An endometrial gene expression signature accurately predicts recurrent implantation failure after IVF

Hierarchical cluster analysis in the study of the effect of cytokine expression patterns on endometrial repair and receptivity after hysteroscopic adhesiolysis

Background

In a previous study, we reported that amnion promotes endometrial cell growth by regulating cytokines. In this study, hierarchical cluster analysis enabled the evaluation of cytokine expression changes after amnion treatment to be explored by cluster patterns. The role of IL1B on endometrial repair and receptivity was revealed.

Methods

A total of 30 patients were recruited in this clinical trial (NCT02496052) of hysteroscopic adhesiolysis. They were randomly allocated into an amnion grafts group (amnion group) and a control group. After hysteroscopic adhesiolysis, a Foley catheter covered with a sterilized freeze-dried amnion graft was inserted into the uterine cavity of the participants in the amnion group, whereas for the control group, a Foley catheter without amnion graft was inserted. After surgery, patient follow-up was done for a year. Uterine exudates were collected every day for seven days after surgery, and analyzed by enzyme-linked immunosorbent assays. Hierarchical cluster analysis was performed to compare expression patterns of each cytokine. Single-gene gene set enrichment analysis and differentially expressed genes enrichment analysis of IL1B were performed using NCBI GEO (N=151) to evaluate its potential mechanisms and impact on endometrial receptivity.

Results

Compared to the control group, cytokine expression patterns of the amnion group revealed significant stratifications, which were highly correlated with the expression levels of IL1B on the sixth to seventh day after surgery, improving the pregnant rate. Wilcoxon test revealed significantly low expression levels of IL1B in the reduced endometrial receptivity group compared to the normal group. Moreover, gene set enrichment analysis showed that lysosomes, cell cycle, and calcium signaling pathways were associated with the biological processes in which IL1B plays a role. Screening and enrichment analyses of differentially expressed genes further verified the mechanisms of action of IL1B on endometrial repair and receptivity recovery.

Conclusions

Amnion promotes endometrial repair and receptivity by altering the expression levels and patterns of IL1B. Furthermore, by affecting lysosomal, cell cycle, and calcium signaling pathways, IL1B may be one of the factors involved in endometrial repair and receptivity recovery.

The proliferative phase endometrium in IVF/ICSI: an in-cycle molecular analysis predictive of the outcome following fresh embryo transfer

STUDY QUESTION

Does an early proliferative phase endometrial biopsy harvested during ovarian stimulation harbour information predictive of the outcome following fresh embryo transfer (ET) in that same cycle?

SUMMARY ANSWER

Transcriptome analysis of the whole-tissue endometrium did not reveal significant differential gene expression (DGE) in relation to the outcome; however, the secretome profile of isolated, cultured and in vitro decidualized endometrial stromal cells (EnSCs) varied significantly between patients who had a live birth compared to those with an implantation failure following fresh ET in the same cycle as the biopsy.

WHAT IS KNOWN ALREADY

In the majority of endometrial receptivity research protocols, biopsies are harvested during the window of implantation (WOI). This, however, precludes ET in that same cycle, which is preferable as the endometrium has been shown to adapt over time. Endometrial biopsies taken during ovarian stimulation have been reported not to harm the chances of implantation, and in such biopsies DGE has been observed between women who achieve pregnancy versus those who do not. The impact of the endometrial proliferative phase on human embryo implantation remains unclear, but deserves further attention, especially since in luteal phase endometrial biopsies, a transcriptional signature predictive for repeated implantation failure has been associated with reduced cell proliferation, possibly indicating proliferative phase involvement. Isolation, culture and in vitro decidualization (IVD) of EnSCs is a frequently applied basic research technique to assess endometrial functioning, and a disordered EnSC secretome has previously been linked with failed implantation.

STUDY DESIGN, SIZE, DURATION

This study was nested in a randomized controlled trial (RCT) investigating the effect of endometrial scratching during the early follicular phase of ovarian stimulation on clinical pregnancy rates after IVF/ICSI. Of the 96 endometrial biopsies available, after eliminating those without fresh ET and after extensive matching in order to minimize the risk of potential confounding, 18 samples were retained to study two clinical groups: nine biopsies of patients with a live birth versus nine biopsies of patients with an implantation failure, both following fresh ET performed in the same cycle as the biopsy. We studied the proliferative endometrium by analysing its transcriptome and by isolating, culturing and decidualizing EnSCs in vitro. We applied this latter technique for the first time on proliferative endometrial biopsies obtained during ovarian stimulation for in-cycle outcome prediction, in an attempt to overcome inter-cycle variability.

PARTICIPANTS/MATERIALS, SETTING, METHODS

RNA-sequencing was performed for 18 individual whole-tissue endometrial biopsies on an Illumina HiSeq1500 machine. DGE was analysed three times using different approaches (DESeq2, EdgeR and the Wilcoxon rank-sum test, all in R). EnSC isolation and IVD was performed (for 2 and 4 days) for a subset of nine samples, after which media from undifferentiated and decidualized cultures were harvested, stored at -80°C and later assayed for 45 cytokines using a multiplex suspension bead immunoassay. The analysis was performed by partial least squares regression modelling.

MAIN RESULTS AND THE ROLE OF CHANCE

After correction for multiple hypothesis testing, DGE analysis revealed no significant differences between endometrial samples from patients who had a live birth and those with an implantation failure following fresh ET. However secretome analysis after EnSC isolation and culture, showed two distinct clusters that clearly corresponded to the two clinical groups. Upon IVD, the secretome profiles shifted from that of undifferentiated cells but the difference between the two clinical groups remained yet were muted, suggesting convergence of cytokine profiles after decidualization.

LIMITATIONS, REASONS FOR CAUTION

Caution is warranted due to the limited sample size of the study and the in vitro nature of the EnSC experiment. Validation on a larger scale is necessary, however, hard to fulfil given the very limited availability of in-cycle proliferative endometrial biopsies outside a RCT setting.

WIDER IMPLICATIONS OF THE FINDINGS

These data support the hypothesis that the endometrium should be assessed not only during the WOI and that certain endometrial dysfunctionalities can probably be detected early in a cycle by making use of the proliferative phase. This insight opens new horizons for the development of endometrial tests, whether diagnostic or predictive of IVF/ICSI treatment outcome.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by Fonds Wetenschappelijk Onderzoek (FWO, Flanders, Belgium, 11M9415N, 1 524 417N), Wetenschappelijk Fonds Willy Gepts (WFWG G160, Universitair Ziekenhuis Brussel, Belgium) and the National Medicine Research Council (NMRC/CG/M003/2017, Singapore). There are no conflicts of interests.

TRIAL REGISTRATION NUMBER

NCT02061228.

Dysregulation of the interleukin-17A pathway in endometrial tissue from women with unexplained infertility affects pregnancy outcome following assisted reproductive treatment

STUDY QUESTION

Which transcriptomic alterations in mid-luteal endometrial scratch biopsies, taken prior to the assisted reproductive treatment (ART) treatment cycle are associated with unsuccessful pregnancy?

SUMMARY ANSWER

Dysregulated interleukin-17 (IL-17) pathway components are demonstrated in women who fail to become pregnant after ART.

WHAT IS KNOWN ALREADY

Implantation failure is now recognised as a critical factor in unexplained infertility and may be an important component of failed ART.

STUDY DESIGN, SIZE, DURATION

Using a prospective longitudinal study design, 29 nulliparous women with unexplained infertility undergoing ART were recruited between October 2016 and February 2018. Mid-luteal stage endometrium and matched serum samples were collected, and patients underwent a single embryo transfer in the subsequent cycle. RNA-seq analysis of endometrial biopsies was performed on the discovery cohort (n = 20).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Gene set enrichment analysis of the differentially expressed genes (DEGs) was performed. Endometrium and serum were then prepared for IL-17A analysis by ELISA.

MAIN RESULTS AND THE ROLE OF CHANCE

There were 204 differentially expressed protein-coding genes identified in tissue from women who became pregnant (n = 9) compared with tissue from women who failed to become pregnant (n = 11) (false discovery rate; P < 0.05). Of the 204 DEGs, 166 were decreased while 38 were increased in the pregnant compared to the non-pregnant groups. Gene set enrichment analysis of the DEGs identified an over-representation of IL-17 and Pl3K-Akt signalling pathways. All the DEGs within the IL-17 signalling pathway (MMP3, MMP1, IL1β, LCN2, S100A9 and FOSL1) demonstrated decreased expression in the pregnant group. Serum IL-17 protein levels were increased in the non-pregnant discovery cohort (n = 11) and these findings were confirmed a validation cohort (n = 9).

LIMITATIONS, REASONS FOR CAUTION

Limitations of our study include the cohort size and the lack of aneuploidy data for the embryos; however, all embryos transferred were single good or top-quality blastocysts.

WIDER IMPLICATIONS OF THE FINDINGS

These findings demonstrate dysregulated IL-17 pathway components in women who fail to become pregnant after ART. Elevated serum levels of the pro-inflammatory cytokine IL-17 may predict failure of ART in women with unexplained infertility. Future trials of anti-IL-17 therapies in this cohort warrant further investigation.

STUDY FUNDING/COMPETING INTEREST(S)

Funding from the UCD Wellcome Institutional Strategic Support Fund, which was financed jointly by University College Dublin and the SFI-HRB-Wellcome Biomedical Research Partnership (ref 204844/Z/16/Z), is acknowledged. The authors have no competing interests.

