Controlled ovarian stimulation induces a functional genomic delay of the endometrium with potential clinical implications

Premature formation of nucleolar channel systems indicates advanced endometrial maturation following controlled ovarian hyperstimulation

STUDY QUESTION

Is there a shift in the timing of nucleolar channel system (NCS) formation following controlled ovarian hyperstimulation (COH)?

SUMMARY ANSWER

NCSs appear prematurely following COH compared with natural cycles.

WHAT IS KNOWN ALREADY

During natural cycles, NCSs of endometrial epithelial cell (EEC) nuclei are exclusively present during the window of implantation and are uniformly distributed throughout the upper endometrial cavity.

STUDY DESIGN, SIZE, DURATION

Prospective two-cohort study. Cohorts I and II each consisted of seven volunteers for the duration of three menstrual study cycles that were separated by at least one wash-out or rest cycle, between December 2008 and May 2012.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants were recruited from a pool of healthy oocyte donors. Consecutive endometrial biopsies were obtained during the same luteal phase on cycle days (CD) 16, 20 and 26 for Cohort I, and on CD14, 22 and 24 for Cohort II, following random assignment to a natural cycle group, a COH cycle group (using a GnRH antagonist), or a COH cycle group receiving luteal phase hormonal supplementation (COH + S). The day of oocyte retrieval was designated CD14 in COH cycles and the day of the LH surge was designated CD13 in natural cycles. Prevalence of NCSs in the nuclei of EECs was quantified using indirect immunofluorescence with an antibody directed against a subset of related nuclear pore complex proteins that are major constituents of NCSs. Progesterone and estradiol levels were measured on the day of each endometrial biopsy.

MAIN RESULTS AND THE ROLE OF CHANCE

The natural cycle group exhibited peak NCS prevalence on CD20 [53.3%; interquartile range (IQR) 28.5-55.8], which rapidly declined on CD22 (11.8%; IQR 6.3-17.6), CD24 (2.5%; IQR 0.0-9.2) and CD26 (0.3%; IQR 0.0-3.5), and no NCSs on CD14 and 16 defining a short NCS window around CD20. In contrast, in COH and COH + S cycles, NCS prevalence was high already on CD16 (40.4%; IQR 22.6-53.4 and 35.6%; IQR 26.4-44.5, respectively; P = 0.001 compared with CD16 of the natural cycle group, Mann-Whitney), whereas no significant difference in NCS prevalence was detected on any of the other five CDs between the three groups (P > 0.05).

LIMITATIONS, REASONS FOR CAUTION

The cohort size was small (n = 7) but was offset by the all-or-none presence of NCSs on CD16 in natural versus COH and COH + S cycles and the fact that each subject served as her own control.

WIDER IMPLICATIONS OF THE FINDINGS

Premature appearance of NCSs and hence maturation of the endometrium following COH is consistent with previous studies based on histological dating but contradicts studies based on mRNA expression profiling, which reported a lag in endometrial maturation. However, this is the first study of this kind that is based on consecutive endometrial biopsies within the same cycle and that reports such clear-cut differences: no versus robust NCS presence on CD16. Our observation of advanced endometrial maturation following COH may contribute to the reduced implantation rates seen in fresh compared with frozen and donor IVF-embryo transfer cycles. Therefore, the NCS window could serve as a sensitive guide for timing of embryo transfer in frozen and donor cycles.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by the March of Dimes Birth Defects foundation (1-FY09-363 to U.T.M.); Ferring Pharmaceuticals, Parsippany, NJ; East Coast Fertility, Plainview, NY and the CMBG Training Program (T32 GM007491 to M.J.S.). We report no competing interests.

The science of implantation emerges blinking into the light

Although embryo implantation is essential for human survival, it remains an enigmatic biological phenomenon. Following fertilization, the resulting blastocyst must signal its presence to the mother, attach to the luminal epithelium of the endometrium and embed into the decidualising stroma. Failure to do so results in infertility, which affects around 9% of women. Subsequent placental development requires remodelling of maternal blood vessels by trophoblast cells from the placenta, that invade deep into the decidua. Failure in these very early stages can compromise fetal development, resulting in diseases of pregnancy such as intrauterine growth restriction or pre-eclampsia which can also impact on health in adulthood. Abnormal implantation therefore constitutes a significant disease burden in humans. Although we have known for many years that successful implantation requires an embryo that is competent to implant and an endometrium that is receptive, the molecular basis of these processes remains poorly understood. Our inability to identify implantation-competent embryos or to diagnose/treat the non-receptive endometrium therefore limits our ability to intervene through assisted reproduction techniques. This Implantation Symposium aims to review recent exciting developments in our understanding of the biology of early implantation and to highlight the rapid progress being made to translate these into improved diagnosis and treatment.

Tumor necrosis factor-308 polymorphism increases the embryo implantation rate in women undergoing in vitro fertilization

STUDY QUESTION

Do TNF-308 and -238 polymorphisms impact the embryo implantation rate after in vitro fertilization (IVF) in women without female infertility factor?

SUMMARY ANSWER

The presence of the TNF-308A allele is associated with high implantation and multiple pregnancy rates in women without known infertility factors after ovarian hyperstimulation with exogenous FSH.

WHAT IS ALREADY KNOWN

Multiple pregnancies are frequent after the use of Assisted Reproductive Technologies. Single embryo transfer (SET) has been proposed as a simple way to prevent these risks. However, the extension of SET indications to patients not selected based on specific criteria is controversial because of reduced pregnancy rates. To date, the predictive value of the parameters used for SET (age, gynecological history of the patient and uterine characteristics) allows a pregnancy rate of ~30%.

