Molecular Signaling Regulating Endometrium-Blastocyst Crosstalk

Mechanism of Cnidii Fructus in the Treatment of Infertility Based on Network Pharmacology and Molecular Docking Analysis Technology

Infertility is a condition characterized by a low fertility rate, which significantly affects the physical and mental health of women of reproductive age. Typically, the treatment duration is prolonged, and the therapeutic outcomes are often unsatisfactory. Professor Cheng-yao He, a renowned expert in traditional Chinese medicine, commonly uses the herb Cnidii Fructus (SCZ) for the treatment of infertility. However, the exact mechanism remains unclear, and there is limited research available on this topic. The active ingredients of SCZ were obtained from the traditional chinese medicine system pharmacology (TCMSP) database and screened for pharmacokinetics (PK), involving absorption, distribution, metabolism, and excretion (ADME). Target prediction was performed by SwissTargetPrediction database, and infertility-related disease targets were searched in GeneCards, TTD, DrugBank, and OMIM database. The protein-protein interaction (PPI) network was constructed using the STRING database (Version 11.5) and analyzed by Cytoscape software (Version 3.9.1). Additionally, the target genes were subjected to biological enrichment analysis in the Metascape database, including gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis, and the "Disease-Ingredient-pathway-target" network was constructed using Cytoscape software. With the assistance of AutoDockVina, Ligplot, and PyMOL software, a validation of Molecular docking results and a visualization of the results were performed. This study identified 11 retained active ingredients of SCZ, 447 drug targets, 233 of which were related to infertility, and 5393 disease targets. GO enrichment analysis mainly involved 221 biological processes such as cellular response to chemical stress and gland development. KEGG enrichment analysis mainly involved 68 pathways such as thyroid hormone signaling pathway, estrogen signaling pathway, FOXO signaling pathway, and PI3K/Akt signaling pathway. Molecular docking showed that the core active ingredients of SCZ, including Ammidin, Diosmetin, Xanthoxylin N, and Prangenidin, had strong binding abilities with core targets such as MDM2, MTOR, CCND1, EGFR, and AKT1. This study preliminarily demonstrated that SCZ may act on the PI3K/Akt signaling pathway, exerting its therapeutic effects on infertility by improving energy metabolism disorders and endometrial receptivity, inducing primordial follicle activation, regulating oocyte proliferation, differentiation, and apoptosis, and promoting the release of dominant follicles.

Notch Signaling: An Emerging Paradigm in the Pathogenesis of Reproductive Disorders and Diverse Pathological Conditions

The highly conserved Notch pathway, a pillar of juxtacrine signaling, orchestrates intricate intercellular communication, governing diverse developmental and homeostatic processes through a tightly regulated cascade of proteolytic cleavages. This pathway, culminating in the migration of the Notch intracellular domain (NICD) to the nucleus and the subsequent activation of downstream target genes, exerts a profound influence on a plethora of molecular processes, including cell cycle progression, lineage specification, cell-cell adhesion, and fate determination. Accumulating evidence underscores the pivotal role of Notch dysregulation, encompassing both gain and loss-of-function mutations, in the pathogenesis of numerous human diseases. This review delves deep into the multifaceted roles of Notch signaling in cellular dynamics, encompassing proliferation, differentiation, polarity maintenance, epithelial-mesenchymal transition (EMT), tissue regeneration/remodeling, and its intricate interplay with other signaling pathways. We then focus on the emerging landscape of Notch aberrations in gynecological pathologies predisposing individuals to infertility. By highlighting the exquisite conservation of Notch signaling in Drosophila and its power as a model organism, we pave the way for further dissection of disease mechanisms and potential therapeutic interventions through targeted modulation of this master regulatory pathway.

Effects of Variable Embryo Transfer on the Variable Window of Implantation and Analysis of Pregnancy Outcomes

Background A descriptive analysis of patients who underwent various embryo transfer methods to address the root cause of their infertility at a tertiary infertility care complex in Wardha, India, is presented herein. This analysis aims to evaluate the management of infertility and assess pregnancy outcomes. Methodology We conducted a retrospective cohort study on patients who underwent various embryo transfer methods to address the cause of their infertility, specifically focusing on a variable window of implantation (WOI) at a tertiary infertility clinic over a one-year period. The medical records of 11 patients in both the variable embryo transfer (VET) and control groups were reviewed and analyzed for this article. Results The examination of medical records revealed a significant improvement in the rate of implantation (p-value = 0.04) and clinical pregnancy outcomes (p-value = 0.03) among patients who underwent VET. Comparable statistical outcomes were observed for other variables of pregnancy outcome, including miscarriage rate, multiple pregnancy rate, and biochemical pregnancy rate. Conclusion This retrospective cohort study suggests that the utilization of VET could be a viable option for women experiencing recurrent implantation failure cycles, particularly when an adequate number of embryos are available. This is owing to the challenges in clinically diagnosing a variable WOI. Further studies with a significantly larger sample population are recommended to validate the results and integrate this approach into the standard operating procedures, aiming to enhance the likelihood of pregnancy in these populations.

Caesarean Section Scar and Placental Location at the First Trimester of Pregnancy-A Prospective Longitudinal Study

Background and Objectives: This study aims to report the location of the placenta in the first trimester of pregnancy in groups of women according to the number of previous caesarean deliveries and the visibility of the caesarean scar niche. Materials and Methods: The prospective observational research included adult women aged 18 to 41 years during pregnancy after one or more previous caesarean sections (CSs). Transvaginal (TVS) and transabdominal sonography (TAS) was used to examine the uterine scar and placental location during 11-14 weeks. The CS scar niche ("defect") was bordered in the sagittal plane as a notch at the previous CS scar's site with a depth of 2.0 mm or more. A comparative analysis of the placental location (high or low and anterior or posterior) was performed between groups of women according to the CS number and the CS scar niche. Results: A total of 122 participants were enrolled during the first-trimester screening. The CS scar defect ("niche") was visible in 40.2% of cases. In cases after one previous CS, the placenta was low in the uterine cavity (anterior or posterior) at 77.4%, and after two or more CSs, it was at 67.9%. Comparing the two groups according to the CS scar niche, the placenta was low in 75.5% of cases in the participant group with a CS scar niche and in 75% of cases without a CS scar niche (p = 0.949). Conclusions: The number of previous caesarean deliveries has no effect on the incidence rate of low-lying placentas in the first trimester. Moreover, the presence of the CS scar niche is not associated with anterior low-lying placentas.

APOE-E4 allele as a potential marker for implantation failure: A comparison between fertile women, ART success and RIF patients

OBJECTIVE

Apolipoprotein E (APOE) is the most important precursor for the production of steroid hormones and is also involved in regulating the function of steroid hormones, hence playing a significant role in reproductive processes. So, APOE gene expression may be correlated with the implantation process. This study tries to make a better clarification of the correlation between APOE gene polymorphisms and recurrent implantation failure (RIF), where we compared the frequency of APOE polymorphisms in RIF patients, assisted reproductive treatment (ART) success cases and fertile women.

METHOD

In all, 100 women with successful ART who got pregnant (fetal heart rate positive) in their first or second cycle of in vitro fertilization or intracytoplasmic sperm injection, 100 infertile RIF cases, and 100 normal fertile control cases with at least one live birth were included in present study. Following DNA extraction, genotypes were determined through polymerase chain reaction-restriction fragment length polymorphism method using HhaI restriction enzyme. Finally, statistical analysis was performed by chi-squared (χ2) test in SPSS software (P < 0.05).

RESULTS

The RIF group showed significantly higher frequency for E3/E4 genotype (29%) compared with the other two control groups (fertile = 15%, ART success [ART+] = 13%) (P = 0.007). There was also a significantly higher frequency of the E4 allele in the RIF group (14.5%) compared with both of the control groups (fertile = 7.5%, ART+ = 6.5%) (P = 0.018).

CONCLUSION

APOE4 is correlated with recurrent failure in the process of embryo implantation and, accordingly, it may potentially be considered a possible risk factor to the implantation process. The presence of E4 can be proposed as a predictive indicator in determining the results of assisted reproductive techniques.

Competent blastocyst and receptivity endometrium improved clinical pregnancy in fresh embryo transfer cycles: a retrospective cohort study

BACKGROUND

Embryo quality is usually regarded as a key predictor of successful implantation and clinical pregnancy potential. The identification of embryos that have the capacity to implant and result in a healthy pregnancy is a crucial part of in vitro fertilization (IVF). Usually, morphologically high-quality embryos are chosen for embryo transfer in IVF treatment. The aim of this study was to assess the association between the available blastocyst formation rate and the clinical pregnancy outcome following the first fresh embryo transfer cycle and provide systematic individual treatment to adjust endometrial receptivity for the next transfer cycle.

METHODS

This retrospective, single-center study included 512 fresh embryo transfers conducted between 11/2019 and 08/2021, which consisted of 385 cleavage-stage (Day 3) and 127 blastocyst-stage (Day 5) embryo transfers. The two groups were divided into a clinical pregnancy group and a nonclinical pregnancy group for comparison. The association between the available blastocyst formation rate and the clinical pregnancy rate in the Day 3 and Day 5 transfer groups were considered.

