title: In vitro study of the biological interface of Bio-Oss: implications of the experimental setup.
abstract: OBJECTIVE
  To systematically investigate the biological interface of Bio-Oss by analysing dissolution-precipitation behaviour and osteogenic responses using in vitro experimental systems.
  
  
  METHODS
  Different concentrations (1-100 mg/ml) of Bio-Oss were incubated in cell culture medium for 24 h before elemental concentrations for calcium, phosphorus and silicon in the medium were analysed with inductive coupled plasma-optical emission spectroscopy. Radioactive calcium-45 isotope labelling technique was used to study possible precipitation of calcium on the Bio-Oss particle. Biological interface of Bio-Oss was studied in osteogenic experiments using mineralization medium and three different sources of cells (primary mouse bone marrow stromal cells, primary rat calvarial cells and MC3T3-E1 mouse pre-osteoblast cell line). Cells were fixed and stained with Toulidine blue, von Kossa or Alizarin Red staining for confirmation of extracellular matrix mineralization.
  
  
  RESULTS
  Elemental analysis of the cell culture medium demonstrated a significant decrease of calcium and phosphorus and a dose-dependent release of silicon to the medium after incubation with Bio-Oss. A significant decrease of calcium and phosphorus in the medium occurred even at low concentrations of Bio-Oss. Uptake of calcium on the Bio-Oss particle was confirmed with radioactive calcium-45 isotope labelling technique. In osteogenic experiments with Bio-Oss (<1 mg/ml), matrix mineralization around the Bio-Oss particles were demonstrated in all three cell types with von Kossa and Alizarin Red staining.
  
  
  CONCLUSIONS
  Dissolution-precipitation reactions occur at the surface of Bio-Oss, and osteogenic responses are seen at the biological interface. The concentration of Bio-Oss is a key factor for the experimental in vitro results, and may also have implications for the clinic.
authors.affiliation: Department of Odontology, Umeå University, S-901 87 Umeå, Sweden. zivko.mladenovic@odont.umu.se
authors.forename: Živko
authors.initials: Ž
authors.lastname: Mladenović
authors.forename: Annika
authors.initials: A
authors.lastname: Sahlin-Platt
authors.forename: Britta
authors.initials: B
authors.lastname: Andersson
authors.forename: Anders
authors.initials: A
authors.lastname: Johansson
authors.forename: Erik
authors.initials: E
authors.lastname: Björn
authors.forename: Maria
authors.initials: M
authors.lastname: Ransjö
mesh_terms: D000818:Animals; D018786:Bone Substitutes / Q000737:chemistry; D002132:Calcium Radioisotopes; D002460:Cell Line; D002478:Cells, Cultured; D003470:Culture Media / Q000737:chemistry*; D066298:In Vitro Techniques; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D051379:Mice; D008903:Minerals / Q000737:chemistry*; D010006:Osteoblasts / Q000378:metabolism*; D010012:Osteogenesis / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D013054:Spectrophotometry, Atomic; D013194:Staining and Labeling
chemical_list: C077540:Bio-Oss; D018786:Bone Substitutes; D002132:Calcium Radioisotopes; D003470:Culture Media; D008903:Minerals