STUDY DESIGN, SIZE, DURATION

The potential predictive value of TNF polymorphisms (-308, rs1800629 and -238, rs361525) on implantation rate was evaluated in 424 women requiring IVF due to male fertility factors. This cohort retrospective study was conducted over 4 years in University-affiliated hospitals.

PARTICIPANTS, SETTING, METHODS

The entire patient group included 424 women undergoing intracytoplasmic sperm injection (ICSI) due to male fertility factors without the contribution of any female factor. From among this group, a selected patient group included 120 women with a normal karyotype, age under 38 years, serum follicle-stimulating hormone (Day-3 FSH) levels below 10 IU/l, a long agonist desensitization protocol associated with recombinant FSH treatment and a Caucasian background.

MAIN RESULTS AND THE ROLE OF CHANCE

The TNF-238 polymorphism was not associated with implantation rate. In contrast, the presence of the TNF-308A allele was associated with increased Day 3-E2 levels as well as higher implantation and multiple pregnancy rates after fresh embryo transfer in women from the entire and selected patient groups. Moreover, in the selected patient group, the presence of the TNF-308A allele was also associated with a decrease in the miscarriage rate. The benefit of the TNF-308A allele in predicting implantation rates was not observed after the use of frozen embryos.

LIMITATIONS, REASONS FOR CAUTION

Future studies are needed to evaluate whether the TNF-308A allele might also be a biomarker in women with infertility factors.

WIDER IMPLICATIONS OF THE FINDING

The TNF-308A allele may represent a good candidate for a potential predictive, non-invasive biomarker in the SET strategy. However, its impact should be evaluated in prospective studies.

STUDY FUNDING/COMPETING INTEREST

This study was conducted with financial support from the French Institute for Health and Medical Research (INSERM), Organon France for a FARO (Fond d'Aide à la Recherche Organon) fellowship (to V.T.) and CHU Nice PHRC (PHRC 09-279).There are no competing interests.

Endometrial signaling pathways during ovarian stimulation for assisted reproduction technology

OBJECTIVE

To determine the effects of different hormonal levels on endometrial biochemical development during ovulation induction for assisted reproduction technology (ART) cycles.

DESIGN

Prospective controlled study.

SETTING

University center.

PATIENT(S)

Nine women during a natural cycle (control) and 9 oocyte donors (treated) during an ART cycle.

INTERVENTION(S)

At the time consistent with day 3 embryo transfer (LH+5 in control, hCG+5 in treated), transvaginal ultrasound, endometrial biopsy, and blood sampling were performed. Real-time reverse-transcription polymerase chain reaction was used to measure mRNA levels for insulin receptor (InsR), type I IGF receptor (IGFRI), prolactin receptor (PRL-R), androgen receptor (AR), TSH receptor (TSHR), nuclear receptors for T3 and T4 (TRα1, TRα2, and TRβ1), iodothyronine deiodinase (DIO2), and 1,25-dihydroxyvitamin D3 receptor (VDR) in the endometrial tissue.

MAIN OUTCOME MEASURE(S)

Biochemical endometrial development.

RESULT(S)

IGFRI mRNA levels were 69% lower in treated patients than in control subjects, 0.12 ± 0.005 pg/μg RNA versus 0.39 ± 0.01 pg/μg RNA. TSHR mRNA was 57% lower, 2.6 ± 0.1 fg/μg RNA versus 6.0 ± 0.2 fg/μg RNA. TRα1 and TRα2 mRNA did not change, but TRβ1 mRNA levels were 63% higher. DIO2 mRNA was 63% lower, 1.2 ± 0.07 pg/μg RNA versus 3.2 ± 0.2 pg/μg RNA. InsR mRNA levels, despite being 68% lower in treated patients, did not reach significance, and PRL-R, AR, and VDR did not significantly change.

CONCLUSION(S)

Exposure of the endometrium to ovarian stimulation appears to influence insulin and thyroid hormone signaling pathways in the decidua at day 3 embryo transfer, whereas prolactin, androgen, and vitamin D pathways are uninfluenced. These findings echo the known delayed endometrial maturation during ovarian stimulation.

Low birth weight: is it related to assisted reproductive technology or underlying infertility?

Since 1978, we have witnessed a successful evolution of assisted reproductive technology (ART), with improvement of the pregnancy rates and a growing demand. However, in recent years, there has been increasing concern regarding its safety due to the potential health impact on its infants. The raise of the developmental origins of adult disease has positioned low birth weight (LBW) as a significant health issue. Although multiple studies have associated ART with LBW, the etiology of this association remains largely unknown. We review the potential association between different components of ART and infertility with LBW, while acknowledging the limitations of interpretation of the existing literature.

Biomarkers in reproductive medicine: the promise, and can it be fulfilled?

