Human embryo implantation: current knowledge and clinical implications in assisted reproductive technology

Feasible Influence of G-CSF on Clinical Pregnancy Outcome in Oocyte Donation Cycles for Patients with Recurrent Implantation Failure

Background and Objectives: The aim of our single-center cohort study was the determination of the influence of the intrauterine lavage of granulocyte colony-stimulating growth factor (G-CSF) on clinical pregnancy rate in patients with a history of implantation failure older than 40 years. Materials and Methods: The study was conducted in Ferticare Prague SE between May 2018 and June 2020. Overall, 115 patients were distributed into two arms, with 48 subjects in the experimental and 67 in the control arm. All women have had a previous history of unsuccessful history of infertility treatment with their own genetic material and at least one ineffective cycle with the donated oocytes. The experimental arm underwent the intrauterine lavage of 0.5 mL of pure G-CSF from 120 to 48 h prior to embryo transfer. Results: The clinical pregnancy rate was 63.3% in the experimental arm and 47.8% in the control arm (p = 0.097 for Pearsonߣs χ2, and p = 0.133 for Fisher's exact test). However, the mean endometrial thickness on the day of embryo transfer did not appear to be statistically different (p = 0.139). Only the difference in endometrium thickness growth was statistically significant (p = 0.023). The increase in pregnancy rate is still encouraging for the future, even if it is not significant. Conclusion: Our study suggests the trend of increased pregnancy rate after the intrauterine G-CSF lavage in the interval of 120-48 h prior to embryo transfer.

Molecular regulators of human blastocyst development and hatching: Their significance in implantation and pregnancy outcome

In humans, blastocyst hatching and implantation events are two sequential, critically linked and rate-limiting events for a prospective pregnancy. These events are regulated by embryo-endometrium derived molecular factors which include hormones, growth factors, cytokines, immune-modulators, cell adhesion molecules and proteases. Due to poor viability of blastocysts, they fail to hatch and implant, leading to a low 'Live Birth Rates', majorly contributing to infertility. Here, embryo-derived biomarkers analysis plays a key role to assess potential biological viability of blastocysts which are capable of implantation and prospective pregnancy. Thus far, embryo-derived biomarkers examined are mostly immune-modulators which are thought to be associated with blastocyst development-implantation and progression of pregnancy, leading to live births. There is an urgent need to develop a quantitative and a reliable non-invasive approach aiding embryo selection for elective single embryo transfer and to minimize recurrent pregnancy loss and multiple pregnancies. In this article, we provide a comprehensive review on our current knowledge and understanding of potential embryo-derived molecular regulators, that is, biomarkers, of development of human blastocysts, their hatching and implantation. We discuss their potential implications in the assessment of blastocyst implantation potential and pregnancy outcome in terms of live births in humans.

Altered Molecular Pathways and Biomarkers of Endometrial Receptivity in Infertile Women with Polycystic Ovary Syndrome

Anovulation is the most prominent cause of infertility in polycystic ovary syndrome (PCOS) patients. Although ovulation can be corrected pharmacologically, the number of pregnancies remains low. Even if excellent embryos are transferred by IVF, it does not change the high miscarriage rate of PCOS patients. These facts collectively indicate that there is a disorder of endometrial development and receptivity to the embryo in PCOS patients, including the decrease of receptive ability, inhibition of embryo adhesion, undersupply of energy, poor blood perfusion, and pro-inflammatory status in the endometrium. However, it has never received the same attention as ovulatory dysfunction. Here we list some alternations of endometrial receptivity in women with PCOS, discuss the underlying intricate mechanisms, and try to find out the possible therapeutic targets, which may bring new perspectives to those who are able to provide high-quality embryos.

The outcomes of sequential embryo transfer in patients undergoing in vitro fertilization with frozen-thawed embryos: A retrospective study

AIM

To explore whether sequential embryo transfer benefits patients with repeated implantation failure (RIF) undergoing frozen-thawed embryo transfer (FET) cycles.

METHODS

We included 311 patients with a history of RIF in this retrospective study. We did sequential transfers with a cleavage embryo on day 3 and a blastocyst on day 5 in 77 patients; blastocyst transfers with two blastocysts on day 5 in 80 patients; and cleavage embryo transfers with two cleavage embryos on day 3 in 154 patients. We compared clinical outcomes between the three groups.