RESULTS

In the Day 3 group, there were 275 clinical pregnancies, and the clinical pregnancy rate was 71.43%. Although the two pronuclei (2PN) oocyte rate and available embryo rate at Day 3 were significantly higher in the clinical pregnancy group than the nonclinical pregnancy group (P < 0.05), the blastocyst formation rate and the available blastocyst formation rate were not significantly different between the clinical pregnancy group and the nonclinical pregnancy group (P > 0.05). In the Day 5 group, there were 81 clinical pregnancies, and the clinical pregnancy rate was 63.78%. No baseline characteristics showed any obvious differences between the clinical pregnancy group and nonclinical pregnancy group (P > 0.05). The blastocyst formation rate in the nonclinical pregnancy group was higher than that in the clinical pregnancy group, but the difference was not statistically significant (81.06% vs. 77.03%, P = 0.083). Interestingly, the available blastocyst formation rate and the Day 5 available blastocyst formation rate were significantly higher in the nonclinical pregnancy group than the clinical pregnancy group (66.19% vs. 60.79%, P = 0.014; 54.58% vs. 46.98%, P = 0.007).

CONCLUSIONS

In fresh cycles, the available blastocyst formation rate was not associated with the clinical pregnancy outcome for Day 3 embryo transfers, and the available blastocyst formation rate was not positively correlated with the clinical pregnancy outcome for Day 5 embryo transfers.

In vivo effect of vaginal seminal plasma application on the human endometrial transcriptome: a randomized controlled trial

Studies in humans and animals suggest that seminal plasma, the acellular seminal fluid component, stimulates the endometrium to promote immune tolerance and facilitate implantation. We designed a randomized, double-blinded, placebo-controlled trial to investigate changes in the endometrial transcriptomic profile after vaginal application of seminal plasma. The study participants were randomized into two groups. Five women received a vaginal application of seminal plasma, and four received a placebo application with saline solution. The application was performed 2 days after HCG-triggered ovulation in an unstimulated cycle. After 5-8 days, an endometrial biopsy was collected to analyze differences in the endometrial transcriptomic profile using microarray analyses. A differential gene expression analysis and a gene set analysis were performed. The gene set enrichment analysis showed a positive enrichment of pathways associated with the immune response, cell viability, proliferation, and cellular movement. Moreover, pathways involved in implantation, embryo development, oocyte maturation, and angiogenesis were positively enriched. The differential gene expression analysis, after adjusting for multiple testing, showed no significantly differentially expressed genes between the two groups. A comparative analysis was also performed with similar studies conducted in other animals or in vitro using human endometrial cells. The comparative analysis showed that the effect of seminal plasma effect on the endometrium is similar in pigs, mice, and in vitro human endometrial cells. The present study provides evidence that seminal plasma might impact the endometrium during the implantation window, with potential to affect endometrial receptivity and embryo development.

Celecoxib attenuates interleukin 33-induced expression of vascular cell adhesion molecule-1 in human ovarian endometriotic stromal cells

OBJECTIVE

Endometriosis is an estrogen-dependent chronic inflammatory disease in women of reproductive age. A review of the literature revealed that cytokines and inflammatory factors are associated with endometriosis-associated infertility. Interleukin 33 (IL-33) is a strong inducer of other pro-inflammatory cytokines. Vascular cell adhesion molecule-1 (VCAM-1) plays a central role in recruiting inflammatory cells, whose expression facilitates leukocyte adhesion and is rapidly induced by pro-inflammatory cytokines. Many studies have indicated that VCAM-1 expression is high in endometriosis; however, whether the expression of VCAM-1 is related to IL-33 is unclear.

MATERIALS AND METHODS

Human ovarian endometriotic stromal cells (hOVEN-SCs) were treated with IL-33 to enable investigation of cell characterization, gene and protein expression, and signal pathways. Proliferation potential was measured using an MTT assay. Gene expression was analyzed using reverse transcription-polymerase chain reaction. Protein expression assay was performed using western blot analysis.

RESULTS

This study investigated the effects of IL-33 on VCAM-1 and COX-2 expression in hOVEN-SCs. First, the results revealed that the IL-33/ST2/mitogen-activated protein kinase (MAPK) signaling pathway could increase the expression of VCAM-1 and COX-2 in hOVEN-SCs. Second, we discovered that COX-2 expression was essential for IL-33-induced VCAM-1 expression because the effects could be negated through NS398, a selective COX-2 inhibitor. Finally, treatment of IL-33-treated hOVEN-SCs with celecoxib significantly and dose-responsively decreased VCAM-1 expression.

CONCLUSION

Taken together, these results indicate that IL-33 can upregulate VCAM-1 expression in hOVEN-SCs through the IL-33/ST2/MAPK/COX-2 signaling pathway and thereby contribute to endometriosis.

When the Embryo Meets the Endometrium: Identifying the Features Required for Successful Embryo Implantation

Evaluation of the optimal number of embryos, their quality, and the precise timing for transfer are critical determinants in reproductive success, although still remaining one of the main challenges in assisted reproduction technologies (ART). Indeed, the success of in vitro fertilization (IVF) treatments relies on a multitude of events and factors involving both the endometrium and the embryo. Despite concerted efforts on both fronts, the overall success rates of IVF techniques continue to range between 25% and 30%. The role of the endometrium in implantation has been recently recognized, leading to the hypothesis that both the "soil" and the "seed" play a central role in a successful pregnancy. In this respect, identification of the molecular signature of endometrial receptivity together with the selection of the best embryo for transfer become crucial in ART. Currently, efforts have been made to develop accurate, predictive, and personalized tests to identify the window of implantation and the best quality embryo. However, the value of these tests is still debated, as conflicting results are reported in the literature. The purpose of this review is to summarize and critically report the available criteria to optimize the success of embryo transfer and to better understand current limitations and potential areas for improvement.

Advances in the use of organoids in endometrial diseases

The endometrium undergoes cyclical changes in response to hormones and there is a certain degree of heterogeneity among individuals. In vivo identification of the physiologic changes of the endometrium and the pathologic process of related diseases is challenging. There have been recent advances in the use of organoids that mimic the characteristics of the corresponding organs and the morphologic, functional, and personalized characteristics involved in different stages of diseases. In this paper, we discuss the process of creating endometrial organoids, cell sources, types of extracellular matrices, and their application in the study of physiologic endometrial states and various diseases.

Epigenetic role of LINE-1 methylation and key genes in pregnancy maintenance

Spontaneous abortion is a pregnancy complication characterized by complex and multifactorial etiology. About 5% of childbearing women are globally affected by early pregnancy loss (EPL) and most of them experience recurrence (RPL). Epigenetic mechanisms and controlled inflammation are crucial for pregnancy maintenance and genetic predispositions may increase the risk affecting the maternal-fetal crosstalk. Combined analyses of global methylation, inflammation and inherited predispositions may contribute to define pregnancy loss etiopathogenesis. LINE-1 epigenetic regulation plays crucial roles during embryo implantation, and its hypomethylation has been associated with senescence and several complex diseases. By analysing a group of 230 women who have gone through pregnancy interruption and comparing those experiencing spontaneous EPL (n = 123; RPL, 54.5%) with a group of normal pregnant who underwent to voluntary interruption (VPI, n = 107), the single statistical analysis revealed significant lower (P < 0.00001) LINE-1 methylation and higher (P < 0.0001) mean cytokine levels (CKs: IL6, IL10, IL17A, IL23) in EPL. Genotyping of the following SNPs accounted for different EPL/RPL risk odds ratio: F13A1 rs5985 (OR = 0.24; 0.06-0.90); F13B rs6003 (OR = 0.23; 0.047-1.1); FGA rs6050 (OR = 0.58; 0.33-1.0); CRP rs2808635/rs876538 (OR = 0.15; 0.014-0.81); ABO rs657152 (OR = 0.48; 0.22-1.08); TP53 rs1042522 (OR = 0.54; 0.32-0.92); MTHFR rs1801133/rs1801131 (OR = 2.03; 1.2-3.47) and FGB rs1800790 (OR = 1.97; 1.01-3.87), although Bonferroni correction did not reach significant outputs. Principal Component Analysis (PCA) and logistic regression disclosed further SNPs positive/negative associations (e.g. APOE rs7412/rs429358; FGB rs1800790; CFH rs1061170) differently arranged and sorted in four significant PCs: PC1 (F13A, methylation, CKs); PC3 (CRP, MTHFR, age, methylation); PC4 (F13B, FGA, FGB, APOE, TP53, age, methylation); PC6 (F13A, CFH, ABO, MTHFR, TP53, age), yielding further statistical power to the association models. In detail, positive EPL risk association was with PC1 (OR = 1.81; 1.33-2.45; P < 0.0001) and negative associations with PC3 (OR = 0.489; 0.37-0.66; P < 0.0001); PC4 (OR = 0.72; 0.55-0.94; P = 0.018) and PC6 (OR = 0.61; 0.46-0.81; P = 0.001). Moreover, significant inverse associations were detected between methylation and CKs levels in the whole group (rIL10 = - 0.22; rIL17A = - 0.25; rIL23 = - 0.19; rIL6 = - 0.22), and methylation with age in the whole group, EPL and RPL subgroups (r2TOT = 0.147; r2EPL = 0.136; r2 RPL = 0.248), while VPI controls lost significance (r2VPI = 0.011). This study provides a valuable multilayer approach for investigating epigenetic abnormalities in pregnancy loss suggesting genetic-driven dysregulations and anomalous epigenetic mechanisms potentially mediated by LINE-1 hypomethylation. Women with unexplained EPL might benefit of such investigations, providing new insights for predicting the pregnancy outcome and for treating at risk women with novel targeted epidrugs.

