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Cell type-specific endometrial transcriptome analysis and uterine exosome communication: New approaches to decipher the embryo-maternal cross-talk during maternal recognition of pregnancy in the mare

English title Cell type-specific endometrial transcriptome analysis and uterine exosome communication: New approaches to decipher the embryo-maternal cross-talk during maternal recognition of pregnancy in the mare
Applicant Bauersachs Stefan
Number 173171
Funding scheme Project funding
Research institution AG Bauersachs Institut für Veterinär-Anatomie Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Animal Breeding
Start/End 01.03.2018 - 28.02.2022
Approved amount 496'000.00
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All Disciplines (8)

Discipline
Animal Breeding
Embryology, Developmental Biology
Molecular Biology
Veterinary Medicine
Cellular Biology, Cytology
Agricultural and Forestry Sciences
Physiology : other topics
Endocrinology

Keywords (13)

Equus caballus; Endometrosis; Endometrium; Proteomics; Extracellular vesicles/exosomes; RNA-Seq; Gene expression; MicroRNA; Uterus; Fertility; Embryo; Horse; Pregnancy

Lay Summary (German)

Lead
Untersuchung der Genexpression in verschiedenen Zelltypen der Gebärmutterschleimhaut der Stute und des Austauschs von Signalmolekülen über extra-zelluläre Vesikel in der Gebärmutter: Neue Ansätze zur Entzifferung der embryo-maternalen Kommunikation während der Phase der Erkennung der Trächtigkeit
Lay summary

Die Stute gehört zu den Säugetieren, die eine späte Implantation des Embryos in der Gebärmutter (Uterus) zeigen. Aus diesem Grund muss der Embryo seine Anwesenheit der Mutter vor der Implantation signalisieren. Daraufhin kann sich der Uterus auf die Implantation vorbereiten und die Entwicklung des Embryos entsprechend unterstützen. Diesen Prozess nennt man maternale Erkennung der Trächtigkeit. Bei der Stute tritt ein hoher Anteil an Trächtigkeitsverlusten während dieser Phase auf. Die bisherigen Erkenntnisse weisen darauf hin, dass eine fehlerhafte Kommunikation zwischen Embryo und Mutterstute oft die Ursache für diese Verluste ist.

Aus reproduktionsbiologischer Sicht ist die Stute aufgrund einer Reihe von einzigartigen Besonderheiten ein interessantes Untersuchungsmodell. So ist der Embryo zwischen Tag 7 und 23 von einer Glykoprotein-Kapsel umgeben, die ihm seine runde Form gibt. Zwischen Tag 6 und 16 bewegt sich der Embryo mehrmals täglich durch den gesamten Uterus, angetrieben durch Kontraktionen des Uterus. Trotz einer Vielzahl von Studien ist nach wie vor unklar, welche embryonalen und maternalen Signale für die Aufrechterhaltung der Gravidität beim Pferd verantwortlich sind.

Neben den sehr interessanten Aspekten in Bezug auf die Grundlagenforschung hat die Fertilität der Stute auch in ökonomischer Hinsicht Bedeutung. Nach einer erfolgreichen Karriere im Pferdesport werden viele Stuten erst im fortgeschrittenen Alter zur Zucht eingesetzt. Bei älteren Stuten treten gehäuft Trächtigkeitsverluste während der Phase der Erkennung der Trächtigkeit auf, was meist an einer degenerativen Veränderung der Gebärmutterschleimhaut (Endometrium) liegt.

In diesem Projekt werden neue Erkenntnisse zur embryo-maternalen Interaktion beim Pferd gewonnen mit dem Ziel, die zellulären und molekularen Mechanismen der embryo-maternalen Kommunikation in der Frühphase der Trächtigkeit besser zu verstehen sowie Biomarker für die Fertilität der Stute zu identifizieren.

