title: Novel low temperature setting nanocrystalline calcium phosphate cements for bone repair: osteoblast cellular response and gene expression studies.
abstract: Low temperature setting calcium phosphate cements (CPC) formed from reactive calcium phosphate precursors are receiving great attention in the fields of orthopaedics and tissue engineering. The purpose of this study was to evaluate the mechanical properties and osteocompatibility of a novel calcium deficient hydroxyapatite (CDSHA) with a Ca/P ratio of 1.6 developed in our laboratories and compare it to a previously developed calcium deficient hydroxyapatite (CDHA) with a Ca/P ratio of 1.5. The results demonstrated that the calcium-deficient hydroxyapatites (HA) formed from the CPCs were similar to biological HA at physiological temperature and the elastic moduli of CDHA and CDSHA were found to be 174.42 +/- 20.41 MPa (p < 0.05) and 115.86 +/- 24.8 MPa (p < 0.05), respectively. The surface morphologies of the two calcium deficient HA's formed were identical with a micro/nano porous structure as evidenced from SEM. The cellular proliferation on CDHA, and CDSHA, was comparable to the control, tissue culture polystyrene (TCPS) (p < 0.05). Alkaline phosphatase activity was significantly elevated on CDHA and CDSHA matrices at early time points when compared with the control (TCPS) (p < 0.05). Osteoblast cells gene expression on CDHA, and CDSHA showed type I collagen, alkaline phosphatase, osteocalcin, and osteopontin activity at both 7 and 14 days of culture. Thus, novel calcium-deficient HAs, CDHA, and CDSHA formed at low temperature are promising candidates for orthopaedic applications based on their ability to promote osteoblast cell adhesion and gene expression in vitro.
authors.affiliation: Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Swaminathan
authors.initials: S
authors.lastname: Sethuraman
authors.forename: Lakshmi S
authors.initials: LS
authors.lastname: Nair
authors.forename: Saadiq
authors.initials: S
authors.lastname: El-Amin
authors.forename: My-Tien N
authors.initials: MT
authors.lastname: Nguyen
authors.forename: Yaser E
authors.initials: YE
authors.lastname: Greish
authors.forename: Jared D
authors.initials: JD
authors.lastname: Bender
authors.forename: Paul W
authors.initials: PW
authors.lastname: Brown
authors.forename: Harry R
authors.initials: HR
authors.lastname: Allcock
authors.forename: Cato T
authors.initials: CT
authors.lastname: Laurencin
mesh_terms: D016475:3T3 Cells; D000469:Alkaline Phosphatase / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D001843:Bone Cements / Q000737:chemistry; D002130:Calcium Phosphates / Q000737:chemistry; D002448:Cell Adhesion; D024042:Collagen Type I / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D017886:Durapatite / Q000737:chemistry; D015870:Gene Expression; D008422:Materials Testing; D051379:Mice; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism*; D015675:Osteocalcin / Q000235:genetics; D053495:Osteopontin / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013499:Surface Properties; D013696:Temperature; D023822:Tissue Engineering
chemical_list: D001843:Bone Cements; D002130:Calcium Phosphates; D024042:Collagen Type I; D017931:DNA Primers; C506896:Spp1 protein, mouse; D015675:Osteocalcin; D053495:Osteopontin; D017886:Durapatite; C020243:calcium phosphate; D000469:Alkaline Phosphatase