A biomarker can be used for early diagnosis of a disease, identification of individuals for disease prevention, as a potential drug target, or as a potential marker for a drug response. A biomarker may also limit the use of drug (and therefore costs) to the population of patients for which the drug will be safe and efficacious. A biomarker in reproduction could be used to improve assessment of exposure, identify subgroups susceptible to treatment, predict outcome, and/or differentiate subgroups with potentially different etiologies of disease. Despite many potential uses there is low participation in reproductive biology to develop molecular biomarkers, which may be directly related to the low number of new molecular entities entering clinical trials. As the number of candidate markers in reproductive medicine is increasing, it is important to understand the pathway of development from discovery to clinical utility and recognize that the vast majority of potential markers will not be clinically useful, owing to a variety of pitfalls. Extensive testing, validation, and modification needs to be performed before a biomarker is demonstrated to have clinical utility. New opportunities and partnerships exist and should hasten the development of biomarkers in reproduction. As more biomarkers are moved into practice, a better-educated biomarker consumer will enhance the possibility that biomarker(s) will realize their great potential.

Defective soil for a fertile seed? Altered endometrial development is detrimental to pregnancy success

Background

Synchronous development of the endometrium (to achieve a receptive state) and of the embryo is essential for successful implantation and ongoing pregnancy. Endometrial receptivity exists only for a finite time in a menstrual cycle and the endometrium is refractory to embryo implantation outside of this window. Administration of hormones to stimulate multifollicular development within the ovary, integral to the majority of assisted reproduction (ART) protocols, dramatically alters the hormonal milieu to which the endometrium is exposed versus normal menstrual cycles. Endometrial maturation may be profoundly affected by this altered endocrine environment.

Aim

Compare endometrial histology in fertile women, fertile women undergoing hormonal stimulation for oocyte donation and infertile women undergoing fresh embryo transfers in an ART cycle with further comparisons between women who did or did not become pregnant. Examine the presence of leukocytes and markers of endometrial maturation.

Methods

Endometrial histology was examined by hematoxylin and eosin staining with a semi quantitative scoring method developed to compare histological appearance of tissues. The presence of leukocytes and developmental markers was examined by immunohistochemistry and scored.

Results

Endometrial histology was dramatically altered upon stimulation for ART. However, those women who became pregnant presented with significantly less alterations in histological endometrial maturation. Numbers and activation status of leukocyte populations were also altered within the endometria stimulated for ART, with neutrophils undergoing degranulation, usually observed only pre-menstrually.

Conclusion

We propose that such developmental changes render the endometrium hostile to the embryo and that modifications to ART protocols should be considered to take account of the requirement for endometrial receptivity and hence increase pregnancy rates.

Endometrial response of beef heifers on day 7 following insemination to supraphysiological concentrations of progesterone associated with superovulation

Ovarian stimulation is a routine procedure in assisted reproduction to stimulate the growth of multiple follicles in naturally single-ovulating species including cattle and humans. The aim of this study was to analyze the changes induced in the endometrial transcriptome associated with superovulation in cattle and place these observations in the context of our previous data on changes in the endometrial transcriptome associated with elevated progesterone (P4) concentrations within the physiological range and those changes induced in the embryo due to superovulation. Mean serum P4 concentrations were significantly higher from day 4 to day 7 in superovulated compared with unstimulated control heifers (P < 0.05). Between-group analysis revealed a clear separation in the overall transcriptional profile of endometria from unstimulated control heifers (n = 5) compared with superovulated heifers (n = 5). This was reflected in the number of differentially expressed genes (DEGs) identified between the two groups with 795 up- and 440 downregulated in superovulated endometria. Ten times more genes were altered by superovulation (n = 1,234) compared with the number altered due to elevated P4 within physiological ranges by insertion of a P4-releasing intravaginal device (n = 124) with only 22 DEGs common to both models of P4 manipulation. Fewer genes were affected by superovulation in the embryo compared with the endometrium, (443 vs. 1,234 DEGs, respectively), and the manner in which genes were altered was different with 64.5% of genes up- and 35.5% of genes downregulated in the endometrium, compared with the 98.9% of DEGs upregulated in the embryo. In conclusion, superovulation induces significant changes in the transcriptome of the endometrium which are distinct from those in the embryo.

The extrapituitary effects of GnRH antagonists and their potential clinical implications: a narrated review

Potential roles of gonadotropin-releasing hormone (GnRH) antagonists on GnRH/GnRH receptor systems and their effects on the extrapituitary tissues are largely elusive. In this narrated review, we summarized the systemic effects of GnRH antagonists on ovary, endometrium, embryo implantation, placental development, fetal teratogenicity, reproductive tissue cancer cells, and heart while briefly reviewing the GnRH and GnRH receptor system. GnRH antagonists may have direct effects on ovarian granulosa cells. Data are conflicting regarding their effects on endometrial receptivity. The GnRH antagonists may potentially have detrimental effect on early placentation by decreasing the invasive ability of cytotrophoblasts if the exposure to them occurs during early pregnancy. The GnRH antagonists were not found to increase the rates of congenital malformations. Comparative clinical data are required to explore their systemic effects on various extrapituitary tissues such as on cardiac function in the long term as well as their potential use in other human cancers that express GnRH receptors.

