title: Hypoxia-amplified proliferation of human dental pulp cells.
abstract: BACKGROUND
  Postnatal human dental pulp is a potentially promising source of progenitor cells. Sustaining and amplifying progenitor cell populations would be beneficial for basic science research with application in pulpal regeneration. Hypoxia has been observed to promote the undifferentiated cell state in various stem cell populations. The purpose of this study was to examine human dental pulp cells (DPCs) proliferation in normoxia and hypoxia.
  
  
  METHODS
  Dental pulp cells were obtained from third molars of adult patients and cultured in alpha modification of Eagle's medium culture medium with 10% fetal bovine serum. For cell proliferation, DPCs were divided into two groups: (1) DPCs incubated in normoxic conditions (20% oxygen tension) and (2) DPC incubated in hypoxic conditions (3% oxygen tension). Cell proliferation assays were performed every 2 to 3 days from day 3 to day 14 by trypsinization and quantification of cells with a hemacytometer. Fluorescence-activated cell sorting analysis was completed to investigate stem cell markers, CD133, and STRO-1.
  
  
  RESULTS
  DPCs proliferated significantly more in hypoxia than in normoxia (ie, two-fold throughout the experiment, p < 0.0001). The primitive stem cell marker, CD133, decreased in hypoxia, whereas the osteoprogenitor marker, STRO-1, increased by 8.5-fold.
  
  
  CONCLUSIONS
  This study suggested that hypoxia is an effective treatment to amplify numbers of progenitor cells from human dental pulp.
authors.affiliation: Department of Restorative Dentistry, Harvard School of Medicine, Boston, MA 02115, USA. bjsakdee@post.harvard.edu
authors.forename: Jaruma Beau
authors.initials: JB
authors.lastname: Sakdee
authors.forename: Robert R
authors.initials: RR
authors.lastname: White
authors.forename: Tom C
authors.initials: TC
authors.lastname: Pagonis
authors.forename: Peter V
authors.initials: PV
authors.lastname: Hauschka
mesh_terms: D000071916:AC133 Antigen; D000328:Adult; D015703:Antigens, CD / Q000032:analysis; D000954:Antigens, Surface / Q000032:analysis; D002452:Cell Count; D015687:Cell Hypoxia / Q000502:physiology*; D049109:Cell Proliferation; D002469:Cell Separation; D002478:Cells, Cultured; D003782:Dental Pulp / Q000166:cytology*; D005434:Flow Cytometry; D006023:Glycoproteins / Q000032:analysis; D006801:Humans; D010455:Peptides / Q000032:analysis; D013234:Stem Cells / Q000166:cytology*
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D000954:Antigens, Surface; D006023:Glycoproteins; C000606023:PROM1 protein, human; D010455:Peptides; C525591:STRO-1 antigen, human