Spatial-temporal regulation of the prostanoid receptor EP2 co-ordinates PGE2-mediated cAMP signaling in decidualizing human endometrium.

Decidualization denotes the differentiation of endometrial stromal cells into specialized decidual cells, essential for embryo implantation and pregnancy. The process requires coordination of progesterone and cAMP signaling, which converge on downstream transcription factors. PGE2 and relaxin, acting, respectively, through Gαs-coupled GPCRs EP2 and RXFP1, are putative candidates for generating cAMP in differentiating stromal cells.

The endoplasmic reticulum protein HSPA5/BiP is essential for decidual transformation of human endometrial stromal cells.

Decidualization denotes the process of inflammatory reprogramming of endometrial stromal cells (EnSC) into specialized decidual cells (DC). During this process, EnSC are subjected to endoplasmic reticulum (ER) stress as well as acute cellular senescence. Both processes contribute to the proinflammatory mid-luteal implantation window and their dysregulation has been implicated in reproductive failure.

Dynamic chromatin remodeling in cycling human endometrium at single-cell level.

Estrogen-dependent proliferation followed by progesterone-dependent differentiation of the endometrium culminates in a short implantation window. We performed single-cell assay for transposase-accessible chromatin with sequencing on endometrial samples obtained across the menstrual cycle to investigate the regulation of temporal gene networks that control embryo implantation. We identify uniquely accessible chromatin regions in all major cellular constituents of the endometrium, delineate temporal patterns of coordinated chromatin remodeling in epithelial and stromal cells, and gain mechanistic insights into the emergence of a receptive state through integrated analysis of enriched transcription factor (TF) binding sites in dynamic chromatin regions, chromatin immunoprecipitation sequencing analyses, and gene expression data.

Endometrial Assembloids to Model Human Embryo Implantation In Vitro.

Understanding the process of human embryo implantation is impeded by the inability to study this phenomenon in vivo, thus limiting opportunities to gain knowledge to in vitro modeling. Previous models have relied on monolayer co-cultures, which do not replicate the complexity of endometrial tissue. Here, we detail the establishment of three-dimensional endometrial assembloids, comprising gland-like epithelial organoids in a stromal matrix.

MicroRNAs emerging coordinate with placental mammals alter pathways in endometrial epithelia important for endometrial function.

We tested the hypothesis that conserved placental mammal-specific microRNAs and their targets facilitate endometrial receptivity to implantation. Expression of miR-340-5p, -542-3p, and -671-5p was regulated by exposure of endometrial epithelial cells to progesterone (10 μg/ml) for 24 h coordinate with 1,713 of their predicted targets. Proteomic analysis of cells transfected with miRNA mimic/inhibitor (48 h: n = 3) revealed 1,745 proteins altered by miR-340-5p (mimic; 1,369, inhibitor; 376) of which 171 were predicted targets and P4-regulated.

Miscarriage syndrome: Linking early pregnancy loss to obstetric and age-related disorders.

Upon embryo implantation, the uterine mucosa - the endometrium - transforms into a robust decidual matrix that accommodates the fetal placenta throughout pregnancy. This transition is driven by the differentiation of endometrial fibroblasts into specialised decidual cells. A synchronised influx of circulating natural killer (NK) cells and bone marrow-derived mesenchymal stem/progenitor cells (BM-MSC) is pivotal for decidual homeostasis and expansion in early pregnancy.

Organoids to model the endometrium: implantation and beyond.

Unlabelled: Despite advances in assisted reproductive techniques in the 4 decades since the first human birth after fertilisation, 1-2% of couples experience recurrent implantation failure, and some will never achieve a successful pregnancy even in the absence of a confirmed dysfunction. Furthermore, 1-2% of couples who do conceive, either naturally or with assistance, will experience recurrent early loss of karyotypically normal pregnancies. In both cases, embryo-endometrial interaction is a clear candidate for exploration.

Maternal selection of human embryos in early gestation: Insights from recurrent miscarriage.

Compared to most mammals, human pregnancy is unusual in that it involves chromosomally diverse embryos, cyclical breakdown and regeneration of the uterine mucosa, and intimate integration of fetal and maternal cells at the uteroplacental interface. Not surprisingly, pregnancy often falters in early gestation. Whether these losses result in clinical miscarriages depends on the origins and impacts of chromosomal errors on fetal development and the ability of the decidualizing endometrium to engage in embryo biosensing and selection.

