In vitro characterization of the cytokine profile of the epithelial cell rests of malassez

Background: The epithelial cell rests of Malassez (ERM) are an integral part of the periodontal ligament and are considered to play an important role in dental pathology. Surprisingly, this cell type is poorly described and is often disregarded in the context of periodontal research. The aim of this study was to establish primary cell cultures of human ERM, characterize the cytokine profile, and compare it to other periodontal cell entities. Methods: ERM-derived epithelial cells were isolated from the periodontal ligament of three subjects. A cytokine antibody array, including 120 cytokines in two membranes, was used to determine the cytokine profile of conditioned medium from the ERM-derived epithelial cells. The results were compared to those of gingival epithelial cells and periodontal ligament fibroblasts. Results: ERM-derived epithelial cells expressed 29 of 120 cytokines in significant amounts, including cytokines, chemokines, growth factors, and related proteins, such as interleukin (IL)-1, -6, -8, and -10; granulocyte macrophage-colony stimulating factor; monocyte chemoattractant protein (MCP)- 1, -2, and -3; amphiregulin; glial-derived neurotrophic factor; vascular endothelial growth factor; and insulin-like growth factor binding protein-2. The cytokine profile of ERM cells was similar to that of gingival epithelial cells but strikingly different from the profile of periodontal ligament fibroblasts. Conclusions: The results indicated that, via paracrine secretion of a variety of soluble factors, the ERM cells actively take part in the homeostasis of the periodontium. Therefore, future research on the pathophysiology of periodontal tissue should include this often overlooked cell type.