Hormonal induction of endometrial receptivity

Dietary supplementation with N-acetyl-L-cysteine ameliorates hyperactivated ERK signaling in the endometrium that is linked to poor pregnancy outcomes following ovarian stimulation in pigs

BACKGROUND

Exogenous gonadotropin-controlled ovarian stimulation is the critical step in animal reproductive management, such as pig, sheep, bovine and other species. It helps synchronize ovulation or stimulate multiple ovulations. However, a number of evidence indicated an unexpected decrease in pregnancy outcomes following ovarian stimulation. This study aimed to explore the underlying mechanism of the pregnancy defect and develop a practical rescue strategy.

RESULTS

Compared with those in the control group, gilts that underwent ovarian stimulation showed a decrease in pregnancy rate, farrowing rate, and total number of piglets born. Stimulated gilts also showed an increase in estradiol (E2) levels. The supraphysiological E2 level was correlated with the decrease in the number of piglets born. Furthermore, we found that high levels of E2 impair uterine receptivity, as shown by the overproliferation of endometrial epithelial cells. In vitro mechanistic studies demonstrated that high levels of E2 hyperactivate FGF-FGFR-ERK signaling cascade in the uterine endometrium, and in turn induces overproliferation of endometrial epithelial cells. Of note, N-acetyl-L-cysteine (NAC) supplementation effectively inhibits ERK hyperphosphorylation and ameliorates endometrial epithelial overproliferation. Importantly, in vivo experiments indicated that dietary NAC supplementation, compared with ovarian stimulation group, improves the uterine receptivity in gilts, and significantly increases the pregnancy rate and total number of piglets born.

CONCLUSIONS

Ovarian stimulation-induced supraphysiological levels of E2 impairs uterine receptivity by hyperactivating FGF-FGFR-ERK signaling cascade, thereby reducing pregnancy rate and litter size. Supplementing NAC to a conventional diet for gilts ameliorates hyperactivated ERK signaling and improves uterine receptivity, thus rescuing adverse pregnancy outcomes following ovarian stimulation.

Rapid increase of MFGE8 secretion from endometrial epithelial cells is an indicator of extracellular vesicle mediated embryo maternal dialogue

Successful embryo implantation relies on synchronized dialog between the embryo and endometrium, and the role of extracellular vesicles (EVs) in facilitating this cross-talk has been recently established. In our previous study, milk fat globule-EGF factor 8 protein (MFGE8) was identified as increasing in receptive endometrial epithelial cells (EECs) in response to trophoblastic EVs. However, the dynamics of MFGE8 protein in this context are not completely understood. Therefore, we examined its expression and secretion in EECs exposed to estrogen, progesterone, and trophoblastic EVs to gain deeper insights into its potential as an indicator of EV-mediated embryo-maternal dialogue. Our findings revealed that MFGE8 secretion is sensitive to estrogen and progesterone, and that trophoblastic EVs stimulate their release in both receptive and non-receptive EECs. Furthermore, trophoblast EV function was dose and time-dependent. Notably, the secretion of MFGE8 increased within a short timeframe of 30 min after addition of EVs, suggesting the possibility of rapid processes such as binding, fusion or internalization of trophoblastic EVs within EECs. Interestingly, MFGE8 released from EECs was associated with EVs, suggesting increased EV secretion from EECs in response to embryonic signals. In conclusion, increased MFGE8 secretion in this embryo implantation model can serve as an indicator of EV-mediated embryo-maternal dialogue.

Molecular Determinants of Uterine Receptivity: Comparison of Successful Implantation, Recurrent Miscarriage, and Recurrent Implantation Failure

Embryo implantation is one of the most remarkable phenomena in human reproduction and is not yet fully understood. Proper endometrial function as well as a dynamic interaction between the endometrium itself and the blastocyst-the so-called embryo-maternal dialog-are necessary for successful implantation. Several physiological and molecular processes are involved in the success of implantation. This review describes estrogen, progesterone and their receptors, as well as the role of the cytokines interleukin (IL)-6, IL-8, leukemia inhibitory factor (LIF), IL-11, IL-1, and the glycoprotein glycodelin in successful implantation, in cases of recurrent implantation failure (RIF) and in cases of recurrent pregnancy loss (RPL). Are there differences at the molecular level underlying RIF or RPL? Since implantation has already taken place in the case of RPL, it is conceivable that different molecular biological baseline situations underlie the respective problems.

Advanced maternal age leads to changes within the insulin/IGF system and lipid metabolism in the reproductive tract and preimplantation embryo: insights from the rabbit model

Reproductive potential in women declines with age. The impact of ageing on embryo-maternal interactions is still unclear. Rabbits were used as a reproductive model to investigate maternal age-related alterations in reproductive organs and embryos on Day 6 of pregnancy. Blood, ovaries, endometrium, and blastocysts from young (16-20 weeks) and advanced maternal age phase (>108 weeks, old) rabbits were analysed at the mRNA and protein levels to investigate the insulin-like growth factor (IGF) system, lipid metabolism, and stress defence system. Older rabbits had lower numbers of embryos at Day 6 of pregnancy. Plasma insulin and IGF levels were reduced, which was accompanied by paracrine regulation of IGFs and their receptors in ovaries and endometrium. Embryos adapted to hormonal changes as indicated by reduced embryonic IGF1 and 2 levels. Aged reproductive organs increased energy generation from the degradation of fatty acids, leading to higher oxidative stress. Stress markers, including catalase, superoxide dismutase 2, and receptor for advanced glycation end products were elevated in ovaries and endometrium from aged rabbits. Embryonic fatty acid uptake and β-oxidation were increased in both embryonic compartments (embryoblast and trophoblast) in old rabbits, associated with minor changes in the oxidative and glycative stress defence systems. In summary, the insulin/IGF system, lipid metabolism, and stress defence were dysregulated in reproductive tissues of older rabbits, which is consistent with changes in embryonic metabolism and stress defence. These data highlight the crucial influence of maternal age on uterine adaptability and embryo development.

Estradiol on trigger day: Irrelevant to live birth rates of fresh cycles but positively associated with cumulative live birth rates

OBJECTIVE

To assess the effects of estradiol (E2) on trigger day on cumulative live birth rates (CLBRs), and pregnancy outcomes after fresh and frozen-thawed embryo transfer (FET).

METHODS

This multicenter retrospective cohort study included 42 315 patients from five reproductive centers. Six subgroups were divided according to E2 on trigger day (<1000, 1000-2000, 2000-3000, 3000-4000, 4000-5000, >5000 pg/mL). Smooth curve fitting and nonlinear mixed-effects models were used.

RESULTS

When E2 was <5500 pg/mL, the CLBR increased by 10% for every 1000 pg/mL increase in E2. When E2 was between 5500 and 13 281 pg/mL, CLBR increased by 1.8% for every 1000 pg/mL increase in E2. When E2 was >13 281 pg/mL, CLBR decreased by 3% for every 1000 pg/mL increase in E2. From group E2 < 1000 to group E2 > 5000 pg/mL, pregnancy and live birth rates in fresh cycles were not related to E2. The live birth rate after FET was higher in the E2 ≥ 5000 pg/mL group than in the E2 < 1000 pg/mL group (odds ratio [OR] 4.03, and 95% confidence interval [CI] 3.74-4.35; adjusted OR 1.20, 95% CI 1.05-1.37).

CONCLUSION

CLBR is associated with E2 on trigger day in a segmented manner. Pregnancy and live birth rates in fresh cycles were not associated with E2. The live birth rate in FET cycles was highest when E2 ≥ 5000 pg/mL.

Adding a ketogenic dietary intervention to IVF treatment in patients with polycystic ovary syndrome improves implantation and pregnancy

Patients with polycystic ovary syndrome (PCOS) on a high-carbohydrate diet intrinsically suffer from exacerbated glucotoxicity, insulin resistance (IR), and infertility. Lowering the carbohydrate content has improved fertility in patients with IR and PCOS; however, the effects of a well-controlled ketogenic diet on IR and fertility in PCOS patients undergoing in vitro fertilization (IVF) have not been reported. Twelve PCOS patients with a previous failed IVF cycle and positive for IR (HOMA1-IR>1.96) were retrospectively evaluated. Patients followed a ketogenic diet (50 g of total carbohydrates/1800 calories/day). Ketosis was considered when urinary concentrations were > 40 mg/dL. Once ketosis was achieved, and IR diminished, patients underwent another IVF cycle. The nutritional intervention lasted for 14 ± 11 weeks. Carbohydrate consumption decreased from 208 ± 50.5 g/day to 41.71 ± 10.1 g/day, which resulted in significant weight loss (-7.9 ± 1.1 kg). Urine ketones appeared in most patients within 13.4 ± 8.1 days. In addition, there was a decrease in fasting glucose (-11.4 ± 3.5 mg/dl), triglycerides (-43.8 ± 11.6 mg/dl), fasting insulin (-11.6 ± 3.7 mIU/mL), and HOMA-IR (-3.28 ± 1.27). All patients underwent ovarian stimulation, and compared to the previous cycle, there was no difference in oocyte number, fertilization rate, and viable embryos produced. However, there was a significant improvement in the implantation (83.3 vs. 8.3 %), clinical pregnancy (66.7 vs. 0 %), and ongoing pregnancy/live birth rates (66.7 vs. 0 %). Here, restriction in carbohydrate consumption in PCOS patients induced ketosis, improved key metabolic parameters, and decreased IR. Even though this did not affect oocyte or embryo quality or quantity, the subsequent IVF cycle significantly improved embryo implantation and pregnancy rates.

