Extracellular vesicle mediated embryo-endometrial cross talk during implantation and in pregnancy

Unlocking a Decade of Research on Embryo-Derived Extracellular Vesicles: Discoveries Made and Paths Ahead

Over the past decade, research on embryo-derived extracellular vesicles (EVs) has unveiled their critical roles in embryonic development and intercellular communication. EVs secreted by embryos are nanoscale lipid bilayer vesicles that carry bioactive cargo, including proteins, lipids, RNAs, and DNAs, reflecting the physiological state of the source cells. These vesicles facilitate paracrine and autocrine signaling, influencing key processes such as cell differentiation, embryo viability, and endometrial receptivity. Studies reveal that EVs can traverse the zona pellucida, transferring molecular signals that enhance blastocyst formation and support embryo-maternal crosstalk. EVs have emerged as non-invasive biomarkers for embryo quality, with their cargo providing insights into genetic integrity and developmental competence. Advances in isolation and characterization techniques have identified specific microRNA (miRNAs) and transcription factors within EVs, offering potential for use in preimplantation genetic screening (PGS) and sex determination. Moreover, EV-mediated interactions with the maternal environment are critical for successful implantation, as they modulate gene expression and immune responses in endometrial and oviductal cells. Despite these advancements, challenges persist, including the standardization of EV isolation methods and the low yield of EVs DNA from spent culture media. Future research should aim to refine analytical techniques, explore EV-miRNA profiling, and investigate the mechanisms underlying EV-mediated signaling. By addressing these gaps, EVs could revolutionize embryo selection and reproductive technologies, offering new strategies to improve outcomes in assisted reproduction and animal breeding.

Thalassemia and assisted reproduction: non-transfusion-dependent thalassemia shows no significant effect on live birth rates after embryo transfer

Background

Thalassemia is a hereditary blood disorder that can impact fertility due to various factors such as iron overload and endocrine disruption. While the effects of iron overload on fertility outcomes in transfusion-dependent thalassemia (TDT) have been well-documented, there is limited data on how NTDT affects assisted reproductive technology (ART) outcomes. This study aims to assess the fertility and pregnancy outcomes of NTDT patients compared to thalassemia carriers (TC) patients in IVF and frozen embryo transfer (FET) cycles.

Methods

This retrospective cohort study analyzed 6,911 female patients who underwent autologous IVF treatment at a private reproductive center between January 2013 and December 2022. The study included women who were carriers of thalassemia or diagnosed with NTDT. ART outcomes, including oocyte retrieval rate, embryo development (maturation rate, number of fertilized oocytes and blastocyst formation rate), clinical pregnancy rate, live birth rate, and miscarriage rate, were compared between NTDT and TC patients. Propensity score matching (PSM) and multivariable adjustments for potential confounders were applied in the statistical analyses.

Results

NTDT patients had a significantly lower oocyte retrieval rate (0.88 vs. 0.93, p < 0.05) and a longer interval from medication initiation to oocyte retrieval (13.35 days vs. 12.38 days, p < 0.05) compared to TC patients. However, NTDT patients exhibited higher oocyte maturation rates and a greater number of fertilized oocytes. Despite these differences in embryo development metrics, there were no statistically significant differences in clinical pregnancy rates and live birth rates between NTDT and TC patients in both fresh embryo transfer (IVF-ET) and FET cycles (p > 0.05). These findings suggest that while NTDT may affect certain aspects of embryo development, it does not significantly impact overall pregnancy outcomes in ART.

Conclusion

This study provides valuable insights into ART outcomes for NTDT patients, showing that, despite challenges in oocyte retrieval, their fertility and pregnancy outcomes are comparable to those of thalassemia carriers. Clinicians should consider individualized treatment plans and provide comprehensive counseling for NTDT patients, focusing on their specific fertility characteristics, to optimize ART outcomes. Further research is needed to explore the underlying mechanisms affecting embryo development in NTDT patients and to confirm these findings in broader populations.

Regulatory roles of extracellular vesicles in pregnancy complications

BACKGROUND

Extracellular vesicles (EVs) are heterogeneous membranous structures released by various cell types, including large vesicles, microvesicles (MVs), and exosomes. These vesicles play crucial roles in intercellular communication within interstitial fluids and are involved in numerous physiological and pathological processes.

AIM OF REVIEW

This review aims to examine the regulatory roles of EVs in pregnancy complications, focusing on their involvement in gestational diabetes mellitus (GDM), preeclampsia (PE), and preterm birth (PTB).

KEY SCIENTIFIC CONCEPTS OF REVIEW

Placenta- and embryo-derived EVs have gained significant attention for their biological roles due to their effects on inflammation, immune response and immunomodulation. Recent research highlights the importance of EVs in embryonic development and gestation. During pregnancy, several EVs functioned in complex endocrine regulation and pregnancy complications that can affect both the mother and fetus, with long-term cardiovascular and metabolic risks. This review discusses the current evidence on how EVs modulate pregnancy outcomes and explores their biological roles in the pathology of GDM, PE, and PTB. In spite of the current difficulties in relating these findings to the pathogenesis of pregnancy complications and the insufficient evidence for clinical practice, the potential impact of specific proteins and miRNAs transported by EVs is noteworthy on the emergence of pregnancy complications. Future research should continue to explore the complex interactions mediated by EVs to develop novel diagnostic and therapeutic strategies for pregnancy-related disorders.

Extracellular Vesicles in Implantation: Cross-Talk Between the Embryo and Endometrium

Extracellular vesicles (EVs), including exosomes and microvesicles, have emerged as pivotal mediators of intercellular communication. Embryo implantation is a critical process in early pregnancy and requires communication between the embryo and maternal uterus. EVs are important in coordinating the communication between the embryo and maternal uterus. This review explores EV biogenesis, molecular composition, and functional roles during implantation. It emphasizes the dynamic role of EVs in modulating the maternal-embryo dialogue, which is critical for establishing a receptive endometrium and facilitating successful implantation. EVs secreted by the embryo and endometrial cells have been shown to carry a diverse cargo of proteins, lipids, and miRNAs, which collectively influence key physiological processes, including immune tolerance, endometrial receptivity, and trophoblast invasion. EVs can be potential candidates as non-invasive biomarkers to assess the quality of embryos and uterine receptivity to enhance reproductive success. By providing a comprehensive overview of the current understanding of EVs in implantation, this chapter aims to highlight the significance of EVs in reproductive biology and their potential applications in improving fertility rates.

Prenatal Triphenyl Phosphate Exposure and Hyperlipidemia in Offspring: Role of Trophoblast-Derived Extracellular Vesicle PPARγ

Triphenyl phosphate (TPhP) is a widely used organophosphate flame retardant, the health risks of TPhP are a global concern. In this study, we found that prenatal TPhP exposure at human relevant concentration induced hyperlipidemia in male offspring, it increased serum levels of triglyceride, total cholesterol, and low-density lipoprotein cholesterol. Placental trophoblast-derived extracellular vesicles (T-EVs) could transport to the fetus through maternal-fetal circulation. TPhP significantly upregulated the protein level of peroxisome proliferator activated receptor γ (PPARγ) in T-EVs. Similar to TPhP, gestational exposure to T-EVs isolated from TPhP exposed mice placentae induced the same effects. While, gestational intervention with GW9662 (PPARγ inhibitor) or GW4869 (EVs secretion inhibitor) would alleviate the disturbed lipid metabolism induced by TPhP. Meanwhile, in vitro experiments verified that TPhP upregulated PPARγ in HTR8/SVneo cells derived EVs, and these EVs promoted adipogenesis in preadipocyte 3T3-L1 cells. Knock down of PPARγ in HTR8/SVneo could alleviate the adipogenensis effects of EVs derived from TPhP exposed HTR8/SVneo cells. These results demonstrate that TPhP exposure induces hyperlipidemia in male offspring by upregulating PPARγ in T-EVs. Our study provides new insights into the metabolic disruptive effects of TPhP, and emphasizes the mediating effects of placental T-EVs on gestational environmental stress in fetal development.

A "poly-matter network" conception of biological inheritance

Here we intend to shift the "DNA- and information-centric" conception of biological inheritance, with the accompanying exclusion of any non-DNA matter, to a "poly-matter network" framework which, in addition to DNA, considers the action of other cellular membranous constituents. These cellular structures, in particular organelles and plasma membranes, express "landscapes" of specific topologies at their surfaces, which may become altered in response to certain environmental factors. These so-called "membranous environmental landscapes" (MELs), which replicate by self-organization / autopoiesis rather than self-assembly, are transferred from donor to acceptor cells by various - vesicular and non-vesicular - mechanisms and exert novel features in the acceptor cells. The "DNA-centric" conception may be certainly explanatorily sufficient for the transfer of heritable phenotype variation to acceptor cells following the copying of DNA in donor cells and thereby for the phenomenon of biological inheritance of traits. However, it is not causally sufficient. With the observation of phenotype variation, as initially manifested during bacterial transformation, the impact of environmental factors, such as nutrition and stress, in the differential regulation of gene expression has been widely accepted and resulted in intense efforts to resolve the underlying epigenetic mechanisms. However, these are explained under a conceptual frame where the DNA (and associated proteins) are the only matter of inheritance. In contrast, it is our argumentation that inheritance can only be adequately understood as the transfer of DNA in concert with non-DNA matter in a "poly-matter network" conception. The adequate inclusion of the transfer of non-DNA matter is still a desideratum of future genetic research, which may pave the way for the experimental elucidation not only of how DNA and membrane matter act in concert to enable the inheritance of innate traits, but also whether they interact for that of acquired biological traits. Moreover, the "poly-matter network" conception may open new perspectives for an understanding of the pathogenesis of "common complex" diseases.

