title: Effects of enamel matrix derivative on bone-related mRNA expression in human periodontal ligament cells in vitro.
abstract: BACKGROUND
  Enamel matrix derivative (EMD) has demonstrated the potential to stimulate periodontal regeneration with mineralized tissue formation. Molecular regulators of bone metabolism include osteoprotegrin (OPG), receptor activator of nuclear factor kappa B ligand (RANKL), cyclooxygenase 2 (COX2), and core binding factor alpha 1 (Cbfa1). The role of these regulatory molecules within the context of EMD stimulation of mineralized tissue formation is unknown. Therefore, the purpose of this investigation was to explore the effects of EMD on these bone-related molecules in human periodontal ligament (PDL) cells.
  
  
  METHODS
  Human PDL-cell cultures were treated with EMD (5 to 100 microg/ml) for 24 hours. Total RNA was isolated using phenolchloroform, and reverse transcription-polymerase chain reaction (RT-PCR) was performed using primers specific for OPG, RANKL, COX2, Cbfa1, and aldolase, with amplification in the exponential range for each molecule studied.
  
  
  RESULTS
  The results of this study show that there is a significant (P <0.05) increase in COX2 mRNA levels with EMD treatment, and no effects were noted on mRNA levels for Cbfa1. RANKL mRNA levels were significantly decreased (P <0.01) up to 50% with EMD treatment > or =25 microg/ml. OPG levels showed minimal effects with EMD treatment. However, the RANKL/OPG ratio showed a 40% to 55% reduction with EMD >or =25 microg/ml.
  
  
  CONCLUSIONS
  This study supports a role for EMD stimulation of mineralized tissue formation consistent with periodontal regeneration by modulating regulatory molecules critical to bone metabolism at the RNA level.
authors: Department of Periodontology, School of Dentistry at Tokyo, Nippon Dental University, Tokyo, Japan.
authors: Kazuaki
authors: K
authors: Takayanagi
authors: Ginko
authors: G
authors: Osawa
authors: Hiroshi
authors: H
authors: Nakaya
authors: David L
authors: DL
authors: Cochran
authors: Kyuich
authors: K
authors: Kamoi
authors: Thomas W
authors: TW
authors: Oates