Endometrial markers of uterine receptivity utilizing the donor oocyte model

Ovarian stimulation protocols: impact on oocyte and endometrial quality and function

Ovarian stimulation (OS) truly is an art. There exists a myriad of protocols used to achieve the same goal: stimulating the ovaries to produce more than one mature oocyte to improve the chance of a live birth. However, considerable debate remains as to whether OS impacts oocyte and endometrial quality to affect in vitro fertilization outcomes. Although "more is better" has long been considered the best approach for oocyte retrieval, this review challenges that notion by examining the influence of stimulation on oocyte quality. Likewise, improved outcomes after frozen blastocyst transfer suggest that OS perturbs endometrial preparation and/or receptivity, although correlating changes with implantation success remains a challenge. Therefore, the focus of this review is to summarize our current understanding of perturbations in human oocyte quality and endometrial function induced by exogenous hormone administration. We highlight the need for further research to identify more appropriate markers of oocyte developmental competence as well as those that define the roles of the endometrium in the success of assisted reproductive technology.

The metabolomic profile of endometrial receptivity in recurrent miscarriage

BACKGROUND

Endometrial receptivity has been the focus of continuous research for over eight decades; however, current clinical practice lacks an accurate test of endometrial receptivity to allow the prediction of successful pregnancy. We aimed to characterize the endometrial metabolomic profiles of women who suffered recurrent miscarriage using discovery metabolomics and to set the foundation for the development of an endometrial receptivity test.

METHODS

This was a prospective multicenter cohort study led by the Tommy's National Centre for Miscarriage Research in Birmingham. Endometrial biopsies were obtained during the window of implantation from 24 women aged 18-35 years, who were not pregnant and regularly menstruating, diagnosed with unexplained recurrent miscarriage. The metabolite composition and relative concentrations of samples were analyzed applying ultra-high performance liquid chromatography-mass spectrometry to investigate water-soluble and lipid metabolites.

RESULTS

Various metabolic perturbations are associated with observation of increased numbers of miscarriages. They relate to fatty acid metabolism including increased lipolysis and decreased medium chain fatty acid beta-oxidation, poorer mitochondrial health, and redox-active co-factors which are present at higher oxidative levels. Other metabolic perturbations are associated with observation of live birth following miscarriages. They relate to perturbed cholesterol-cholesterol sulphate metabolism, fatty acid metabolism including increased diacylglyceride lipolysis and decreased medium chain fatty acid beta-oxidation, and improved mitochondrial health.

CONCLUSIONS

The present endometrial metabolomics discovery studies have implicated a small number of metabolic pathways and biological functions which are biologically important in miscarriage mechanisms.

The density of endometrial glandular openings: a novel variable to predict the live birth rate in patients with intrauterine adhesions following hysteroscopic adhesiolysis

STUDY QUESTION

Can the density of endometrial glandular openings (DEGO) be a reliable and simple new variable in the prediction of live birth after hysteroscopic adhesiolysis?

SUMMARY ANSWER

The DEGO grade at follow-up hysteroscopy outperforms American Fertility Society (AFS) score in predicting the live birth rate after hysteroscopic adhesiolysis for patients with intrauterine adhesions (IUAs).

WHAT IS KNOWN ALREADY

Several methods, such as endometrial thickness and AFS score, have been proposed for predicting the live birth rate in patients with IUAs who undergo hysteroscopic adhesiolysis.

STUDY DESIGN, SIZE, DURATION

A test cohort of 457 patients with IUAs who underwent hysteroscopic adhesiolysis and had satisfactory follow-up hysteroscopy videos were retrospectively enrolled between January 2016 and January 2017. A validation cohort comprising 285 IUA patients was prospectively enrolled from March 2018 to August 2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

An automated counting software tested the follow-up hysteroscopy videos to calculate the DEGO grade of all the 742 patients with IUAs after hysteroscopic adhesiolysis. The AFS score for each patient was also calculated at the same follow-up hysteroscopy. Logistic regression analysis was performed to develop prediction models to predict the live birth rate following hysteroscopic adhesiolysis. The performance of each of these prediction models was compared by calculating the AUC.

MAIN RESULTS AND THE ROLE OF CHANCE

In the test cohort (n = 457), 231 patients had a live birth, but 226 patients failed. In the validation cohort (n = 285), 117 patients had a live birth, while 168 patients did not. The logistic regression analysis revealed that both the DEGO grade and AFS score at follow-up hysteroscopy were closely correlated with the live birth rate in patients with IUAs (P = 0). The AUCs of AFS score and DEGO grade in the test cohort were 0.7112 and 0.8498, respectively (P < 0.0001). The AUCs of AFS score and DEGO grade in the prospective external validation cohort were 0.6937 and 0.8248, respectively (P < 0.0001).

LIMITATIONS, REASONS FOR CAUTION

Further well-designed prospective clinical studies with a multicentric larger sample size should be needed to confirm the feasibility and efficacy of DEGO.

WIDER IMPLICATIONS OF THE FINDINGS

The DEGO grade is an accurate predictor factor of live birth rate in patients with IUAs following hysteroscopic adhesiolysis and can represent in the future an important and promising tool for assessing obstetric outcomes in IUAs.

STUDY FUNDING/COMPETING INTEREST(S)

This study is supported by National Key Research and Development Program of China (Grant No. 2018YFC1004800), Natural Science Foundation of China (Grant No. 81671492), Natural Science Foundation of Hunan (Grant No. 2020JJ5859). B.G. is supported by Chinese Scholarship Council (File number. 201806370178). The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A

Conventional and modern markers of endometrial receptivity: a systematic review and meta-analysis

BACKGROUND

Early reproductive failure is the most common complication of pregnancy with only 30% of conceptions reaching live birth. Establishing a successful pregnancy depends upon implantation, a complex process involving interactions between the endometrium and the blastocyst. It is estimated that embryos account for one-third of implantation failures, while suboptimal endometrial receptivity and altered embryo-endometrial dialogue are responsible for the remaining two-thirds. Endometrial receptivity has been the focus of extensive research for over 80 years, leading to an indepth understanding of the processes associated with embryo-endometrial cross-talk and implantation. However, little progress has been achieved to translate this understanding into clinically meaningful prognostic tests and treatments for suboptimal endometrial receptivity.