Proteomic Profiles of Maternal Plasma Extracellular Vesicles for Prediction of Preeclampsia

PROBLEM

Preeclampsia is a heterogeneous syndrome of diverse etiologies and molecular pathways leading to distinct clinical subtypes. Herein, we aimed to characterize the extracellular vesicle (EV)-associated and soluble fractions of the maternal plasma proteome in patients with preeclampsia and to assess their value for disease prediction.

METHOD OF STUDY

This case-control study included 24 women with term preeclampsia, 23 women with preterm preeclampsia, and 94 healthy pregnant controls. Blood samples were collected from cases on average 7 weeks before the diagnosis of preeclampsia and were matched to control samples. Soluble and EV fractions were separated from maternal plasma; EVs were confirmed by cryo-EM, NanoSight, and flow cytometry; and 82 proteins were analyzed with bead-based, multiplexed immunoassays. Quantile regression analysis and random forest models were implemented to evaluate protein concentration differences and their predictive accuracy. Preeclampsia subgroups defined by molecular profiles were identified by hierarchical cluster analysis. Significance was set at p < 0.05 or false discovery rate-adjusted q < 0.1.

RESULTS

In preterm preeclampsia, PlGF, PTX3, and VEGFR-1 displayed differential abundance in both soluble and EV fractions, whereas angiogenin, CD40L, endoglin, galectin-1, IL-27, CCL19, and TIMP1 were changed only in the soluble fraction (q < 0.1). The direction of changes in the EV fraction was consistent with that in the soluble fraction for nine proteins. In term preeclampsia, CCL3 had increased abundance in both fractions (q < 0.1). The combined EV and soluble fraction proteomic profiles predicted preterm and term preeclampsia with an AUC of 78% (95% CI, 66%-90%) and 68% (95% CI, 56%-80%), respectively. Three clusters of preeclampsia featuring distinct clinical characteristics and placental pathology were identified based on combined protein data.

CONCLUSIONS

Our findings reveal distinct alterations of the maternal EV-associated and soluble plasma proteome in preterm and term preeclampsia and identify molecular subgroups of patients with distinct clinical and placental histopathologic features.

Extracellular vesicles affecting embryo development in vitro: a potential culture medium supplement

Extracellular vesicles (EVs) are nanometer-sized lipid bilayer vesicles released by cells, playing a crucial role in mediating cellular communication. This review evaluates the effect of EVs on early embryonic development in vitro by systematically searching the literature across three databases, Embase, PubMed, and Scopus, from inception (Embase, 1947; PubMed, 1996; and Scopus, 2004) to 30 June 2024. A total of 28 studies were considered relevant and included in this review. The EVs included in these investigations have been recovered from a range of sources, including oviduct fluid, follicular fluid, uterine fluid, seminal plasma, embryos, oviduct epithelial cells, endometrial epithelial cells, amniotic cells, and endometrial-derived mesenchymal stem cells collected primarily from mice, rabbits, cattle and pigs. This diversity in EV sources highlights the broad interest and potential applications of EVs in embryo culture systems. These studies have demonstrated that supplementation with EVs derived from physiologically normal biofluids and cells to the embryo culture medium system has positive effects on embryonic development. Conversely, EVs derived from cells under pathological conditions have shown a negative impact. This finding underscores the importance of the source and condition of EVs used in culture media. Further, the addition of EVs as a culture medium supplement holds significant therapeutic potential for optimizing in vitro embryo culture systems. In conclusion, this evaluation offers a thorough assessment of the available data on the role of EVs in embryo culture media and highlights the potential and challenges of using EVs in vitro embryo production.

Labeled extracellular vesicles can be found in the blood plasma shortly after intrauterine infusion in bovine

This study explored the migration of follicular fluid (FF)-derived extracellular vesicles (EVs) of the uterine environment to the bloodstream and their interaction with neutrophils in vivo and in vitro. For the in vivo experiment, six Nellore heifers (Bos indicus) received an intrauterine infusion seven days after ovulation with 1X PBS only (sham group; n=1), 1X PBS stained with lipophilic dye PKH26 (control group; n=2), or FF-derived EVs stained with PKH26 (treated group; n=3). Plasma was collected at 0, 10, 30, 60-, 180-, 360-, 720-, and 1440-min post-infusion to obtained EVs for analysis by nano flow cytometry. Labeled EVs were present in the bloodstream at 30- and 60-min post-infusion in the treatment group. Additionally, plasma derived-EVs from all groups were positive for Calcein-AM, Alix, Syntenin, and Calnexin, which confirm the presence of EVs. The second experiment utilized the plasma-derived EVs from the heifers from 30 and 60 min timepoints to evaluate if neutrophils can uptake EVs in vitro. As results, it was possible to observe the presence of labeled EVs in neutrophils treated with plasma derived-EVs from the treatment group. In summary, our results suggest that labeled EVs can migrate from the uterine environment rapidly and interact with circulating immune cells in bovine.

From Germ Cells to Implantation: The Role of Extracellular Vesicles

Extracellular vesicles represent a large heterogeneous class of near and long-distance intercellular communication mediators, released by both prokaryotic and eukaryotic cells. Specifically, the scientific community has shown growing interest in exosomes, which are nano-sized vesicles with an endosomal origin. Not so long ago, the physiological goal of exosome generation was largely unknown and required more investigation; at first, it was hypothesized that exosomes are able to remove excess, reject and unnecessary constituents from cells to preserve cellular homeostasis. However, thanks to recent studies, the central role of exosomes in regulating cellular communication has emerged. Exosomes act as vectors in cell-cell signaling by their cargo, proteins, lipids, and nucleic acids, and influence physiological and pathological processes. The findings on exosomes are widespread in a large spectrum of biomedical applications from diagnosis and prognosis to therapies. In this review, we describe exosome biogenesis and the current methods for their isolation and characterization, emphasizing the role of their cargo in female reproductive processes, from gametogenesis to implantation, and the potential involvement in human female disorders.

The evolving roles of extracellular vesicles in embryo-maternal communication

Mammalian reproduction relies on precise maternal-fetal communication, wherein immune modifications foster tolerance toward the semi-allogeneic embryo. Extracellular vesicles (EVs), including exosomes and microvesicles, have emerged as crucial mediators, transporting molecules like microRNAs securely. EVs influence various reproductive stages, from gamete maturation to implantation, and impact pathologies like pregnancy loss. In the embryo-maternal dialogue, EVs notably affect oviductal interactions, gene expression, and the embryo-endometrial interface, crucial for successful implantation. Key queries persist about EV uptake, cargo delivery, and the specific biomolecules driving communication. Their potential in diagnostics, therapeutics, and understanding environmental impacts on fertility signals an exciting future, reliant on collaborative efforts for transformative strides in reproductive health.

Effect of 3D and 2D cell culture systems on trophoblast extracellular vesicle physico-chemical characteristics and potency

The growing understanding of the role of extracellular vesicles (EVs) in embryo-maternal communication has sparked considerable interest in their therapeutic potential within assisted reproductive technology, particularly in enhancing implantation success. However, the major obstacle remains the large-scale production of EVs, and there is still a gap in understanding how different culture systems affect the characteristics of the EVs. In the current study, trophoblast analogue human chorionic carcinoma cell line was cultivated in both conventional monolayer culture (2D) and as spheroids in suspension culture (3D) and how the cell growth environment affects the physical, biochemical and cellular signalling properties of EVs produced by them was studied. Interestingly, the 3D system was more active in secreting EVs compared to the 2D system, while no significant differences were observed in terms of morphology, size, and classical EV protein marker expression between EVs derived from the two culture systems. There were substantial differences in the proteomic cargo profile and cellular signalling potency of EVs derived from the two culture systems. Notably, 2D EVs were more potent in inducing a cellular response in endometrial epithelial cells (EECs) compared to 3D EVs. Therefore, it is essential to recognize that the biological activity of EVs depends not only on the cell of origin but also on the cellular microenvironment of the parent cell. In conclusion, caution is warranted when selecting an EV production platform, especially for assessing the functional and therapeutic potential of EVs through in vitro studies.

Extracellular Vesicles: the Next Frontier in Pregnancy Research

Extracellular vehicles (EVs) have been involved in several aspects of pregnancy, including endometrial receptivity, embryo implantation, and embryo-maternal communication showing them associated with pregnancy disorders, such as preeclampsia, gestational diabetes mellitus, and preterm birth. Further research is warranted to fully comprehend the exact pathophysiological roles of EVs and to develop new therapies targeting EVs thereby improving pregnancy outcomes. Herein, we review the recent knowledge on the multifaceted roles of EVs during pregnancy and address the majority of the molecular interactions between EVs, maternal, and fetal cells with an emphasis on disorders of pregnancy under the influence of EVs. Moreover, we also discuss its applications in clinical trials followed by prospects.

