Fibroblast growth factor 2 stimulates differentiation of mechanically-stressed human periodontal ligament fibroblasts into cementoblasts.

Abstract

Introduction: Orthodontic treatment enables tooth movement through bone remodeling. The effects of fibroblast growth factor 2 (FGF2) on human periodontal ligament fibroblasts (HPdLFs) in response to mechanical stimulation that occurs during orthodontic treatment remain unexplained. We investigated the effects of FGF2 and mechanical stress on HPdLF differentiation, focusing on cementoblast differentiation.

Methods: The effects of FGF2 and mechanical stress (applied for 24 hours using a centrifuge) on HPdLFs were evaluated. Changes in marker levels were assessed using real-time reverse transcriptase-polymerase chain reaction and western blotting. Furthermore, the effect of FGF2 treatment on HPdLF mineralization was assessed after 3 and 5 weeks using Alizarin red S staining (BMK-R009: Bio Future Technologies, Tokyo, Japan).

Results: Treatment of HPdLFs with 20 ng/mL FGF2 increased the expression of CEMP1 and RUNX2 but did not significantly alter the expression of FGF2, FGFR1, and FGFR2. In HPdLFs exposed to mechanical stress, expression of FGFR1 and OCN was increased, whereas that of FGF2, CEMP1, CAP, GLUT1, ALP, and OPN was reduced considerably. Treatment of mechanically-stressed HPdLFs with FGF2 did not change FGF2 expression, but expression of FGFR1, CEMP1, CAP, and GLUT1 increased significantly. In addition, FGFR1 was significantly upregulated at the protein level, whereas cementoblast differentiation markers showed an upward trend. Mineralization showed no changes at 3 weeks. However, at 5 weeks, considerable mineralization was observed in mechanically-stressed cells continuously exposed to FGF2.

Conclusions: Mechanical stress increases FGFR1 expression in HPdLFs. FGF2 promotes the differentiation of mechanical-stressed HPdLFs into cementoblasts and their mineralization.