What exactly is endometrial receptivity?

hsa_circ_001946 elevates HOXA10 expression and promotes the development of endometrial receptivity via sponging miR-135b

Background

Impaired endometrial receptivity is a major reason for embryo implantation failure. There’s a paucity of information regarding the role of circRNAs on endometrial receptivity. Here, we investigated the function of hsa_circ_001946 on endometrial receptivity and its mechanisms.

Methods

A total of 50 women composing 25 with recurrent implantation failure and 25 who conceived after their implantation were recruited in this study. Expression of hsa_circ_001946, miR-135b, and HOXA10 was evaluated by quantitative RT-PCR (qRT-PCR) in biopsied endometrial tissue samples. The levels of HOXA10, and cell cycle markers (CCNB1, CDK1, and CCND1) were determined by IHC and western blotting assays. Binding relationship among miR-135b, hsa_circ_001946 and HOXA10 were confirmed by dual luciferase reporter assays and western blotting. MTT assays and cell cycle assays by FACS were employed to evaluate the proliferation and cell cycle of cells. T-HESCs were cultured with 1 µM medroxyprogesterone acetate (MPA) and 0.5 mM 8-bromoadenosine 3’:5’-cyclic monophosphate (8-Br-cAMP) to induce decidualization. The mechanisms and functions of hsa_circ_001946 on decidualization were further assessed by qRT-PCR evaluating the expression of hsa_circ_001946, miR-135b, HOXA10 and decidual markers (PRL and IGFBP1) in T-HESCs.

Results

Endometrial tissues from patients with recurrent implantation failure had lower hsa_circ_001946 expression, higher miR-135b expression, and lower HOXA10 expression. Hsa_circ_001946 promoted HOXA10 expression by sponging miR-135b in T-HESCs. Overexpression of hsa_circ_001946 restored cell proliferation and cell cycle that were disrupted by miR-135b overexpression in T-HESCs. Decidualized T-HESCs had higher hsa_circ_001946 expression, lower miR-135b expression, and higher HOXA10 expression. Overexpression of hsa_circ_001946 reversed the expression of decidual markers (PRL and IGFBP1) that were suppressed by miR-135b overexpression in T-HESCs.

Conclusions

In conclusion, our findings suggest that hsa_circ_001946 promotes cell proliferation and cell cycle process and increases expression of decidualization markers to enhance endometrial receptivity progression via sponging miR-135b and elevating HOXA10.

The Efficacy of Complementary and Alternative Medicine in the Treatment of Female Infertility

Female infertility is a state of fertility disorder caused by multiple reasons. The incidence of infertility for females has significantly increased due to various factors such as social pressure, late marriage, and late childbirth, and its harm includes heavy economic burden, psychological shadow, and even marriage failure. Conventional solutions, such as hormone therapy, in vitro fertilization (IVF), and embryo transfer, have the limitations of unsatisfied obstetric outcomes and serious adverse events. Currently, complementary and alternative medicine (CAM), as a new treatment for infertility, is gradually challenging the dominant position of traditional therapies in the treatment of infertility. CAM claims that it can adjust and harmonize the state of the female body from a holistic approach to achieve a better therapeutic effect and has been increasingly used by infertile women. Meanwhile, some controversial issues also appeared; that is, some randomized controlled trials (RCTs) confirmed that CAM had no obvious effect on infertility, and the mechanism of its effect could not reach a consensus. To clarify CAM effectiveness, safety, and mechanism, this paper systematically reviewed the literature about its treatment of female infertility collected from PubMed and CNKI databases and mainly introduced acupuncture, moxibustion, and oral Chinese herbal medicine. In addition, we also briefly summarized psychological intervention, biosimilar electrical stimulation, homeopathy, hyperbaric oxygen therapy, etc.

MicroRNA: Could It Play a Role in Bovine Endometritis?

Endometritis in dairy cows is a major economic problem worldwide; without advances in lifestyle management and drug treatment, it causes high morbidity and death. Micro ribonucleic acid (miRNAs) these days is seen as an important part of gene control networks. It is a class of small nucleotides 20-25, single-stranded RNA molecules. In endometritis, the inflammatory response caused by the gram-negative bacteria Escherichia coli (E. coli) alters the expression of miRNA which can regulate the innate immune system. This manuscript reviews (1) the interaction of miRNAs with the signaling of NF-κB and dysregulation of miRNAs and NF-κB activity in endometritis and (2) the activity of miR-let-7c, miR-148a, and miR-488 in NF-κB activation and their effect on endometritis. Cows with reduced immunity are more vulnerable to transition diseases, such as endometritis. During post-partum, cows undergo stress, metabolic disorders, hormonal imbalance, negative energy balance, and changes in diet. One of the many categories of regulatory molecules, which explain its natural function and pathological impact on NF-κB dysregulation, is important to inform the complexity of the immune system and to develop treatments for endometritis. It shows that miRNAs could have multiple applications in veterinary medicine. Nevertheless, a comprehensive study of is essential which should be aimed at exploring the role of microRNA at physiological level and its effect due to dysfunction and dysregulation.

Electroacupuncture Improves Pregnancy Outcomes in Rats with Thin Endometrium by Promoting the Expression of Pinopode-Related Molecules

A thin endometrium affects the success of assisted reproduction due to low endometrial receptivity. Acupuncture improves endometrial receptivity and promotes the formation of pinopodes, the ultrastructure marker implantation window. However, the specific underlying mechanisms remain unclear. In this study, the efficacy of acupuncture treatment and its underlying mechanism were investigated by analyzing pregnancy rate, pinopode formation, and related molecular markers in thin endometrium model rats. Absolute ethanol (95%) was injected into the uteruses of female Sprague-Dawley rats to construct a thin endometrium model. In this model, acupuncture stimulation at EX-CA1, SP6, and CV4 ameliorated the pregnancy rate. Significantly increased embryo implantation, endometrial thickness, numbers of glands, and blood vessels were observed in the electroacupuncture (EA) group compared to the model group. The number of pinopodes in the EA group was abundant, with a shape similar to that of the control group. Additionally, significantly higher expression levels of pinopode-related markers, including integrin αvβ3, homeobox A10 (HOXA10), heparin-binding EGF-like growth factor (HBEGF), estrogen receptor alpha (ERα), and progesterone receptor (PR), were observed in the EA group than those in the model group. In conclusion, EA had a positive effect on the endometrial receptivity of thin endometrium model rats by improving pinopode formation through multiple molecular targets.