OBJECTIVE AND RATIONALE

The objective of this systematic review was to examine the evidence from observational studies supporting the use of endometrial receptivity markers as prognostic factors for pregnancy outcome in women wishing to conceive, in order to aid clinicians in choosing the most useful marker in clinical practice and for informing further research.

SEARCH METHODS

The review protocol was registered with PROSPERO (CRD42017077891). MEDLINE and Embase were searched for observational studies published from inception until 26 February 2018. We included studies that measured potential markers of endometrial receptivity prior to pregnancy attempts and reported the subsequent pregnancy outcomes. We performed association and accuracy analyses using clinical pregnancy as an outcome to reflect the presence of receptive endometrium. The Newcastle-Ottawa scale for observational studies was employed to assess the quality of the included studies.

OUTCOMES

We included 163 studies (88 834 women) of moderate overall quality in the narrative synthesis, out of which 96 were included in the meta-analyses. Studies reported on various endometrial receptivity markers evaluated by ultrasound, endometrial biopsy, endometrial fluid aspirate and hysteroscopy in the context of natural conception, IUI and IVF. Associations were identified between clinical pregnancy and various endometrial receptivity markers (endometrial thickness, endometrial pattern, Doppler indices, endometrial wave-like activity and various molecules); however, their poor ability to predict clinical pregnancy prevents them from being used in clinical practice. Results from several modern molecular tests are promising and further data are awaited.

WIDER IMPLICATIONS

The post-test probabilities from our analyses may be used in clinical practice to manage couples' expectations during fertility treatments (IUI and IVF). Conventionally, endometrial receptivity is seen as a dichotomous outcome (present or absent), but we propose that various levels of endometrial receptivity exist within the window of implantation. For instance, different transcriptomic signatures could represent varying levels of endometrial receptivity, which can be linked to different pregnancy outcomes. Many studies reported the means of a particular biomarker in those who achieved a pregnancy compared with those who did not. However, extreme values of a biomarker (as opposite to the means) may have significant prognostic and diagnostic implications that are not captured in the means. Therefore, we suggest reporting the outcomes by categories of biomarker levels rather than reporting means of biomarker levels within clinical outcome groups.

Clomiphene citrate impairs the endometrial CD98 expression in ovariectomized and non-ovariectomized rats: Role of HCG

Background

Clomiphene citrate (CC) is one of the widely used drugs as an ovulation stimulant, but its adverse effects on the endometrium results in lowering down the pregnancy rate. Endometrium CD98 is also important in the process of implantation.

Objective

To evaluate the immunohistochemistry expression levels of endometrial CD98 following injection of CC with and without Human chorionic gonadotropin (HCG) in ovariectomized and non-ovariectomized rats.

Materials and Methods

Seventy two (12-14 wk old) female Wistar rats were randomly divided into two groups (n = 36): (a) ovariectomized and (b) non-ovariectomized. Each group was further divided into six subgroups (n = 6/each): (1) CC 10 mg/kg, (2) CC 20 mg/kg, (3) HCG, (4) CC 10 mg/kg with HCG, (5) CC 20 mg/kg with HCG, and (6) control. The experimental subgroups received a single dose of CC (daily, five days) and HCG (after the last injection of CC) alone or in combination. Immunohistochemistry staining was performed on paraffin-embedded endometrial tissues to evaluate the expression levels of CD98.

Results

Animals undergoing ovariectomy presented a significantly lower expression level of endometrial CD98 (p < 0.001) when compared with non-ovariectomized in the same condition that groups were subdivided. There was also a dose-dependent reduction (p < 0.001) in the expression of CD98 in non-ovariectomized subgroups when compared with control group. In addition, injection of HCG following treatment with CC improved its expression.

Conclusion

It was concluded that CC impairs CD98 expression in endometrium and this impairment is intensified with the removal of the ovary. Also, an injection of HCG following treatment with CC can slightly improve the expression of CD98.

Decreased expression of aquaporin 2 is associated with impaired endometrial receptivity in controlled ovarian stimulation

Recently, there has been evidence of decreased implantation rates with in vitro fertilisation and embryo transfer due to controlled ovarian stimulation (COS). The aim of this study was to investigate the effect of COS on embryo implantation and the role of aquaporin 2 (AQP2). We recruited eight patients who underwent COS and 40 matched controls. Endometrial samples were collected on Day 4~8 after injection of human chorionic gonadotrophin in the COS group and in the mid-secretory phase in the control group. Human endometrial morphological changes after COS were examined and expression of AQP2, leukaemia inhibitory factor (LIF) and integrin B3 (ITGB3) were determined by quantitative polymerase chain reaction, western blotting and immunohistochemistry in human endometrium and Ishikawa cells. Attachment rates were obtained using the embryo attachment test. The results showed that endometrial epithelial cells from the COS group were disrupted and lacked pinopodes. Messenger RNA and protein levels of AQP2, LIF and ITGB3 decreased in endometrial samples from the COS group. Knockdown of AQP2 resulted in reduced expression of LIF and ITGB3 and reduced embryo attachment rates. In conclusion, impaired endometrial receptivity in patients who underwent COS is correlated with a decreased expression of AQP2.

Integrin beta 8 (ITGB8) regulates embryo implantation potentially via controlling the activity of TGF-B1 in mice

Integrins (ITGs) are mediators of cell-cell and cell-matrix interactions, which are also associated with embryo implantation processes by controlling the interaction of blastocyst with endometrium. During early pregnancy, ITGbeta8 (ITGB8) has been shown to interact with latent transforming growth factor (TGF) beta 1 (TGFB1) at the fetomaternal interface. However, the precise role of ITGB8 in the uterus and its association with embryo implantation has not been elucidated. Therefore, we attempted to ascertain the role of ITGB8 during the window of embryo implantation process by inhibiting its function or protein expression. Uterine plasma membrane-anchored ITGB8 was augmented at peri-implantation and postimplantation stages. A similar pattern of mRNA expression was also found during the embryo implantation period. An immunolocalization study revealed the presence of ITGB8 on luminal epithelial cells along with mild expression on the stromal cells throughout the implantation period studied; however, an intense fluorescence was noted only during the peri- and postimplantation stages. Bioneutralization and mRNA silencing of the uterine Itgb8 at preimplantation stage reduced the rate/frequency of embryo implantation and subsequent pregnancy, suggesting its indispensable role during the embryo implantation period. ITGB8 can also regulate the liberation of active TGFB1 from its latent complex, which, in turn, acts on SMAD2/3 phosphorylation (activation) in the uterus during embryo implantation. This indicates involvement of ITGB8 in the embryo implantation process through regulation of activation of TGFB1.

