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ObjectiveTo investigate the impact of the androgen precursor dehydroepiandrosterone (DHEA) on the decidualization of human endometrial stromal cells isolated from women of advanced reproductive age.DesignIn vitro study.SettingUniversity research institute.Patient(s)Proliferative phase primary human endometrial stromal fibroblasts (hESFs) were isolated from women of advanced reproductive age (n = 16; mean age, 44.7 ± 2.3). None of the women were receiving hormone therapy or had endometriosis.Intervention(s)Isolated hESFs were decidualized in vitro by incubation with P (1 μM) and cAMP (0.1 mg/mL) in the presence, or absence, of DHEA (10 nM, 100 nM).Main Outcome Measure(s)Secretion of androgens was assessed by ELISA. Expression of decidualization markers and endometrial receptivity markers was assessed by quantitative polymerase chain reaction and ELISA.Result(s)Decidualization responses were retained in hESF isolated from women of advanced reproductive age. Supplementation with DHEA increased androgen biosynthesis and concentrations of T and dihydrotestosterone were ∼3× greater after coincubation with DHEA compared with hESF stimulated with decidualization alone. Addition of DHEA to decidualized hESF increased expression of the decidualization markers IGFBP1 and PRL and the endometrial receptivity marker SPP1. DHEA enhanced secretion of IGFBP1, PRL, and SPP1 proteins maximally by day 8 of the decidualization time course concomitant with peak androgen concentrations.Conclusion(s)These novel results demonstrate DHEA can enhance in vitro decidualization responses of hESF from women of advanced reproductive age. Supplementation with DHEA during the receptive phase may augment endometrial function and improve pregnancy rates in natural or assisted reproductive cycles.

The human endometrium experiences repetitive cycles of tissue wounding characterised by piecemeal shedding of the surface epithelium and rapid restoration of tissue homeostasis. In this study we used a mouse model of endometrial repair and three transgenic lines of mice to investigate whether epithelial cells that become incorporated into the newly formed luminal epithelium have their origins in one or more of the mesenchymal cell types present in the stromal compartment of the endometrium. Using scRNAseq we identified a novel population of PDGFRb+ mesenchymal stromal cells that developed a unique transcriptomic signature in response to endometrial breakdown/repair. These cells expressed genes usually considered specific to epithelial cells and in silico trajectory analysis suggested they were stromal fibroblasts in transition to becoming epithelial cells. To confirm our hypothesis we used a lineage tracing strategy to compare the fate of stromal fibroblasts (PDGFRa+) and stromal perivascular cells (NG2/CSPG4+). We demonstrated that stromal fibroblasts can undergo a mesenchyme to epithelial transformation and become incorporated into the re-epithelialised luminal surface of the repaired tissue. This study is the first to discover a novel population of wound-responsive, plastic endometrial stromal fibroblasts that contribute to the rapid restoration of an intact luminal epithelium during endometrial repair. These findings form a platform for comparisons both to endometrial pathologies which involve a fibrotic response (Asherman’s syndrome, endometriosis) as well as other mucosal tissues which have a variable response to wounding.