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Background and Objective: The epithelial rests of Malassez (ERM) are developmental residues of Hertwig's epithelial root sheath, and they are present throughout life in the periodontal ligament. Previous studies have shown that ERM induce cementogenesis or inhibit cement-osteogenesis. This study investigated how ERM cells are involved in osteoblast mineralization in an in vitro coculture system., Materials and Methods: ERM cells were isolated from porcine periodontal ligament by an outgrowth method. Osteoblast-like MC3T3-E1 cells were cocultured with ERM or gingival epithelium (GE) cells in six-well Transwell units. Mineralization of MC3T3-E1 cells was confirmed by Alizarin Red staining after 30 days of culture. Alkaline phosphatase (ALP) activity was measured in the culture media. To examine whether enamel matrix proteins are involved in the mineralization of MC3T3-E1 cells, an anti-amelogenin antibody was added to the culture media., Results: The staining by Alizarin Red of MC3T3-E1 cells cocultured with ERM cells was clearly weaker than that in the GE cell coculture. The ALP activity in the ERM cell coculture was significantly lower than that in the GE cell coculture (p < 0.05). Alizarin Red staining of MC3T3-E1 cells in the ERM cell coculture with anti-amelogenin antibody was clearly stronger than in those cocultures without the antibody at 30 days. The ALP activity in the ERM cell coculture with anti-amelogenin antibody was significantly higher than in those cultures without the antibody (p < 0.05)., Conclusion: This study demonstrated that ERM cells inhibit the calcification of osteoblast-like cells in a Transwell coculture system and that this inhibition is reversed with an anti-amelogenin antibody., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Objective: Drosomycin-like defensin (DLD) is a recently discovered antimicrobial peptide mainly active against filamentous fungi. The present study investigated the expression profile of DLD in oral epithelium and oral squamous cell carcinoma (SCC) cell lines., Methods: Tissue sections of human oral mucosa, keratinocytes derived from oral mucosa (NOK) and eight kinds of SCC cell lines were used. In situ hybridization was performed on tissue sections of oral mucosa. Expression levels of DLD in the cells were observed by reverse transcription polymerase chain reaction (RT-PCR) and real-time RT-PCR assays. The cells were treated with IL-1β, IL-8 and TNF-α, and agonists for TLR2, TLR4 and β-glucan. DLD expression in cells was increased and decreased by the DLD gene and its siRNA transfection, respectively. The proliferation rates were assessed by cell counting., Results: By means of in situ hybridization, DLD mRNA positive staining was detected in the epithelial layer of the oral mucosa. An RT-PCR assay confirmed the expression of DLD mRNA in keratinocytes derived from oral epithelium. Expression of DLD in two out of eight cell lines was significantly lower than in NOK cells. The expression levels of DLD mRNA were not significantly changed in the cells stimulated with any cytokines or agonists. The cell proliferation rate where there was decreased expression of DLD was significantly lower than in the control., Conclusion: DLD may be partially involved in the defence against filamentous fungal infection in the oral mucosa, and may also serve other functions, such as contribution to cell growth., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Objective: It is unknown which genes are differentially expressed in cultured epithelial cells derived from the epithelial rests of Malassez (ERM) in periodontal ligament and oral gingival epithelium (OGE). This study analysed the different gene expression of OGE and ERM cells using a DNA microarray technique., Design: Epithelial cells from ERM and OGE were isolated from porcine periodontal ligament and oral gingival epithelium. Each RNA sample extracted from the cells was reverse transcribed into cDNA and labelled with either cytidine 5-dUTP (Cy5) or cytidine 3-dUTP (Cy3). These labelled cDNA probes were then mixed and simultaneously hybridised to the Pig 13K microarray plate bearing 13,295 different genes (Operon, AL). Cellular enzyme-linked immunosorbent assay (CELISA) was performed to confirm the expression at protein level., Results: There were nine genes common to the triplicate microarrays in ERM cells and one in OGE cells. Four of the nine genes including tissue factor (TF), FAT cadherin (FAT) and two unknown genes were expressed at levels more than threefold higher in ERM cells than in OGE cells. The protein levels of both TF and FAT in ERM cells were significantly higher than those in OGE., Conclusion: TF and FAT may act as markers to distinguish ERM cells from OGE cells in vitro.