title: SSEA-1 isolates human endometrial basal glandular epithelial cells: phenotypic and functional characterization and implications in the pathogenesis of endometriosis.
abstract: OBJECTIVE
  Can the basal epithelial compartment of the human endometrium be defined by specific markers?
  
  
  CONCLUSIONS
  Human endometrial epithelial cells from the basalis express nuclear SOX9 and the cell-surface marker SSEA-1, with some cells expressing nuclear β-catenin. In vitro, primary endometrial epithelial cells enriched for SSEA-1+ show some features expected of the basalis epithelium.
  
  
  BACKGROUND
  The endometrial glands of the functionalis regenerate from the basalis gland stumps following menstruation. Endometriosis is thought to originate from abnormal dislocation of the basalis endometrium. In the highly regenerative intestinal epithelium, SOX9 and nuclear β-catenin are more highly expressed in the intestinal crypt, the stem/progenitor cell region.
  
  
  METHODS
  A large prospective observational study analysing full-thickness human endometrial hysterectomy samples from 115 premenopausal women, 15 post-menopausal women and ectopic endometriotic lesions from 20 women with endometriosis.
  
  
  METHODS
  Full-thickness endometrium from hysterectomy tissues was analysed by immunohistochemistry for SSEA-1, SOX9 and β-catenin. Primary human endometrial epithelial cells from short-term cultures were sorted into SSEA1+/- fractions with a cell sorter or magnetic beads and analysed for markers of differentiation and pluripotency and telomere lengths (TLs) using qPCR, telomerase activity [telomere repeat amplification protocol (TRAP)] and growth in 3D culture.
  
  
  RESULTS
  Similar to the intestinal crypt epithelium, human endometrial basal glandular epithelial cells expressed nuclear SOX9 and contained a rare subpopulation of cells with nuclear β-catenin suggestive of an activated Wnt pathway. The embryonic stem cell-surface marker, SSEA-1, also marked the human endometrial basal glandular epithelial cells, and isolated SSEA-1(+) epithelial cells grown in monolayer showed significantly higher expression of telomerase activity, longer mean TLs, lower expression of genes for steroid receptors and produced a significantly higher number of endometrial gland-like spheroids in 3D culture compared with SSEA-1(-) epithelial cells (P = 0.009). Cells in ectopic endometriosis lesions also expressed SSEA-1 and nuclear SOX9, suggesting that the basalis contributes to ectopic lesion formation in endometriosis following retrograde menstruation.
  
  
  CONCLUSIONS
  This is a descriptive study with only short-term culture of the primary human epithelial cells in vitro.
  
  
  CONCLUSIONS
  The surface marker SSEA1 enriches for an endometrial epithelial cell subpopulation from the basalis. Since the functional endometrium originates from these cells, it is now possible to study basalis epithelium for stem/progenitor cell activity to extend our current understanding of endometrial biology in health and diseases.
  
  
  BACKGROUND
  The work included in this manuscript was funded by Wellbeing of Women project grant RG1073 (D.K.H. and C.G.). We also acknowledge the support by National Health and Medical Research Council, RD Wright Career Development Award 465121 and Senior Research Fellowship 1042298, and the Victorian Government's Operation Infrastructure Support Program to C.G. and MRC G0601333 to T.V.Z. All authors have no conflict of interest to declare.
  
  
  BACKGROUND
  N/A.
authors.affiliation: Department of Women's and Children's Health, Institute of Translational Medicine, University of Liverpool, Liverpool Women's Hospital, Crown Street, Liverpool, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Valentijn
authors.forename: K
authors.initials: K
authors.lastname: Palial
authors.forename: H
authors.initials: H
authors.lastname: Al-Lamee
authors.forename: N
authors.initials: N
authors.lastname: Tempest
authors.forename: J
authors.initials: J
authors.lastname: Drury
authors.forename: T
authors.initials: T
authors.lastname: Von Zglinicki
authors.forename: G
authors.initials: G
authors.lastname: Saretzki
authors.forename: P
authors.initials: P
authors.lastname: Murray
authors.forename: C E
authors.initials: CE
authors.lastname: Gargett
authors.forename: D K
authors.initials: DK
authors.lastname: Hapangama
mesh_terms: D002454:Cell Differentiation; D002478:Cells, Cultured; D004715:Endometriosis / Q000378:metabolism / Q000473:pathology*; D004717:Endometrium / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D016256:Lewis X Antigen / Q000378:metabolism*; D008598:Menstruation / Q000378:metabolism; D008599:Menstruation Disturbances / Q000378:metabolism; D010641:Phenotype; D011446:Prospective Studies; D055758:SOX9 Transcription Factor / Q000378:metabolism; D019098:Telomerase / Q000378:metabolism; D059505:Telomere Homeostasis; D051176:beta Catenin / Q000378:metabolism
chemical_list: D016256:Lewis X Antigen; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; D051176:beta Catenin; D019098:Telomerase
keywords: 3D-culture; SOX9; SSEA-1; endometrium; β-catenin