title: Pyrophosphate Stimulates Differentiation, Matrix Gene Expression and Alkaline Phosphatase Activity in Osteoblasts.
abstract: Pyrophosphate is a potent mitogen, capable of stimulating proliferation in multiple cell types, and a critical participant in bone mineralization. Pyrophosphate can also affect the resorption rate and bioactivity of orthopedic ceramics. The present study investigated whether calcium pyrophosphate affected proliferation, differentiation and gene expression in early (MC3T3 pre-osteoblast) and late stage (SAOS-2 osteosarcoma) osteoblasts. Pyrophosphate stimulated peak alkaline phosphatase activity by 50% and 150% at 100μM and 0.1μM in MC3T3, and by 40% in SAOS-2. The expression of differentiation markers collagen 1 (COL1), alkaline phosphatase (ALP), osteopontin (OPN), and osteocalcin (OCN) were increased by an average of 1.5, 2, 2 and 3 fold, by high concentrations of sodium pyrophosphate (100μM) after 7 days of exposure in MC3T3. COX-2 and ANK expression did not differ significantly from controls in either treatment group. Though both high and low concentrations of pyrophosphate stimulate ALP activity, only high concentrations (100μM) stimulated osteogenic gene expression. Pyrophosphate did not affect proliferation in either cell type. The results of this study confirm that chronic exposure to pyrophosphate exerts a physiological effect upon osteoblast differentiation and ALP activity, specifically by stimulating osteoblast differentiation markers and extracellular matrix gene expression.
authors.affiliation: Division of Applied Material Science, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Michael
authors.initials: M
authors.lastname: Pujari-Palmer
authors.affiliation: Division of Applied Material Science, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Shiuli
authors.initials: S
authors.lastname: Pujari-Palmer
authors.affiliation: Division of Applied Material Science, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Xi
authors.initials: X
authors.lastname: Lu
authors.affiliation: Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lind
authors.affiliation: Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Håkan
authors.initials: H
authors.lastname: Melhus
authors.affiliation: Stockholm Craniofacial Centre, Department of Reconstructive Plastic Surgery, Karolinska University Hospital, Stockholm, Sweden.|Department of Materials Chemistry, Polymer section, Uppsala University, Uppsala, Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Engstrand
authors.affiliation: Division of Applied Material Science, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Marjam
authors.initials: M
authors.lastname: Karlsson-Ott
authors.affiliation: Division of Applied Material Science, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Hakan
authors.initials: H
authors.lastname: Engqvist
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism*; D000818:Animals; D015415:Biomarkers; D002113:Calcification, Physiologic; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D011756:Diphosphates / Q000378:metabolism / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D051379:Mice; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism*; D010012:Osteogenesis
chemical_list: D015415:Biomarkers; D011756:Diphosphates; D016326:Extracellular Matrix Proteins; D000469:Alkaline Phosphatase