Direct link to Lay Summary Last update: 15.02.2018

Responsible applicant and co-applicants

Employees

Project partner

Publications

Publication
Spatiotemporal endometrial transcriptome analysis revealed the luminal epithelium as key player during initial maternal recognition of pregnancy in the mare.
Rudolf Vegas Alba, Podico Giorgia, Canisso Igor F, Bollwein Heinrich, Almiñana Carmen, Bauersachs Stefan (2021), Spatiotemporal endometrial transcriptome analysis revealed the luminal epithelium as key player during initial maternal recognition of pregnancy in the mare., in Scientific Reports, 11(1), 22293-22293.
Isolation and Characterization of Equine Uterine Extracellular Vesicles: A Comparative Methodological Study
Almiñana Carmen, Rudolf Vegas Alba, Tekin Muhittin, Hassan Mubbashar, Uzbekov Rustem, Fröhlich Thomas, Bollwein Heinrich, Bauersachs Stefan (2021), Isolation and Characterization of Equine Uterine Extracellular Vesicles: A Comparative Methodological Study, in International Journal of Molecular Sciences, 22(2), 979-979.
Embryo–Maternal Interactions Underlying Reproduction in Mammals
Bauersachs Stefan, Almiñana Carmen (2020), Embryo–Maternal Interactions Underlying Reproduction in Mammals, 21(14), 4872-4872, MDPI, Basel 21(14), 4872-4872.
The Oviductal Extracellular Vesicles’ RNA Cargo Regulates the Bovine Embryonic Transcriptome
Bauersachs Stefan, Mermillod Pascal, Almiñana Carmen (2020), The Oviductal Extracellular Vesicles’ RNA Cargo Regulates the Bovine Embryonic Transcriptome, in International Journal of Molecular Sciences, 21(4), 1303-1303.
Extracellular vesicles: Multi-signal messengers in the gametes/embryo-oviduct cross-talk
Almiñana Carmen, Bauersachs Stefan (2020), Extracellular vesicles: Multi-signal messengers in the gametes/embryo-oviduct cross-talk, in Theriogenology.
Spatial organization of endometrial gene expression at the onset of embryo attachment in pigs
Zeng Shuqin, Ulbrich Susanne E., Bauersachs Stefan (2019), Spatial organization of endometrial gene expression at the onset of embryo attachment in pigs, in BMC Genomics, 20(1), 895-895.
Extracellular Vesicles in the Oviduct: Progress, Challenges and Implications for the Reproductive Success
Almiñana Carmen, Bauersachs Stefan (2019), Extracellular Vesicles in the Oviduct: Progress, Challenges and Implications for the Reproductive Success, in Bioengineering, 6(2), 32-32.
Cell type-specific endometrial transcriptome changes during initial recognition of pregnancy in the mare
Scaravaggi Iside, Borel Nicole, Romer Rebekka, Imboden Isabel, Ulbrich Susanne E., Zeng Shuqin, Bollwein Heinrich, Bauersachs Stefan (2019), Cell type-specific endometrial transcriptome changes during initial recognition of pregnancy in the mare, in Reproduction, Fertility and Development, 31(3), 496-496.

Datasets

Spatial organization of endometrial gene expression at the onset of embryo attachment in pigs

Author Zeng, Shuqin; Bick, Jochen; Ulbrich, Susanne E.; Bauersachs, Stefan
Publication date 29.10.2019
Persistent Identifier (PID) GSE123265
Repository NCBI Gene Expression Omnibus
Abstract
The aim of this present study was to characterize the complex transcriptome changes in different endometrial cell types during the preimplantation period for improving our understanding of localization of endometrial gene expression regulation in context of recognition of pregnancy. To do this analysis in a transcriptome-wide manner, RNA-seq was performed for samples derived from luminal epithelium (LE), glandular epithelium (GE), blood vessel (BV), and stroma (S) isolated by the use of LCM.Overall design: Four types of endometrial cells, luminal epithelial (LE), glandular epithelial (GE), blood vessel (BV), and stromal cells (S) were isolated by laser capture microdissection from endometria of Day 14 pregnant and cyclic control gilts (each group n=4), respectively, and then subjected to RNA-sequencing (RNA-Seq). The obtained datasets were compared to a RNA-Seq dataset from complete endometrial tissue samples collected in the same experiment.