Endometrial expression of selected genes in patients achieving pregnancy spontaneously or after ICSI and patients failing at least two ICSI cycles

The objective of this study was to identify the endometrial gene expression profile in receptive phase, which could represent a useful prognostic tool for selecting IVF patients. Endometrial expression of 47 selected genes biopsied during the window of implantation in natural cycles was compared between patients who achieved a successful pregnancy spontaneously or after subsequent intracytoplasmic sperm injection (ICSI) cycles and patients who did not achieve a pregnancy after at least two failed ICSI cycles. The comparative analysis showed significantly different levels of expression in 19 genes, five implicated in apoptosis (CASP8, FADD, CASP10, APAF1, ANXA4), three in immunity (LIF, SPP1, C4BPA), five in transcriptional activity (MSX1, HOXA10, MSX2, HOXA11, GATA2), two in lipid metabolism (LEPR, APOD) and four in oxidative metabolism (AOX1, ALDH1A3, GPX3, NNMT). The evidence for these genes being differently expressed could represent the starting point of identifying the ideal receptive endometrial gene expression profile, which could be used in the future as a prognostic tool for IVF patients. Gene expression analysis technology has opened new important perspectives on the study of the physiological processes of different tissues and organs. Specifically for the endometrium, it would be really interesting to find out an endometrial gene expression profile of receptive phase, which could be used in future as a useful prognostic tool for selecting IVF patients. To achieve this aim, the objective of the present paper was the comparison of endometrial expression in natural cycles of 47 selected genes between the biopsies of patients who achieved a successful pregnancy, either spontaneously or after subsequent ICSI cycles, and those of patients who did not achieve a pregnancy after at least two failed ICSI cycles. The comparative analysis showed a significant different expression in 19 genes: five implicated in programmed cell death, known as apoptosis (CASP8, FADD, CASP10, APAF1, ANXA4), three in immunity (LIF, SPP1, C4BPA), five in transcriptional activity (MSX1, HOXA10, MSX2, HOXA11, GATA2), two in lipid metabolism (LEPR, APOD) and four in oxidative metabolism (AOX1, ALDH1A3, GPX3, NNMT). The evidence of these genes being differently expressed could represent the starting point of identifying the ideal receptive endometrial gene expression profile which could be used in the future as a prognostic tool for IVF patients.

Gene expression confirms a potentially receptive endometrium identified by histology in fertile women

BACKGROUND

To use contemporary biochemical markers to characterize mRNA/gene expression in the potentially fertile secretory endometrium to confirm its identification based on histological characteristics in order to develop a clinically applicable test.

METHODS

Nine, fertile, cycling Caucasian women were sampled from one IVF clinic. Endometrial samples were collected from them in two to four menstrual cycles at 2 and 7 days post first significant rise in blood LH. Separate endometrial glands and stroma populations were obtained by laser microdissection. Linear polymerase chain reaction amplified mRNAs which were hybridized to both Affymetrix U133 Plus2 and Agilent 4 × 44K microarrays followed by gene set analysis. Four histopathologists reviewed the sample set using the same histological criteria to date and characterize the non-receptive and potentially receptive samples.

RESULTS

mRNA expression of microdissected glands and stroma provided molecular signatures that characterized the two specific phases of the cycle with distinct clustering patterns. Cell proliferation and five other associated biological pathways were significantly down-regulated when the endometrium is considered potentially receptive accompanied by an increase in secreted glycoproteins mRNAs in the potentially receptive glands. Reported histological findings identified the presence of one histological feature characteristic of each phase: glandular mitoses indicated a non-receptive endometrium, whereas a potentially receptive endometrium was distinguished by supranuclear vacuolation.

CONCLUSIONS

This study defined a transcriptome characteristic of active cell proliferation in the non-receptive samples with a marked overall down-regulation of this pathway in potentially receptive samples-suggesting a transitional state associated with receptivity but not implantation. However, microarrays involve expensive, specialized testing and require significant post-data analysis. Sampling according to endocrinological and molecular prediction improved the consistency of histological assessment and allowed reliable histological markers of glandular mitosis in the non-receptive phase and supranuclear vacuolation of the potentially receptive endometrium to be identified. Thus, histology can provide an affordable, clinically applicable test in the context of reproduction.

Molecular aspects of implantation failure

Despite expanding global experience with advanced reproductive technologies, the majority of IVF attempts do not result in a successful pregnancy, foremost as a result of implantation failure. The process of embryo implantation, a remarkably dynamic and precisely controlled molecular and cellular event, appears inefficient in humans and is poorly understood. However, insights gained from clinical implantation failure, early pregnancy loss, and emerging techologies that enable molecular interrogation of endometrial-embryo interactions are unravelling this major limiting step in human reproduction. We review current molecular concepts thought to underlie implantation failure, consider the contribution of embryonic and endometrial factors, and discuss the clinical value of putative markers of impaired endometrial receptivity. Finally we highlight the nature of the dialogue between the maternal endometrium and the implanting embryo and discuss the concept of natural embryo selection. This article is part of a Special Issue entitled: Molecular Genetics of Human Reproductive Failure.

Annexin A2 is critical for embryo adhesiveness to the human endometrium by RhoA activation through F-actin regulation

Annexin A2 (ANXA2) is present in vivo in the mid- and late-secretory endometria and is mainly localized in the luminal epithelium. Our aim was to evaluate its function in regulating the human implantation process. With an in vitro adhesion model, constructed to evaluate how the mouse embryo and JEG-3 spheroids attach to human endometrial epithelial cells, we demonstrated that ANXA2 inhibition significantly diminishes embryo adhesiveness. ANXA2 is also implicated in endometrial epithelial cell migration and trophoblast outgrowth. ANXA2 was seen to be linked to the RhoA/ROCK pathway and to regulate cell adhesion. We noted that ANXA2 inhibition significantly reduces active RhoA, although RhoA inactivation does not alter the ANXA2 levels. RhoA inactivation and ROCK inhibition also moderate embryo adhesiveness to endometrial epithelial cells. We corroborated that the induction of constitutively active RhoA partially reverses the effects of ANXA2 inhibition on endometrial adhesiveness. These molecules colocalize on the plasma membrane of endometrial epithelial cells, and a large proportion of ANXA2 and RhoA are colocalized in the F-actin networks. The functional effects of ANXA2 inhibition and RhoA/ROCK inactivation are associated with significant alterations in F-actin organization and its depolymerization. ANXA2 may act upstream of the RhoA/ROCK pathway by regulating F-actin remodeling and is a key factor in human endometrial adhesiveness.