Endometrial gene expression reveals compromised progesterone signaling in women refractory to embryo implantation

BACKGROUND

Endometrial function is essential for embryo implantation. The aim of this study was to analyze gene expression profiles from individual endometrial samples obtained from women with repeated implantation failure after IVF in oocyte donation programs.

METHODS

Seventeen volunteers were recruited: women who had previously participated as recipients in oocyte donation cycles and repeatedly exhibited implantation failure (Group A, study group, n = 5) or had at least one successful cycle (Group B, control group, n = 6) and spontaneously fertile women (Group C, normal fertility group, n = 6). An endometrial cycle was induced with exogenous estradiol (E2) and progesterone (P) and an endometrial sample was collected on the seventh day of P treatment.

RESULTS

Transcriptome analysis showed 82 genes with consistent differential gene expression when comparing A vs. B and A vs. C. One hundred transcripts differentially expressed in group A vs. B have been shown to be regulated by P, suggesting compromised P signaling in the endometrium. The P receptor (PR) mutation PROGINS was not detected in women from group A. Semi-quantitation of immunoreactive PRA/B, PRB and Sp1 (a transcription factor related to P signaling) in paraffin-embedded endometrial sections, did not show statistically significant differences amongst groups. However immunostaining glycodelin was significantly decreased in endometrial samples from group A.

CONCLUSIONS

We conclude that some cases of repeated implantation failure could be associated with an aberrant gene expression profile. Compromised P signaling might be the underlying mechanism for such endometrial gene expression deregulation in women with repeated implantation failure.

Glycodelin in reproduction

To achieve a successful pregnancy in humans, sperm is required for capacitation, followed by binding to and entry into an oocyte. Maternal endometrial epithelial cells (EECs) prepare the appropriate implantation environment through regulation of immune cells and endometrial cells. After acquiring endometrial receptivity, a successful pregnancy consists of complex and finely regulated steps involving apposition, adhesion, invasion, and penetration. Glycodelin is a secretory glycoprotein that affects cell proliferation, differentiation, adhesion, and motility. Glycodelin has four glycoforms (glycodelin-A, -S, -F. and -C); differences in glycosylation affect each characteristic function. Glycodelin has a unique temporospatial pattern of expression, primarily in the reproductive tract where glycodelin is mid-secretory phase-dominant. Recent studies have demonstrated that glycodelin protein has the potential to regulate various processes, including immunosuppression, fertilization, and implantation. This review details the orchestrated regulation of successful pregnancy by glycodelin as well as a discussion of the basic characteristics of glycodelin.

Effects of hydrosalpinx on pinopodes, leukaemia inhibitory factor, integrin beta3 and MUC1 expression in the peri-implantation endometrium

OBJECTIVES

To compare the expression of pinopodes, LIF, integrin beta(3) and MUC1 in the peri-implantation endometrium of women with and without hydrosalpinx.

STUDY DESIGN

A prospective observational study in an assisted reproductive unit in a university teaching hospital, including 20 women with hydrosalpinx and 21 women without hydrosalpinx. Endometrial biopsies were performed on day LH+7 or +8. The proportion and density of pinopodes were assessed by scanning electron microscopy. LIF, integrin beta3 and MUC1 were evaluated with immunohistochemical staining.

RESULTS

The proportion and the density of pinopodes were not significantly different between the hydrosalpinx and control groups. The LIF, integrin beta(3), and MUC1 expression were significantly reduced in both glandular epithelial cells and endometrial lumen of the hydrosalpinx group when compared with those of the control group. The expression of integrin beta(3) in stromal cells was also significantly lower in the hydrosalpinx group.

CONCLUSIONS

The proportion and the density of pinopodes in the peri-implantation endometrium were not affected by the presence of hydrosalpinx while LIF, integrin beta(3) and MUC1 were significantly reduced in patients with hydrosalpinx.

Asian ethnicity in anonymous oocyte donors is associated with increased estradiol levels but comparable recipient pregnancy rates compared with Caucasians

OBJECTIVE

To determine if differences exist in ovarian response and pregnancy rates between Asian and Caucasian donors.

DESIGN

Retrospective cohort study.

SETTING

University-based clinic.

PATIENT(S)

Anonymous oocyte donors of self-reported Asian (n=63) or Caucasian (n=156) ethnicity who began ovarian stimulation between February 2000 and March 2008 and their matched recipients.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Recipient pregnancy rates and oocyte donor ovarian responsiveness.

RESULT(S)

Baseline characteristics were similar between Asian and Caucasian donors. Asian donors had peak serum estradiol levels that were 23% higher than their Caucasian counterparts (3715±220 vs. 3013±114 pg/mL). Adjusted estradiol levels per follicle measured and per oocyte retrieved were elevated in Asian donors (17% and 23% higher, respectively), and these differences were unchanged after adjusting for body mass index. No differences were noted in implantation rates (47.4% vs. 40.9%), clinical pregnancy rates (60.3% vs. 62.4%), or live-birth rates (55.5% vs. 59.9%) achieved using Asian vs. Caucasian oocyte donors.

CONCLUSION(S)

In contrast to autologous fresh in vitro fertilization cycles, Asian ethnicity is not associated with a lower pregnancy rate in recipient women using controlled hormone replacement when anonymous donor oocytes are used. Asian donors achieved statistically significantly higher serum estradiol levels during gonadotropin stimulation, suggesting an ethnic difference in steroid production and/or metabolism.

