Dexamethasone and Basic‐Fibroblast Growth Factor Regulate Markers of Mineralization in Cementoblasts In Vitro

Background: The aim of this study was to determine the effects of basic‐fibroblast growth factor (b‐FGF) and/or dexamethasone (Dex) on cementoblasts in vitro. Methods: Murine cementoblasts were treated as follows: 1) 5% FBS (fetal bovine serum) + ascorbic acid (AA, 50 µg/ml, control); 2) 5% FBS+Dex (10–7M)+AA; 3) 5% FBS+b‐FGF (50 ng/ml)+AA; or 4) 5% FBS+Dex (10 –7 M)+b‐FGF (50 ng/ml)+AA and then evaluated by Northern analysis for changes in specific genes and by von Kossa stain for changes in mineral nodule formation. Results: Mitotic activity: b‐FGF stimulated DNA synthesis significantly versus negative control. Gene expression: osteocalcin (OCN): Dex or b‐FGF or the combination resulted in a decrease in expression versus control. Bone sialoprotein (BSP): Dex increased expression of BSP mRNA levels, b‐FGF decreased transcript for BSP at 6 and 24 hours. Long‐term (8 days) Dex, b‐FGF, or Dex plus b‐FGF caused a decrease in BSP expression versus control; osteopontin (OPN): both Dex and b‐FGF increased transcripts for OPN seen by 6 hours, with a greater increase noted with b‐FGF versus Dex. No apparent additive effect of Dex with b‐FGF was noted; matrix gamma‐carboxyglutamic acid protein (MGP): b‐FGF induced transcripts for MGP and addition of Dex increased this effect, while Dex alone had no effect on expression. Biomineralization: Dex increased cementoblast‐ mediated biomineralization, while b‐FGF blocked this activity, and addition of Dex to b‐FGF did not alter FGF associated inhibition. Conclusion: Dex and FGF alone and in combination alter cementoblast behavior, but additional studies are required to determine whether these factors have beneficial effects at the clinical level. J Periodontol 2005;76:1550‐1558 .