TRIAL REGISTRATION NUMBER

NA.

Activation of Blood Vessel Development in Endometrial Stromal Cells In Vitro Cocultured with Human Peri-Implantation Embryos Revealed by Single-Cell RNA-Seq

In humans, the maternal endometrium participates in the physical and physiological interaction with the blastocyst to begin implantation. A bidirectional crosstalk is critical for normal implantation and then a successful pregnancy. While several studies have used animal models or cell lines to study this step, little knowledge was acquired to address the role of endometrial cells in humans. Here, we analyzed single-cell sequencing data from a previous study including 24 non-coculture endometrial stromal cells (EmSCs) and 57 EmSCs after coculture with embryos. We further explored the transcriptomic changes in EmSCs and their interactions with trophoblast cells after coculture. Differentially expressed gene (DEG) analysis showed 1783 upregulated genes and 569 downregulated genes in the cocultured embryos. Weight gene coexpression network and gene ontology analysis of these DEGs showed a higher expression of RAMP1, LTBP1, and LRP1 in EmSCs after coculture, indicating the enrichment of biological processes in blood vessel development and female pregnancy. These data imply that EmSCs start blood vessel development at the implantation stage. Compared with endometrium data in vivo at the implantation window, key pathways including epithelial cell development and oxygen response were involved at this stage. Further analysis using CellphoneDB shed light on the interactions between EmSCs and embryonic trophoblasts, suggesting the important role of integrins and fibroblast growth factor pathways during implantation. Taken together, our work reveals the synchronization signaling and pathways happening at the implantation stage involving the acquisition of receptivity in EmSCs and the interaction between EmSCs and trophoblast cells.

Endometrial extracellular vesicles of recurrent implantation failure patients inhibit the proliferation, migration, and invasion of HTR8/SVneo cells

PURPOSE

Endometrial extracellular vesicles are essential in regulating trophoblasts' function. This study aims to investigate whether endometrial extracellular vesicles (EVs) from recurrent implantation failure (RIF) patients inhibit the proliferation, invasion, and migration of HTR8/SVneo cells.

METHODS

Eighteen RIF patients and thirteen fertile women were recruited for endometria collection. Endometrial cells isolated from the endometria were cultured and modulated by hormones, and the conditioned medium was used for EV isolation. EVs secreted by the endometrial cells of RIF patients (RIF-EVs) or fertile women (FER-EVs) were determined by Western blotting, nanoparticle tracking analysis, and transmission electron microscopy. Fluorescence-labeled EVs were used to visualize internalization by HTR8/SVneo cells. RIF-EVs and FER-EVs were co-cultured with HTR8/SVneo cells. Cell Counting Kit-8, transwell invasion, and wound closure assays were performed to determine cellular proliferation, invasion, and migration, respectively, in different treatments.

RESULTS

RIF-EVs and FER-EVs were bilayer membrane vesicles, ranging from 100 to 150 nm in size, that expressed the classic EV markers Alix and CD9. RIF-EVs and FER-EVs were internalized by HTR8/SVneo cells within 2 h. The proliferation rate in the FER-EV group was significantly higher than that in the RIF-EV group at 20 μg/mL. Moreover, the invasion and migration capacity of trophoblast cells were decreased in the RIF-EV group relative to the FER-EV group at 20 μg/mL.

CONCLUSION

Endometrial EVs from RIF patients inhibited the functions of trophoblasts by decreasing their proliferation, migration, and invasive capacity. Such dysregulations induced by RIF-EVs may provide novel insights for better understanding the pathogenesis of implantation failure.

Endometrial thickness is not predictive for live birth after embryo transfer, even without a cutoff

OBJECTIVE

To investigate the predictive value of endometrial thickness (EMT) for live birth when a lower threshold of EMT is not employed for embryo transfer (ET).

DESIGN

Retrospective study SETTING: Academic assisted reproduction center PATIENT(S): All women who underwent fresh or frozen-thawed ET at the Koç University Hospital Assisted Reproduction Unit between October 2016 and August 2019 INTERVENTION(S): After ruling out endometrial pathology, blastocyst transfer was planned regardless of the EMT in the absence of increased serum progesterone level on the trigger day in fresh embryo transfer cycles or before commencing progesterone treatment in artificially prepared frozen-thawed ET cycles.

MAIN OUTCOME MEASURE(S)

The primary outcome was live birth. Live birth and miscarriage rates per ET were stratified according to fresh and frozen-thawed ET cycles for each millimeter of endometrial thickness. Receiver operator characteristic curve analyses were performed to evaluate the predictive value of EMT for live birth.

RESULT(S)

A total of 560 ET cycles, 273 fresh and 287 frozen-thawed, were included in the study. Relevant patient characteristics as well as EMTs were similar between women who achieved a live birth and those who did not after fresh or frozen-thawed ET. There was no linear association between EMT and live birth or miscarriage rates. Area under the curve values for EMT to predict live birth after fresh, frozen-thawed, and all ETs were 0.56, 0.47, and 0.52, respectively.

CONCLUSION(S)

Our results showed that the EMT was not predictive for live birth in either fresh or frozen-thawed ET cycles. Once intracavitary pathology and inadvertent progesterone exposure were excluded, women with thinner EMTs should not be denied their potential for live birth because it is comparable to that of those with thicker EMT.

Guidelines for biomarker discovery in endometrium: correcting for menstrual cycle bias reveals new genes associated with uterine disorders

Transcriptomic approaches are increasingly used in reproductive medicine to identify candidate endometrial biomarkers. However, it is known that endometrial progression in the molecular biology of the menstrual cycle is a main factor that could affect the discovery of disorder-related genes. Therefore, the aim of this study was to systematically review current practices for considering the menstrual cycle effect and to demonstrate its bias in the identification of potential biomarkers. From the 35 studies meeting the criteria, 31.43% did not register the menstrual cycle phase. We analysed the menstrual cycle effect in 11 papers (including 12 studies) from Gene Expression Omnibus: three evaluating endometriosis, two evaluating recurrent implantation failure, one evaluating recurrent pregnancy loss, one evaluating uterine fibroids and five control studies, which collected endometrial samples throughout menstrual cycle. An average of 44.2% more genes were identified after removing menstrual cycle bias using linear models. This effect was observed even if studies were balanced in the proportion of samples collected at different endometrial stages or only in the mid-secretory phase. Our bias correction method increased the statistical power by retrieving more candidate genes than per-phase independent analyses. Thanks to this practice, we discovered 544 novel candidate genes for eutopic endometriosis, 158 genes for ectopic ovarian endometriosis and 27 genes for recurrent implantation failure. In conclusion, we demonstrate that menstrual cycle progression masks molecular biomarkers, provides new guidelines to unmask them and proposes a new classification that distinguishes between biomarkers of disorder or/and menstrual cycle progression.

Approaches to Improve Endometrial Receptivity in Case of Repeated Implantation Failures

Repeated implantation failures are a constant challenge in reproductive medicine with a significant impact both on health providers and on infertile couples. Several approaches have been proposed so far as effective; however, accumulative data have clarified that most of the treatment options do not have the evidence base for a generalized application to be suggested by the relevant societies. Implantation failures are attributed to either poor quality embryos or to defected endometrial receptivity. The current review aims to summarize in a systematic way all the new trends in managing RIF via interference with endometrial receptivity. The authors focus mainly, but not exclusively, on endometrial injury prior to embryo transfer and endometrial priming with autologous cells or biological agents. To this direction, a systematic search of the Pubmed database has been conducted taking into account the emerged evidence of the last two decades. All the suggested interventions are herein presented and analyzed in terms of reproductive outcomes. It is evident that properly powered and designed randomized trials are needed to support a new standard approach in RIF treatment that will safely be incorporated in national and international guidelines.

Hsa_circ_0038383-mediated competitive endogenous RNA network in recurrent implantation failure

BACKGROUND

Inadequate endometrial receptivity contributes to recurrent implantation failure (RIF) during IVF-embryo transfer. Though multiple circRNAs have been confirmed differentially expression in RIF, the potential function of novel circRNAs needed to be detected.

RESULTS

The top ten DEcircRNAs were selected as initial candidates. A ceRNA network was conducted on the basis of circRNA-miRNA-mRNA potential interaction, consisting of 10 DEcircRNAs, 28 DEmiRNAs and 59 DEmRNAs. Three down-regulation circRNAs with high degree of connectivity were verified by RT-qPCR, and results suggested that only hsa_circ_0038383 was significantly downregulation in RIF compared with control group. Subsequently, three hub genes (HOXA3, HOXA9 and PBX1) were identified as hub genes. Ultimately, a subnetwork was determined based on one DEcircRNA (hsa_circ_0038383), two DEmiRNAs (has-miR-196b-5p and has-miR-424-5p), and three DEmRNAs (HOXA3, HOXA9 and PBX1). Following verification, hsa_circ_0038383/miR-196b-5p/HOXA9 axis may be a key pathway in affecting RIF.

CONCLUSION

In summary, a hsa_circ_0038383-mediated ceRNA network related to RIF was proposed. This network provided new insight into exploring potential biomarkers for diagnosis and clinical treatment of RIF.

METHODS

We retrieved the expression profiles of RIF from GEO databases (circRNA, microRNA and mRNA) and constructed a competing endogenous RNAs (ceRNA) network based on predicted circRNA-miRNA and miRNA-mRNA pairs. The expression levels of three hub DEcircRNAs identified by cytoscape were validated by RT-qPCR.