Unveiling the Role of Endometrial CD-138: A Comprehensive Review on Its Significance in Infertility and Early Pregnancy

This review comprehensively examines the role of endometrial CD-138 (syndecan-1) in the context of infertility and early pregnancy. The endometrium, a dynamic tissue responsive to hormonal cues, plays a central role in fertility, and understanding the molecular intricacies governing its function is crucial. CD-138, a cell surface proteoglycan, emerges as a critical player expressed by various endometrial cell types. Our exploration encompasses a brief overview of the endometrium, introducing CD-138 as a significant molecular entity. The rationale for the review underscores the importance of elucidating endometrial factors in fertility and addresses existing knowledge gaps related to CD-138. Throughout the review, we unravel the multifaceted nature of CD-138 and its involvement in infertility, highlighting its potential as a diagnostic marker. Furthermore, insights into CD-138's role during early pregnancy, including trophoblast-endothelial interactions, are discussed. In conclusion, the findings underscore the clinical implications of CD-138, suggesting its utility in diagnostics and offering prospects for targeted therapeutic interventions. The identified knowledge gaps propel future research directions, promising to deepen our understanding of this enigmatic molecule and its transformative potential in reproductive medicine.

A Case Series Based on the Mixed Double-Embryo Transfer (MDET) Outcome in Patients With Recurrent Implantation Failure

Successful implantation of embryos depends on the synchronous cross-talks between the endometrial wall and the competent blastocyst within the window of implantation (WOI). Hence, the WOI has a major significance in assisted reproductive technology (ART). However, in some cases, women do not have fixed WOI in ART cycles in order to enhance the rate of successful clinical pregnancy. However, there have been stances where women do not have a fixed WOI, and it shifts in subsequent menstrual periods. This contributes to the chances of recurrent implantation failure (RIF). Another factor that contributes to RIF is erratic endometrial receptivity, which hinders the chances of successful implantation of the conceptus in the endometrium. This case series consists of four case studies where the patients were believed to be suffering from RIF due to variable WOI or erratic endometrial receptivity and the routine protocol followed nowadays failed to make them conceive. In order to resolve the condition, we proposed a novel strategy in an attempt to improve pregnancy rates in these cases. An innovative method of embryo transfer known as mixed double-embryo transfer (MDET), which involved the transfer of one day 3 embryo and one day 5 blastocyst on day 6 of progesterone, led to possible pregnancy outcomes. A viable pregnancy was validated based on the human chorionic gonadotropin (β-hCG) test report, and two of the cases delivered healthy babies. Thus, this case series provides a unique approach to addressing the issues of RIF. However, larger studies are required to validate the possible use of this technique.

CsA promotes trophoblast invasion accompanied by changes in leukaemic inhibitory factor and fibroblast growth factor in peri-implantation blastocysts

During the early stages of human pregnancy, successful implantation of embryonic trophoblast cells into the endometrium depends on good communication between trophoblast cells and the endometrium. Abnormal trophoblast cell function can cause embryo implantation failure. In this study, we added cyclosporine A (CsA) to the culture medium to observe the effect of CsA on embryonic trophoblast cells and the related mechanism. We observed that CsA promoted the migration and invasion of embryonic trophoblast cells. CsA promoted the expression of leukaemic inhibitory factor (LIF) and fibroblast growth factor (FGF). In addition, CsA promoted the secretion and volume increase in vesicles in the CsA-treated group compared with the control group. Therefore, CsA may promote the adhesion and invasion of trophoblast cells through LIF and FGF and promote the vesicle dynamic process, which is conducive to embryo implantation.

Endometrial BMP2 Deficiency Impairs ITGB3-Mediated Trophoblast Invasion in Women With Repeated Implantation Failure

BACKGROUND

Repeated implantation failure (RIF) leads to a waste of high-quality embryos and remains a challenge in assisted reproductive technology. During early human placentation, the invasion of trophoblast cells into the decidua is an essential step for the establishment of maternal-fetal interactions and subsequent successful pregnancy. Bone morphogenetic protein 2 (BMP2) has been reported to regulate endometrial receptivity and promote trophoblast invasion. However, whether there is dysregulation of endometrial BMP2 expression in patients with RIF remains unknown. Additionally, the molecular mechanisms underlying the effects of BMP2 on human trophoblast invasion and early placentation remain to be further elucidated.

METHODS

Midluteal phase endometrial samples were biopsied from patients with RIF and from routine control in vitro fertilization followed by quantitative polymerase chain reaction and immunoblotting analyses. Human trophoblast organoids, primary human trophoblast cells, and an immortalized trophoblast cell line (HTR8/SVneo) were used as study models.

RESULTS

We found that BMP2 was aberrantly low in midluteal phase endometrial tissues from patients with RIF. Recombinant human BMP2 treatment upregulated integrin β3 (ITGB3) in a SMAD2/3-SMAD4 signaling-dependent manner in both HTR8/SVneo cells and primary trophoblast cells. siRNA-mediated integrin β3 downregulation reduced both basal and BMP2-upregulated trophoblast invasion and vascular mimicry in HTR8/SVneo cells. Importantly, shRNA-mediated ITGB3 knockdown significantly decreased the formation ability of human trophoblast organoids.

CONCLUSION

Our results demonstrate endometrial BMP2 deficiency in patients with RIF. ITGB3 mediates both basal and BMP2-promoted human trophoblast invasion and is essential for early placentation. These findings broaden our knowledge regarding the regulation of early placentation and provide candidate diagnostic and therapeutic targets for RIF clinical management.

IGF2BP2 regulates the proliferation and migration of endometrial stromal cells through the PI3K/AKT/mTOR signaling pathway in Hu sheep

Insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2), a significant member of the conserved RNA-binding protein family, plays various roles in numerous physiological and pathological processes. However, the specific function of IGF2BP2 in regulating endometrial function in sheep remains largely unknown. In this study, we observed a significant upregulation in IGF2BP2 mRNA abundance in the endometrium during the luteal phase compared to the follicular phase in Hu sheep. The knockdown of IGF2BP2 resulted in accelerated cell proliferation and migration of Hu sheep endometrial stromal cells (ESCs). Moreover, RNA sequencing analysis revealed that genes with significantly altered expression in IGF2BP2 knockdown cells were predominantly enriched in endometrial receptivity-related signaling pathways, such as cytokine-cytokine receptor interaction, NOD-like receptor, PI3K-AKT, and JAK-STAT signaling pathway. Additionally, the knockdown of IGF2BP2 significantly increased the expression of matrix metalloprotein 9 (MMP9), vascular endothelial growth factor, and prolactin (PRL) in ESCs. The knockdown of IGF2BP2 was also observed to stimulate the PI3K/AKT/mTOR pathway by upregulating integrin β4 (ITGB4) expression. Notably, the downregulation of ITGB4 attenuates IGF2BP2 knockdown-induced facilitation of proliferation and migration of Hu sheep ESCs by inhibiting the PI3K/AKT/mTOR pathway. Collectively, these findings highlight the important role of IGF2BP2 in regulating endometrial function, particularly through the modulation of ESC proliferation and migration via the PI3K/AKT/mTOR pathway.

Molecular Determinants of Uterine Receptivity: Comparison of Successful Implantation, Recurrent Miscarriage, and Recurrent Implantation Failure

Embryo implantation is one of the most remarkable phenomena in human reproduction and is not yet fully understood. Proper endometrial function as well as a dynamic interaction between the endometrium itself and the blastocyst-the so-called embryo-maternal dialog-are necessary for successful implantation. Several physiological and molecular processes are involved in the success of implantation. This review describes estrogen, progesterone and their receptors, as well as the role of the cytokines interleukin (IL)-6, IL-8, leukemia inhibitory factor (LIF), IL-11, IL-1, and the glycoprotein glycodelin in successful implantation, in cases of recurrent implantation failure (RIF) and in cases of recurrent pregnancy loss (RPL). Are there differences at the molecular level underlying RIF or RPL? Since implantation has already taken place in the case of RPL, it is conceivable that different molecular biological baseline situations underlie the respective problems.