The role of extracellular vesicles from placenta and endometrium in pregnancy: Insights from tumor biology

Extracellular vesicles (EVs) are small membrane-bound particles secreted by various cell types that play a critical role in intercellular communication by packaging and delivering biomolecules. In recent years, EVs have emerged as essential messengers in mediating physiological and pathological processes in tumor biology. The tumor microenvironment (TME) plays a pivotal role in tumor generation, progression, and metastasis. In this review, we provide an overview of the impact of tumor-derived EVs on both tumor cells and the TME. Moreover, we draw parallels between tumor biology and pregnancy, as successful embryo implantation also requires intricate intercellular communication between the placental trophecepiblast and the endometrial epithelium. Additionally, we discuss the involvement of EVs in targeting immune responses, trophoblast invasion, migration, and angiogenesis, which are shared biological processes between tumors and pregnancy. Specifically, we highlight the effects of placenta-derived EVs on the fetal-maternal interface, placenta, endometrium, and maternal system, as well as the role of endometrium-derived EVs in embryo-endometrial communication. However, challenges still exist in EVs research, including the standardization of EVs isolation methods for diagnostic testing, which also apply to reproductive systems where EVs-mediated communication is proposed to take place. Through this review, we aim to deepen the understanding of EVs, particularly in the context of reproductive biology, and encourage further investigation in this field.

Exosomes as modulators of embryo implantation

Exosomes, known as extracellular vehicles (EVs), are found in biological fluids. They have the capability to carry and transfer signaling molecules, such as nucleic acids and proteins, facilitating intercellular communication and regulating the gene expression profile in target cells. EVs have the potential to be used as biomarkers in diagnosis, prognosis and also as feasible therapeutic targets. The available evidence suggests that exosomes play critical roles in the reproductive system, particularly during implantation, which is widely recognized as a crucial step in early pregnancy. A proper molecular dialogue between a high-quality embryo and a receptive endometrium is essential for the establishment of a normal pregnancy. This review focuses on the key role of exosomes originated from various sources, including the embryo, seminal fluid, and uterus fluid, based on the available evidence. It explores their potential applications as a novel approach in assisted reproductive technologies (ART).

Breaking the silence: The role of extracellular vesicles in unraveling the diagnosis and treatment of endometriosis

Cell-to-cell communication is believed to be facilitated by membrane-bound vesicles called extracellular vesicles (EVs), which are released by cells. Protein, lipids, and nucleic acids are major cargo of EVs and are transported in these vesicles. Depending on the parent and recipient cell types, they can affect a wide variety of biological processes in the tissues to which they are delivered. EVs are essential for embryo implantation and endometriosis, and they are located in the uterine cavities of different species, where they promote blastocyst and endometrial preparation for implantation. This review focuses on what is currently understood regarding pathologic and diagnostic characteristics, and the potential therapeutic value of EVs in the context of endometriosis, where they can be used for drug delivery and targeted therapy due to their ability to carry bioactive molecules to specific cells or tissues. The findings of this review highlight the potential for a wide range of clinical applications that involve endometrial EVs in the areas of treatment, such as surgical and pharmacological, diagnostic biomarker development, and drug delivery systems, all with the ultimate goal of improving pregnancy success rates.

Current knowledge on the role of extracellular vesicles in endometrial receptivity

Endometrial receptivity has been widely understood as the capacity of the endometrium to receive implantable embryos. The establishment of endometrial receptivity involves multiple biological processes including decidualization, tissue remodeling, angiogenesis, immune regulation, and oxidative metabolism. Extracellular vesicles (EVs) are lipid-bilayer-membrane nanosized vesicles mediating cell-to-cell communication. Recently, EVs and their cargo have been proven as functional factors in the establishment of endometrial receptivity. In this review, we comprehensively summarized the alteration of endometrium/embryo-derived EVs during the receptive phase and retrospected the current findings which revealed the pivotal role and potential mechanism of EVs to promote successful implantation. Furthermore, we highlight the potentiality and limitations of EVs being translated into clinical applications such as biomarkers of endometrial receptivity or reproductive therapeutic mediators, and point out the direction for further research.

The Role of ncRNAs in the Immune Dysregulation of Preeclampsia

The main complications causing practically 75% of all maternal deaths are severe bleeding, infections, and high blood pressure during pregnancy (preeclampsia (PE) and eclampsia). The usefulness of ncRNAs as clinical biomarkers has been explored in an extensive range of human diseases including pregnancy-related diseases such as PE. Immunological dysregulation show that the Th1/17:Th2/Treg ratio is "central and causal" to PE. However, there is evidence of the involvement of placenta-expressed miRNAs and lncRNAs in the immunological regulation of crucial processes of placenta development and function during pregnancy. Abnormal expression of these molecules is related to immune physiopathological processes that occur in PE. Therefore, this work aims to describe the importance of miRNAs and lncRNAs in immune dysregulation in PE. Interestingly, multiple ncRNAS are involved in the immune dysregulation of PE participating in type 1 immune response regulation, immune microenvironment regulation in placenta promoting inflammatory factors, trophoblast cell invasion in women with Early-Onset PE (EOPE), placental development, and angiogenesis, promotion of population of M1 and M2, proliferation, invasion, and migration of placental trophoblast cells, and promotion of invasion and autophagy through vias such as PI3K/AKT/mTOR, VEGF/VEGFR1, and TLR9/STAT3.

Effects of extracellular vesicles derived from steroids-primed oviductal epithelial cells on porcine in vitro embryonic development

Extracellular vesicles (EVs) play an active role in regulating different physiological events, however, endocrine control of EVs cargo contents remain poorly understood. In this study, we aimed to isolate EVs from the porcine oviductal epithelial cells (POECs) that were primed with steroid hormones including estradiol (E2) and progesterone (P4), mimicking the in vivo conditions of the reproductive cycle and studied their effects on in vitro produced embryonic development. For this purpose, POECs were treated either with 0 concentration (control) or two different combinations of E2 and P4 including 50 pg/mL E2 + 0.5 ng/mL P4 (group H1), and 10 pg/mL E2 + 35 ng/mL P4 (group H2). Embryos were prepared after in vitro maturation either by parthenogenetic activation or somatic cell nuclear transfer (SCNT) technique. Treating parthenogenetic embryo with EVs, led a significantly higher rate of the blastocyst formation in the group supplemented with each EVs, compared to the control group. In addition, TUNEL assay and gene expression level analysis revealed that apoptosis was significantly reduced in the H2 EVs group. Furthermore, EVs from hormone-primed POECs improved the formation rate of porcine SCNT embryos compared to the control group. While in each EVs supplemented group (control EVs, H1 EVs, H2 EVs), the expression of cell reprogramming-related genes in cloned embryos showed a tendency of increase, the effect was stronger in H1 EVs and H2 EVs. In conclusion, EVs derived from POECs cultured in hormonal conditions simulating the in vivo environment had a positive effect on porcine blastocysts formation, which will likely facilitate in the production of cloned embryos.

Embryonic signals mediate extracellular vesicle biogenesis and trafficking at the embryo-maternal interface

BACKGROUND

Extracellular vesicles (EVs) are membrane-coated nanoparticles secreted by almost all cell types in living organisms. EVs, as paracrine mediators, are involved in intercellular communication, immune response, and several reproductive events, including the maintenance of pregnancy. Using a domestic animal model (Sus scrofa) with an epitheliochorial, superficial type of placentation, we focused on EV biogenesis pathway at the embryo-maternal interface, when the embryonic signaling occurs for maternal recognition and the maintenance of pregnancy.

RESULTS

Transmission electron microscopy was used during early pregnancy to visualize EVs and apocrine and/or merocrine pathways of secretion. Immunofluorescent staining localized proteins responsible for EV biogenesis and cell polarization at the embryo-maternal interface. The expression profiles of genes involved in biogenesis and the secretion of EVs pointed to the possible modulation of endometrial expression by embryonic signals. Further in vitro studies showed that factors of embryonic origin can regulate the expression of the ESCRT-II complex and EV trafficking within endometrial luminal epithelial cells. Moreover, miRNA-mediated rapid negative regulation of gene expression was abolished by delivered embryonic signals.

CONCLUSIONS

Our findings demonstrated that embryonic signals are potent modulators of ESCRT-dependent EV-mediated secretory activity of the endometrium during the critical stages of early pregnancy. Video Abstract.

First Trimester Prediction of Preterm Birth in Patient Plasma with Machine-Learning-Guided Raman Spectroscopy and Metabolomics

Preterm birth (PTB) is the leading cause of infant deaths globally. Current clinical measures often fail to identify women who may deliver preterm. Therefore, accurate screening tools are imperative for early prediction of PTB. Here, we show that Raman spectroscopy is a promising tool for studying biological interfaces, and we examine differences in the maternal metabolome of the first trimester plasma of PTB patients and those that delivered at term (healthy). We identified fifteen statistically significant metabolites that are predictive of the onset of PTB. Mass spectrometry metabolomics validates the Raman findings identifying key metabolic pathways that are enriched in PTB. We also show that patient clinical information alone and protein quantification of standard inflammatory cytokines both fail to identify PTB patients. We show for the first time that synergistic integration of Raman and clinical data guided with machine learning results in an unprecedented 85.1% accuracy of risk stratification of PTB in the first trimester that is currently not possible clinically. Correlations between metabolites and clinical features highlight the body mass index and maternal age as contributors of metabolic rewiring. Our findings show that Raman spectral screening may complement current prenatal care for early prediction of PTB, and our approach can be translated to other patient-specific biological interfaces.

Human blastocysts uptake extracellular vesicles secreted by endometrial cells containing miRNAs related to implantation

STUDY QUESTION

Are the extracellular vesicles (EVs) secreted by the maternal endometrium uptaken by human embryos and is their miRNA cargo involved in implantation and embryo development?

SUMMARY ANSWER

Data suggest that EVs secreted by human endometrial epithelial cells are internalized by human blastocysts, and transport miRNAs to modulate biological processes related to implantation events and early embryo development.

