title: Surrogate Outcome Measures of In Vitro Osteoclast Resorption of β Tricalcium Phosphate.
abstract: Introduction of porosity to calcium phosphate scaffolds for bone repair has created a new challenge when measuring bioresorption in vitro, rendering traditional outcome measures redundant. The aim of this study is to identify a surrogate endpoint for use with 3D scaffolds. Murine RAW 264.7 cells are cultured on dense discs of β-tricalcium phosphate in conditions to stimulate osteoclast (OC) formation. Multinucleated OCs are visible from day 6 with increases at days 8 and 10. Resorption pits are first observed at day 6 with much larger pits visible at days 8, 10, and 12. The concentration of calcium ions in the presence of cells is significantly higher than cell-free cultures at days 3 and 9. Using linear regression analysis, Ca ion release could account for 35.9% of any subsequent change in resorption area. The results suggest that Ca ion release is suitable to measure resorption of a beta-tricalcium phosphate ceramic substrate in vitro. This model could replace the more accepted resorption pit assay in circumstances where quantification of pits is not possible, e.g., when characterizing 3D tissue engineered bone scaffolds.
authors.affiliation: School of Nursing and Midwifery, Medical Biology Centre, 97, Lisburn Road, Belfast, BT9 7BL, UK.
authors.forename: Susan A
authors.initials: SA
authors.lastname: Clarke
authors.affiliation: School of Mechanical and Aerospace Engineering, Queen's University Belfast, Ashby Building, Stranmillis Rd, Belfast, BT9 5AH, UK.
authors.forename: Joanne
authors.initials: J
authors.lastname: Martin
authors.affiliation: School of Biological Sciences, Queens University Belfast, MBC, 97 Lisburn Rd, Belfast, BT9 7BL, UK.
authors.forename: John
authors.initials: J
authors.lastname: Nelson
authors.affiliation: LMCPA, Université Valencienne, Maubeuge, 59313, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Hornez
authors.affiliation: Skeletal Substitutes Group, RMS Foundation, Bischmattstr. 12, CH-2544, Bettlach, Switzerland.
authors.forename: Marc
authors.initials: M
authors.lastname: Bohner
authors.affiliation: School of Mechanical and Aerospace Engineering, Queen's University Belfast, Ashby Building, Stranmillis Rd, Belfast, BT9 5AH, UK.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Dunne
authors.affiliation: School of Mechanical and Aerospace Engineering, Queen's University Belfast, Ashby Building, Stranmillis Rd, Belfast, BT9 5AH, UK.
authors.forename: Fraser
authors.initials: F
authors.lastname: Buchanan
mesh_terms: D000818:Animals; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002130:Calcium Phosphates / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D008422:Materials Testing; D051379:Mice; D010010:Osteoclasts / Q000378:metabolism*; D000067996:RAW 264.7 Cells; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D002130:Calcium Phosphates; C485817:beta-tricalcium phosphate; D002118:Calcium
keywords: calcium phosphate; osteoclasts; outcome measures; porous; resorption