Preparation of the endometrium for frozen embryo transfer: an update on clinical practices

Over the past decade, the application of frozen-thawed embryo transfer treatment cycles has increased substantially. Hormone replacement therapy and the natural cycle are two popular methods for preparing the endometrium. Hormone replacement therapy is now used at the discretion of the doctors because it is easy to coordinate the timing of embryo thawing and transfer with the schedules of the in-vitro fertilization lab, the treating doctors, and the patient. However, current results suggest that establishing a pregnancy in the absence of a corpus luteum as a result of anovulation may pose significant maternal and fetal risks. Therefore, a 'back to nature' approach that advocates an expanded use of natural cycle FET in ovulatory women has been suggested. Currently, there is increasing interest in how the method of endometrial preparation may influence frozen embryo transfer outcomes specifically, especially when it comes to details such as different types of ovulation monitoring and different luteal support in natural cycles, and the ideal exogenous hormone administration route as well as the endocrine monitoring in hormone replacement cycles. In addition to improving implantation rates and ensuring the safety of the fetus, addressing these points will allow for individualized endometrial preparation, also as few cycles as possible would be canceled.

Agonist long protocol improves outcomes of vitrified-warmed embryo transfer in repeatedly thin endometrium

RESEARCH QUESTION

Does follicular stimulation using human menopausal gonadotrophin (HMG) after pituitary down-regulation by a GnRH agonist improve endometrial thickness (EMT) and clinical outcomes of frozen-thawed embryo transfer (FET; using vitrified-warmed embryos) in women with thin endometrium after intensified oestrogen administration (IOA)?

DESIGN

This was a retrospective study. A total of 627 patients attempted 683 FET cycles with at least one previous history of thin endometrium. None of the cycles reached over 7 mm EMT after using oral and vaginal oestradiol for more than 21 days (IOA protocol). A total of 129 cycles proceeded with FET, 305 cycles were cancelled, and 249 cycles involved administration of HMG following GnRH agonist pituitary down-regulation (GnRH agonist + HMG protocol) for further endometrial preparation.

RESULTS

EMT became significantly greater (7.18 ± 1.14 mm versus 6.13 ± 0.63 mm, P < 0.001) using GnRH agonist + HMG compared with previous IOA cycles, but this was not related to serum oestrogen concentrations. A total of 213 cycles after the GnRH agonist + HMG protocol proceeded with FET, showing a significantly increased clinical pregnancy rate, implantation rate and live birth rate compared with those after IOA.

CONCLUSIONS

The GnRH agonist + HMG protocol for endometrial preparation in FET cycles improves EMT in women with a thin endometrium after IOA and showed significantly better clinical outcomes than IOA. The authors suggest that the GnRH agonist + HMG protocol should be used for EMT that is less than 7 mm after there has been no optimal response to IOA.

Impact of an estrogen replacement regimen on live birth rate in frozen-thawed good-quality embryo transfer

OBJECTIVE

To assess the impact of an estrogen replacement regimen on frozen embryo transfer (FET) cycle outcome.

METHODS

In the present retrospective cohort study, data of infertile women undergoing FET with good-quality embryos were reviewed. The first group received 2 mg of estradiol hemihydrate (EH) once daily for 6 to 7 days, then twice daily for 4 to 5 days, and then three times a day until embryo transfer. The second group received EH twice daily for 7 to 8 days, then three times a day. The third group received EH three times a day constantly. The main outcome measure was live birth rate.

RESULTS

In total, 394 FET cycles were included. The fixed 6-mg group required the highest estradiol hemihydrate dose. The duration of estrogen treatment was significantly longer in the first group. Maximal endometrial thickness was highest in the second group (10.2 ± 1.3 mm vs. 9.6 ± 1.4 mm vs. 8.6 ± 0.9 mm, respectively; P < 0.001). The clinical pregnancy rates in the groups were 41.1%, 55.2%, and 42.2%, respectively (P = 0.035). Live birth rates were 40.8%, 50.9%, and 48.1%, respectively (P = 0.320).

CONCLUSION

In FET cycles with hormone replacement therapy, a step-up 4-mg regimen provides thicker endometrium with optimal-dose estrogen in an adequate time frame. The tendency for increased clinical pregnancy and live birth rates is remarkable.

Adverse effect of assisted reproductive technology-related hyperoestrogensim on the secretion and absorption of uterine fluid in superovulating mice during the peri-implantation period

OBJECTIVES

This study aimed to investigate the potential mechanism of hyperoestrogensim elicited by ovulation induction affects endometrial receptivity and leads to embryo implantation abnormality or failure.

STUDY DESIGN

Establishment of ovulation induction mouse model. Changes in mouse body weight, ovarian weight, serum E2 level and oestrous cycle were observed. During the peri-implantation period, morphological changes in the mouse uterus and implantation sites and the localization and protein levels of oestrogen receptors ERα and ERβ, the tight junction factors CLDN3 and OCLN, the aquaporins AQP3, AQP4 and AQP8, and the sodium channel proteins SCNN1α, SCNN1β and SCNN1γ were observed. The expression and cellular localization of ERα, CLDN3, AQP8 and SCNN1 β in RL95-2 cell line were also detected by western blotting and immunofluorescence.

RESULTS

Ovarian and body weights were significantly higher in the 5 IU and 10 IU groups than in the CON group. The E2 level was significantly higher in the 10 IU group than in the CON group. The mice in the 10 IU group had a disordered oestrous cycle and were in oestrus for a long time. At 5.5 dpc, significantly fewer implantation sites were observed in the 10 IU group than in the CON (p<0.001) and 5 IU (p<0.05) groups. The probability of abnormal implantation and abortion was higher in the 10 IU group than in the CON and 5 IU groups. CLDN3, OCLN, AQP8 and SCNN1β in the mouse endometrium were localized on the luminal epithelium and glandular epithelium and expression levels were lower in the 10 IU group than in the CON group. The protein expression level of ERα was increased by 50% in the 10 IU group compared to the CON group. The expressions of CLDN3, AQP8, SCNN1β in RL95-2 cell line were significantly depressed by the superphysiological E2, ERα agonist or ERβ agonist, which could be reversed by the oestrogen receptor antagonist.

CONCLUSION

ART-induced hyperoestrogenism reduces CLDN3, AQP8 and SCNN1β expression through ERα, thereby destroying tight junctions and water and sodium channels in the endometrial cavity epithelium, which may cause abnormal implantation due to abnormal uterine fluid secretion and absorption.

Elevated estradiol levels in frozen embryo transfer have different effects on pregnancy outcomes depending on the stage of transferred embryos

Supplementation with estradiol (E2) is routinely used in frozen embryo transfer (FET) cycles and embryo age plays an important role in conceiving. This study was to compare the effects of serum E2 levels on pregnancy outcomes between cleavage- and blastocyst-stage FET cycles using hormone replacement therapy. A total of 776 FET cycles (669 couples) performed from January 2016 to December 2019 were included in the present retrospective cohort study. Regarding cleavage-stage embryo transfers, E2 levels on progesterone initiation day were significantly lower in the ongoing pregnancy/live birth (OP/LB) group than in the non-OP/LB group (214.75 ± 173.47 vs. 253.20 ± 203.30 pg/ml; P = 0.023). In addition, there were downward trends in implantation, clinical pregnancy and OP/LB rates with increasing E2 levels. However, in blastocyst-stage embryo transfers, such trends were not observed, and E2 levels were not significant difference between the OP/LB group and the non-OP/LB group (201.66 ± 182.14 vs. 197.89 ± 212.83 pg/ml; P = 0.884). The results suggests that elevated progesterone-initiation-day E2 levels may negatively affect pregnancy outcomes during artificial cleavage-stage embryo transfers. However, it is not necessary to monitor E2 levels when transferring blastocysts in artificial FET cycles.

Oral dydrogesterone in frozen-thawed embryo transfer cycles

OBJECTIVE

The aim of this study was to compare the use of micronized vaginal progesterone and oral dydrogesterone in the endometrial preparation for frozen-thawed embryo transfer.