WHAT IS KNOWN ALREADY

Successful implantation is dependent on coordination between maternal endometrium and embryo, and EVs role in the required cell-to-cell crosstalk has recently been established. In this regard, our group previously showed that protein cargo of EVs secreted by primary human endometrial epithelial cells (pHEECs) is implicated in biological processes related to endometrial receptivity, embryo implantation, and early embryo development. However, little is known about the regulation of these biological processes through EVs secreted by the endometrium at a transcriptomic level.

STUDY DESIGN, SIZE, DURATION

A prospective descriptive study was performed. Endometrial biopsies were collected from healthy oocyte donors with confirmed fertility on the day of oocyte retrieval, 36 h after the LH surge. pHEECs were isolated from endometrial biopsies (n = 8 in each pool) and cultured in vitro. Subsequently, conditioned medium was collected and EVs were isolated and characterized. Uptake of EVs by human blastocysts and miRNA cargo of these EVs (n = 3 pools) was analyzed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

EVs were isolated from the conditioned culture media using ultracentrifugation, and characterization was performed using western blotting, nanoparticle tracking analysis, and transmission electron microscopy. EVs were fluorescently labeled with Bodipy-TR ceramide, and their uptake by human blastocysts was analyzed using confocal microscopy. Analysis of the miRNA cargo of EVs was performed using miRNA sequencing, target genes of the most expressed miRNA were annotated, and functional enrichment analysis was performed.

MAIN RESULTS AND THE ROLE OF CHANCE

EVs measured 100-300 nm in diameter, a concentration of 1.78 × 1011 ± 4.12 × 1010 (SD) particles/ml and expressed intraluminal protein markers Heat shock protein 70 (HSP70) and Tumor Susceptibility Gene 101 (TSG101), in addition to CD9 and CD81 transmembrane proteins. Human blastocysts efficiently internalized fluorescent EVs within 1-2 h, and more pronounced internalization was observed in the hatched pole of the embryos. miRNA-seq analysis featured 149 annotated miRNAs, of which 37 were deemed most relevant. The latter had 6592 reported gene targets, that in turn, have functional implications in several processes related to embryo development, oxygen metabolism, cell cycle, cell differentiation, apoptosis, metabolism, cellular organization, and gene expression. Among the relevant miRNAs contained in these EVs, we highlight hsa-miR-92a-3p, hsa-let-7b-5p, hsa-miR-30a-5p, hsa-miR-24-3p, hsa-miR-21-5p, and hsa-let-7a-5p as master regulators of the biological processes.

LIMITATIONS, REASONS FOR CAUTION

This is an in vitro study in which conditions of endometrial cell culture could not mimic the intrauterine environment.

WIDER IMPLICATIONS OF THE FINDINGS

This study defines potential biomarkers of endometrial receptivity and embryo competence that could be useful diagnostic and therapeutic targets for implantation success, as well as open insight further investigations to elucidate the molecular mechanisms implicated in a successful implantation.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Spanish Ministry of Education through FPU awarded to M.S.-B. (FPU18/03735), the Health Institute Carlos III awarded to E.J.-B. (FI19/00110) and awarded to H.F. by the Miguel Servet Program 'Fondo Social Europeo «El FSE invierte en tu futuro»' (CP20/00120), and Generalitat Valenciana through VALi+d Programme awarded to M.C.C.-G. (ACIF/2019/139). The authors have no conflicts of interest to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Effect of hyaluronic acid-enriched transfer medium on frozen-thawed embryo transfer outcomes in RIF patients: a single-centre retrospective study

Introduction

Many patients who undergo assisted reproductive technology (ART) suffer from recurrent implantation failure (RIF). The addition of hyaluronic acid (HA) to the transfer medium is one of several methods to improve pregnancy outcomes. We investigated whether HA could improve the live birth and clinical pregnancy rates of RIF patients.

Methods

This study included 248 RIF patients, who were divided into two groups: the control (CTL) group (n=137), which received transfer medium without HA, and the HA group (n=111), which received transfer medium with HA. The two groups were compared according to the ART outcome.

Results

The primary outcomes were the clinical pregnancy and live birth rates. Secondary outcomes include a positive urine pregnancy test, the implantation, ongoing pregnancy, multiple pregnancy, clinical miscarriage, and ectopic pregnancy rates, foetal or congenital defects, obstetric complications, infant birth weight and any related adverse events. Regarding the primary outcomes, the clinical pregnancy rate was significantly higher in the HA group than in the control group, and there was no significant difference in the live birth rate (LBR) between the HA and control groups. Regarding the secondary outcomes, the implantation, multiple pregnancy and ectopic pregnancy rates were similar between the two groups.

Discussion

Our findings supported the conclusion that HA can improve the clinical pregnancy rate of patients with RIF undergoing FET cycles, but the live birth rate was not significantly improved with the addition of HA to the traditional transfer medium.

Sperm-borne microRNA-34c regulates maternal mRNA degradation and preimplantation embryonic development in mice

BACKGROUND

Studies have shown that sperm-borne microRNAs (miRNAs) are involved in mammalian preimplantation embryonic development. In humans, spermatozoan miR-34c levels are correlated with in vitro fertilization outcomes, such as embryo quality and the clinical pregnancy and live birth rates. In rabbits and cows, miR-34c improves the developmental competence of embryos generated by somatic cell nuclear transfer. However, the mechanisms underlying the regulation of embryonic development by miR-34c remain unknown.

METHODS

Female C57BL/6 mice (6-8 weeks old) were superovulated, and pronucleated zygotes were collected and microinjected with an miR-34c inhibitor or a negative-control RNA. The embryonic development of the microinjected zygotes was evaluated, and the messenger RNA (mRNA) expression profiles of the embryos at the two-cell, four-cell and blastocyst stages (five embryos per group) were determined by RNA sequencing analysis. Gene expression levels were verified by reverse transcription-quantitative polymerase chain reaction. Cluster analysis and heat map visualization were performed to detect differentially expressed mRNAs. Pathway and process enrichment analyses were performed using ontology resources. Differentially expressed mRNAs were systematically analyzed using the Search Tool for the Retrieval of Interacting Genes/Proteins database to determine their biological functions.

RESULTS

Embryonic developmental potential was significantly reduced in zygotes microinjected with the miR-34c inhibitor compared with those microinjected with a negative-control RNA. Two-cell stage embryos microinjected with an miR-34c inhibitor presented altered transcriptomic profiles, with upregulated expression of maternal miR-34c target mRNAs and classical maternal mRNAs. Differentially expressed transcripts were mainly of genes associated with lipid metabolism and cellular membrane function at the two-cell stage, with cell-cycle phase transition and energy metabolism at the four-cell stage; and with vesicle organization, lipid biosynthetic process and endomembrane system organization at the blastocyst stage. We also showed that genes related to preimplantation embryonic development, including Alkbh4, Sp1, Mapk14, Sin3a, Sdc1 and Laptm4b, were significantly downregulated after microinjection of an miR-34c inhibitor.

CONCLUSIONS

Sperm-borne miR-34c may regulate preimplantation embryonic development by affecting multiple biological processes, such as maternal mRNA degradation, cellular metabolism, cell proliferation and blastocyst implantation. Our data demonstrate the importance of sperm-derived miRNAs in the development of preimplantation embryos.

The biological functions of maternal-derived extracellular vesicles during pregnancy and lactation and its impact on offspring health

During pregnancy and lactation, mothers provide not only nutrients, but also many bioactive components for their offspring through placenta and breast milk, which are essential for offspring development. Extracellular vesicles (EVs) are nanovesicles containing a variety of biologically active molecules and participate in the intercellular communication. In the past decade, an increasing number of studies have reported that maternal-derived EVs play a crucial role in offspring growth, development, and immune system establishment. Hereby, we summarized the characteristics of EVs; biological functions of maternal-derived EVs during pregnancy, including implantation, decidualization, placentation, embryo development and birth of offspring; biological function of breast milk-derived EVs (BMEs) on infant oral and intestinal diseases, immune system, neurodevelopment, and metabolism. In summary, emerging studies have revealed that maternal-derived EVs play a pivotal role in offspring health. As such, maternal-derived EVs may be used as promising biomarkers in offspring disease diagnosis and treatment. However, existing research on maternal-derived EVs and offspring health is largely limited to animal and cellular studies. Evidence from human studies is needed.

Extracellular vesicles are dynamic regulators of maternal glucose homeostasis during pregnancy

Homeostatic regulation of the maternal milieu during pregnancy is critical for maternal and fetal health. The placenta facilitates critical communication between maternal and fetal compartments, in part, through the production of extracellular vesicles (EVs). EVs enable tissue synchrony via cell-cell and long-distance communication and are at their highest circulating concentration during pregnancy. While much work has been done investigating how physiological challenges in pregnancy affect the fetus, the role of placental communication in maternal health has not been well examined. We previously identified placental O-glycosyl transferase (OGT), a glucose-sensing enzyme, as a target of maternal stress where OGT levels and activity affected the O-glycosylation of proteins critical for EV cargo loading and secretion. Here, we hypothesized that placental OGT plays an essential role in maternal homeostatic regulation during pregnancy via its regulation of maternal circulating EV concentrations. Our studies found that changes to key metabolic factors over the circadian cycle, including glucocorticoids, insulin, and glucose, were significantly associated with changes in circulating EV concentration. Targeting placental OGT in mice, we found a novel significant positive relationship between placental OGT and maternal circulating EV concentration that was associated with improving maternal glucose tolerance during pregnancy. Finally, an intravenous elevation in EVs, matching the concentration of EVs during pregnancy, shifted non-pregnant female glucose sensitivity, blunted glucose variance, and improved synchrony of glucose uptake. These data suggest an important and novel role for circulating EVs as homeostatic regulators important in maternal health during pregnancy.

