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

Abstract 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.

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Differential MicroRNA Expression Involved in Endometrial Receptivity of Goats

Biomolecules ◽

10.3390/biom11030472 ◽

2021 ◽

Vol 11 (3) ◽

pp. 472

Author(s):

Xupeng Zang ◽

Chen Zhou ◽

Wenjing Wang ◽

Jianyu Gan ◽

Yaokun Li ◽

...

Keyword(s):

Molecular Mechanisms ◽

High Throughput Sequencing ◽

Target Genes ◽

Expression Profiles ◽

Embryo Implantation ◽

Endometrial Receptivity ◽

Fish Analysis ◽

Factors Affecting ◽

Mirna Expression Profiles ◽

Differentially Expressed Mirnas

Endometrial receptivity represents one of the leading factors affecting the successful implantation of embryos during early pregnancy. However, the mechanism of microRNAs (miRNAs) to establish goat endometrial receptivity remains unclear. This study was intended to identify potential miRNAs and regulatory mechanisms associated with establishing endometrial receptivity through integrating bioinformatics analysis and experimental verification. MiRNA expression profiles were obtained by high-throughput sequencing, resulting in the detection of 33 differentially expressed miRNAs (DEMs), followed by their validation through quantitative RT-PCR. Furthermore, 10 potential transcription factors (TFs) and 1316 target genes of these DEMs were obtained, and the TF–miRNA and miRNA–mRNA interaction networks were constructed. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that these miRNAs were significantly linked to establishing endometrial receptivity. Moreover, the fluorescence in situ hybridization (FISH) analysis, dual-luciferase report assay, and immunohistochemistry (IHC) analysis corroborated that chi-miR-483 could directly bind to deltex E3 ubiquitin ligase 3L (DTX3L) to reduce its expression level. In conclusion, our findings contribute to a better understanding of molecular mechanisms regulating the endometrial receptivity of goats, and they provide a reference for improving embryo implantation efficiency.

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Current studies on human implantation: a brief overview

Reproduction Fertility and Development ◽

10.1071/rd9951395 ◽

1995 ◽

Vol 7 (6) ◽

pp. 1395 ◽

Cited By ~ 11

Author(s):

PA Rogers

Keyword(s):

Animal Models ◽

Embryo Implantation ◽

Endometrial Receptivity ◽

Biochemical Changes ◽

Human Studies ◽

Complex Interactions ◽

Complex Process ◽

Wide Range ◽

Human Implantation

Embryo implantation involves a series of complex interactions between the developing embryo and the maternal endometrium. Results of studies with animal models suggest that the uterus must undergo a series of morphological and biochemical changes, mediated primarily by oestrogen and progesterone, before it becomes receptive for successful implantation. At present there is little understanding of the endometrial changes required to achieve endometrial receptivity for implantation in the human. It appears that control of receptivity is not as stringent in the human as in some other species, with IVF data suggesting that the duration of receptivity is at least 4 days, and that successful implantation can occur under a relatively wide range of morphological and ultrastructural conditions. Research on the later stages of implantation, including embryo positioning within the uterus, attachment and invasion, has been almost non-existent in the human. Further studies are critical for a better understanding of this complex process, although human studies will always be limited by ethical constraints.

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90 YEARS OF PROGESTERONE: New insights into progesterone receptor signaling in the endometrium required for embryo implantation

Journal of Molecular Endocrinology ◽

10.1530/jme-19-0212 ◽

2020 ◽

Vol 65 (1) ◽

pp. T1-T14 ◽

Cited By ~ 1

Author(s):

Francesco J DeMayo ◽

John P Lydon

Keyword(s):

