The impact of a premature elevation of serum progesterone level, the day of hCG administration in patients under controlled ovarian stimulation during IVF procedure, on human endometrial receptivity is still debated. In the present study, we investigated the endometrial gene expression profile shifts during the prereceptive and receptive secretory stage in patients with normal and elevated serum progesterone level on the day of hCG administration in fifteen patients under stimulated cycles. Then, specific biomarkers of endometrial receptivity in these two groups of patients were tested. Endometrial biopsies were performed on oocyte retrieval day and on day 3 of embryo transfer, respectively, for each patient. Samples were analysed using DNA microarrays and qRT-PCR. The endometrial gene expression shift from the prereceptive to the receptive stage was altered in patients with high serum progesterone level (>1.5 ng/mL) on hCG day, suggesting accelerated endometrial maturation during the periovulation period. This was confirmed by the functional annotation of the differentially expressed genes as it showed downregulation of cell cycle-related genes. Conversely, the profile of endometrial receptivity was comparable in both groups. Premature progesterone rise alters the endometrial gene expression shift between the prereceptive and the receptive stage but does not affect endometrial receptivity.

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 aim of this prospective study was to evaluate outcome benefits expected in repeated implantation failure (RIF) patients (n = 217) after customized embryo transfer based upon identification of the receptivity window by transcriptomic approach using the Win-Test. In this test, the expression of 11 endometrial genes known to be predictive of endometrial receptivity is assessed by RT-PCR in biopsies collected during the implantation window (6–9 days after the spontaneous luteinizing hormone surge during natural cycles, 5–9 days after progesterone administration during hormone replacement therapy cycles). Then, patients underwent either customized embryo transfer (cET, n = 157 patients) according to the Win-Test results or embryo transfer according to the classical procedure (control group, n = 60). Pregnancy and live birth rates were compared in the two groups. The Win-Test showed that in 78.5% of women, the receptivity window lasted less than 48 h, although it could be shorter (< 24 h, 9.5%) or longer (> 48 h, 12%). This highlighted that only in 20% of patients with RIF the endometrium would have been receptive if the classical embryo transfer protocol was followed. In the other 80% of patients, the receptivity window was delayed by 1–3 days relative to the classical timing. This suggests that implantation failure could be linked to inadequate timing of embryo transfer. In agreement, both implantation (22.7% vs. 7.2%) and live birth rates per patient (31.8% vs. 8.3%) were significantly higher in the cET group than in the control group. cET on the basis of the Win-Test results could be proposed to improve pregnancy and live birth rates.ClinicalTrials.gov ID: NCT04192396; December 5, 2019, retrospectively registered.

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. 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. 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. 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.

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.

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.