METHODS

This was a randomized, controlled, open, two-armed clinical trial, with women undergoing frozen-thawed embryo transfer along with hormone replacement therapy for endometrial preparation, between September 2019 and February 2021. A total of 73 patients were randomly selected and orally administered 40 mg/day dydrogesterone (dydrogesterone group, n=36) or 800 mg/day micronized vaginal progesterone (micronized vaginal progesterone group, n=37), after endometrial preparation with transdermal estradiol. The main outcome was a viable ongoing pregnancy with 12 weeks of gestation as evaluated by ultrasound.

RESULTS

The reproductive outcomes in frozen-thawed embryo transfer cycles were similar, with pregnancy rates in the dydrogesterone and micronized vaginal progesterone treatment groups being, respectively, 33.3 and 32.4% at 12 weeks pregnancy (confidence interval= -22.4-20.6, p=0.196).

CONCLUSIONS

The use of oral dydrogesterone may be a more patient-friendly approach to endometrial preparation in frozen-thawed embryo transfer cycles, avoiding undesirable side effects and discomfort resulting from vaginal administration, while also providing similar reproductive results.

"Does serum estrogen level have an impact on outcomes in hormonal replacement frozen-warmed embryo transfer cycles?"

AIM

To evaluate the impact of serum estradiol (E2) levels on cycle outcomes in hormone replacement frozen embryo transfer (HR- FET) cycles.

MATERIALS AND METHODS

We retrospectively analyzed 509 HR-FET cycles performed from September 2018 to September 2019. Patients were divided into 6 groups based on their E2 values measured a day before progesterone initiation . Group 1: <100 pg/mL, group 2: 100-200 pg/mL, group 3: 200 - 300 pg/mL, group 4: 300-400 pg/mL, group 5: 400-500 pg/mL, group 6: >500 pg/mL. Implantation rate (IR), clinical pregnancy rate (CPR), miscarriage rate (MR), multiple pregnancy rate (MPR) and ectopic pregnancy rates were compared between all groups.

RESULTS

IR and CPR were similar between a wide range of E2 values, but when E2 values were more than 500 pg/mL there was a non significant fall in the IR (47.3% vs 48.3% vs 48.6% vs 47.8% vs 48.7% vs 39.6% p = .77) and CPR (63.6% vs 65.1% vs 65.6% vs 65.3% vs 65.6% vs 53.1% p = .692). MR was significantly high when E2 was less than 100 pg/mL (28.5%) and when E2 was more than 500 pg/mL (41.1%) (p = .02). MPR and ectopic pregnancy rates were similar between all the groups.

CONCLUSION

Outcomes of FET cycles were similar between a wide range of E2 values (100-500 pg/mL). When E2 levels were less than 100 pg/mL or more than 500 pg/mL there was significant increase in the MR but the numbers in these groups are less and further studies are required to confirm these facts.

Duration of estradiol supplementation in luteal phase support for frozen embryo transfer in hormone replacement treatment cycles: a randomized, controlled phase III trial

PURPOSE

In this study, we intend to evaluate pregnancy outcomes in women who undergo artificial frozen embryo transfer (FET) and stop estradiol (E2) after vaginal ultrasound observation of a gestational sac and heartbeat.

METHODS

In this randomized phase III clinical trial, we recruited 291 patients who underwent FET. We randomly assigned 64 pregnant women to a study or a control group after observation of a gestational sac and heartbeat at 6-week gestational age. E2 administration continued until week 12 of gestational age for the control group, but was discontinued for the study group. Progesterone-in-oil administration continued until week 12 of gestational age for both groups. Serum levels for E2 and progesterone were measured on the initial progesterone and embryo transfer (ET) days, and at weeks 6 and 12 of pregnancy in both groups.

RESULTS

The miscarriage rate was 1/32 (3.13%) in the study group and 6/32 (18.75%) in the control group after the intervention and confirmation of a fetal heartbeat. This difference was statistically significant. All patients who remained under intervention, which included 29 in the study group and 24 in the control group, had live births. Although the mean serum E2 and progesterone levels steadily increased from the initial day of progesterone administration to week 12 of gestational age, they were not significantly different between the two groups. Maternal complications were significantly more common in the control group.

CONCLUSION

Earlier discontinuation of E2 for luteal phase support of FET cycles may be taken into consideration. Additional clinical studies should be conducted to determine an accurate estimation of the time when E2 should be discontinued during FET luteal phase support.

TRIAL REGISTRATION

NCT04013438, registered 9 July 2019-Retrospectively registered, https://www.clinicaltrials.gov/ct2/show/NCT04013438?cond=NCT04013438&draw=2&rank=1.

A 3D endometrial organotypic model simulating the acute inflammatory decidualisation initiation phase with epithelial induction of the key endometrial receptivity marker, integrin αVβ3

STUDY QUESTION

Is it possible to develop a simplified physiological in vitro system representing the key cell-types associated with a receptive endometrial phenotype?

SUMMARY ANSWER

We present a new concept to investigate endometrial receptivity, with a 3D organotypic co-culture model to simulate an early and transient acute autoinflammatory decidual status that resolves in the induction of a receptive endometrial phenotype.

WHAT IS KNOWN ALREADY

Embryo implantation is dependent on a receptive uterine environment. Ovarian steroids drive post-ovulation structural and functional changes in the endometrium, which becomes transiently receptive for an implanting conceptus, termed the ‘window of implantation’, and dysregulation of endometrial receptivity is implicated in a range of reproductive, obstetric, and gynaecological disorders and malignancies. The interactions that take place within the uterine microenvironment during this time are not fully understood, and human studies are constrained by a lack of access to uterine tissue from specific time-points during the menstrual cycle. Physiologically relevant in vitro model systems are therefore fundamental for conducting investigations to better understand the cellular and molecular mechanisms controlling endometrial receptivity.

STUDY DESIGN, SIZE, DURATION

We conducted an in vitro cell culture study using human cell lines and primary human cells isolated from endometrial biopsy tissue. The biopsy tissue samples were obtained from three women attending gynaecological outpatient departments in NHS Lothian. The work was carried out between December 2016 and April 2019, at the MRC Centre for Reproductive Health, Queen’s Medical Research Institute, University of Edinburgh.

PARTICIPANTS/MATERIALS, SETTING, METHODS

An endometrial stromal cell (ESC) line, and endometrial epithelial cells (EECs) isolated from endometrial biopsy tissue and expanded in vitro by conditional reprogramming, were used throughout the study. Immunocytochemical and flow cytometric analyses were used to confirm epithelial phenotype following conditional reprogramming of EECs. To construct an endometrial organotypic co-culture model, ESCs were embedded within a 3D growth factor-reduced Matrigel structure, with a single layer of conditionally reprogrammed EECs seeded on top. Cells were stimulated with increasing doses of medroxyprogesterone acetate, cAMP and oestradiol, in order to induce ESC decidual transformation and endometrial receptivity. Decidual response and the induction of a receptive epithelial phenotype were assessed by immunocytochemical detection and quantitative in-cell western analyses, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

A transient up-regulation of the interleukin-33 receptor protein, ST2L, was observed in ESCs, indicating a transient autoinflammatory decidual response to the hormonal stimulation, known to induce receptivity gene expression in the overlying epithelium. Hormonal stimulation increased the EEC protein levels of the key marker of endometrial receptivity, integrin αVβ3 (n = 8; *P < 0.05; ***P < 0.0001). To our knowledge, this is the first demonstration of a dedicated endometrial organotypic model, which has been developed to investigate endometrial receptivity, via the recapitulation of an early decidual transitory acute autoinflammatory phase and induction of an epithelial phenotypic change, to represent a receptive endometrial status.

LIMITATIONS, REASONS FOR CAUTION

This simplified in vitro ESC-EEC co-culture system may be only partly representative of more complex in vivo conditions.

WIDER IMPLICATIONS OF THE FINDINGS

The 3D endometrial organotypic model presented here may offer a valuable tool for investigating a range of reproductive, obstetric, and gynaecological disorders, to improve outcomes for assisted reproductive technologies, and for the development of advances in contraceptive methods.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported in part by a Medical Research Council Centre Grant (project reference MR/N022556/1). R.F. was the recipient of a Moray Endowment award and a Barbour Watson Trust award. C.-J.L. is a Royal Society of Edinburgh Personal Research Fellow, funded by the Scottish Government. The authors have no conflicts of interest to declare.

