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Infertility affects between 8 and 12% of reproductive-age couples worldwide. Despite improvements in assisted reproductive techniques (ART), live birth rates are still limited. In clinical practice, imaging and microscopy are currently widely used, but their diagnostic effectiveness remains limited. In research, the emergence of innovative techniques named OMICS would improve the identification of the implantation window, while progressing in the understanding of the pathophysiological mechanisms involved in embryo implantation failures. To date, transcriptomic analysis seems to be the most promising approach in clinical research. The objective of this review is to present the results obtained with the different approaches available in clinical practice and in research to assess endometrial receptivity in patients undergoing ART., L’infertilité touche entre 8 et 12 % des couples en âge de procréer à travers le monde. Malgré l’amélioration des techniques d’aide médicale à la procréation (AMP), les taux de naissances vivantes restent toujours limités. En pratique clinique, l’imagerie et la microscopie sont actuellement largement utilisées, mais leur efficacité diagnostique reste limitée. En recherche, l’émergence des techniques innovantes dites OMICS permettrait d’améliorer l’identification de la fenêtre implantatoire, tout en progressant dans la compréhension des mécanismes physiopathologiques impliqués dans les échecs d’implantation embryonnaire. À ce jour, l’approche transcriptomique semble être la piste la plus prometteuse en recherche clinique. L’objectif de cette revue est de faire un état des lieux des résultats obtenus à ce jour avec les différentes approches disponibles en pratique clinique et en recherche pour évaluer la réceptivité endométriale chez les patientes prises en charge en AMP.

Study question Are the oocytes, embryos, granulosa and cumulus cells, used during ART, susceptible to the SARS-CoV–2 infection? Summary answer Transcriptomic analyses of SARS-CoV–2-associated receptors and proteases strongly suggest that blastocysts are most permissive to SARS-CoV–2 compared with mature oocytes and day 3 embryos. What is known already Very few studies analyzed the gene expression profiles of SARS-CoV–2-associated receptors and proteases, mainly focusing on ACE2 and TMPRSS2 expression, resulting in partial knowledge in different specimens from female genital tract. To date, the gene expression profile of SARS-CoV–2 host entry candidates in the entire preimplantation embryos is scarcely available. Moreover, reports on oocyte and granulosa cells susceptibilityto SARS-CoV–2 are very sparse. Study design, size, duration To address this question, we retrospectively examined the gene expression profiles of SARS-CoV–2-associated receptors and proteases in human granulosa cells (GCs), cumulus cells (CCs), mature oocytes, day 3 embryos, blastocysts and trophectoderm cells obtained from our previously described Affymetrix microarray data. Participants/materials, setting, methods Human GCs and CCs (n = 17), mature oocytes (n = 6), and preimplantation embryos (n = 20) were analyzed. The comparison of gene expression levels of receptors and proteases closely related to SARS-CoV–2 infection. For each gene, the number of samples with the probe set ‘present’, based on the detection call, was analyzed. Each probe set was classified according to the signal intensity value median, as low (200). Main results and the role of chance ACE2, BSG, CTSL, CTSA were detectable at high expression level in all mature oocyte samples, while only CTSL was strongly expressed in all day 3 embryos. The most representative dual co-expression of SARS-CoV–2-associated receptor and protease (60% of samples) during the embryonic genome activation stage (EGA) was ACE2-CTSL and BSG-CTSL. In blastocysts, ACE2, BSG, CTSL, CTSA and FURIN were detectable in the entire cohort at high expression level, and the prevalence of the different dual co-expression of SARS-CoV–2-associated proteases and receptors was optimal (100% of samples). Interestingly, only CTSL was detectable in all trophectoderm samples and a prevalence of 60% was found for the BSG-CTSL co-expression. ACE2, BSG, CTSL and CTSA were present at high expression level in CCs samples. In contrast, ACE2 and BSG expression was very low while CTSL and CTSA showed a high expression level in GCs.A prevalence of 100% was reported for ACE2-CTSL, ACE2-CTSA co-expression for both cell types. In addition, BSG-CTSL and BSG-CTSA co-expression were also present in all CCs against ∼70% in GCs samples. This data suggest a potential risks of SARS-CoV–2 infection either GC or early embryo development. Limitations, reasons for caution Analyses of Affymetrix microarray gene expression data were performed in non-COVID–19 patients. Whether the SARS-CoV–2 infection change the gene expression profile of SARS-CoV–2-associated receptors and proteases is under investigation. Wider implications of the findings: Specimens from female genital tract may be considered as potential targets for SARS-CoV–2. Trial registration number Not applicable