Exosomes: The role in mammalian reproductive regulation and pregnancy-related diseases

Exosomes are a kind of extracellular vesicles that are produced and secreted by different mammalian cells. They serve as cargo proteins and can transfer different kinds of biomolecules, including proteins, lipids, and nucleic acids, which consequently act on target cells to exert different biological effects. Recent years have witnessed a significant increase in the number of studies on exosomes due to the potential effects of exosomes in the diagnosis and treatment of cancers, neurodegenerative diseases, and immune disorders. Previous studies have demonstrated that exosomal contents, especially miRNAs, are implicated in numerous physiological processes such as reproduction, and are crucial regulators of mammalian reproduction and pregnancy-related diseases. Here, we describe the origin, composition, and intercellular communication of exosomes, and discuss their functions in follicular development, early embryonic development, embryonic implantation, male reproduction and development of pregnancy-related diseases in humans and animals. We believe this study will provide a foundation for revealing the mechanism of exosomes in regulating mammalian reproduction, and providing new approaches and ideas for the diagnosis and treatment of pregnancy-related diseases.

Uterine luminal-derived extracellular vesicles: potential nanomaterials to improve embryo implantation

Most pregnancy losses worldwide are caused by implantation failure for which there is a lack of effective therapeutics. Extracellular vesicles are considered potential endogenous nanomedicines because of their unique biological functions. However, the limited supply of ULF-EVs prevents their development and application in infertility diseases such as implantation failure. In this study, pigs were used as a human biomedical model, and ULF-EVs were isolated from the uterine luminal. We comprehensively characterized the proteins enriched in ULF-EVs and revealed their biological functions in promoting embryo implantation. By exogenously supplying ULF-EVs, we demonstrated that ULF-EVs improve embryo implantation, suggesting that ULF-EVs are a potential nanomaterial to treat implantation failure. Furthermore, we identified that MEP1B is important in improving embryo implantation by promoting trophoblast cell proliferation and migration. These results indicated that ULF-EVs can be a potential nanomaterial to improve embryo implantation.

Bacterial extracellular vesicles in the microbiome of first-pass meconium in newborn infants

BACKGROUND

Bacterial extracellular vesicles (EVs) are more likely to cross biological barriers than whole-cell bacteria. We previously observed EV-sized particles by electron microscopy in the first-pass meconium of newborn infants. We hypothesized that EVs may be of bacterial origin and represent a novel entity in the human microbiome during fetal and perinatal periods.

METHODS

We extracted EVs from first-pass meconium samples of 17 newborn infants and performed bacterial 16S rRNA gene sequencing of the vesicles. We compared the EV content from the meconium samples of infants based on the delivery mode, and in vaginal delivery samples, based on the usage of intrapartum antibiotics.

RESULTS

We found bacterial EVs in all first-pass meconium samples. All EV samples had bacterial RNA. Most of the phyla present in the samples were Firmicutes (62%), Actinobacteriota (18%), Proteobacteria (10%), and Bacteroidota (7.3%). The most abundant genera were Streptococcus (21%) and Staphylococcus (17%). The differences between the delivery mode and exposure to antibiotics were not statistically significant.

CONCLUSIONS

Bacterial EVs were present in the first-pass meconium of newborn infants. Bacterial EVs may represent an important novel feature of the gut microbiome during fetal and perinatal periods.

IMPACT

We show that bacterial extracellular vesicles are present in the microbiome of first-pass meconium in newborn infants. This is a novel finding. To our knowledge, this is the first study to report the presence of bacterial extracellular vesicles in the gut microbiome during fetal and perinatal periods. This finding is important because bacterial extracellular vesicles are more likely to cross biological barriers than whole-cell bacteria. Thus, the early gut microbiome may potentially interact with the host through bacterial EVs.

The Proteome of Large or Small Extracellular Vesicles in Pig Seminal Plasma Differs, Defining Sources and Biological Functions

Seminal plasma contains many morphologically heterogeneous extracellular vesicles (sEVs). These are sequentially released by cells of the testis, epididymis, and accessory sex glands and involved in male and female reproductive processes. This study aimed to define in depth sEV subsets isolated by ultrafiltration and size exclusion chromatography, decode their proteomic profiles using liquid chromatography-tandem mass spectrometry, and quantify identified proteins using sequential window acquisition of all theoretical mass spectra. The sEV subsets were defined as large (L-EVs) or small (S-EVs) by their protein concentration, morphology, size distribution, and EV-specific protein markers and purity. Liquid chromatography-tandem mass spectrometry identified a total of 1034 proteins, 737 of them quantified by SWATH in S-EVs, L-EVs, and non-EVs-enriched samples (18-20 size exclusion chromatography-eluted fractions). The differential expression analysis revealed 197 differentially abundant proteins between both EV subsets, S-EVs and L-EVs, and 37 and 199 between S-EVs and L-EVs versus non-EVs-enriched samples, respectively. The gene ontology enrichment analysis of differentially abundant proteins suggested, based on the type of protein detected, that S-EVs could be mainly released through an apocrine blebbing pathway and be involved in modulating the immune environment of the female reproductive tract as well as during sperm-oocyte interaction. In contrast, L-EVs could be released by fusion of multivesicular bodies with the plasma membrane becoming involved in sperm physiological processes, such as capacitation and avoidance of oxidative stress. In conclusion, this study provides a procedure capable of isolating subsets of EVs from pig seminal plasma with a high degree of purity and shows differences in the proteomic profile between EV subsets, indicating different sources and biological functions for the sEVs.

Immune alterations in recurrent implantation failure

A failure to achieve pregnancy after three or more embryo transfer cycles with high-quality blastocysts is referred to as recurrent implantation failure (RIF). RIF can be due to altered uterine factors or male factors or embryo factors. Disrupted endometrial receptivity, altered expression of genes in several pathways, immunologic disturbances in the peripheral blood and/or the endometrium, and epigenetic alterations are associated with RIF. Amongst the immunologic disturbances, altered Th1/Th2 ratio, altered NK cell and macrophage numbers are observed in women with RIF. However, not all women with RIF have the same kind of immune dysfunction suggesting that RIF is a heterogeneous condition associated with varied immune responses and one size may not fit all. Thus, personalized therapies based on the immune status of the patient are being tested in women with RIF. In general, women with a high Th1/Th2 ratio are offered Tacrolimus, while intravenous IgG is recommended in women with high NK cell numbers/HLA mismatch. Women with hyperactivated immune status in the uterus are offered progesterone support, prednisolone, vitamin E, and intralipid treatment to suppress inflammation and oxidative stress, while endometrial scratching and intrauterine hCG administration are offered to women with hypo-active immune status. There is a need for standardized tests for evaluation of immune status in patients and sufficiently powered randomized controlled trials for personalized therapies to determine which of these will be beneficial in women with RIF. Till then, the ART community should limit the use of such add-on interventions in women with RIF.

miRNA profiling in intrauterine exosomes of pregnant cattle on day 7

Intrauterine exosomes have been identified to be involved in the embryo development and implantation. The aim of this study was to explore the role of miRNAs in intrauterine exosomes in bovine pregnancy. Intrauterine exosomes were collected from uterine flushing fluids of three donor and three recipient Xianan cows 7 days after fertilization. Intrauterine exosomes miRNAs were extracted and the exosomal miRNAs expression levels were analyzed. Sixty miRNAs differed significantly in their amounts between donors and recipients (p-value < 0.05, |log2(FoldChange)| > 1). Twenty-two miRNAs were upregulated and 38 downregulated in the group of donor cows. The bta-miR-184 was the most significant (P _{Benjamini-Hochberg} < 0.001). A total of 9,775 target genes were predicted using the 60 miRNAs. GO and KEGG analysis showed that the target genes were enriched in several biological processes or pathways associated with embryo implantation and endometrial development, such as cell adhesion, cell junction, focal adhesion, and Rap1 signaling pathway. Our findings suggest that, in cattle early pregnancy stage, these differently expressed miRNAs in intrauterine exosomes involved in embryo implantation and endometrial development, which may exert a significant effect and influence the uterine microenvironment for embryo implantation. These results could provide reference for screening and exploring the intrauterine exosomal miRNA affecting embryo implantation.

Immune Tolerance of Embryo Implantation and Pregnancy: The Role of Human Decidual Stromal Cell- and Embryonic-Derived Extracellular Vesicles

Embryo–endometrial communication plays a critical role in embryo implantation and the establishment of a successful pregnancy. Successful pregnancy outcomes involve maternal immune modulation during embryo implantation. The endometrium is usually primed and immunomodulated by steroid hormones and embryo signals for subsequent embryo implantation and the maintenance of pregnancy. The roles of extracellular vesicles (EVs) and microRNAs for the embryo–maternal interactions have been elucidated recently. New evidence shows that endometrial EVs and trophectoderm-originated EV cargo, including microRNAs, proteins, and lipids in the physiological microenvironment, regulate maternal immunomodulation for embryo implantation and subsequent pregnancy. On the other hand, trophoblast-derived EVs also control the cross-communication between the trophoblasts and immune cells. The exploration of EV functions and mechanisms in the processes of embryo implantation and pregnancy will shed light on a practical tool for the diagnostic or therapeutic approaches to reproductive medicine and infertility.