Preparation of the Endometrium for Frozen Embryo Transfer: A Systematic Review

Despite the worldwide increase in frozen embryo transfer, the search for the best protocol to prime endometrium continues. Well-designed trials comparing various frozen embryo transfer protocols in terms of live birth rates, maternal, obstetric and neonatal outcome are urgently required. Currently, low-quality evidence indicates that, natural cycle, either true natural cycle or modified natural cycle, is superior to hormone replacement treatment protocol. Regarding warmed blastocyst transfer and frozen embryo transfer timing, the evidence suggests the 6th day of progesterone start, LH surge+6 day and hCG+7 day in hormone replacement treatment, true natural cycle and modified natural cycle protocols, respectively. Time corrections, due to inter-personal differences in the window of implantation or day of vitrification (day 5 or 6), should be explored further. Recently available evidence clearly indicates that, in hormone replacement treatment and natural cycles, there might be marked inter-personal variation in serum progesterone levels with an impact on reproductive outcomes, despite the use of the same dose and route of progesterone administration. The place of progesterone rescue protocols in patients with low serum progesterone levels one day prior to warmed blastocyst transfer in hormone replacement treatment and natural cycles is likely to be intensively explored in near future.

Screening of Variants in the Transcript Profile of Eutopic Endometrium from Infertile Women with Endometriosis during the Implantation Window

OBJECTIVE

 Abnormalities in the eutopic endometrium of women with endometriosis may be related to disease-associated infertility. Although previous RNA-sequencing analysis did not show differential expression in endometrial transcripts of endometriosis patients, other molecular alterations could impact protein synthesis and endometrial receptivity. Our aim was to screen for functional mutations in the transcripts of eutopic endometria of infertile women with endometriosis and controls during the implantation window.

METHODS

 Data from RNA-Sequencing of endometrial biopsies collected during the implantation window from 17 patients (6 infertile women with endometriosis, 6 infertile controls, 5 fertile controls) were analyzed for variant discovery and identification of functional mutations. A targeted study of the alterations found was performed to understand the data into disease's context.

RESULTS

 None of the variants identified was common to other samples within the same group, and no mutation was repeated among patients with endometriosis, infertile and fertile controls. In the endometriosis group, nine predicted deleterious mutations were identified, but only one was previously associated to a clinical condition with no endometrial impact. When crossing the mutated genes with the descriptors endometriosis and/or endometrium, the gene CMKLR1 was associated either with inflammatory response in endometriosis or with endometrial processes for pregnancy establishment.

CONCLUSION

 Despite no pattern of mutation having been found, we ponder the small sample size and the analysis on RNA-sequencing data. Considering the purpose of the study of screening and the importance of the CMKLR1 gene on endometrial modulation, it could be a candidate gene for powered further studies evaluating mutations in eutopic endometria from endometriosis patients.

Association between serum estradiol levels prior to progesterone administration in artificial frozen-thawed blastocyst transfer cycles and live birth rate: a retrospective study

OBJECTIVE

To study whether serum estradiol (E2) levels prior to progesterone administration in the artificial endometrial preparation (AEP) of frozen-thawed blastocyst transfer affect the live birth rate.

DESIGN

Retrospective cohort study.

SETTING

Tertiary-care academic medical centre.

POPULATION

A total of 3857 frozen-thawed blastocyst transfer cycles were divided into three groups: <200 pg/ml (n = 1676); 200-399 pg/ml (n = 1296); and ≥400 pg/ml (n = 885), based on the 25th (182.3 pg/ml) and 75th percentile (390.2 pg/ml) of serum E2 level prior to progesterone administration.

METHODS

Univariable and multivariable logistic regression analysis was performed.

MAIN OUTCOME MEASURES

The primary outcome of the study was the live birth rate and the secondary outcomes included clinical pregnancy rate, pregnancy loss rate, neonatal birthweight, Z-score, and small for gestational age (SGA).

RESULTS

Compared with the reference group, accounting for major covariates, the live birth rate significantly decreased in the '≥400 pg/ml' group (adjusted OR 0.71, 95% CI 0.59-0.85). Compared with the reference group, there was an association between the E2 level in the '≥400 pg/ml' group and a decrease in the clinical pregnancy rate (adjusted OR 0.74, 95% CI 0.61-0.89). Compared with the reference group, the pregnancy loss rate significantly increased in the '≥400 pg/ml' group (adjusted OR 1.45, 95% CI 1.08-1.93). The E2 levels did not affect neonatal birthweight, Z-score, and SGA among singletons.

CONCLUSIONS

High serum E2 levels prior to progesterone administration in AEP are associated with a decreased live birth rate after frozen-thawed blastocyst transfer.

TWEETABLE ABSTRACT

High serum E2 levels prior to progesterone administration in artificial FET are associated with a decreased live birth rate after frozen-thawed blastocyst transfer.

The use of propensity score matching to assess the benefit of the endometrial receptivity analysis in frozen embryo transfers

OBJECTIVE

To study the impact of the endometrial receptivity analysis (ERA) on live birth rates in frozen embryo transfer (FET) cycles.

DESIGN

Retrospective cohort study.

SETTING

A single, large, university-affiliated infertility practice.

PATIENT(S)

Autologous FET cycles between January 1, 2014, and June 30, 2019, were reviewed. Multiple covariates that impact outcomes were used for propensity score matching; 133 ERA patients were matched to 353 non-ERA patients. Patients were assigned to the ERA group if they had an ERA during treatment and underwent at least one "personalized" FET based on the ERA recommendations.

INTERVENTION(S)

No interventions administered.

MAIN OUTCOME MEASURE(S)

Live birth rates per cycle in the FET cycle after ERA compared with that of matched non-ERA patients.

RESULT(S)

The live birth rates for the ERA group, 49.62%, and the matched non-ERA group, 54.96%, (odds ratio 0.8074; 95% confidence interval, 0.5424-1.2018) were not significantly different, nor was a difference seen in subanalyses based on prior number of FETs or receptivity status.

CONCLUSION(S)

The ERA identifies a patient's putative window of implantation with the goal of improving synchrony with the embryo, thereby achieving higher live birth rates. This study used propensity score matching to control for multiple covariates in a heterogenous group of patients to compare live birth rates. There was no difference in the live birth rate in patients who underwent the ERA compared with that of those who did not.

Stimulated cycle versus artificial cycle for frozen embryo transfer in patients with polycystic ovary syndrome: a Meta-analysis

PURPOSE

Our aim is to conduct a meta-analysis comparing clinical outcomes between the mild ovarian stimulation cycle versus an artificial cycle (AC) for frozen embryo transfer (FET) in patients with polycystic ovary syndrome (PCOS).

METHODS

We systematically searched the databases of PubMed, EMBASE and the Cochrane Library from inception to January 2020. The outcomes were live birth rate (LBR), ongoing pregnancy rate (OPR), clinical pregnancy rate (CPR), embryo implantation rate (IR) and miscarriage rate (MR). The mild ovarian stimulation cycle and AC were compared according to risk ratios and 95% confidence intervals using a fixed or random effects model.

RESULTS

Four retrospective studies describing the clinical outcomes were included. We found no significant difference in LBR, OPR, CPR, IR or MR between the mild ovarian stimulation cycle and AC protocols, whereas a lower MR was found for the letrozole-stimulated cycle than the AC.

CONCLUSIONS

The letrozole-stimulated cycle for endometrial preparation in PCOS patients undergoing FET may lower the MR more than the AC. PCOS patients using the mild ovarian stimulation cycle for endometrial preparation undergoing FET had similar LBR, OPR, CPR and IR compared with the AC. The letrozole-stimulated protocol may be a reasonable choice for endometrial preparation before FET for women with PCOS.

Effect of transdermal estrogen dose regimen for endometrial preparation of frozen-thawed embryo transfer on reproductive and obstetric outcomes

PURPOSE

Previous studies have reported different methods of estrogen administration during endometrial preparation for frozen-thawed embryo transfer (FET). This study aimed to investigate a beneficial regimen of transdermal estrogen administration for FET.

METHODS

We investigated the reproductive and obstetric outcomes of FET by comparing the increasing dose (ID) group that mimics changes in serum estradiol during the menstrual cycle and the constant dose (CD) group. Transdermal patches were used for estrogen administration in both groups. In our hospital, we targeted 315 cycles of the ID group in which FET was performed in 2017 and 324 cycles of the CD group in which FET was performed in 2018. In all cases, single embryo transfer was performed.

RESULTS

All were singleton pregnancies. There was no difference in clinical pregnancy rate (28.9% vs 28.2%, P =.837) and live birth rate (17.3% vs 21.4%, P =.201) between the ID and CD groups. Spontaneous abortion rate was significantly lower in the CD group than in the ID group (37.2% vs 23.0%, P =.041). There was no difference in obstetrical outcomes.

CONCLUSIONS

It was considered that the simple CD regimen may be more beneficial than the complicated ID regimen.

