Biology of Reproduction

In vitro fertilization (IVF) is a non-coital method of conception used to treat human infertility. Although IVF is viewed as largely safe, it is associated with adverse outcomes in the fetus, placenta, and adult offspring life. Because studies focusing on the effect of IVF on the male reproductive system are limited, we used a mouse model to assess the morphological and molecular effects of IVF on male offspring. We evaluated three developmental stages: 18.5-day fetuses and 12- and 39-week-old adults. Regardless of age, we observed changes in testicular-to-body weight ratios, serum testosterone levels, testicular morphology, gene expression, and DNA methylation. Also, sperm showed changes in morphology and DNA methylation. To assess multigenerational phenotypes, we mated IVF and naturally conceived males with wild-type females. Offspring from IVF males exhibited decreased fetal weight-to-placental weight ratios and changes in placenta morphology regardless of sex. At 12-weeks-of-age, offspring showed higher body weights and differences in glucose, triglycerides, insulin, total cholesterol, HDL and LDL/VLDL levels. Both sexes showed changes in gene expression in liver, testes and ovaries, and decreased global DNA methylation. Collectively, our findings demonstrate that male IVF offspring exhibit abnormal testicular and sperm morphology and molecular alterations and transmit defects multigenerationally.

The oviduct comprises 4 main regions: infundibulum (oocyte pick-up), ampulla (fertilization), isthmus (sperm capacitation and reservoir, preimplantation embryonic development), and uterotubal junction (UTJ; sperm and embryo transport). Mounting evidence in livestock and rodents suggest that gametes alter gene expression in secretory and ciliated epithelial cells of the oviduct. To elucidate whether adaptive interactions between the oviduct and gamete/embryo exist, we performed bulk RNA-sequencing on oviductal tissues collected from infundibulum+ampulla (IA) or isthmus+UTJ (IU) at various developmental stages (0.5, 1.5, 2.5-, and 3.5-days post coitus (dpc)) in mice. Samples were also collected during days 0.5, 1.5, 2.5, and 3.5 of pseudopregnancy (dpp). We found a strong region (IA vs. IU)-specific expression of large clusters of genes. The transition from 0.5 dpc to other pregnancy timepoints induces large sets of differentially expressed genes (DEGs) in pregnancy and pseudopregnancy in both IA and IU regions. Specifically, genes involved in pro-inflammatory responses were detected in both IU and IA regions. The presence of sperm at 0.5 dpc induces DEGs involved in pro-inflammatory responses in the IU region with an enrichment of biological processes for inflammatory cytokines, macrophage, and neutrophil recruitment. Additionally, DEGs are enriched in mitogen-activated protein kinase (MAPK) pathways along with genes in the Dusp family, Map3k8, Il1b, and Il1r2, among others. However, at 1.5 dpc we observed a strong shift to an anti-inflammatory condition in the IU region. These observations were absent in 0.5 and 1.5 dpp, suggesting that the DEGs observed for those inflammatory responses during pregnancy were likely induced by the presence of sperm. scRNA-seq analysis revealed that the inflammatory responsive genes were likely produced by secretory epithelial cells, compared to other cell types in the oviduct. In addition, multiple DEGs involved in pyruvate and glycolysis were enriched in the IU region, which could provide metabolic support for developing embryos. Lastly, we have also identified that there were cells that express immune markers in the oviduct, indicating that the oviduct is an immuno-dynamic tissue. In conclusion, our findings indicate that the oviduct is adaptive and responsive to the presence of sperm and embryos in a spatiotemporal manner. In this report, we intend to disseminate our findings on the transcriptional profiles during different stages of pregnancy. The complete study and validation at the protein level are currently underway and will be updated as soon as the data are available.

We tested the hypothesis that a panel of placental mammal-specific miRNAs and their targets play important to establish receptivity to implantation and their dysregulated expression may be a feature in women with early pregnancy loss. Relative expression levels of miR-340-5p, -542-3p, and -671-5p all increased following treatment of Ishikawa cells with progesterone (10 g/ml) for 24 hrs (p < 0.05). RNA sequencing of these P4-treated cells identified co-ordinate changes to 6,367 transcripts of which 1713 were predicted targets of miR-340-5p, 670 of miR-542-3p, and 618 of miR-671-5p. Quantitative proteomic analysis of Ishikawa cells transfected with mimic or inhibitor (48 hrs: n=3 biological replicates) for each of the P4-regulated miRNAs was carried out to identify targets of these miRNAs. Excluding off target effects, mir-340-5p mimic altered 1,369 proteins while inhibition changed expression of 376 proteins (p < 0.05) of which, 72 were common to both treatments. A total of 280 proteins were identified between predicted (mirDB) and confirmed (in vitro) targets. In total, 171 proteins predicted to be targets by mirDB were altered in vitro by treatment with miR-340-5p mimic or inhibitor and were also altered by treatment of endometrial epithelial cells with P4. In vitro targets of miR-542-3p identified 1,378 proteins altered by mimic while inhibition altered 975 a core of 200 proteins were changed by both. 100 protein targets were predicted and only 46 proteins were P4 regulated. miR-671-mimic altered 1,252 proteins with inhibition changing 492 proteins of which 97 were common to both, 95 were miDB predicted targets and 46 were also P4-regulated. All miRNAs were detected in endometrial biopsies taken from patients during the luteal phase of their cycle, irrespective of prior or future pregnancy outcomes Expression of mir-340-5p showed an overall increase in patients who had previously suffered a miscarriage and had a subsequent miscarriage, as compared to those who had infertility or previous miscarriage and subsequently went on to have a life birth outcome. The regulation of these miRNAs and their protein targets regulate the function of transport and secretion, and adhesion of the endometrial epithelia required for successful implantation in humans. Dysfunction of these miRNAs (and therefore the targets they regulate) may contribute to endometrial-derived recurrent pregnancy loss in women.