Thin endometrium is associated with the risk of hypertensive disorders of pregnancy in fresh IVF/ICSI embryo transfer cycles: a retrospective cohort study of 9,266 singleton births

BACKGROUND

Thin endometrial thickness (EMT) has been suggested to be associated with reduced incidence of pregnancy rate after in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment, but the effect of thin endometrium on obstetric outcome is less investigated. This study aims to determine whether EMT affects the incidence of obstetric complications in fresh IVF/ICSI-embryo transfer (ET) cycles.

METHODS

We conducted a retrospective cohort study collecting a total of 9266 women who had singleton livebirths after fresh IVF/ICSI-ET treatment cycles at the Center for Reproductive Medicine Affiliated to Shandong University between January 2014 and December 2018. The women were divided into three groups according to the EMT: 544 women with an EMT ≤8 mm, 6234 with an EMT > 8-12 mm, and 2488 with an EMT > 12 mm. The primary outcomes were the incidence of obstetric complications including hypertensive disorders of pregnancy (HDP), gestational diabetes mellitus (GDM), placental abruption, placenta previa, postpartum hemorrhage (PPH) and cesarean section. Multivariable logistic regression analysis was performed to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for associations between the EMT measured on the day of human chorionic gonadotropin (HCG) trigger and the risk of the outcomes of interest.

RESULTS

The HDP incidence rate of pregnant women was highest in EMT ≤ 8 mm group and significantly higher than those in EMT from > 8-12 mm and EMT > 12 mm group, respectively (6.8% versus 3.6 and 3.5%, respectively; P = 0.001). After adjustment for confounding variables by multivariate logistic regression analysis, a thin EMT was still statistically significant associated with an increased risk of HDP. Compared with women with an EMT > 8-12 mm, women with an EMT ≤8 mm had an increased risk of HDP (aOR = 1.853, 95% CI 1.281-2.679, P = 0.001).

CONCLUSION

A thin endometrium (≤8 mm) was found to be associated with an increased risk of HDP after adjustment for confounding variables, indicating that the thin endometrium itself is a risk factor for HDP. Obstetricians should remain aware of the possibility of HDP when women with a thin EMT achieve pregnancy through fresh IVF/ICSI-ET treatment cycles.

MAML1: a coregulator that alters endometrial epithelial cell adhesive capacity

BACKGROUND

Abnormalities in endometrial receptivity has been identified as a major barrier to successful embryo implantation. Endometrial receptivity refers to the conformational and biochemical changes occurring in the endometrial epithelial layer which make it adhesive and receptive to blastocyst attachment. This takes place during the mid-secretory phase of woman's menstrual cycle and is a result of a delicate interplay between numerous hormones, cytokines and other factors. Outside of this window, the endometrium is refractory to an implanting blastocyst. It has been shown that Notch ligands and receptors are dysregulated in the endometrium of infertile women. Mastermind Like Transcriptional Coactivator 1 (MAML1) is a known coactivator of the Notch signaling pathway. This study aimed to determine the role of MAML1 in regulating endometrial receptivity.

METHODS

The expression and localization of MAML1 in the fertile human endometrium (non-receptive proliferative phase versus receptive mid-secretory phase) were determined by immunohistochemistry. Ishikawa cells were used as an endometrial epithelial model to investigate the functional consequences of MAML1 knockdown on endometrial adhesive capacity to HTR8/SVneo (trophoblast cell line) spheroids. After MAML1 knockdown in Ishikawa cells, the expression of endometrial receptivity markers and Notch dependent and independent pathway members were assessed by qPCR. Two-tailed unpaired or paired student's t-test were used for statistical analysis with a significance threshold of P < 0.05.

RESULTS

MAML1 was localized in the luminal epithelium, glandular epithelium and stroma of human endometrium and the increased expression identified in the mid-secretory phase was restricted only to the luminal epithelium (P < 0.05). Functional analysis using Ishikawa cells demonstrated that knockdown of MAML1 significantly reduced epithelial adhesive capacity (P < 0.01) to HTR8/SVneo (trophoblast cell line) spheroids compared to control. MAML1 knockdown significantly affected the expression of classical receptivity markers (SPP1, DPP4) and this response was not directly via hormone receptors. The expression level of Hippo pathway target Ankyrin repeat domain-containing protein 1 (ANKRD1) was also affected after MAML1 knockdown in Ishikawa cells.

CONCLUSION

Our data strongly suggest that MAML1 is involved in regulating the endometrial adhesive capacity and may facilitate embryo attachment, either directly or indirectly through the Notch signaling pathway.

Human Herpesviruses 6A and 6B in Reproductive Diseases

Human herpesviruses 6A (HHV-6A) and human herpesvirus 6B (HHV-6B)—collectively, HHV-6A/B—are recently-discovered but ancient human viruses. The vast majority of people acquire one or both viruses, typically very early in life, producing an ineradicable lifelong infection. The viruses have been linked to several neurological, pulmonary and hematological diseases. In early human history, the viruses on multiple occasions infected a germ cell, and integrated their DNA into a human chromosome. As a result, about 1% of humans are born with the full viral genome present in every cell, with uncertain consequences for health. HHV-6A may play a role in 43% of cases of primary unexplained infertility. Both the inherited and acquired viruses may occasionally trigger several of the factors that are important in the pathogenesis of preeclampsia. Transplacental infection occurs in 1-2% of pregnancies, with some evidence suggesting adverse health consequences for the child. While emerging knowledge about these viruses in reproductive diseases is not sufficient to suggest any changes in current practice, we write this review to indicate the need for further research that could prove practice-changing.

Use of clomiphene citrate protocol for controlled ovarian stimulation impairs endometrial maturity

INTRODUCTION

Despite recent advances in assisted reproduction techniques and recent knowledge regarding embryo and endometrium quality, implantation and birth rates remain low. The objective of this study was to investigate whether clomiphene citrate alters endometrial maturation in infertile patients.

METHODS

In a prospective self-matched cohort study, we assessed the ovulation of women in spontaneous and stimulated cycles (with clomiphene citrate). We determined the ovulation day by ultrasound scanning. In both cycles, we took four blood samples (BS1 - at early proliferative phase, BS2 - at mid proliferative phase, BS3 - after ovulation and BS4 - at mid luteal phase) to determine the serum concentrations of FSH, LH, estradiol and progesterone. We retrieved an endometrial biopsy five days after ovulation, followed by blinded analysis and classification according to Noyes criteria, in both cycles.

RESULTS

Twenty-two participants completed the study. There were significant differences in FSH BS3 (p=0.001), in LH BS3 and BS4 (p<0.001 and p=0.049, respectively), in estradiol BS2, BS3 and BS4 (p<0.001, p=0.024 and p<0.001, respectively) and in progesterone BS3 and BS4 (p=0.028 and p<0.001, respectively). Considering Noyes criteria, there was a one-day delay when comparing the stimulated cycle with the spontaneous cycle (p=0.004), and a two-day delay when comparing the stimulated cycle with the biopsy day.