RESULTS

The clinical pregnancy rate was comparable between the blastocyst transfer group (48.8%), the sequential transfer group(48.1%) and the cleavage embryo transfer group (48.1%). There was no statistically significant difference found (p > 0.05). The ongoing pregnancy and multipregnancy rates were also comparable between the three groups (p > 0.05). The early miscarriage rate was significantly higher in the sequential transfer group (32.4%) compared with the blastocyst group (12.8%) and the cleavage embryo group (12.2%) (p < 0.05). However, after adjusting for confounders, there was no significant difference in early miscarriage rates in the sequential transfer group compared with the blastocyst group (odds ratio [OR], 2.97; 95% confidence interval [CI], 0.85-9.24; p = 0.07) and the cleavage embryo group (OR, 3.03; 95% CI, 0.94-8.06; p = 0.08).

CONCLUSIONS

Sequential embryo transfer failed to improve clinical outcomes for patients with RIF.

Comparison of Efficacy Between Vaginal Sildenafil and Granulocyte-Colony Stimulating Factor (G-CSF) in Improving Endometrial Thickness (ET) in Infertile Women

Background

Infertility is presently an emanating preventive medicine issue with some severe societal repercussions associated with it. In India, approximately a score percent of couples bear the burden of infertility. Moreover, the declining fertility rates despite effective artificial reproductive techniques and increasing development of modern reproductive medicine from the last two censuses pose an alarm to the demographic progression data. Many studies have highlighted the importance of shifting the research focus to endometrial receptivity for increasing clinical pregnancy. 

Objective 

This research aims to compare the efficacy of treatments of vaginal sildenafil citrate and granulocyte-colony stimulating factor (G-CSF) intrauterine injection in increasing endometrial thickness (ET).

Methodology 

This was a randomized control trial (RCT) conducted over a two months period. Women seeking infertility treatment were recruited from the hospital's gynecological outpatient department (OPD). After the subjects gave informed consent, their history, clinical examination, and investigations were assessed. From the sixth day of the menstrual cycle, group A and group B had serial trans-vaginal ultra-sonographic evaluations for baseline endometrial thickness measurements. From day six to day 12 of the menstrual cycle, patients of group A were requested to self-administer per vaginal sildenafil citrate 25 mg every six hours. ET was evaluated sonographically on day 12 and day 14 of their menstrual cycle. Patients of group B received G-CSF 300 mcg/ml as intrauterine instillation on day 10 and were evaluated sonographically on day 12 and day 14 of their menstrual cycle. Patients then underwent additional therapy in the form of intrauterine injection (IUI), intracytoplasmic sperm injection with/without embryo transfer (ICSI/ET), or a natural cycle. Paired as well as unpaired t-tests were applied to the study groups to detect significant differences in the measurement of endometrial thickness before and after treatment.

Results

It was noticed that both sildenafil and G-CSF are agents for increasing endometrial thickness. The mean increase in endometrial thickness in the sildenafil treated group was 3.87 mm, while the mean increase in endometrial thickness in G-CSF treated group was 3.27 mm.

Conclusion 

This study has evidence of better results in improving endometrial thickness in infertile women by using vaginal sildenafil with respect to endometrial growth with an intrauterine infusion of granulocyte colony-stimulating factor (filgrastim, G-CSF).

Serum and cervico-vaginal glycodelin concentrations as predictors of successful implantation after embryo transfer

OBJECTIVE

Evaluation of glycodelin (Gd) concentrations in serum and cervico-vaginal secretions as a predictor for implantation after ICSI.

MATERIALS AND METHODS

Prospective study on 50 women undergoing ICSI where long protocol ovarian stimulation was used. Serum and cervico-vaginal lavage Gd concentrations were measured then rates of biochemical and clinical pregnancy were detected and predictive value was evaluated using logistic regression analysis.

RESULTS

Using cut-off values of 2.2 ng/ml and 1.9 ng/ml for serum and cervico-vaginal Gd concentrations respectively for biochemical pregnancy and values of 2.7 ng/ml and 1.3 ng/ml respectively for clinical pregnancy, there was no significant difference regarding sensitivity (72% & 56%, and 72% & 89%, respectively and respectively). Specificity was statistically similar for biochemical pregnancy (72% and 89%, respectively) while specificity was significantly higher for clinical pregnancy using cervico-vaginal Gd concentration of 1.3 ng/ml (88%) compared to serum Gd concentration of 1.9 ng/ml (53%).

