title: Production of osteopontin by cultured porcine epithelial cell rests of Malassez.
abstract: BACKGROUND
  The epithelial cell rests of Malassez (ERM) are derived from Hertwig's epithelial root sheath (HERS). During development the cells of HERS deposit a variety of molecules on the newly forming root surface. The possibility that ERM retain this potential after root development is completed and secrete bone or cementum-related proteins needs to be investigated. The purpose of this study was to determine the expression of the non-collagenous proteins osteopontin (OPN) and bone sialoprotein (BSP) by cells derived from the epithelial cell rests of porcine periodontium.
  
  
  METHODS
  ERM and fibroblasts were cultured from porcine periodontal ligament. The cells were identified and characterized using transmission electron microscopy, immunohistochemistry, western blot analysis of proteins, reverse transcription-polymerase chain reaction and ability to form mineralized nodules in culture. In particular the expression of the mineralized tissue-related proteins, BSP and OPN, was studied.
  
  
  RESULTS
  Cells from porcine periodontal ligaments were successfully cultured; separated and characterized as being of either an epithelial or fibroblastic phenotype. Although the ERM did not form mineralized nodules in culture, they did express a significant amount of mRNA for OPN.
  
  
  CONCLUSIONS
  The results from this study provide evidence that ERM express mRNA for at least one bone/cementum-related protein. Whether this function would be consistent with a role for ERM in tissue formation, inflammation and regeneration remains to be established.
authors.affiliation: Department of Dentistry, University of Queensland, Brisbane, Australia.
authors.forename: Julio C
authors.initials: JC
authors.lastname: Rincon
authors.forename: Yin
authors.initials: Y
authors.lastname: Xiao
authors.forename: William G
authors.initials: WG
authors.lastname: Young
authors.forename: P Mark
authors.initials: PM
authors.lastname: Bartold
mesh_terms: D000539:Alveolar Process / Q000166:cytology / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D004658:Enamel Organ / Q000166:cytology; D004847:Epithelial Cells / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D005881:Gingiva / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D058574:Integrin-Binding Sialoprotein; D007633:Keratins / Q000032:analysis; D046529:Microscopy, Electron, Transmission; D053495:Osteopontin; D010513:Periodontal Ligament / Q000166:cytology / Q000378:metabolism*; D010641:Phenotype; D010750:Phosphoproteins / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012795:Sialoglycoproteins / Q000096:biosynthesis*; D013552:Swine; D014092:Tooth Root / Q000166:cytology
chemical_list: D058574:Integrin-Binding Sialoprotein; D010750:Phosphoproteins; D012795:Sialoglycoproteins; D053495:Osteopontin; D007633:Keratins