Extracellular vesicles derived from endometrial epithelial cells deliver exogenous miR-92b-3p to affect the function of embryonic trophoblast cells via targeting TSC1 and DKK3

BACKGROUND

Extracellular vesicles (EVs) could mediate embryo-maternal communication to affect embryo implantation by delivering biology information, including microRNA (miRNA), protein, lipid. Our previous research shows that miR-92b-3p was differentially expressed in EVs of uterine flushing fluids during the embryo implantation period. However, the role of miR-92b-3p from EVs in embryo implantation remains elusive.

MATERIALS AND METHODS

EVs were isolated from porcine endometrial epithelial cells (EECs) by ultracentrifugation. MiR-92b-3p mimics and EVs were used to regulate the expression of miR-92b-3p in porcine trophoblast cells (PTr2 cells). Cell proliferation, migration and adhesion analyses were used to observe the phenotype. RT-qPCR, western blot and dual-luciferase reporter assay were used to assess the targets of miR-92b-3p.

RESULTS

In this study, EVs derived from porcine EECs were identified and could be taken up by PTr2 cells. We found that the EVs derived from EECs transfected with miR-92b-3p mimic (EVs-miR-92b-3p) significantly promoted the proliferation, migration and adhesion of PTr2 cells. We verified that Tuberous sclerosis complex subunit (TSC1) and Dickkopf 3 (DKK3) were the target genes of miR-92b-3p. Moreover, our study showed that miR-92b-3p plays a vital role in PTr2 cells via targeting TSC1 and DKK3. Furthermore, the 3'UTR vectors of TSC1 and DKK3 can rescue the effect of miR-92b-3p on PTr2 cells.

CONCLUSIONS

Taken together, this study reveals a novel mechanism that EVs derived from porcine EECs treated with miR-92b-3p crosstalk with trophoblasts by targeting TSC1 and DKK3, leading to an enhanced ability for implantation.

miR‑519d‑3p released by human blastocysts negatively regulates endometrial epithelial cell adhesion by targeting HIF1α

Successful embryo implantation requires a competent embryo, a receptive endometrium and synchronized communication between them. The selection of embryos with the highest implantation potential remains a challenge in the field of assisted reproductive technology. Moreover, little is known about the precise molecular mechanisms underlying embryo‑endometrium crosstalk. MicroRNAs (miRNAs/miRs) have been detected in the spent embryo culture medium (SCM); however, their functions at the preimplantation stage remain unclear. In the present study, human SCM samples were collected during in vitro fertilization/intracytoplasmic sperm injection‑embryo transfer and divided into implanted and not‑implanted groups according to the clinical pregnancy outcomes. Total RNA was extracted and six miRNAs (miR‑372‑3p, miR‑373‑3p, miR‑516b‑5p, miR‑517a‑3p, miR‑519d‑3p and miR‑520a‑3p) were selected for reverse transcription‑quantitative PCR (RT‑qPCR) analysis. The results revealed that miR‑372‑3p and miR‑519d‑3p were markedly increased in SCM from blastocysts that failed to implant compared with in blastocysts that implanted. The receiver operating characteristic curve analysis revealed that miR‑519d‑3p was superior to miR‑372‑3p in predicting pregnancy outcomes. In vitro miRNA uptake and cell adhesion assays were performed to determine whether miR‑519d‑3p could be taken up by endometrial epithelial cells and to examine the biological roles of miR‑519d‑3p after internalization. Potential targets of miR‑519d‑3p were verified using a dual‑luciferase reporter system. The results demonstrated that miR‑519d‑3p was taken up by human endometrial epithelial cells and that it may inhibit embryo adhesion by targeting HIF1α. Using RT‑qPCR, western blot analysis and flow cytometry assay, HIF1α was shown to inhibit the biosynthesis of fucosyltransferase 7 and sialyl‑Lewis X (sLe^x), a cell‑surface oligosaccharide that serves an important role in embryonic apposition and adhesion. In addition, a mouse model was established and the results suggested that miR‑519d‑3p overexpression hampered embryo implantation in vivo. Taken together, miRNAs in SCM may serve as novel biomarkers for embryo quality. Furthermore, miR‑519d‑3p was shown to mediate embryo‑endometrium crosstalk and to negatively regulate embryo implantation by targeting HIF1α/FUT7/sLe^x pathway.

microRNA-based signatures obtained from endometrial fluid identify implantative endometrium

STUDY QUESTION

Is it possible to use free and extracellular vesicle-associated microRNAs (miRNAs) from human endometrial fluid (EF) samples as non-invasive biomarkers for implantative endometrium?

SUMMARY ANSWER

The free and extracellular vesicle-associated miRNAs can be used to detect implantative endometrium in a non-invasive manner.

WHAT IS KNOWN ALREADY

miRNAs and extracellular vesicles (EVs) from EF have been described as mediators of the embryo–endometrium crosstalk. Therefore, the analysis of miRNA from this fluid could become a non-invasive technique for recognizing implantative endometrium. This analysis could potentially help improve the implantation rates in ART.

STUDY DESIGN, SIZE, DURATION

In this prospective study, we first optimized different protocols for EVs and miRNA analyses using the EF of a setup cohort (n = 72). Then, we examined differentially expressed miRNAs in the EF of women with successful embryo implantation (discovery cohort n = 15/validation cohort n = 30) in comparison with those for whom the implantation had failed (discovery cohort n = 15/validation cohort n = 30). Successful embryo implantation was considered when pregnancy was confirmed by vaginal ultrasound showing a gestational sac 4 weeks after embryo transfer (ET).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The EF of the setup cohort was obtained before starting fertility treatment during the natural cycle, 16–21 days after the beginning of menstruation. For the discovery and validation cohorts, the EF was collected from women undergoing frozen ET on Day 5, and the samples were collected immediately before ET. In this study, we compared five different methods; two of them based on direct extraction of RNA and the other three with an EV enrichment step before the RNA extraction. Small RNA sequencing was performed to determine the most efficient method and find a predictive model differentiating between implantative and non-implantative endometrium. The models were confirmed using quantitative PCR in two sets of samples (discovery and validation cohorts) with different implantation outcomes.

MAIN RESULTS AND THE ROLE OF CHANCE

The protocols using EV enrichment detected more miRNAs than the methods based on direct RNA extraction. The two most efficient protocols (using polymer-based precipitation (PBP): PBP-M and PBP-N) were used to obtain two predictive models (based on three miRNAs) allowing us to distinguish between an implantative and non-implantative endometrium. The first Model 1 (PBP-M) (discovery: AUC = 0.93; P-value = 0.003; validation: AUC = 0.69; P-value = 0.019) used hsa-miR-200b-3p, hsa-miR-24-3p and hsa-miR-148b-3p. Model 2 (PBP-N) (discovery: AUC = 0.92; P-value = 0.0002; validation: AUC = 0.78; P-value = 0.0002) used hsa-miR-200b-3p, hsa-miR-24-3p and hsa-miR-99b-5p. Functional analysis of these miRNAs showed strong association with key implantation processes such as in utero embryonic development or transforming growth factor-beta signaling.

LARGE SCALE DATA

The FASTQ data are available in the GEO database (access number GSE178917).

LIMITATIONS, REASONS FOR CAUTION

One important factor to consider is the inherent variability among the women involved in the trial and among the transferred embryos. The embryos were pre-selected based on morphology, but neither genetic nor molecular studies were conducted, which would have improved the accuracy of our tests. In addition, a limitation in miRNA library construction is the low amount of input RNA.

WIDER IMPLICATIONS OF THE FINDINGS

We describe new non-invasive protocols to analyze miRNAs from small volumes of EF. These protocols could be implemented in clinical practice to assess the status of the endometrium before attempting ET. Such evaluation could help to avoid the loss of embryos transferred to a non-implantative endometrium.

STUDY FUNDING/COMPETING INTEREST(S)

J.I.-P. was supported by a predoctoral grant from the Basque Government (PRE_2017_0204). This study was partially funded by the Grant for Fertility Innovation (GFI, 2011) from Merck (Darmstadt, Germany). It was also supported by the Spanish Ministry of Economy and Competitiveness MINECO within the National Plan RTI2018-094969-B-I00, the European Union's Horizon 2020 research and innovation program (860303), the Severo Ochoa Centre of Excellence Innovative Research Grant (SEV-2016-0644) and the Instituto de Salud Carlos III (PI20/01131). The funding entities did not play any role in the study design, collection, analysis and interpretation of data, writing of the report or the decision to submit the article for publication. The authors declare no competing interests.

Mechanisms of group B Streptococcus-mediated preterm birth: lessons learnt from animal models

Group B Streptococcus (GBS) is an opportunistic pathogenic bacterium which upon colonization in the female reproductive tract can cause preterm births, fetal injury, and demise. Several determinants for GBS pathogenesis have been explored so far through the studies using animal models ranging from mice to non-human primates. The results from these experimental data have identified outer membrane vesicles, β-hemolysin, hyaluronidase, and Cas9 of GBS as major virulence factors leading to preterm births. Most of these factors drive inflammation through activation of NLRP3 and elevated production of IL1-β. However, the absence of one of the factors from the pathogen reduces but does not completely abolish the pathogenesis of GBS suggesting the involvement of more than one factor in causing preterm birth. This makes further exploration of other virulence factors of GBS pathogenesis important in gaining an insight into the mechanistic basis of GBS-mediated preterm births.

Lay summary

Group B Streptococcus (GBS) is a pathogenic bacteria whose infection in the reproductive tract during pregnancy can cause premature delivery. This bacterial infection is one of the major causes of death of mother and baby during pregnancy, and the bacteria is prevalent in all parts of the world. This makes the research on GBS so important and many of the mechanisms behind GBS infection during pregnancy still remain unexplored. In this review, we have outlined how various animal models contributed in finding the mechanism of GBS pathogenesis. The review also focuses on compiling various virulence factors which makes GBS pathogenic in the vulnerable. Understanding the mechanisms of infection by GBS will be crucial in developing drugs and vaccines to protect against the harmful effects of the bacteria.