The genomics of the human endometrium

The endometrium is a complex tissue that lines the inside of the endometrial cavity. The gene expression of the different endometrial cell types is regulated by ovarian steroids and paracrine-secreted molecules from neighbouring cells. Due to this regulation, the endometrium goes through cyclic modifications which can be divided simply into the proliferative phase, the secretory phase and the menstrual phase. Successful embryo implantation depends on three factors: embryo quality, the endometrium's state of receptivity, and a synchronised dialogue between the maternal tissue and the blastocyst. There is a need to characterise the endometrium's state of receptivity in order to prevent reproductive failure. No single molecular or histological marker for this status has yet been found. Here, we review the global transcriptomic analyses performed in the last decade on a normal human endometrium. These studies provide us with a clue about what global gene expression can be expected for a non-pathological endometrium. These studies have shown endometrial phase-specific transcriptomic profiles and common temporal gene expression patterns. We summarise the biological processes and genes regulated in the different phases of natural cycles and present other works on different conditions as well as a receptivity diagnostic tool based on a specific gene set profile. This article is part of a Special Issue entitled: Molecular Genetics of Human Reproductive Failure.

The duration of pre-ovulatory serum progesterone elevation before hCG administration affects the outcome of IVF/ICSI cycles

STUDY QUESTION

During controlled ovarian stimulation (COS), does the duration of premature serum progesterone (P) elevation before administration of hCG affect the outcomes of IVF/ICSI embryo transfer (-ET) cycles?

SUMMARY ANSWER

The duration of the premature serum P elevation is inversely related to the clinical pregnancy rate of IVF/ICSI-ET cycles.

WHAT IS KNOWN AND WHAT THIS PAPER ADDS

The majority of the previous studies only considered a single serum P measurement made on the day of hCG administration and the results of attempts to relate this to IVF/ICSI-ET outcomes were controversial. However, the effect of the duration of premature serum P elevation before the hCG administration on the outcomes of IVF/ICSI-ET cycles has not been studied well. Here we demonstrate that the duration of premature serum P elevation has a more significant inverse correlation than the absolute serum P concentration on the day of hCG administration with IVF/ICSI-ET outcomes.

DESIGN

It is a retrospective, single-centre cohort study. A total of 1784 IVF and/or ICSI-ET cycles were included from October 2005 to June 2011.

PARTICIPANTS AND SETTING

A total of 1784 patients underwent their IVF and/or ICSI-ET cycles in a university hospital IVF unit. The inclusion criteria include (i) age between 20 and 42 years and (ii) eligible indications for COS before IVF/ICSI.

MAIN RESULTS AND THE ROLE OF CHANCE

The duration of premature serum P elevation to >1 ng/ml is significantly inversely associated with the probability of clinical pregnancy (odds ratio = 0.773, 95% confidence interval: 0.660-0.891, P < 0.001), after adjustment for possible confounders with multivariate logistic regression analysis. However, the significance of inverse correlation between the absolute serum P concentration on the day of hCG administration with clinical pregnancy rate decreased after adjustment.

BIAS, CONFOUNDING AND OTHER REASONS FOR CAUTION

The cutoff value we chose to define premature serum P elevation (P > 1.0 ng/ml) might not be able to be applied to different immunoassay kits and study population. The retrospective nature of this study inevitably might be influenced by some selection bias.

GENERALIZABILITY TO OTHER POPULATIONS

Older patients (>42 years) are excluded from our study.

A short narrative review of the feasibility of adopting mild ovarian stimulation for IVF as the current standard of care

INTRODUCTION

Mild ovarian stimulation has been conceived, proposed and implemented in clinical practice as a safer and cheaper alternative to conventional strategies of controlled ovarian hyperstimulation in preparation for in vitro fertilization (IVF). Our aim was to summarize the key evidence on this topic and explore its possible role as the standard treatment option for women undergoing IVF.

MATERIALS AND METHODS

A short narrative review of the existing literature, with emphasis on mild ovarian stimulation clinical and cost effectiveness, as well as treatment limitations.

RESULTS

Numerous studies highlight mild ovarian stimulation's favorable characteristics with respect to oocyte/embryo quality, reduced patient risk, and ease of intervention. There is, however, a need for high-quality laboratory environment. Limitations regarding poor responders, older women, or those seeking ovarian stimulation for non-infertility indications should also be considered. Finally, outcomes on the cumulative success rates and the cost effectiveness of mild ovarian stimulation remain inconclusive.

CONCLUSION

Mild ovarian stimulation protocols for IVF should currently be implemented only in carefully selected populations. Further research is needed to clarify the remaining controversies in this IVF approach.

