Endocrine Abstracts

JOINT1677

Objective: Women with polycystic ovary syndrome (PCOS) experience reduced fertility associated with implantation failure, miscarriage and endometrial cancer, all linked to endometrial dysfunction¹. Recently, we have created a single-nuclei transcriptomic atlas of the endometrium of women with PCOS². Creating in vitro endometrial models is essential for studying PCOS-related dysfunction and treatments. This study develops three-dimensional (3D) endometrial epithelial organoids (EEOs) and single-layer stromal cells from endometrial biopsies of PCOS patients and controls to assess phenotype retention. Transcriptome profiling of EEOs and decidualized stromal cells is also included.

Methods: The 3D EEOs and the single-layer endometrial stromal cells are established from fresh endometrial biopsies of women with and without PCOS. Immunofluorescence staining showed that the EEOs consist of an intact proliferative basolateral epithelial membrane integrity. EEOs (n = 4 PCOS, n = 4 control) were subjected to hormone treatment (estrogen, progesterone and cyclic adenosine monophosphate, cAMP) over six days, with bulk RNA sequencing performed at day 0, day 2 and day 6. Similarly, single-layer endometrial stromal cells (n = 3 PCOS, n = 3 control) were treated with estrogen, progesterone and cAMP for 14 days and analysed for transcriptomic changes and cellular respiration using Seahorse XFe.

Results: EEOs displayed proliferative basolateral integrity and hormone responsiveness but lacked a strong PCOS signature in a static hormonal environment. To better mimic physiological conditions, a microfluidic system is being developed to simulate normal and anovulatory PCOS cycles. In contrast, stromal cells retained more PCOS-specific traits, exhibiting altered decidualization responses and differences in progesterone receptor expression. Metabolic assays showed lower maximum respiration rates in PCOS stromal cells, and transcriptomic analysis revealed disruptions in progesterone signaling, mitochondrial function, and inflammation—potential contributors to implantation failure and adverse pregnancy outcomes.

Conclusion: These preliminary findings indicate that under a static hormonal environment in vitro, EEOs lose their PCOS phenotype, whereas stromal cells retain more PCOS-specific characteristics. This suggests that the in vitro conditions do not fully replicate the dynamic hormonal environment of the menstrual cycle. Integrating insights from the altered decidualization response in PCOS will further refine in vitro modeling, helping to elucidate the mechanistic underpinnings of endometrial dysfunction in PCOS and identify potential therapeutic targets.

References: 1. Stener-Victorin, E., et al. (2024). Polycystic ovary syndrome. Nat Rev Dis Primers 10, 27. 10.1038/s41572-024-00511-3.

2. Eriksson, G., et al. (2025). Single-Cell Profiling of the Human Endometrium in Polycystic Ovary Syndrome: Uncovering Disease Signatures and Treatment Responses. Accepted for publication, January 21, Nature Medicine.