Insufficient GDF15 expression predisposes women to unexplained recurrent pregnancy loss by impairing extravillous trophoblast invasion

Insufficient extravillous trophoblast (EVT) invasion during early placentation has been shown to contribute to recurrent pregnancy loss (RPL). However, the regulatory factors involved and their involvement in RPL pathogenesis remain unknown. Here, we found aberrantly decreased growth differentiation factor 15 (GDF15) levels in both first-trimester villous and serum samples of unexplained recurrent pregnancy loss (URPL) patients as compared with normal pregnancies. Moreover, GDF15 knockdown significantly reduced the invasiveness of both HTR-8/SVneo cells and primary human EVT cells and suppressed the Jagged-1 (JAG1)/NOTCH3/HES1 pathway activity, and JAG1 overexpression rescued the invasion phenotype of the GDF15 knockdown cells. Induction of a lipopolysaccharide-induced abortion model in mice resulted in significantly reduced GDF15 level in the placenta and serum, as well as increased rates of embryonic resorption, and these effects were reversed by administration of recombinant GDF15. Our study thus demonstrates that insufficient GDF15 level at the first-trimester maternal-foetal interface contribute to the pathogenesis of URPL by impairing EVT invasion and suppressing JAG1/NOTCH3/HES1 pathway activity, and suggests that supplementation with GDF15 could benefit early pregnancy maintenance and reduce the risk of early pregnancy.

Yueliang Yin Ameliorates Endometrial Receptivity in Mice with Embryo Implantation Failure by Reducing Pyroptosis and Activating BDNF/TrkB Pathway

SCOPE

Endometrial receptivity plays a vital role in embryonic implantation. Yueliang Yin is a marketed solid drink in China, also known as Bushen Cuyun Recipe (BCR), that is, assumed to have a therapeutic effect on infertility by improving endometrial receptivity. This study investigates the effects and mechanisms of BCR in protecting the endometrium.

METHODS AND RESULTS

Mice with mifepristone-induced embryo implantation failure that exhibited a decreased implantation sites number, thinner endometrium, reduced endometrial glands number, and poor pinopode expression levels are treated with BCR, and these mentioned conditions significantly improves afterward. Molecular docking shows that the main active components kaempferol, quercetin, and hesperetin of BCR stably bound to gasdermin D (GSDMD). Experimental results demonstrate that levels of GSDMD, cleaved caspase-1 and leucine-rich repeat, and pyrin domain-containing 3 and IL-1β levels in model mice are significantly decreased and expressions of brain-derived neurotrophic factor (BDNF) and tyrosine protein kinase B (TrkB) expression levels are significantly elevated after BCR treatments, and that the DNA damage is significantly reversed in BCR-treated mice.

CONCLUSIONS

BCR is potent and effective in ameliorating endometrial receptivity. The potential mechanisms of BCR on endometrial receptivity may mediate by activating BDNF/TrkB pathway activation and protecting endometrial cells' protection against pyroptosis.

Role of Endometrial Extracellular Vesicles in Mediating Cell-to-Cell Communication in the Uterus: A Review

There are several critical events that occur in the uterus during early pregnancy which are necessary for the establishment and maintenance of pregnancy. These events include blastocyst implantation, uterine decidualization, uterine neoangiogenesis, differentiation of trophoblast stem cells into different trophoblast cell lineages, and formation of a placenta. These processes involve several different cell types within the pregnant uterus. Communication between these cell types must be intricately coordinated for successful embryo implantation and the formation of a functional maternal-fetal interface in the placenta. Understanding how this intricate coordination transpires has been a focus of researchers in the field for many years. It has long been understood that maternal endometrial tissue plays a key role in intercellular signaling during early pregnancy, sending signals to nearby tissues in a paracrine manner. Recently, insights have been obtained into the mechanisms by which these signaling events occur. Notably, the endometrium has been shown to secrete extracellular vesicles (EVs) that contain crucial cargo (proteins, lipids, RNA, miRNA) that are taken up by recipient cells to initiate a response leading to the occurrence of critical events during implantation and placentation. In this review, we aim to summarize the role that endometrium-derived EVs play in mediating cell-to-cell communications within the pregnant uterus to orchestrate the events that must occur to establish and maintain pregnancy. We will also discuss how aberrant endometrial EV signaling may lead to pathophysiological conditions, such as endometriosis and infertility.

In-Vitro Decidualization With Different Progesterone Concentration: Development of a Hormone-Responsive 3D Endometrial Tissue Using Rat Endometrial Tissues

Infertility in women is associated with various uterine and ovarian disorders. Treatment strategies for infertility can range from medications to embryo implantation through assisted reproductive technology (ART). ART has enabled considerable progress; however, there is currently no treatment to replace the endometrium itself. Decidualization requires a complex interaction between endometrial tissue and estrogen and progesterone. We aimed to create a three-dimensional endometrial-like tissue model using in-vitro cell sheet engineering with rat endometrium, and culture cells at different progesterone concentrations to mimic local concentrations. Histological and morphological changes revealed that development of the endometrial-like tissue was not proportional to progesterone concentrations in terms of thickness, number of endometrial glands, or area fraction of intimal glands. These results suggest that decidualization may not be commensurate with the local endometrial progesterone concentration. Notably, the number of endometrial glands increased in the high concentration group and compaction occurred, indicating that the endometrial conditions in the high concentration group may be most conducive to increase pregnancy rates. These findings suggest that there may be an "optimal progesterone concentration" for decidualization, application of which may lead to new strategies for improving pregnancy rates in women with infertility.

Thyroid dysfunction and female infertility. A comprehensive review

INTRODUCTION

Female infertility is defined as the inability to achieve pregnancy following one year of consistent, unprotected sexual intercourse. Among the various endocrine factors contributing to this complex issue, thyroid dysfunction assumes a pivotal and noteworthy role.

METHODS

A narrative review, encompassing 134 articles up to 2023, was conducted utilizing the PubMed/Medline, EMBASE, and Scielo databases. The primary focus of this review was to investigate the effects of thyroid dysfunction on female infertility.

RESULTS

Thyroid disorders exert a significant influence on folliculogenesis, fertilization, and implantation processes. Thyroid autoimmunity, although associated with diminished ovarian reserve, does not typically necessitate levothyroxine therapy. On the other hand, both subclinical and overt hypothyroidism often require levothyroxine treatment to enhance fertility and optimize obstetric outcomes. Hyperthyroidism warrants prompt intervention due to its heightened risk of miscarriage. Furthermore, thyroid dysfunction exerts notable effects on assisted reproductive technologies, underscoring the importance of achieving euthyroidism prior to ovarian stimulation.

CONCLUSION

Women presenting with thyroid dysfunction must undergo meticulous and individualized assessments since fertility outcomes, whether achieved through natural conception or assisted reproductive technologies, can be significantly influenced by thyroid-related factors.

An interplay of Progesterone, Leukemia Inhibitor Factor and Interleukin-6 in the window of implantation; Impact on fertility

BACKGROUND

The process of implantation is crucial for the initiation of conception and hence fertility. In addition to a number of factors, it is regulated by a cross talk of gonadotrophins [Luteinizing Hormone (LH), Follicle Stimulatory Hormone (FSH)], ovarian steroids [Estrogen (Et), Progesterone (Pt)] and cytokines [Leukemia inhibitory factor (LIF) and Interleukin 6 (IL6)]. These biomarkers are chief players of implantation.

OBJECTIVE

We aimed to explore the role of gonadotrophins (LH, FSH, LH/FSH ratio), ovarian steroids (Et, Pt) and cytokines (LIF, IL6) in the implantation process. This aim was achieved by comparing these hormones and cytokines in the fertile and infertile groups [Polycystic ovaries (PCOs), endometriosis, unexplained infertility (Uex-IF)] and finding their association in all study groups.

METHODS

A case control study conducted from October 2020-March 2023. A total of 135 infertile women (with PCOs, Uex-IF, and endometriosis) and 177 fertile women (matched for age and BMI) were selected. Levels of 'Et', 'Pt', 'LIF' and, 'IL6' were estimated using Enzyme Linked Immunosorbent Assay (ELISA). LH and FSH values were obtained from hospital desk records. The Independent Student'st-test was used to compare fertile and infertile groups. One-way ANOVA test was used to compare more than two groups, and Pearson's chi-square (χ2) test was employed to compare percentages of variables. Pearson correlation analysis was performed to assess the associations and correlations. A p value < 0.05 was considered statistically significant.

RESULTS

Significantly higher levels of LIF and IL6 were observed in fertile women compared to infertile women. Pt levels were significantly greater in the fertile group than in the infertile group. The FSH/LH ratio was significantly higher in the fertile group. Among infertile women, PCOs (71%) and Uex-IF (91%) exhibited lower Pt levels than the fertile controls (p < 0.01), but these levels remained within the reference range (RR). Among the fertile group (81%), levels of LIF within the RR were significantly higher compared to those with Uex-IF (49%) and females with endometriosis (37%). Moreover, the highest number of participants (57%) with Uex-IF exhibited IL6 levels significantly below the RR in comparison to the fertile group and infertile groups (PCOS and endometriosis). However, lower levels of IL6 were observed in women with Uex-IF. In the control group, LIF exhibited a significant positive correlation with IL6 (r = 0.370), Pt (r = 0.496), Et (r = 0.403), and LH (r = 0.428). Among women with PCOs, LIF showed a significant positive correlation with IL6 (r = 0.443), Pt (r = 0.607), and LH (r = 0.472). In cases of Uex-IF, LIF demonstrated a significant positive correlation with IL6 (r = 0.727). Females with endometriosis displayed a significant positive correlation between LIF and IL6 (r = 0.535) as well as Pt (r = 0.605). In fertile women, a positive correlation was observed between LH and IL6 (r = 0.197, p = 0.009), LIF (r = 0.428, p = 0.000), Pt (r = 0.238, p = 0.001), and Et (r = 0.356, p = 0.000). Furthermore, a positive correlation was found between LH and LIF (r = 0.472, p = 0.000) in women with PCOs.