CONCLUSION

This study indicates that ovarian stimulation with clomiphene citrate delays the endometrial maturity, and could possibly impair the implantation process due to asynchrony.

Deficiency of Sirtuin 1 Impedes Endometrial Decidualization in Recurrent Implantation Failure Patients

Decidualization is driven by differentiation of human endometrial stromal cells (ESCs), and is a prerequisite for successful implantation and establishment of pregnancy. The critical role of impaired decidualization in women suffered recurrent implantation failure (RIF) has been established, while the underlying mechanism is poorly understood. In the present study, we verified the essential role of Sirtuin1 (SIRT1) in regulating differentiation and maintaining reactive oxygen species (ROS) homeostasis of human ESCs during decidualization. The abundance of SIRT1 was decreased in RIF patients both in the endometria during window of implantation phase and in the decidualized ESCs. Downregulation of SIRT1 disrupted the intracellular ROS homeostasis during decidualization of ESC, manifested as the accumulation of intracellular ROS level and the reduction of antioxidant stress molecules. Elimination of ROS with N-acetyl-L-cysteine (NAC) could rescued the decidualization inhibition caused by SIRT1 knockdown. Further, we explored the insufficient expression of SIRT1 in ESC affected the deacetylation of forkhead box O1 (FOXO1), and thus inhibited the transcriptional activity of FOXO1. This could account for the dysregulation of intracellular ROS homeostasis during decidualization and decreased expression of decidual markers. Collectively, our findings provided insight into the role of down-regulated SIRT1 in the poor decidual response of ESCs in RIF patients.

Current and Future Roles of Circular RNAs in Normal and Pathological Endometrium

The uterine endometrium, which lines the mammalian uterus, is essential for embryo implantation. This lining undergoes significant changes during sexual and menstrual cycles. The endometrium is also associated with hormone-related diseases such as endometriosis and endometrial cancer. Circular RNAs (circRNAs) play a role in various biological processes. Recent studies have determined that circRNAs function in both normal and pathological endometrial environments. Here, we review high-throughput studies pertaining to circRNAs as well as individual circRNAs active in the endometrium, in order to explore the myriad functions of circRNAs in the endometrium and mechanisms underlying these functions, from panoramic and individual perspectives. Owing to their abundant expression, stability, and small size, circRNAs have displayed potential usefulness as diagnostic markers and treatment targets for endometrial-related diseases. Therefore, the specific role of circRNAs in the endometrium warrants systematic investigation in the future.

Customized Frozen Embryo Transfer after Identification of the Receptivity Window with a Transcriptomic Approach Improves the Implantation and Live Birth Rates in Patients with Repeated Implantation Failure

The aim of this prospective study was to evaluate outcome benefits expected in repeated implantation failure (RIF) patients (n = 217) after customized embryo transfer based upon identification of the receptivity window by transcriptomic approach using the Win-Test. In this test, the expression of 11 endometrial genes known to be predictive of endometrial receptivity is assessed by RT-PCR in biopsies collected during the implantation window (6-9 days after the spontaneous luteinizing hormone surge during natural cycles, 5-9 days after progesterone administration during hormone replacement therapy cycles). Then, patients underwent either customized embryo transfer (cET, n = 157 patients) according to the Win-Test results or embryo transfer according to the classical procedure (control group, n = 60). Pregnancy and live birth rates were compared in the two groups. The Win-Test showed that in 78.5% of women, the receptivity window lasted less than 48 h, although it could be shorter (< 24 h, 9.5%) or longer (> 48 h, 12%). This highlighted that only in 20% of patients with RIF the endometrium would have been receptive if the classical embryo transfer protocol was followed. In the other 80% of patients, the receptivity window was delayed by 1-3 days relative to the classical timing. This suggests that implantation failure could be linked to inadequate timing of embryo transfer. In agreement, both implantation (22.7% vs. 7.2%) and live birth rates per patient (31.8% vs. 8.3%) were significantly higher in the cET group than in the control group. cET on the basis of the Win-Test results could be proposed to improve pregnancy and live birth rates.ClinicalTrials.gov ID: NCT04192396; December 5, 2019, retrospectively registered.

Identifying biomarkers for predicting successful embryo implantation: applying single to multi-OMICs to improve reproductive outcomes

BACKGROUND

Successful embryo implantation is a complex process that requires the coordination of a series of events, involving both the embryo and the maternal endometrium. Key to this process is the intricate cascade of molecular mechanisms regulated by endocrine, paracrine and autocrine modulators of embryonic and maternal origin. Despite significant progress in ART, implantation failure still affects numerous infertile couples worldwide and fewer than 10% of embryos successfully implant. Improved selection of both the viable embryos and the optimal endometrial phenotype for transfer remains crucial to enhancing implantation chances. However, both classical morphological embryo selection and new strategies incorporated into clinical practice, such as embryonic genetic analysis, morphokinetics or ultrasound endometrial dating, remain insufficient to predict successful implantation. Additionally, no techniques are widely applied to analyse molecular signals involved in the embryo-uterine interaction. More reliable biological markers to predict embryo and uterine reproductive competence are needed to improve pregnancy outcomes. Recent years have seen a trend towards 'omics' methods, which enable the assessment of complete endometrial and embryonic molecular profiles during implantation. Omics have advanced our knowledge of the implantation process, identifying potential but rarely implemented biomarkers of successful implantation.

OBJECTIVE AND RATIONALE

Differences between the findings of published omics studies, and perhaps because embryonic and endometrial molecular signatures were often not investigated jointly, have prevented firm conclusions being reached. A timely review summarizing omics studies on the molecular determinants of human implantation in both the embryo and the endometrium will help facilitate integrative and reliable omics approaches to enhance ART outcomes.

SEARCH METHODS

In order to provide a comprehensive review of the literature published up to September 2019, Medline databases were searched using keywords pertaining to omics, including 'transcriptome', 'proteome', 'secretome', 'metabolome' and 'expression profiles', combined with terms related to implantation, such as 'endometrial receptivity', 'embryo viability' and 'embryo implantation'. No language restrictions were imposed. References from articles were also used for additional literature.

OUTCOMES

Here we provide a complete summary of the major achievements in human implantation research supplied by omics approaches, highlighting their potential to improve reproductive outcomes while fully elucidating the implantation mechanism. The review highlights the existence of discrepancies among the postulated biomarkers from studies on embryo viability or endometrial receptivity, even using the same omic analysis.