Study question Covid-19 pandemic has significantly affected the assisted reproductive technology (ART) practice. Understanding whether SARS-CoV-2 could infect endometrial tissues during ART is crucial for risk mitigation Summary answer Analyses of gene expression profiles of SARS-CoV-2 host entry candidates from microarray data suggest that endometrium should be considered as potential target for SARS-CoV-2 infection. What is known already Very few studies analyzed the gene expression profiles of SARS-CoV-2-associated receptors and proteases, mainly focusing on ACE2 and TMPRSS2 expression, resulting incomplete knowledge in different specimens from female genital tract. However, no studies have analyzed the potential impact of controlled ovarian stimulation (COS) protocols during ART procedure on the endometrial gene expression profiles of SARS-CoV-2-associated receptors and proteases Study design, size, duration To address this question, we retrospectively examined the gene expression profile of SARS-CoV-2-associated receptors and proteases in endometrial biopsies of a cohort of ART candidates using Affymetrix microarray data Participants/materials, setting, methods Human endometrial tissue under natural (n = 62) and COS cycles (n = 42) were analyzed. A focus was particularly made on the renin-angiotensin system relates genes with a prominent role in the virus infection, and gene expression levels of receptors and proteases closely related to SARS-CoV-2 infectionwas also studied. Main results and the role of chance Using our large cohort of endometrial samples, we reported a high prevalence of genes related to the ACE2 pathway, including AGT, AGTR1, ANPEP, CTSA, ENPEP, LNPEP, MME, NLN, THOP1, BSG and CTSL during both phases(early- and mid-secretory phase), and mainly during the mid-secretory phase for ACE2. The highest signal intensities were found for CTSA, LNPEP, MME, NLN, BSG and CTSL. The most representative of dual coexpression of SARS-CoV-2-associated receptor and protease in endometrium was BSG-CSTL and BSG-CTSA. It s also important to note high variation of SARS-CoV-2 receptors inter-patients under natural cycle.Globally, the impact of COS on endometrial gene expression profile of SARS-CoV-2-associated receptors and proteases of non Covid-19 patients is low, suggesting no additional potential risks of SARS-CoV-2 infection during stimulated ART procedure compared with natural cycles. Limitations, reasons for caution Analyses of Affymetrix microarray gene expression data were performed in non-COVID-19 patients. Whether the SARS-CoV-2 infection changes the endometrial gene expression profile of SARS-CoV-2-associated receptors and proteases is under investigation Wider implications of the findings Specimens from female genital tract may be considered as potential targets for SARS-CoV-2. Trial registration number not applicable

Oxygen (O2) concentration is approximately 5% in the fallopian tube and 2% in the uterus in humans. A “back to nature” approach could increase in vitro fertilization (IVF) outcomes. This hypothesis was tested in this monocentric observational retrospective study that included 120 couples who underwent two IVF cycles between 2014 and 2019. Embryos were cultured at 5% from day 0 (D0) to D5/6 (monophasic O2 concentration strategy) in the first IVF cycle, and at 5% O2 from D0 to D3 and 2% O2 from D3 to D5/6 (biphasic O2 concentration strategy) in the second IVF cycle. The total and usable blastocyst rates (44.4% vs. 54.8%, p = 0.049 and 21.8% vs. 32.8%, p = 0.002, respectively) and the cumulative live birth rate (17.9% vs. 44.1%, p = 0.027) were significantly higher with the biphasic (5%-2%) O2 concentration strategy. Whole transcriptome analysis of blastocysts donated for research identified 707 RNAs that were differentially expressed in function of the O2 strategy (fold-change > 2, p value 2 concentration strategy for preimplantation embryo culture could increase the “take home baby rate”, thus improving IVF cost-effectiveness and infertility management.

International audience; This is a retrospective study to evaluate if the miRNome profile of endometrium samples collected during the implantation window predicts Assisted Reproduction Technology (ART) outcomes. We first investigated the endometrial miRNome profile according to the receptivity status in 20 patients with repeated implantation failures (RIF) (discovery cohort). After customized embryo transfer, the miRNome profiles of receptive patients with a positive or negative β-hCG, and with early miscarriage or live birth were analysed. Some differentially expressed miRNAs were selected for validation by RT-qPCR in endometrial samples from 103 RIF patients (validation cohort). Analysis of the different miRNome profiles identified endometrial receptivity, implantation failure, and early miscarriage-associated miRNA signatures that included 11, 261, and 76 miRNAs, respectively. However, only four miRNAs associated with the endometrial receptivity status (miR-455-3p and miR-4423-3p) and implantation failure (miR-152-3p and miR-155-5p) were significantly validated in endometrial samples. The miRNome profile of endometrial tissues during the implantation window can predict the pregnancy outcome. These data are crucial for opening new perspectives to predict implantation failure and consequently, to increase ART success.

