Prospective evaluation of uterine receptivity in mice

Exposure to urban ambient particles (PM2.5) before pregnancy affects the expression of endometrial receptive markers to embryo implantation in mice: Preliminary results

Air pollution (AP) is one of the main recent concerns in reproductive healthy due to its potential to promote negative outcomes during pregnancy and male and female fertility. Several studies have demonstrated that AP exposure has been linked to increased embryonic implantation failures, alterations in embryonic, fetal and placental development. For a well-succeeded implantation, both competent blastocyst and receptive endometrium are required. Based on the lack of data about the effect of AP in endometrial receptivity, this study aimed to evaluate he particulate matter (PM) exposure impact on uterine receptive markers in mice and associate the alterations to increased implantation failures due to AP. For this study, ten dams per group were exposed for 39 days to either filter (F) or polluted air (CAP). At fourth gestational day (GD4), females were euthanized. Morphological, ultrastructural, immunohistochemical and molecular analysis of uterine and ovarian samples were performed. CAP-exposed females presented a reduced number of corpus luteum; glands and epithelial cells were increased with pinopodes formation impairment. Immunohistochemistry analysis revealed decreased LIF protein levels. These preliminary data suggests that PM exposure may exert negative effects on endometrial receptivity by affecting crucial parameters to embryonic implantation as uterine morphological differentiation, corpus luteum quantity and LIF expression during implantation window.

Psychological Stress and Functional Endometrial Disorders: Update of Mechanism Insights

The human endometrium plays a vital role in providing the site for embryo implantation and maintaining the normal development and survival of the embryo. Recent studies have shown that stress is a common factor for the development of unexplained reproductive disorders. The nonreceptive endometrium and disturbed early maternal-fetal interaction might lead to infertility including the repeated embryo implantation failure and recurrent spontaneous abortion, or late pregnancy complications, thereby affecting the quality of life as well as the psychological status of the affected individuals. Additionally, psychological stress might also adversely affect female reproductive health. In recent years, several basic and clinical studies have tried to investigate the harm caused by psychological stress to reproductive health, however, the mechanism is still unclear. Here, we review the relationship between psychological stress and endometrial dysfunction, and its consequent effects on female infertility to provide new insights for clinical therapeutic interventions in the future.

Fine-tuned adaptation of embryo-endometrium pairs at implantation revealed by transcriptome analyses in Bos taurus

Interactions between embryo and endometrium at implantation are critical for the progression of pregnancy. These reciprocal actions involve exchange of paracrine signals that govern implantation and placentation. However, it remains unknown how these interactions between the conceptus and the endometrium are coordinated at the level of an individual pregnancy. Under the hypothesis that gene expression in endometrium is dependent on gene expression of extraembryonic tissues and genes expressed in extraembryonic tissues are dependent of genes expressed in the endometrium, we performed an integrative analysis of transcriptome profiles of paired extraembryonic tissue and endometria obtained from cattle (Bos taurus) pregnancies initiated by artificial insemination. We quantified strong dependence (|r| > 0.95, empirical false discovery rate [eFDR] < 0.01) in transcript abundance of genes expressed in the extraembryonic tissues and genes expressed in the endometrium. The profiles of connectivity revealed distinct coexpression patterns of extraembryonic tissues with caruncular and intercaruncular areas of the endometrium. Notably, a subset of highly coexpressed genes between extraembryonic tissue (n = 229) and caruncular areas of the endometrium (n = 218, r > 0.9999, eFDR < 0.001) revealed a blueprint of gene expression specific to each pregnancy. Gene ontology analyses of genes coexpressed between extraembryonic tissue and endometrium revealed significantly enriched modules with critical contribution for implantation and placentation, including “in utero embryonic development,” “placenta development,” and “regulation of transcription.” Coexpressing modules were remarkably specific to caruncular or intercaruncular areas of the endometrium. The quantitative association between genes expressed in extraembryonic tissue and endometrium emphasize a coordinated communication between these two entities in mammals. We provide evidence that implantation in mammalian pregnancy relies on the ability of the extraembryonic tissue and the endometrium to develop a fine-tuned adaptive response characteristic of each pregnancy.

An integrative analysis of interactions between conceptus and endometrium, in cattle, reveals complex regulatory networks operating at the time of implantation, highlighting the unique transcriptional blueprint of conceptus-maternal communication

Implantation in mammals requires a complex crosstalk between the conceptus (the embryo and associated membranes) and the uterus. An imbalanced regulation of the factors contributing to these interactions has negative impacts on the attachment of the fetus, the progression of the pregnancy, and the progeny. Focusing on paired conceptus–endometrium analyses of individual pregnancies in cows, we have determined that communication at implantation encompasses synchronized genome-wide coregulation of genes. Gene regulatory interactions between one conceptus and the surrounding maternal tissue vary between endometrial regions containing or lacking glands. Our data reveal new insights, to our knowledge, on the coordination of molecular mechanisms that contribute to implantation and pregnancy establishment in mammals. We conclude that the biological response of the endometrium is embryo-specific, a phenomenon that deserves further investigation in the context of assisted reproductive technologies.

Prediction of pregnancy after frozen-thawed embryo transfer via in vivo intrauterine oxidation-reduction potential measurements: a pilot study

PURPOSE

During the implantation period, the uterus goes through many complex, orchestrated changes, including alterations of the glycocalyx that are due to sialylation, sulfation, and fucosylation. A previous mouse study showed that the in vivo intrauterine oxidation-reduction potential (ORP) aided in determining the alterations in the uterine endometrium that are suitable for implantation and for evaluating prospective uterine receptivity, while the in vivo intrauterine pH did not. It was assessed if the in vivo intrauterine ORP could be a useful parameter to predict pregnancy in women.

METHODS

A prospective cohort study was conducted for patients who had received a frozen-thawed single embryo transfer in a programmed, hormonally controlled cycle. The in vivo intrauterine ORP was measured 3 times during the treatment cycle, at cycle days 9-10, 1 day before progesterone administration and immediately before the embryo transfer.

RESULTS

The amount of in vivo intrauterine ORP at 9-10 days after the start of menstrual bleeding was significantly lower in the pregnant group than in the non-pregnant group. A receiver-operator characteristic curve analysis of the intrauterine ORP as a predictor of non-conception showed an area under the curve of 0.80.

CONCLUSION

The in vivo intrauterine ORP could be a useful parameter to predict pregnancy for the frozen-thawed embryo transfer treatment cycle.