Structured AbstractO_ST_ABSBackgroundC_ST_ABSO_LIEndometriosis is a chronic, estrogen-dependent disease characterized by the presence of endometrial-like tissue growing outside the uterus. The molecular and clinical heterogeneity of endometriosis complicate diagnostic and treatment options -- diagnostic delays of seven to ten years are common and therapies often lack long-term efficacy. Estrogen signaling and estrogen receptor beta (ER{beta}) expression is thought to be increased in endometriosis, contributing to increased cell proliferation in lesions. The "ER{beta} dominance hypothesis" is a prevailing hypothesis in the field, setting ER{beta} as a high-priority therapeutic target. If effectively modulated, ER{beta} could be the first therapy to directly target lesion biology, rather than only managing symptoms. C_LI Objective(s)O_LIWe aimed to characterize ER{beta}s expression in endometriosis by cell type and evaluate its therapeutic relevance, primarily assessing the validity of the ER{beta} dominance hypothesis. C_LI Study DesignO_LIWe reanalyzed scRNAseq data from eight previously published studies. Our final filtered dataset included 557,061 cells, the largest endometriosis single cell atlas ever constructed. We quantified gene expression levels of ESR1 and ESR2, which encode ER[a] and ER{beta} respectively, across each tissue and cell type, to identify cell-type specific drivers of ESR2/ER{beta} expression across diseased and healthy tissues. To characterize the differences between cells that uniquely express ESR1 versus those that uniquely express ESR2, we performed differential gene expression and pathway enrichment analyses. C_LI ResultsO_LICount and distribution analyses revealed no significant ESR2/ER{beta} dominance in any cell or tissue type by Fishers Exact Tests and Wilcoxon Rank Sum Tests. Differential gene expression and pathway enrichment analyses suggest distinct roles of each estrogen receptor isoform. C_LI Conclusion(s)O_LIOverall, our results argue against a simplified model of ER{beta} dominance and instead propose a dual-isoform and cell and tissue-specific framework for understanding estrogen receptor signaling in endometriosis. These findings hold important implications for future therapeutic strategies. Specifically, treatments that target ER{beta} alone may fail to account for the functional role and relative abundance of ER. In the future, therapeutic approaches that consider isoform-specific, tissue-specific, and cell-specific expression patterns may prove most effective in reducing recurrence and improving outcomes for patients. C_LI Condensation pageO_ST_ABSTweetable statementC_ST_ABSSingle cell RNA Sequencing meta-analysis shows estrogen receptor beta is not dominantly expressed in most endometriosis tissues. Estrogen receptor alpha to estrogen receptor beta ratios vary by cell type and tissue type. Each isoform directs cell-type specific behavior in endometriosis and disease-free tissues. AJOG at a GlanceO_LIWhy was this study conducted? O_LIWe wanted to characterize estrogen receptor betas expression in endometriosis and evaluate its therapeutic relevance. C_LI C_LIO_LIWhat are the key findings? O_LIEstrogen receptor beta is not dominantly expressed in any tissue. Estrogen receptor alpha and estrogen receptor beta have disease- and cell-type specific behaviors. C_LI C_LIO_LIWhat does this study add to what is already known? O_LIIt characterizes estrogen receptor isoform expression and signaling by cell type. It also challenges the current estrogen receptor beta dominance hypothesis, meaning estrogen receptor beta may not be a key driver of endometriosis. C_LI C_LI

Ovarian stimulation (OS), utilized for the development of multiple ovarian follicles for IVF, induces supraphysiologic levels of E2 and an early rise in P4 that disrupt endometrial differentiation and decreases implantation rates or result in placental insufficiency and pregnancy complications. To improve pregnancy rates and reduce the risk of pregnancy complications associated with IVF, it is crucial to advance our molecular understanding of the molecular regulation of endometrial differentiation. Previous studies from our laboratory suggest G protein-coupled receptors (GPCRs) are important regulators of endometrial differentiation. To investigate this further, using a retrospective dataset, we identified all GPCRs expressed across the proliferative and secretory phase of the menstrual cycle and found that many members of the adhesion G protein-coupled receptor (ADGR) family are dynamically expressed. For each ADGR subfamily exhibiting differentially-expressed genes across the cycle, their expression was investigated by RT-PCR in the non-pregnant mouse uterus and decidua on E7.5 of pregnancy. For those genes expressed in the E7.5 decidua, their expression was further quantified by qPCR across early mouse pregnancy. The RT-PCR screen revealed expression of 13 ADGRs (4 of the 9 subfamilies) in E7.5 decidua and among these genes, many were differentially expressed between E0.5 and E5.5 or 6.5 and between E5.5 and E6.5. The dynamic expression of the ADGRs across the menstrual cycle and in early mouse pregnancy, suggests these ADGRs are E2- and/or P4-regulated genes. We therefore hypothesized that for these ADGR genes, mRNA expression would be disrupted in an OS cycle. This hypothesis was tested on endometrial biopsies collected in the secretory phase from prospective cohorts of women in natural and OS cycles. Consistent with the retrospective dataset, our data revealed that members of the ADGR gene family are expressed in the secretory phase of the natural menstrual cycle and for the first time, we show that their expression is altered by ovarian stimulation.