Uterine disorders affecting female fertility: what are the molecular functions altered in endometrium?

OBJECTIVE

To determine the molecular functions of genes exhibiting altered expression in the endometrium of women with uterine disorders affecting fertility.

DESIGN

Retrospective analysis integrating case and control data from multiple cohorts with endometrium gene expression in women with uterine disorders.

SETTING

Infertility research department affiliated with a university hospital.

PATIENT(S)

Two hundred and forty women, 121 of whom were controls, 119 of whom had endometrial adenocarcinoma (ADC), recurrent implantation failure (RIF), recurrent pregnancy loss (RPL), or stage II-IV endometriosis.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Genomewide gene expression and altered molecular functions in the endometrium of each uterine disorder.

RESULT(S)

Using robust analysis methods, we identified statistically significantly altered endometrial functions in all the uterine disorders. Cell cycle alterations were shared among all the pathologies investigated. Endometriosis was characterized by the down-regulation of ciliary processes. Among the endometriosis, ADC, and RIF samples, mitochondrial dysfunction and protein degradation were shared dysregulated processes. In addition, RPL had the most distinct functional profile, and 95% of affected functions were down-regulated.

CONCLUSION(S)

The most robust functions dysregulated in the endometrium of patients with uterine disorders across sample cohorts implicated an endometrial factor at the gene expression level. This shared endometrial factor affects endometrial receptivity processes.

Determining Diagnostic Criteria of Unexplained Recurrent Implantation Failure: A Retrospective Study of Two vs Three or More Implantation Failure

BACKGROUND

The definition of recurrent implantation failure (RIF) differs clinically, one of the most controversial diagnostic criteria is the number of failed treatment cycles. We tried to investigate whether the two implantation failure could be included in the diagnostic criteria of RIF.

METHODS

A retrospective analysis of the clinical data of patients (N=1518) aged under 40 years with two or more implantation failure, recruited from the Center for Reproductive Medicine of the First Affiliated Hospital of Zhengzhou University from January 2016 to June 2019.

RESULTS

After adjusting for confounding factors by using binary logistic regression, the results showed that partial general information and: distribution of associated factors were significant differences such as maternal age (aOR=1.054, P=0.001), type of cycle (aOR=2.040, P<0.001), stage of embryos development (aOR=0.287, P<0.001), number of embryos transferred (aOR=0.184, P<0.001), female factor (tubal pathology) (aOR=0.432, P=0.031) and male factor (aOR=1.734, P=0.002) between the groups with two and three or more unexplained implantation failure. And further explored whether these differential factors had a significant negative impact on pregnancy outcome, the results showed that: for patients who had three unexplained implantation failure, in the fourth cycle of ET, the live birth rate decreased significantly with age (aOR=0.921, P<0.001), and the live birth rate of blastocyst transfer was significantly higher than that of cleavage embryo transfer (aOR=1.826, P=0.007). At their first assisted pregnancy treatment after the diagnosis of RIF according to these two different definitions, there were no significant difference in the biochemical pregnancy rate, clinical pregnancy rate, ectopic pregnancy rate and abortion rate (P>0.05), but the live birth rate (35.64% vs 42.95%, P=0.004) was significantly different. According to the definition of 'two or more failed treatment cycles', the live birth rate of the first ET treatment after RIF diagnosis was significantly lower than that of patients according to the definition of 'three or more failed treatment cycles'.

CONCLUSION

For patients with unexplained recurrent implantation failure, two implantation failure cannot be included in the diagnostic criteria of RIF. This study supports the generally accepted definition of three or more failed treatment cycles for RIF.

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

BACKGROUND

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

OBJECTIVE AND RATIONALE

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

SEARCH METHODS

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

OUTCOMES

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

WIDER IMPLICATIONS

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

Platelet-activating factor and antiphospholipid antibodies in recurrent implantation failure

Recurrent implantation failure (RIF) refers to cases in which women have had the failure of the embryo implantation after several in vitro fertilization (IVF). The success rate for IVF depends on many different factors. Implantation is a complex step in a successful pregnancy. Antiphospholipid antibodies (aPLs) and platelet-activating factor (PAF) can be considered as effective factors in the embryo implantation. The first purpose of this study is to compare the levels of aPLs and PAF among RIF and fertile control women. The second purpose is evaluating correlations between the blood levels of these factors in this two groups. The levels of twelve types of aPL and PAF in peripheral blood samples of RIF and fertile control women were checked with ELISA method. The results showed that levels of Anti Cardiolipin antibody IgG was above the normal level in 3% of RIF patients. This study examined for the first time the correlation between twelve types of aPLs and PAF in RIF and fertile women. The results of these correlations show that the serum levels of aPLs affects themselves and the serum levels of PAF. The correlation of aPLs levels and PAF levels was different in the two groups. Differences in the correlations of aPLs levels and PAF levels in two groups show that the equal changes in the level of variables examined can have different effects in RIF and the fertile control groups. It is suggested that the correlation between these variables be evaluated in other studies.

A Novel Molecule in Human Cyclic Endometrium: LncRNA TUNAR Is Involved in Embryo Implantation

Embryo implantation rate remains an inefficient process in in vitro fertilization and embryo transfer (IVF-ET) cycles. The role long non-coding RNA (lncRNA) plays in embryo implantation remains unclear. We aimed to investigate the expression pattern of lncRNA TCL1 upstream neural differentiation-associated RNA (TUNAR) in human cyclic endometrium and clarify the role of TUNAR in the development of endometrial receptivity. Endometrial biopsies were collected at the late proliferative phase, luteinizing hormone (LH) + 2 and LH + 7, from patients with or without recurrent implantation failure (RIF). Real-time RT PCR was performed to detect the level of lncRNAs. After pZW1-snoVector-TUNAR transfection, multiple function of TUNAR in endometrial epithelial cells (EECs) and endometrial stromal cells (ESCs) was investigated. The expression of TUNAR in endometrium was found down-regulated at LH + 7 and up-regulated in RIF patients. In proliferative phase, TUNAR was overwhelmingly more abundant in ESCs and regulated its proliferation. In LH + 7, the difference in the expression of TUNAR between ESCs and EECs was narrowed. Overexpression of TUNAR not only impaired spheroid attachment to EECs, but also inhibited decidualization of ESCs. TUNAR was found expressed in human endometrium for the first time, which might be involved in embryo implantation by modulating the blastocyst attachment to the endometrial epithelium and regulating the proliferation and decidualization of ESCs. Our study helps us to better understand the molecular mechanisms of embryo implantation and may provide a promising biomarker of endometrial receptivity.

The genomic analysis of endometrial mitochondrial DNA copy number variation on recurrent implantation failure

OBJECTIVE

Aim of this study was to define the relationship between RIF (Recurrent Implantation Failure) and endometrial mtDNA copy number.

STUDY DESIGN

A total of 50 women of reproductive age including twenty-five patients clinically diagnosed with RIF and twenty-five fertile women as healthy controls were recruited into the study. Endometrial biopsy samples were obtained with a pipelle at the 20-24 days of the menstrual cycle of each participant. Total genomic DNA samples were isolated from endometrial tissues; MT-ND1 (mitochondrially encoded NADH dehydrogenase I) and MT-CO2 (mitochondrially encoded cytochrome C oxidase II) target genes were amplified by droplet digital PCR (ddPCR). Nuclear GAPDH (Glyceraldehyde-3-Phosphate Dehydrogenase) gene was also used for study normalization. The study has been conducted between February 2019 and June 2019.

RESULT(S)

Droplet digital PCR results were analyzed in "QuantaSoft" software. The concentration amount (copies/μl) of each participant's mitochondrial gene was normalized according to the GAPDH gene concentrations as nuclear reference. mtDNA amounts were compared between RIF patients and healthy controls. Normalized data was statistically evaluated using Mann-Whitney U test and ROC curve analysis.

CONCLUSION(S)

It was concluded that the mitochondrial target gene (MT-ND1 and MT-CO2) copy number amount of RIF patients was higher than the one obtained from the healthy group in endometrial tissues. It is thought that higher mtDNA copy number at the RIF group may be related to increased oxidative stress in the endometrium. This stress factors may influence receptivity negatively and cause implantation failure. The receptivity of the endometrium is associated with the number of mtDNA copies and difference can be used as a biomarker for receptivity analysis.

Evaluation of the endometrial receptivity assay and the preimplantation genetic test for aneuploidy in overcoming recurrent implantation failure

PURPOSE

To evaluate the clinical usefulness of the endometrial receptivity array (ERA) and the preimplantation genetic test for aneuploidy (PGT-A) in patients with severe and moderate recurrent implantation failure (RIF).

DESIGN

A retrospective multicenter cohort study was conducted in patients who failed to achieve implantation following transfer of 3 or more or 5 or more embryos in at least three single embryo transfers; patients were classified as moderate or severe RIF, respectively. Patients with previous RIF were compared based on the testing they received: PGT-A, ERA, or PGT-A+ERA versus a control group with no testing. Mean implantation rate and ongoing pregnancy rates per embryo transfer were considered primary outcomes. Multiple logistic regression analysis was performed and adjusted ORs were calculated to control possible bias.