CXCL12 enhances pregnancy outcome via improvement of endometrial receptivity in mice

Successful pregnancy inevitably depends on the implantation of a competent embryo into a receptive endometrium. Although many substances have been suggested to improve the rate of embryo implantation targeting enhancement of endometrial receptivity, currently there rarely are effective evidence-based treatments to prevent or cure this condition. Here we strongly suggest minimally-invasive intra-uterine administration of embryo-secreted chemokine CXCL12 as an effective therapeutic intervention. Chemokine CXCL12 derived from pre- and peri-implanting embryos significantly enhances the rates of embryo attachment and promoted endothelial vessel formation and sprouting in vitro. Consistently, intra-uterine CXCL12 administration in C57BL/6 mice improved endometrial receptivity showing increased integrin β3 and its ligand osteopontin, and induced endometrial angiogenesis displaying increased numbers of vessel formation near the lining of endometrial epithelial layer with higher CD31 and CD34 expression. Furthermore, intra-uterine CXCL12 application dramatically promoted the rates of embryo implantation with no morphologically retarded embryos. Thus, our present study provides a novel evidence that improved uterine endometrial receptivity and enhanced angiogenesis induced by embryo-derived chemokine CXCL12 may aid to develop a minimally-invasive therapeutic strategy for clinical treatment or supplement for the patients with repeated implantation failure with less risk.

The exact synchronization timing between the cleavage embryo stage and duration of progesterone therapy-improved pregnancy rates in frozen embryo transfer cycles: A cross-sectional study

Background

Synchronization between the embryonic stage and the uterine endometrial lining is important in the outcomes of the vitrified-warmed embryo transfer (ET) cycles.

Objective

The aim was to investigate the effect of the exact synchronization between the cleavage stage of embryos and the duration of progesterone administration on the improvement of clinical outcomes in frozen embryo transfer (FET) cycles.

Materials and Methods

312 FET cycles were categorized into two groups: (A) day-3 ET after three days of progesterone administration (n = 177) and (B) day-2 or -4 ET after three days of progesterone administration (n = 135). Group B was further divided into two subgroups: B1: day-2 ET cycles, that the stage of embryos were less than the administrated progesterone and B2: day-4 ET cycles, that the stage of embryos were more than the administrated progesterone. The clinical outcome measures were compared between the groups.

Results

The pregnancy outcomes between groups A and B showed a significant differences in the chemical (40.1% vs 27.4%; p = 0.010) and clinical pregnancies (32.8% vs 22.2%; p = 0.040), respectively. The rate of miscarriage tended to be higher and live birth rate tended to be lower in group B than in group A. Also, significantly higher rates were noted in chemical pregnancy, clinical pregnancy, and live birth in group A when compared with subgroup B2.

Conclusion

Higher rates of pregnancy and live birth were achieved in day-3 ET after three days of progesterone administration in FET cycles.

Steroid hormones and first trimester vascular remodeling

Successful implantation and placentation require neoangiogenesis and the remodeling of the uterine spiral arteries. Progesterone and estradiol control various of the placental functions, but their role in vascular remodeling remains controversial. Therefore, this chapter aims to summarize the current knowledge regarding the role of steroid hormones in the uteroplacental vascular remodeling during the first trimester of gestation.

The predictive value of serial serum estradiol and serial endometrial volume on endometrial receptivity on assisted reproductive technology cycles

Background

Diagnosis of endometrial receptivity is still unclear and conflicting. Despite advances in embryo development during assisted reproductive technologies (ART) cycles, the intricate process of implantation is still matter for debate and research.

Materials and methods

Prospective case control of 169 subjects during ovarian controlled stimulation for ART. Endometrial receptivity assessment to predict clinical pregnancy with serial continuous biochemical (serum estradiol) and biophysical (endometrial volume and adjusted endometrial volume) parameters were used. Both parameters were compared between negative and positive outcome in terms of clinical pregnancy.

Results

No statistical difference was noted between the two groups in terms of demographics and ART procedures and scores. Serum estradiol was significantly higher in the positive group from day 8 after ovarian controlled stimulation. Endometrial volume and adjusted endometrial volume were significantly higher in the positive group as soon as day 6 of ovarian controlled stimulation.

Conclusions

Continuous serum estradiol and 3D endometrial volume and adjusted endometrial volumes may reflect endometrial changes during ART procedures and provide a useful real time tool for clinicians in predicting endometrial receptivity.

Prospective analysis of progesterone exposure in programmed single thawed euploid embryo transfer cycles and outcomes

PURPOSE

In the era of personalized medicine and the increased use of frozen embryo transfer (FET), assay of the endometrium's receptivity prior to transfer has gained popularity, especially among patients. However, the optimal timing for single thawed euploid embryo transfers (STEET) in a programmed FET has yet to be determined Mackens et al. (Hum Reprod. 32(11):2234-42, 2017). We sought to examine the outcomes of euploid FETs by length of progesterone (P4) exposure.

METHODS

Prospective cohort study of programmed FETs of single euploid embryos between June 1, 2018, and December, 18, 2018, at our center. Subjects reported the exact start time for initiating progesterone. The transfer time was noted to calculate the primary independent variable, duration of progesterone exposure. Statistical analysis included ANOVA and Spearman's rho correlation, with p < 0.05 considered significant.

RESULTS

Inclusion criteria were met for 253 programmed STEET cycles in the analysis. There was no significant difference in P4 duration when comparing outcome groups (112.8 ± 3.1 ongoing pregnancy (OP), 112.4 ± 4.4 spontaneous abortion (SAB), 111.6 ± 1.7 biochemical pregnancy (BP), 113.9 ± 5.7 no pregnancy (NP), F 1.76, df 3, p = 0.16). An ROC curve assessing the ability of P4 duration to predict ongoing pregnancy (OP) had an area under the curve of 0.467 (p = 0.38).

CONCLUSION

Duration of P4 was not associated with outcome. Of the cycles, 65.6% resulted in ongoing pregnancy with our center's instructions resulting in an average progesterone exposure of 112.8 h, with a range of 98.3-123.7 h. With growing popularity for individualized testing, these results provide evidence for patient counseling of the high likelihood of ongoing pregnancy without personalized testing.

Effectiveness of electroacupuncture for thin endometrium in infertile women: study protocol for a single-blind, randomized controlled trial

BACKGROUND

Thin endometrium negatively impacts the reproductive function. Current treatments for thin endometrium do not always improve endometrial receptivity. Preliminary evidence suggests that electroacupuncture could have potential therapy for thin endometrium in infertile women. Thus, this randomized controlled trial was designed to test whether electroacupuncture can improve endometrial receptivity in infertile women with thin endometrium.

METHODS

This study is a randomized, single-blinded, controlled, clinical trial. A total of 142 eligible patients will be recruited and randomly assigned to the electroacupuncture (EA) group or the sham electroacupuncture (SEA) group in a 1:1 ratio. Participants will receive 36 sessions over three menstrual cycles (12 weeks in total), with the same acupoint prescription. The primary outcome of this trial is endometrial thickness in the midluteal phase. The secondary outcomes include endometrial pattern, resistance index (RI) and pulsatility index (PI) of bilateral uterine artery and endometrium blood flow, serum estradiol (E2) and progesterone (P), and pregnancy rate. The pregnancy rate will be evaluated during a 6-month follow-up after completion of the trial. All other outcomes will be evaluated before treatment, during the treatment of 1st, 2nd, and 3rd menstrual cycle, and 6 months after treatment.

DISCUSSION

If the outcome confirms the effectiveness of electroacupuncture for thin endometrium in infertile women, this treatment will be proposed for application in clinical practice.

TRIAL REGISTRATION

Chinese Clinical Trials Registry ChiCTR2 000029983. Registered on 18 February 2020.

Histomorphometric analysis of goat uterine tissue on in vitro exposure with ovarian hormones and mifepristone

Uterus, the largest reproductive tract organ in female mammals, is the site of implantation of fertilised egg and foetus development. Uterus is a dynamic reproductive organ; its morphology alters with reproductive phase and steroidal cues. The aim of the present study was to assess the effects of progesterone (P4), estrogen (E2) and antiprogestogen i.e., mifepristone on goat’s uterine histoarchitecture in in vitro short term culture. Uterine tissue slices were cultured in the presence of E2, P4 and mifepristone at the dose of 10–9 M, 10–7 M and 10–6 M respectively for 24 hours. Uter-ine morphology of E2- and P4-treated groups did not reveal marked changes from that of control group. Mifepristone treatment caused conspicuous changes in uterine histoarchitecture, led to congested endometrium, regressed uterine glands and constricted blood vessels. The changes ob-served in morphometry after E2 and P4 exposure included increased uterine gland diameter (47.00 and 45.95 µm respectively) and glandular epithelial cell height (18.37 and 17.43 µm respectively) while the mifepristone treatment resulted in significant reduction of gland diameter (34.95 µm) as well as epithelium height (14.25 µm) as compared to those in control group (39.9 and 15.56 µm respectively). These morphometrical changes revealed prominent regressive changes in anti-progestin treated group while E2 and P4 showed prolific effects in in vitro culture. Thus it is envis-aged that E2 and P4 induced characteristic progressive changes in the histologic structure especially in endometrial glands of the goat uterus while anti-steroidogenic formulation i.e. mifepristone severely reduced the normal histoarchitecture of the uterus which is a prerequisite for implanta-tion.

