Epithelial progenitor cells have been identified in human endometrium and may mediate endometrial regeneration. The canonical Wnt pathway is important in adult stem cell self-renewal and in estrogen-induced endometrial regeneration. A recent gene profiling study showed differential expression of 22 Wnt-associated genes between purified pre- and post-menopausal endometrial epithelial cells¹. Further analysis identified an adhesion molecule as a candidate marker for human endometrial epithelial progenitor cells. The aim of this study was to examine the expression of 12 Wnt associated genes in human endometrial epithelial cells enriched and depleted for the candidate marker.

Endometrial epithelial cells were obtained from 11 hysterectomy samples from reproductive aged women not taking hormones. Tissue was dissociated to single cells and sorted into enriched and depleted fractions using antibody-coated magnetic beads to the candidate marker. RNA was extracted and qPCR undertaken for the 12 Wnt-related genes using published primers.¹  Immunofluorescence was performed on frozen sections of full thickness endometrium.

We found differential expression of 8 of the 12 genes between proliferative (n=5) and secretory stage (n=6) samples. No difference for any of the 12 genes between enriched and depleted epithelial progenitor cell populations was observed in the proliferative stage. Surprisingly, we found significantly higher expression (P<0.05)  of WNT10A ligand, FZD9 receptor, GSK3B kinase, SOX9 transcription factor, and Wnt targets TLE1, SMO, MMP7 and VANGL2 in the marker depleted differentiated cells compared to the putative marker enriched progenitor cells. Regulators of Wnt signalling, AXIN2 and β-catenin localised to both marker enriched and depleted populations in pre and post-menopausal endometrium. Unexpectedly we found SOX9 specifically co-localised with β-tubulin immunostained cilia of the marker negative epithelial cells.

Our data suggest that Wnt-related genes are more highly expressed in differentiated endometrial epithelial cells rather than putative epithelial progenitor cells, indicating their possible role in the differentiation into secretory glands.