Objective: Covid-19 pandemic has significantly affected the assisted reproductive technology (ART) practice. Understanding whether SARS-CoV-2 could infect endometrial tissues during ART is crucial for risk mitigation. Materials and Methods: To address this question, we retrospectively examined the gene expression profile of SARS-CoV-2-associated receptors and proteases in endometrial biopsies of a cohort of ART candidates using Affymetrix microarray data. Human endometrial tissue under natural (n=62) and COS cycles (n=42) were analyzed. A focus was particularly made on the renin-angiotensin system relates genes with a prominent role in the virus infection, and gene expression levels of receptors and proteases closely related to SARS-CoV-2 infectionwas also studied. Results: Using our large cohort of endometrial samples, we reported a high prevalence of genes related to the ACE2 pathway, including AGT, AGTR1, ANPEP, CTSA, ENPEP, LNPEP, MME, NLN, THOP1, BSG and CTSL during both phases(early- and mid-secretory phase), and mainly during the mid-secretory phase for ACE2. The highest signal intensities were found for CTSA, LNPEP, MME, NLN, BSG and CTSL. The most representative of dual coexpression of SARS-CoV-2-associated receptor and protease in endometrium was BSG-CSTL and BSG-CTSA. It s also important to note high variation of SARS-CoV-2 receptors inter-patients under natural cycle.Globally, the impact of COS on endometrial gene expression profile of SARS-CoV-2-associated receptors and proteases of non Covid-19 patients is low, suggesting no additional potential risks of SARS-CoV-2 infection during stimulated ART procedure compared with natural cycles. Conclusions: Analyses of gene expression profiles ofSARS-CoV-2 host entry candidates from microarray data suggest that endometrium should be considered as potential target for SARS-CoV-2 infection. Impact Statement: Specimens from female genital tract may be considered as potential targets for SARS-CoV-2.

Objective: To determine the susceptibility of the oocytes, embryos, granulosa and cumulus cells to SARS-CoV-2 infection. Materials and Methods: To address this question, we retrospectively examined the gene expression profiles of SARS-CoV-2-associated receptors and proteases in human granulosa cells (GCs), cumulus cells (CCs), mature oocytes, day 3 embryos, blastocysts and trophectoderm cells obtained from our previously described Affymetrix microarray data from assisted reproduction patients. Human GCs and CCs (n=17), mature oocytes (n=6), and preimplantation embryos (n=20) were analyzed and gene expression levels of receptors and proteases closely related to SARS-CoV-2 infection was reported. For each gene, the number of samples with the probe set 'present', based on the detection call was studied. Each probe set was classified according to the signal intensity value median, as low ( 200). Results: ACE2, BSG, CTSL, CTSA were detectable at high expression level in all mature oocyte samples, while only CTSL was strongly expressed in all day 3 embryos. The most representative dual co-expression of SARS-CoV-2-associated receptor and protease (60% of samples) during the embryonic genome activation stage (EGA) was ACE2-CTSL and BSG-CTSL. In blastocysts, ACE2, BSG, CTSL, CTSA and FURIN were detectable in the entire cohort at high expression level, and the prevalence of the different dual co-expression of SARS-CoV-2-associated proteases and receptors was optimal (100% of samples). Interestingly, only CTSL was detectable in all trophectoderm samples and a prevalence of 60% was found for the BSG-CTSL co-expression. ACE2, BSG, CTSL and CTSA were present at high expression level in CCs samples. In contrast, ACE2 and BSG expression was very low while CTSL and CTSA showed a high expression level in GCs. A prevalence of 100% was reported for ACE2-CTSL, ACE2-CTSA co-expression for both cell types. In addition, BSG-CTSL and BSG-CTSA co-expression were also present in all CCs against ∼70% in GCs samples. This data suggests a potential risk of SARS-CoV-2 infection either GC or early embryo development. Conclusions: Transcriptomic analyses of SARS-CoV-2-associated receptors and proteases strongly suggest that blastocysts are most permissive to SARS-CoV-2 compared with mature oocytes and day 3 embryos. Impact Statement: Specimens from female genital tract may be considered as potential targets for SARS-CoV-2.