CONCLUSION

Glycodelin appears to be a promising marker for implantation after IVF/ICSI.

Interleukin 22 Expression During the Implantation Window in the Endometrium of Women with Unexplained Recurrent Pregnancy Loss and Unexplained Infertility Compared to Healthy Parturient Individuals

We evaluated the expression of interleukin-22 (IL-22) in the endometrium of women with unexplained recurrent pregnancy loss (uRPL) and unexplained infertility (UI) compared to the women with normal pregnancies. Endometrial tissues were collected from 20 women with UI, 20 women with uRPL, and 24 healthy women as a control group. Immunohistochemical expression and gene expression of IL-22 were analyzed by immunohistochemistry (IHC) and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) methods. The controls showed lower IL-22 expression than the uRPL group (P > 0.05) using PCR. It was also found that patients with UI had lower levels of IL-22 expression compared to the uRPL group (P > 0.05). Although IL-22 expression in the endometrium of patients with UI was higher than the control group, this difference was not statistically significant (P < 0.05). IL-22 immunoreactivity was observed in the endometrial glands and stromal tissues using IHC. We found the lowest IL-22 expression in the control group and the highest in uRPL samples (P < 0.05). Our findings suggest that a significant increase in IL-22 expression in uRPL patients may affect fertility and pregnancy outcomes or even have a considerable impact on immune function deficits. Further studies on the critical function of IL-22 during pregnancy are suggested.

A review of the pathophysiology of recurrent implantation failure

Implantation is a critical step in human reproduction. The success of this step is dependent on a competent blastocyst, receptive endometrium, and successful cross talk between the embryonic and maternal interfaces. Recurrent implantation failure is the lack of implantation after the transfer of several embryo transfers. As the success of in vitro fertilization has increased and failures have become more unacceptable for patients and providers, the literature on recurrent implantation failure has increased. While this clinical phenomenon is often encountered, there is not a universally agreed-on definition-something addressed in an earlier portion of this Views and Reviews. Implantation failure can result from several different factors. In this review, we discuss factors including the maternal immune system, genetics of the embryo and parents, anatomic factors, hematologic factors, reproductive tract microbiome, and endocrine milieu, which factors into embryo and endometrial synchrony. These potential causes are at various stages of research and not all have clear implications or immediately apparent treatment.

The Role of Transvaginal Ultrasound Guided Embryo Transfer to Improve Pregnancy Rate in Obese Patients Undergoing Intracytoplasmic Sperm Injection

Objective

To evaluate the effectiveness of transvaginal ultrasound (TVUS) versus the transabdominal ultrasound (TAUS) guided embryo transfer (ET) in obese patients undergoing Intracytoplasmic sperm injection (ICSI).

Design

A prospective randomized controlled trial.

Setting

University hospital.

Patient(s)

Eight hundred participants with BMI ≥30 received the long agonist protocol. They were randomized into 2 equal groups of 400 patients. Each group had either TAUS guided ET or TVUS guided ET.

Main Outcome Measure(s)

Our primary outcomes were clinical pregnancy rate, degree of patient pain assessed by visual analogue scale (VAS). The secondary outcomes were live birth rate, implantation rate, miscarriage and chemical pregnancy rates, duration of ET.

Result(s)

Our results showed a significant higher chemical and clinical pregnancy rates in the TVUS group in comparison to TAUS group (45.3% vs. 38.3%, p=0.045) and (37.8% vs. 30.8%, p=0.044) respectively. There was tendency for increased live birth rates in the TVUS group however it did not reach statistical significance (50.2% vs. 44.8%). The VAS of the pain was significantly less in TVUS group in comparison to the TAUS group (2.1 ±0.7 vs. 4.5 ±1.3), also abdominal discomfort was significantly less in TVUS group in comparison to the TAUS group (13% vs. 58%) p= value 0.0001.

Conclusion(s)

This study showed superior role of TVUS guided ET over TAUS regarding less pain and better pregnancy and live birth rates in obese participants.