Progesterone Receptor ◽

Nuclear Receptor ◽

Molecular Mechanisms ◽

Embryo Implantation ◽

Endometrial Receptivity ◽

Crystalline Form ◽

Functional Connection ◽

Genome Wide ◽

Molecular Landscape ◽

Selection Of

Progesterone’s ability to maintain pregnancy in eutherian mammals highlighted this steroid as the ‘hormone of pregnancy’. It was the unique ‘pro-gestational’ bioactivity of progesterone that enabled eventual purification of this ovarian steroid to crystalline form by Willard Myron Allen in the early 1930s. While a functional connection between normal progesterone responses (’progestational proliferation’) of the uterus with the maintenance of pregnancy was quickly appreciated, an understanding of progesterone’s involvement in the early stages of pregnancy establishment was comparatively less well understood. With the aforementioned as historical backdrop, this review focuses on a selection of key advances in our understanding of the molecular mechanisms by which progesterone, through its nuclear receptor (the progesterone receptor), drives the development of endometrial receptivity, a transient uterine state that allows for embryo implantation and the establishment of pregnancy. Highlighted in this review are the significant contributions of advanced mouse engineering and genome-wide transcriptomic and cistromic analytics which reveal the pivotal molecular mediators and modifiers that are essential to progesterone-dependent endometrial receptivity and decidualization. With a clearer understanding of the molecular landscape that underpins uterine responsiveness to progesterone during the periimplantation period, we predict that common gynecologic morbidities due to abnormal progesterone responsiveness will be more effectively diagnosed and/or treated in the future.

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Progesterone and Estrogen Signaling in the Endometrium: What Goes Wrong in Endometriosis?

International Journal of Molecular Sciences ◽

10.3390/ijms20153822 ◽

2019 ◽

Vol 20 (15) ◽

pp. 3822 ◽

Cited By ~ 33

Author(s):

Ryan M. Marquardt ◽

Tae Hoon Kim ◽

Jung-Ho Shin ◽

Jae-Wook Jeong

Keyword(s):

Pelvic Pain ◽

Large Scale ◽

Molecular Mechanisms ◽

Embryo Implantation ◽

Uterine Cavity ◽

Endometrial Receptivity ◽

Estrogen Signaling ◽

Normal Menstrual Cycle ◽

Hormone Imbalance ◽

Dynamic Interplay

In the healthy endometrium, progesterone and estrogen signaling coordinate in a tightly regulated, dynamic interplay to drive a normal menstrual cycle and promote an embryo-receptive state to allow implantation during the window of receptivity. It is well-established that progesterone and estrogen act primarily through their cognate receptors to set off cascades of signaling pathways and enact large-scale gene expression programs. In endometriosis, when endometrial tissue grows outside the uterine cavity, progesterone and estrogen signaling are disrupted, commonly resulting in progesterone resistance and estrogen dominance. This hormone imbalance leads to heightened inflammation and may also increase the pelvic pain of the disease and decrease endometrial receptivity to embryo implantation. This review focuses on the molecular mechanisms governing progesterone and estrogen signaling supporting endometrial function and how they become dysregulated in endometriosis. Understanding how these mechanisms contribute to the pelvic pain and infertility associated with endometriosis will open new avenues of targeted medical therapies to give relief to the millions of women suffering its effects.

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Lipoxins: A Novel Regulator in Embryo Implantation

The Scientific World JOURNAL ◽

10.1100/tsw.2011.15 ◽

2011 ◽

Vol 11 ◽

pp. 235-241 ◽

Cited By ~ 7

Author(s):

Jing Xiong ◽

Pan Zeng ◽

Duyun Ye

Keyword(s):

Cross Talk ◽

Leukemia Inhibitory Factor ◽

Molecular Mechanisms ◽

Embryo Implantation ◽

Endometrial Receptivity ◽

Inhibitory Factor ◽

Resolution Of Inflammation ◽

Recent Advances ◽

Close Relationship

Embryo implantation is essential for mammalian pregnancy, which involves intricate cross-talk between the blastocyst and the maternal endometrium. Recent advances have identified various molecules crucial to implantation and endometrial receptivity, including leukemia inhibitory factor, calcitonin, and homeobox A10. There is a close relationship between implantation and inflammation. Lipoxins, important in the resolution of inflammation, may be a potential regulator in implantation. Here we discuss the hypothesis that lipoxins may work as a novel regulator in embryo implantation and the possible molecular mechanisms.