Survival and cell death signals are crucial for mammalian embryo preimplantation development. However, the knowledge on the molecular mechanisms underlying their regulation is still limited. Mouse studies are widely used to understand preimplantation embryo development, but extrapolation of these results to humans is questionable. Therefore, we wanted to analyse the global expression profiles during early mouse and human development with a special focus on genes involved in the regulation of the apoptotic and survival pathways. We used DNA microarray technology to analyse the global gene expression profiles of preimplantation human and mouse embryos (metaphase II oocytes, embryos at the embryonic genome activation stage, and blastocysts). Components of the major apoptotic and survival signalling pathways were expressed during early human and mouse embryonic development; however, most expression profiles were species-specific. Particularly, the expression of genes encoding components and regulators of the apoptotic machinery were extremely stable in mouse embryos at all analysed stages, while it was more stage-specific in human embryos.CASP3,CASP9, andAIFwere the only apoptosis-related genes expressed in both species and at all studied stages. Moreover, numerous transcripts related to the apoptotic and survival pathway were reported for the first time such asCASP6andIL1RAPL1that were specific to MII oocytes;CASP2,ENDOG, andGFERto blastocysts in human. These findings open new perspectives for the characterization and understanding of the survival and apoptotic signalling pathways that control early human and mouse embryonic development.

Repression of retrotransposons is essential for genome integrity during germ cell development and is tightly controlled through epigenetic mechanisms. In primordial germ cells, protein arginine N‐methyltransferase (Prmt5) is involved in retrotransposon repression by methylating Piwi proteins, which is part of the piRNA pathway. Here, we show that in mice, genetic inactivation of coprs (which is highly expressed in testis and encodes a histone‐binding protein required for the targeting of Prmt5 activity) affects the maturation of spermatogonia to spermatids. Mass spectrometry analysis revealed the presence of Miwi in testis protein lysates immunoprecipitated with an anti‐Coprs antibody. The observed deregulation of Miwi and pachytene pre‐piRNAs levels and the derepression of LINE1 repetitive sequences observed in coprs‐/‐ mice suggest that Coprs is implicated in genome surveillance mechanisms.

Knowledge of the global pattern of protein expression is crucial for understanding signaling pathways and biological processes that govern the acquisition of the human endometrial receptivity phenotype and for determining the possible impact of controlled ovarian stimulation (COS) during in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) procedures on endometrial receptivity. This chapter summarizes the advances on the understanding of mechanisms controlling human endometrial receptivity using high-throughput mass spectrometry-based proteomic approaches under natural and stimulated cycles. Moreover, this chapter underlines innovative and relevant noninvasive alternative approaches using proteomic data that are promising for forthcoming clinical applications to assess endometrial receptivity.

International audience; Background: Proper folliculogenesis is fundamental to obtain a competent oocyte that, once fertilized, can support the acquisition of embryo developmental competence and pregnancy. MicroRNAs (miRNAs) are crucial regulators of folliculogenesis, which are expressed in the cumulus-oocyte complex and in granulosa cells and some can also be found in the bloodstream. These circulating miRNAs are intensively studied and used as diagnostic/prognostic markers of many diseases, including gynecological and pregnancy disorders. In addition, serum contains small amounts of cell-free DNA (cfDNA), presumably resulting from the release of genetic material from apoptotic/necrotic cells. The quantification of nucleic acids in serum samples could be used as a diagnostic tool for female infertility.Methods: An overview of the published literature on miRNAs, and particularly on the use of circulating miRNAs and cfDNA as non-invasive biomarkers of gynecological diseases, was performed (up to January 2014).Results: In the past decade, cell-free nucleic acids have been studied for potential use as biomarkers in many diseases, particularly in gynecological cancers, ovarian and endometrial disorders, as well as in pregnancy-related pathologies and fetal aneuploidy. The data strongly suggest that the concentration of cell-free nucleic acids in serum from IVF patients or in embryo culture medium could be related to the ovarian hormone status and embryo quality, respectively, and be used as a non-invasive biomarker of IVF outcome.Conclusions: The profiling of circulating nucleic acids, such as miRNAs and cfDNA, opens new perspectives for the diagnosis/prognosis of ovarian disorders and for the prediction of IVF outcomes, namely (embryo quality and pregnancy).