Clinical Trial Registration Number

Clinical trial. Gov identifier NCT03473028.

Immunotherapy in endometrial cancer: rationale, practice and perspectives

Tumor immunotherapy has attracted more and more attention nowadays, and multiple clinical trials have confirmed its effect in a variety of solid tumors. Immune checkpoint inhibitors (ICIs), cancer vaccines, adoptive cell transfer (ACT), and lymphocyte-promoting cytokines are the main immunotherapy methods. Endometrial cancer (EC) is one of the most frequent tumors in women and the prognosis of recurrent or metastatic EC is poor. Since molecular classification has been applied to EC, immunotherapy for different EC subtypes (especially POLE and MSI-H) has gradually attracted attention. In this review, we focus on the expression and molecular basis of the main biomarkers in the immunotherapy of EC firstly, as well as their clinical application significance and limitations. Blocking tumor immune checkpoints is one of the most effective strategies for cancer treatment in recent years, and has now become the focus in the field of tumor research and treatment. We summarized clinical date of planned and ongoing clinical trials and introduced other common immunotherapy methods in EC, such as cancer vaccine and ACT. Hormone aberrations, metabolic syndrome (MetS) and p53 mutant and that affect the immunotherapy of endometrial cancer will also be discussed in this review.

Placental diseases associated with assisted reproductive technology

The placenta develops from the outer trophoblastic layer following the differentiation of the fertilized ovum and is therefore more susceptible to epigenetic regulatory changes caused by environmental interventions and influences during assisted reproductive technology. Furthermore, the placenta regulates the development of the fetal heart, brain, kidneys, bones, and other tissues and organs [1]. Placental dysplasia leads to poor perinatal outcomes as well as long-term health risks later in life, including neurodevelopmental disorders, tumors, and adult metabolic syndrome [2,3]. In view of the decisive role of the placenta during intrauterine fetal development, Graham J. Burton, an expert in placentology from the University of Cambridge, formally proposed the theory of "placenta-derived chronic diseases" in 2018 based on embryonic-derived diseases [4]. In this review, we summarized the changes in placental morphology and structure, growth dynamics, imprinted and non-imprinted genes, and other aspects attributable to assisted reproduction technology. Our review provides a theoretical basis for further research on placental changes caused by assisted reproductive technology that are most strongly associated with an increased risk of neonatal long-term diseases.

Retrospective study of placenta accreta, placenta increta and placenta percreta in Peripartum hysterectomy specimens

Background

Abnormal placentations such as placenta accreta, placenta increta and placenta percreta are important causes of hemorrhage after delivery causing maternal morbidity and mortality. Risk factors for abnormal placentation are prior caesarean section, placenta previa and pre-eclampsia. There is a need for reliable antenatal diagnosis for these serious conditions. If these pregnancies can be identified, antepartum, site and time of delivery as well as the surgical approach can be planned ahead; this decreases the incidence of maternal mortality due to massive hemorrhage.

Aim

(1) To study the incidence of abnormal placentation in emergency peripartum hysterectomy specimen. (2) To evaluate various risk factors associated with abnormal placentation.

Materials and Method

Retrospective cross-section study done in patients with abnormal placentation leading to emergency peripartum hysterectomy during a course of eight-year period.

Result

We received total of 18 emergency hysterectomy specimens during eight-year period of which placenta accreta accounts 55.5 percent (10/18), placenta increta upto 38.8 percent (7/18) and placenta percreta 5.5 percent (1/18). Analysis of result with parity shows uniparous women up to 22.2 percent (4/18), and multiparous women 77.7 percent (14/18). Risk factor analysis shows previous caesarean section in 55.5 percent (10/18), placenta previa in 33.3 percent (6/18) and pre-eclampsia in 11.1 percent (2/18).

Conclusion

In our study, among abnormal placentation, incidence of placenta accreta accounts for 55.5 percent and it is more common in multiparous women than uniparous women. Among risk factors in our study, previous caesarean section is commonly associated with abnormal placentation followed by a placenta previa and pre-eclampsia.