Study questionWhich proteins underpin oocyte developmental competence, as modelled by oocytes of variable competence matured in vivo, or matured in vitro under different conditions (capacitation in vitro maturation (CAPA) or standard in vitro maturation (IVM))? Summary answerSignificant differences in the global proteome were observed in both oocytes and their corresponding cumulus cells depending on the mode of oocyte maturation, with key variations in eukaryotic translation, autophagy and endocytosis pathways within oocytes, and changes in reactive oxygen species detoxification and serine biosynthesis in cumulus cells. What is known alreadyWithin the ovarian follicle, mammalian oocytes must acquire the necessary molecular machinery to support successful fertilisation and embryonic development. Close contact with the surrounding cumulus cells ensures coordinated nuclear and cytoplasmic maturation of the oocyte, along with the accumulation of proteins stored within the oocyte in cytoplasmic lattices and endo-lysosomal vesicular assemblies. Study design, size, durationThis basic science study utilised a mouse model to assess proteomic changes across three oocyte competence models. Key proteins identified in mouse oocytes were also assessed in discarded immature human germinal vesicle (GV) oocytes and MII oocytes following rescue-IVM. Three oocyte maturation methods were tested: i) in vivo maturation, (ii) CAPA and (iii) standard IVM. In vivo maturation served as a positive control group, whereby metaphase II (MII) mature oocytes were collected from mice stimulated with pregnant mare serum gonadotropin (PMSG) and triggered with human chorionic gonadotropin (hCG), simulating full ovarian stimulation. For the in vitro maturation groups, immature cumulus oocyte complexes (COCs) were collected from mildly stimulated (23 hr PMSG) mice. For the standard IVM group, immature COCs were matured in media containing amphiregulin and epiregulin for 18 hours. For the CAPA group, COCs were held for 24 hours in pre-IVM conditions in the presence of c-type natriuretic peptide (CNP), oestradiol, insulin and follicle stimulating hormone (FSH), and then matured via IVM in media containing FSH, amphiregulin and epiregulin. Four biological replicates were performed for mouse proteomics experiments, three biological replicates performed for mouse immunocytochemistry experiments and six replicates were performed for embryology experiments. Participants/materials, settings, methodsFour to six-week-old C57BL/6JAusb mice were used for all mouse experiments. Embryology outcomes were used to confirm the variation in oocyte developmental competence between the three maturation groups. For the in vivo, CAPA and IVM groups, mature MII COCs were collected and separated into oocytes and cumulus cells. Oocytes and cumulus cells were subjected to mass spectrometry and bioinformatic analysis was performed using Proteome Discoverer and Ingenuity Pathway Analysis, with data validated by immunofluorescence. To assess conservation of proteins in human oocytes, 49 oocytes were collected from 36 patients following assisted reproduction technology (ART) cycles and subject to immunofluorescence. Rescue-IVM was also performed with half of the human oocyte cohort to obtain MII oocytes. Main results and the role of chanceProteomic profiling identified around 1600 proteins in mouse oocytes and 3100 in mouse cumulus cells across all three treatment groups (at least 2 peptides per protein). Differential expression analysis and pattern analysis collectively revealed a signature of proteins that were consistently differentially expressed between in vivo and in vitro oocyte maturation systems (log2FC of {+/-} 1 and a p-value [&le;] 0.05). These subsets of proteins were mapped to biological processes including eukaryotic translation, autophagy and endocytosis pathways within oocytes. Orthogonal validation of clathrin, ribosomal protein L24 and eukaryotic initiation factor 2A supported the proteomic findings and expression was conserved in human oocytes. Changes in reactive oxygen species detoxification and serine biosynthesis were observed in mouse cumulus cells, with fluorescence intensity changes in ferredoxin-1 and phosphoglycerate dehydrogenase supporting the dysregulation of cumulus cell processes during in vitro maturation. Large scale dataThe mass spectrometry data are available via ProteomeXchange with identifier PXD073269. Limitations, reasons for cautionThe foundational mechanisms of oocyte developmental competence remain elusive, particularly in humans where MII oocytes are heterogenous in quality within the same stimulation cycle and patient. In this study, C57Bl6/J mice were used as the model species, allowing precise control over differing models of oocyte quality and capacity to analyse large numbers of oocytes. However, care is required when interpreting the significance of these findings in mice to mechanisms regulating human oocyte quality. Nonetheless, the in vivo stimulation and both IVM protocols used in this study are clinically relevant and developmentally matched. This study has also not addressed oocyte developmental competence in gonadotropin-free IVM oocytes, which is now a clinical reality. Wider implications of the findingsThis study confirms that mouse oocytes, matured in vitro in two clinically relevant systems, show reduced developmental competence when compared to in vivo matured oocytes. Through examination of the global proteome in oocytes, molecular pathways including eukaryotic translation, autophagy and endocytosis were dysregulated in in vitro oocytes. Recent findings have revealed the critical role of these pathways to developmental competence in the context of in vivo development. In cumulus cells, changes in reactive oxygen species detoxification and serine biosynthesis were observed, adding to the extensive knowledge around metabolic activity in cumulus cells as a critical facet of oocyte quality. Combined, this data suggests that the necessary processes of protein storage and degradation in oocytes and metabolism in cumulus cells constitute important components of oocyte quality. These processes appear suboptimal in current IVM systems, providing a future research direction to optimise IVM protocols with consideration to these protein pathways. Study funding/competing interestsThis study was funded by a National Health and Medical Research Council Investigator Fellowship (APP1023210) awarded to R.B.G. and by a gift from Open Philanthropy. The following competing interests are declared: R.B.G.is a consultant to Dioseve Inc.. L.E.W is a co-founder, shareholder, director and advisor of Jumpstart Fertility Inc.. L.E.W. is also an advisor and shareholder in EdenRoc Sciences, the parent company of Metro Biotech NSW and Metro Biotech, and in Life Biosciences LLC and its daughter companies. His UNSW Industry Scientia position is partly funded by Proto Axiom. All other authors have no competing interests to disclose.