The appreciation of endometrial receptivity is a crucial step in assisted reproductive technology as implantation failures are thought to result, in large part, from abnormal endometrial receptivity. Using emerging omics technologies, investigators have begun to define both molecular signatures and specific biomarkers of receptive endometrium. The aim of this review was to analyse the new perspectives brought to the appreciation of endometrial receptivity by transcriptomic and proteomic technologies, involving the analysis of gene- or protein-expression-profile shifts between the pre-receptive and receptive secretory stages and how they might lead to new strategies for endometrial receptivity assessments. The use of omics as molecular tools to determine the effects of stimulation protocols on endometrial gene expression and clinical outcomes has also been investigated. The appreciation of endometrial receptivity is a crucial step in assisted reproductive technology as implantation failures are thought to result, in large part, from abnormal endometrial receptivity. Using emerging omics technologies, investigators have begun to define both molecular signatures and specific biomarkers of receptive endometrium. The aim of this review is to analyse the new perspectives brought to the appreciation of endometrial receptivity by omics technologies, involving the analysis of gene- or protein-expression-profile shifts between the pre-receptive and receptive secretory stages, and how they might lead to new strategies for endometrial receptivity assessments. The use of omics during IVF procedures as molecular tools to determine the effects of stimulation protocols on endometrial gene expression and clinical outcomes has also been investigated.

International audience; In assisted reproduction, about 30% of embryo implantation failures are related to inadequate endometrial receptivity. To identify molecules involved in endometrial receptivity acquisition, we investigated, using a SELDI-TOF approach, the protein expression profile of early-secretory and mid-secretory endometrium samples. Among the proteins upregulated in mid-secretory endometrium, we investigated the function of S100A10 in endometrial receptivity and implantation process. S100A10 was expressed in epithelial and stromal cells of the endometrium of fertile patients during the implantation windows. Conversely, it was downregulated in the mid-secretory endometrium of infertile patients diagnosed as non-receptive. Transcriptome analysis of human endometrial epithelial and stromal cells where S100A10 was silenced by shRNA revealed the deregulation of 37 and 256 genes, respectively, related to components of the extracellular matrix and intercellular connections. Functional annotations of these deregulated genes highlighted alterations of the leukocyte extravasation signaling and angiogenesis pathways that play a crucial role during implantation. S100A10 silencing also affected the migration of primary endometrial epithelial and stromal cells, decidualization and secretory transformation of primary endometrial stromal cells and epithelial cells respectively, and promoted apoptosis in serum-starved endometrial epithelial cells. Our findings identify S100A10 as a player in endometrial receptivity acquisition.

The trophoblast cell lineage is specified early at the blastocyst stage, leading to the emergence of the trophectoderm and the pluripotent cells of the inner cell mass. Using a double mRNA amplification technique and a comparison with transcriptome data on pluripotent stem cells, placenta, germinal and adult tissues, we report here some essential molecular features of the human mural trophectoderm. In addition to genes known for their role in placenta (CGA, PGF, ALPPL2 and ABCG2), human trophectoderm also strongly expressed Laminins, such as LAMA1, and the GAGE Cancer/Testis genes. The very high level of ABCG2 expression in trophectoderm, 7.9-fold higher than in placenta, suggests a major role of this gene in shielding the very early embryo from xenobiotics. Several genes, including CCKBR and DNMT3L, were specifically up-regulated only in trophectoderm, indicating that the trophoblast cell lineage shares with the germinal lineage a transient burst of DNMT3L expression. A trophectoderm core transcriptional regulatory circuitry formed by 13 tightly interconnected transcription factors (CEBPA, GATA2, GATA3, GCM1, KLF5, MAFK, MSX2, MXD1, PPARD, PPARG, PPP1R13L, TFAP2C and TP63), was found to be induced in trophectoderm and maintained in placenta. The induction of this network could be recapitulated in an in vitro trophoblast differentiation model. Electronic supplementary material The online version of this article (doi:10.1007/s12015-011-9301-3) contains supplementary material, which is available to authorized users.

Background Crosstalk between human trophectoderm (TE) and endometrial cells during the implantation window is a complex and not well-understood process. The aims of this study were (i) to evaluate the global gene expression profile in TE cells from Day 5 human blastocysts issued from IVF, (ii) to compare these data with the transcriptomic profile of endometrial cells in stimulated cycles for IVF and (iii) to identify potential early dialogues between maternal and embryonic cells during the implantation window. Methods Endometrial biopsies (n = 18) from normal responder patients were performed on the day of embryo transfer (Day 5 after human chorionic gonadotrophin administration). TE biopsies from five blastocysts donated for research purposes were mechanically extracted. DNA microarray analysis was carried out to identify the specific gene expression profiles and the biological pathways activated during the implantation window in endometrial and TE cells. Results Several cytokines (such as PDGFA, placenta growth factor, IGF2BP1 and IGF2BP3) were up-regulated in human TE cells, whereas some of the corresponding receptors (PDGFRA and KDR) were over-expressed in the receptive endometrium, suggesting that these molecules are involved in the early dialogue between blastocyst and maternal endometrial cells. In addition, several adhesion molecules and extracellular matrix proteins (MCAM, ITGAE and LAMA1) were also over-expressed in the TE, while others (ALCAM, CEACAM1, PECAM1, ITGB8 and LAMA2) were restricted to the receptive endometrium. Conclusion The present study shows that several growth factors, cytokines, integrins and adhesion molecules are expressed in the TE and endometrium at the time of implantation. These results could contribute to the understanding of the mechanisms involved in the early dialogue between blastocyst and endometrium during implantation. Such results should be confirmed by further studies.