Calcium-binding protein S100P is highly expressed during the implantation window in human endometrium

OBJECTIVE

To investigate S100P expression and localization in human endometrium throughout the menstrual cycle.

DESIGN

Experimental study.

SETTING

University hospital.

PATIENT(S)

Eighty-four women.

INTERVENTION(S)

Complementary DNA (cDNA) microarray analysis was performed on human endometrium from days LH+4, LH+7, and hCG+7. Reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis were used to detect the expression of S100P and of additional S100 family members, S100A4, S100A13, and S100A6. Immunofluorescence was used to detect the localization of S100P protein in LH+7 and LH+4 endometrium.

MAIN OUTCOME MEASURE(S)

Differential gene expression, levels of S100P messenger RNA (mRNA), and protein expression and immunofluorescent localization of S100P.

RESULT(S)

A statistical method, based on hierarchical clustering, identified genes whose expression varied at LH+7 compared with LH+4. We found that S100P was the fourth most up-regulated gene at LH+7. The S100P mRNA and protein levels were quite low during the proliferative phase and LH+4, but were elevated significantly at LH+7. The S100P expression at hCG+7 was lower than that at LH+7. However, the expression of S100A4, S100A13, and S100A6 did not vary throughout the menstrual cycle.

CONCLUSION(S)

S100P was specifically up-regulated during the implantation window. The underlying biological effects of S100P need further exploration.

Impact of high levels of progesterone on alpha(1)-integrin distribution in the endometrium of patients with unexplained infertility

Irregular or low expression of integrins, which are cell adhesion molecules, may be associated with infertility. We conducted a prospective controlled study evaluating the effects of supraphysiological levels of estrogen and progesterone created by human menopausal gonadotropins (HMG) and progesterone support on alpha(1)-integrin immunolocalisation in the endometrium. Three groups were enrolled in the study. The first group of patients (group 1) had unexplained infertility and had been treated with HMG and progesterone (n=27). The second group of patients (group 2) was an untreated fertile group (n=24). The third group (group 3) consisted of patients who had unexplained infertility and had received no treatment (n=11). Endometrial biopsy specimens were taken from individuals from each group during the ovulation induction period. alpha(1)-integrin immunohistochemistry was performed. Serum estradiol and progesterone levels were also measured in parallel with histological dating of endometrial biopsies. Group 1 showed no statistical difference from group 2 in alpha(1)-integrin or histological dating. Group 3 showed less alpha(1)-integrin in the glandular epithelium in the secretory phase. We observed that alpha(1)-integrin was specific to the secretory phase. Its localization was denser in group 2 when compared with group 3, which supports the conclusion that alpha(1)-integrin may be a useful marker for luteal phase quality. Moreover, the supraphysiological estrogen and progesterone levels created by HMG and progesterone support may affect the alpha(1)-integrin in the endometrium in the secretory phase in the case of unexplained infertile patients.

Osteopontin and alphavbeta3 integrin expression in the endometrium of infertile and fertile women

Osteopontin and its receptor alpha(v)beta(3) integrin have recently been proposed as a major complex to promote embryo attachment, and thus they would be useful as markers of endometrial receptivity. In the current study alpha(v)beta(3) integrin and osteopontin expression and co-expression in in-phase and out-of-phase endometrial biopsies from normal healthy women (n = 12) and infertile patients (n = 107) were investigated. Two endometrial biopsies (post-ovulatory day +6 to +8, and 4 days later) were performed during a single menstrual cycle in each subject. Oestradiol and progesterone serum concentrations were quantified on the same days as endometrial sampling. No statistically significant difference regarding alpha(v)beta(3) integrin and osteopontin expression and their coexpression was found between fertile controls and infertile patients irrespective of endometria being in-phase or out-of-phase, infertility factors detected or whether patients became spontaneously pregnant or not. Although a co-ordinate high concentration of both glycoproteins on post-ovulatory day 8 onwards was observed, there was an evident lack of temporal co-expression of these markers during the implantation window. It is concluded that the functional significance of the osteopontin:alpha(v)beta(3) integrin complex as a marker of endometrial receptivity and implantation potential in women seems to be untenable.

Effects of ovarian stimulation on endometrial integrin β3 and leukemia inhibitory factor expression in the peri-implantation phase

OBJECTIVE

To investigate the effects of ovarian stimulation on endometrial receptivity in the peri-implantation phase.

DESIGN

Comparison of integrin beta3 and leukemia inhibitory factor (LIF) expression in endometrial biopsies from moderate responders and high responders with temporally matched natural cycles.

SETTING

Clinical and experimental research.

PATIENT(S)

Patients with cancelled embryo transfer were evaluated. Moderate responders were defined as E2 5,000-15,000 pmol/L on the day of hCG administration (group B, n = 7). High responders were defined as E2 >15,000 pmol/L on the day of hCG administration (group C, n = 8). Healthy and fertile volunteers were used as natural controls (group A, n = 10).

INTERVENTION(S)

Endometrial biopsy on the day of LH+7/hCG+7.

MAIN OUTCOME MEASURE(S)

Immunohistochemistry of integrin beta3 and LIF and imaging analysis.

RESULT(S)

Endometrial integrin beta3 and LIF expressions in the peri-implantation phase were significantly lower in stimulated cycles (including both moderate and high responders) compared to natural controls. Expression of LIF in glandular epithelium in high responders was lower than that in moderate responders.

CONCLUSION(S)

These data demonstrated that suggested markers of endometrial receptivity were reduced in stimulated cycles compared with natural cycles, and more so in high response cycles compared with moderate response cycles.

Morphometric study of GnRH analog/HMG/HCG effects on ultrastructure of human endometrial epithelium in early and mid-luteal phase

AIM

The aim of the present study was to investigate the effects of long protocol ovulation induction on the ultrastructure of the human endometrial epithelium on days luteinizing hormone (LH) + 4 and LH+ 6 of the menstrual cycle.