Research resource: interactome of human embryo implantation: identification of gene expression pathways, regulation, and integrated regulatory networks

A prerequisite for successful embryo implantation is adequate preparation of receptive endometrium and the establishment and maintenance of a viable embryo. The success of implantation further relies upon a two-way dialogue between the embryo and uterus. However, molecular bases of these preimplantation and implantation processes in humans are not well known. We performed genome expression analyses of human embryos (n = 128) and human endometria (n = 8). We integrated these data with protein-protein interactions in order to identify molecular networks within the endometrium and the embryo, and potential embryo-endometrium interactions at the time of implantation. For that, we applied a novel network profiling algorithm HyperModules, which combines topological module identification and functional enrichment analysis. We found a major wave of transcriptional down-regulation in preimplantation embryos. In receptive-stage endometrium, several genes and signaling pathways were identified, including JAK-STAT signaling and inflammatory pathways. The main curated embryo-endometrium interaction network highlighted the importance of cell adhesion molecules in the implantation process. We also identified cytokine-cytokine receptor interactions involved in implantation, where osteopontin (SPP1), leukemia inhibitory factor (LIF) and leptin (LEP) pathways were intertwining. Further, we identified a number of novel players in human embryo-endometrium interactions, such as apolipoprotein D (APOD), endothelin 1 (END1), fibroblast growth factor 7 (FGF7), gastrin (GAST), kringle containing trnasmembrane protein 1 (KREMEN1), neuropilin 1 (NRP1), serpin peptidase inhibitor clade A member 3 (SERPINA3), versican (VCAN), and others. Our findings provide a fundamental resource for better understanding of the genetic network that leads to successful embryo implantation. We demonstrate the first systems biology approach into the complex molecular network of the implantation process in humans.

A novel model of human implantation: 3D endometrium-like culture system to study attachment of human trophoblast (Jar) cell spheroids

There is an urgent need to develop optimized experimental models to examine human implantation. These studies aimed to (i) establish a human endometrium-like three-dimensional (3D) culture system, and (ii) examine the attachment of trophoblast-like Jar spheroids to the culture. In the present work, 3D endometrial cultures were constructed with fibrin-agarose as matrix scaffold, and using epithelial and stromal cells from both human primary cultures and established cell lines. An attachment assay between trophoblast cells and the 3D culture was developed. Epithelial cells (cytokeratin(+)) concentrated on top of the matrix forming a monolayer, and stromal cells (vimentin(+)) resided within the matrix, resembling the normal endometrial structure. The capability of primary epithelial cells to form glands spontaneously was observed. Human trophoblast cells (Jar cells) were hCG(+) by immunostaining, allowed to form spheroids, and confirmed to secrete hCG into the medium. Time-dependent experiments demonstrated a high rate of attachment of Jar spheroids to the epithelium, and adhesion was strongly related to the various cell types present in the 3D culture. An architecturally and functionally competent 3D endometrial culture system was established, that coupled with Jar spheroids mimicking trophoblast cells, provides a unique in vitro model for the study of certain aspects of human implantation.

Different ART outcomes at increasing peak estradiol levels with long and antagonist protocols: retrospective insights from ten years experience

PURPOSE

To evaluate the impact of high estradiol (E2) levels on assisted reproductive technologies outcomes in high responders (≥12 oocytes retrieved) according to the controlled ovarian stimulation protocol (COS) used.

METHODS

Clinical retrospective evaluation of total, clinical pregnancy and implantation rates in ART cycles performed in high responders according to the COS protocol used (long or antagonist) at Pathophysiology Unit of Human Reproduction and Sperm Bank of Pordenone from June 2000 to December 2010.

RESULTS

In high responders total, clinical and implantation rates were significantly higher in long if compared with antagonist protocol with peak estradiol level ≤3,000 pg/ml; on the contrary there was a significantly higher implantation rate with antagonist than long protocol with peak estradiol >3,000 pg/ml. However in this subgroup of patients total and clinical pregnancy rates showed only a trend favouring antagonist possibly due to a statistical β error.

CONCLUSIONS

In high responders long protocol seems to work better than antagonist when peak E2 is lower than 3,000 pg/ml but the opposite may be true for cycles with higher E2 levels.

Endometrial gene expression in the window of implantation is altered in obese women especially in association with polycystic ovary syndrome

OBJECTIVE

To determine whether luteal phase endometrial transcriptome is altered in obese women during the window of implantation (WOI), considering the presence of infertility, fat distribution and association with polycystic ovary syndrome (PCOS).

DESIGN

Prospective study.

SETTING

University-affiliated infertility clinic, between May 2007 and March 2009.

PATIENT(S)

One control group of women with normal weight (n=4), and four study groups of obese women (n=6 each one) according to the association with infertility, PCOS, and ovarian stimulation.

INTERVENTION(S)

The endometrium was biopsied 7 days after LH surge or hCG administration in 28 women.

MAIN OUTCOME MEASURE(S)

Endometrial gene expression during the WOI.

RESULT(S)

One hundred and fifty-one genes were dysregulated in obese groups compared with controls. This dysregulation was more pronounced when infertility was associated. The biologic processes of these genes belonged mainly to development and regulation of different biological functions such as transcription and biosynthesis. The molecular functions overrepresented were transcription and peptide receptor activity. The endometrium of obese women with PCOS showed dysregulated genes related to biologic processes such as development, morphogenesis, and the immune system, as well as different molecular functions such as protein binding, binding, growth factor activity, and carboxylic acid transmembrane transporter activity. Some of these genes have been previously related to implantation and unexplained infertility.

CONCLUSION(S)

Obese women present a different endometrial gene expression than controls during the WOI, which is more pronounced when infertility or polycystic ovary syndrome are associated.

Frozen-thawed blastocyst transfer reduces ectopic pregnancy risk: an analysis of single embryo transfer cycles in Japan

OBJECTIVE

To evaluate the effect of frozen-thawed blastocyst transfer on ectopic pregnancy (EP) rate.