WIDER IMPLICATIONS

Despite the huge amount of biomarker information provided by omics, we still do not have enough evidence to link data from all omics with an implantation outcome. However, in the foreseeable future, application of minimally or non-invasive omics tools, together with a more integrative interpretation of uniformly collected data, will help to overcome the difficulties for clinical implementation of omics tools. Omics assays of the embryo and endometrium are being proposed or already being used as diagnostic tools for personalised single-embryo transfer in the most favourable endometrial environment, avoiding the risk of multiple pregnancies and ensuring better pregnancy rates.

Ultradian rhythms in heart rate variability and distal body temperature anticipate onset of the luteinizing hormone surge

The menstrual cycle is characterized by predictable patterns of physiological change across timescales. Although patterns of reproductive hormones across the menstrual cycle, particularly ultradian rhythms, are well described, monitoring these measures repeatedly to predict the preovulatory luteinizing hormone (LH) surge is not practical. In the present study, we explored whether non-invasive measures coupled to the reproductive system: high frequency distal body temperature (DBT), sleeping heart rate (HR), sleeping heart rate variability (HRV), and sleep timing, could be used to anticipate the preovulatory LH surge in women. To test this possibility, we used signal processing to examine these measures in 45 premenopausal and 10 perimenopausal cycles alongside dates of supra-surge threshold LH and menstruation. Additionally, urinary estradiol and progesterone metabolites were measured daily surrounding the LH surge in 20 cycles. Wavelet analysis revealed a consistent pattern of DBT and HRV ultradian rhythm (2-5 h) power that uniquely enabled anticipation of the LH surge at least 2 days prior to its onset in 100% of individuals. Together, the present findings reveal fluctuations in distal body temperature and heart rate variability that consistently anticipate the LH surge, suggesting that automated ultradian rhythm monitoring may provide a novel and convenient method for non-invasive fertility assessment.

Live birth rate from euploid blastocysts is not associated with infertility etiology or oocyte source following frozen-thawed embryo transfer (FET): analysis of 4148 cycles reported to SART CORS

PURPOSE

To investigate whether live birth rates from euploid blastocyst frozen-thawed embryo transfer (FET) cycles are associated with infertility diagnosis or oocyte source.

DESIGN

Retrospective analysis of FET cycles reported to SART CORS in 2014.

METHODS

Data from fresh IVF cycles with preimplantation genetic testing for aneuploidy (PGT-A), linked to the first FET cycles, were collected from the 2014 SART CORS database for autologous and donor oocyte cycles. Inclusion criteria were patients undergoing FET with euploid embryos (n = 4148). Demographic data including age, BMI, prior fertility, and etiology of infertility were collected from the retrieval cycle and analyzed. Patients with uterine anomalies, preimplantation genetic testing-mutation (PGT-M) for genetic diseases, gender selection, HLA determination, or systemic and immunologic disorders were excluded. The primary outcome measure was live birth (LB) rate. Potential confounders such as age, prior fertility, and maximum baseline FSH values were analyzed with regression models as indicated.

RESULTS

Though age, maximum baseline FSH, and infertility diagnosis were significantly different, LB was similar between patients undergoing autologous or donor oocyte FET cycles. Etiology of infertility was not significantly associated with LB in autologous cycles (p = 0.95). Potential confounders such as maternal age, prior fertility, and maximum baseline FSH were not associated with outcomes; however, maternal BMI was inversely related to LB in autologous cycles, with an odds ratio of 0.97 (95% CI: 0.96-0.98 (rho = - 0.08, p < 0.01)).

CONCLUSIONS

After controlling for confounding variables, a euploid embryo derived from a donor or autologous oocyte results in similar LB in women with different infertility diagnoses.

BCL-6 Overexpression as a Predictor for Endometriosis in Patients Undergoing In Vitro Fertilization

OBJECTIVE

To evaluate the positive predictive value (PPV) of endometrial BCL-6 overexpression as a noninvasive screening test endometriosis in patients undergoing in vitro fertilization (IVF).

METHODS

Retrospective cohort study at a university-affiliated private practice. Inclusion criteria were reproductive age females currently undergoing IVF with a diagnosis of unexplained infertility or unexplained recurrent pregnancy loss. Those with endometrial BCL-6 overexpression underwent laparoscopic surgery with an indication for treatment of suspected endometriosis. The primary outcome was the PPV of endometrial BCL-6 testing to surgically diagnose endometriosis. Statistical analysis was performed using SPSS v.25.0.

RESULTS

Seventy-five patients met inclusion criteria for our study. The PPV of BCL-6 testing for endometriosis was 96%. Of those patients without endometriosis, 100% had other inflammatory pelvic pathologies, which were diagnosed and treated at the time of laparoscopy.

CONCLUSIONS

Endometrial BCL-6 overexpression has a high PPV for diagnosing endometriosis and can help identify a patient population that may require surgical treatment before embryo transfer.

Determining the Molecular Background of Endometrial Receptivity in Adenomyosis

Background: Adenomyosis is a gynaecological condition with limited evidence of negative impact to endometrial receptivity. It is commonly associated with endometriosis, which has been shown to alter endometrial expression patterns. Therefore, the candidate genes identified in endometriosis could serve as a source to study endometrial function in adenomyosis. Methods: Transcripts/proteins associated with endometrial receptivity in women with adenomyosis or endometriosis and healthy women were obtained from publications and their nomenclature was adopted according to the HUGO Gene Nomenclature Committee (HGNC). Retrieved genes were analysed for enriched pathways using Cytoscape/Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and Reactome tools to prioritise candidates for endometrial receptivity. These were used for validation on women with (n = 9) and without (n = 13) adenomyosis. Results: Functional enrichment analysis of 173, 42 and 151 genes associated with endometriosis, adenomyosis and healthy women, respectively, revealed signalling by interleukins and interleukin-4 and interleukin-13 signalling pathways, from which annotated LIF, JUNB, IL6, FOS, IL10 and SOCS3 were prioritised. Selected genes showed downregulated expression levels in adenomyosis compared to the control group, but without statistical significance. Conclusion: This is the first integrative study providing putative candidate genes and pathways characterising endometrial receptivity in women with adenomyosis in comparison to healthy women and women with endometriosis.

Human Endometrial Stromal Cell Differentiation is Stimulated by PPARβ/δ Activation: New Targets for Infertility?

CONTEXT

Implantation is a reproductive bottleneck in women, regulated by fluctuations in ovarian steroid hormone concentrations. However, other nuclear receptor ligands are modifiers of endometrial differentiation leading to successful pregnancy. In the present study we analyzed the effects of peroxisome-proliferator-activated receptor β/δ (PPARβ/δ) activation on established cellular biomarkers of human endometrial differentiation (decidualization).