RESULTS

Of the 2110 patients belonging to the moderate RIF group, those who underwent transfer of euploid embryos after PGT-A had a higher implantation rate than those who did not. Additionally, the PGT-A group had a significantly higher rate of ongoing pregnancy. The same outcomes measured for the 488 patients in the severe RIF group did not reveal any statistically significant improvements. The use of the ERA test did not appear to significantly improve outcomes in either group.

CONCLUSIONS

PGT-A may be beneficial for patients with moderate recurrent implantation failure but not for severe cases. At its current level of development, ERA does not appear to be clinically useful for patients with RIF.

What is the prognosis for a live birth after unexplained recurrent implantation failure following IVF/ICSI?

STUDY QUESTION

What is the cumulative incidence of live birth and mean time to pregnancy (by conception after IVF/ICSI or natural conception) in women experiencing unexplained recurrent implantation failure (RIF) following IVF/ICSI treatment?

SUMMARY ANSWER

In 118 women who had experienced RIF, the reported cumulative incidence of live birth during a maximum of 5.5 years follow-up period was 49%, with a calculated median time to pregnancy leading to live birth of 9 months after diagnosis of RIF.

WHAT IS KNOWN ALREADY

Current definitions of RIF include failure to achieve a pregnancy following IVF/ICSI and undergoing three or more fresh embryo transfer procedures of one or two high quality embryos or more than 10 embryos transferred in fresh or frozen cycles. The causes and optimal management of this distressing condition remain uncertain and a range of empirical and often expensive adjuvant therapies is often advocated. Little information is available regarding the long-term prognosis for achieving a pregnancy.

STUDY DESIGN, SIZE, DURATION

Two hundred and twenty-three women under 39 years of age who had experienced RIF without a known cause after IVF/ICSI treatment in two tertiary referral university hospitals between January 2008 and December 2012 were invited to participate in this retrospective cohort follow up study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All eligible women were sent a letter requesting their consent to the anonymous use of their medical file data and were asked to complete a questionnaire enquiring about treatments and pregnancies subsequent to experiencing RIF. Medical files and questionnaires were examined and results were analysed to determine the subsequent cumulative incidence of live birth and time to pregnancy within a maximum 5.5 year follow-up period using Kaplan Meier analysis. Clinical predictors for achieving a live birth were investigated using a Cox hazard model.

MAIN RESULTS AND THE ROLE OF CHANCE

One hundred and twenty-seven women responded (57%) and data from 118 women (53%) were available for analysis. During the maximum 5.5 year follow up period the overall cumulative incidence of live birth was 49% (95% CI 39-59%). Among women who gave birth, the calculated median time to pregnancy was 9 months after experiencing RIF, where 18% arose from natural conceptions.

LIMITATIONS, REASONS FOR CAUTION

Since only 57% of the eligible study cohort completed the questionnaire, the risk of response bias limits the applicability of the study findings.

WIDER IMPLICATIONS OF THE FINDINGS

This study reports a favorable overall prognosis for achieving live birth in women who have previously experienced RIF, especially in those who continue with further IVF/ICSI treatments. However since 51% did not achieve a live birth during the follow-up period, there is a need to distinguish those most likely to benefit from further treatment. In this study, no clinical factors were found to be predictive of those achieving a subsequent live birth.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the University Medical Center Utrecht, in Utrecht and the Academic Medical Centre, in Amsterdam. NSM has received consultancy and speaking fees and research funding from Ferring, MSD, Merck Serono, Abbott, IBSA, Gedion Richter, and Clearblue. During the most recent 5-year period BCJMF has received fees or grant support from the following organizations (in alphabetic order); Actavis/Watson/Uteron, Controversies in Obstetrics & Gynecology (COGI), Dutch Heart Foundation, Dutch Medical Research Counsel (ZonMW), Euroscreen/Ogeda, Ferring, London Womens Clinic (LWC), Merck Serono, Myovant, Netherland Genomic Initiative (NGI), OvaScience, Pantharei Bioscience, PregLem/Gedeon Richter/Finox, Reproductive Biomedicine Online (RBMO), Roche, Teva, World Health Organisation (WHO).None of the authors have disclosures to make in relation to this manuscript.

Trophoblast attachment to the endometrial epithelium elicits compartment-specific transcriptional waves in an in-vitro model

RESEARCH QUESTION

Which are the early compartment-specific transcriptional responses of the trophoblast and the endometrial epithelium throughout early attachment during implantation?

DESIGN

An endometrial epithelium proxy (cell line Ishikawa) was co-cultured with spheroids of a green fluorescent protein (GFP) expressing trophoblast cell line (JEG-3). After 0, 8 and 24 h of co-culture, the compartments were sorted by fluorescence-activated cell sorting; GFP+ (trophoblast), GFP- (epithelium) and non-co-cultured control populations were analysed (in triplicate) by RNA-seq and gene set enrichment analysis (GSEA).

RESULTS

Trophoblast challenge induced a wave of transcriptional changes in the epithelium that resulted in 295 differentially regulated genes involving epithelial to mesenchymal transition (EMT), cell movement, apoptosis, hypoxia, inflammation, allograft rejection, myogenesis and cell signalling at 8 h. Interestingly, many of the enriched pathways were subsequently de-enriched by 24 h (i.e. EMT, cell movement, allograft rejection, myogenesis and cell signalling). In the trophoblast, the co-culture induced more transcriptional changes and regulation of a variety of pathways. A total of 1247 and 481 genes were differentially expressed after 8 h and from 8 to 24 h, respectively. Angiogenesis and hypoxia were over-represented at both stages, while EMT and cell signalling only were at 8 h; from 8 to 24 h, inflammation and oestrogen response were enriched, while proliferation was under-represented.

CONCLUSIONS

Successful attachment produced a series of dynamic changes in gene expression, characterized by an overall early and transient transcriptional up-regulation in the receptive epithelium, in contrast to a more dynamic transcriptional response in the trophoblast.

The endometrial proteomic profile around the time of embryo implantation†

Embryo implantation is an intricate process which requires competent embryo and receptive endometrium. The failure of endometrium to achieve receptivity is a recognized cause of infertility. However, due to multiplicity of events involved, the molecular mechanisms governing endometrial receptivity are still not fully understood. Traditional one-by-one approaches, including western blotting and histochemistry, are insufficient to examine the extensive changes of endometrial proteome. Although genomics and transcriptomics studies have identified several significant genes, the underlying mechanism remains to be uncovered owing to post-transcriptional and post-translational modifications. Proteomic technologies are high throughput in protein identification, and they are now intensively used to identify diagnostic and prognostic markers in the field of reproductive medicine. There is a series of studies analyzing endometrial proteomic profile, which has provided a mechanistic insight into implantation failure. These published studies mainly focused on the difference between pre-receptive and receptive stages of endometrium, as well as on the alternation of endometrial proteomics in women with reproductive failure. Here, we review recent data from proteomic analyses regarding endometrium around the time of embryo implantation and propose possible future research directions.

Endometrial extracellular vesicles from women with recurrent implantation failure attenuate the growth and invasion of embryos

OBJECTIVE

To investigate whether endometrial extracellular vesicles (EVs) from patients with recurrent implantation failure (RIF) attenuate the growth and invasion of embryos.

DESIGN

In vitro experimental study.

SETTING

University-affiliated hospital.

PATIENT(S)

Ten RIF patients and seven fertile women.

INTERVENTIONS(S)

Endometrial cells isolated from endometrial tissues obtained from patients with RIF and fertile women were cultured and modulated in vitro via hormones. Conditioned medium was collected for EV isolation.

MAIN OUTCOME MEASURE(S)

EVs secreted by endometrial cells of patients with RIF (RIF-EVs) or fertile women (FER-EVs) were characterized with the use of Western blotting, nanoparticle tracking analysis, and transmission electron microscopy. EVs from the two groups were co-cultured with 2-cell murine embryos. Fluorescence-labeled EVs were used to visualize internalization by embryos. Following co-culture, blastocyst and hatching rates were calculated. Blastocysts were stained with diamidino-2-phenylindole to count the total cell number, and the hatched embryos were used to test invasion capacity.

RESULT(S)

RIF-EVs and FER-EVs are bilayered vesicles ∼100 nm in size and enriched with TSG101, Alix, and CD9. EVs were internalized within 12 hours. The blastocyst rates in the RIF-EV groups were significantly decreased compared with the FER-EV groups at 5, 10, and 20 μg/mL. The hatching rates and total cell numbers of blastocysts also were decreased significantly in the RIF-EV groups compared with the FER-EV groups at 10 and 20 μg/mL. Moreover, the invasion capacity of hatched embryos decreased significantly in the RIF-EV group.

CONCLUSION(S)

Endometrial EVs from patients with RIF attenuate the development and invasion of embryos.

Molecular signature of eutopic endometrium in endometriosis based on the multi-omics integrative synthesis

PURPOSE

To synthesise data from genome-wide studies reporting molecular signature of eutopic endometrium through the phases of the menstrual cycle in endometriosis.

METHODS

Extraction of data from publications reporting genetic signatures characterising endometrium associated with endometriosis. The nomenclature of extracted differentially expressed transcripts and proteins was adopted according to the HUGO Gene Nomenclature Committee (HGNC). Loci were further sorted according to the different phases of the menstrual cycle, i.e. menstrual (M), proliferative (P), secretory (S), early-secretory (ES), mid-secretory (MS), late-secretory (LS), and not specified (N/S) if the endometrial dating was not available. Enrichment analysis was performed using the DAVID bioinformatics tool.