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Role of adipokines in embryo implantation

Endocrine Connections ◽

10.1530/ec-21-0288 ◽

2021 ◽

Author(s):

Davoud Jafari-Gharabaghlou ◽

Mostafa Vaghari-Tabari ◽

Hajar Oghbaei ◽

Laura Lotz ◽

Reza Zarezadeh ◽

...

Keyword(s):

Early Pregnancy ◽

Molecular Mechanisms ◽

Embryo Implantation ◽

Endometrial Receptivity ◽

Complex Process ◽

Strict Regulation ◽

Implantation Process ◽

Maternal Fetal Transmission ◽

Multiple Molecules

Embryo implantation is a complex process in which multiple molecules acting together under strict regulation. Studies showed the production of various adipokines and their receptors in the embryo and uterus, where they can influence the maternal-fetal transmission of metabolites and embryo implantation. Therefore, these cytokines have opened a novel area of study in the field of embryo-maternal cross-talk during early pregnancy. In this respect, the involvement of adipokines has been widely reported in the regulation of both physiological and pathological aspects of the implantation process. However, the information about the role of some recently identified adipokines is limited. This review aims to highlight the role of various adipokines in embryo-maternal interactions, endometrial receptivity, and embryo implantation, as well as the underlying molecular mechanisms.

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Small non-coding RNAs in embryonic pre-implantation

Current Molecular Medicine ◽

10.2174/1566524021666210526162917 ◽

2021 ◽

Vol 21 ◽

Author(s):

Hamid Nazarian ◽

Marefat Ghaffari Novin ◽

Sara Khaleghi ◽

Bahare Habibi

Keyword(s):

Assisted Reproduction ◽

Embryo Implantation ◽

Mechanical Damage ◽

Endometrial Receptivity ◽

Embryo Viability ◽

Non Invasive ◽

New Information ◽

Extracellular Mirnas ◽

Extracellular Environment ◽

Multiple Molecules

Failure of embryo implantation has been introduced as an important limiting parameter in early assisted reproduction and pregnancy. The embryo-maternal interactions, endometrial receptivity, and detections of implantation consist of the embryo viability. For regulating the implantation, multiple molecules may be consisted, however, their specific regulatory mechanisms still stand unclear. MicroRNAs (miRNAs) have been highly concerned due to their important effect on human embryo implantation. MicroRNA (miRNA), which acts as the transcriptional regulator of gene expression, is consisted in embryo implantation. Scholars determined that miRNAs cannot affect the cells and release by cells in the extracellular environment considering facilitating intercellular communication, multiple packaging forms, and preparing indicative data in the case of pathological and physiological conditions. The detection of extracellular miRNAs provided new information in cases of implantation studies. For embryo-maternal communication, MiRNAs offered novel approaches. In addition, in assisted reproduction, for embryo choice and prediction of endometrial receptivity, they can act as non-invasive biomarkers and can enhance the accuracy in the process of reducing the mechanical damage for the tissue.

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Modulation of the Immune Response by Deferasirox in Myelodysplastic Syndrome Patients

Pharmaceuticals ◽

10.3390/ph14010041 ◽

2021 ◽

Vol 14 (1) ◽

pp. 41

Author(s):

Hana Votavova ◽

Zuzana Urbanova ◽

David Kundrat ◽

Michaela Dostalova Merkerova ◽

Martin Vostry ◽

...

