Gene expression profiles of periodontal ligament cells treated with enamel matrix proteins in vitro: Analysis using cDNA arrays

Abstract

Background: A number of procedures have been used to achieve periodontal regeneration. Recently, enamel matrix derivative (EMD) has been the subject of significant basic and clinical investigations. The precise molecular events involved in EMD modulation of periodontal wound healing are not completely under stood; however, cDNA microarray technology may enable rapid and accurate examination of EMD-mediated changes in gene expression in periodontal ligament (PDL) cells in vitro. The present study was undertaken to explore the selective effects of EMD on the activities of 268 cytokine, growth factor, and receptor genes in PDL. Methods: PDL cells were cultured in the absence and presence of EMD at a concentration of 100 μg/ml for 4 days. RNA was extracted and used to generate labeled cDNA probes. These were hybridized to cDNA arrays comprising 268 genes and exposed to x-ray films. Autoradiographs were digitized and analyzed. Results: Forty-six percent (125 of 268) of the tested genes were found to be expressed by the PDL cells. Of these 125 genes, 38 were differentially expressed by PDL cells which had been cultured in the presence of EMD. Among the 38, 12 were found to be downregulated, notably mostly inflammatory genes, whereas 26 genes demonstrated upregulation, many of these coding for growth factors and growth factor receptors. Conclusions: The present study has shown that EMD downregulates the expression of genes involved in the early inflammatory phases of wound healing while simultaneously upregulating genes encoding growth and repair-promoting molecules. This may partly explain the apparent efficacy of EMD application in periodontal regeneration.