title: Interaction of enamel matrix proteins with human periodontal ligament cells.
abstract: OBJECTIVE
  It has recently been shown that enamel matrix derivative (EMD) components (Fraction C, containing <6 kDa peptides (mainly a 5.3 kDa tyrosine-rich amelogenin peptide (TRAP)), and Fraction A, containing a mixture of >6 kDa peptides (including a leucine-rich amelogenin peptide (LRAP))) differentially regulate osteogenic differentiation of periodontal ligament (PDL) cells. The present study examined whether EMD and the EMD Fractions (i) bind and internalize into PDL cells and (ii) precipitate and form insoluble complexes on PDL cells.
  
  
  METHODS
  Biotin-labelled EMD/EMD Fractions were incubated with PDL cells under various different culture conditions and confocal and electron microscopies were carried out to examine the binding and intracellular trafficking of these proteins.
  
  
  RESULTS
  The results reported here show, for the first time, that at least some components in Fraction A and the TRAP peptide in Fraction C can bind and be internalized by human PDL cells via receptor-mediated endocytosis. In addition, Fraction A was found to form insoluble aggregate-like structures on PDL cells, whereas Fraction C was soluble in culture media.
  
  
  CONCLUSIONS
  Soluble amelogenin isoform TRAP appears to be internalizing into a subset of PDL cells. Moreover, TRAP uptake is most likely controlled by receptor-mediated endocytosis.
  
  
  CONCLUSIONS
  Information on interaction between PDL cells and EMD/TRAP might prove useful in designing targeted interventions (i.e. use of chemically prepared soluble amelogenin peptides) to repair/regenerate periodontal tissues. Such interventions can also (i) avoid the use of rather crude animal-derived enamel matrix protein (EMP)/EMD preparation and (ii) preparation of cost-effective and more controlled chemically synthesized amelogenin peptides for the clinical use.
authors.affiliation: Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK.|Periodontology Unit, UCL Eastman Dental Institute, University College London, London, UK.
authors.forename: Harsh D
authors.initials: HD
authors.lastname: Amin
authors.affiliation: Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK. i.olsen@ucl.ac.uk.
authors.forename: Irwin
authors.initials: I
authors.lastname: Olsen
authors.affiliation: Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK.|Department of Nanobiomedical Science & BK21 Plus NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan, 330-714, Republic of Korea.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Knowles
authors.affiliation: Department of Periodontology and Implant Dentistry, New York University, College of Dentistry, New York, USA.
authors.forename: Michel
authors.initials: M
authors.lastname: Dard
authors.affiliation: Periodontology Unit, UCL Eastman Dental Institute, University College London, London, UK. n.donos@ucl.ac.uk.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Donos
mesh_terms: D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D003746:Dental Enamel Proteins / Q000494:pharmacology*; D006801:Humans; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D010012:Osteogenesis / Q000187:drug effects*; D010513:Periodontal Ligament / Q000166:cytology*; D013194:Staining and Labeling
chemical_list: D003746:Dental Enamel Proteins; C109069:enamel matrix proteins
keywords: EMD; EMD uptake; Intracellular trafficking; Periodontal ligament cells; Receptor-mediated endocytosis