title: Enhanced osteocalcin expression by osteoblast-like cells (MC3T3-E1) exposed to bioactive coating glass (SiO2-CaO-P2O5-MgO-K2O-Na2O system) ions.
abstract: This study tested the hypothesis that bioactive coating glass (SiO(2)-CaO-P(2)O(5)-MgO-K(2)O-Na(2)O system), used for implant coatings, enhanced the induction of collagen type 1 synthesis and in turn enhanced the expression of downstream markers alkaline phosphatase, Runx2 and osteocalcin during osteoblast differentiation. The ions from experimental bioactive glass (6P53-b) and commercial Bioglass(TM) (45S5) were added to osteoblast-like MC3T3-E1 subclone 4 cultures as a supplemented ion extract (glass conditioned medium (GCM)). Ion extracts contained significantly higher concentrations of Si and Ca (Si, 47.9+/-10.4 ppm; Ca, 69.8+/-14.0 for 45S5; Si, 33.4+/-3.8 ppm; Ca, 57.1+/-2.8 ppm for 6P53-b) compared with the control extract (Si<0.1 ppm, Ca 49.0 ppm in alpha-MEM) (ANOVA, p<0.05). Cell proliferation rate was enhanced (1.5x control) within the first 3 days after adding 45S5 and 6P53-b GCM. MC3T3-E1 subclone 4 cultures were then studied for their response to the addition of test media (GCM and control medium along with ascorbic acid (AA; 50 ppm)). Each GCM+AA treatment enhanced collagen type 1 synthesis as observed in both gene expression results (day 1, Col1alpha1, 45S5 GCM+AA: 3x control+AA; 6P53-b GCM+AA: 4x control+AA; day 5, Col1alpha2, 45S5 GCM+AA: 3.15x control+AA; 6P53-b GCM+AA: 2.35x control+AA) and in histological studies (Picrosirius stain) throughout the time course of early differentiation. Continued addition of each GCM and AA treatment led to enhanced expression of alkaline phosphatase (1.4x control+AA after 5 days, 2x control+AA after 10 days), Runx2 (2x control+AA after 7 days) and osteocalcin gene (day 3, 45S5 GCM+AA: 14x control+AA; day 5, 6P53-b GCM+AA: 19x control+AA) and protein expression (40x-70x control+AA after 6 days). These results indicated the enhanced effect of bioactive glass ions on key osteogenic markers important for the bone healing process.
authors.affiliation: Division of Biomaterials and Bioengineering, University of California, San Francisco, CA 94143-0758, USA. venu.varanasi@ucsf.edu
authors.forename: V G
authors.initials: VG
authors.lastname: Varanasi
authors.forename: E
authors.initials: E
authors.lastname: Saiz
authors.forename: P M
authors.initials: PM
authors.lastname: Loomer
authors.forename: B
authors.initials: B
authors.lastname: Ancheta
authors.forename: N
authors.initials: N
authors.lastname: Uritani
authors.forename: S P
authors.initials: SP
authors.lastname: Ho
authors.forename: A P
authors.initials: AP
authors.lastname: Tomsia
authors.forename: S J
authors.initials: SJ
authors.lastname: Marshall
authors.forename: G W
authors.initials: GW
authors.lastname: Marshall
mesh_terms: D016475:3T3 Cells; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation; D049109:Cell Proliferation; D002516:Ceramics / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism; D017077:Culture Media, Conditioned / Q000737:chemistry / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D015870:Gene Expression; D005898:Glass; D007477:Ions / Q000737:chemistry*; D008422:Materials Testing; D008670:Metals / Q000737:chemistry*; D051379:Mice; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology*; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism*; D010087:Oxides / Q000737:chemistry*
chemical_list: D015415:Biomarkers; D020099:Coated Materials, Biocompatible; D050659:Core Binding Factor Alpha 1 Subunit; D017077:Culture Media, Conditioned; D007477:Ions; D008670:Metals; D010087:Oxides; C425330:bioactive glass 45S5; D015675:Osteocalcin