STUDY QUESTIONCan network modelling of single cell transcriptomic data identify cellular developmental trajectories of fallopian tube (FT) epithelium and reveal functional and pathological divergence from the endometrium? SUMMARY ANSWERA bidirectional secretory and ciliated differentiation trajectory was apparent from a novel OVGP1+ progenitor population of FT epithelial cells. A causal network model of whole transcriptome action in the FT and endometrium revealed specific functional divergence between secretory cells of these tissues. The network model reflected the latest ectopic pregnancy genome wide association study (GWAS), invoking MUC1 and other candidate genes in mature secretory cells for ectopic and eutopic implantation. WHAT IS KNOWN ALREADYThe fallopian tube forms the in vivo peri-conceptual environment, which has a significant impact on programming offspring health. The fallopian tube epithelium establishes this environment, however the epithelial cell types are poorly characterised in health and disease. STUDY DESIGN, SIZE, DURATIONPublicly available benign FT single cell RNA sequencing (scRNA-seq) samples from thirteen women across three studies were combined. Endometrial scRNA-seq samples from thirteen women from one study were used to demonstrate transcriptomic differences between the epithelia of the two tissues. Network models of transcriptomic action were constructed with hypergraphs. PARTICIPANTS/MATERIALS, SETTING, METHODSA meta-analysis of FT scRNA-seq samples was performed to identify epithelial populations. Differential gene expression assessed differences between fallopian tube and endometrial epithelial scRNA-seq data. Functional differences between secretory cells in the tissues were characterised using hypergraph models. To identify associations with ectopic pregnancy, expression quantitative trait loci (eQTLs) from a recent GWAS were mapped onto the network models. MAIN RESULTS AND THE ROLE OF CHANCEEpithelial cells (n=14,360) were clustered into 8 secretory and ciliated epithelial populations in the meta-analysis of 3 scRNA-seq datasets. A novel OVGP1+ epithelial progenitor cell was also identified, and its bi-directional differentiation to mature secretory or mature ciliated populations was mapped by RNA velocity analysis. This progenitor exhibited a high velocity magnitude (12.47) and low confidence (0.69), a combination strongly indicative of multipotent progenitor status. Comparing FT epithelial cells with endometrial epithelial cells revealed 5.3-fold fewer shared genes between FT and endometrial glandular secretory cells than between FT and endometrial ciliated cells, suggesting functional divergence of secretory cells along the reproductive tract. Hypergraphs were used to identify highly coordinated regions of the transcriptome robustly associated with functional gene networks. In the FT secretory cells, these networks were enriched for lipid (FDR<0.002) and immune (FDR<0.00007) related pathways. We mapped eQTLs from a GWAS meta-analysis of 7070 women with ectopic pregnancy over a range of significance (P = 1.68 x 10-21- 5.8 x 10-4) to the hypergraphs of FT and endometrium. Of the 22 genes present in the hypergraphs, 13 of these clustered as highly coordinated genes. This demonstrated the functional importance of MUC1 in the FT and endometrium, (GWAS Study P = 5.32x10-9) and identified additional genes (SLC7A2, CLDN1, GLS, PEX6, PLXNA4, NR2F1, CLGN, PGGHG, ANKRD36) implicated in ectopic pregnancy and eutopic pregnancy. LIMITATIONS, REASONS FOR CAUTIONThe sample size of reproductive age women was limited in previous studies, and though causal network modelling was used and previous mechanistic data supports candidate gene involvement, no in vitro or in vivo validation of candidate was performed. WIDER IMPLICATIONS OF THE FINDINGSThese findings consolidate the existing single cell transcriptomic datasets of the FT to provide a comprehensive understanding of epithelial populations and define functionally distinct secretory cells that contribute to the peri-conceptual environment of the FT. We further implicate the role of MUC1 and secretory cells in ectopic pregnancy and suggest future targets for investigating embryo implantation in the FT and endometrium.

Understanding the molecular pathways that underpin ovarian development and function is vital for improving the research approaches to investigating fertility. Despite a significant improvement in our knowledge of molecular activity in the ovary, many questions remain unanswered in the quest to understand factors influencing fertility and ovarian pathologies such as cancer. Here we present an investigation into the expression and function of developmental transcription factor LIM Homeobox 9 (LHX9) in the adult mouse ovary. We have characterised Lhx9 expression in several cell types of the mature ovary across follicle stages. To elucidate the function of this expression, we carried out an investigation of ovarian anatomy and transcription in a Lhx9+/- knockout mouse model displaying subfertility. Despite a lack of gross anatomical differences between genotypes, RNA-sequencing found that 90 genes were differentially expressed between Lhx9+/- and Lhx9+/+ mice. Gene ontology analyses revealed a downregulation of genes with major roles in ovarian steroidogenesis and an upregulation of genes with implications for ovarian cancer. Analysis of the ovarian epithelium revealed Lhx9+/- mice have a disorganised epithelial phenotype and a significant increase in epithelial marker gene expression. These results provide an analysis of Lhx9 in the adult mouse ovary and a new candidate for fertility research and ovarian epithelial cancer. Summary sentenceLhx9 haploinsufficient mice are subfertile with altered expression of steroid genes in the adult ovary and abnormal ovarian surface epithelium.

BackgroundMitochondrial dysfunction is a leading contributor to the decline in oocyte quality associated with maternal aging. Prior investigations of mitochondrial function in the ovarian follicle have largely treated the mitochondrial pool as a homogeneous population, reporting aggregate values that may obscure biologically meaningful differences between distinct mitochondrial subpopulations. The present study addresses this limitation by characterizing mitochondrial subpopulation dynamics in oocytes and cumulus granulosa cells at single-organelle resolution using fluorescence-activated mitochondria sorting (FAMS). ResultsAnalysis of the aggregate mitochondrial population in mouse oocytes revealed no significant age-associated differences in mitochondrial DNA copy number or membrane potential, a result that would previously have been interpreted as evidence of minimal age-related mitochondrial change. Subpopulation analysis revealed this conclusion to be incomplete: aged oocytes showed significantly elevated mitochondrial DNA copy number specifically within the high membrane potential and small mitochondrial subpopulations, with no significant differences in the low membrane potential or large subpopulations. NMN supplementation normalized mitochondrial DNA copy number in the high membrane potential and small subpopulations toward young levels while producing an opposing effect in large mitochondria, demonstrating subpopulation-specific rather than uniform rejuvenation. In cumulus cells, significant age-associated changes were detectable at the aggregate level, including a reduction in mitochondrial DNA copy number and an elevation in membrane potential, and subpopulation analysis further resolved these findings. The age-associated reduction in cumulus cell mitochondrial DNA copy number was driven predominantly by the high membrane potential subpopulation. NMN supplementation exerted opposing effects on small and large cumulus cell mitochondrial subpopulations, increasing mitochondrial DNA copy number above both young and aged levels in small mitochondria while further reducing it below aged levels in large mitochondria. ConclusionsViewing the mitochondrial pool as a heterogeneous mixture of functionally distinct subpopulations rather than a uniform population reveals age-associated alterations in oocytes and cumulus cells that are undetectable by aggregate analysis. NMN supplementation exerts subpopulation-specific effects in both cell types, identifying specific mitochondrial subtypes as more precise targets for future mechanistic investigation of age-associated infertility than the mitochondrial pool considered in aggregate.