EndoTime: non-categorical timing estimates for luteal endometrium.

Study Question: Can the accuracy of timing of luteal phase endometrial biopsies based on urinary ovulation testing be improved by measuring the expression of a small number of genes and a continuous, non-categorical modelling approach?

Summary Answer: Measuring the expression levels of six genes (IL2RB, IGFBP1, CXCL14, DPP4, GPX3 and SLC15A2) is sufficient to obtain substantially more accurate timing estimates and to assess the reliability of timing estimates for each sample.

What Is Known Already: Commercially available endometrial timing approaches based on gene expression require large gene sets and use a categorical approach that classifies samples as pre-receptive, receptive or post-receptive.

Study Design, Size, Duration: Gene expression was measured by RTq-PCR in different sample sets, comprising a total of 664 endometrial biopsies obtained 4-12 days after a self-reported positive home ovulation test.

Modelling the impact of decidual senescence on embryo implantation in human endometrial assembloids.

Decidual remodelling of midluteal endometrium leads to a short implantation window after which the uterine mucosa either breaks down or is transformed into a robust matrix that accommodates the placenta throughout pregnancy. To gain insights into the underlying mechanisms, we established and characterized endometrial assembloids, consisting of gland-like organoids and primary stromal cells. Single-cell transcriptomics revealed that decidualized assembloids closely resemble midluteal endometrium, harbouring differentiated and senescent subpopulations in both glands and stroma.

Characterization of highly proliferative decidual precursor cells during the window of implantation in human endometrium.

Pregnancy depends on the wholesale transformation of the endometrium, a process driven by differentiation of endometrial stromal cells (EnSC) into specialist decidual cells. Upon embryo implantation, decidual cells impart the tissue plasticity needed to accommodate a rapidly growing conceptus and invading placenta, although the underlying mechanisms are unclear. Here we characterize a discrete population of highly proliferative mesenchymal cells (hPMC) in midluteal human endometrium, coinciding with the window of embryo implantation.

Embryo biosensing by uterine natural killer cells determines endometrial fate decisions at implantation.

Decidualizing endometrial stromal cells (EnSC) critically determine the maternal response to an implanting conceptus, triggering either menstruation-like disposal of low-fitness embryos or creating an environment that promotes further development. However, the mechanism that couples maternal recognition of low-quality embryos to tissue breakdown remains poorly understood. Recently, we demonstrated that successful transition of the cycling endometrium to a pregnancy state requires selective elimination of pro-inflammatory senescent decidual cells by activated uterine natural killer (uNK) cells.

Exometabolomic Analysis of Decidualizing Human Endometrial Stromal and Perivascular Cells.

Differentiation of endometrial fibroblasts into specialized decidual cells controls embryo implantation and transforms the cycling endometrium into a semi-permanent, immune-protective matrix that accommodates the placenta throughout pregnancy. This process starts during the midluteal phase of the menstrual cycle with decidual transformation of perivascular cells (PVC) surrounding the terminal spiral arterioles and endometrial stromal cells (EnSC) underlying the luminal epithelium. Decidualization involves extensive cellular reprogramming and acquisition of a secretory phenotype, essential for coordinated placental trophoblast invasion.

Vascular Adhesion Protein-1 Determines the Cellular Properties of Endometrial Pericytes.

Vascular adhesion protein-1 (VAP-1) is an inflammation-inducible adhesion molecule and a primary amine oxidase involved in immune cell trafficking. Leukocyte extravasation into tissues is mediated by adhesion molecules expressed on endothelial cells and pericytes. Pericytes play a major role in the angiogenesis and vascularization of cycling endometrium.

Periconception maternal low-protein diet adversely affects male mouse fetal bone growth and mineral density quality in late gestation.

Adverse programming of adult non-communicable disease can be induced by poor maternal nutrition during pregnancy and the periconception period has been identified as a vulnerable period. In the current study, we used a mouse maternal low-protein diet fed either for the duration of pregnancy (LPD) or exclusively during the preimplantation period (Emb-LPD) with control nutrition provided thereafter and postnatally to investigate effects on fetal bone development and quality. This model has been shown previously to induce cardiometabolic and neurological disease phenotypes in offspring.

Recurrent pregnancy loss is associated with a pro-senescent decidual response during the peri-implantation window.