The impact of gonadotropin-releasing hormone (GnRH) agonist long compared with GnRH antagonist protocols, under in vitro fertilization conditions on endometrial receptivity, is still debated. Therefore, we compared the effect of both GnRH antagonist and agonist long protocols on the endometrial receptivity by analyzing, to our knowledge for the first time, the global gene expression profile shift during the prereceptive and receptive stages of stimulated cycles under the two GnRH analogue protocols compared with natural cycles in the same patients. For the same normal-responder patients, endometrial biopsies were collected on the day of oocyte retrieval and on the day of embryo transfer after human chorionic gonadotropin administration of a stimulated cycle with either GnRH agonist long or GnRH antagonist protocols and compared with the prereceptive and receptive stages of a natural cycle. Samples were analyzed using DNA microarrays. Gene expression profiles and biological pathways involved during the prereceptive stage to the receptive endometrial transition of stimulated and natural cycles were analyzed and compared for each patient. Both protocols affect endometrial receptivity in comparison with their natural cycle in the same patients. Major differences in endometrial chemokines and growth factors under stimulated cycles in comparison with natural cycles were observed. Such an effect has been associated with gene expression alterations of endometrial receptivity. However, the endometrial receptivity under the GnRH antagonist protocol was more similar to the natural cycle receptivity than that under the GnRH agonist protocol.

Background Recent studies suggest a role for luteinizing hormone and human chorionic gonadotrophin receptor (LH/hCGR) signalling in the regulation of the oocyte-cumulus oophorus cell interplay. The present study aimed at assessing the LH/hCGR gene expression in cumulus cells (CCs) surrounding oocytes in patients undergoing controlled ovarian hyperstimulation (COS) before ICSI and to relate the LH/hCGR expression to other COS quality parameters. Methods CCs from single oocytes of normal responder patients were analysed by DNA microarrays. Concomitantly, estradiol levels on the day of hCG administration, CC morphology, total collected oocyte and metaphase II oocyte number were assessed in relation to LH/hCGR gene expression in CC. Results The transcriptome analysis of CC indicated a variable expression of LH/hCGR among the patients and intra-patients. LH/hCGR mRNA expression was negatively correlated with serum estradiol level on the day of hCG administration. Eighty-five genes were significantly modulated between CCs from patients with a high and a low LH/hCGR expression. These genes are involved principally in steroid metabolism and in the ovulation process and include TNFAIP6, a gene expressed during CC-oocyte complex (COC) expansion. There were no significant differences in LH/hCGR gene expression profile between COS protocols. Conclusions LH/hCGR is expressed in CC under COS conditions. LH/hCGR expression level is associated with TNFAIP6 gene expression and negatively correlated with serum estradiol level on the day of hCG administration.

In assisted reproductive technology (ART), the pregnancy and birth rates following in vitro fertilization (IVF) attempts are still low. Recently, apoptotic markers have been suggested as new criteria for oocyte and embryo quality selection. Many studies have provided evidence that poor oocyte and embryo quality can be associated with apoptosis. The aim of this review is to summarize our current knowledge on the apoptotic process in oocytes and embryos, and focus on the possibility for using apoptotic markers as a reliable and predictive marker to select competent oocytes and embryos during IVF. Moreover, it is currently accepted that IVF failures, linked to poor embryo quality, are, in part, associated with suboptimal in vitro culture conditions. Here, we also review the current state of knowledge concerning how the genetic control of apoptosis during folliculogenesis and pre- implantation embryonic development is affected by in vitro culture conditions during IVF. In the future, identification of apoptotic markers in ART for oocyte and embryo selection should result in the development of new agonistic or antagonistic molecules of apoptosis by medicinal chemistry.

Identification of new criteria for embryo quality is required to improve the clinical outcome of in vitro fertilization. The aim of this study was to determine the gene expression profile of cumulus cells (CC) surrounding the oocyte as biomarkers for embryo potential and to identify genes to be used as prognostic indicators of successful pregnancy. CC from single oocytes were analysed using DNA microarrays. Gene expression profiles of CC surrounding the oocyte associated with good embryonic quality and pregnancy outcome were computed. We observed that CC issued from oocytes that developed into embryos with a good morphology had differing gene expression profile according to the pregnancy outcome of the embryo. We demonstrated that the expression of BCL2L11, PCK1 and NFIB in CC is significantly correlated with embryo potential and successful pregnancy. These results were confirmed by quantitative RT-PCR. The gene expression profiling of human CC correlates with embryo potential and pregnancy outcome. BCL2L11, PCK1 and NFIB genes are proposed as biomarkers for predicting pregnancy. Our findings suggest a non-invasive approach, offering a new potential strategy for competent embryo selection. This approach should be validated in single-embryo transfer programmes.