Effect of ovarian stimulation by different gonadotrophin treatments on in vivo and in vitro reproductive efficiency of rabbit does under high ambient temperature

Non-lactating multiparous NZW rabbit does (n = 227) were used in two experiments. In the 1st experiment (n = 87), does were i.m. injected with 0.1-ml saline/doe in day 0 (control, n = 29). Other does were injected with 25 IU equine chorionic gonadotrophin (eCG), followed by 0.2-ml gonadotrophin-releasing hormone (GnRH, n = 29) or 75 IU human chorionic gonadotrophin (hCG, n = 29) per doe 48 h later. After 60 h of day 0, does in all groups were artificially inseminated (AI). In the 2nd experiment, does (n = 140) were mated (AI) after synchronization of estrus/ovulation with 25 IU eCG, and 75 IU hCG 48 h later. On day 5 post-AI, does were injected with saline (control), 75 IU hCG, 0.2 ml GnRH, or 25 IU eCG per doe. Injection of eCG with GnRH or hCG pre-AI significantly increased corpora lutea number, ovulation rate, total number/doe and recovery rate of embryos, viable embryos, hatched blastocysts, in vivo reproductive parameters, and concentration of progesterone and progesterone/estradiol 17-β ratio. Injection of eCG on day 5 post-AI significantly improved large and total follicle number, and in vivo reproductive efficiency. The corpora lutea number and impantation sites were significantly increased in the hCG and eCG groups. Fetal loss rate significantly increased only in the GnRH group. Under high ambient temperature, administration of eCG with hCG or GnRH injection pre-AI could be synchronized estrus/ovulation for improving in vivo and in vitro embryo production. In addition, pregnancy outcomes could be enhanced in rabbit does induced to ovulation by a single eCG or hCG dose on day 5 post-AI.

A Novel Molecule in Human Cyclic Endometrium: LncRNA TUNAR Is Involved in Embryo Implantation

Embryo implantation rate remains an inefficient process in in vitro fertilization and embryo transfer (IVF-ET) cycles. The role long non-coding RNA (lncRNA) plays in embryo implantation remains unclear. We aimed to investigate the expression pattern of lncRNA TCL1 upstream neural differentiation-associated RNA (TUNAR) in human cyclic endometrium and clarify the role of TUNAR in the development of endometrial receptivity. Endometrial biopsies were collected at the late proliferative phase, luteinizing hormone (LH) + 2 and LH + 7, from patients with or without recurrent implantation failure (RIF). Real-time RT PCR was performed to detect the level of lncRNAs. After pZW1-snoVector-TUNAR transfection, multiple function of TUNAR in endometrial epithelial cells (EECs) and endometrial stromal cells (ESCs) was investigated. The expression of TUNAR in endometrium was found down-regulated at LH + 7 and up-regulated in RIF patients. In proliferative phase, TUNAR was overwhelmingly more abundant in ESCs and regulated its proliferation. In LH + 7, the difference in the expression of TUNAR between ESCs and EECs was narrowed. Overexpression of TUNAR not only impaired spheroid attachment to EECs, but also inhibited decidualization of ESCs. TUNAR was found expressed in human endometrium for the first time, which might be involved in embryo implantation by modulating the blastocyst attachment to the endometrial epithelium and regulating the proliferation and decidualization of ESCs. Our study helps us to better understand the molecular mechanisms of embryo implantation and may provide a promising biomarker of endometrial receptivity.

Ovarian stimulation and exogenous progesterone affect the endometrial miR-16-5p, VEGF protein expression, and angiogenesis

Angiogenesis, where vascular endothelial growth factor (VEGF) is critically involved, is an important factor in endometrial receptivity. Angio-miRNAs form a special class of microRNAs (miRNAs) that target angiogenic genes and regulate angiogenesis. Various studies have shown that ovarian stimulation and exogenous progesterone affect endometrial vascular density. The present research aimed to assess the impact of HMG/HCG and progesterone on miR-16-5p, VEGF protein expression, and angiogenesis in the mouse endometrium during the preimplantation period. Forty adult female mice were divided into four groups: 1) control, 2) ovarian stimulation (HMG and 48 h after HCG IP), 3) progesterone (progesterone IP for 3 days), 4) ovarian stimulation + progesterone (HMG and 48 h after HCG IP) + (progesterone IP for 3 days) groups.The mice were sacrificed 96 h following HCG administration. miR-16-5p, VEGF protein expression, and CD31-positive cell (Endothelial cell) density were specified.The results showed that endothelial cell density,VEGF protein, and miR-16-5p expression increased in all treatment groups, with the maximum increase belonging to the ovarian stimulation + progesterone group. This study provides evidence that ovarian stimulation and progesterone administration enhance endometrial angiogenesis through VEGF protein upregulation. Furthermore, except for miR-16-5p, other miRNAs and molecules appear to be involved in angiogenic pathways, thereby requiring further studies.

[Endometrial receptivity in assisted reproductive techniques: An aspect to investigate in embryo implantation failure]

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.

Effects of Testosterone on the Expression of Connexin 26 and Connexin 43 in the Uterus of Rats During Early Pregnancy

BACKGROUND/AIM

It was hypothesized that testosterone could affect the distribution and expression of connexin 26 and connexin 43 in the uterus. Thus, the effects of testosterone on these parameters in the uterus during the uterine receptivity period were investigated.

MATERIALS AND METHODS

Intact pregnant rats were administered 1 mg/kg/day testosterone alone or in combination with flutamide, finasteride or anastrozole, subcutaneously on day-1 of pregnancy till day 3. The rats were sacrificed at day 4 of pregnancy, which was considered as the uterine receptivity period for determining the expression and distribution of connexin 26 and connexion 43 by immunohistochemistry and quantitative polymerase chain reaction, respectively.

RESULTS

Treatment with 1 mg/kg/day testosterone increased connexin 26 and decreased connexin 43 mRNA expression and protein distribution in the uterus of early pregnancy rats.

CONCLUSION

Changes in the uterine connexin 26 and connexin 43 expression by testosterone could disrupt embryo implantation, resulting in early pregnancy loss.

Testosterone Decreases the Number of Implanting Embryos, Expression of Pinopode and L-selectin Ligand (MECA-79) in the Endometrium of Early Pregnant Rats

Testosterone could have adverse effect on fertility. In this study, we hypothesized that this hormone could reduce the number of embryo implantations via affecting the normal endometrium ultrastructure and expression of endometrial proteins involved in implantation. Therefore, the aims were to identify these adverse testosterone effects. Methods: Intact pregnant rats were given 250 or 500 µg/kg/day testosterone for three days, beginning from day 1 of pregnancy. Rats were euthanized either at day 4 to analyze the ultra-structural changes in the endometrium and expression and distribution of MECA-79 protein, or at day 6 to determine the number of implantation sites. Results: Administration of 500 µg/kg/day testosterone suppresses endometrial pinopodes development and down-regulates expression and distribution of MECA-79 protein in the uterus. In addition, the number of implantation sites were markedly decreased. Conclusions: Changes in endometrial ultrastructure and expression of implantation protein in the endometrium in early pregnancy period could be the reason for failure of embryo implantation under testosterone influence.

Levonorgestrel Inhibits Embryo Attachment by Eliminating Uterine Induction of Leukemia Inhibitory Factor

Progestogens including progesterone (P4) and levonorgestrel (LNG) are clinically used for multiple purposes such as contraception and infertility treatment. The effects of progestogens on the uterus remains to be elucidated. Here we examine the effect of excessive progestogen administration on embryo implantation focusing on the function of uterine leukemia inhibitory factor (LIF), a cytokine that is induced by estrogen and essential for embryo attachment. Treatment of wild-type (WT) female mice with vehicle (control), LNG at the dose of 300 μg/kg/day and P4 at the dose of 10 mg/day from day 1 to day 4 of pregnancy was conducted. LNG-treated and P4-treated mice showed embryo attachment failure on day 5 of pregnancy (The rate of mice with embryo attachment sites [%MAS], 11% and 13%, respectively), while all the control mice had normal attachment sites. Uterine LIF expression was significantly reduced in LNG-treated and P4-treated mice on day 4 evening. Administration of recombinant LIF (rLIF) at the dose of 24 μg/day on day 4 significantly rescued embryo attachment failure in LNG-treated and P4-treated mice (%MAS, 80% and 75%, respectively). Estradiol (E2) administration also rescued embryo attachment failure in LNG-treated mice (%MAS, 83%). Furthermore, excess P4 treatment before implantation decreased decidual P4 receptor (PGR) expression and induced decidualization defect apart from LIF downregulation. These findings indicate that progestogens cause embryo attachment inhibition through downregulation of uterine LIF expression and compromised decidualization through downregulation of PGR independently of LIF reduction. This study may contribute to a better understanding of contraceptive action of progestogens.

Does high estrogen level negatively affect pregnancy success in frozen embryo transfer?