OBJECTIVE

The objective of this work is to test the effects of PPARβ/δ ligation on human endometrial cell differentiation.

DESIGN

Isolated primary human endometrial stromal cells (ESCs) were treated with synthetic (GW0742) or natural (all trans-retinoic acid, RA) ligands of PPARβ/δ, and also with receptor antagonists (GSK0660, PT-S58, and ST247) in the absence or presence of decidualizing hormones (10 nM estradiol, 100 nM progesterone, and 0.5 mM dibutyryl cAMP [3',5'-cyclic adenosine 5'-monophosphate]). In some cases interleukin (IL)-1β was used as an inflammatory stimulus. Time course and dose-response relationships were evaluated to determine effects on panels of well characterized in vitro biomarkers of decidualization.

RESULTS

PPARβ/δ, along with estrogen receptor α (ERα) and PR-A and PR-B, were expressed in human endometrial tissue and isolated ESCs. GW0742 treatment enhanced hormone-mediated ESC decidualization in vitro as manifested by upregulation of prolactin, insulin-like growth factor-binding protein 1, IL-11, and vascular endothelial growth factor (VEGF) secretion and also increased expression of ERα, PR-A and PR-B, and connexin 43 (Cx43). RA treatment also increased VEGF, ERα, PR-A, and PR-B and an active, nonphosphorylated isoform of Cx43. IL-1β and PPARβ/δ antagonists inhibited biomarkers of endometrial differentiation.

CONCLUSION

Ligands that activate PPARβ/δ augment the in vitro expression of biomarkers of ESC decidualization. By contrast, PPARβ/δ antagonists impaired decidualization markers. Drugs activating these receptors may have therapeutic benefits for embryonic implantation.

Expression of Pinopodes in the Endometrium from Recurrent Pregnancy Loss Women. Role of Thrombomodulin and Ezrin

BACKGROUND

Pinopode expression has been suggested as a marker of endometrial receptivity.

METHODS

We set up an experimental study comparing endometrial tissue from recurrent pregnancy loss (RPL, n = 30) and fertile control (CTR, n = 20) women in terms of pinopode expression/morphology; expression of thrombomodulin (TM) and ezrin; cytoskeletal organization. Endometrial samples were collected during implantation window and evaluated by scanning electron microscopy, western blot, and immunofluorescence.

RESULTS

We found that RPL endometrial tissue showed: (i) increased pinopodes density (* p < 0.05); (ii) a reduced diameter of pinopodes (* p < 0.05); (iii) a decreased TM and ezrin expression (p < 0.05). Additionally, confocal images showed a significantly reduced expression of phosphorylated (p)-ezrin, confirming the results obtained through immunoblot analysis. Immunofluorescence staining showed that in CTR samples, junctions between cells are intact and clearly visible, whereas actin filaments appear completely lost in RPL endometrial samples; this suggests that, due to the impaired expression and activity of TM and ezrin, actin does not bind to plasma membrane in order to orchestrate the cytoskeletal actin filaments.

CONCLUSIONS

Our findings suggest that an impaired expression of TM and expression/activation of ezrin may affect the connection between the TM and actin cytoskeleton, impairing the organization of cytoskeleton and, eventually, the adequate pinopode development.

Endometrial receptivity and pregnancy outcome

Human implantation is a highly complex and multifactorial process. Successful implantation requires the presence of a healthy embryo, a receptive endometrium, and a synchronized molecular dialogue between the two, as well as immune tolerance/protection from the host. The endometrial receptivity refers to a hormonally limited period in which the endometrial tissue acquires a transient functional status allowing blastocyst implantation and pregnancy initiation. Global knowledge of endometrial receptivity grew up in recent years. Improvements in genetics, new biomarkers, noninvasive methods, new advanced techniques (Endometrial receptivity assay - the ERA system, proteomic analysis) offer the possibility to evaluate the endometrial status and to manage patients with infertility problems, especially women undergoing assisted reproductive treatment. This overview reports the most relevant knowledge and recent advances in the study of implantation processes from the perspective of the endometrium, often considered as being the main barrier for a successful pregnancy initiation. Endometrial receptivity is a topic of great interest and further studies are needed for the early identification of endometrial abnormalities and the discovery of new strategies for increasing the chance for the establishment of pregnancy.

Analysis of the guidance value of 3D ultrasound in evaluating endometrial receptivity for frozen-thawed embryo transfer in patients with repeated implantation failure

Background

Repeated implantation failure (RIF) is currently believed by some scholars to be mainly related to the poor endometrial receptivity. Three-dimensional (3D) ultrasound, as a noninvasive examination, has attracted the most attention. This paper further discusses whether 3D ultrasound of the endometrial receptivity index has guidance value in the evaluation of pregnancy outcomes in patients with RIF following frozen-thawed embryo transfer.

Methods

A total of 79 patients with RIF were retrospectively analyzed. These 79 patients which were confirmed by the transvaginal ultrasonography detection comprised 36 cases of intrauterine pregnancy, which were included in the pregnancy group, and 43 cases with biochemical pregnancy (the HCG in blood or urine is only transient and can be detected by clinical biochemical methods. The pregnancy sac cannot be seen under ultrasound) or negative results of human chorionic gonadotropin (HCG) examination, which were included in the non-pregnancy group. The endometrial thickness, uterine volume, sub-endometrial blood flow type, pulsatility index (PI) and resistance index (RI) of the spiral artery; the RI and PI of the uterine artery; and the peak systolic velocity/end diastolic velocity (S/D) of the two groups were measured and analyzed.

Results

(I) There were no significant differences in the age, infertility years, body mass index (BMI), anti-Müllerian hormone (AMH), endometrial thickness on the hCG injection day, estradiol (E2), and progesterone (P) between the pregnant and non-pregnant groups (P>0.05). (II) There were no significant differences in the endometrial thickness, uterine volume, and RI and PI of the uterine artery on the day before the implantation between the two groups (P>0.05). (III) There was statistical difference in the sum of the S/D of the two uterine arteries between the two groups (P<0.05) with a cutoff value of 14.47 (P<0.05). (IV) The RI and PI of the spiral artery in the non-pregnancy group were lower than those in the pregnancy group, and the difference was statistically significant (P<0.05). (V) The differences in the endometrial classification and subendometrial blood flow classification between the two groups were statistically significant (P<0.05).

