Page 24 - HKSEMR2020 Programme book

Poster Presentation (Basic Science) Abstracts

The WNT receptor FZD5 is required for the maintenance of

endometrial mesenchymal stem-like cells

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Tianqi Li , RWS Chan , RHW Li , PCN Chiu , EHY Ng , WSB Yeung 2
1.Department of Obstetrics and Gynecology, University of Hong Kong, Hong Kong, SAR, China.; 2. Shenzhen Key
Laboratory of Fertility Regulation, The University of Hong Kong Shenzhen Hospital, Shenzhen, China.
Introduction / Background / Objectives: by counting the colonies formed and phenotypic expression of
the eMSC markers (CD140b+CD146+ cells) was analyzed by
Human endometrium is a dynamic tissue that undergoes cyclical
regeneration under the regulation of sex steroids. The existence flow cytometry. Gene and protein expression of WNT receptors
of endometrial mesenchymal stem-like cells (eMSCs) can were assessed by quantitative PCR and immunofluorescence,
contribute to this remarkable regenerative capacity. Previously, respectively.
we demonstrated that myometrial cells can activate WNT/
β-catenin signaling via WNT5A to maintain the self-renewal Results / Outcomes:
capacity of eMSCs. However, there is limited knowledge on the
WNT5A-responsive stem cells in the niche. WNT ligands bind to Assessment of stromal subpopulations revealed a significantly
products of the frizzled (FZD) family and co-receptor low density higher level of FZD5 gene expression in eMSCs compared to
lipoprotein receptor-related protein 5 (LRP5) to activate the WNT unfractionated stromal and progenitor cells (n = 12, P < 0.05).
signaling pathway. In this study, we examined the protein and gene EMSCs abundantly express FZD5 protein (97.6 ± 1.24%, n =
expression of frizzled receptors that have been reported to interact 5). FZD5 is a classic receptor of WNT5A and has been reported
with WNT5A in three subpopulations of endometrial stromal cells: to activate both WNT/β-catenin dependent (canonical) and
unfractionated stromal cells, progenitor cells (CD140b+CD146- independent (non-canonical) signaling. Addition of neutralizing
cells) and eMSCs (CD140b+CD146+ cells). We further evaluated anti-FZD5 antibody reduced the stimulatory effect of co-cultured
the importance of the WNT-FZD interaction in eMSCs proliferation myometrial cells or WNT5A CM on clonogenicity (n = 5, P < 0.05)
and self-renewal. and expression of active β-catenin (ABC) in eMSCs (n = 5, P < 0.01).
Moreover, knockdown of FZD5 protein using FZD5-siRNA reduced
the induction effect of myometrial cells or WNT5A CM induction
Methods: effect when we measured the TCF/LEF luciferase activity (n = 6,
P < 0.05) and ABC expression in eMSCs (n = 5, P < 0.05) when
Endometrial tissues were obtained from women undergoing
hysterectomy. Single cell suspension was obtained by enzymatic compared to control siRNA.
digestion, and red blood cells and leukocytes were removed by
ficoll-paque and CD45 dynabeads, respectively. EMSCs were Conclusion:
isolated by sequential beading with magnetic beads coated with
anti-CD140b and anti-CD146 antibodies. EMSCs were co-cultured In conclusion, our findings suggest that myometrial-secreted
with myometrial cells at a ratio of 1:90 or with WNT5A conditioned WNT5A interact with FZD5 to modulate the self-renewal of eMSCs
medium (CM) for 15 days. The clonogenicity was determined by the activation of WNT/β-catenin pathway.

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