title: Putative stem cells in regenerating human periodontium.
abstract: OBJECTIVE
  Human postnatal stem cells have been identified in periodontal ligament, with the potential to regenerate the periodontium in vivo. However, it is unclear if periodontal ligament stem cells are present in regenerating periodontal tissues. The aim of this study was to identify and localize putative stem cells in block biopsies and explant cultures of regenerating human periodontal tissues.
  
  
  METHODS
  Guided tissue regeneration was carried out on the molars of three human volunteers. After 6 wk, the teeth with the surrounding regenerating tissues and bone were surgically removed and processed for immunohistochemistry. The mesenchymal stem cell-associated markers STRO-1, CD146 and CD44 were used to identify putative stem cells. Cell cultures established from regenerating tissue explants were analysed by flow cytometry to assess the expression of these markers. Mineralization, calcium concentration and adipogenic potential of regenerating tissue cells were assessed and compared with periodontal ligament stem cells, bone marrow stromal stem cells and gingival fibroblasts.
  
  
  RESULTS
  STRO-1(+), CD44(+) and CD146(+) cells were identified in the regenerating tissues. They were found mainly in the paravascular and extravascular regions. Flow cytometry revealed that cultured regenerating tissue cells expressed all three mesenchymal stem cell associated markers. The regenerating tissue cells were able to form mineral deposits and lipid-containing adipocytes. However, the level of mineralization in these cells was lower than that of periodontal ligament stem cells and bone marrow stromal stem cells.
  
  
  CONCLUSIONS
  Cells with characteristics of putative mesenchymal stem cells were found in regenerating periodontal tissues, implying their involvement in periodontal regeneration.
authors.affiliation: School of Dentistry, University of Adelaide, Adelaide, SA, Australia.
authors.forename: N-H
authors.initials: NH
authors.lastname: Lin
authors.forename: D
authors.initials: D
authors.lastname: Menicanin
authors.forename: K
authors.initials: K
authors.lastname: Mrozik
authors.forename: S
authors.initials: S
authors.lastname: Gronthos
authors.forename: P M
authors.initials: PM
authors.lastname: Bartold
mesh_terms: D017667:Adipocytes; D000328:Adult; D053687:Adult Stem Cells / Q000502:physiology*; D000369:Aged, 80 and over; D000954:Antigens, Surface / Q000032:analysis; D001854:Bone Marrow Cells / Q000502:physiology; D051929:CD146 Antigen / Q000032:analysis; D002454:Cell Differentiation; D002478:Cells, Cultured; D005260:Female; D005434:Flow Cytometry; D016557:Guided Tissue Regeneration, Periodontal; D006801:Humans; D018960:Hyaluronan Receptors / Q000032:analysis; D007150:Immunohistochemistry; D008297:Male; D059630:Mesenchymal Stem Cells / Q000502:physiology*; D010006:Osteoblasts; D010513:Periodontal Ligament / Q000166:cytology*; D010519:Periodontium / Q000502:physiology*; D012038:Regeneration / Q000502:physiology*; D017154:Stromal Cells / Q000502:physiology; D055815:Young Adult
chemical_list: D000954:Antigens, Surface; D051929:CD146 Antigen; C497483:CD44 protein, human; D018960:Hyaluronan Receptors; C497902:MCAM protein, human; C525591:STRO-1 antigen, human