Uterine luminal fluid (ULF) composition plays a major role in cell-to-cell communication between the receptive endometrium and an invading blastocyst. ULF is made up of secretions from the uterine glands and uterine epithelial cells (UEC). However, the cellular mechanisms regulating these exocytotic secretions are not yet understood. This study investigated the role of extracellular vesicles (EVs) during early pregnancy using Transmission Electron Microscopy (TEM). TEM analysis at time of fertilisation (TOF) Day 1 and at time of receptivity (TOR) Day 5.5 revealed EVs present, with an abundance at TOR. Exocytosis signalling in UECs, by SNARE proteins syntaxin 2 (syn2) and SNAP23, was also examined. Immunofluorescence microscopy showed both syn2 and SNAP23 to be present in the apical area of UECs at TOR. Western blot and immunofluorescence quantification revealed a significant increase in syn2 and SNAP23 at TOR compared to TOF. SNAP23 colocalization with apical actin showed SNAP23 was in the luminal space contributing to ULF. Overall, this data shows EVs, syn2 and SNAP23 (potential receptivity marker) are present in ULF and may together create a favourable microenvironment for blastocyst implantation. Summary statementDuring uterine receptivity SNAREs participate in the secretion of ULF. EVs and SNAP23 are present in the uterine luminal space during uterine receptivity. SNAP23 has the potential to be used as a receptivity marker.

During gonadotropin-induced ovarian follicle development, an antral cavity forms within the layers of granulosa cells (GCs). Gonadotropin stimulation also differentiates the GCs into two distinct lineages: mural GCs (mGCs), which surround the antral cavity, and cumulus GCs (cGCs), which stay in contact with the oocyte. We examined the transcriptomes of mouse mural and cumulus cells to understand the mechanism of differentiation. In addition to analyzing a single transcript expression per gene, we also considered multiple isoform expressions to explore differential transcriptomics. GC-specific core transcription factors Foxl2, Nr5a1, Nr5a2, Runx1, and Runx2 were expressed at high levels in mGCs but downregulated in cGCs, indicating that cGCs acquire a more differentiated state. Both single-transcript and multiple-isoform analyses revealed differential expression of about 70% of transcripts between mGCs and cGCs. Although the counts were similar, the differentially expressed genes (DEGs) at the single transcript level did not correlate well with the respective differentially expressed transcript isoforms (DETI). We identified DETIs originating from key epigenetic and transcriptional regulator genes, such as Chd1, Ezh2, Kdm5a, Kdm5b, Gata4, Esr2, Fos, Myc, and Ybx1, that were not differentially expressed at the single-transcript analysis. Further analysis revealed a transcript switch in one-third of the DETIs. Most of the transcript isoforms were protein-coding, followed by non-coding regulatory RNAs. A total of 1,302 transcript isoforms were silenced in cGCs, including those of Adar, Cebpa, Dnmt3a, Foxo4, Pgr, Rest, Runx1, Satb2, Sirt1, Sirt2, and Tead1. Conversely, 529 transcript isoforms were activated in cGCs, including transcripts for Brd7, Crem, Chd1, Med21, Med27, Nfkbia, Rbm39, Rbmx, Suv39h2, Tcf12, Xist, and Ybx3. Additionally, 57 genes exhibited DETIs, with at least one isoform turned off and another turned on in cGCs, including Csde1, Dab2, Ezh2, Gata4, Gnas, Gtf2i, Macf1, Klf10, Setdb1, and Sp3. Finally, we explored the mechanisms underlying transcript switching during the differentiation of mGCs and cGCs. Our findings suggest that gonadotropin-induced transcript switching in GCs is crucial for mural and cumulus granulosa differentiation, a key insight that would be missed without mRNA isoform analysis.