METHODS

Endometrial biopsies were obtained on days LH+ 4 (n = 9) and LH+ 6 (n = 10) from infertile women who were under standard long protocol with luteal phase supplementation with IM (intramuscular) progesterone, but where the embryo had not been formed or transferred, due to the male factor problem. Biopsies were also taken on days LH+ 4 (n = 5) and LH+ 6 (n = 5) from fertile women who had not received ovulation induction drugs as control groups. After preparation and taking light and electron micrographs from samples, qualitative and quantative evaluations (morphological and morphometric) were accomplished and the data was compared using the unpaired student t-test.

RESULTS

Qualitative results showed the presence of the nuclear channel system, vacuoles of glycogen and giant mitochondria in all of the samples. Qualitative analysis showed that the volume fraction (Vv) of the euchromatin to the nucleus, the rough endoplasmic reticulum and the mitochondria to the cell, were not statistically different (P > 0.05) in samples taken on LH+ 4 in both control and test groups. The Vv of these features, however, to the cell in the test group was significantly (P < 0.05) higher than those in the control taken on LH+ 6.

CONCLUSIONS

These results suggest that long protocol ovulation induction with luteal phase support with progesterone alter the normal development of the human endometrium in the mid luteal phase and could decrease the implantation success rate.

Glycosylation related actions of glycodelin: gamete, cumulus cell, immune cell and clinical associations

Glycodelin is an example of a glycoprotein whose complex-type glycans mediate biological actions in human reproduction and immune reactions. Being attached to an identical protein backbone, glycodelin oligosaccharides vary significantly from one reproductive tissue to another and have an effect on its own secretion and role in cell communication. For instance, uterine glycodelin-A inhibits sperm-oocyte interaction by binding on the sperm head. This is a glycosylation-dependent phenomenon, in which fucosyltransferase-5 plays a key role. Glycodelin-S from seminal plasma binds evenly around the sperm head and maintains an uncapacitated state in the spermatozoa, until the isoform is detached during sperm passage through the cervix. Glycodelin-F from follicular fluid and Fallopian tube binds to the acrosomal region of the sperm head, thereby inhibiting both the sperm-oocyte binding and premature progesterone-induced acrosome reaction. The cumulus cells surrounding the oocyte can capture glycodelin-A and -F from the surrounding environment and convert these isoforms to a cumulus cell isoform, glycodelin-C. It differs by glycosylation from the other isoforms, and it too attaches on the sperm head, with the highest density in the equatorial region. Glycodelin-C is capable of detaching the sperm-bound inhibitory isoforms so that the sperm-oocyte binding is enhanced. Glycodelin-A also has immunosuppressive actions directed to cellular, humoral and innate immunity. Although these actions depend mainly on the protein backbone, glycosylation also plays a part. Glycosylated glycodelin may be involved in the protection of spermatozoa against maternal immune reactions, and glycodelin also has apoptogenic activity. Some glycosylation patterns of glycodelin may mask its apoptogenic domain. This review updates the recent research and clinical associations of glycodelin, highlighting the role of glycosylation.

Effect of atosiban on rabbit embryo development and human sperm motility

OBJECTIVE

To investigate embryotoxic potential and effects on human sperm motility of the mixed vasopressin V(1a)/oxytocin receptor antagonist atosiban considered for novel indication of improvement of uterine receptivity in embryo-transfer recipients.

DESIGN

One-cell rabbit embryo bioassay and human sperm motility bioassay were performed in control media or in media containing atosiban.

SETTING

Private center of reproductive medicine and academic research institute of reproduction biotechnology.

ANIMAL(S)

Rabbit females (New Zealand and California, N = 15) aged 4.5-6.5 months.

INTERVENTION(S)

In vitro exposure of one-cell rabbit embryos and human sperm to atosiban in the range of therapeutic concentrations clinically occurring in human beings.

MAIN OUTCOME MEASURE(S)

Embryo development and sperm motility.

RESULT(S)

Preimplantation development of one-cell rabbit embryos was not affected by atosiban in the concentrations < or =15,000 nM, which was 50-fold higher than the mean plasma concentration reached during regular therapy (300 nM). Atosiban did not affect human sperm motility in concentrations of < or =3,000 nM, in other words, 10 times the human mean plasma concentration.

CONCLUSION(S)

Clinical application of atosiban in the proposed indication may be safe for embryos because it is compatible with preimplantation rabbit embryo development and human sperm motility.

Biomarkers of ovulation, endometrial receptivity, fertilisation, implantation and early pregnancy progression

Increasing interest in early preconception and periconception exposures and human developmental outcomes has led to studies that monitor subjects from before conception to gestation, birth and childhood. Monitoring ovulation, endometrial receptivity, fertilisation, implantation and gestation requires the non-invasive collection of biological information and samples, and the measurement of biochemical and biological markers (biomarkers) that are associated with the aforementioned physiological events. This paper describes some of the key features of biomarkers needed for epidemiological studies, identifies some existing and potential biomarkers and available measurement devices, and suggests some directions for identification and development of new biomarkers that might be employed in longitudinal studies involving the analysis of female reproductive function and of embryonic development.

Immunohistochemical expression of endometrial L-selectin ligand is higher in donor egg recipients with embryonic implantation

OBJECTIVE

To correlate L-selectin ligand (LSL) expression in human endometrium with embryonic implantation.

DESIGN

Retrospective cohort analysis.

SETTING

University-based fertility center.

PATIENT(S)

Donor egg recipients (DERs) who underwent programmed hormonal replacement for ET with prior mock cycle luteal phase endometrial biopsy.

INTERVENTION(S)

Immunohistochemical expression of LSL using MECA-79 antibody was examined. Slides were scored with a new scoring system, the IHC-Level (range 0-4) as follows: strength of staining-absent (0), weak (1), or strong (2); plus distribution of staining-absent (0), <50% of tissue (1), and >50% (2). Cellular apex and cytoplasm were scored independently in both the endometrial glandular and surface epithelium.

MAIN OUTCOME MEASURE(S)

Endometrial LSL expression in pregnant versus nonpregnant patients.

RESULT(S)

MECA-79 IHC-Level of the apex of surface epithelium was significantly higher for pregnant versus nonpregnant DERs (3.8 vs. 3.4). When controlling for embryo morphology, there continues to be a significant difference in apex score on surface epithelium (3.8 vs. 3.3, respectively). The new scoring system results correlated with an established scoring system, the HSCORE.

