title: Enrichment and identification of human 'fetal' epidermal stem cells.
abstract: BACKGROUND
  Human epidermis, a continuously renewing tissue, is maintained throughout life by stem cells that proliferate and replenish worn-out or damaged cells in the tissue. Cultured human epidermal stem cells have great potential in clinical application. However, isolating and culturing a pure population of epidermal stem cells has proven to be challenging.
  
  
  RESULTS
  We show that p63, a new marker for epidermal stem cells, is expressed in the basal layer of human fetal epidermis using immunohistochemistry, and that keratinocytes with the characteristics of stem cells can be isolated from the epidermis of aborted human fetuses aged >/=20 weeks based on high expression of beta(1) integrins by fluorescence-activated cell sorting. Furthermore, the enriched population showed the expression of molecular markers of putative human epidermal stem cells under a confocal microscope and a high colony formation efficiency when it was cultured at a clonal density. Under an electron microscope the sorted stem cells exhibited a high nuclear:cytoplasmic ratio and fewer organelles than the transit amplifying cells. The cultured epidermal stem cells can also be amplified and induced to terminal differentiation by suspension in vitro.
  
  
  CONCLUSIONS
  Human 'fetal' epidermal stem cells have been successfully isolated and cultured in vitro. The cultured human epidermal stem cells could be used as a tool for studying stem cell biology and testing stem cell therapy.
authors.affiliation: State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, 25 Beisihuanxilu, Beijing 100080, People's Republic of China.
authors.forename: Jia-xi
authors.initials: JX
authors.lastname: Zhou
authors.forename: Shu-yi
authors.initials: SY
authors.lastname: Chen
authors.forename: Wei-min
authors.initials: WM
authors.lastname: Liu
authors.forename: Yu-jing
authors.initials: YJ
authors.lastname: Cao
authors.forename: En-kui
authors.initials: EK
authors.lastname: Duan
mesh_terms: D015415:Biomarkers / Q000032:analysis; D002454:Cell Differentiation; D002455:Cell Division; D002469:Cell Separation; D002478:Cells, Cultured; D000078404:Epidermal Cells; D004817:Epidermis / Q000196:embryology*; D005333:Fetus / Q000166:cytology; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D019012:Integrin beta1 / Q000378:metabolism; D015603:Keratinocytes; D008565:Membrane Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D013234:Stem Cells / Q000166:cytology / Q000000981:diagnostic imaging / Q000378:metabolism; D014463:Ultrasonography
chemical_list: D015415:Biomarkers; C081876:CKAP4 protein, human; D019012:Integrin beta1; D008565:Membrane Proteins