Cell type-specific endometrial transcriptome changes in comparison of equine endometrium samples collected on Day 12 of pregnancy and Day 12 of the estrous cycle

Author Scaravaggi, Iside; Bauersachs, Stefan
Publication date 30.09.2018
Persistent Identifier (PID) GSE112236
Repository NCBI Gene Expression Omnibus
Abstract
The results of endometrial gene expression studies during the time of conceptus migration (Days 8 to 16) did not provide final conclusions on possible mechanisms of maternal recognition of pregnancy (MRP) in the mare. This finding called for the analysis of cell type-specific gene expression in the endometrium in response to the equine embryo, which could be the key for improved understanding of gene expression regulation in context of MRP. In a pilot study, we used laser capture microdissection (LCM) to collect samples of the luminal epithelium (LE), glandular epithelium (GE), and stroma from endometrial biopsies taken from five mares on Day 12 of pregnancy and Day 12 of the estrous cycle, respectively. RNA was isolated from the LCM samples in order to perform RNA sequencing. Data analysis showed that gene expression differences were greater between cell types than between pregnant and cyclic state. Differential gene expression between pregnant and cyclic state was mainly found in the LE but also in GE and stroma. The comparison with a previous RNA-Seq data set for whole biopsy samples derived from Day 12 of pregnancy revealed the specific origin of the observed gene expression differences. Furthermore, we found that a number of genes are specifically differentially expressed (DE) in only one cell type. Some genes not DE when looking at the whole biopsy were DE in one cell type and showed similar levels in the other cell types in comparison of pregnancy and cyclic stage. Overall, this study revealed new and important spatial information about endometrial gene expression during the phase of initial recognition of pregnancy in the mare. The results indicated induction of angiogenesis and blood vessel development by the presence of the conceptus, a specific spatial regulation of the immune system, spatial regulation of growth factors controlling cell differentiation and endometrial remodeling, and regulation of genes involved in production of prostaglandin (PG) precursors, PG transport, and PG receptors, specifically PTGFR in context of prevention of luteolysis. Furthermore, these results support our hypothesis of the existence of a specific response in different endometrial cell types in the mare and call for further studies.Overall design: Messenger RNA profiles of laser capture microdissection samples (luminal epithelium, glandular epithelium, stroma) from equine endometrial biopsies collected on Day 12 of pregnancy and Day 12 of estrous cycle, respectively, from in total 6 healthy mares were generated by RNA-sequencing using Illumina HiSeq 2500.

Effects of treatment with bovine oviductal extracellular vesicles on the transcriptome of bovine day 7 in vitro produced embryos

Author Almiñana, Carmen; Bauersachs, Stefan
Publication date 21.03.2020
Persistent Identifier (PID) GSE143596
Repository NCBI Gene Expression Omnibus
Abstract
Oviductal extracellular vesicles (oEVs) are emerging as key players in gamete/embryo-oviduct interactions contributing to successful pregnancy. Various positive effects of oEVs on gametes and early embryos have been found in vitro. To find out if these effects are associated with changes of embryonic gene expression, the embryonic transcriptome was analyzed after supplementation of bovine embryos with bovine oEVs during in vitro culture (IVC) in comparison to corresponding controls without oEVs. Embryos were cultured during 7 days of IVC with fresh oEVs, oEVs frozen after isolation from oviductal fluid or without oEVs (control), since a previous study showed different effects of fresh and frozen oEVs. Five pools of 10-14 embryos were analyzed for each group by low-input Illumina RNA-sequencing. Analysis of differential gene expression revealed 221 differentially expressed genes (DEGs) for the comparison of frozen oEVs vs control, 67 DEGs for fresh vs frozen oEVs, and only minor differences for the comparison fresh oEVs vs control (28 DEGs). An integrative analysis with the previously studied mRNA and small ncRNA content of bovine oEVs suggested direct effects of oEVs content on the embryonic transcriptome for the supplementation with frozen oEVs, i.e., increase of transcripts found in higher concentrations in oEVs and decrease of transcripts which are potential targets of miRNAs found in oEVs.Overall design Supplementation of bovine embryos during in vitro culture with fresh or frozen bovine oviductal EVs and untreated controls, low-input total RNA-seq of 5 replicates (pools of 8-14 embryos) per group using Illumina HiSeq 2500.