Background Identification of new markers assessing endometrial receptivity may help in improving the clinical outcome of IVF. This study aimed at identifying genes expressed in human endometrium during the implantation window that could be used as such markers. Methods A series of normoresponder patients (n = 31) underwent endometrial biopsies (n = 62, 2 per patient) during the early secretory phase, 2 days after the LH surge (LH + 2) and the mid-secretory phase (LH + 7) of the same natural cycle that preceded a new ICSI attempt for male infertility factor. Samples were analyzed using DNA microarrays and gene expression profiles at the time of the implantation window were computed. Systems biology analysis allowed the identification of biological pathways that were over-represented in this signature. A new approach for class prediction applied to microarray experiments was then used to identify biomarkers putatively involved in endometrial receptiveness. Results Five genes expressed during the implantation window were all up-regulated in the LH + 7 samples compared with LH + 2 [laminin beta3 (P = 0.002), microfibril-associated protein 5 (P = 0.009), angiopoietin-like 1 (P = 0.005), endocrine gland-derived vascular endothelial growth factor (P = 0.049) and nuclear localized factor 2 (P = 0.007)]. Increased expression was validated by quantitative RT-PCR. Conclusions Five genes have been identified for the first time as being up-regulated during the implantation window and are proposed as new biomarkers for exploration of endometrial receptiveness. As the endometrial biopsy procedure can be performed during a natural cycle, it would be worth testing this approach as a novel strategy in patients with poor implantation after IVF or ICSI.

In Assisted Reproductive Technology (ART), the pregnancy and birth rates following in vitro fertilization (IVF) attempts are still low. Recently, research in the field of ART has explored new oocyte and embryo quality selection criteria such as apoptotic markers. Many studies provided evidence that bad oocyte and embryo quality can be associated with apoptosis. The aim of this review is to summarize our current knowledge on the apoptosis process in oocytes and embryos, and focus on the possibility of using apoptotic markers as a reliable and predictive marker to select competent oocytes and embryos during IFV.

Apoptosis is a cell death program involved in different steps of spermatogenesis, first at puberty, at the beginning of spermatogenesis, then in adult testicles by controlling normal spermatogenesis. As a result, apoptosis deregulation can affect spermatogenesis. Many studies have provided evidence that apoptosis deregulation in germinal cells resulted in male infertility. In addition, apoptosis detection in ejaculated spermatozoa arouses a growing interest in research as a reliable marker of spermatozoon quality. The aim of this review is to summarize our knowledge on physiological apoptosis during spermatogenesis, and then analyse the possibility of using apoptotic markers as selective markers of spermatozoon quality to optimize the rate of success of in vitro fertilization.

Purpose: Few studies have investigated the endometrial receptivity status of oocyte-donation (OD) recipient patients at the specific hormone replacement therapy (HRT)-cycle timing (5 to 6 days after progesterone administration) where embryos at blastocyst stage were mostly replaced. The aim of our study was to analyse, during the implantation window, (i) the global endometrial gene expression profile, and (ii) the endometrial receptivity exploration by the Win-Test® in OD recipient patients under HRT compared to spontaneous cycle in patients awaiting for IVF.Material and methods: This study included OD recipient patients without (n=7) or with (OD RIF, n=20) repeated implantation failures and 12 normal responder patients in spontaneous cycles used as control. Endometrial biopsies were performed during the peri-implantation phase. Samples were analysed using DNA microarrays and the endometrial gene expression profiles of HRT-treated OD recipient patients and of patients in spontaneous cycles were compared. Then, specific biomarkers of endometrial receptivity were assessed in the two groups of HRT-treated OD patients in comparison to control patientsResults: The global gene expression profile of peri-implantation endometrial samples from HRT-treated OD recipients and from patients in spontaneous cycles was different with significant alterations in the oestrogen receptor signalling [GTF2H2B, POLR2B, POLR2E], VEGF family ligand-receptor interactions [VEGFR1, VEGFB] and integrin signalling [ITGAL, PAK7, ILK]. Using specific biomarkers of human endometrial receptivity, we found that endometrium was non-receptive (29 % and 43 % in OD and RIF OD patients, respectively) or partially receptive (71 and 43 % in OD and RIF OD patients, respectively), at Pg+5/+6, in majority of HRT-treated patients. In OD RIF patients, a delay of the implantation window was observed. However, by targeting personalized embryos transfer by identifying for each patient the HRT-cycle day where endometrium is receptive, with respect of the synchronization of embryo-endometrium dialogue, high pregnancy rate per frozen-thawed embryo replacement (50%) was obtained in OD RIF patients.Conclusion: This study underlines the need to take into account the individual patient’s response to HRT cycles and to move to a patient-tailored care management.