CONCLUSION(S)

We demonstrate significantly higher expression of LSL at the apex of human endometrial surface epithelium obtained from DERs with embryonic implantation. Furthermore, we present the IHC-Level, a method of evaluating immunohistochemistry that may be applied to other markers of endometrial receptivity.

Estradiol production during controlled ovarian hyperstimulation correlates with treatment outcome in women undergoing in vitro fertilization–embryo transfer

OBJECTIVE

To study the value of E(2) production during controlled ovarian hyperstimulation (COH) in predicting IVF-ET outcome.

DESIGN

Historical cohort.

SETTING

Academic infertility center.

PATIENT(S)

A cohort of 270 patients who completed 324 consecutive IVF-ET treatment cycles.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Area under the curve for E(2) levels (AUC-E(2)) from the first day of COH until the day of hCG administration was calculated and cycles grouped into low, average, and high AUC-E(2) groups. Clinical pregnancy rates per cycle were compared among the three groups, and correlations with AUC-E(2) values were calculated for all patients and after sub-grouping according to age, COH protocol and infertility diagnosis.

RESULT(S)

Cycles with low and high AUC-E(2) values had significantly lower pregnancy rates particularly in patients 35 years or older. There was a positive correlation between AUC-E(2) and pregnancy rates up to a certain AUC-E(2) level above which a negative correlation was found. The turning point between positive and negative correlations occurred at a significantly lower AUC-E(2) level in patients 35 years or older.

CONCLUSIONS

Estradiol production during COH correlates with IVF-ET outcome. Women >35 years of age seem more vulnerable to high E(2) levels.

Large-scale gene expression studies of the endometrium: what have we learnt?

The endometrium is a dynamic tissue that undergoes coordinated changes under the influence of steroid hormones. This results in proliferation and differentiation culminating in a receptive state, followed by menstruation and endometrial repair. These functions involve complex interactions between the epithelium, stroma and leucocytes in the endometrium. Understanding the underlying causes of endometrial disorders, such as infertility, endometriosis and heavy menstrual bleeding, therefore represents a considerable challenge. Recently developed techniques, such as differential display and DNA microarrays permit the abundance of thousands of mRNA transcripts within cells or tissues to be measured simultaneously. This provides a new approach to understanding the complex interactions that underlie both healthy and disease states. Responses of the endometrium to hormones or drugs can be studied and the response of the system as an integrated whole can be assessed. Comparisons of endometrium from healthy women and those with endometrial dysfunction have advanced our understanding of key areas of endometrial physiology, including infertility, receptivity, endometriosis and cancer. Using this approach, novel genes controlling specific endometrial functions like receptivity have been identified for functional testing. This paper will review the impact of these techniques for transcript profiling on our understanding of selected areas of endometrial biology and discuss the potential applications in future.

Ovarian stimulation with GnRH agonist, but not GnRH antagonist, partially restores the expression of endometrial integrin 3 and leukaemia-inhibitory factor and improves uterine receptivity in mice

BACKGROUND

The impact of different ovarian stimulation (OS) protocols on endometrial receptivity remains controversial. In this study, the effects of different OS on the expression of endometrial integrin beta3 subunit and leukaemia-inhibitory factor (LIF) during the implantation window and the implantation rate in mice were investigated.

METHODS

Three OS protocols were used, involving either pregnant mare's serum gonadotrophin (PMSG) alone, PMSG plus GnRH agonist or PMSG plus GnRH antagonist. Uterus samples were collected at 48 h after OS or ovulation and were detected with immunohistochemistry, Western blot and RT-PCR analyses. Normal embryos at gestation day 4 were transferred into the uteri of mice in the control and OS groups.

RESULTS

All OS groups showed a significant decrease in the expression of both the endometrial integrin beta3 subunit and LIF during the implantation window and the implantation rate. Among the three OS groups, GnRH agonist-treated mice showed a higher endometrial integrin beta3 subunit and LIF expression and a higher implantation rate. No significant difference was found in the measured indices between the GnRH antagonist and PMSG groups.

CONCLUSIONS

OS may inhibit the expression of endometrial integrin beta3 subunit and LIF and impair endometrial receptivity in mice. OS with GnRH agonist, but not GnRH antagonist, may partially restore the endometrial physiological secretion and improve uterine receptivity.

Oocyte and embryo donation 2006: reviewing two decades of innovation and controversy

For over 21 years, oocyte and embryo donation have been used to treat infertility caused by a variety of conditions affecting the ovary. Many disorders, including premature ovarian failure, advanced reproductive age, unexplained recurrent implantation failure and inherited conditions, are amenable to gamete donation, with high pregnancy rates and good obstetrical outcomes observed in recipients. Protocols for the medical screening of recipients and donors, as well as infectious disease and genetic testing, have become relatively uniform and well accepted. Established guidelines allow synchronization of the menstrual cycles of both women to ensure that embryos are transferred to a receptive endometrium. The high demand for donor services has led to escalating costs and long waiting lists. American programmes bid against each other to secure the participation of young women often motivated as much by financial reward as altruism. In the United States, where the majority of oocyte donation is practised, more than 100,000 treatment cycles have occurred. However, to date no meaningful longitudinal studies detailing the long term effects of treatment on donors, recipients, children born, or families created have been published. Throughout its history, oocyte and embryo donation has proven to be both efficacious and clinically innovative, yet remains highly controversial.