Keyword(s):

Gene Expression ◽

Immune Response ◽

Blood Cell ◽

Myelodysplastic Syndrome ◽

Molecular Mechanisms ◽

Expression Profiles ◽

Adaptive Immune Response ◽

Gene Expression Profiles ◽

Iron Chelator ◽

Multiple Cancer

Deferasirox (DFX) is an oral iron chelator used to reduce iron overload (IO) caused by frequent blood cell transfusions in anemic myelodysplastic syndrome (MDS) patients. To study the molecular mechanisms by which DFX improves outcome in MDS, we analyzed the global gene expression in untreated MDS patients and those who were given DFX treatment. The gene expression profiles of bone marrow CD34+ cells were assessed by whole-genome microarrays. Initially, differentially expressed genes (DEGs) were determined between patients with normal ferritin levels and those with IO to address the effect of excessive iron on cellular pathways. These DEGs were annotated to Gene Ontology terms associated with cell cycle, apoptosis, adaptive immune response and protein folding and were enriched in cancer-related pathways. The deregulation of multiple cancer pathways in iron-overloaded patients suggests that IO is a cofactor favoring the progression of MDS. The DEGs between patients with IO and those treated with DFX were involved predominantly in biological processes related to the immune response and inflammation. These data indicate DFX modulates the immune response mainly via neutrophil-related genes. Suppression of negative regulators of blood cell differentiation essential for cell maturation and upregulation of heme metabolism observed in DFX-treated patients may contribute to the hematopoietic improvement.

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In-depth transcriptomic analysis of human retina reveals molecular mechanisms underlying diabetic retinopathy

Scientific Reports ◽

10.1038/s41598-021-88698-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kolja Becker ◽

Holger Klein ◽

Eric Simon ◽

Coralie Viollet ◽

Christian Haslinger ◽

...

Keyword(s):

Diabetic Retinopathy ◽

Rna Sequencing ◽

Molecular Mechanisms ◽

Vision Loss ◽

Ganglion Cells ◽

Expression Profiles ◽

Cell Types ◽

Sequencing Data ◽

Disease Stages ◽

Post Transcriptional Regulation

AbstractDiabetic Retinopathy (DR) is among the major global causes for vision loss. With the rise in diabetes prevalence, an increase in DR incidence is expected. Current understanding of both the molecular etiology and pathways involved in the initiation and progression of DR is limited. Via RNA-Sequencing, we analyzed mRNA and miRNA expression profiles of 80 human post-mortem retinal samples from 43 patients diagnosed with various stages of DR. We found differentially expressed transcripts to be predominantly associated with late stage DR and pathways such as hippo and gap junction signaling. A multivariate regression model identified transcripts with progressive changes throughout disease stages, which in turn displayed significant overlap with sphingolipid and cGMP–PKG signaling. Combined analysis of miRNA and mRNA expression further uncovered disease-relevant miRNA/mRNA associations as potential mechanisms of post-transcriptional regulation. Finally, integrating human retinal single cell RNA-Sequencing data revealed a continuous loss of retinal ganglion cells, and Müller cell mediated changes in histidine and β-alanine signaling. While previously considered primarily a vascular disease, attention in DR has shifted to additional mechanisms and cell-types. Our findings offer an unprecedented and unbiased insight into molecular pathways and cell-specific changes in the development of DR, and provide potential avenues for future therapeutic intervention.

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Endometrial Perivascular Progenitor Cells and Uterus Regeneration

Journal of Personalized Medicine ◽

10.3390/jpm11060477 ◽

2021 ◽

Vol 11 (6) ◽

pp. 477

Author(s):

Shiyuan Li ◽

Lijun Ding

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

Embryo Implantation ◽

Endometrial Receptivity ◽

Perivascular Cells ◽

Asherman’S Syndrome ◽

Outermost Layer ◽

Adventitial Cells ◽

Structure And Functions ◽

Large Vessels

Ovarian steroid-regulated cyclical regeneration of the endometrium is crucial for endometrial receptivity and embryo implantation, and it is dependent on the dynamic remodeling of the endometrial vasculature. Perivascular cells, including pericytes surrounding capillaries and microvessels and adventitial cells located in the outermost layer of large vessels, show properties of mesenchymal stem cells, and they are thus promising candidates for uterine regeneration. In this review, we discuss the structure and functions of the endometrial blood vasculature and their roles in endometrial regeneration, the main biomarkers and characteristics of perivascular cells in the endometrium, and stem cell-based angiogenetic therapy for Asherman’s syndrome.

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