CONCLUSION

Elevated levels of Pt were found to increase the production of LIF in fertile females. However, infertile females with PCOs and Uex-IF exhibited deficient levels of Pt, supporting its role as a biomarker for successful implantation in infertile women. These females showed decreased levels of gonadotropins as well as reduced LH/FSH ratio and diminished secretion of receptivity marker LIF, in addition to reduced Pt secretion. This suggests that reduced gonadotropin levels contribute to a lower LH/FSH ratio, resulting in decreased Pt secretion and ultimately leading to low levels of LIF, thereby causing impaired implantation in women with PCOs and Uex-IF. The exploration of low levels of LIF in patients with endometriosis requires further investigation. The significantly low levels of IL6 in the Uex-IF group elucidate the role of this cytokine in association with decreased Pt and LIF synthesis within this group.

Sequential embryo transfer versus double cleavage-stage embryo or double blastocyst transfer in patients with recurrent implantation failure with frozen-thawed embryo transfer cycles: a cohort study

Background

Recurrent implantation failure (RIF) is more common among patients receiving assisted reproductive treatment. Many efforts have been made to increase the incidence of clinical pregnancy among patients with RIF. The effect of the sequential transfer procedure, a two-step interval transfer of a cleavage-stage embryo followed by a blastocyst in one transfer cycle, on the clinical outcomes of RIF patients remains controversial.

Methods

In total, 1774 frozen-thawed embryo transfer (FET) cycles in RIF patients were included. Of these cycles, 302 were sequential embryo transfer (ET) cycles, 979 were double day 3 cleavage-stage ET cycles, and 493 were double blastocyst ET cycles. The primary outcomes were the rates of implantation, clinical pregnancy and multiple pregnancy, and the secondary outcomes were the rates of hCG positive, early miscarriage and ectopic pregnancy.

Results

The implantation, hCG positive, and clinical pregnancy rates in the sequential ET group (32.1%, 58.9%, 50.7%) were significantly higher than those in the day 3 cleavage-stage ET group (24.9%, 46.5%, 40.4%) and were similar to those in the blastocyst transfer group (30.1%, 56.4%, 47.1%). The early miscarriage rate in the blastocyst transfer group was significantly higher than that in the cleavage-stage ET group (17.2% vs. 8.1%, P <0.05), while the ectopic pregnancy rate in the blastocyst transfer group was significantly lower than that in the cleavage-stage ET group (0.4% vs. 3.0%, P <0.05). The multiple pregnancy rate in the sequential ET group was significantly lower than that in the cleavage-stage ET group (17.0% vs. 25.5%, P <0.05) and the blastocyst transfer group (17.0% vs. 27.6%, P <0.05). When cycles of blastocyst culture failure were excluded, the clinical pregnancy rate was significantly higher (55.7% vs. 47.1%, P <0.05), and the early miscarriage rate and multiple pregnancy rate were significantly lower (8.5% vs. 17.2%, 17.7% vs. 27.6%; P <0.05, respectively) in the sequential ET group than in the double blastocyst ET group.

Conclusions

Sequential embryo transfer in FET cycles could improve the clinical outcomes of patients with RIF.

Closer to the Reality-Proteome Changes Evoked by Endometrial Scratching in Fertile Females

Endometrial scratching (ES) has been widely used in assisted reproductive technology to possibly improve pregnancy rates, but its exact mechanism is still not understood or investigated, and its benefits are controversially discussed. Hypothetically, ES may trigger a local immune response, leading to an improved endometrial receptivity. So far, it has been shown that ES affects the gene expression of cytokines, growth factors, and adhesive proteins, potentially modulating inflammatory pathways and adhesion molecule expression. Our pilot study applying proteomic analysis reveals that ES probably has an impact on the proteins involved in immune response pathways and cytoskeleton formation, which could potentially increase endometrial receptivity. Specifically, proteins that are involved in the immune response and cytoskeleton regulation showed a trend toward higher abundance after the first ES. On the other hand, proteins with a decreasing abundance after the first ES play roles in the regulation of the actin cytoskeleton and cellular processes such as intracellular transport, apoptosis, and autophagy. These trends in protein changes suggest that ES may affect endometrial tissue stiffness and extracellular matrix remodeling, potentially enhancing the embryos' implantation. To our knowledge, this pilot study provides, for the first time, data investigating potential changes in the endometrium due to the scratching procedure that might explain its possible benefit for patients in infertility treatment. Furthermore, the proteome of a group of patients suffering from repeated implantation failure was compared to that of the fertile group in order to transfer the basic science to clinical routine and application.

Interleukin-6 as A Useful Predictor of Endometriosis-Associated Infertility: A Systematic Review

Endometriosis is a chronic inflammatory disease defined by the presence of endometrial-like tissue outside the uterine cavity. Several authors have reported on the association between changes in inflammatory marker levels and the maintenance or progression of endometriosis and associated infertility. Interleukin-6 (IL-6) is the most studied cytokine in endometriosis and has important functions in reproductive physiology. The aim of this study is to review systematically available evidence about altered IL-6 concentrations in endometriosis-related infertility. This is a systematic review including all studies until December 2022 in which IL-6 in serum, peritoneal fluid, follicular fluid, or endometrial biopsy specimens was measured and that correlated their findings with endometriosis- associated infertility. Fifteen studies were included in the systematic review. There seems to be a correlation between elevated serum and peritoneal fluid IL-6 concentrations and the occurrence of endometriosis-associated infertility. IL-6 may be a potential diagnostic or biomarker tool for the prediction of endometriosis-related infertility. However, the numerous biases affecting the available studies, and challenges in endometriosis research reproducibility must be considered. Future investigations should pay attention to factors that may affect the results, such as the choice of suitable control groups, and carefully consider other pathological conditions affecting the patients, endometriosis stage, and type of lesion.

Co-Culture of Mouse Blastocysts on A Human Recellularized Endometrial Scaffold: An In Vitro Model for Future Implantation Studies

OBJECTIVE

This study evaluates the interaction of mouse blastocysts as a surrogate embryo on a recellularized endometrial scaffold by seeding human endometrial mesenchymal cells (hEMCs).

MATERIALS AND METHODS

In this experimental study, prepared decellularized human endometrial tissues were characterized by morphological staining, DNA content analysis, and scanning electron microscopic (SEM) analysis. The scaffolds were subsequently recellularized by hEMCs. After seven days of cultivation, the mouse blastocysts were co-cultured on the recellularized scaffolds for 48 hours. Embryo attachment and implantation within these scaffolds were evaluated at the morphological, ultrastructural, molecular, and hormonal levels.

RESULTS

There was no morphological evidence of cells and nuclei in the decellularized scaffold. DNA content significantly decreased by 89.92% compared to the control group (P<0.05). Both decellularized and native tissues had similar patterns of collagen bundles and elastin fibers, and glycosaminoglycan (GAGs) distribution in the stroma. After recellularization, the hEMCs attached to the scaffold surface and penetrated different parts of these scaffolds. In the co-cultured group, the embryo attached to the surface of the scaffold after 24 hours and penetrated the recellularized endometrial tissue after 48 hours. We observed multi-layered organoid-like structures formed by hEMC proliferation. The relative expressions of epithelial-related genes, ZO-1 and COL4A1, and SSP1, MMP2, and PRL, as decidualizationrelated genes, were significantly higher in the recellularized group on day 9 in the presence of the embryo compared to the other groups (P<0.05). Beta human chorionic gonadotropin (β-hCG) and prolactin were statistically increased in the recellularized group on day 9 group (P<0.05).

CONCLUSION

hEMCs and mouse embryo co-cultured on a decellularized endometrial scaffold provides an alternative model to study embryo implantation and the earlier stage of embryo development.

