title: Periodontal ligament stem cells possess the characteristics of pericytes.
abstract: BACKGROUND
  Periodontal ligament (PDL) contributes to maintaining homeostasis in periodontal tissues by supplying stem/progenitor cells. It has long been suggested that PDL stem cells/progenitors are located around blood vessels. Recently mesenchymal stem cells (MSCs) have been isolated and cultured from PDL in vitro, although the location of the stem cells in PDL is unclear. The purpose of this study is to test the characteristics of human PDL stem cells (PDLSCs) and examine their similarity to related vascular cell types, such as pericytes and endothelial cells.
  
  
  METHODS
  PDLSCs were obtained from healthy extracted teeth using the collagenase/dispase enzyme digestion method. MSC and pericyte characteristics of PDLSCs were examined by cell surface marker expression using flow cytometry. The expression of pericyte markers was tested using immunohistochemistry. Pericyte-like functions of PDLSCs were examined in co-culture of PDLSCs and umbilical vein endothelial cells on a gel matrix.
  
  
  RESULTS
  Cultured PDLSCs were positive for both MSC markers and pericyte markers, including cluster of differentiation 146 (CD146), neural/glial antigen 2 (NG2), and CD140b. When pericyte marker expression was explored in rat periodontal tissue sections, CD146- and NG2-positive signals were observed in the perivascular area of the PDL. Further, when the cells were cultured with human umbilical cord endothelial cells under conditions for forming capillary-like structures in vitro, PDLSCs localized adjacent to endothelial cells and contributed to the stability of the capillary-like structure.
  
  
  CONCLUSIONS
  PDLSCs possess pericyte-like characteristics and may localize as pericytes in the PDL. These data provide useful information for stem cell biology in periodontal research and stem cell-based periodontal therapy.
authors.affiliation: Department of Nanomedicine, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Kengo
authors.initials: K
authors.lastname: Iwasaki
authors.forename: Motohiro
authors.initials: M
authors.lastname: Komaki
authors.forename: Naoki
authors.initials: N
authors.lastname: Yokoyama
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Atsuko
authors.initials: A
authors.lastname: Taki
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Kimura
authors.forename: Masaki
authors.initials: M
authors.lastname: Takeda
authors.forename: Shigeru
authors.initials: S
authors.lastname: Oda
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Izumi
authors.forename: Ikuo
authors.initials: I
authors.lastname: Morita
mesh_terms: D017667:Adipocytes / Q000502:physiology; D000293:Adolescent; D000328:Adult; D000818:Animals; D000941:Antigens / Q000032:analysis; D051929:CD146 Antigen / Q000032:analysis; D002196:Capillaries / Q000166:cytology; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000502:physiology; D018920:Coculture Techniques; D042783:Endothelial Cells / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007150:Immunohistochemistry; D008297:Male; D010006:Osteoblasts / Q000502:physiology; D020286:Pericytes / Q000502:physiology*; D010513:Periodontal Ligament / Q000166:cytology*; D011509:Proteoglycans / Q000032:analysis; D051381:Rats; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000032:analysis; D013234:Stem Cells / Q000502:physiology*; D017154:Stromal Cells / Q000502:physiology; D014471:Umbilical Veins / Q000166:cytology; D055815:Young Adult; D000099216:Chondroitin Sulfate Proteoglycan 4
chemical_list: D000941:Antigens; D051929:CD146 Antigen; D011509:Proteoglycans; D020797:Receptor, Platelet-Derived Growth Factor beta; D000099216:Chondroitin Sulfate Proteoglycan 4; C497902:MCAM protein, human