RESULTS

Altered molecular changes were reported by 21 studies, including 13 performed at the transcriptomic, 6 at proteomic, and 2 at epigenomic level. Extracted data resulted in a catalogue of total 670 genetic causes with available 591 official gene symbols, i.e. M = 3, P = 188, S = 81, ES = 82, MS = 173, LS = 36, and N/S = 28. Enriched pathways included oestrogen signalling pathway, extracellular matrix organization, and endothelial cell chemotaxis. Our study revealed that knowledge of endometrium biology in endometriosis is fragmented due to heterogeneity of published data. However, 15 genes reported as dysregulated by at least two studies within the same phase and 33 significantly enriched GO-BP terms/KEGG pathways associated with different phases of the menstrual cycle were identified.

CONCLUSIONS

A multi-omics insight into molecular patterns underlying endometriosis could contribute towards identification of endometrial pathological mechanisms that impact fertility capacities of women with endometriosis.

Therapeutic endometrial scratching and implantation after in vitro fertilization: a multicenter randomized controlled trial

OBJECTIVE

To study whether endometrial scratching in the luteal phase before ovarian stimulation increases clinical pregnancy rates in women with one or more previous implantation failures.

DESIGN

A nonblinded multicenter randomized clinical trial.

SETTING

Fertility clinics.

PATIENT(S)

Three hundred four eligible patients scheduled for IVF/intracytoplasmic sperm injection were randomized. The intervention group (n = 151) underwent endometrial scratching in the luteal phase before controlled ovarian stimulation, while no intervention was performed in the control group (n = 153).

INTERVENTION(S)

Endometrial scratching with a Pipelle de Cornier catheter in the luteal phase before ovarian stimulation.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy rate and prenatal and birth data.

RESULT(S)

There was no overall significant improvement in clinical pregnancy rates between the control and intervention groups (38.5% vs. 44.4%; relative risk = 1.15; confidence interval [0.86-1.55]). However, subgroup analyses revealed that women with three or more previous implantation failures had a significant increase in clinical pregnancy rate (31.1% vs. 53.6%; relative risk = 1.72; confidence interval [1.05-2.83]) after scratching. No difference was seen as regards prenatal and birth data between the two groups.

CONCLUSION(S)

Endometrial scratching in the luteal phase before ovarian stimulation significantly enhances the clinical pregnancy rate in women with three or more prior implantation failures. This result seems to corroborate previous reports, which found that particularly women with repeated implantation failure seem to gain a positive effect from endometrial scratching. Importantly, there were no significant differences in prenatal data and birth data between the groups.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01963819.

Identification of key genes, regulatory factors, and drug target genes of recurrent implantation failure (RIF)

Objective: Recurrent implantation failure (RIF) exacerbates the physical trauma of infertile women that undergone in vitro fertilization-embryo transfer (IVF-ET). We aimed to identify the key genes, regulatory factors, and drug target genes involved in the RIF.Methods: The dataset GSE58144 that obtained from the Gene Expression Omnibus mainly contained 43 RIF and 72 control endometrial samples. Differently expressed genes (DEGs) between RIF and control groups were firstly analyzed, followed by the pathway and Gene Ontology (GO) enrichment analysis. Then, protein-protein interaction (PPI) network and miRNA-transcript factor (TF)-DEGs network were established. Finally, a drug-target interaction network was constructed.Results: A total of 399 DEGs were identified between the RIF and controls. In the PPI and key module network, UBE2I, PLK4, XPO1, AURKB, and NUP107 were identified as the hub genes, which mainly enriched in RNA transport and cell division cycle-related pathways and GO items. In the miRNA-TF-DEGs network, E2F4, SIN3A, miRNA489, miRNA199A, miRNA369-3P, miRNA422, and miRNA522 were considered as the key regulatory factors during RIF. In addition, HTR1A, NR3C1, and GABRA3 were the main targets of the drugs annotated in DrugBank.Conclusion: The effects of PLK4, XPO1, AURKB, and NUP107 on the RIF may be via affecting the proliferation and differentiation of endometrial stromal cells. Besides, SIN3A and miRNA199A may be crucial for embryo implantation. In addition, NR3C1 may be used as a possible target for the clinical therapy of RIF.

Premature expression of the decidualization marker prolactin is associated with repeated implantation failure

Repeated implantation failure (RIF) is a poorly understood reproductive pathology defined by the inability to achieve a clinical pregnancy in at least three consecutive IVF cycles. In this study, we investigated whether the onset of decidualization, marked by prolactin (PRL) expression, is associated with RIF. We performed a retrospective cohort study using endometrial biopsies from women with idiopathic subfertility, that conceived naturally during the same cycle in which the biopsy was taken (group 1; n = 15) conceived naturally within three months after the biopsy was taken (group 2; n = 20), or unsuccessfully underwent six IUI cycles and three IVF cycles with transfer of at least one high-quality embryo (group 3, RIF; n = 20). Our results demonstrated that immunohistochemical PRL-staining was present in 8/15 women from group 1 (53.3%), in 1/20 women from group 2 (5.0%), and in 11/20 women from group 3 (55.0%). Increased proliferation, analyzed by Ki67 expression, was seen in women that were pregnant during the biopsy, compared to all women combined that were not pregnant (p≤.01). In conclusion, our study demonstrates that premature expression of the decidualization marker PRL during the luteal phase is associated with RIF.

Interferon tau-dependent and independent effects of the bovine conceptus on the endometrial transcriptome†

This study investigated bovine conceptus-induced modifications to the endometrial transcriptome related to effects of interferon tau (IFNT), conceptus origin (in vivo vs. in vitro), and conceptus sex. In vitro (IVF) or in vivo (superovulation and artificial insemination, AI) produced blastocysts were transferred into recipient heifers on day 7 of the estrous cycle. On day 15, IVF- or AI-derived conceptuses were obtained by uterine flushing and individually placed on endometrial explants in media for 6 h. Explants were also cultured with media alone as a control or media containing 100 ng/mL IFNT. Total explant RNA was analyzed by RNA-Seq. Incubation of endometrium with IFNT or IVF- or AI-derived conceptuses changed (P ≤ 0.001) expression of 491, 498, and 576 transcripts, respectively, compared to the control. Further, 369 differentially expressed genes (DEGs) were common between explants exposed to IFNT or a conceptus. A total of 240 DEGs were uniquely altered by conceptuses (IVF- and AI-derived) but not IFNT. Of these transcripts, 46 were shared between the IVF and AI groups, while 61 and 133 were specific to IVF and AI conceptuses, respectively. Five genes [melanophilin (MLPH), prominin-2 (PROM2), myeloid associated differentiation marker (MYADM), vomeronasal 1 receptor 4 like (VN1R4L) and 5-hydroxytryptamine receptor 1A (HTR1A)] were more abundant in endometrium exposed to female compared to male conceptuses (P < 0.001). A single gene [ADP-ribosylation factor like GTPase 4C (ARL4C)] was more abundant in response to male conceptuses (P < 0.001) than female conceptuses. These data support the hypothesis that conceptus regulation of gene expression in the endometrium is complex and involves factors other than IFNT that may have a biological role in pregnancy establishment.

Uterine aquaporin expression is dynamically regulated by estradiol and progesterone and ovarian stimulation disrupts embryo implantation without affecting luminal closure

The study investigated the effect of normal and supraphysiological (resulting from gonadotropin-dependent ovarian stimulation) levels of estradiol (E2) and progesterone (P4) on mouse uterine aquaporin gene/protein (Aqp/AQP) expression on Day 1 (D1) and D4 of pregnancy. The study also examined the effect of ovarian stimulation on uterine luminal closure and uterine receptivity on D4 of pregnancy and embryo implantation on D5 and D7 of pregnancy. These analyses revealed that the expression of Aqp3, Aqp4, Aqp5 and Aqp8 is induced by E2 while the expression of Aqp1 and Aqp11 is induced by P4. Additionally, P4 inhibits E2 induction of Aqp3 and Aqp4 expression while E2 inhibits Aqp1 and Aqp11 expression. Aqp9, however, is constitutively expressed. Ovarian stimulation disrupts Aqp3, Aqp5 and Aqp8 expression on D4 and AQP1, AQP3 and AQP5 spatial expression on both D1 and D4, strikingly so in the myometrium. Interestingly, while ovarian stimulation has no overt effect on luminal closure and uterine receptivity, it reduces implantation events, likely through a disruption in myometrial activity and embryo development. The wider implication of this study is that ovarian stimulation, which results in supraphysiological levels of E2 and P4 and changes (depending on the degree of stimulation) in the E2:P4 ratio, triggers abnormal expression of uterine AQP during pregnancy, and this is associated with implantation failure. These findings lead us to recognize that abnormal expression would also occur under any pathological state (such as endometriosis) that is associated with changes in the normal E2:P4 ratio. Thus, infertility among these patients might in part be linked to abnormal uterine AQP expression.

Diagnostic and therapeutic options in recurrent implantation failure

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

Transcriptomic changes and potential regulatory mechanism of intrauterine human chorionic gonadotropin co-cultured with peripheral blood mononuclear cells infusion in mice with embryonic implantation dysfunction

Background

This study aimed to explore whether intrauterine infusion of peripheral blood mononuclear cells (PBMCs) could induce favorable transcriptomic changes in the endometrium for embryo implantation and the potential mechanism.