Conclusions

Ultrasonographic endometrial blood flow classification, spiral artery blood flow parameters, and uterine artery blood flow parameters can be effective indexes for evaluating endometrial receptivity, and they have a certain clinical significance in evaluating the pregnancy outcome of RIF patients after retransplantation.

Pathophysiological Basis of Endometriosis-Linked Stress Associated with Pain and Infertility: A Conceptual Review

Women with endometriosis are often under stress due to the associated pain, infertility, inflammation-related and other comorbidities including cancer. Additionally, these women are also under stress due to taboos, myths, inter-personal troubles surrounding infertility and pain of the disease as well as due to frequent incidences of missed diagnosis and treatment recurrence. Often these women suffer from frustration and loss of valuable time in the prime phase of life. All these complexities integral to endometriosis posit a hyperstructure of integrative stress physiology with overt differentials in effective allostatic state in women with disease compared with disease-free women. In the present review, we aim to critically examine various aspects of pathophysiological basis of stress surrounding endometriosis with special emphasis on pain and subfertility that are known to affect the overall health and quality of life of women with the disease and promising pathophysiological basis for its effective management.

Fecundity disorders in older women: declines in follicular development and endometrial receptivity

Background

Little research is available on follicular development and endometrial receptivity in older women. This study aimed to assess follicular development and endometrial receptivity, and to evaluate ultrasonic parameters in predicting endometrial receptivity during the implantation window in older women.

Methods

For this prospective case-control study, 224 older women and 215 young women were recruited. The follicular development and endometrial thickness were monitored by transvaginal ultrasound. During the implantation window, the pulsatility index (PI) and resistance index (RI) of the uterine arteries and subendometrial region, endometrial volume, vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were calculated between the two groups. The ultrasonic parameters were used to assess endometrial receptivity in older women.

Results

The serum anti-Mullerian hormone (AMH) concentration and antral follicle count (AFC) were significantly lower in older women than in young women. The average diameter of the dominant follicle on days 14, 16, and 18 of the menstrual cycle were significantly smaller, and the subendometrial region RI on days 12, 14, 16, and 18 of the menstrual cycle were significantly higher in older women than in young women. The normal ovulation rate was significantly lower in older women than in young women. The subendometrial region RI was significantly higher, and the endometrial VI, FI, and VFI were significantly lower in older women compared with young women. The biochemical pregnancy rate, clinical pregnancy rate and ongoing pregnancy rate of older women were significantly lower than in young women. The best ultrasonic parameter for predicting endometrial receptivity during the implantation window in older women was VI (AUC =0.889, sensitivity 92.6% and specificity 85.4%).

Conclusions

Older women present decreased serum AMH concentrations and AFC, defined as indicators of ovarian reserve function. Older women are characterized by decreased follicular development and endometrial receptivity, which may lead to fecundity disorders.

Does a hyperechogenic endometrial mass in the uterus during controlled ovarian stimulation affect assisted reproductive technology cycle outcomes?

OBJECTIVES

Healthy embryos and endometrial receptivity are keys to the success of in-vitro fertilization and embryo transfer (IVF-ET). Abnormal transvaginal ultrasonography (TVU) findings in the endometrium are a concern during assisted reproductive technology (ART) treatments. Observation of a hyperechogenic endometrial mass (HEM) during controlled ovarian stimulation (COS) in an IVF or intracytoplasmic sperm injection (ICSI) cycle is a dilemma. Here we investigated whether an HEM would affect ART cycle outcomes.

STUDY DESIGN

We analyzed all data from patients who underwent IVF or ICSI treatment cycles from January 1, 2009 to December 31, 2016 at our institution. Patients diagnosed with an HEM were included. Each woman was matched with two control subjects of similar age (± 1 year), in terms of the number of cycles, type of infertility (primary or secondary), protocol used for COS, but with no HEM identified by TVU. Baseline characteristics, COS response, and pregnancy outcomes after ET were compared.

RESULTS

In all, 1088 patients were diagnosed with an HEM. Of these, 426 met the inclusion criteria and were matched with 852 controls. Baseline characteristics showed no significant differences between the groups. The peak endometrial thickness was significantly greater in the experimental group than in the control group (1.15 ± 0.18 cm vs. 1.08 ± 0.21 cm, p < 0.001). The live birth rates were 43.7% vs 46.2% in the experimental and control groups, respectively. There were no significant between-group differences in the rates of biochemical or clinical pregnancy or abortions at any stage.

CONCLUSIONS

Newly diagnosed HEMs < 18 mm in diameter monitored by TVU did not impair the outcomes of ART following COS in this study. If other conditions are suitable, completion of ART cycles should be the appropriate approach in such cases.

KEY MESSAGE

Newly diagnosed hyperechogenic endometrial masses measuring <18 mm in diameter monitored by TVU during COS did not adversely affect the outcomes of these IVF/ICSI-ET cycles.

Frozen IVF Cycles to Circumvent the Hormonal Storm on Endometrium

Controlled ovarian hyperstimulation (COH) determines an anticipation of endometrial maturation and a premature occurrence of the implantation window, as shown by histological, histochemical, and molecular studies and indirectly by clinical trials. There is growing agreement that in patients hyper-responding to COH and in those undergoing transfer at the blastocyst stage, deferring the transfer in a subsequent frozen cycle could increase pregnancy outcomes. For blastocysts, implantation after a fresh transfer may be limited as the implantation window is already closed while, in hyper-responders to COH, the anticipation magnitude could be more marked thus hampering implantation also for cleavage-stage embryos. Research should focus in depth on pregnancy outcomes and on the most suitable modality to prepare the endometrium for frozen transfers.

Diagnostic and therapeutic options in recurrent implantation failure

Recurrent implantation failure (RIF) is an uncommon, imprecisely defined clinical disorder characterized by failure to achieve pregnancy after repeated embryo transfers. The diverse etiologies and incomplete understanding of RIF provide significant diagnostic and therapeutic challenges to patients and providers. Careful clinical evaluation prior to assisted reproduction can uncover many treatable causes, including thyroid dysfunction, submucosal myomas, and tobacco use. The more-subtle causes often require a more-targeted assessment. Undetected, small polyps or small areas of intrauterine synechiae are relatively common and easily treated contributors to RIF. Molecular and cellular abnormalities pose a greater therapeutic challenge. Putative causes of RIF, including progesterone resistance, shifted window of receptivity, decreased integrin expression, and immunologic disturbances, should be considered in the evaluation of a patient with otherwise unexplained RIF. It may also be true that a more complex and standardized definition of RIF would be helpful in these cases. In this paper, we review the diagnostic and therapeutic approaches to RIF, with emphasis on disorders of endometrial receptivity.