Leveraging bioengineering to assess cellular functions and communication within human fetal membranes

The fetal membranes enclose the growing fetus and amniotic fluid. Preterm prelabor rupture of fetal membranes is a leading cause of preterm birth. Fetal membranes are composed of many different cell types, both structural and immune. These cells must coordinate functions for tensile strength and membrane integrity to contain the growing fetus and amniotic fluid. They must also balance immune responses to pathogens with maintaining maternal-fetal tolerance. Perturbation of this equilibrium can lead to preterm premature rupture of membranes without labor. In this review, we describe the formation of the fetal membranes to orient the reader, discuss some of the common forms of communication between the cell types of the fetal membranes, and delve into the methods used to tease apart this paracrine signaling within the membranes, including emerging technologies such as organ-on-chip models of membrane immunobiology.

The role of extracellular vesicles in animal reproduction and diseases

Extracellular vesicles (EVs) are nanosized membrane-enclosed compartments that serve as messengers in cell-to-cell communication, both in normal physiology and in pathological conditions. EVs can transfer functional proteins and genetic information to alter the phenotype and function of recipient cells, which undergo different changes that positively affect their structural and functional integrity. Biological fluids are enriched with several subpopulations of EVs, including exosomes, microvesicles (MVs), and apoptotic bodies carrying several cargoes, such as lipids, proteins, and nucleic acids. EVs associated with the reproductive system are actively involved in the regulation of different physiological events, including gamete maturation, fertilization, and embryo and fetal development. EVs can influence follicle development, oocyte maturation, embryo production, and endometrial-conceptus communication. EVs loaded with cargoes are used to diagnose various diseases, including pregnancy disorders; however, these are dependent on the type of cell of origin and pathological characteristics. EV-derived microRNAs (miRNAs) and proteins in the placenta regulate inflammatory responses and trophoblast invasion through intercellular delivery in the placental microenvironment. This review presents evidence regarding the types of extracellular vesicles, and general aspects of isolation, purification, and characterization of EVs, particularly from various types of embryos. Further, we discuss EVs as mediators and messengers in reproductive biology, the effects of EVs on placentation and pregnancy disorders, the role of EVs in animal reproduction, in the male reproductive system, and mother and embryo cross-communication. In addition, we emphasize the role of microRNAs in embryo implantation and the role of EVs in reproductive and therapeutic medicine. Finally, we discuss the future perspectives of EVs in reproductive biology.

miR-196a-5p-Rich Extracellular Vesicles from Trophoblasts Induce M1 Polarization of Macrophages in Recurrent Miscarriage

Purpose

Numerous studies have described the presence of crosstalk between trophoblasts and macrophages and the critical role it plays in recurrent miscarriage (RM). However, the mechanism of trophoblast-derived extracellular vesicle (EV) miRNAs and their interactions with decidual macrophages in the pathogenesis of RM remains unclear.

Materials and Methods

miRNA-seq was used to identify the differentially expressed miRNAs between RM patients and healthy controls. qPCR and in situ hybridization assays were performed to analyze the expression levels of miR-196a-5p in RM. THP-1 cells were treated with EVs, and qPCR and flow cytometry were performed to explore the polarization of macrophages. To explore the crosstalk between trophoblasts and macrophages, a coculture model and a series of cell function assays were performed.

Results

We first demonstrated that miR-196a-5p expression was higher in the cytotrophoblasts of villous tissues and plasma EVs from RM patients. miR-196a-5p derived from trophoblasts could be transferred into macrophages via EVs to induce M1 polarization via IκBα-mediated NF-κB pathway. Moreover, we found that M1 macrophages induced by EV miR-196a-5p derived from trophoblasts conversely regulated the proliferation, migration, and apoptosis of trophoblasts via TNF-α.

Conclusions

This study indicated that trophoblast-derived EV miR-196a-5p was positively associated with RM and functioned by regulating the crosstalk between trophoblasts and macrophages. These findings may attribute to identify a novel biomarker specific for RM.

Transcriptome regulation of extracellular vesicles derived from porcine uterine flushing fluids during peri-implantation on endometrial epithelial cells and embryonic trophoblast cells

The extracellular vesicles (EVs) in uterine fluids play a vital role in embryo implantation by mediating intrauterine communication between conceptus and maternal endometrium in pigs. However, the regulatory mechanism of EVs in uterine fluids is largely unclear. In order to understand the effect of EVs in uterine flushing fluids (UFs) during embryo implantation on endometrial epithelial cells (EECs) and embryonic trophoblast cells (PTr2 cells). The UFs-EVs on day 13 of pregnancy (D13) were added to the culture medium of EECs and PTr2 cells. It was found that PKH-67 labeled UFs-EVs could be taken up in EECs and PTr2 cells. Transcriptome sequencing analysis showed that a total of 1793 and 6279 genes were differentially expressed in the EECs and PTr2 cells after the treatment of UFs-EVs on D13, respectively. Among these genes, real-time quantitative PCR (RT-qPCR) results indicated that ID2, ITGA5, CXCL10 and CXCL11 genes were differentially expressed in both EECs and PTr2 cells after treatment. Bioinformatics analysis showed that the differentially expressed (DE) genes in EECs and PTr2 cells after treatment are involved in immune regulation, cell migration, cell adhesion and the secretion and uptake of EVs. Our research offers novel insight into the regulation mechanism of UFs-EVs on D13 in EECs and PTr2 cells.

Immunological Changes in Pregnancy and Prospects of Therapeutic Pla-Xosomes in Adverse Pregnancy Outcomes

Stringent balance of the immune system is a key regulatory factor in defining successful implantation, fetal development, and timely parturition. Interference in these primary regulatory mechanisms, either at adolescence or prenatal state led to adverse pregnancy outcomes. Fertility restoration with the help of injectable gonadotrophins/progesterone, ovulation-inducing drugs, immunomodulatory drugs (corticosteroids), and reproductive surgeries provides inadequate responses, which manifest its own side effects. The development of a potential diagnostic biomarker and an effectual treatment for adverse pregnancy outcomes is a prerequisite to maternal and child health. Parent cell originated bi-layered-intraluminal nano-vesicles (30-150 nm) also known as exosomes are detected in all types of bodily fluids like blood, saliva, breast milk, urine, etc. Exosomes being the most biological residual structures with the least cytotoxicity are loaded with cargo in the form of RNAs (miRNAs), proteins (cytokines), hormones (estrogen, progesterone, etc.), cDNAs, and metabolites making them chief molecules of cell-cell communication. Their keen involvement in the regulation of biological processes has portrayed them as the power shots of cues to understand the disease's pathophysiology and progression. Recent studies have demonstrated the role of immunexosomes (immunomodulating exosomes) in maintaining unwavering immune homeostasis between the mother and developing fetus for a healthy pregnancy. Moreover, the concentration and size of the exosomes are extensively studied in adverse pregnancies like preeclampsia, gestational diabetes mellitus (GDM), and preterm premature rupture of membrane (pPROMs) as an early diagnostic marker, thus giving in-depth information about their pathophysiology. Exosomes have also been engineered physically as well as genetically to enhance their encapsulation efficiency and specificity in therapy for cancer and adverse pregnancies. Successful bench to bedside discoveries and interventions in cancer has motivated developmental biologists to investigate the role of immunexosomes and their active components. Our review summarizes the pre-clinical studies for the use of these power-shots as therapeutic agents. We envisage that these studies will pave the path for the use of immunexosomes in clinical settings for reproductive problems that arise due to immune perturbance in homeostasis either at adolescence or prenatal state.

Epigenetics of pregnancy: looking beyond the DNA code

Epigenetics is the branch of genetics that studies the different mechanisms that influence gene expression without direct modification of the DNA sequence. An ever-increasing amount of evidence suggests that such regulatory processes may play a pivotal role both in the initiation of pregnancy and in the later processes of embryonic and fetal development, thus determining long-term effects even in adult life. In this narrative review, we summarize the current knowledge on the role of epigenetics in pregnancy, from its most studied and well-known mechanisms to the new frontiers of epigenetic regulation, such as the role of ncRNAs and the effects of the gestational environment on fetal brain development. Epigenetic mechanisms in pregnancy are a dynamic phenomenon that responds both to maternal-fetal and environmental factors, which can influence and modify the embryo-fetal development during the various gestational phases. Therefore, we also recapitulate the effects of the most notable environmental factors that can affect pregnancy and prenatal development, such as maternal nutrition, stress hormones, microbiome, and teratogens, focusing on their ability to cause epigenetic modifications in the gestational environment and ultimately in the fetus. Despite the promising advancements in the knowledge of epigenetics in pregnancy, more experience and data on this topic are still needed. A better understanding of epigenetic regulation in pregnancy could in fact prove valuable towards a better management of both physiological pregnancies and assisted reproduction treatments, other than allowing to better comprehend the origin of multifactorial pathological conditions such as neurodevelopmental disorders.

