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 4þ (from Na 2 SiO 3 ) and Ca 2þ (from CaCl 2 :H 2 O) ion treatments both individually (0.4 mM each þ control treatment) and combinatorially (0.4 mM Si 4þ þ 0.4 mM Ca 2þ þ control treatment) and compared to control treated (a-minimum essential medium, 10% fetal bovine serum, and 1% penicillinstreptomycin) 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)a1/Col(I)a2), core-binding factor a (cbfa1/Runx2), and osteocalcin (OCN), which indicated osteoblast progenitor differentiation into a mineralizing phenotype. . These results support the larger concept that ions (possibly released from bioactive glasses) could control bone formation by targeting osteoblast marker expression.

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This study tests the hypothesis that silicon and calcium ions combinatorially target gene expression during osteoblast differentiation. MC3T3‐E1 subclone 4 osteoblast progenitors were exposed to elevated Si4+ (Na2SiO3) and Ca2+ (CaCl2) ion treatments both individually (50 ppm) and combinatorially (50 ppm Si + 50 ppm Ca) above control media conditions (α‐MEM, 10% FBS, 1% pen‐strep). Cell density significantly increased with time (5 days), but no significant difference was observed between treatments. All treatments were additionally supplemented with ascorbic acid (AA, 50 ppm) to induce differentiation. Relative expression of collagen type 1 (Col1α1, day 1), core‐binding factor a (cbfa1 or Runx2, day 6), and osteocalcin (OCN, day 6) was studied based on the timeline of osteoblast differentiation. Increased Si or Ca ion treatments enhanced Col1α1, Runx2, and OCN expression. Increased Si + Ca ion treatments enhanced OCN expression alone with no affect on Col1α1 and suppression of Runx2 (no amplification). Collagen fiber bundles were dense and elongated, for extracellular matrices (ECM) exposed to Si ions as compared to other treatments. These results indicated that individual ions enhanced multiple osteogenic gene expression while combined ion treatments enhanced individual gene expression.Grant Funding Source : NIH/NIDCR #5P30DE020742‐02