Physiologic Events of Embryo Implantation and Decidualization in Human and Non-Human Primates

Reproduction is a fundamental process for the preservation of the human species. This process requires a sequence of orchestrated events that are necessary for a successful pregnancy. Two of the most critical steps in the establishment of human pregnancy are implantation and decidualization, which are required for maternal interactions with the developing embryo. This review primarily highlights the physiological aspects of these two events and the adverse pregnancy outcomes from defective implantation and decidualization. The focus of this review is to provide a general concept of the mechanisms involved during the window of implantation, description of components involved in the process and possible pathologies that could disrupt the embryo implantation and decidualization and specifically as it applies to women and non-human primates.

The impact of hyaluronan-enriched culture medium and intrauterine infusion of human chorionic gonadotropin on clinical outcomes in blastocyst transfer cycles

Over the last few decades, advances in ovarian hormonal stimulation, embryology laboratory technologies and embryo genetic testing, have significantly enhanced clinical outcomes in human assisted reproduction technologies (ART). However, embryo implantation remains a major bottleneck in achieving better pregnancy and live birth rates. Thus, there is growing interest in establishing new approaches to enhance implantation efficiency after embryo transfer. With advanced molecular techniques, many promising biomarkers associated with embryonic and endometrial changes occurring prior to and during embryo implantation have been identified. However, despite the progress in applying novel procedures into IVF practice, clinical evaluation of those biomarkers has so far reached modest predictive value for enhancing blastocyst developmental potential and endometrial receptivity. Therefore, other simpler strategies have also been introduced to increase the rates of successful clinical pregnancies and live births. One of these approaches is to investigate the impact of using embryo transfer medium containing high concentrations of an adherence compound, such as hyaluronic acid (HA), on IVF outcomes. Additionally, intrauterine infusion of a small volume of human chorionic gonadotropin (hCG) at the time of embryo transfer (ET) has also been proposed as a technique that might be advantageous for increasing the clinical outcomes, considering the fact that hCG plays a critical role in synchronizing endometrial and fetal development. However, the current findings from both interventions remain controversial, demonstrating a mixture of positive and indifferent results of these treatments in ART cycles. Further research will be crucial for a better understanding of the molecular mechanism of cross-talk between the blastocyst and the maternal endometrium during the optimal implantation period when using either hyaluronan-enriched medium or hCG infusion before embryo transfers. Therefore, this review aims to present existing literature related to both treatments, emphasizing their effects on blastocyst implantation.Abbreviations: ART: assisted reproduction technologies; HA: hyaluronic acid; hCG: human chorionic gonadotrophin; IVF: in vitro Fertilization; ET: embryo transfer; pH: hydrogen ions; CO2: Carbone dioxide; O2: Oxygen; PGT: pre-implantation genetic testing; FET: frozen embryo transfer; PCOS: Polycystic ovarian syndrome; DNA: deoxyribonucleic acid; miRNA: micro-ribonucleic acid; EVs: extracellular vesicles; ERA: endometrial receptivity array; CD44 and RHAMM: primary hyaluronan surface receptors; RCT: randomized clinical trials; LBR: life birth rate; CPR: clinical pregnancy rate; IR: implantation rate.

Comprehensive analysis of the associations between previous pregnancy failures and blastocyst aneuploidy as well as pregnancy outcomes after PGT-A

PURPOSE

To investigate the associations of previous pregnancy failures, including implantation failures (IFs), biochemical pregnancy losses (BPLs), and early (EMs) and late miscarriages (LMs), with blastocyst aneuploidy and pregnancy outcomes after PGT-A.

METHODS

This study included 792 couples who underwent PGT-A after multiple pregnancy failures. Subgroup analyses were used to compare the blastocyst aneuploidy rate (BAR), implantation rate (IR), early miscarriage rate (EMR), and live birth rate (LBR). Multiple linear and logistic regression models were used to evaluate the associations. The control group comprised couples with ≤ 2 IFs, ≤ 1 BPL, ≤ 1 EM, and no LM.

RESULTS

Notably, a history of ≥ 4 IFs was significantly associated with an increase in aneuploid blastocysts (42.86% vs. 33.05%, P = 0.044, B = 10.23 for 4 IFs; 48.80% vs. 33.05%, P = 0.002, B = 14.43 for ≥ 5 IFs). Women with ≥ 4 prior EMs also harbored more aneuploid blastocysts (41.00% vs. 33.05%, P = 0.048; B = 9.23). Compared with the control group, women with ≥ 4 prior EMs had a significantly higher EMR (6.58% vs. 31.11%, P < 0.001, OR = 6.49) and a lower LBR (53.49% vs. 34.18%, P = 0.007, OR = 0.56) after euploid transfer. Moreover, a history of LM(s) was associated with adverse pregnancy outcomes after PGT-A (OR for EM = 3.16; OR for live birth = 0.48). However, previous BPLs and 2 EMs were not associated significantly with blastocyst aneuploidy and pregnancy outcomes after PGT-A.

CONCLUSION

A history of high-order IFs or EMs and existence of LM(s) were significantly associated with blastocyst aneuploidy and adverse pregnancy outcomes after PGT-A, whereas no such associations were observed with BPLs or 2 EMs.

Letrozole Versus Clomiphene Citrate and Natural Cycle: Endometrial Receptivity During Implantation Window in Women With Polycystic Ovary Syndrome

OBJECTIVE

Numerous studies have reported on ovulation and pregnancy rates in patients with polycystic ovary syndrome (PCOS). However, relevant data on endometrial receptivity are limited. This study was conducted to compare endometrial receptivity during implantation windows among letrozole (LE), clomiphene citrate (CC), and natural cycle, and to assess the predictive value for pregnancy of observed indicators.

METHODS

This randomized controlled trial study enrolled 270 patients with PCOS. Patients were given LE (n=90) at a dose of 2.5mg/day or CC (n=90) at a dose of 50 mg/day on cycle days 5-9 for ovulation induction. Patients in the natural cycle group (n=90) did not receive any drug for ovulation induction. Endometrial ultrasonic parameters, integrin αvβ3, and vascular endothelial growth factor (VEGF) concentrations in uterine secretion were detected during the implantation window. The endometrial receptivity, ovulation rate, pregnancy rates, and predictive value of observed indicators for pregnancy were analyzed.