Extracellular vesicles and immune response during pregnancy: A balancing act

The mechanisms underlying maternal tolerance of the semi- or fully-allogeneic fetus are intensely investigated. Across gestation, feto-placental antigens interact with the maternal immune system locally within the trophoblast-decidual interface and distantly through shed cells and soluble molecules that interact with maternal secondary lymphoid tissues. The discovery of extracellular vesicles (EVs) as local or systemic carriers of antigens and immune-regulatory molecules has added a new dimension to our understanding of immune modulation prior to implantation, during trophoblast invasion, and throughout the course of pregnancy. New data on immune-regulatory molecules, located on EVs or within their cargo, suggest a role for EVs in negotiating immune tolerance during gestation. Lessons from the field of transplant immunology also shed light on possible interactions between feto-placentally derived EVs and maternal lymphoid tissues. These insights illuminate a potential role for EVs in major obstetrical disorders. This review provides updated information on intensely studied, pregnancy-related EVs, their cargo molecules, and patterns of fetal-placental-maternal trafficking, highlighting potential immune pathways that might underlie immune suppression or activation in gestational health and disease. Our summary also underscores the likely need to broaden the definition of the maternal-fetal interface to systemic maternal immune tissues that might interact with circulating EVs.

The Molecular Mechanisms Through Which Placental Mesenchymal Stem Cell-Derived Extracellular Vesicles Promote Myelin Regeneration

Multiple sclerosis (MS) is a debilitating degenerative disease characterized by an immunological attack on the myelin sheath leading to demyelination and axon degeneration. Mesenchymal stem/stromal cells (MSCs) and secreted extracellular vesicles (EVs) have become attractive targets as therapies to treat neurodegenerative diseases such as MS due to their potent immunomodulatory and regenerative properties. The placenta is a unique source of MSCs (PMSCs), demonstrates "fetomaternal" tolerance during pregnancy, and serves as a novel source of MSCs for the treatment of neurodegenerative diseases. PMSCs and PMSC-EVs have been shown to promote remyelination in animal models of MS, however, the molecular mechanisms by which modulation of autoimmunity and promotion of myelination occurs have not been well elucidated. The current review will address the molecular mechanisms by which PMSC-EVs can promote remyelination in MS.

Porcine uterine luminal fluid-derived extracellular vesicles improve conceptus-endometrial interaction during implantation

Successful implantation of porcine conceptus requires synergistic interaction with various signal molecules in the maternal uterus. Extracellular vesicles (EVs) in uterine luminal fluid (ULF) of mice play important roles in conceptus development. However, studies have not explored the roles of extracellular vesicles (EV) in ULF of pigs. The aim of this study was to identify characteristics, origin, and roles of ULF-derived EVs on day 9 of the estrous cycle and on day 9,12 and 15 of pregnancy in pigs. Western blot, BCA assay and HE staining analysis showed increase in EVs concentration in ULF began from day 12 of pregnancy. Immunofluorescence staining and transmission electron microscopy analysis showed that EVs were mainly derived from endometrial epithelial cells. Fluorescent labeling, CCK-8 and transwell migration assays showed that these EVs were delivered to the trophoblast or parthenogenetic activation embryos to regulate proliferation and migration of trophoblast cells. A total of 305 miRNAs were identified using small RNA sequencing analysis. Functional enrichment analysis showed that miRNAs in these EVs potentially play vital regulatory functions in EV transportation or conceptus implantation. QRT-PCR analysis was used to further verify the RNA-seq data. The findings of this study provide information on the functions of porcine ULF-derived EVs and provide a reference dataset for future translational studies on porcine ULF-derived EVs.

DNA damage in preimplantation embryos and gametes: specification, clinical relevance and repair strategies

BACKGROUND

DNA damage is a hazard that affects all cells of the body. DNA-damage repair (DDR) mechanisms are in place to repair damage and restore cellular function, as are other damage-induced processes such as apoptosis, autophagy and senescence. The resilience of germ cells and embryos in response to DNA damage is less well studied compared with other cell types. Given that recent studies have described links between embryonic handling techniques and an increased likelihood of disease in post-natal life, an update is needed to summarize the sources of DNA damage in embryos and their capacity to repair it. In addition, numerous recent publications have detailed novel techniques for detecting and repairing DNA damage in embryos. This information is of interest to medical or scientific personnel who wish to obtain undamaged embryos for use in offspring generation by ART.

OBJECTIVE AND RATIONALE

This review aims to thoroughly discuss sources of DNA damage in male and female gametes and preimplantation embryos. Special consideration is given to current knowledge and limits in DNA damage detection and screening strategies. Finally, obstacles and future perspectives in clinical diagnosis and treatment (repair) of DNA damaged embryos are discussed.

SEARCH METHODS

Using PubMed and Google Scholar until May 2021, a comprehensive search for peer-reviewed original English-language articles was carried out using keywords relevant to the topic with no limits placed on time. Keywords included ‘DNA damage repair’, ‘gametes’, ‘sperm’, ‘oocyte’, ‘zygote’, ‘blastocyst’ and ‘embryo’. References from retrieved articles were also used to obtain additional articles. Literature on the sources and consequences of DNA damage on germ cells and embryos was also searched. Additional papers cited by primary references were included. Results from our own studies were included where relevant.

OUTCOMES

DNA damage in gametes and embryos can differ greatly based on the source and severity. This damage affects the development of the embryo and can lead to long-term health effects on offspring. DDR mechanisms can repair damage to a certain extent, but the factors that play a role in this process are numerous and altogether not well characterized. In this review, we describe the multifactorial origin of DNA damage in male and female gametes and in the embryo, and suggest screening strategies for the selection of healthy gametes and embryos. Furthermore, possible therapeutic solutions to decrease the frequency of DNA damaged gametes and embryos and eventually to repair DNA and increase mitochondrial quality in embryos before their implantation is discussed.

WIDER IMPLICATIONS

Understanding DNA damage in gametes and embryos is essential for the improvement of techniques that could enhance embryo implantation and pregnancy success. While our knowledge about DNA damage factors and regulatory mechanisms in cells has advanced greatly, the number of feasible practical techniques to avoid or repair damaged embryos remains scarce. Our intention is therefore to focus on strategies to obtain embryos with as little DNA damage as possible, which will impact reproductive biology research with particular significance for reproductive clinicians and embryologists.

Proteomic analysis of extracellular vesicles secreted by primary human epithelial endometrial cells reveals key proteins related to embryo implantation

BACKGROUND

Successful implantation is dependent on coordination between maternal endometrium and embryo, and the role of EVs in the required cross-talk cell-to-cell has been recently established. In this regard, it has been reported that EVs secreted by the maternal endometrium can be internalized by human trophoblastic cells transferring their contents and enhancing their adhesive and invasive capacity. This is the first study to comprehensively evaluate three EV isolation methods on human endometrial epithelial cells in culture and to describe the proteomic content of EVs secreted by pHEECs from fertile women.

METHODS

Ishikawa cells and pHEECs were in vitro cultured and hormonally treated; subsequently, conditioned medium was collected and EVs isolated. Ishikawa cells were used for the comparison of EVs isolation methods ultracentrifugation, ExoQuick-TC and Norgen Cell Culture Media Exosome Purification Kit (n = 3 replicates/isolation method). pHEECs were isolated from endometrial biopsies (n = 8/replicate; 3 replicates) collected from healthy oocyte donors with confirmed fertility, and protein content of EVs isolated by the most efficient methodology was analysed using liquid chromatography-tandem mass spectrometry. EV concentration and size were analyzed by nanoparticle tracking analysis, EV morphology visualized by transmission electron microscopy and protein marker expression was determined by Western blotting.

RESULTS

Ultracentrifugation was the most efficient methodology for EV isolation from medium of endometrial epithelial cells. EVs secreted by pHEECs and isolated by ultracentrifugation were heterogeneous in size and expressed EV protein markers HSP70, TSG101, CD9, and CD81. Proteomic analysis identified 218 proteins contained in these EVs enriched in biological processes involved in embryo implantation, including cell adhesion, differentiation, communication, migration, extracellular matrix organization, vasculature development, and reproductive processes. From these proteins, 82 were selected based on their functional relevance in implantation success as possible implantation biomarkers.

CONCLUSIONS

EV protein cargos are implicated in biological processes related to endometrial receptivity, embryo implantation, and early embryo development, supporting the concept of a communication system between the embryo and the maternal endometrium via EVs. Identified proteins may define new biomarkers of endometrial receptivity and implantation success.

Investigation and Validation of Molecular Characteristics of Endometrium in Recurrent Miscarriage and Unexplained Infertility from a Transcriptomic Perspective

Recurrent miscarriage (RM) and unexplained infertility (UI) are gordian knots in reproductive medicine, which are troubling many patients, doctors, and researchers. Although these two diseases of early pregnancy have a significant impact on human reproductive health, little is known about the specific mechanisms, which caused treatment difficulties. This study focused on the molecular signatures underlying the pathological phenotypes of two diseases, with the hope of using statistical methods to identify the significant core genes. An unbiased Weighted Correlation Network Analysis (WGCNA) algorithm was used for endometrial transcriptome data analysis and the disease-related gene modules were screened out. Through enrichment analysis of the candidate genes, we found similarities between both diseases and shared enrichment of immune-related pathways. Therefore, we used immune algorithms to assess the infiltration of immune cells and found abnormal increases of CD8+T cells and neutrophils. In order to explore the molecular profile behind the immunophenotypic changes, we used the SVM algorithm and LASSO regression to identify the core genes with diagnostic capacity in both diseases and discussed their significance of immune disorders in the endometrium. In the end, the satisfactory diagnostic ability of these core genes was verified in the broader group. Our results demonstrated the presence of immune disorders in non-pregnancy tissues of RM and UI, and identified the core molecules of this phenotype, and discuss mechanisms. This provides exploratory evidence for the in-depth understanding of the mechanism of RM and UI and may provide potential targets for their future treatment.