Methods

Twenty-one mice were randomly divided to five groups, including a normal pregnancy (NP) group, an embryo implantation dysfunction (EID) group, an EID with human chorionic gonadotropin (hCG) group, an EID with PBMCs group, and an EID with hCG co-cultured with PBMCs group. The endometrium in the implantation window from mice were collected and determined by RNA sequencing (RNA-Seq), and the expression of significantly different genes with high degree of coincidence was recommended and validated by quantitative real-time polymerase chain reaction (qRT-PCR).

Results

There were totally 1,366 up-regulated and 1,374 down-regulated genes in the EID mice compared with the normal pregnant mice. We selected (fold change ≥2, P<0.05) and verified the candidate genes associated with embryo implantation, immune response and other reproductive processes in previous reports by qRT-PCR. Leukemia inhibitory factor (LIF), solute carrier family 15 member 2 (SLC15A2), retinoic acid receptor responder 1 (RARRES1), vascular cell adhesion molecule 1 (VCAM1) were down-regulated and musculin (MSC), chemokine (C-X-C motif) ligand 14 (CXCL14) were up-regulated significantly in EID group (P<0.05), and the synergistic effects of hCG were seen. In addition, the expression of glucocorticoid receptor (GR)-β in PBMCs of NP mice was higher than that of EID mice, and up-regulated GR-β in EID mice could significantly increase the expression of LIF, SLC15A2, RARRES1 and VCAM1, and decrease the expression of CXCL14 and MSC, which indicated GR-β might be a transcriptional factor of the six genes above.

Conclusions

Intrauterine PBMCs perfusion might improve the performance of impaired endometrial receptivity by regulating LIF, SLC15A2, RARRES1, VCAM1, MSC as well as CXCL14, and hCG could enhance the effect of PBMCs. In addition, GR-β, as a transcriptional factor, could regulate the six genes in PBMCs.

Analysis of the uterine lumen in fertility-classified heifers: II. Proteins and metabolites†

Survival and growth of the bovine conceptus is dependent on endometrial secretions or histotroph. Previously, serial blastocyst transfer was used to classify heifers as high fertile (HF), subfertile (SF), or infertile (IF). Here, we investigated specific histotroph components (proteins and metabolites) in the uterine lumen of day 17 fertility-classified heifers. Interferon tau (IFNT) was more abundant in uterine lumenal fluid (ULF) of pregnant HF than SF animals as the conceptus was longer in HF heifers. However, no differences in endometrial expression of selected classical and nonclassical interferon-stimulated genes (ISGs) were observed, suggesting that IFNT signaling in the endometrium of pregnant HF and SF heifers was similar. Pregnancy significantly increased the abundance of several proteins in ULF. Based on functional annotation, the abundance of a number of proteins involved in energy metabolism, oxidative stress, amino acid metabolism, and cell proliferation and differentiation were greater in the ULF of pregnant HF than SF heifers. Metabolomics analysis found that pregnancy only changed the metabolome composition of ULF from HF heifers. The majority of the metabolites that increased in the ULF of pregnant HF as compared to SF heifers were associated with energy and amino acid metabolism. The observed differences in ULF proteome and metabolome are hypothesized to influence uterine receptivity with consequences on conceptus development and survival in fertility-classified heifers.

Development of the human placenta

The placenta is essential for normal in utero development in mammals. In humans, defective placental formation underpins common pregnancy disorders such as pre-eclampsia and fetal growth restriction. The great variation in placental types across mammals means that animal models have been of limited use in understanding human placental development. However, new tools for studying human placental development, including 3D organoids, stem cell culture systems and single cell RNA sequencing, have brought new insights into this field. Here, we review the morphological, molecular and functional aspects of human placental formation, with a focus on the defining cell of the placenta - the trophoblast.

Genome-wide analysis of long noncoding RNAs, microRNAs, and mRNAs forming a competing endogenous RNA network in repeated implantation failure

Repeated implantation failure (RIF) was mainly due to poor endometrium receptivity. Long noncoding RNAs (lncRNAs) could regulate endometrium receptivity and act in competing endogenous RNA (ceRNA) theory. However, the regulatory mechanism of the lncRNA-miRNA-mRNA network in repeated implantation failure (RIF) is unclear. We obtained RIF-related expression profiles of lncRNAs, mRNAs, and miRNAs using mid-secretory endometrial tissue samples from 5 women with RIF and 5 controls by RNA-sequencing. Co-expression analysis revealed that three functional modules were enriched in immune response/inflammation process; two functional modules were enriched in metabolic/ biosynthetic process, and one functional module were enriched in cell cycle pathway. By adding the miRNA data, ceRNA regulatory relationship of each module was reconstructed. The ceRNA network of the whole differentially expressed RNAs revealed 10 hub lncRNAs. Among them, TRG-AS1, SIMM25, and NEAT1 were involved in the module1, module2, and module3, respectively; LNC00511 and SLC26A4-AS1 in the module4; H19 in the module5. The real-time polymerase chain reaction (RT-PCR) results of 15 randomly selected RNAs were consistent with our sequencing data. These can be used as novel potential biomarkers for RIF. Furthermore, they might be involved in endometrium receptivity by acting as ceRNA.

MRP4 sustains Wnt/β-catenin signaling for pregnancy, endometriosis and endometrial cancer

Rationale: Abnormal Wnt/β-catenin signaling in the endometrium can lead to both embryo implantation failure and severe pathogenic changes of the endometrium such as endometrial cancer and endometriosis. However, how Wnt/β-catenin signaling is regulated in the endometrium remains elusive. We explored possible regulation of Wnt/β-catenin signaling by multi-drug resistance protein 4 (MRP4), a potential target in cancer chemotherapy, and investigated the mechanism.

Methods: Knockdown of MRP4 was performed in human endometrial cells in vitro or in a mouse embryo-implantation model in vivo. Immunoprecipitation, immunoblotting and immunofluorescence were used to assess protein interaction and stability. Wnt/β-catenin signaling was assessed by TOPflash reporter assay and quantitative PCR array. Normal and endometriotic human endometrial tissues were examined. Data from human microarray or RNAseq databases of more than 100 participants with endometriosis, endometrial cancer or IVF were analyzed. In vitro and in vivo tumorigenesis was performed.

Results: MRP4-knockdown, but not its transporter-function-inhibition, accelerates β-catenin degradation in human endometrial cells. MRP4 and β-catenin are co-localized and co-immunoprecipitated in mouse and human endometrium. MRP4-knockdown in mouse uterus reduces β-catenin levels, downregulates a series of Wnt/β-catenin target genes and impairs embryo implantation, which are all reversed by blocking β-catenin degradation. Analysis of human endometrial biopsy samples and available databases reveals significant and positive correlations of MRP4 with β-catenin and Wnt/β-catenin target genes in the receptive endometrium in IVF, ectopic endometriotic lesions and endometrial cancers. Knockdown of MRP4 also inhibits in vitro and in vivo endometrial tumorigenesis.

Conclusion: A previously undefined role of MRP4 in stabilizing β-catenin to sustain Wnt/β-catenin signaling in endometrial cells is revealed for both embryo implantation and endometrial disorders, suggesting MRP4 as a theranostic target for endometrial diseases associated with Wnt/β-catenin signaling abnormality.

iTRAQ comparison of proteomic profiles of endometrial receptivity

Endometrial receptivity is a limiting step in human reproduction. A disruption in the development of endometrial receptivity is responsible for recurrent implantation failures (RIF) of endometrial origin. To understand the molecular mechanisms behind the endometrial receptivity process, we used the isobaric tag for relative and absolute quantitation (iTRAQ) method to compare three different endometrial statuses: fertile women, intrauterine device (IUD) carriers, and RIF patients. Overall, iTRAQ allowed identified 1889 non-redundant proteins. Of these, 188 were differentially expressed proteins (DEP) (p-value < .05). Pairwise comparisons revealed 133 significant DEP in fertile vs. IUD carriers and 158 DEP in RIF vs. IUD carriers. However, no DEP were identified between fertile and RIF patients. Western blot validation of three DEP involved in endometrial receptivity (plastin 2, lactotransferrin, and lysozyme) confirmed our iTRAQ results. Moreover, functional KEGG enrichment revealed that complement and coagulation cascades and peroxisome were the two most significant pathways for the RIF vs. IUD comparison and ribosome and spliceosome for the fertile vs. IUD comparison, as possible important pathways involved in the endometrial receptivity acquisition. The lack of DEP between fertile and RIF patient endometria suggest that idiopathic RIF may not have an endometrial origin, with other as-yet-unknown factors involved. SIGNIFICANCE: A pilot study where a comparison of the endometrial protein profile from women with different endometrial receptive grade (fertile women, IUD carriers and RIF patients) during the same period of time (overlapping with the window of implantation) of a hormone replacement therapy was performed using a high-throughput proteomic technique. This approach lead us to better understand the molecular mechanisms undergoing endometrial receptivity, a time-limiting step to achieve pregnancy in humans. Moreover, the number of samples per group (10 Fertile women, 10 IUD carriers and 8 RIF patients) according to the methodology here employed (8plex iTRAQ), give more robustness to our results. Our findings confirm that an IUD introduces numerous changes in the endometrial protein profile when compared to fertile and RIF endometria, revealing some key proteins involved in endometrial receptivity. Finding no significant differences between Fertile and RIF patient endometria could suggest that other as-yet-unknown factors could be involved in the etiology of idiopathic RIF.