Endometrial receptivity: Clinical assessment in relation to fertility, infertility, and antifertility

Fertility in humans and other mammalian species depends absolutely on synchronous events that render the developing blastocyst and the receiving uterus competent for implantation. Endometrial receptivity is defined as the period during which the endometrial epithelium acquires functional, but transient, ovarian steroid-dependent status supportive to blastocyst acceptance and implantation. Once inside the uterus, the blastocyst is surrounded by an intact luminal epithelium, which is considered to act as barrier to its attachment, except for this short period of high endometrial receptivity to blastocyst signal(s). Its transport and permeability properties, in conjunction with cellular action of the endometrium and the embryo, have been suggested to influence creation and maintenance of informational and nutritional status of uterine luminal milieu. This period, also termed as the 'window of implantation,' is limited to days 20-24 of menstrual cycle in humans. However, establishment of endometrial receptivity is still a biological mystery that remains unsolved despite marked advances in our understanding of endometrial physiology following extensive research associated with its development and function. This review deals with various structural, biochemical, and molecular events in the endometrium coordinated within the implantation window that constitute essential elements in the repertoire that signifies endometrial receptivity and is aimed to achieve a better understanding of its relationship to fertility, infertility, and for the development of targeted antifertility agents for human use and welfare.

Is endometrial apoptosis evidence of endometrial aging in unexplained infertility? a preliminary report

OBJECTIVE

To investigate spontaneous endometrial apoptosis in women with unexplained infertility and to find out whether there is a possible relationship between endometrial apoptosis, age, and hormonal parameters.

STUDY DESIGN

This study was designed as a prospective, case-controlled study in a University Hospital setting. A total of 34 endometrial biopsies were performed from 17 women with unexplained infertility and 17 fertile controls, who were admitted for tubal ligation. Endometrium was sampled on the seventh post-ovulatory day. On the same day of endometrial sampling, serum levels of FSH, LH, PRL, TSH, E2, progesterone, 17alpha-hydroxyprogesterone, testosterone and DHEA-S were determined. Endometrial glandular and stromal apoptosis were investigated by DNA nick end labeling (TUNEL) method on each sample. Endometrial apoptotic index was calculated and correlated with age and hormonal parameters.

RESULTS

There was no difference in either endometrial glandular apoptotic index (AI) or stromal AI between the groups. However, the mean glandular AI was significantly higher than the mean stromal AI (p = 0.0001). There was a strong correlation between endometrial AI and age (r = 0.91, p = 0.02). Serum T levels were significantly found to be decreased in the unexplained infertility group (p = 0.0001). In addition, serum TSH levels were positively correlated with AI in the glandular endometrium in women with unexplained infertility (r = 0.611, p = 0.009).

CONCLUSION

Endometrial apoptosis increases with age. Serum levels of testosterone were lower in unexplained infertility. The effect of serum TSH levels on apoptosis in the glandular epithelium of the endometrium needs further studies.

Endometrial evaluation in superovulation programs: relationship with successful outcome

It is well known that an adequate endometrial receptivity is required for successful implantation in both natural and assisted reproductive cycles. In particular, a brief "implantation window", during which endometrium undergoes anatomical and molecular changes necessary for embryo implantation, has been observed. The hormonal treatment applied to induce ovulation seems to be able to modify the normal development of the prenidatory endometrium, with possible negative effect on the implantation rate. For this reason, several attempts have been made to identify specific markers of endometrial receptivity, useful for predicting implantation outcome in clinical practice. Even if different histological, immunohistochemical, and ultrasonographic parameters are studied, none unfortunately has been univocally shown to be predictive of pregnancy outcome. Therefore, the evaluation of endometrial receptivity remains a challenge in clinical practice.

Advances in uterine protein research: reproduction and cancer

Uterine protein research has advanced from the measurements of specific compounds to detailed analysis of the genes that regulate protein synthesis and build up the complex carbohydrate structures that play important functional roles. Some 80% of all human proteins are glycoproteins. Functional glycomics highlights the importance of glycosylation in glycoprotein function. Glycodelin is a representative example of functional glycomics because its various glycoforms have different functions. In the uterus, synthesis of glycodelin-A is temporally regulated by progesterone. During the estrogen-dominated fertile window, absence of glycodelin synthesis is significant because uterine glycodelin-A potently and dose-dependently inhibits sperm-egg binding, the initial step in fertilization. The anti-fertilization propensity of glycodelin-A during the luteal phase of the cycle is highly glycosylation-dependent, and there is an intricate functional interplay between spermatozoa, zona pellucida and the various glycodelin isoforms present in the uterine fluid, seminal plasma and follicular fluid, respectively. Endometrial glycodelin synthesis can be induced during the fertile window by administration of progestagens, such as in levonorgestrel hormone-releasing IUD and contraceptive implants. Glycodelin can be chemically modified in such a fashion that it blocks the binding site on CD4 for the HIV surface glycoprotein, synthesis of viral gp 120, and infection of peripheral blood mononuclear cells by the primary HIV isolate THA/93/051, thus potentially inhibiting HIV transmission. Now that a cell line producing the contraceptive isoform has been identified by recombinant technology, these findings may have application for locally applied antiviral contraception. Glycodelin also has immunosuppressive properties, suggesting that the recognition mechanisms in immune and reproductive systems may have converged. Given its inhibitory activity on natural killer cells, abundant at the fetomaternal interphase, the high glycodelin concentration at the same site suggests a role in fetomaternal defense mechanisms. This may be relevant in women with recurrent miscarriage, in whom both the serum and uterine fluid glycodelin concentrations are decreased. Experiments on cancer cell lines have demonstrated increased epithelial differentiation by glycodelin cDNA transfection, and also by co-culture of cancer cells with normal stromal cells in the presence of basement membrane components. Both approaches result in glycodelin expression concomitant with decreased cell proliferation and reversion of the malignant phenotype. These results suggest an active role of normal stromal cells, basement membrane components and glycodelin in epithelial differentiation and glandular morphogenesis. This disposition of glycodelin is significant in patients with certain carcinomas, in which glycodelin-expressing tumors carry better prognosis than glycodelin-negative tumors of the same clinical stage and histological grade. Research on functional glycomics continues to produce significant information on fundamental aspects of fertilization, implantation, pregnancy and cancer.

Body mass index and uterine receptivity in the oocyte donation model

OBJECTIVE

To evaluate the relationship of body mass index (BMI) to uterine receptivity under conditions of programmed hormonal support and standardized embryo quality.

DESIGN

Retrospective cohort study.A tertiary referral center.

PATIENTS

Ninety-seven consecutive first-cycle recipients of anonymous oocyte donation. After programmed hormone replacement, recipients had transfer of embryos derived from oocyte donation. Anonymous oocyte donors received ovarian stimulation and underwent transvaginal ultrasound-guided oocyte retrieval.

