Si and Ca individually and combinatorially target enhanced MC3T3-E1 subclone 4 early osteogenic marker expression.
This study tests the hypothesis that silicon and calcium ions combinatorially target gene expression during osteoblast differentiation. MC3T3-E1 subclone 4 osteoblast progenitors (transformed mouse calvarial osteoblasts) were exposed to Si(4+) (from Na(2)SiO(3)) and Ca(2+) (from CaCl(2):H(2)O) ion treatments both individually (0.4 mM each + control treatment) and combinatorially (0.4 mM Si(4+) + 0.4 mM Ca(2+) + control treatment) and compared to control treated (α-minimum essential medium, 10% fetal bovine serum, and 1% penicillin-streptomycin) cells. Cell proliferation studies showed no significant increase in cell density between treatments over 5 days of culture. Cellular differentiation studies involved addition of ascorbic acid (50 mg/L) for all treatments. Relative gene expression was determined for collagen type 1 (Col(I)α1/Col(I)α2), core-binding factor a (cbfa1/Runx2), and osteocalcin (OCN), which indicated osteoblast progenitor differentiation into a mineralizing phenotype. Increased Si(4+) or Ca(2+) ion treatments enhanced Col(I)α1, Col(I)α2, Runx2, and OCN expression, while increased Si(4+) + Ca(2+) ion treatments enhanced OCN expression. Moreover, it was found that a Si(4+)/Ca(2+) ratio of unity was optimal for maximal expression of OCN. Collagen fiber bundles were dense, elongated, and thick within extracellular matrices (ECM) exposed to Si(4+) and Si(4+) + Ca(2+) treatments, while collagen fiber bundles were sparse, short, and thin within Ca(2+) and control treated ECM. These results indicated that individual ions enhance multiple osteogenic gene expression, while combined ion treatments enhance individual gene expression. In addition, these results indicated that Si(4+) enhanced osteoblast gene expression and ECM formation at higher levels than Ca(2+). These results support the larger concept that ions (possibly released from bioactive glasses) could control bone formation by targeting osteoblast marker expression.
Department of Biomedical Sciences, Texas A&M Health Science Center, Baylor College of Dentistry, Dallas, TX, USA. venu.varanasi@ucsf.edu
Venu G
VG
Varanasi
Kelly K
KK
Leong
Lisa M
LM
Dominia
Stephanie M
SM
Jue
Peter M
PM
Loomer
Grayson W
GW
Marshall
D016475:3T3 Cells; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001205:Ascorbic Acid / Q000494:pharmacology; D002118:Calcium / Q000008:administration & dosage / Q000494:pharmacology*; D002452:Cell Count; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D024042:Collagen Type I / Q000032:analysis; D000090602:Collagen Type I, alpha 1 Chain; D050659:Core Binding Factor Alpha 1 Subunit / Q000032:analysis; D004338:Drug Combinations; D005109:Extracellular Matrix / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects*; D015675:Osteocalcin / Q000032:analysis; D010012:Osteogenesis / Q000187:drug effects*; D016133:Polymerase Chain Reaction; D012825:Silicon / Q000008:administration & dosage / Q000494:pharmacology*; D013234:Stem Cells / Q000187:drug effects*; D013997:Time Factors
D000975:Antioxidants; D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D050659:Core Binding Factor Alpha 1 Subunit; D004338:Drug Combinations; C493716:Runx2 protein, mouse; D015675:Osteocalcin; D001205:Ascorbic Acid; D002118:Calcium; D012825:Silicon