Basic fibroblast growth factor suppresses tropoelastin gene expression in cultured human periodontal fibroblasts

Growth factors are known to play a major role in the regeneration of the pe riodontium. Basic fibroblast growth factor (bFGF) is a polypeptide growth f actor considered to have a role in chemotaxis and mitogenesis of periodonta l ligament (PDL) cells. The aim of this study was to assess the effect of b FGF on the transcription level of tropoelastin. As known controls, we asses sed the transcription levels of collagen type I, collagen type III and the housekeeping gene, actin. Initially, PDL cells were cultured without bFGF f or 3, 7 and 14 days. At each time point, total RNA was extracted and the le vels of transcription were assessed by semiquantitative reverse transcripti on polymerase chain reaction (RT-PCR) assay. The results showed that tropoe lastin mRNA is transcribed in PDL cells and its levels increased from minim al amounts by day 3 to maximal amounts by day 14 of culture. We further exa mined the effect of the addition of 10 ng/ml bFGF to the culture media by d ay 14. The results showed that the addition of bFGF suppressed the transcri ption level of tropoelastin. At that time, as expected, a decrease in colla gen type I transcription level was shown, while the transcription level of collagen type III was not affected. The findings that elastin is transcribe d ill vitro by PDL cells, but only negligibly in vivo, imply mechanisms tha t downregulate or even shut down the expression of the elastin gene in the functioning PDL. Basic FGF might be one of the cytokines involved in contro l of elastin expression ill vivo.