Isolation and characterization of equine uterine extracellular vesicles: a comparative methodological study

Author Fröhlich, Thomas
Publication date 09.09.2021
Persistent Identifier (PID) PXD022264
Repository PRIDE
Abstract
Extracellular vesicles (EVs) have been identified in the uterine fluid in different species and pointed as key players in the embryo-maternal dialogue, maternal recognition of pregnancy (MRP) and establishment of pregnancy. However, little is known about the uterine EVs in the mare. Therefore, the present study aimed at characterizing EVs from uterine lavage of cyclic mares by comparing five EVs isolation methods and the combination of them: (1) Ultracentrifugation (UC); (2) Concentration of lavage volume by Centricon ultrafiltration (CE); (3) the use of CE with different washing steps (PBS versus trehalose); (4) Size-exclusion chromatography with iZON-qEV columns to yield high-purity EVs and (5) a combination of the methods with best results based on EVs yield, purity, and protein cargo profiles. Transmission electron microscopy and Western blotting confirmed the isolation of EVs by all methods but with quantitative and qualitative differences. Mass spectrometry provided different protein profiles among methods with marked differences in the number of proteins and protein classes. Our results indicate that the combination of CE/trehalose/iZON/UC is an optimal method to isolate equine uterine EVs with good yield and purity that can be applied in future studies to determine the role of uterine EVs during MRP in the mare.

Spatiotemporal endometrial transcriptome analysis revealed the luminal epithelium as key player during initial maternal recognition of pregnancy in the mare

Author Rudolf Vegas, Alba; Podico, Giorgia; Canisso, Igor F.; Bollwein, Heinrich; Almiñana, Carmen; Bauersachs, Stefan
Publication date 16.12.2021
Persistent Identifier (PID) 10.1038/s41598-021-01785-3
Repository NCBI SRA
Abstract
AbstractDuring the period of maternal recognition of pregnancy (MRP) in the mare, the embryo needs to signal its presence to the endometrium to prevent regression of the corpus luteum and prepare for establishment of pregnancy. This is achieved by mechanical stimuli and release of various signaling molecules by the equine embryo while migrating through the uterus. We hypothesized that embryo’s signals induce changes in the endometrial gene expression in a highly cell type-specific manner. A spatiotemporal transcriptomics approach was applied combining laser capture microdissection and low-input-RNA sequencing of luminal and glandular epithelium (LE, GE), and stroma of biopsy samples collected from days 10-13 of pregnancy and the estrous cycle. Two comparisons were performed, samples derived from pregnancies with conceptuses ≥ 8 mm in diameter (comparison 1) and conceptuses ≤ 8 mm (comparison 2) versus samples from cyclic controls. The majority of gene expression changes was identified in LE and much lower numbers of differentially expressed genes (DEGs) in GE and stroma. While 1253 DEGs were found for LE in comparison 1, only 248 were found in comparison 2. Data mining mainly focused on DEGs in LE and revealed regulation of genes related to prostaglandin transport, metabolism, and signaling, as well as transcription factor families that could be involved in MRP. In comparison to other mammalian species, differences in regulation of genes involved in epithelial barrier formation and conceptus attachment and implantation reflected the unique features of equine reproduction at the time of MRP at the molecular level.

Transcriptomics of equine uterine extracellular vesicles

Author Bauersachs, Stefan
Publication date 18.03.2022
Persistent Identifier (PID) PRJNA817576
Repository NCBI SRA
Abstract
In contrast to other domestic mammals, the embryo-derived signal(s) leading to maternal recognition of pregnancy (MRP) are still unknow in the mare. We hypothesize that these signals could be packed into uterine extracellular vesicles (uEVs), acting as multi-signal messengers between the conceptus and the maternal tract and contributing to MRP. To unveil these signals, the RNA and protein cargos of uEVs isolated from uterine lavages collected from pregnant mares (P; day 10, 11, 12 and 13 after ovulation) and cyclic control mares (C; day 10 and 13 after ovulation) were analyzed. Our results showed a fine-tuned regulation of the uEV cargo (RNAs and proteins), by the day of pregnancy, the estrous cycle, and even the size of the embryo. A particular RNA pattern was identified with specific increase on P12 related to immune system and hormonal response. Besides, a set of proteins as well as RNAs was highly enriched in EVs on P12 and P13. Differential abundance of miRNAs was also identified in P13-derived uEVs. Their target genes were linked to down- or upregulated genes in the embryo and the endometrium, exposing their potential origin. Our study identified for the first time specific molecules packed in uEVs, which were previously associated to MRP in the mare, and thus bringing added value to the current knowledge. Further integrative and functional analyses will help to confirm the role of these molecules in uEVs during MRP in the mare.