Study questionCould follicular fluid-derived extracellular vesicles (ffEVs) benefit human oocyte rescue in vitro maturation (rIVM)? Summary answerSupplementation of rIVM culture with ffEVs isolated from mature follicles enhanced oocyte maturation rates by >20%, inducing changes in oocyte protein profile and organelle distribution. What is already knownIVM involves the culture of immature germinal vesicle (GV) oocytes under set laboratory conditions to allow for their transition to mature metaphase II (MII) stage, which is confirmed by the extrusion of the first polar body. Efficient IVM could circumvent aggressive controlled ovarian stimulation (COS), reduce the cost and broaden the repertoire of infertility treatments. Animal studies suggest that extracellular vesicles (EVs), membranous nanosized vesicles containing different molecular content (e.g. nucleic acids, proteins) and present in the ovarian follicular fluid could enhance oocyte maturation. The uptake of ffEVs by bovine, equine and feline oocytes, but not human, has been demonstrated. Study design, size, durationWomen undergoing transvaginal oocyte retrieval after COS (n=83) were recruited to donate follicular fluid (n=54 single follicles) and/or immature GV oocytes (n=95). We aimed to: a) define differences in the protein cargo of ffEVs derived from human follicles containing mature (MII-ffEVs, n=10) versus immature (GV-ffEVs, n=5; metaphase I MI-ffEVs, n=5) oocytes, b) demonstrate the capacity of human GV oocytes to uptake MII-ffEVs and c) determine the effect of MII-ffEVs supplementation on oocyte maturation. Participants/materials, setting, methodsffEVs were isolated by ultracentrifugation. The protein content of ffEVs was analysed by mass spectrometry. The uptake of fluorescently-labelled MII-ffEVs by GV oocytes (n=15) was assessed by confocal microscopy. GVs were cultured for rIVM in a timelapse incubator with MII-ffEVs (n=45 GVs) or without (n=40 GVs) and extrusion of polar body denoted maturation. The impact of MII-ffEVs supplementation on IVM-matured oocytes was assessed through single-cell proteomics and intracellular organelles appearance on transmission electron microscopy (TEM). Main results and the role of chanceWe identified 1340 proteins in ffEVs, with proteins such as F12, IGKV1-39, FREM2, and C1QC being significantly enriched in MII-ffEVs. GV oocytes internalised MII-ffEVs, and their supplementation for 48 hours increased the oocyte maturation rate compared to control by 22.8{+/-}9.4% (77.8% vs 55% maturation rate respectively; p-value=0.0372). Proteomic analysis of ffEV-supplemented mature oocytes (n=6) revealed 56 differentially abundant proteins (DAPs) compared to not supplemented mature oocytes (n=5). Among them, 37 DAPs were in higher abundance in ffEVs- supplemented mature oocytes including Hyaluronan Synthase 1 (HAS1) that is associated with oocyte maturation (6.55 fold increase). Electron microscopy showed differences in oocyte organelle distribution and appearance, particularly that of endoplasmic reticulum (RE) and RE-mitochondria complexes. Functional enrichment analysis of differentially abundant proteins during ffEV-oocyte interaction revealed regulation of endoplasmic reticulum, steroid biosynthesis, and keratin organisation pathways. Large scale dataN/A Limitations, reasons for cautionThis study utilised immature oocytes from COS cycles, therefore the results should be interpreted within the context of rIVM potential. Winder implications of the findingsThese results provide new insights into the role of ffEVs in enhancing oocyte maturation, offering potential improvements for clinical rIVM protocols and inspire the development of global IVM supplements based on ffEVs or associated specific cargo. Study funding/competing interest(s)This work was funded by an EMDO research fellowship and a FAN research grant (Fonds zur Forderung des akademischen Nachwuchses) from the University of Zurich. What does it mean for the patientsInfertility rates are rising, with 17% of couples worldwide needing help to get pregnant, often through treatments like in vitro fertilisation (IVF). IVF usually involves using hormones to stimulate the ovaries to produce multiple eggs, which can be tough on a womans health, both physically and emotionally, and can be very expensive. In vitro oocyte maturation (IVM) is a gentler alternative, where eggs are matured outside the body, reducing risks and costs. However, IVM isnt as effective as IVF yet, mainly because the current methods are not perfect. Our research is exploring a new approach to improve IVM by adding extracellular vesicles from follicular fluid to the egg culture. This could help the eggs mature better, leading to higher success rates and giving more options to couples struggling with infertility.

We created the c.1286C>G stop-gain mutation found in a family with primary ovarian insufficiency (POI) at age 30 years. The Eif4enif1 C57/Bl6 transgenic mouse model contained a floxed exon 10-19 cassette with a conditional knock-in cassette containing the c.1286C>G stop-gain mutation in exon 10. The hybrid offspring of CMV-Cre mice with Eif4enif1WT/flx mice were designated Eif4enif1WT/{Delta} for simplicity. A subset of female heterozygotes (Eif4enif1WT/{Delta}) had no litters. In those with litters, the final litter was earlier (5.4{+/-}2.6 vs. 10.5{+/-}0.7 months; p=0.02). Heterozygous breeding pair (Eif4enif1WT/{Delta} x Eif4enif1WT/{Delta}) litter size was 60% of WT litter size (3.9{+/-}2.0 vs. 6.5{+/-}3.0 pups/litter; p<0.001). The genotypes were 35% Eif4enif1WT/flx and 65% Eif4enif1WT/{Delta}, with no homozygotes. Homozygote embryos did not develop beyond the 4-8 cell stage. The number of follicles in ovaries from Eif4enif1WT/{Delta} mice was lower starting at the primordial (499{+/-}290 vs. 1445{+/-}381) and primary follicle stage (1069{+/-}346 vs. 1450{+/-}193) on day 10 (p<0.05). The preantral follicle number was lower starting on day 21 (213{+/-}86 vs. 522{+/-}227; p<0.01). Examination of ribosome protected mRNAs (RPR) demonstrated altered mRNA expression. The Eif4enif1 stop-gain mice replicate the POI phenotype in women. The unique mouse model provides a platform to study regulation of protein translation across oocyte and embryo development in mammals.

Equine endometrosis is a major cause of subfertility in mares characterized by fibrotic remodeling of the endometrium. Although transforming growth factor beta 1 (TGF-{beta}1) is implicated in fibrogenesis, the relationship between endometrosis severity and transcripts associated with tissue maintenance and proliferation remains incompletely defined. Present study evaluated endometrial mRNA expression of IGF1, MKI67, TGFB1, and ACTA2 in relation to endometrosis severity and defined histopathological features. Forty-seven endometrial samples were graded according to the modified Kenney and Doig (KD) categories. Relative mRNA expression was quantified by RT-qPCR and histopathology was extended using a standardized feature-based assessment. TGFB1 mRNA expression was higher in category I+ than in categories I and III (p = 0.041) and in samples with glandular basal lamina disruption (p = 0.020). MKI67 mRNA expression was lower in samples with luminal epithelial erosion (p = 0.049). IGF1 mRNA expression correlated negatively with KD category ({rho} = -0.401, p = 0.015), glandular degeneration ({rho} = -0.340, p = 0.043), overall inflammatory infiltration ({rho} = -0.387, p = 0.020), lymphocytic infiltration ({rho} = -0.426, p = 0.010), and neutrophilic infiltration ({rho} = -0.448, p = 0.006). MKI67 correlated positively with ESR1 ({rho} = 0.887, p < 0.001). These findings indicate that early endometrosis-compatible lesions are associated with increased TGFB1 transcription and that epithelial damage is accompanied by reduced MKI67 expression. The inverse associations between IGF1 expression and both lesion severity and inflammatory infiltration support a link between progressive histopathological changes and reduced expression of a growth factor involved in tissue maintenance.