Introduction

High estrogen levels could reduce pregnancy rates by disrupting the implantation of the embryo into the endometrium in patients treated with fresh cycles of in vitro fertilization. The aim of the present study was to investigate the effect of estrogen levels on the pregnancy and abortion rate in autologous frozen embryo transfer with hormone replacement therapy (HRT).

Material and methods

A historical cohort study was conducted in an academic setting to investigate the effect of estrogen levels on the pregnancy and abortion rates for all autologous artificial frozen embryo transfer cycles performed from January 2016 to January 2018. Serum estradiol levels recorded on day 2 or 3 of the cycle were stated as e1, and levels recorded on the day of progesterone were indicated as e2. Human chorionic gonadotropin (β-hCG) positivity, which was examined 14 days after the transfer, was used to evaluate biochemical pregnancy. Abortion was defined as the termination of pregnancy before the 20th gestational week.

Results

There were 130 patients with unexplained infertility, 20 patients with poor ovarian reserve, and 54 patients with male factor. Of the patients with unexplained infertility, poor ovarian reserve, and male factor, 58, 4, and 27 of them were pregnant, respectively. No statistically significant difference was found between the e1 and e2 levels of the pregnant and non-pregnant groups (p = 0.273, p = 0.219). In addition, there was no statistically significant difference between e2 levels in terms of the abortion rate (p = 0.722).

Conclusions

In autologous frozen embryo transfer with HRT, estrogen levels did not have a significant effect on the pregnancy or abortion rate. Therefore, estrogen levels do not need to be monitored in frozen embryo transfer with HRT.

Endometrial preparation for frozen-thawed embryo transfer in an artificial cycle: transdermal versus vaginal estrogen

The objective was to compare the endometrial thickness (ET) in a frozen embryo transfer (FET) cycle between transdermal and vaginal estrogen. Our secondary objectives were to compare the patient satisfaction and the pregnancy outcomes. Prospective monocentric cohort study between 01/2017 and 12/2017 at a single institution. Choice of administration was left to the patient. 119 cycles had transdermal estrogen (T-group) and 199 had vaginal estrogen (V-group). The ET at 10 ± 1 days of treatment was significantly higher in the T-group compared to the V-group (9.9 vs 9.3 mm, p = 0.03). In the T-group, the mean duration of treatment was shorter (13.6 vs 15.5 days, p < 0.001). The rate of cycle cancelation was comparable between the two groups (12.6% vs 8.5%, p = 0.24). Serum estradiol levels were significantly lower (268 vs 1332 pg/ml, p < 0.001), and serum LH levels were significantly higher (12.1 ± 16.5 vs 5 ± 7.5 mIU/ml, p < 0.001) in the T-group. Patient satisfaction was higher in the T-group (p = 0.04) and 85.7% (36/42) of women who had received both treatments preferred the transdermal over the vaginal route. Live birth rates were comparable between the two groups (18% vs 19%, p = 0.1). Transdermal estrogen in artificial FET cycles was associated with higher ET, shorter treatment duration and better tolerance.

The proteome of IVF-induced aberrant embryo-maternal crosstalk by implantation stage in ewes

Background

Implantation failure limits the success of in vitro fertilization and embryo transfer (IVF-ET). Well-organized embryo-maternal crosstalk is essential for successful implantation. Previous studies mainly focused on the aberrant development of in vitro fertilized (IVF) embryos. In contrast, the mechanism of IVF-induced aberrant embryo-maternal crosstalk is not well defined.

Results

In the present study, using ewes as the model, we profiled the proteome that features aberrant IVF embryo-maternal crosstalk following IVF-ET. By comparing in vivo (IVO) and IVF conceptuses, as well as matched endometrial caruncular (C) and intercaruncular (IC) areas, we filtered out 207, 295, and 403 differentially expressed proteins (DEPs) in each comparison. Proteome functional analysis showed that the IVF conceptuses were characterized by the increased abundance of energy metabolism and proliferation-related proteins, and the decreased abundance of methyl metabolism-related proteins. In addition, IVF endometrial C areas showed the decreased abundance of endometrial remodeling and redox homeostasis-related proteins; while IC areas displayed the aberrant abundance of protein homeostasis and extracellular matrix (ECM) interaction-related proteins. Based on these observations, we propose a model depicting the disrupted embryo-maternal crosstalk following IVF-ET: Aberrant energy metabolism and redox homeostasis of IVF embryos, might lead to an aberrant endometrial response to conceptus-derived pregnancy signals, thus impairing maternal receptivity. In turn, the suboptimal uterine environment might stimulate a compensation effect of the IVF conceptuses, which was revealed as enhanced energy metabolism and over-proliferation.

Conclusion

Systematic proteomic profiling provides insights to understand the mechanisms that underlie the aberrant IVF embryo-maternal crosstalk. This might be helpful to develop practical strategies to prevent implantation failure following IVF-ET.

Transcriptome sequencing of endometrium revealed alterations in mRNAs and lncRNAs after ovarian stimulation

RESEARCH QUESTION

Using RNA-sequencing analysis, we investigated the relationship between ovarian stimulation and endometrial transcriptome profiles during the window of implantation (WOI) to identify candidate predictive factors for the WOI and to optimize timing for embryo transfer.

METHODS

Twelve women with normal basal hormone levels and regular ovulation were randomly assigned into three groups based on sampling time: late-proliferate phase (P group), and receptive phase in natural cycles (LH+7, N group) and stimulated cycles (hCG+7, S group). Transcriptome profiles of mRNAs and long non-coding RNAs (lncRNAs) were then compared among the three groups. Validation was performed using real-time qPCR.

RESULTS

Comparison of transcriptome profiles between the natural and stimulated endometrium revealed 173 differentially expressed genes (DEGs), with a > 2-fold change (FC) and p < 0.05, under the influence of supraphysiological estradiol (E2) induced by ovarian stimulation. By clustering and KEGG pathway analysis, molecules and pathways associated with endometrial receptivity were identified. Of the 39 DEGs common to the three groups, eight genes were validated using real-time PCR. ESR1, MMP10, and HPSE were previously reported to be associated with endometrial receptivity. In addition, three novel genes (IL13RA2, ZCCHC12, SRARP) and two lncRNAs (LINC01060, LINC01104) were new potential endometrial receptivity-related markers.

CONCLUSION

Using mRNA and lncRNA sequencing, we found that supraphysiological E2 levels from ovarian stimulation had a marked impact upon endometrial transcriptome profiles and may result in a shift of the WOI. The precise mechanisms underlying the supraphysiological hormone-induced shift of the WOI require further research.

REGISTRATION NUMBER

ChiCTR180001453.

Impact of Serum Estradiol Levels Prior to Progesterone Administration in Artificially Prepared Frozen Embryo Transfer Cycles

Background: The need for endocrine monitoring in artificial cycles for frozen embryo transfer (FET) remains unclear and, more specifically, the value of the late-proliferative phase serum estradiol (E2) levels is with conflicting evidence in current literature. Objective: To investigate whether artificial FET cycles require endocrine monitoring for the serum E2 level prior to initiation of exogenous progesterone administration after an endometrial thickness of 6.5 mm has been reached. Design: One thousand two hundred and twenty-two (n = 1,222) artificial FETs performed in a tertiary center between 2010 and 2015 were subdivided into 3 groups according to the following late-proliferative serum E2 level percentiles: ≤p10 (E2 ≤144 pg/ml; n = 124), p11-p90 (E2 from 145 to 438 pg/ml; n = 977) and >p90 (E2 >439 pg/ml; n = 121). A mixed-effects multilevel multivariable regression analysis was performed to assess the potential effect of the late-proliferative E2 level on the live birth rate (LBR). Results: The level of late-proliferative circulating E2 showed no significant difference in terms of LBR after FET. Specifically, the multivariable regression model demonstrated a LBR of 19.5% for the p11-p90 reference group, compared to 24.4% for the ≤p10 (p = 0.251) and 19.5% for the >p90 group (p = 0.989). Conclusion: In this large retrospective dataset, no association was observed between late-proliferative phase serum E2 levels and LBR following FET in artificially prepared cycles. Although, caution is warranted due to the retrospective nature of the analysis and the potential for unmeasured confounding, we argue that monitoring of the late-proliferative serum E2 levels and using them to guide clinical decision-making (e.g., medication step-up, cycle prolongation or cancelation) may be of questionable value.