Collaboration

Group / person Country
Types of collaboration
Prof. Igor Canisso, Theriogenology, College of Veterinary Medicine, University of Illinois United States of America (North America)
- Research Infrastructure
- Exchange of personnel
Prof. Rustem Uzbekov, Département des Microscopies, Faculté de Médecine, University of Tours France (Europe)
- Research Infrastructure
Prof. Nicole Borel, Institut für Veterinärpathologie Vetsuisse-Fakultät Universität Zürich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Dr. Pascal Mermillod, INRA Centre Val de Loire France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dr. Thomas Fröhlich, LAFUGA Proteomics, Gene Center, LMU Munich Germany (Europe)
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Society for the Study of Reproduction 54th Annual Meeting Poster Spatiotemporal endometrial transcriptome analysis revealed the luminal epithelium as key player during initial maternal recognition of pregnancy in the mare 13.12.2021 St. Louis, United States of America Bollwein Heinrich; Rudolf Vegas Alba; Almiñana Brines Carmen; Bauersachs Stefan;
Academic conferences on challenges and advances of animal reproduction and production on modern livestock Individual talk Exosomas/vesículas extracellulares en reproducción: nanomensajeros en la comunicación entre gametos/embriones y el tracto maternal 17.11.2021 Universidad Coperativa de Colombia, Colombia Almiñana Brines Carmen;
Swiss Animal Breeding Technology Platform (SABRE-TP), Workshop 2021 Talk given at a conference Overview of ongoing projects 10.11.2021 Zürich, Switzerland Bauersachs Stefan;
Zweite AgroVet-Strickhof Tagung Poster Are the uterine extracellular vesicles key players in embryo-maternal interactions in the mare? 27.10.2021 Lindau Eschikon, Switzerland Bollwein Heinrich; Bauersachs Stefan; Rudolf Vegas Alba; Almiñana Brines Carmen;
Zweite AgroVet-Strickhof Tagung Poster The endometrial luminal epithelium shows the main response to conceptus signals during the period of maternal recognition of pregnancy in the mare 27.10.2021 Lindau Eschikon, Switzerland Almiñana Brines Carmen; Rudolf Vegas Alba; Bollwein Heinrich; Bauersachs Stefan;
54th Annual Conference Physiology and Pathology of Reproduction and simultaneously 46th Joint Congress of Veterinary and Human Medicine Talk given at a conference Cell type-specific response of the endometrium of pregnant mares to the presence of an embryo during the period of maternal recognition of pregnancy: a spatial transcriptomic analysis 10.02.2021 Zurich, online event, Switzerland Almiñana Brines Carmen; Bauersachs Stefan; Rudolf Vegas Alba; Bollwein Heinrich;
54th Annual Conference Physiology and Pathology of Reproduction and simultaneously 46th Joint Congress of Veterinary and Human Medicine Poster Equine uterine extracellular vesicles isolation and characterization: a comparative study to-wards the best strategy 10.02.2021 Zurich, online event, Switzerland Bollwein Heinrich; Bauersachs Stefan; Rudolf Vegas Alba; Almiñana Brines Carmen;
54th Annual Conference Physiology and Pathology of Reproduction and simultaneously 46th Joint Congress of Veterinary and Human Medicine Poster Identification of extracellular vesicles in blastocoel fluid of in vitro produced bovine embryos 10.02.2021 Zurich, online event, Switzerland Almiñana Brines Carmen; Bollwein Heinrich;
54th Annual Conference Physiology and Pathology of Reproduction and simultaneously 46th Joint Congress of Veterinary and Human Medicine Poster Isolation of extracellular vesicles from the bovine caruncle 10.02.2021 Zurich, online event, Switzerland Almiñana Brines Carmen;
GCB Symposium 2021 Graduate School for Cellular and Biomedical Sciences Poster Does the Equine Conceptus Has the Ability to Modulate the Different Endometrial Cell Types During the Time of Maternal Recognition of Pregnancy in the Mare? 28.01.2021 Bern, online event, Switzerland Rudolf Vegas Alba; Almiñana Brines Carmen; Bollwein Heinrich; Bauersachs Stefan;