A Retrospective Study of Placenta Accreta, Percreta, and Increta in Peripartum Hysterectomies in a Tertiary Care Institute in Northeast India

Background: Abnormal placentation such as placenta accreta, increta, and percreta are frequent causes of post-partum hemorrhage, which results in maternal morbidity and mortality. A previous history of cesarean section, placenta previa, and pre-eclampsia are the important risk factors for abnormal placentation. A reliable antenatal diagnosis and planned surgical approach can reduce the incidence of maternal morbidity and mortality from massive hemorrhage.

Aim: To study the incidence of abnormal placentation and the association of various risk factors with abnormal placentation.

Material and methods: A retrospective study over a period of eight years in patients with peripartum hysterectomies due to abnormal placentation presenting with massive hemorrhage.

Results: We received a total of 10 emergency hysterectomy specimens during an eight‑year period. Of the cases, placenta accreta accounted for 40% (4/10), increta up to 40% (4/10), and percreta 20% (2/10). Analysis of these findings with parity showed 20% of the women were uniparous (2/10), and 80% were multiparous (8/10). Risk factor analysis showed previous cesarean sections in 40% (4/10), placenta previa in 50% (5/10), and pre‑eclampsia in 10% (1/10).

Conclusion: The present study highlights the incidence of abnormal placentation in a tertiary care institute in Northeast India. Placenta accreta and increta constituted the major forms of abnormal placentation. Multiparous women with placenta previa followed by previous lower segment cesarean section were more at risk of having abnormal placentation. These findings will guide in antenatal care by risk prioritization and management planning of these patients.

A live birth with unexpectedly low serum human chorionic gonadotropin level on day 11 after blastocyst embryo transfer: a case report

Objective

To report a very rare case of live birth with unexpectedly low serum hCG level on day 11 after blastocyst embryo transfer.

Design

Case report.

Setting

Private infertility center.

Patients

A 30-year-old nulliparous woman presented with PCOS and 1 year of infertility.

Interventionss

Conventional IVF was scheduled and a long-acting agonist protocol was selected.

Main Outcome Measures

Maternal serum hCG levels and transvaginal ultrasound exams for the embryo's well-being.

Results

The hCG level was 11.6 IU/L on day 11 after the transfer of two blastocyst embryos, which was considered as either failing or extrauterine pregnancy. After blood titration, there were delayed hCG increases. A series of transvaginal ultrasounds also indicated a delayed but normal-appearing intrauterine pregnancy. A healthy baby boy was delivered at term by means of cesarean section.

Conclusions

A low initial serum hCG level may be associated with certain maternal or fetal characteristics and IVF treatment variables. Close conservative observation is warranted before undertaking any therapeutic intervention.

The ART of frozen embryo transfer: back to nature!

The implementation of cryopreservation-techniques in the IVF laboratory and the improved survival rates of oocytes, cleavage and blastocyst stage embryos have led to a significant increase in the number of frozen-thawed embryo transfer cycles (FET). FETs can be planned either in a 'pure' natural cycle, a modified natural cycle, a stimulated cycle or a hormonal replacement therapy cycle and the optimal means to prepare the endometrium for frozen embryo transfer is a topic of ongoing controversy. Recent findings report an increased risk of hypertensive disorders if pregnancy is achieved in a frozen embryo transfer cycle without an existing corpus luteum. Therefore, the question of how to prepare the endometrium has gained even more importance and taken on a new dimension as it should not simply be reduced to the basic question of 'which approach will result in superior pregnancy rates?' but instead 'which approach will result in the best pregnancy rates and the safest outcome for mother and baby?'. The aim of this review is to summarize and critically appraise the existing data on the different approaches of endometrial preparation for frozen embryo transfer with a special focus on the 'pure' natural cycle.

Levonorgestrel IUD: is there a long-lasting effect on return to fertility?

Intrauterine devices (IUDs) are effective and safe long-acting reversible contraceptive methods for preventing unplanned pregnancies. While extensive studies were conducted to evaluate return to fertility after removal of IUDs, majority of them were focused on multiparous women using copper IUDs. Current trends indicate increased use of levonorgestrel (LNG) IUDs in nulliparous women for very long periods of time, with both nulliparity and long duration of LNG-IUD use being potentially associated with trends towards longer time to conception post removal. Understanding the effects that LNG-IUDs may have on endometrial morphology and gene expression has important implications to further understanding their mechanism of action. Studies examining endometrial gene expression show persistent changes in receptivity markers up to 1 year after removal of an inert IUD, and no similar studies have been performed after removal of LNG-IUDs. Given the current gap in the literature and trends in LNG-IUD use in nulliparous young women, studies are needed that specifically look at the interaction of nulliparity, long-term use of LNG-IUD, and return to normal fertility. Herein, we review the available literature on the mechanism of action of IUDs with a specific focus on the effect on endometrial gene expression profile changes associated with IUDs.