DESIGN

Retrospective analysis.

SETTING

Japanese registry of assisted reproductive medicine.

PATIENT(S)

Women who were registered during 2008.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Rates of live birth, EP, and spontaneous abortion in single blastocyst and cleavage-stage ET cycles in both fresh and frozen-thawed were determined.

RESULT(S)

In the frozen-thawed single blastocyst transfer cycles, 84 EPs of 10,312 clinical pregnancies (0.81%) were reported. There were 25 EPs of 1,361 clinical pregnancies (1.8%) in fresh IVF single blastocyst transfer cycles and 19 of 1,352 (1.4%) in fresh intracytoplasmic sperm injection single blastocyst transfer cycles. The rate of EPs after frozen-thawed single blastocyst transfers varied between 0.56% and 0.97% after stratification by age group.

CONCLUSION(S)

Frozen-thawed blastocyst transfers have reduced EP rates significantly compared with fresh blastocyst transfers.

Endometrial morphology and modulation of hormone receptors during ovarian stimulation for assisted reproductive technology cycles

OBJECTIVE

To study the biochemical and morphologic implications of different hormonal levels on endometrial development during assisted reproductive technology (ART) cycles.

DESIGN

Prospective, controlled study.

SETTING

University center.

PATIENT(S)

Eleven women during a natural cycle (controls) and 11 oocyte donors during an ART cycle (treated).

INTERVENTION(S)

At the time consistent with day-3 ET, a transvaginal ultrasound, an endometrial biopsy, and blood sampling were performed. Morphology and thickness of the endometrial stripe were recorded. Real-time reverse transcriptase-polymerase chain reaction was used to measure messenger RNA (mRNA) levels for estrogen receptor (ER)-α, ER-β, P receptor (PR)-A, and PR-B in the endometrial tissue.

MAIN OUTCOME MEASURE(S)

To evaluate morphologic and biochemical endometrial development.

RESULT(S)

Endometrium was mostly trilaminar (proliferative-like pattern) and thicker in the treated group, as opposed to homogeneous and thinner in the controls. The PR-B mRNA expression increased 41% in treated patients; PR-A mRNA expression, instead, was unchanged. Serum E(2) and P were higher in the treated group than in controls. In contrast, FSH and LH levels were lower in the treated group.

CONCLUSION(S)

When compared with natural cycles, exposure of the endometrium to high hormone levels during ovarian stimulation significantly increased PR-B receptor expression at the time of ET. Concurrently, a proliferative-like endometrial pattern persisted. These findings reflect a delayed endometrial development in ART.

Milder is better? Advantages and disadvantages of "mild" ovarian stimulation for human in vitro fertilization

In the last decades, several steps have been made aiming at rendering human IVF more successful on one side, more tolerable on the other side. The "mild" ovarian stimulation approach, in which a lower-than-average dose of exogenous gonadotropins is given and gonadotropin treatment is started from day 2 to 7 of the cycle, represents a significant step toward a more patient's friendly IVF. However, a clear view of its virtues and defects is still lacking, because only a few prospective randomized trials comparing "mild" vs. conventional stimulation exist, and they do not consider some important aspects, such as, e.g., thawing cycles. This review gives a complete panorama of the "mild" stimulation philosophy, showing its advantages vs. conventional ovarian stimulation, but also discussing its disadvantages. Both patients with a normal ovarian responsiveness to exogenous gonadotropins and women with a poor ovarian reserve are considered. Overall, we conclude that the level of evidence supporting the use of "mild" stimulation protocols is still rather poor, and further, properly powered prospective studies about "mild" treatment regimens are required.

Lysophosphatidic acid up-regulates expression of growth-regulated oncogene-alpha, interleukin-8, and monocyte chemoattractant protein-1 in human first-trimester trophoblasts: possible roles in angiogenesis and immune regulation

The serum lysophospholipase D activity and production of lysophosphatidic acid (LPA) increase in women with pregnancy. The effects of LPA on human placenta tissue remained unclear. We investigate the expression of LPA receptors and function of LPA in human first-trimester trophoblasts. Normal villous trophoblasts were obtained from termination of first-trimester gestation. We examined the expression of LPA receptors in primary culture of trophoblasts and the tissue. The effects of LPA on the expressions of chemokines of trophoblasts were examined using RT-PCR and enzyme immunoassay. We delineate signal pathways of LPA-inducing relevant chemokines in trophoblasts. The secretory chemokines were tested for angiogenic function using human endometrial microvascular endothelial cells and for immunological chemotaxis using decidual natural killer cells and THP-1 monocytes. The results revealed the expression of LPA1 receptors in trophoblast cells. LPA enhanced growth-regulated oncogene (GRO)-alpha, IL-8 and monocyte chemoattractant protein (MCP)-1 expressions in a time- and dose-dependent manner. Mechanistic dissection disclosed that LPA functioned mainly via the LPA1 receptor, Gi protein, various signal mediators of ERK, protein kinase C, p38, Akt, and c-Jun N-terminal kinase, and nuclear factor-kappaB pathways to secrete these chemokines. LPA-induced IL-8 protein secretion of trophoblasts enhanced permeability, migration, proliferation, and capillary tube formation of human endometrial microvascular endothelial cells. LPA-induced GRO-alpha and MCP-1 incited chemotaxis of natural killer cells and monocytes. We demonstrate that LPA mediates trophoblast cells to produce GRO-alpha, IL-8, and MCP-1 via LPA1 receptors and nuclear factor-kappaB-dependent signal pathways. Through LPA-induced chemokine production, human first-trimester trophoblast cells may regulate angiogenesis and innate immune system in early pregnancy.