Programa de Seminarios Internacionales 2020 del programa de Doctorado en Ciencias Veterinarias de la Universidad de Concepción Individual talk Descifrando el diálogo materno-embrionario en el oviducto: Interceptando los nanomensajes mediante vesículas extracelulares 09.12.2020 Universidad de Concepción, Chile, Chile Almiñana Brines Carmen;
3rd Poster & Networking Day of the Vetsuisse Faculty Zurich Poster Cell type-specific endometrial gene expression analysis during the period of maternal recognition of pregnancy in the mare 02.12.2020 Zurich, online event, Switzerland Bauersachs Stefan; Almiñana Brines Carmen; Rudolf Vegas Alba;
3rd Poster & Networking Day of the Vetsuisse Faculty Zurich Poster Isolation and characterization of equine uterine extracellular vesicles: a comparative meth-odological study 02.12.2020 Zurich, online event, Switzerland Bollwein Heinrich; Bauersachs Stefan; Almiñana Brines Carmen; Rudolf Vegas Alba;
19th International Congress on Animal Reproduction Poster Isolation and characterization of uterine extracellular vesicles from cyclic mares 28.06.2020 Bologna, Italy Bollwein Heinrich; Almiñana Brines Carmen; Bauersachs Stefan; Rudolf Vegas Alba;
15. Jahrestagung „Netzwerk Pferdeforschung Schweiz“ Poster Analyse der Zelltyp-spezifischen Genexpression im Endometrium während der initialen Erkennung der Trächtigkeit bei der Stute 02.04.2020 Avenche, Switzerland Rudolf Vegas Alba; Bollwein Heinrich; Almiñana Brines Carmen; Bauersachs Stefan;
GCB Symposium 2020 Graduate School for Cellular and Biomedical Sciences Poster Cell type-specific gene expression analysis during the period of maternal recognition of pregnancy in the mare 30.01.2020 Bern, Switzerland Bauersachs Stefan;
Gynäkologisch-Endokrinologisches Kolloquium, Herbst-/Wintersemester 2019/2020, Klinik für Reproduktions-Endokrinologie, USZ Individual talk Extracellular vesicles: key messengers in the gamete/embryo oviductal cross-talk 05.12.2019 Zürich, Switzerland Almiñana Brines Carmen;
Antrittsvorlesung Universität Zürich Individual talk Functional genomics in animal reproduction – revealing molecular signatures of fertility in mammals 02.12.2019 Zürich, Switzerland Bauersachs Stefan;
46. AET-d Jahrestagung Talk given at a conference Entschlusselung der embryo-maternalen Interaktion bei der Stute 04.07.2019 Wülflingen, Switzerland Bauersachs Stefan;
1. AgroVet-Strickhof Tagung Talk given at a conference Cell type-specific endometrial transcriptome analysis and uterine exosome communication: New approaches to decipher the embryo-maternal cross-talk during maternal recognition of pregnancy in the mare 01.07.2019 Lindau, Switzerland Bauersachs Stefan;
Schweizerische Vereinigung für Tierwissenschaften, Swiss Animal Breeding Technology Platform (SABRE-TP) Workshop Talk given at a conference Transcriptomics and reproduction – revealing molecular signatures of fertility in mammals 05.06.2019 Zürich, Switzerland Bauersachs Stefan;
52nd Annual Con-ference of Physiology and Pathology of Reproduction Talk given at a conference Spatiotemporal gene expression in porcine endometrium at the time of recognition of pregnancy and the onset of conceptus attachment 20.02.2019 Göttingen, Germany Bauersachs Stefan;
Annual Conference of the International Embryo Technology Society Poster Spatial analysis of transcriptome changes in porcine endome-trium on Day 14 of pregnancy 20.01.2019 New Orleans, United States of America Bauersachs Stefan;
1st Poster and Networking Day of the Vetsuisse Faculty Zürich Poster Deciphering maternal recognition of pregnancy in the mare 05.12.2018 Zürich, Switzerland Bauersachs Stefan; Almiñana Brines Carmen;
ESHRE CAMPUS 2018 "The luteal phase: the neglected part of assisted reproduction?" Talk given at a conference The luteal phase in close relatives to the human: lessons to be learned from animal reproduction 25.05.2018 Hamburg, Germany Bauersachs Stefan;