Molecular Signaling Regulating Endometrium-Blastocyst Crosstalk

Implantation of the embryo into the uterine endometrium is one of the most finely-regulated processes that leads to the establishment of a successful pregnancy. A plethora of factors are released in a time-specific fashion to synchronize the differentiation program of both the embryo and the endometrium. Indeed, blastocyst implantation in the uterus occurs in a limited time frame called the "window of implantation" (WOI), during which the maternal endometrium undergoes dramatic changes, collectively called "decidualization". Decidualization is guided not just by maternal factors (e.g., estrogen, progesterone, thyroid hormone), but also by molecules secreted by the embryo, such as chorionic gonadotropin (CG) and interleukin-1β (IL-1 β), just to cite few. Once reached the uterine cavity, the embryo orients correctly toward the uterine epithelium, interacts with specialized structures, called pinopodes, and begins the process of adhesion and invasion. All these events are guided by factors secreted by both the endometrium and the embryo, such as leukemia inhibitory factor (LIF), integrins and their ligands, adhesion molecules, Notch family members, and metalloproteinases and their inhibitors. The aim of this review is to give an overview of the factors and mechanisms regulating implantation, with a focus on those involved in the complex crosstalk between the blastocyst and the endometrium.

[Progesterone and frozen-thawed embryo transfer after hormonal replacement therapy for endometrial preparation: An update on medical practices]

Frozen-thawed embryo transfer (FET) has recently become the most frequently performed ART procedure. Many protocols for endometrial preparation are used, without any evidence-based superiority of one protocol above the others. Most French fertility centers mainly use hormonal replacement treatment (HRT) for endometrial preparation for organizational reasons. According to some studies, early pregnancy losses rate is higher with HRT endometrial preparation for FET than with other protocols, leading to new insights in improving outcomes into ART centers. There is a lack of consensual guidelines regarding the use of HRT for FET: there are various protocols, with different dosages, duration and routes for progesterone (PG) prescription. To date, the vaginal route is the most popular around the world as it gives higher intra-uterine concentration of PG because of the first uterine pass. However, recent scientific publications have pointed the importance of PG measurement in order to detect a lack of PG supplementation. Whatever the route of administration, it seems that a significant proportion of patients do not reach adequate PG concentrations for successful implantation and ongoing pregnancy. Timing of the measurement and ideal serum PG rate to reach are yet to be defined. What treatment strategy to adopt according to the results is still under investigation. Individualization of PG doses and routes of administration could lead to a decrease in miscarriages and better outcome.

Embryo transfer strategy and therapeutic options in infertile patients with thin endometrium: a systematic review

Human endometrium has a key role in implantation process. The measurement of endometrial thickness is the most commonly used in clinical practice. Managing patients with thin endometrium still represents a major challenge for clinicians. The objective of this systematic review was to investigate all available interventions to improve endometrial thickness (EMT) in women with history of thin endometrium undergoing fresh or frozen-thawed embryo transfers (ET). We performed a comprehensive search of relevant studies from January 1978 to February 2018. The different strategies were categorized as hormonal, vascular, and growth factor approaches and specifically analyzed according to the type of ET. Thirty-one studies were included. Overall, quality of the evidence ranged from very low to moderate, with only few randomized controlled trials that support the use of either GnRH analogues in fresh ET or sildenafil in frozen ET for enhancing endometrial growth. Besides, intensified estradiol administration is a common approach that might improve EMT in frozen ET. The present review evidences the paucity of reliable data regarding the efficiency of different interventions aiming at increasing EMT before fresh or frozen-thawed ET. Robust and high-quality randomized controlled trials are still needed before guidelines can be established.

Decreased NDRG1 expression is associated with pregnancy loss in mice and attenuates the in vitro decidualization of endometrial stromal cells

Embryo implantation is an essential step for a successful pregnancy, and any defect in this process can lead to a range of pregnancy pathologies. The objective of this study was to explore the role of N-myc downregulated gene 1 (NDRG1) in embryo implantation. It was found that uterine NDRG1 expression has a dynamic pattern during the estrous cycle in nonpregnant mice and that uterine NDRG1 expression was elevated during the implantation process in pregnant mice. The distinct accumulation of NDRG1 protein signals was observed in the primary decidual zone adjacent to the implanting embryo during early pregnancy. Furthermore, uterine NDRG1 expression could be induced by activated implantation or artificial decidualization in mice. Decreased uterine NDRG1 expression was associated with pregnancy loss in mice and was associated with recurrent miscarriages in humans. The in vitro decidualization of both mouse and human endometrial stromal cells (ESCs) was accompanied by increased NDRG1 expression and downregulated NDRG1 expression in ESCs effectively inhibited decidualization. Collectively, these data suggest that NDRG1 plays an important role in decidualization during the implantation process, and the abnormal expression of NDRG1 may be involved in pregnancy loss.

Pregnancy rates from natural and artificial cycles of women submitted to frozen embryo transfers: a metanalysis

Objective:

To compare pregnancy rates from natural and artificial cycles of women submitted to frozen embryo transfers.

Methods:

A systematic review was performed by PubMed search using the following algorithm: (endometrial [All Fields] AND preparation [All Fields]) AND (("freezing"[MeSH Terms] OR "freezing"[All Fields] OR "frozen"[All Fields]) AND thawed [All Fields]) and (natural cycles) AND (artificial cycle). Inclusion criteria: prospective and retrospective cohort studies. Exclusion criteria: use of hCG in the natural cycle, oocyte donors, and use of disused freezing techniques. Data were analyzed with the SPSS v.23 software and with a significance level of 5%. The meta-analysis was performed with RevMan 5.3 software. I² was calculated.

Results:

709 papers were retrieved. Five studies fulfilled the inclusion and exclusion criteria. From these studies, we analyzed 8,968 natural or artificial cycles. A contingency table compared the results of the natural and artificial cycles and the number of clinical pregnancies obtained in each selected paper. The I² test resulted in high statistical heterogeneity (I²=77%). Studies by Morozov et al. (2007) and Zheng et al. (2015) obtained statistically significant results (p<0.03 and p<0.001): Morozov et al. (2007) found a higher pregnancy rate within natural cycles, and Zheng et al. (2015) found more positive outcomes when analyzing artificial cycles. The remaining selected studies did not show any statistical significance.

Conclusion

There is insufficient scientific evidence to state that the artificial cycle yields better pregnancy rates than the natural cycle in women submitted to frozen embryo transfer. Limitations of this study include a small number of papers and heterogeneity among the studies.

Effects of hormone replacement therapy on endometrial hormone concentrations and progesterone receptor expression in recurrent pregnancy loss: a self-controlled study

AIM

To investigate the differential effects of endometrial preparation approaches, natural cycle (NC) and hormone replacement therapy (HRT), on the endometrial hormone conditions in patients with recurrent pregnancy loss (RPL).

METHODS

42 RPL patients were recruited, and a self-controlled trial was conducted to compare the effectiveness of NC to HRT on the same patient. The estradiol (E2) and progesterone (P) levels in both serum and endometrial tissue were measured in NC and HRT, respectively. Meanwhile, the expression levels of endometrial progesterone receptor A (PRA) and progesterone receptor B (PRB) were also compared between NC and HRT cycles during the window of receptivity. All statistical analyses were performed using GraphPad Prism 5, and data were averaged across subjects and tested for significance by pair-samples t-test.

RESULTS

Hormone replacement slightly decreased serum E2 and P levels (0.9- and 0.8-fold in average, respectively), significantly elevated endometrial E2 and P (2.1- and 14.5-fold in average, respectively), and reduced endometrial E2/P ratio (0.34-fold in average) compared to the NC condition. However, no correlation was found between serum and endometrial hormone concentrations. Further, the PRA/PRB ratios of both stromal and glandular cells were comparable between HRT and NC conditions, even though stromal PRA expression was slightly elevated by HRT compared to NC (1.63±0.96 vs 1.18±0.99, p =.0173).

CONCLUSION

The effects of HRT for endometrial preparation are similar or slightly superior to NC in RPL patients.

Bisphenol A affects estradiol metabolism by targeting CYP1A1 and CYP19A1 in human placental JEG-3 cells

Estradiol, in some way or another, plays a critically important physiologic role in the establishment and maintenance of pregnancy. This study was designed to investigate whether BPA affects the estradiol level of human placental JEG-3 cells, which may contribute to insights into the reproductive toxicity and endocrine disruption of BPA. The JEG-3 cells were treated with increasing concentrations of BPA (0.1 to 50 μM). We observed that BPA significantly reduced estradiol level of JEG-3 cells in a dose-dependent manner, which was accompanied by an increase in CYP1A1 protein level and an inhibition of CYP19A1 protein level. Additionally, by lentiviral transduction, we determined that estradiol level of JEG-3 cells over-expressing CYP1A1 gene was notably decreased and the decrease was of 84.9% compared to the control. Meanwhile, estradiol was almost undetectable in CYP19A1 knockdown group. On the contrary, the group with over-expression of CYP19A1 gene increased estradiol level by 8.6 fold while the CYP1A1 knockdown group increased by 5.6 fold. In summary, our research clearly showed that BPA alters JEG-3 estradiol synthesis and catabolism due to its action on CYP1A1 and CYP19A1 protein levels and may interfere with the normal process of placenta formation and embryonic development during early pregnancy.