SETTING

A receiver operator characteristic (ROC) curve of implantation versus BMI. Area under the ROC curve was 0.51, 95% confidence interval (CI) 0.41-0.62, suggesting no relationship between BMI and implantation. There was no difference in implantation rates between obese (BMI >or=30) and nonobese (BMI <30) recipients, odds ratio 1.1, 95% CI 0.5-2.4.

CONCLUSION(S)

Uterine receptivity was unimpaired in women with increased BMI when hormonal support and embryo quality were standardized.

Factors that determine discordant outcome from shared oocytes

OBJECTIVE

To investigate the factors that may be related to pregnancy in oocyte recipients who shared oocytes from the same donor and showed discordant pregnancy outcome.

DESIGN

Matched pair analysis.

SETTING

IVF academic center.

PATIENT(S)

Five hundred forty-two oocyte donation cycles that shared oocytes from 197 donors with discordant outcome.

INTERVENTION(S)

Egg donation and embryo transfer.

MAIN OUTCOME MEASURE(S)

Pregnancy rate and implantation rate.

RESULT(S)

Three hundred sixty-five matched-paired discordant outcome oocyte recipients were analyzed. Pregnant and nonpregnant recipients were similar in terms of age, serum E(2) levels, endometrial thickness, indications for oocyte donation, and abnormal sperm parameters. No differences were found in the number of oocytes received per patient, fertilization rate, IVF/intracytoplasmic sperm injection (ICSI) distribution, embryo quality, or on embryo transfer difficulty.

CONCLUSION(S)

Discordant pregnancy outcome could not be explained by the different egg recipients and cycle factors studied. In addition to chance, other factors must be investigated that could explain discordant outcome in egg recipients sharing oocytes from single donors.

A combined approach for gene discovery identifies insulin-like growth factor-binding protein-related protein 1 as a new gene implicated in human endometrial receptivity

In the past, human endometrial receptivity has been investigated by chasing specific molecules throughout the menstrual cycle. Now the genomic approach allows us to investigate the hierarchical contribution of a high number of genes to a specific function. In this study, we analyzed differentially the gene expression pattern of 375 human cytokines, chemokines, and related factors, plus that of their receptors, in endometrial receptivity. To do this, we used a combined approach of human endometrium and cell lines. We have compared the gene expression pattern in receptive vs. prereceptive human endometria and contrasted the results with gene expression in the highly adhesive cell line (to JAR cells and mouse blastocysts) RL95-2 vs. HEC-1A, a cell line with markedly less adhesiveness. IGF-binding protein-related protein 1 (IGFBP-rP1), also known as IGFBP-7/mac 25, was the second most up-regulated gene in both of the investigated models. These results were corroborated by performing RT-PCR on the same RNA samples and validated by quantitative fluorescent RT-PCR and in situ hybridization in endometrium throughout the menstrual cycle. Interestingly, a 35-fold increase in expression during the receptive phase was compared with the prereceptive phase followed by a sharp increase in the late luteal. Further quantitative fluorescent RT-PCR experiments using the epithelial and stromal endometrial fraction throughout the menstrual cycle confirmed that IGFBP-rP1 expression was localized in the epithelial and stromal compartments and up-regulated mainly in the latter. In situ experiments confirmed the endometrial localization and regulation of IGFBP-rP1 mRNA. At the protein level, IGFBP-rP1 was localized by immunohistochemistry at the apical part of the luminal and glandular epithelium, stromal, and endothelial cells. In conclusion, using a genomic approach with a combined experimental design of receptivity in vivo and in vitro, we have discovered the implication of IGFBP-rP1 in endometrial physiology, which seems related to endometrial receptivity.

The endometrium as a cause of implantation failure

One of the biggest obstacles to reproductive success is our inability to diagnose or treat effectively the non-receptive endometrium. The endometrium becomes receptive for a limited period of time under the influence of steroid hormones and paracrine signals from the developing embryo. It is likely that the receptive state is characterized by the expression of particular genes that allow the normally refractory endometrium to respond to the embryo and permit attachment. Recently, several molecules have been reported whose function is essential for uterine receptivity in rodents and primates. This article will review current models of the control of receptivity and early implantation and assess progress in defining markers for the receptive endometrium in women. Although some genes have been identified whose expression is altered in women with subfertility, none of these molecular markers have yet proven clinically useful in the assessment of functional receptivity. The use of high throughput techniques such as microarrays and proteomic methods to investigate gene expression in the endometrium provides a novel approach to defining receptivity at the molecular level. The potential impact of these tools on clinical practice will be discussed.

Glycodelin: a major lipocalin protein of the reproductive axis with diverse actions in cell recognition and differentiation

Glycodelin is a glycoprotein that belongs to the lipocalin superfamily. Depending on glycosylation, glycodelin appears in various isoforms. In the uterus, glycodelin-A is the major progesterone-regulated glycoprotein secreted into uterine luminal cavity by secretory/decidualized endometrial glands. The other tissues expressing glycodelin include fallopian tubes, ovary, breast, seminal vesicle, bone marrow, and eccrine glands. Glycodelin-A potently and dose-dependently inhibits human sperm-egg binding, whereas differently glycosylated glycodelin-S from seminal plasma has no such effect. Absence of contraceptive glycodelin-A in the uterus during periovulatory midcycle is consistent with an open "fertile window." Glycodelin induced by local or systemic administration of progestogens may potentially reduce the fertilizing capacity of sperm in any phase of the menstrual cycle. Glycodelin also has immunosuppressive activity. Its high concentration at the fetomaternal interface may contribute to protection of the embryonic semiallograft. Besides being an epithelial differentiation marker, glycodelin appears to play a role in glandular morphogenesis, as transfection of glycodelin cDNA into a glycodelin-negative breast cancer cells resulted in formation of gland-like structures, restricted proliferation, and induction of other epithelial markers. These various properties, as well as the chemistry, biology, and clinical aspects of glycodelin, continue to be areas of active investigation reviewed in this communication.