Recurrent implantation failure (RIF) is defined after three or more good quality embryo transfers following in vitro fertilisation without a successful pregnancy outcome. Many factors contribute to RIF however, the endometrial contribution remains unclear. Previous work by our group has identified a micro-RNA (miRNA) miR-185-5p as conserved across placental mammal irrespective of implantation strategies. We tested the hypothesis that miR-185-5p and the pathways it regulates, may be disrupted in the endometria of women with RIF. A human endometrial epithelial cells line (Ishikawa cells) was transfected with mimics or inhibitors for miR-185-5p for 24 (for implantation assay) or 48 hr (for proteomic analysis) along with non-targeting controls. There was a significant different in percentage attachment of BeWoW spheroids to cells transfected with miR-185-5p mimic compared to inhibitor (P<0.05). Transfection of epithelial cells with miR-185-5p altered expression of 1450 (mimic alone) and 509 (inhibitor alone) proteins respective of which, 146 were modified by both. Comparison of predicted targets of miR-185-5p, proteins modified by this study, and key endometrial genes from the literature determined genes and proteins associated with CNP family were further investigated in biopsies from individuals with (n=10) and without RIF (n=9) with CSNK1D expression significantly lower (p<0.05) in individuals with RIF. Collectively these data demonstrate that miR-185-5p modifies pathways that are important for successful implantation in humans.

Study questionWhat are the temperature, pH and uterine fluid composition in the human uterus three days following a positive LH test or ovum pick-up? Summary answerThe mean uterine temperature was 36.94{+/-}0.26{degrees}C, the mean uterine pH was 6.76{+/-}0.22, and the concentrations of 37 components in aspirated uterine fluid were successfully determined. What is known alreadyEmbryo culture conditions in the laboratory impact key outcomes of IVF/ICSI treatments, such as the quality of the embryos and the live birth rate after treatment, and child outcomes, such as birth weight. Currently used conditions, including temperature, pH, and culture medium composition, are largely derived from clinical experience and experimental studies using animal models. Limited studies have been performed to determine the natural human preimplantation embryo environment in vivo during the physiologically relevant time of the menstrual cycle. This type of fundamental knowledge is required for evidence-based optimization of the in vitro embryo culture environment and improving IVF/ICSI outcomes. Study design, size, durationIn this cross-sectional study, conducted between April 2015 and March 2016, temperature and pH were measured in the human uterine cavity on the third day following a positive LH test or ovum pick-up, and uterine fluid was simultaneously aspirated for composition analysis. Uterine temperature was measured in fifty eight women, uterine pH was determined in fifty three women, and twenty two samples of aspirated uterine fluid were analysed for the concentrations of thirty-seven components. Participants/materials, setting, methodsThis study involved 61 healthy reproductive-aged women: 53 without ovarian stimulation and 8 who underwent ovarian stimulation. We measured uterine temperature using a probe inserted into the uterine cavity directly, and uterine pH after inserting a probe through the outer sheath of an IVF catheter. Uterine fluid was then aspirated using this outer IVF catheter and a 10 ml syringe, and subsequently analysed with a Cobas 8000 chemistry analyser and ultra-performance liquid chromatography-tandem mass spectrometry. Main results and the role of chanceThe mean uterine temperature on the third day following a positive LH test or ovum pick-up was 36.94 {+/-} 0.26{degrees}C and correlated with the womens core body temperature. The mean pH in the uterine cavity was pH 6.76 {+/-} 0.22, clearly lower than the standard pH used for human preimplantation embryo culture in vitro (pH 7.3 {+/-} 0.1). Concentrations of important energy sources were 0.8 {+/-} 0.02 mM pyruvate, 5.1 {+/-} 1.78 mM glucose and 6.60 {+/-} 1.12 mM lactate. Glutamic acid (1162 {+/-} 183 M), glycine (955 {+/-} 156 M) and alanine (513 {+/-} 82 M) were the most abundant amino acids in uterine fluid. Limitations, reasons for cautionIn absence of a preimplantation embryo, synergistic influences on the uterine environment may be overlooked. Single centre and specific population limitations may hinder broader generalization of the results. Uterine fluid likely contains additional components. Wider implications of the findingsThe in vivo uterine characteristics identified in this study are foundational to develop an in vivo evidence-based culture medium for human embryos. Further research is necessary to evaluate whether such a medium can improve human preimplantation embryo development and quality, thereby increasing cumulative live birth rates and improving child outcomes.

Early embryo loss affects all mammalian species, including humans and agriculturally important food-producing mammals such as cattle. The developing conceptus (embryo and extra-embryonic membranes) secretes factors which modify the endometrium and can be critical for early pregnancy processes such maternal recognition of pregnancy (MRP) and enhancing uterine receptivity to implantation. For example, a competent bovine conceptus secretes IFNT to initiate MRP. The bovine conceptus also secretes other proteins at the time of MRP, including CAPG and PDI, which are highly conserved among placental mammals. We have previously shown that these proteins act upon the endometrium to modulate receptivity, embryo development, and implantation in species with different implantation strategies (humans and cattle). We hypothesise that developing a novel 3D bovine endometrium on a chip system will enhance our understanding of the role of conceptus-derived factors in altering the endometrium and/or ULF secretion. Here we have developed a 3D bovine endometrium on a chip system, comprising both stromal and epithelial cell culture combined with culture medium flow better mimics the in vivo endometrium and exposure to conceptus-derived factors than conventional 2D endometrial cell culture. We have demonstrated that the conceptus-derived proteins CAPG and PDI modulate the endometrial transcriptome and secretory response to promote pathways associated with early pregnancy and alter ULF composition. This work highlights the critical need for more robust and in vivo -like culture systems to study endometrial-conceptus interactions in vitro to further investigate the role of conceptus derived factors for pregnancy success. SIGNIFICANCE STATEMENTWe have developed an in vitro 3D bovine endometrium-on-a-chip system comprising both primary stromal cells under static conditions and epithelial cells under flow conditions to mimic the in vivo endometrial environment from the conceptuses perspective. The secretome of the 3D endometrium-on-a-chip was characterised, was found to contain proteins associated with cell adhesion and tissue development, and contained proteins previously identified in in vivo uterine luminal fluid. PDI and CAPG (previously identified conceptus-derived factors) altered the transcriptome and secretome of cells within the system. Exposure to CAPG or PDI altered the secretome of proteins previously identified in pregnant uterine luminal fluid or associated with early pregnancy, and exposure to CAPG or PDI also altered the transcriptome to support processes such as immune response, secretion, proliferation, and adhesion related pathways. This data supports previously published works and highlights the need for the use of more in vivo-like in vitro models to study conceptus-endometrial interactions.