Early growth response 1 transcriptionally primes the human endometrial stromal cell for decidualization

Mouse studies support a role for endometrial early growth response 1 (EGR1) in uterine receptivity and decidualization, which are processes controlled by estrogen and progesterone. However, the importance of this transcription factor in similar cellular processes in human is unclear. Analysis of clinical samples indicate that endometrial EGR1 levels are decreased in the endometrium of women with recurrent implantation failure, suggesting that tight control of EGR1 levels are necessary for normal endometrial function. Therefore, we used siRNA-mediated knockdown of EGR1 expression in cultured human endometrial stromal cells (hESCs) to assess the functional role of EGR1 in hESC decidualization. Protein expression studies revealed that EGR1 is highly expressed in pre-decidual hESCs. However, EGR1 protein levels rapidly decrease following administration of an established deciduogenic hormone stimulus containing estradiol, medroxyprogesterone acetate, and cyclic adenosine monophosphate. Intriguingly, EGR1 knockdown in pre-decidual hESCs blocks the ability of these cells to decidualize later, indicating that EGR1 is required to transcriptionally program pre-decidual hESCs for decidualization. Support for this proposal comes from the analysis of transcriptome and cistrome datasets, which shows that EGR1 target genes are primarily involved in transcriptional regulation, cell signaling, and proliferation. Collectively, our studies provide translational support for an evolutionary conserved role for human endometrial stromal EGR1 in the early events of pregnancy establishment.

Transcriptomic analysis of the interaction of choriocarcinoma spheroids with receptive vs. non-receptive endometrial epithelium cell lines: an in vitro model for human implantation

PURPOSE

Several in vitro systems have been reported to model human implantation; however, the molecular dynamics of the trophoblast vs. the epithelial substrate during attachment have not been described. We have established an in vitro model which allowed us to dissect the transcriptional responses of the trophoblast and the receptive vs. non-receptive epithelium after co-culture.

METHODS

We established an in vitro system based on co-culture of (a) immortalized cells representing receptive (Ishikawa) or non-receptive (HEC-1-A) endometrial epithelium with (b) spheroids of a trophoblastic cell line (JEG-3) modified to express green fluorescent protein (GFP). After 48 h of co-culture, GFP+ (trophoblast cells) and GFP- cell fractions (receptive or non-receptive epithelial cells) were isolated by fluorescence-activated flow cytometry (FACS) and subjected to RNA-seq profiling and gene set enrichment analysis (GSEA).

RESULTS

Compared to HEC-1-A, the trophoblast challenge to Ishikawa cells differentially regulated the expression of 495 genes, which mainly involved cell adhesion and extracellular matrix (ECM) molecules. GSEA revealed enrichment of pathways related to cell division, cell cycle regulation, and metabolism in the Ishikawa substrate. Comparing the gene expression profile of trophoblast spheroids revealed that 1877 and 323 genes were upregulated or downregulated when co-cultured on Ishikawa substrates (compared to HEC-1-A), respectively. Pathways favorable to development, including tissue remodeling, organogenesis, and angiogenesis, were enhanced in the trophoblast compartment after co-culture of spheroids with receptive epithelium. By contrast, the co-culture with less receptive epithelium enriched pathways mainly related to trophoblast cell proliferation and cell cycle regulation.

CONCLUSIONS

Endometrial receptivity requires a transcriptional signature that determines the trophoblast response and drives attachment.

Implantation failure of endometrial origin: what is new?

PURPOSE OF REVIEW

To review recent findings related to possible causes of recurrent implantation failure of endometrial origin in normal uterus.

RECENT FINDINGS

Recent evidences suggest that in apparently normal endometria, RIF may associate with molecular and functional changes in the uterus such as abnormal endometrial microbiota, including the presence of chronic endometritis, poor synchronization between the blastocyst and endometrium, and/or excessive uterine peristalsis. An altered endometrial microbiota detected by molecular techniques has been recently related to poorer embryo implantation, even in apparently normal endometria. The use of the endometrial receptivity analysis test to obtain an objective signature of endometrial receptivity has shown to improve the reproductive performance in RIF patients. The diagnosis of uterine peristalsis, however, remains challenging since the usual evaluation by transvaginal ultrasound is not accurate, and drugs tested to reduce uterine peristalsis and enhance embryo implantation have not been clearly beneficial. Finally, endometrial injury to improve implantation rates remains controversial being definitive well-designed trials needed to assess its benefit, if any.

SUMMARY

In recurrent implantation failure of endometrial origin an altered pattern of the microbial endometrial ecosystem, a displaced window of implantation leading to desynchronization between the blastocyst and the endometrium, or an altered pattern of uterine contractions during embryo transfer may be factors to consider in our attempt to solve this clinical issue. New diagnostics for assessing these conditions and new therapies to improve these dysfunctional situations are currently under investigation to be presumably included in the near future in the work-up of affected patients.

A Proteome Approach Reveals Differences between Fertile Women and Patients with Repeated Implantation Failure on Endometrial Level⁻Does hCG Render the Endometrium of RIF Patients?

Background: The molecular signature of endometrial receptivity still remains barely understood, especially when focused on the possible benefit of therapeutical interventions and implantation-related pathologies. Therefore, the protein composition of tissue and isolated primary cells (endometrial stromal cells, ESCs) from endometrial scratchings of ART (Assisted Reproductive Techniques) patients with repeated implantation failure (RIF) was compared to volunteers with proven fertility during the time of embryo implantation (LH + 7). Furthermore, an analysis of the endometrial tissue of fertile women infused with human chorionic gonadotropin (hCG) was conducted. Methods: Endometrial samples (n = 6 RIF, n = 10 fertile controls) were split into 3 pieces: 1/3 each was frozen in liquid nitrogen, 1/3 fixed in PFA and 1/3 cultured. Protein lysates prepared from fresh frozen tissue were processed for mass spectrometric analysis. Results: Three proteins (EPPK1, BCLAF1 and PTMA) showed a statistically altered abundance in the endometrial tissue of RIF patients. Furthermore, pathways like metabolism, immune system, ferroptosis and the endoplasmic reticulum were altered in RIF patients. Remarkably, endometrial tissues of RIF patients showed a significantly higher (p-value = 9 × 10⁻⁸) protein intensity correlation (Pearson’s correlation coefficient = 0.95) compared to fertile women (Pearson’s correlation coefficient = 0.88). The in vivo infusion of hCG stimulated proteins of endocytosis, HIF1 signalling and chemokine production. Notably, patients suffering from RIF had a clinical pregnancy rate of 19% after the intrauterine infusion of hCG before embryo transfer (ET) compared to their failed previous cycles. Conclusion: Our study showed for the first time that the endometrial proteome composition of RIF patients differs from fertile controls during the window of implantation. The intrauterine infusion of hCG prior to an embryo transfer might improve the chemokine triggered embryo-endometrial dialogue and intensify the angiogenesis and immune response. From a clinical point of view, the hCG infusion prior to an embryo transfer might increase the pregnancy rate of RIF patients.

Asynchronous and pathological windows of implantation: two causes of recurrent implantation failure

STUDY QUESTION

Is endometrial recurrent implantation failure (RIF) only a matter of an asynchronous (displaced) window of implantation (WOI), or could it also be a pathological (disrupted) WOI?

SUMMARY ANSWER

Our predictive results demonstrate that both displaced and disrupted WOIs exist and can present independently or together in the same RIF patient.

WHAT IS KNOWN ALREADY

Since 2002, many gene expression signatures associated with endometrial receptivity and RIF have been described. Endometrial transcriptomics prediction has been applied to the human WOI in two previous studies. One study describes endometrial RIF to be the result of a temporal displacement of the WOI. The other indicates that endometrial RIF can also result from a molecularly disrupted WOI without temporal displacement.

STUDY DESIGN, SIZE, DURATION

Retrospective analysis was undertaken to compare WOI endometrial transcriptomics predictions in controls (n = 72) and RIF patients (n = 43). RIF was clinically designated by the absence of implantation after four or more transfers of high quality embryos or after the placement of 10 or more embryos in multiple transfers. Endometrial tissue samples were collected from LH + 5 to LH + 8. We compared the two molecular causes of RIF to signatures currently described in the literature. We propose a new transcriptomic RIF taxonomy to fill the gap between the two hypotheses and to guide the development of clinical detection and determination of both types of RIF.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Utilizing 115 gene expression profiles, two different predictive designs were developed: one considering RIF versus controls removing menstrual cycle timing, called the disrupted or pathological model, and another stratifying the WOI in transcriptomic profiles related to timing for predicting displacements. The predictive value of each model was compared between all signatures selected. We propose a new genomic approach that distinguishes between both types of RIF in the same sample cohort.

MAIN RESULTS AND THE ROLE OF CHANCE

From the 16 signatures analysed, we clearly predicted two causes of RIF-both a displaced WOI and an on-time but pathologically disrupted WOI. A high predictive value related to WOI profiles associated with menstrual cycle timing was found in most of the signatures. Specifically, 69% of the signatures analysed presented an accuracy higher than expected by chance in a range from 0.87 to 0.97. Displacements and disruptions were not molecularly independent, as some signatures were moderately associated with both causes. The gene and functional comparison between signatures revealed that they were not similar, although we did find functions in common and a cluster of moderate functional concordance between some of the signatures that predicted displacements (the highest Cohen's Kappa index were between 0.55 and 0.62 depending on the functional database). We propose a new transcriptomic RIF taxonomy to fill the gap between these prior studies and to establish methodology for detecting and distinguishing both types of RIF in clinical practice. Our findings indicate these two phenotypes could present independently or together in the same RIF patient. RIF patients designated by clinical criteria have been stratified transcriptomically as 18.6% with only a displaced WOI, 53.5% with a displaced and pathological WOI, 23.3% with only a disrupted WOI, and 4.7% could be a clinical RIF with non-endometrial origin. The new RIF transcriptomic taxonomy avoids menstrual cycle timing as a confounding variable that should be controlled for, distinguishing clearly between a disrupted and a displaced WOI for precision medicine in RIF.