During the implantation window, the endometrium becomes poised to transition to a pregnant state, a process driven by differentiation of stromal cells into decidual cells (DC). Perturbations in this process, termed decidualization, leads to breakdown of the feto-maternal interface and miscarriage, but the underlying mechanisms are poorly understood. Here, we reconstructed the decidual pathway at single-cell level in vitro and demonstrate that stromal cells first mount an acute stress response before emerging as DC or senescent DC (snDC).

Impact of sitagliptin on endometrial mesenchymal stem-like progenitor cells: A randomised, double-blind placebo-controlled feasibility trial.

Background: Recurrent pregnancy loss (RPL) is associated with the loss of endometrial mesenchymal stem-like progenitor cells (eMSC). DPP4 inhibitors may increase homing and engraftment of bone marrow-derived cells to sites of tissue injury. Here, we evaluated the effect of the DPP4 inhibitor sitagliptin on eMSC in women with RPL, determined the impact on endometrial decidualization, and assessed the feasibility of a full-scale clinical trial.

Single-Cell Transcriptomics: A High-Resolution Avenue for Plant Functional Genomics.

Plant function is the result of the concerted action of single cells in different tissues. Advances in RNA-seq technologies and tissue processing allow us now to capture transcriptional changes at single-cell resolution. The incredible potential of single-cell RNA-seq lies in the novel ability to study and exploit regulatory processes in complex tissues based on the behaviour of single cells.

Analysis of chromatin accessibility in decidualizing human endometrial stromal cells.

Spontaneous decidualization of the endometrium in response to progesterone signaling is confined to menstruating species, including humans and other higher primates. During this process, endometrial stromal cells (EnSCs) differentiate into specialized decidual cells that control embryo implantation. We subjected undifferentiated and decidualizing human EnSCs to an assay for transposase accessible chromatin with sequencing (ATAC-seq) to map the underlying chromatin changes.

Clearance of senescent decidual cells by uterine natural killer cells in cycling human endometrium.

In cycling human endometrium, menstruation is followed by rapid estrogen-dependent growth. Upon ovulation, progesterone and rising cellular cAMP levels activate the transcription factor Forkhead box O1 (FOXO1) in endometrial stromal cells (EnSCs), leading to cell cycle exit and differentiation into decidual cells that control embryo implantation. Here we show that FOXO1 also causes acute senescence of a subpopulation of decidualizing EnSCs in an IL-8 dependent manner.

The Long-Term Effects of the Periconceptional Period on Embryo Epigenetic Profile and Phenotype; The Paternal Role and His Contribution, and How Males Can Affect Offspring's Phenotype/Epigenetic Profile.

The number of adults afflicted with heart disease, obesity and diabetes, central components of metabolic disorder, has grown rapidly in recent decades, affecting up to one quarter of the world's population. Typically, these diseases are attributed to lifestyle factors such as poor diet, lack of exercise and smoking. However, studies have now identified strong associations between patterns of growth during foetal and neonatal life and an increase predisposition towards developing heart disease, obesity and diabetes in adult life.

Deregulation of the endometrial stromal cell secretome precedes embryo implantation failure.

Study Question: Is implantation failure following ART associated with a perturbed decidual response in endometrial stromal cells (EnSCs)?

Summary Answer: Dynamic changes in the secretome of decidualizing EnSCs underpin the transition of a hostile to a supportive endometrial microenvironment for embryo implantation; perturbation in this transitional pathway prior to ART is associated with implantation failure.

What Is Known Already: Implantation is the rate-limiting step in ART, although the contribution of an aberrant endometrial microenvironment in IVF failure remains ill defined.

Study Design, Size, Duration: In vitro characterization of the temporal changes in the decidual response of primary EnSCs isolated prior to a successful or failed ART cycle.

Success after failure: the role of endometrial stem cells in recurrent miscarriage.

Endometrial stem-like cells, including mesenchymal stem cells (MSCs) and epithelial progenitor cells, are essential for cyclic regeneration of the endometrium following menstrual shedding. Emerging evidence indicates that endometrial MSCs (eMSCs) constitute a dynamic population of cells that enables the endometrium to adapt in response to a failed pregnancy. Recurrent miscarriage is associated with relative depletion of endometrial eMSCs, which not only curtails the intrinsic ability of the endometrium to adapt to reproductive failure but also compromises endometrial decidualization, an obligatory transformation process for embryo implantation.