Impact of FGF1 on human periodontal ligament fibroblast growth, osteogenic differentiation and inflammatory reaction in vitro.

Abstract

To investigate in vitro the impact of fibroblast growth factor1 (FGF1) in comparison to ascorbic acid (AscA) on human periodontal ligament fibroblast (HPdLF) growth, their osteogenic differentiation, and modulation of their inflammatory reaction to mechanical stress. The influence of different concentrations of FGF1 (12.5-200 ng/mL) on growth and proliferation of HPdLF cells was analyzed over 20days by counting cell numbers and the percentage of Ki67-positive cells. Quantitative expression analysis of genes encoding the osteogenic markers alkaline phosphatase (ALPL), Runt-related transcription factor2 (RUNX2), osteocalcin (OCN), and osteopontin (OSP), as well as the fibroblast markers vimentin (VIM) and fibroblast-specific protein1 (FSP1), was performed after 2and 20days of cultivation. Metabolic activity was determined by MTT assay. For comparison with AscA, 50 ng/mL FGF1 was used for stimulation for 2and 20days. Cell number, percentage of Ki67-positive cells, and expression of osteoblast- and fibroblast-specific genes were examined. Alkaline phosphatase activity was visualized by NBT/BCIP and calcium deposits were stained with alizarin red. Cytokine (IL‑6, IL‑8, COX2/PGE2) expression and secretion were analyzed by qPCR and ELISA in 6 h mechanically compressed HPdLF cultured for 2days with FGF1 or ascorbic acid. Higher concentrations of FGF1 promoted cell proliferation upon short-term stimulation, whereas prolonged treatment induced the expression of osteogenic markers even with low concentrations. AscA promotes cell growth more markedly than FGF1 in short-term cultures, whereas FGF1 induced osteogenic cell fate more strongly in long-term culture. Both factors induced an increased inflammatory response of HPdLF to mechanical compression. Our data suggest that FGF1 promotes an osteogenic phenotype of HPdLF and limits inflammatory response to mechanical forces compared to AscA.