title: Murine osteoblastic and osteoclastic differentiation on strontium releasing hydroxyapatite forming cements.
abstract: Ionic substitutions in hydroxyapatite (HA) scaffolds and self-setting cements containing Sr(2+) ions incorporated are particularly of interest in bone regeneration. To date, the approach widely used to incorporate Sr(2+) ions into HA cements has been the addition of Sr(2+) containing salts, such as SrCO3, SrCl2∙6H2O, or SrHPO4. However, this approach is dependent upon the relative solubility of Sr(2+) containing salts with respect to calcium phosphate (CaP) precursors. Therefore, in the current study Sr(2+) substituted dicalcium phosphate dihydrate (DCPD) was first synthesized and directly reacted with tetracalcium phosphate (TTCP) to form Sr(2+) substituted HA forming cements. Rietveld refinement indicated that after one week of aging in phosphate buffered saline, cements prepared with and without Sr(2+) were composed of 75% HA and 25% unreacted TTCP by weight. Cements prepared with 10% Sr(2+) DCPD exhibited increased compressive strengths in comparison to unsubstituted cements. Increased MC3T3-E1 proliferation and differentiation were also observed on the cements prepared with increasing Sr(2+) content. It was concluded that both the scaffold microstructure and Sr(2+) ion release supported osteogenic differentiation. With respect to osteoclastic differentiation, no statistically significant differences in TRAP activity or cell morphology were observed. This suggests that the amount of Sr(2+) released may have been too low to influence osteoclast formation in comparison to unsubstituted cements. The results obtained herein demonstrate that the use of Sr(2+) substituted DCPD precursors rather than individually separate Sr(2+) containing salts may be a useful approach to prepare Sr(2+) containing HA cements.
authors.affiliation: Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA. Electronic address: sss42@pitt.edu.
authors.forename: Satish S
authors.initials: SS
authors.lastname: Singh
authors.affiliation: Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA. Electronic address: abr20@pitt.edu.
authors.forename: Abhijit
authors.initials: A
authors.lastname: Roy
authors.affiliation: Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA. Electronic address: bol11@pitt.edu.
authors.forename: Boeun
authors.initials: B
authors.lastname: Lee
authors.affiliation: Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA. Electronic address: smp116@pitt.edu.
authors.forename: Shrey
authors.initials: S
authors.lastname: Parekh
authors.affiliation: Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA; Center for Craniofacial Regeneration, University of Pittsburgh, Pittsburgh, PA 15261, USA; Department of Mechanical Engineering and Materials Science, University of Pittsburgh, PA 15261, USA; Center for Complex Engineered Multifunctional Materials, University of Pittsburgh, PA 15261, USA. Electronic address: pkumta@pitt.edu.
authors.forename: Prashant N
authors.initials: PN
authors.lastname: Kumta
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D019245:Compressive Strength; D006882:Hydroxyapatites / Q000737:chemistry*; D051379:Mice; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015675:Osteocalcin / Q000378:metabolism; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects; D053244:Osteoprotegerin / Q000378:metabolism; D000067996:RAW 264.7 Cells; D013324:Strontium / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D014961:X-Ray Diffraction
chemical_list: D006882:Hydroxyapatites; D053244:Osteoprotegerin; C475044:hydroxyapatite cement; D015675:Osteocalcin; D013324:Strontium
keywords: Differentiation; Hydroxyapatite; Osteoblast; Osteoclast; Strontium