
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Kamijo
authors.forename: Shinji
authors.initials: S
authors.lastname: Kamakura
authors.forename: Nobuhito
authors.initials: N
authors.lastname: Yoshihara
authors.forename: Tsunemoto
authors.initials: T
authors.lastname: Kuriyagawa
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Shimauchi
authors.forename: Osamu
authors.initials: O
authors.lastname: Suzuki
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology* / Q000201:enzymology / Q000648:ultrastructure; D002118:Calcium / Q000378:metabolism; D002130:Calcium Phosphates / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D020099:Coated Materials, Biocompatible / Q000494:pharmacology; D003470:Culture Media; D017886:Durapatite / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D051379:Mice; D008855:Microscopy, Electron, Scanning; D010012:Osteogenesis / Q000187:drug effects*; D010758:Phosphorus / Q000378:metabolism; D017154:Stromal Cells / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D013499:Surface Properties / Q000187:drug effects
chemical_list: D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; D003470:Culture Media; C022045:octacalcium phosphate; D010758:Phosphorus; D017886:Durapatite; D007770:L-Lactate Dehydrogenase; D000469:Alkaline Phosphatase; D002118:Calcium