Lightning Talk + Poster ESA-SRB-ANZOS 2025 in conjunction with ENSA

Unravelling the molecular signature of human endometrial stem/progenitor cells to understand endometrial regeneration and differentiation (128735)

Harriet Fitzgerald 1 2 , Sally Mortlock 3 , Fiona Cousins 1 2 , Elizabeth Marquez-Garcia 2 , Brett McKinnon 3 , Luk Rombauts 1 4 , Jim Tsaltas 1 4 , Grant Montgomery 3 , Caroline Gargett 1 2
  1. Department of Obstetrics and Gynaecology, Monash University, Clayton, VIC, Australia
  2. The Ritchie Centre, Hudson Institute of Medical Research, Clayton, VIC, Australia
  3. Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
  4. Gynaecological Endoscopy and Endometriosis Surgery Unit, Monash Health, Clayton

The human endometrium is a highly regenerative tissue undergoing >400 cycles of shedding, regeneration, proliferation and differentiation during a woman’s reproductive life. The endometrium has two layers, an upper functionalis (shed during menstruation) and a basalis layer that is retained and is from which the new functionalis forms. Adult stem cells reside in the basalis human endometrium including N-cadherin+ (CDH2) epithelial progenitors and mesenchymal stem cells. Perturbations in these stem/progenitor cells likely leads to endometrial dysfunction, gynaecological disease and infertility. Our aim was to define the molecular signature of human endometrial stem/progenitor cells to better understand their role in endometrial regeneration, differentiation and disease.

Human hysterectomy endometrium (n=5) was digested to single cells for 6-way FACSorting to enrich for stem/progenitor cell subpopulations. The six cell fractions were combined and analysed by single cell RNA sequencing (scRNAseq). Immunofluorescence examined the endometrial localisation of thyrotropin releasing hormone (TRH) and Indian Hedgehog (IHH) co-localisation of SSEA-1, CDH2 and IHH, and BOC and SSEA-1.

scRNAseq identified four populations of endometrial stem/progenitor populations of epithelial and mesenchymal origin from a total of 16 cell populations. Epithelial progenitors transitioned into mature cell states including a novel population in the junctional zone between the glands and luminal epithelium. Epithelial progenitors had high expression of TRH and IHH. Thyroid signalling pathway featured prominently in epithelial progenitors. TRH and IHH localised to the basalis endometrial glandular epithelia. CDH2, SSEA-1 and IHH co-localised in the basalis endometrial glands. Key interactions were identified between IHH in epithelial progenitors and its co-receptors BOC and CDON in the stroma. BOC and SSEA-1 co-localised in the glandular and luminal epithelia.

Determining novel roles for IHH and TRH signalling in endometrial epithelial progenitors provides fundamental understanding of the regenerating endometrium and the potential pathogenesis of endometrial proliferative disorders such as endometriosis, adenomyosis, and infertility.