title: Characterization of highly osteoblast/cementoblast cell clones from a CD105-enriched periodontal ligament progenitor cell population.
abstract: BACKGROUND
  It is known that periodontal ligament (PDL) harbors a heterogeneous progenitor cell population at different stages of lineage commitment. However, characterization of PDL stem cells committed to osteoblast/cementoblast (O/C) differentiation remains to be elucidated. The present study is carried out to isolate single cell-derived, cluster of differentiation (CD)105-positive PDL clones and to characterize the clones that present high potential to differentiate toward O/C phenotype in vitro.
  
  
  METHODS
  Isolation of single cell-derived colonies (clones) from a CD105-enriched PDL progenitor cell population was performed by the ring-cloning technique. Cell clones were evaluated for their O/C differentiation potential, metabolic activity, and expression of STRO-1 protein. Additionally, the clones that showed potential to O/C differentiation were characterized by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) for expression of runt-related transcriptor factor 2 (RUNX2), alkaline phosphatase, CD105, and CD166 during osteogenic induction.
  
  
  RESULTS
  Six PDL-CD105(+) clones were obtained, three being highly O/C clones (C-O) and three others that did not have the ability to produce mineralized matrix in vitro (C-F). The C-O group showed lower metabolic activity compared with the C-F group, and both cell groups were positively immunostained for STRO-1. qRT-PCR analysis demonstrated an increased expression of transcripts for RUNX2 and CD166 during the maturation of C-O cells toward O/C phenotype.
  
  
  CONCLUSIONS
  These results provide evidence that PDL-CD105(+) purified progenitor cells comprise a heterogeneous cell population that presents a cell subset with high O/C potential and, further, that surface antigen CD166 is modulated during the O/C maturation of this cell subset.
authors.affiliation: Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, University of Campinas, São Paulo, Brazil.
authors.forename: Miki T
authors.initials: MT
authors.lastname: Saito
authors.forename: Cristiane R
authors.initials: CR
authors.lastname: Salmon
authors.forename: Bruna R
authors.initials: BR
authors.lastname: Amorim
authors.forename: Gláucia M B
authors.initials: GM
authors.lastname: Ambrosano
authors.forename: Márcio Z
authors.initials: MZ
authors.lastname: Casati
authors.forename: Enilson A
authors.initials: EA
authors.lastname: Sallum
authors.forename: Francisco H
authors.initials: FH
authors.lastname: Nociti
authors.forename: Karina G
authors.initials: KG
authors.lastname: Silvério
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis; D015703:Antigens, CD / Q000032:analysis; D000954:Antigens, Surface / Q000032:analysis; D002448:Cell Adhesion / Q000502:physiology; D015816:Cell Adhesion Molecules, Neuronal / Q000032:analysis; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000502:physiology; D002469:Cell Separation; D002999:Clone Cells; D050659:Core Binding Factor Alpha 1 Subunit / Q000032:analysis; D003739:Dental Cementum / Q000166:cytology* / Q000378:metabolism; D000071063:Endoglin; D005326:Fetal Proteins / Q000032:analysis; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000502:physiology*; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D010012:Osteogenesis / Q000502:physiology; D010513:Periodontal Ligament / Q000166:cytology*; D010641:Phenotype; D011956:Receptors, Cell Surface / Q000032:analysis; D020410:Activated-Leukocyte Cell Adhesion Molecule
chemical_list: D000469:Alkaline Phosphatase; D015703:Antigens, CD; D000954:Antigens, Surface; D015816:Cell Adhesion Molecules, Neuronal; D050659:Core Binding Factor Alpha 1 Subunit; D000071063:Endoglin; D005326:Fetal Proteins; D011956:Receptors, Cell Surface; C105613:ALCAM protein, human; D020410:Activated-Leukocyte Cell Adhesion Molecule; C064206:ENG protein, human; C493709:RUNX2 protein, human; C525591:STRO-1 antigen, human
keywords: Cell biology; gene expression; molecular biology; osteoblasts; regeneration; tissue engineering