Maintenance of epithelial cell shape and polarity determines many vital cell functions, including the appropriate response to external stimuli. Murine hepatocytes cultured in a three-dimensional Matrigel matrix formed highly polarized organoids characterized by specific localization of an ERM (ezrin/radixin/moesin) protein, radixin, at microvillus-lined membrane domains. These apical domains surrounded a lumen and were bordered by tight junctions. The hepatocyte organoids were functional as judged by the high level of albumin secretion and accumulation of bilirubin. Stimulation of the Fas/CD95 death receptor, which is highly hepatotoxic in vivo, was a strong inducer of apoptosis in the polarized organoids. This was in sharp contrast to the monolayer hepatocyte cultures, which were protected from death by exacerbated NF-κB signalling following engagement of the death receptors. Thus, hepatocytes in polarized, functional organoids modulate an intracellular signal transduction pathway, allowing the recapitulation of their physiological response to an apoptotic stimulus.

Peptides corresponding to the BH3 domains of Bax (BaxBH3) or Bcl-2 (Bcl2BH3) are potent inducers of apoptosis when fused to the Atennapedia plasma membrane translocation domain (Ant). BaxBH3Ant and Bcl2BH3Ant caused a mitochondrial membrane permeabilization (MMP) and apoptosis, via a mechanism that was not inhibited by overexpressed Bcl-2 or Bcl-X(L), yet partially inhibited by cyclosporin A (CsA), an inhibitor of the mitochondrial permeability transition pore. When added to isolated mitochondria, BaxBH3 and Bcl2BH3 induced MMP, which was inhibited by CsA. However, Bcl-2 or Bcl-X(L) failed to inhibit MMP induced by BaxBH3 and Bc2BH3 in vitro, while they efficiently suppressed the induction of MMP by the Vpr protein (from human immunodeficiency virus-1), a ligand of the adenine nucleotide translocator (ANT). BaxBH3 but not Bcl2BH3 was found to interact with ANT, and only BaxBH3 (not Bcl2BH3) permeabilized ANT proteoliposomes and induced ANT to form non-specific channels in electrophysiological experiments. In contrast, both BaxBH3 and Bcl2BH3 were able to stimulate channel formation by recombinant Bax protein. Thus, BaxBH3 might induce MMP via an action on at least two targets, ANT and Bax-like proteins. In contrast, Bcl2BH3 would elicit MMP in an ANT-independent fashion. In purified mitochondria, two ligands of ANT, bongkrekic acid and the protein vMIA from cytomegalovirus, failed to prevent MMP induced by BaxBH3 or Bcl2BH3. In conclusion, BaxBH3 and Bcl2BH3 induce MMP and apoptosis through a mechanism which overcomes cytoprotection by Bcl-2 and Bcl-X(L).

Atractyloside (Atr) binds to the adenine nucleotide translocator (ANT) and inhibits ANT-mediated ATP/ADP exchange on the inner mitochondrial membrane. In addition, Atr can trigger opening of a non-specific ion channel, within the ANT-containing permeability transition pore complex (PTPC), which is subject to redox regulation and inhibited by cyclosporin A (CsA). Here we show that the cytotoxic effects of Atr, both in vivo and in vitro, are determined by its capacity to induce PTPC opening and consequent mitochondrial membrane permeabilization (MMP). Thus, the Atr-induced MMP and death of cultured liver cells are both inhibited by CsA as well as by glutathione (GSH) and enhanced by GSH depletion. Similarly, the hepatorenal toxicity of Atr, assessed in vivo, was reduced by treating mice with CsA or a diet rich in sulfur amino acids, a regime which enhances mitochondrial GSH levels. Atr injection induced MMP in hepatocytes and proximal renal tubular cells, and MMP was reduced by either CsA or GSH. Acetaminophen (paracetamol)-induced acute poisoning was also attenuated by CsA and GSH, both in vitro and in vivo. Altogether these data indicate that PTPC-mediated MMP may determine the hepatorenal toxicity of xenobiotics in vivo.