Awards

Title Year
Guest Editors Special Issue "Embryo-Maternal Interactions Underlying Reproduction in Mammals" in International Journal of Molecular Sciences 2019

Associated projects

Number Title Start Funding scheme
200534 The uterine MICRObiota and FERTility in the mare: Why the bacterial composition matters? - MICROFERT 01.07.2021 Project funding

Abstract

Embryo maternal communication and successful recognition of pregnancy is vital for establishment of pregnancy in the horse, as well as in many other mammalian species. The mare has a number of unique aspects of pregnancy, e.g., a glycoprotein capsule enveloping the embryo between Days 7 and 21, the constant migration of the conceptus throughout the uterus during the phase of initial maternal recognition of pregnancy (MRP), and the long phase prior to placentation. In contrast to other ungulates where the embryonic pregnancy recognition signal has been identified, the signal for MRP in equids is still unknown and the nature of embryo-maternal communication is only partially understood. Therefore, the proposed study will apply a combination of new approaches to unravel mechanisms of embryo-maternal interactions during initial MRP to prevent regression of the corpus luteum and to investigate disturbed endometrial functions by comparing fertile and subfertile mares. These approaches include: i) analysis of cell type-specific endometrial gene expression and ii) analysis of uterine exosomes and proteins in the uterine fluid.In the first study of the project, samples will be collected during the time of initial MRP (Day 13), including endometrial biopsies, uterine fluid, and embryos. We hypothesize that gene expression in specific endometrial cell types and uterine secretions are changing due to the presence of the embryo and a mechanical stimulus. Luminal and glandular epithelium, blood vessels, and stromal areas will be isolated from endometrial biopsies collected from pregnant mares, the corresponding cyclic stage, and mares who received a silicone sphere to mimic mechanical signaling of the embryo. Furthermore, the uterine fluid (UF) containing extracellular vesicles (EVs)/exosomes and the embryo will be studied. The information about localization of observed gene expression changes in specific endometrial cells is facilitating specific interpretation of signaling pathways and will provide information about potential interactions between different endometrial cell types. The analysis of the UF will allow the identification of important molecules exchanged between the embryo and uterus. The analysis of exosomes is of particular importance since they contain proteins, lipids and nucleic acids (DNA, RNA) that can be transferred to recipient cells as a new way of cell-to-cell communication but also can exert a functional effect on the target cells, i.e. the conceptus. Moreover, the exosomes content is a reflection of the physiological and pathological conditions of the cells of origin, which make them promising diagnostic and therapeutic tools. Analysis of exosome content at the mRNA and small RNA level, including miRNA will provide information about possible mechanisms of MRP. A proteomic analysis of the uterine fluid (UF) will be performed, while EVs/exosomes will be analyzed at protein, mRNA and miRNA level. Moreover, transcriptome analysis of the obtained embryos will complete the analysis of embryo-maternal interaction during the time of MRP.In the second study, samples will be collected from mares with pathological changes of the endometrium (endometrosis), the main cause of subfertility and infertility, particularly in older mares. Many mares develop an endometrosis, a fibrotic alteration mainly affecting the uterine glands. The cell type-specific endometrial gene expression analysis will determine the cell types showing the greatest alterations associated with endometrosis. Furthermore, the analysis of EVs/exosomes and proteins in the uterine fluid will show the effects of fibrotic alterations in the endometrium on uterine secretions. Altogether, this approach will uncover signaling pathways and biological processes which are influenced by these pathological alterations.The projected investigations of embryo-maternal interactions in the mare will i) provide a basis for a better understanding of the mechanisms of initial MRP in the horse, ii) determine effects of pathological changes in the endometrium associated with decreased fertility on embryo-maternal cross-talk, thereby giving insights into the causes of early embryonic losses, and iii) deliver uterine biomarkers related to female fertility based on the uterine exosomal content.
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