Expressions of Notch signalling pathway members during early pregnancy in mice

Although pregnancy is initiated and maintained through highly complex mechanisms, it is essential to understand the events that occur before and during early pregnancy to understand a healthy implantation process. The Notch signal, thought to be involved in this process, is frequently the subject of research with its different aspects. To better understand the role of Notch signaling in the peri-implantation period of the mouse uterus, we investigated the state of expression and localization of Notch 3, Notch 4, Rbp-J, Hes1, Hes7, Hey2, HeyL, and Fbw7 in the uterus and implantation sites in early pregnancy. Balb/C mice were divided into groups D1, D4, D5, D6, and D8. For D5 and D6 groups, implantation sites were identified by intravenous injection of Chicago blue. IHC, WB, and QRT-PCR methods were used. Notch 3 was very strong positive on the 4th day of pregnancy. Notch 4 was highly expressed on days 4, 5, 6, and 8 of pregnancy when P4 levels were high. Hes 1 level was at the lowest on the 4th day of pregnancy. Hes 7 protein expression gradually increased from D1 to D8 in the uteri and implantation sites. Hey 2 expression was at the highest level on the 1st and 4th days. Hey L expression was on the apical of the glands. Fbxw7 that expression was high on the 1st and 4th days of pregnancy. Notch signaling may play an essential role in regulating endometrial receptivity. In addition, our Hes7 results are new to the literature.

A novel machine learning model for predicting clinical pregnancy after laparoscopic tubal anastomosis

BACKGROUND

Laparoscopic tubal anastomosis (LTA) is a treatment for women who require reproduction after ligation, and there are no reliable prediction models or clinically useful tools for predicting clinical pregnancy in women who receive this procedure. The prediction model we developed aims to predict the individual probability of clinical pregnancy in women after receiving LTA.

METHODS

Retrospective analysis of clinical data of patients undergoing LAT in the Second Hospital of Lanzhou University from July 2017 to December 2021. Least absolute shrinkage and selection operator (LASSO) regression was used for data dimension reduction and feature selection. We incorporated the patients' basic characteristics, preoperative laboratory tests and laparoscopic tubal anastomosis procedure signature and obtained a nomogram. The model performance was evaluated in terms of its calibration, discrimination, and clinical applicability. The prediction model was further internally validated using 200 bootstrap resamplings.

RESULTS

A total of 95 patients were selected to build the predictive model for clinical pregnancy after LTA. The LASSO method identified age, intrauterine polyps, pelvic adhesion and thyroid stimulating hormone(TSH) as independent predictors of the clinical pregnancy rate. The prediction nomogram included the abovementioned four predictive parameters. The model showed good discrimination with an area under the curve (AUC) value of 0.752. The Hosmer‒Lemeshow test of calibration showed that χ2 was 4.955 and the p value was 0.838, which indicates a satisfactory goodness-of-fit. Decision curve analysis demonstrated that the nomogram was clinically useful. Internal validation shows that the predictive model performs well.

CONCLUSION

This study presents a nomogram incorporating age, intrauterine polyps, pelvic adhesion and TSH based on the LASSO regression model, which can be conveniently used to facilitate the individualized prediction of clinical pregnancy in women after LTA.

Embryo-derive TNF promotes decidualization via fibroblast activation

Decidualization is a process in which endometrial stromal fibroblasts differentiate into specialized secretory decidual cells and essential for the successful establishment of pregnancy. The underlying mechanism during decidualization still remains poorly defined. Because decidualization and fibroblast activation share similar characteristics, this study was to examine whether fibroblast activation is involved in decidualization. In our study, fibroblast activation-related markers are obviously detected in pregnant decidua and under in vitro decidualization. ACTIVIN A secreted under fibroblast activation promotes in vitro decidualization. We showed that arachidonic acid released from uterine luminal epithelium can induce fibroblast activation and decidualization through PGI₂ and its nuclear receptor PPARδ. Based on the significant difference of fibroblast activation-related markers between pregnant and pseudopregnant mice, we found that embryo-derived TNF promotes CPLA_2α phosphorylation and arachidonic acid release from luminal epithelium. Fibroblast activation is also detected under human in vitro decidualization. Similar arachidonic acid-PGI₂-PPARδ-ACTIVIN A pathway is conserved in human endometrium. Collectively, our data indicate that embryo-derived TNF promotes CPLA_2α phosphorylation and arachidonic acid release from luminal epithelium to induce fibroblast activation and decidualization.

The spectrum of in vitro maturation in clinical practice: the current insight

In vitro oocyte maturation (IVM) has been used worldwide. Despite the long-term implementation, the uptake of this procedure to complement current in vitro fertilization (IVF) remains low. The main reason is likely due to the non-synchronization of protocol and definition criteria, leading to difficulty in collective proper outcome data worldwide and, thus, lack of understanding of the exact IVM procedure. The review aims to consolidate the current clinical practice of IVM by dissecting relevant publications to be tailored for a current spectrum of clinical practice. Nevertheless, the background theories of oocyte maturation were also explored to provide a comprehensive understanding of the basis of IVM theories. Additional discussion of other potential uses of IVM in the future, such as in ovarian tissue cryopreservation known as OTO-IVM for fertility preservation and among women with diminished ovarian reserve, was also explored. Otherwise, future collaboration among all IVM centers is paramount for better collection of clinical data to provide valid recommendations for IVM in clinical practice, especially in molecular integrity and possible DNA alteration if present for IVM offspring outcome safety purposes.

Ovulatory-cycle frozen embryo transfer: spontaneous or triggered ovulation and the impact of LH elevation at hCG triggering

The effect of the luteinizing hormone (LH) elevation before the human chorionic gonadotropin (hCG) trigger in ovulatory frozen-thawed embryo transfer (Ovu-FET) cycles has not been determined. We aimed to investigate whether triggering ovulation in Ovu-FET cycles affects the live birth rate (LBR), and the contribution of elevated LH at the time of hCG trigger. This retrospective study included Ovu-FET cycles performed in our center from August 2016 to April 2021. Modified Ovu-FET (hCG trigger) and true Ovu-FET (without hCG trigger) were compared. The modified group was divided according to whether hCG was administered, before or after LH increased to > 15 IU/L and was twice the baseline value. The modified (n = 100) and true (n = 246) Ovu-FET groups and both subgroups of the modified Ovu-FET, those who were triggered before (n = 67) or after (n = 33) LH elevation, had comparable characteristics at baseline. Comparison of true vs. modified Ovu-FET outcomes revealed similar LBR (35.4% vs. 32.0%; P = 0.62), respectively. LBR were similar between the modified Ovu-FET subgroups regardless of the hCG trigger timing (31.3% before vs. 33.3% after LH elevation; P = 0.84). In conclusion, LBR of Ovu-FET were not affected by hCG trigger or whether LH was elevated at the time of hCG trigger. These results add reassurance regarding hCG triggering even after LH elevation.

Fractalkine Improves the Expression of Endometrium Receptivity-Related Genes and Proteins at Desferrioxamine-Induced Iron Deficiency in HEC-1A Cells

Fractalkine (CX3CL1/FKN) is a unique chemokine belonging to the CX3C chemokine subclass. FKN exists in two forms: a membrane-bound form expressed by both endometrium cells and trophoblasts thought to be implicated in maternal-fetal interaction and a soluble form expressed by endometrium cells. Endometrium receptivity is crucial in embryo implantation and a complex process regulated by large numbers of proteins, e.g., cytokines, progesterone receptor (PR), SOX-17, prostaglandin receptors (PTGER2), and tissue inhibitors of metalloproteinases (TIMPs). It has also been reported that iron is important in fertility and affects the iron status of the mother. Therefore, iron availability in the embryo contributes to fertilization and pregnancy. In this study, we focused on the effect of iron deficiency on the secreted cytokines (IL-6, IL-1β, leukocyte inhibitory factor, TGF-β), chemokines (IL-8, FKN), and other regulatory proteins (bone morphogenic protein 2, activin, follistatin, PR, SOX-17, prostaglandin E2 receptor, TIMP2), and the modifying effect of FKN on the expression of these proteins, which may improve endometrium receptivity. Endometrial iron deficiency was mediated by desferrioxamine (DFO) treatment of HEC-1A cells. FKN was added to the cells 24 h and 48 h after DFO with or without serum for modelling the possible iron dependence of the alterations. Our findings support the hypothesis that FKN ameliorates the effects of anemia on the receptivity-related genes and proteins in HEC-1A cells by increasing the secretion of the receptivity-related cytokines via the fractalkine receptor (CX3CR1). FKN may contribute to cell proliferation and differentiation by regulating activin, follistatin, and BMP2 expressions, and to implantation by altering the protein levels of PR, SOX-17, PTGER2, and TIMP2. FKN mitigates the negative effect of iron deficiency on the receptivity-related genes and proteins of HEC-1A endometrium cells, suggesting its important role in the regulation of endometrium receptivity.

Protease secretions by the invading blastocyst induce calcium oscillations in endometrial epithelial cells via the protease-activated receptor 2

BACKGROUND

Early embryo implantation is a complex phenomenon characterized by the presence of an implantation-competent blastocyst and a receptive endometrium. Embryo development and endometrial receptivity must be synchronized and an adequate two-way dialogue between them is necessary for maternal recognition and implantation. Proteases have been described as blastocyst-secreted proteins involved in the hatching process and early implantation events. These enzymes stimulate intracellular calcium signaling pathways in endometrial epithelial cells (EEC). However, the exact molecular players underlying protease-induced calcium signaling, the subsequent downstream signaling pathways and the biological impact of its activation remain elusive.

METHODS

To identify gene expression of the receptors and ion channels of interest in human and mouse endometrial epithelial cells, RNA sequencing, RT-qPCR and in situ hybridization experiments were conducted. Calcium microfluorimetric experiments were performed to study their functional expression.