Embryo transfer associated with hormone replacement therapy cycles using assisted reproductive technology increases placenta accreta spectrum

AIM

To evaluate obstetric outcomes in embryo transfer (ET) during estrogen with progestin hormone replacement therapy (HRT) cycles using assisted reproductive technology (ART).

METHODS

Of the 118 singleton pregnancies conceived with ART and delivered between January 2015 and December 2017, we reviewed the data of 87 cases that had information on HRT at the time of ET. Data on pregnancy outcomes included the presence of small for gestational age fetuses, hypertensive disorders of pregnancy, placenta previa (including low-lying placenta), placental abruption and placenta accreta spectrum (including placenta accreta, placenta increta and placenta percreta). We investigated the relationship between HRT cycles and adverse placental outcomes (placenta accreta spectrum, placental abruption, placenta previa, hypertensive disorders of pregnancy and small for gestational age fetuses). We then analyzed the associations that correlated with adverse placental outcomes.

RESULTS

Patients with ET during HRT cycles were more likely to have placenta accreta spectrum. During the study period, 87 out of 118 singleton live births using ART had information on HRT (60 HRT cycles and 27 ovulation cycles). The incidence of placenta accreta spectrum was significantly higher in the HRT cycle group than in the ovulation cycle group (HRT cycle, 31.7% [19 of 60] vs ovulation cycle, 7.4% [2 of 27]; P < 0.01).

CONCLUSION

The obstetric outcomes occurring in pregnancies involving HRT use may differ among ET cycles. ET during HRT cycles were associated with adverse obstetric outcomes due to placenta accreta spectrum. The potential interaction between HRT cycles and adverse placental events is novel and warrants further investigation.

Effect of GnRH agonist and letrozole treatment in women with recurrent implantation failure

OBJECTIVE

To compare the influence of dual suppression with the use of GnRH agonist plus aromatase inhibitor compared with suppression with the use of GnRH agonist alone or no suppression at all in patients with idiopathic recurrent implantation failure (RIF).

DESIGN

Retrospective cohort study.

SETTING

University-affiliated reproductive center.

PATIENT(S)

A total of 523 infertile women who failed two blastocyst transfers underwent a third frozen blastocyst transfer. Women with known endometriosis were excluded.

INTERVENTION(S)

A total of 204 subjects were not pretreated, 143 received 2 months of GnRH agonist (3.75 mg intramuscular leuprolide acetate monthly) only, and 176 received GnRH agonist and aromatase inhibitor (5 mg oral letrozole daily for 60 days). Demographic and stimulation information was collected and cycle outcomes reported.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy rates.

RESULT(S)

Age, antral follicle count, basal FSH levels, duration of infertility, previous pregnancies, and full-term deliveries were similar (P>.05). Clinical pregnancy rates were higher among women who received GnRH agonist plus letrozole compared with women who received GnRH agonist only or women without pretreatment (63%, 42%, and 40%, respectively; P<.0001). Live birth rates were higher among women who received GnRH agonist plus letrozole compared with the other groups (56%, 36%, and 34%; P<.0001). No differences in pregnancy outcomes were noted between patients who did not receive pretreatment and those in the GnRH agonist only group.

CONCLUSION(S)

In patients with RIF, treatment with a GnRH agonist plus letrozole may improve live birth rates in subsequent cycles. We hypothesize that this improvement is due to alterations in the endometrium receptivity or treatment of undiagnosed endometriosis.