LIMITATIONS REASONS FOR CAUTION

The main objective of this study was to use transcriptomics to detect both RIF causes and to understand the role of transcriptomic signatures in these phenotypes. The predictive value in absolute terms for each signature was not indicative in these prediction designs; instead, the comparison between signatures was most important for prediction capability in the same sample cohort for both RIF causes. Clinical follow up of the RIF taxonomies proposed has not been analysed in this study, so further prospective clinical studies are necessary to determine the prevalence and penetrance of these phenotypes.

WIDER IMPLICATIONS OF THE FINDINGS

The main insight from this study is a new understanding of RIF taxonomy. Understanding how to classify RIF patients to distinguish clinically between a patient who could benefit from a personalized embryo transfer day and a patient with a disrupted WOI will enable identification and stratification for the research and development of new treatments. In addition, we demonstrate that basic research designs in endometrial transcriptomics cause masking of the study variable by the menstrual cycle timing.

STUDY FUNDING/COMPETING INTEREST(S)

This research has been funded by IVI-RMA; the authors do not have any competing interests.

Growth Hormone and Endometrial Receptivity

Administration of growth hormone (GH) during ovarian stimulation has shown beneficial effects on in vitro fertilization (IVF) outcomes. It is generally believed that this improvement is due to the stimulating effect of GH on oocyte quality. However, studies are emerging that show possible positive effect of GH administration on endometrial receptivity, thus suggesting an additional potential benefit at the level of the uterus, especially among women with recurrent implantation failure, thin endometrium, and older normal responders. This review summarizes recent data on GH co-treatment effects on endometrium and endometrial receptivity among infertile women undergoing IVF, and proposes possible mechanisms of GH actions in the endometrium.

Does endometrial scratching increase the rate of spontaneous conception in couples with unexplained infertility and a good prognosis (Hunault > 30%)? Study protocol of the SCRaTCH-OFO trial: a randomized controlled trial

Background

In the Netherlands, couples with unexplained infertility and a good prognosis to conceive spontaneously (i.e. Hunault > 30%) are advised to perform timed intercourse for at least another 6 months. If couples fail to conceive within this period, they will usually start assisted reproductive technology (ART). However, treatment of unexplained infertility by ART is empirical and can involve significant burdens. Intentional endometrial injury, also called ‘endometrial scratching’, has been proposed to positively affect the chance of embryo implantation in patients undergoing in vitro fertilization (IVF). It might also be beneficial for couples with unexplained infertility as defective endometrial receptivity may play a role in these women. The primary aim of this study is to determine whether endometrial scratching increases live birth rates in women with unexplained infertility.

Method

A multicentre randomized controlled trial will be conducted in Dutch academic and non-academic hospitals starting from November 2017. A total of 792 women with unexplained infertility and a good prognosis for spontaneous conception < 12 months (Hunault > 30%) will be included, of whom half will undergo endometrial scratching in the luteal phase of the natural cycle. The women in the control group will not undergo endometrial scratching. According to Dutch guidelines, both groups will subsequently perform timed intercourse for at least 6 months. The primary endpoint is cumulative live birth rate. Secondary endpoints are clinical and ongoing pregnancy rate; miscarriage rate; biochemical pregnancy loss; multiple pregnancy rate; time to pregnancy; progression to intrauterine insemination (IUI) or IVF; pregnancy complications; complications of endometrial scratching; costs and endometrial tissue parameters associated with reproductive success or failure. The follow-up duration is 12 months.

Discussion

Several small studies show a possible beneficial effect of endometrial scratching in women with unexplained infertility trying to conceive naturally or through IUI. However, the quality of this evidence is very low, making it unclear whether these women will truly benefit from this procedure. The SCRaTCH-OFO trial aims to investigate the effect of endometrial scratching on live birth rate in women with unexplained infertility and a good prognosis for spontaneous conception < 12 months.

Trial registration

NTR6687, registered August 31st, 2017.

Protocol version

Version 2.6, November 14th, 2018.

Endometrial stromal cell proteome mapping in repeated implantation failure and recurrent pregnancy loss cases and fertile women

RESEARCH QUESTION

Are there proteomic differences between endometrial stromal cells of repeated implantation failure (RIF), recurrent pregnancy loss (RPL) and normal fertile women, and is there differential protein expression upon decidualization?

DESIGN

This exploratory study investigated the proteome of in-vitro cultured endometrial stromal cells of women with RIF (n = 4), women with RPL (n = 3) and normal fertile women (n = 4), comparing day 0 with 5 days of decidualization. Total proteins extracted from cell lysates were analysed by high-definition mass spectrometry. Data analysis was performed using significance analysis of microarray in R (P < 0.05; false discovery rate [FDR] 10%).

RESULTS

In the RIF group, ANXA6, PSMC5 and FSCN1 were up-regulated (1.9-fold, 2.5-fold and 1.9-fold, respectively), whereas PBXIP1 was down-regulated (7.7-fold) upon decidualization. In the RPL group, RPS25 and ACADVL were down-regulated (1.9-fold and 2.4-fold, respectively; FDR 10%) between the non-decidualized and the decidualized samples. In the normal fertile group VIM and RPL23A were down-regulated (1.9-fold and 2.4-fold, respectively). Comparing ratios of expression of decidualized over non-decidualized samples in the different groups revealed six differentially expressed proteins: DUX4L2, CNPY4, PDE7A, CTSK, PCBP2 and PSMD4. Comparison of RPL versus normal fertile in the decidualized condition revealed serotransferrin to be differentially expressed. The changes in expression levels for serotransferrin, ANX6, ACDVL and VIM were confirmed by western blot.

CONCLUSIONS

Results show a varying response of endometrial stromal cells in distinct clinical groups (RIF, RPL and normal fertile) upon in-vitro decidualization. Serotransferrin could serve as a marker for the aberrant decidualization process in RPL.

Biomarkers in Fetomaternal Tolerance

Multiple mechanisms of tolerance operate in the immune cross-talk at the fetomaternal interface, contributing to successful pregnancy outcome. The cross-talk includes interaction between various cell subsets and between cytokines and molecules of the endocrine system. A depiction of how all these components interact with each other and contribute to tolerance of the fetus is not clearly understood. Dysregulation in one or more of these mechanisms leads to fetal loss. Few effective biomarkers are available that can safely predict fetal loss. This review discusses some potential biomarkers that can predict failure of tolerance at the fetomaternal interface.

Recurrent Implantation Failure-update overview on etiology, diagnosis, treatment and future directions

Recurrent implantation failure (RIF) refers to cases in which women have had three failed in vitro fertilization (IVF) attempts with good quality embryos. The definition should also take advanced maternal age and embryo stage into consideration. The failure of embryo implantation can be a consequence of uterine, male, or embryo factors, or the specific type of IVF protocol. These cases should be investigated to determine the most likely etiologies of the condition, as this is a complex problem with several variables. There are multiple risk factors for recurrent implantation failure including advanced maternal age, smoking status of both parents, elevated body mass index, and stress levels. Immunological factors such as cytokine levels and presence of specific autoantibodies should be examined, as well as any infectious organisms in the uterus leading to chronic endometritis. Uterine pathologies such as polyps and myomas as well as congenital anatomical anomalies should be ruled out. Sperm analysis, pre-implantation genetic screening and endometrial receptivity should be considered and evaluated, and IVF protocols should be tailored to specific patients or patient populations. Treatment approaches should be directed toward individual patient cases. In addition, we suggest considering a new initial step in approach to patients with RIF, individualized planned activities to activate the brain's reward system in attempt to improve immunological balance in the body.

A Two-Cohort RNA-seq Study Reveals Changes in Endometrial and Blood miRNome in Fertile and Infertile Women

The endometrium undergoes extensive changes to prepare for embryo implantation and microRNAs (miRNAs) have been described as playing a significant role in the regulation of endometrial receptivity. However, there is no consensus about the miRNAs involved in mid-secretory endometrial functions. We analysed the complete endometrial miRNome from early secretory (pre-receptive) and mid-secretory (receptive) phases from fertile women and from patients with recurrent implantation failure (RIF) to reveal differentially expressed (DE) miRNAs in the mid-secretory endometrium. Furthermore, we investigated whether the overall changes during early to mid-secretory phase transition and with RIF condition could be reflected in blood miRNA profiles. In total, 116 endometrial and 114 matched blood samples collected from two different population cohorts were subjected to small RNA sequencing. Among fertile women, 91 DE miRNAs were identified in the mid-secretory vs. early secretory endometrium, while no differences were found in the corresponding blood samples. The comparison of mid-secretory phase samples between fertile and infertile women revealed 21 DE miRNAs from the endometrium and one from blood samples. Among discovered novel miRNAs, chr2_4401 was validated and showed up-regulation in the mid-secretory endometrium. Besides novel findings, we confirmed the involvement of miR-30 and miR-200 family members in mid-secretory endometrial functions.