RESULTS

The successful ovulation rate did not differ between the LE group and CC group (P>0.05). Endometrial ultrasonic parameters [endometrial thickness (ET), endometrial volume (EV), vascularization index (VI), flow index (FI), vascularization flow index (VFI)], integrin αvβ3, and VEGF concentrations in uterine fluid were significantly higher in the LE group compared with the CC group and natural cycle group (P<0.05). The clinical pregnancy and ongoing pregnancy rates of the LE group were significantly higher than in the CC group (P<0.05). Endometrial ultrasonic parameters (VI, FI, and VFI), integrin αvβ3, and VEGF concentrations in uterine fluid of all pregnancy groups were significantly higher compared with the no pregnancy group (P<0.05), and the above parameters in ongoing pregnancy were significantly higher than in biochemical pregnancy (P<0.05). The endometrial FI during the implantation window had the highest predictive value for pregnancy (AUC=0.889). The integrin αvβ3 in uterine fluid had better predictive value (AUC=0.876) than VEGF.

CONCLUSIONS

Endometrial receptivity during the implantation window of LE is superior to CC in PCOS women, which may be related to higher clinical pregnancy and ongoing pregnancy rates. Endometrial FI examined by 3-D power Doppler, and integrin αvβ3 in uterine secretion during the implantation window, could be preferable non-invasive predictor markers for pregnancy.

CLINICAL TRIAL REGISTRATION

www.chictr.org.cn, ChiCTR1900023423.

Efficacy and safety of platelet-rich plasma for the treatment of thin endometrium: A protocol for systematic review and meta-analysis

BACKGROUND

Endometrial thickness has been identified as a prognostic factor for pregnancy rate for patients with female infertility. Thin endometrium is defined as <7 mm on the day of ovulation, or on the day of human chorionic gonadotrophin (HCG) injection in fresh in vitro fertilization (IVF) cycles, or the day to start progesterone in frozen-thaw embryo transfer cycles, as stated in the guideline of thin endometrium from the Canadin Fertility and Andrology Society and Chinese expert consensus from the Society of Reproductive Medicine, Chinese Medical Association. Many medicines are used for improving the endometrial thickness and embryo implantation rate of the patients with thin endometirum, but thin endometrium remains a major troublesome clinical problem with limited efficacy.Platelet-rich plasma (PRP), as a growing and robust therapeutic option in musculoskeletal medicine, is a preparation of autologous plasma with a high concentration of platelets, and the therapeutic mechanism is based on the capacity to supply supra physiologic amounts of essential growth factors to provide a regenerative stimulus for promoting repair in tissues with low healing potential. Some randomized controlled trials have reported the application of PRP for patients with thin endometrium with satisfactory effect. However, there is no systematic review on efficacy and safety of PRP as a treatment of thin endometrium.

METHODS

The data and information will be retrieved from the databases of MEDLINE, Embase, Web of Science, Clinicaltrials.org., Cochrane Library, China Biology Medicine Database, Wan Fang Database, China National Knowledge Infrastructure Database, VIP Science Technology Periodical Database, and OpenGrey for gray literature. The randomized controlled clinical trials are going to be selected before December 20, 2019, in English or Chinese language, with the search terms including "thin endometrium,""platelet-rich plasma," "endometrial thickness," "hemorheology of endometrium," "pregnancy rate," and "adverse reactions." RevMan 5.3 will be used for systematic review and meta-analysis. This protocol will be reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) statement, and the systematic review will be reported with the PRISMA statement.

RESULTS AND CONCLUSION

The efficacy and safety of PRP for the treatment of thin endometrium will be evaluated, and the conclusion will be published to provide medical evidence for a better clinical decision of patients with thin endometirum.

Alterations in Epithelial Cell Polarity During Endometrial Receptivity: A Systematic Review

BACKGROUND

Abnormal endometrial receptivity is one of the major causes of embryo implantation failure and infertility. The plasma membrane transformation (PMT) describes the collective morphological and molecular alterations occurring to the endometrial luminal epithelium across the mid-secretory phase of the menstrual cycle to facilitate implantation. Dysregulation of this process directly affects endometrial receptivity and implantation. Multiple parallels between these alterations to confer endometrial receptivity in women have been drawn to those seen during the epithelial-mesenchymal transition (EMT) in tumorigenesis. Understanding these similarities and differences will improve our knowledge of implantation biology, and may provide novel therapeutic targets to manage implantation failure.

METHODS

A systematic review was performed using the Medline (Ovid), Embase, and Web of Science databases without additional limits. The search terms used were "(plasma membrane* or cell membrane*) and transformation*" and "endometrium or endometrial." Research studies on the PMT or its regulation in women, discussing either the endometrial epithelium, decidualized stroma, or both, were eligible for inclusion.

RESULTS

A total of 198 articles were identified. Data were extracted from 15 studies that matched the inclusion criteria. Collectively, these included studies confirmed the alterations occurring to the endometrial luminal epithelium during the PMT are similar to those seen during the EMT. Such similarities included alterations to the actin cytoskeleton remodeling of adherens junctions, integrin expression and epithelial-stromal communication. These were also some differences between these processes, such as the regulation of tight junctions and mucins, which need to be further researched.

CONCLUSIONS

This review raised the prospect of shared and distinct mechanisms existing in PMT and EMT. Further investigation into similarities between the PMT in the endometrium and the EMT in tumorigenesis may provide new mechanistic insights into PMT and new targets for the management of implantation failure and infertility.

Development and utilization of human decidualization reporter cell line uncovers new modulators of female fertility

Failure of embryo implantation accounts for a significant percentage of female infertility. Exquisitely coordinated molecular programs govern the interaction between the competent blastocyst and the receptive uterus. Decidualization, the rapid proliferation and differentiation of endometrial stromal cells into decidual cells, is required for implantation. Decidualization defects can cause poor placentation, intrauterine growth restriction, and early parturition leading to preterm birth. Decidualization has not yet been systematically studied at the genetic level due to the lack of a suitable high-throughput screening tool. Herein we describe the generation of an immortalized human endometrial stromal cell line that uses yellow fluorescent protein under the control of the prolactin promoter as a quantifiable visual readout of the decidualization response (hESC-PRLY cells). Using this cell line, we performed a genome-wide siRNA library screen, as well as a screen of 910 small molecules, to identify more than 4,000 previously unrecognized genetic and chemical modulators of decidualization. Ontology analysis revealed several groups of decidualization modulators, including many previously unappreciated transcription factors, sensory receptors, growth factors, and kinases. Expression studies of hits revealed that the majority of decidualization modulators are acutely sensitive to ovarian hormone exposure. Gradient treatment of exogenous factors was used to identify EC₅₀ values of small-molecule hits, as well as verify several growth factor hits identified by the siRNA screen. The high-throughput decidualization reporter cell line and the findings described herein will aid in the development of patient-specific treatments for decidualization-based recurrent pregnancy loss, subfertility, and infertility.