Genetic variants linked to folliculogenesis and successful pregnancy are not associated with twin births in a twins' town

Background: Cândido Godói (CG) is a small city in South Brazil in which natural twin births (both monozygotic and dizygotic) occur at an unusually high rate and the twin trait runs through the local families, which are mostly European descendants. We have argued that a genetic founder effect must have occurred during the settlement of CG and that genetic factors may help to explain the familial aggregation of twinning in that city.Objective: The aim of this study was to evaluate single nucleotide polymorphisms (SNPs) related to folliculogenesis (rs6166:C > T in FSHR, rs11031006:G > A near FSHB, and rs17293443:T > C in SMAD3) and successful pregnancies (rs2010963:C > G in VEGFA, rs1800629:G > A in TNF, rs1801131:T > G and rs1801133:G > A in MTHFR) in mothers from CG.Study design: Forty-four mothers of twins (the case group) and 102 mothers of singletons (the control group) from CG were investigated. Genotypes were determined using real-time PCR (TaqMan^® SNP Genotyping Assay).Results: For all SNPs, the distributions of the genotypic and allelic frequencies were similar between cases and controls. Interestingly, a deviation from the Hardy-Weinberg equilibrium was detected for SNP rs11031006:G > A near FSHB in the control population. Different combinations of risk alleles and haplotypic analyses were homogeneously distributed between cases and controls.Conclusion: These results suggest a lack of association between the seven studied SNPs and twin births in CG. However, we hypothesized that other genetic variants related to folliculogenesis or successful pregnancies may be involved in this phenomenon. Identifying such genetic components may be important not only for the Brazilian "Twins' Town" but also for a better understanding of twinning in general.

Endometrial scratching for infertile women undergoing a first embryo transfer: a systematic review and meta-analysis of published and unpublished data from randomized controlled trials

OBJECTIVE

To investigate endometrial scratch injury (ESI) as an intervention to improve IVF outcome in women undergoing a first ET.

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENT(S)

Infertile women undergoing a first fresh/frozen embryo transfer.

INTERVENTION(S)

We included published and unpublished data from randomized controlled trials in which the intervention group received ESI and controls received placebo or no intervention. Pooled results were expressed as relative risk (RR) with 95% confidence interval (CI). The review protocol was registered in PROSPERO to start the data extraction (CRD42018087786).

MAIN OUTCOME MEASURE(S)

Ongoing pregnancy/live birth rate (OPR/LBR), clinical pregnancy rate (CPR), multiple pregnancy rate (MPR), miscarriage rate (MR), and ectopic pregnancy rate (EPR).

RESULT(S)

Seven studies were included (1,354 participants). We found a nonsignificant difference between groups in terms of OPR/LBR, CPR, MR, MPR, and EPR. Subgroup analysis found that ESI on the day of oocyte retrieval (achieved by a Novak curette) reduced OPR/LBR (RR 0.31, 95% CI 0.14-0.69) and CPR (RR 0.36, 95% CI 0.18-0.71), whereas ESI during the cycle preceding ET (performed through soft devices) had no effect on OPR/LBR and CPR. No difference in the impact of ESI was observed between fresh and frozen embryo transfer.

CONCLUSION(S)

Current evidence does not support performing ESI with the purpose of improving the success of a first ET attempt.

Accuracy and efficacy of embryo transfer based on the previous measurement of cervical length and total uterine length

PURPOSE

Aim of the study was to examine the accuracy of embryo transfer based on the previous measurement of cervical length and total uterine length.

METHODS

The study has taken place in an academic-assisted reproduction clinic. 248 patients with infertility requiring IVF/ICSI treatment have been included. All patients underwent IVF/ICSI cycles with antagonist protocol and were treated with controlled ovarian stimulation using recombinant FSH (100-400 IU/day). On the day of oocyte retrieval, all patients were given vaginally natural micronized progesterone in a dose of 200 mg/tds. All patients had transvaginal ultrasound measurement of cervical length and endometrial cavity length prior to embryo transfer and measurement of embryo distance (intrauterine air bubbles) from fundal surface of uterine cavity and internal cervical os immediately after embryo transfer. Embryo transfer was performed on days 2-3. Primary outcome was to estimate the accuracy of embryo transfer based on the measurement of the embryo distance from middle of uterine cavity after embryo transfer and secondary outcome was to assess the effect of embryo distance from uterine fundus and internal cervical os to clinical pregnancy rate.