Open testicular biopsy is a commonly indicated procedure for diagnosis of testicular histopathology prior to referral to testicular sperm extraction (TESE) or microsurgical testicular sperm extraction (M-TESE) in men with non-obstructive azoospermia (NOA). There are known hematological changes resulting from the rupture of the blood-testis barrier in the TESE and M-TESE procedures, but changes to the microvasculature have not yet been described when the open biopsy is performed prior to spermatozoid collection for intracytoplasmic sperm injection. In this experimental study, open biopsy was performed on testes from adult rabbits. After a 45 days recovery period, the animals underwent a laparotomy for the surgical removal of the aortic patch, both gonadal arteries, the vasa deferentia, and both testicles. The laparotomy was followed by an angiography. The comparative results demonstrate a breakdown in the vascularization of the testicles biopsied relative to the microvasculature pattern of the tunicae albugineae of the intact testicles. The vascular damage resulting from open testicular biopsy reflects one more negative impact on spermatogenic function of previously lesioned testicles besides the known alterations (fibrosis, decrease in testosterone levels, hematological changes). Therefore, we suggest that the M-TESE should be the choice method for sperm retrieval in men with NOA and it should be planned and performed with simultaneous diagnostic and therapeutic objectives in order to increase the patients chances of reproductive success.

Structured AbstractO_ST_ABSPurposeC_ST_ABSTo determine if rescue in vitro maturation (IVM) of human oocytes can be improved by co-culture with ovarian support cells (OSCs) derived from human induced pluripotent stem cells (hiPSCs). MethodsFertility patients undergoing conventional ovarian stimulation for oocyte cryopreservation or IVF donated denuded immature germinal vesicle (GV) and metaphase I (MI) oocytes for research, which were allocated between either the control or intervention cultures. Fertility patients aged 25 to 45 years old donated immature oocytes under informed consent, with no additional inclusion criteria. The 24-28 hour OSC-IVM culture condition was composed of 100,000 OSCs in suspension culture with human chorionic gonadotropin (hCG), recombinant follicle stimulating hormone (rFSH), androstenedione and doxycycline supplementation. The Media-IVM control lacked OSCs and contained the same supplementation. Primary endpoints consisted of MII formation rate and morphological quality assessment. Additionally, metaphase spindle assembly location and oocyte transcriptomic profiles were assessed compared to in vivo matured MII oocyte controls. ResultsWe observed significant improvement in maturation outcome rates ([~]1.7X) for oocytes that underwent IVM with OSCs. Specifically, the OSC-IVM group yielded a maturation rate of 62% {+/-} 5.57% SEM versus 37% {+/-} 8.96% SEM in the Media-IVM (p=0.0138, unpaired t-test). Oocyte morphological quality between OSC-IVM and the Media-IVM control did not significantly differ. OSC-IVM resulted in MII oocytes with no instances of spindle absence and no significant difference in position compared to in vivo matured IVF-MII controls. OSC-IVM treated MII oocytes display a transcriptomic signature significantly more similar to IVF-MII controls than the Media-IVM control MII oocytes did. ConclusionThe novel OSC-IVM platform is an effective tool for rescue maturation of human oocytes obtained from conventional stimulation cycles, yielding oocytes with improved nuclear and cytoplasmic maturation. OSC-IVM shows broad utility for application in modern fertility treatment to improve the total number of available mature oocytes for fertility treatment.

Human placental tissues have variable rates of SARS-CoV-2 invasion resulting in consistently low rates of fetal transmission suggesting a unique physiologic blockade against SARS-CoV-2. Angiotensin-converting enzyme (ACE)-2, the main receptor for SARS-CoV-2, is expressed as cell surface and soluble forms regulated by a metalloprotease cleavage enzyme, ADAM17. ACE-2 is expressed in the human placenta, but the regulation of placental ACE-2 expression in relation to timing of maternal SARS-CoV-2 infection in pregnancy is not well understood. In this study, we evaluated ACE-2 expression, ADAM17 activity and serum ACE-2 abundance in a cohort of matched villous placental and maternal serum samples from Control pregnancies (SARS-CoV-2 negative, n=8) and pregnancies affected by symptomatic maternal SARS-CoV-2 infections in the 2nd trimester ("2ndTri COVID", n=8) and 3rd trimester ("3rdTri COVID", n=8). In 3rdTri COVID as compared to control and 2ndTri-COVID villous placental tissues ACE-2 mRNA expression was remarkably elevated, however, ACE-2 protein expression was significantly decreased with a parallel increase in ADAM17 activity. Soluble ACE-2 was also significantly increased in the maternal serum from 3rdTri COVID infections as compared to control and 2ndTri-COVID pregnancies. These data suggest that in acute maternal SARS-CoV-2 infections, decreased placental ACE-2 protein may be the result of ACE-2 shedding. Overall, this work highlights the importance of ACE-2 for ongoing studies on SARS-CoV-2 responses at the maternal-fetal interface.