Excessive ovarian stimulation up-regulates the Wnt-signaling molecule DKK1 in human endometrium and may affect implantation: an in vitro co-culture study

BACKGROUND

High serum estradiol (E2) levels following ovarian stimulation lead to reduced implantation and pregnancy rates, yet the underlying mechanisms remain unknown. We investigated if aberrant expression of genes in the Wnt-signaling pathway may be involved.

METHODS

Microarray and real-time PCR analysis were performed to analyze gene expression profiles of endometrial samples taken at day hCG + 7 in stimulated cycles, and days LH + 7 and LH + 10 in natural cycles. Expression of several Wnt-signaling transcripts, including Dickkopf homolog 1 (DKK1), DKK2 and secreted frizzled-related protein 4 (sFRP4), was analyzed throughout the menstrual cycle. JAr spheroid/Ishikawa endometrial cell co-culture experiments were established to study effects of DKK1 on spheroid attachment in vitro.

RESULTS

We identified 351 differentially expressed genes. Endometrial samples taken at hCG + 7 had similar expression profiles to those at LH + 10. DKK1 transcripts were up-regulated and DKK2 and sFRP4 were down-regulated in the stimulated compared with LH + 7 group (all P < 0.05). DKK1 transcripts were low in proliferative phase (PS) and increased in late-secretory phase (LS, P < 0.05), although DKK2 peaked in mid-secretory phase (P < 0.05). sFRP4 transcripts were high in PS. Treatment of spheroid with recombinant human DKK-1 protein dose-dependently suppressed (P < 0.05 versus control) spheroids attachment onto endometrial cells (associated with decreased beta-catenin protein): this suppression was nullified by anti-DKK1 antibody.

CONCLUSION

Gene expression patterns in stimulated cycles resembled those of LS in natural cycles, when the implantation window is about to close, suggesting high serum E2 and/or progesterone concentrations may advance endometrial development, altering the implantation window and possibly decreasing pregnancy rate. Aberrant expression of DKK1 might impair embryo attachment and implantation in vivo.

Embryo cryopreservation rescues cycles with premature luteinization

OBJECTIVE

To determine whether embryo cryopreservation in cycles with elevated preovulatory P followed by thaw, extended culture, and transfer results in greater ongoing pregnancy rates than fresh blastocyst transfer.

DESIGN

Retrospective matched cohort study.

SETTING

Private fertility center.

PATIENT(S)

The study group consisted of 118 consecutive thaws of bipronucleate (2PN) oocytes derived from autologous cycles with elevated preovulatory P, resulting in 95 blastocyst transfers. The control group was selected by matching on the number of 2PN oocytes and patient age and consisted of 118 fresh cycles with elevated preovulatory P, including 108 fresh autologous blastocyst transfers. All patients were <41 years old at the time of stimulation.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Implantation and ongoing pregnancy rates.

RESULT(S)

The study group had significantly fewer blastocysts per 2PN oocyte than the control group (19.7% vs. 36.8%, respectively) and a significantly greater cancellation rate (19.5% vs. 8.5%, respectively). However, the ongoing pregnancy rate per cycle was significantly higher in the study group than in the control group (56.8% vs. 32.2%, respectively), resulting from greater rates of implantation (56.8% vs. 26.9%, respectively) and of ongoing pregnancy per transfer (70.5% vs. 35.2%, respectively).

CONCLUSION(S)

In cycles with elevated preovulatory P, the probabilities of implantation and ongoing pregnancy are increased if all 2PN oocytes are cryopreserved and subsequently thawed and cultured to the blastocyst stage before transfer.

Gene expression profile of human endometrial receptivity: comparison between natural and stimulated cycles for the same patients

BACKGROUND

The adjunction of exogenous hormones for controlled ovarian stimulation (COS) may alter endometrial receptiveness. In order to identify the genes misregulated under COS, we compared the endometrium gene expression profiles, from the same patients, in a natural cycle and in a subsequent COS cycle.

METHODS

For the same normal-responder patients (n = 21), endometrial biopsies (n = 84) were collected during the pre-receptive (LH + 2) and receptive stages (LH + 7) of a natural cycle and, subsequently, on oocyte retrieval day (hCG + 2) and on transfer day (hCG + 5) of a stimulated cycle. Samples were analyzed using DNA microarrays. Gene expression profiles and biological pathways involved in endometrial receptivity were analyzed.

RESULTS

Although endometrium transition profiles from pre-receptive to receptive phases are similar between patients, COS regimens alter endometrial receptivity in comparison with natural cycle. Under COS conditions, two endometrial profiles were identified and were associated either with a moderately altered receptivity profile for the majority of the patients or a strongly altered profile for a sub-category of patients. The receptive endometrium transcription profile under COS was defective for biological functions such as TGFbeta signaling, leukocyte transendothelial migration and the cell cycle.

CONCLUSIONS

Gonadotrophin treatments in COS cycles led to disruptions of the transcriptional activation of genes involved in normal endometrial receptivity. We propose that when the receptiveness of the endometrium is seriously compromised by the COS protocol, fresh embryo replacement should be cancelled, the embryo frozen and thawed embryo replacement should be performed under natural cycles.