title: Isolation and characterization of multipotent human periodontal ligament stem cells.
abstract: BACKGROUND
  Periodontal ligament (PDL) repair is thought to involve mesenchymal progenitor cells capable of forming fibroblasts, osteoblasts and cementoblasts. However, full characterization of PDL stem cell (SC) populations has not been achieved.
  
  
  OBJECTIVE
  To isolate and characterize PDLSC and assess their capability to differentiate into bone, cartilage and adipose tissue.
  
  
  METHODS
  Human PDL cells were stained for STRO-1, FACS sorted and expanded in culture. Human bone marrow SC (BMSC) served as a positive control. PDLSC and BMSC were cultured using standard conditions conducive for osteogenic, chondrogenic and adipogenic differentiation. Osteogenic induction was assayed using alizarine red S staining and expression of alkaline phosphatase (ALP) and bone sialoprotein (BSP). Adipogenic induction was assayed using Oil Red O staining and the expression of PPAR gamma 2 (early) and LPL (late) adipogenic markers. Chondrogenic induction was assayed by collagen type II expression and toluidine blue staining.
  
  
  RESULTS
  Human PDL tissue contains about 27% STRO-1 positive cells with 3% strongly positive. In osteogenic cultures ALP was observed by day-7 in BMSC and day-14 in PDLSC. BSP expression was detectable by day-7; with more intense staining in PDLSC cultures. In adipogenic cultures both cell populations showed positive Oil Red O staining by day-25 with PPAR gamma 2 and LPL expression. By day-21, both BMSC and PDLSC chondrogenic induced cultures expressed collagen type II and glycosaminoglycans.
  
  
  CONCLUSIONS
  The PDL contains SC that have the potential to differentiate into osteoblasts, chondrocytes and adipocytes, comparable with previously characterized BMSC. This adult PDLSC population can be utilized for potential therapeutic procedures related to PDL regeneration.
authors.affiliation: Institute of Oral Health Research, School of Dentistry, University of Alabama at Birmingham, Birmingham, AL 35294-0007, USA.
authors.forename: I C
authors.initials: IC
authors.lastname: Gay
authors.forename: S
authors.initials: S
authors.lastname: Chen
authors.forename: M
authors.initials: M
authors.lastname: MacDougall
mesh_terms: D050156:Adipogenesis / Q000502:physiology; D000273:Adipose Tissue / Q000166:cytology; D053687:Adult Stem Cells / Q000166:cytology*; D000469:Alkaline Phosphatase / Q000032:analysis; D000880:Anthraquinones; D001391:Azo Compounds; D001842:Bone and Bones / Q000166:cytology; D002356:Cartilage / Q000166:cytology; D002454:Cell Differentiation; D002469:Cell Separation; D020219:Chondrogenesis / Q000502:physiology; D024043:Collagen Type II / Q000032:analysis; D004396:Coloring Agents; D005434:Flow Cytometry; D006025:Glycosaminoglycans / Q000032:analysis; D006412:Hematopoietic Stem Cells / Q000166:cytology; D006801:Humans; D058574:Integrin-Binding Sialoprotein; D008071:Lipoprotein Lipase / Q000032:analysis; D039902:Multipotent Stem Cells / Q000166:cytology*; D009687:Nuclear Proteins / Q000032:analysis; D010012:Osteogenesis / Q000502:physiology; D047495:PPAR gamma / Q000032:analysis; D010513:Periodontal Ligament / Q000166:cytology*; D012795:Sialoglycoproteins / Q000032:analysis
chemical_list: D000880:Anthraquinones; D001391:Azo Compounds; D024043:Collagen Type II; D004396:Coloring Agents; D006025:Glycosaminoglycans; C546871:IBSP protein, human; D058574:Integrin-Binding Sialoprotein; D009687:Nuclear Proteins; D047495:PPAR gamma; C108522:STAG1 protein, human; D012795:Sialoglycoproteins; C004468:Alizarin Red S; D008071:Lipoprotein Lipase; D000469:Alkaline Phosphatase; C011049:oil red O