RESULTS

We showed that trypsin evoked intracellular calcium oscillations in EEC of mouse and human, and identified the protease-activated receptor 2 (PAR2) as the molecular entity initiating protease-induced calcium responses in EEC. In addition, this study unraveled the molecular players involved in the downstream signaling of PAR2 by showing that depletion and re-filling of intracellular calcium stores occurs via PLC, IP₃R and the STIM1/Orai1 complex. Finally, in vitro experiments in the presence of a specific PAR2 agonist evoked an upregulation of the 'Window of implantation' markers in human endometrial epithelial cells.

CONCLUSIONS

These findings provide new insights into the blastocyst-derived protease signaling and allocate a key role for PAR2 as maternal sensor for signals released by the developing blastocyst.

Rhythm of the First Language: Dynamics of Extracellular Vesicle-Based Embryo-Maternal Communication in the Pre-Implantation Microenvironment

One of the most critical steps in mammalian reproduction is implantation. Embryos with an impaired capacity for embryo-maternal crosstalk are thought to have a reduced potential for implantation. One agent of embryo-maternal communication is extracellular vesicles (EV). EVs are lipid bilayer-bound biological nanoparticles implicated in intercellular communication between many of the known cell types. In the current study, we isolated EVs from trophoblast analogue JAr spheroids and supplemented the EVs with receptive endometrium analogue RL95-2 cells to simulate pre-implantation embryo-maternal dialogue. The transcriptome of the endometrial cells was examined at 30 min, 4 h and 48 h intervals using Oxford Nanopore^® technology. At the time points, 30 min, 4 h and 48 h, the endometrial cells showed a significantly altered transcriptome. It seems trophoblast EVs induce a swift and drastic effect on the endometrial transcriptome. The effect peaks at around 4 h of EV supplementation, indicating a generalized effect on cell physiology. Alterations are especially apparent in biological pathways critical to embryonic implantation, such as extracellular matrix-receptor interactions and cytokine-receptor interactions. These observations can be helpful in elucidating the dynamics of embryo-maternal communication in the pre-implantation period.

Interplay of "leukemia inhibitory factor receptor gene" (rs3099124) polymorphism, leukemia inhibitory factor and ovarian steroids with unexplained infertility

OBJECTIVE OF THE STUDY

To explore the association of leukemia inhibitory factor receptor (LIFR) gene variant rs3099124, ovarian steroids, and leukemia inhibitory factor with unexplained infertility in Pakistani females.

METHODOLOGY

A case-control investigation in which eighty-one (81) females with unexplained infertility and one hundred and sixty-two (162) fertile counterparts (age and body mass index compared) were recruited between October 2016 and 2018. Ten milliliters of venous blood was collected from all participants. "Genomic DNA" was taken out from lymphocytes in peripheral blood samples. "Tetra Amplification Refractory Mutation System Polymerase Chain Reaction (T-ARMS-PCR)" was constructed through software "Primer-I". Amplification was carried out by "T-ARMS-PCR" followed by subsequent sequencing for confirmation and extensive consonance. Estradiol, Progesterone and Leukemia Inhibitory Factor (LIF) were measured in serum by ELISA.

RESULTS

Statistically significant difference was noticed in genotype frequency in "LIFR-gene variant; rs3099124" (χ² = 28.222, P value < 0.01) between research participants. Although, rs "3099124" "AA" (OR = 0.000; 95%CI = 0-0) and "GA" genotypes (OR = 0.525; 95%CI = 0.226-1.22) showed non-significant safety/protection against unexplained infertility yet minor/risk allele "A" frequency was greater in women with unexplained infertility suggesting a possible explanation of implantation failure. LIF concentration varied between fertile and infertile groups (χ² = 9.857, P < 0.05) revealing significant threat of unexplained infertility in women with decreased LIF concentration (OR = 2.316, 95%CI = 1.214-4.416). Progesterone was significantly related to unexplained infertility in both study groups (χ² = 20.347, P < 0.05). High progesterone reduced the possibility of unexplained infertility (OR = 0.306; 95% CI = 0.166-0.567).

CONCLUSION

LIFR gene variation (rs3099124) and reduced LIF secretion may cause implantation failure in women with unexplained infertility.

Embryonic β-Catenin Is Required for Priming of the Uterus to Implantation

Repeated implantation failure is a major cause of infertility among healthy women. Uterine β-catenin (CTNNB1) plays a critical role in implantation. However, the role of embryonic CTNNB1 during implantation remains unclear. We addressed this topic by analyzing mice carrying Ctnnb1-deficient (Ctnnb1^Δ/Δ) embryos. Ctnnb1^Δ/Δ embryos were produced by intercrossing mice bearing Ctnnb1-deficient eggs and sperms. We found that Ctnnb1^Δ/Δ embryos developed to the blastocyst stage; thereafter, they were resorbed, leaving empty decidual capsules. Moreover, leukemia inhibitory factor, a uterine factor essential for implantation, was undetectable in Ctnnb1^Δ/Δ blastocysts. Furthermore, CDX2, a transcription factor that determines the fate of trophectoderm cells, was not observed in Ctnnb1^Δ/Δ blastocysts. Intrauterine injection with uterine fluids (from control mice) and recombinant mouse leukemia inhibitory factor proteins rescued the uterine response to Ctnnb1^Δ/Δ blastocysts. These results suggest that embryonic CTNNB1 is required for the secretion of blastocyst-derived factor(s) that open the implantation window, indicating that the uterine response to implantation can be induced using supplemental materials. Therefore, our results may contribute to the discovery of a similar mechanism in humans, leading to a better understanding of the pathogenesis of repeated implantation failure.

Omics insights into extracellular vesicles in embryo implantation and their therapeutic utility

Implantation success relies on intricate interplay between the developing embryo and the maternal endometrium. Extracellular vesicles (EVs) represent an important player of this intercellular signalling through delivery of functional cargo (proteins and RNAs) that reprogram the target cells protein and RNA landscape. Functionally, the signalling reciprocity of endometrial and embryo EVs regulates the site of implantation, preimplantation embryo development and hatching, antioxidative activity, embryo attachment, trophoblast invasion, arterial remodelling, and immune tolerance. Omics technologies including mass spectrometry have been instrumental in dissecting EV cargo that regulate these processes as well as molecular changes in embryo and endometrium to facilitate implantation. This has also led to discovery of potential cargo in EVs in human uterine fluid (UF) and embryo spent media (ESM) of diagnostic and therapeutic value in implantation success, fertility, and pregnancy outcome. This review discusses the contribution of EVs in functional hallmarks of embryo implantation, and how the integration of various omics technologies is enabling design of EV-based diagnostic and therapeutic platforms in reproductive medicine.

Effect of acupuncture on the opening time of implantation window and endometrial receptivity in controlled ovarian hyperstimulation rats during peri-implantation period

PURPOSE

To investigate the effect of acupuncture for improving the pregnancy rate of COH rats from the viewpoint of regulating the opening time of the implantation window and endometrial receptivity.

METHODS

Experimental rats were randomly divided into normal group (N), model group (M) and acupuncture group(A), and samples were collected on Day 4, 5 and 6 after mating. COH rats were treated with acupuncture at SP6, LR3, and ST36 once a day for 7 times. The pinopodes were observed under a scanning electron microscope. Serum estrogen and progesterone levels were measured via ELISA. The protein and mRNA levels of estrogen receptor (ER), progesterone receptor (PR), leukemia inhibitory factor (LIF), integrin β3, vascular endothelial growth factor (VEGF), and fibroblast growth factor 2 (FGF-2) in the endometrium were evaluated via West-blot, immunohistochemistry, and PCR.

RESULTS

Compared with group N, the pregnancy rate of group M was significantly decreased (P<0.05), and the abnormal serum hormone levels and implantation window advancement were observed. Compared with group M, the pregnancy rate of group A was significantly increased (P<0.05), the supraphysiological serum progesterone levels were restored to normalcy (P<0.05), and the advanced implantation window was restored to a certain extent. Further, the abnormal ER, PR, LIF, integrin β3, VEGF, and FGF-2 expression levels of the endometrium got recovered to varying degrees.

CONCLUSION

Acupuncture may restore the estrogen and progesterone balance in COH rats and the forward shift of the implantation window to a certain extent, improving the endometrial receptivity and finally improving the pregnancy rate of COH rats.

The role of thyroid function in female and male infertility: a narrative review

PURPOSE

We herein aimed to review the new insights into the impact of impaired thyroid function on male and female fertility, spacing from spontaneous pregnancy to ART, with the objective of providing an updated narrative revision of the literature.

METHODS

This narrative review was performed for all available prospective, retrospective and review articles, published up to 2021 in PubMed. Data were extracted from the text and from the tables of the manuscript.

RESULTS

Thyroid dysfunction is frequently associated with female infertility, whereas its link with male infertility is debated. Female wise, impaired function is detrimental to obstetric and fetal outcomes both in spontaneous pregnancies and in those achieved thanks to assisted reproduction technologies (ART). Furthermore, the reference range of TSH in natural pregnancy and ART procedures has recently become a matter of debate following recent reports in this field. On the other hand, the impact of thyroid function on the male reproductive system is less clear, although a possible role is suggested via modulation of Sertoli and Leydig cells function and spermatogenesis.

CONCLUSION

Thyroid function should be carefully monitored in both male and female, in couples seeking spontaneous pregnancy as well as ART, as treatment is generally immediate and likely to improve chances of success.

Ultrasound Molecular Imaging of Neovascularization for Evaluation of Endometrial Receptivity Using Magnetic iRGD-Modified Lipid-Polymer Hybrid Microbubbles

BACKGROUND

Angiogenesis plays an important role in endometrial receptivity, determining the response of the endometrium to the blastocyst at the early stage of embryo implantation. During the application of assisted reproduction technologies, it is very important to evaluate the status of uterine angiogenesis before deciding on embryo implantation. Targeted microbubbles (MBs)-based ultrasound molecular imaging (UMI) can noninvasively detect the expression status of biomarkers at the molecular level, thereby being a potential diagnosis strategy for various diseases and their therapeutic evaluation.

METHODS

The iRGD-lipopeptide (DSPE-PEG2000-iRGD) conjugate was prepared with iRGD peptides and DSPE-PEG2000-maleimide through the Michael-type addition reaction. Then, the magnetic iRGD-modified lipid-polymer hybrid MBs (Mag-iLPMs) were prepared with the double-emulsification-solvent-evaporation method. Magnetic targeting of Mag-iLPMs was confirmed under the microscope, followed by a rectangular magnet. Next, the in vitro targeted binding of MBs to murine brain-derived endothelial cells.3 (bEnd.3) and human umbilical vein endothelial cells (HUVEC) were evaluated. The ratio of MBs binding to bEnd.3 and HUVEC at the same field was also compared. For in vivo studies, bolus injections of targeted or control MBs were randomly administrated to non-pregnant or pregnant rats on day 5. Then, the uteri were imaged using a VisualSonics Vevo 2100 ultrasound system (Fujifilm VisualSonics Inc., Ontario, Canada) equipped with a high-frequency transducer. Ultrasonic imaging signals were acquired from Mag-iLPMs, and compared with Mag-LPMs, iLPMs, and LPMs.

RESULTS

The Mag-iLPMs showed excellent performance in ultrasound contrast imaging and binding affinity to target cells. Using the magnetic field, 10.5- and 12.47-fold higher binding efficiency to bEnd.3 and HUVEC were achieved compared to non-magnetic iLPMs, respectively. Significantly enhanced UMI signals were also observed in the uteri of rats intravenously injected pregnant rats (6.58-fold higher than rats injected with iLPMs).

CONCLUSION

We provided a powerful ultrasonic molecular functional imaging tool for uterine angiogenesis evaluation before embryonic implantation.

Commercially Available Molecular Approaches to Evaluate Endometrial Receptivity: A Systematic Review and Critical Analysis of the Literature

Despite the advances in the field of reproductive medicine, implantation failure represents a challenging condition affecting 10-30% of patients subjected to in vitro fertilization (IVF). Research has focused on the identification of molecules playing crucial roles in endometrial receptivity, with the aim of designing predictive tools for efficient detection of the implantation window. To that end, novel molecular genomic and transcriptomic approaches have been introduced as promising tools to enable personalized approaches with the aim of optimizing embryo transfer dating. However, the clinical value of these approaches remains unclear. The aim of this study is to provide a systematic review and critical analysis of the existing evidence regarding the employment of commercially available novel approaches to evaluate endometrial receptivity. An Embase and PubMed/Medline search was performed on 1 February 2022. From the 475 articles yielded, only 27 were included and analyzed. The considerable heterogeneity of the included articles indicates the uniqueness of the implantation window, showcasing that the optimal time for embryo transfer varies significantly between women. Moreover, this study provides information regarding the technical aspects of these advanced molecular tools, as well as an analysis of novel possible biomarkers for endometrial receptivity, providing a basis for future research in the field.

Inflammation-Related Molecules at the Maternal–Fetal Interface during Pregnancy and in Pathologically Altered Endometrium

The blastocyst expresses paternally derived alloantigens and induces inflammation during implantation. However, it is necessary for the onset of pregnancy. An abnormal response might result in a pathological course of pregnancy or pregnancy failure. On the other hand, a state of maternal immune tolerance is necessary to ensure the normal development of pregnancy by suppressing inflammatory processes. This article discusses recognized mechanisms and the significance of inflammatory processes for embryo implantation and pregnancy establishment. We would also like to present disorders involving excessive inflammatory response and their influence on events occurring during embryo implantation. The chain of correlation between the processes responsible for embryo implantation and the subsequent physiological course of pregnancy is complicated. Many of those interrelationships are still yet to be discovered. Undoubtedly, their recognition will give hope to infertile couples for the emergence of new treatments that will increase the chance of giving birth to a healthy child.

Three-dimensional culture models of human endometrium for studying trophoblast-endometrium interaction during implantation

During implantation, a symphony of interaction between the trophoblast originated from the trophectoderm of the implanting blastocyst and the endometrium leads to a successful pregnancy. Defective interaction between the trophoblast and endometrium often results in implantation failure, pregnancy loss, and a number of pregnancy complications. Owing to ethical concerns of using in vivo approaches to study human embryo implantation, various in vitro culture models of endometrium were established in the past decade ranging from two-dimensional cell-based to three-dimensional extracellular matrix (ECM)/tissue-based culture systems. Advanced organoid systems have also been established for recapitulation of different cellular components of the maternal-fetal interface, including the endometrial glandular organoids, trophoblast organoids and blastoids. However, there is no single ideal model to study the whole implantation process leaving more research to be done pursuing the establishment of a comprehensive in vitro model that can recapitulate the biology of trophoblast-endometrium interaction during early pregnancy. This would allow us to have better understanding of the physiological and pathological process of trophoblast-endometrium interaction during implantation.

Systemic vascular resistance may influence the outcome of in vitro fertilization

Introduction: The number of pregnancies obtained through in vitro fertilization (IVF) techniques are increasing, and only few studies have investigated hemodynamic variations in women undergoing IVF techniques. The aim of this study was to evaluate the hemodynamic parameters in women undergoing IVF, to assess a possible correlation between hemodynamics and embryo implantation.Methods: 45 normotensive non-obese women, age ≤ 43 years, with idiopathic or tubal infertility, referred to the Reproductive Physiopathology and Andrology Unit, Sandro Pertini Hospital, Rome, during the period 2020/2021, underwent IVF techniques. All women were evaluated with Ultra Sonic Cardiac Output Monitor (USCOM) to detect hemodynamic parameters at two different stages: at the mid-luteal phase, before the beginning of IVF, and at the day of embryo transfer (dET). All demographics and hormonal parameters in both groups were comparable. The hemodynamic parameters were compared between women with a positive β-HCG test vs. those testing negative.Results: 11 out of 45 (24,5%) women obtained positive β-HCG test. All demographics and hormonal parameters were comparable in both groups. Women with a positive β-HCG test showed statistically lower systemic vascular resistance (SVR) at mid-luteal phase (868.61 ± 100.1 vs. 1009 ± 168.4) and dET (818,9 ± 104.5 vs 1038.52 ± 150.82 dynes × s/cm⁵).Conclusions: Hemodynamic assessment can identify a more favorable pre-pregnancy cardiovascular adaptation. Embryo implantation might be positively influenced by the hemodynamic parameters, e.g. lower SVR, before the beginning of IVF techniques, and during the window of implantation.

Effectiveness of phosphodiesterase type 5 inhibitors on the treatment of thin endometrium and pregnancy outcomes: An systematic review

Phosphodiesterase type 5 (PDE5) inhibitors are thought to play a role in increasing endometrial thickness and increasing the success rate of pregnancy outcomes. This study was done to investigate the effects of PDE5 inhibitors on infertile women with thin endometrium and pregnancy outcomes. In this systematic review, all randomized controlled trials (RCTs) and observational studies were retrieved from databases including Institute for Scientific Information (ISI), PubMed, and Scopus by interesting keywords. A checklist was designed to collect necessary data and pregnancy outcomes, and the required items were recorded. PDE5 inhibitors through various mechanisms such as induction of vasodilatory effect through the effect on NO/cGMP signaling on vascular smooth muscle, through regulating cells proliferation and induction angiogenesis by increasing the expression of tumor suppressor factor (p53), and vascular endothelial growth factor A (VEGF-A) and downregulating inflammation by downregulating proinflammatory cytokines, affect endometrial thickness that eventually increases and pregnancy outcomes. Although PDE5s inhibitors increase endometrial thickness by different mechanisms, especially in women with thin endometrial, this does not necessarily mean that they induce a positive effect in all situations. However, their positive effects on pregnancy outcome may be affected by the time of administration, type of infertility treatment, underlying diseases such as pelvic disorders and inflammation. So in this regard, there are still ambiguous aspects that required further RCTs study in this area.