RESULTS

The clinical pregnancy rate was 42.7%. The mean embryo distance from the middle of endometrial cavity was 0.48 ± 0.02 cm, the mean embryo distance from the uterine fundus was 0.88 ± 0.32 cm, and from the internal cervical os was 1.67 ± 0.45 cm. Multiple regression analysis showed that the embryo distance from middle of cavity was related to endometrial cavity length and to the embryo distance from the fundus and it was not related to Cx length, total uterine length, embryo distance from internal Cx os, and embryo transfer length.

CONCLUSIONS

Embryo transfer with the previous measurement of total uterine length and estimation of embryo transfer length can be performed with very good accuracy by a single operator.

Are intracytoplasmic sperm injection and high serum estradiol compounding risk factors for adverse obstetric outcomes in assisted reproductive technology?

OBJECTIVE

To evaluate whether intracytoplasmic sperm injection (ICSI) use and E2 on the final day of assisted reproductive technology (ART) stimulation are associated with adverse obstetric complications related to placentation.

DESIGN

Retrospective cohort study.

SETTING

Large private ART practice.

PATIENT(S)

A total of 383 women who underwent ART resulting in a singleton live birth.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Adverse placental outcomes composed of placenta accreta, placental abruption, placenta previa, intrauterine growth restriction, preeclampsia, gestational hypertension, and small for gestational age infants.

RESULT(S)

Patients with adverse placental outcomes had higher peak serum E2 levels and were three times more likely to have used ICSI. Adverse placental outcomes were associated with increasing E2 (odds ratio 1.36, 95% confidence interval 1.13-1.65) and ICSI (odds ratio 3.86, 95% confidence interval 1.61-9.27). Adverse outcomes increased when E2 was >3,000 pg/mL and continued to increase in a linear fashion until E2 was >5,000 pg/mL. The association of ICSI with adverse outcomes was independent of male factor infertility. Interaction testing suggested the adverse effect of E2 was primarily seen in ICSI cycles, but not in conventional IVF cycles. Estradiol >5,000 pg/mL was associated with adverse placental events in 36% of all ART cycles and 52% of ICSI cycles.

CONCLUSION(S)

ICSI and elevated E2 on the day of hCG trigger were associated with adverse obstetric outcomes related to placentation. The finding of a potential interaction of E2 and ICSI with adverse placental events is novel and warrants further investigation.

Uterine and arcuate arteries blood flow for predicting of ongoing pregnancy in in vitro fertilization

BACKGROUND

In this study, we aimed to investigate the ability of transvaginal Doppler ultrasonography in predicting in vitro fertilization (IVF) outcome in women undergoing this procedure.

MATERIALS AND METHODS

In this prospective observational study, 65 infertile women underwent IVF procedure in Isfahan, during 2013-2014, were studied. The pulsatility index (PI), resistive index (RI) and peak systolic velocity (PSV) of the uterine arteries and arcuate arteries were measured in all selected women using transvaginal color and pulsed Doppler measurements on the day of human chorionic gonadotrophin injection. The women followed up for the primary endpoint which was a successful pregnancy. The mean of PI, RI, and PSV were compared in groups of women who had successful IVF and not. The receiver operating characteristic (ROC) curve was used to determine the predictive value of studied indices.

RESULTS

In this study, from 65 women, 32 (49.2%) and 33 (50.8%) have successful and unsuccessful IVF outcome, respectively. The mean of PI and RI of both uterine and arcuate arteries were significantly lower in pregnant women than non-pregnant ones (P < 0.001). The area under the ROC curve of PI (84.7%) and RI (84.4%) for uterine arteries was higher than other indices. The most accurate indices for predicting the outcome of IVF was RI of uterine arteries with an accuracy of 81.5%.

CONCLUSION

The findings of this study indicated that PI and RI assessments of uterine arteries could be used as a routine non-invasive factor, before hCG stimulation, for predicting the outcome of IVF.

Role of inflammatory mediators in patients with recurrent pregnancy loss

OBJECTIVE

To examine interleukin-12 (IL-12), IL-18, IFN-γ, intracellular adhesion molecule-1 (ICAM-1), leukemia inhibitory factor (LIF), and migration inhibitory factor (MIF) levels in precisely-timed blood and endometrial tissue samples from women with idiopathic recurrent pregnancy loss (RPL).

DESIGN

Case-control study.

SETTING

University hospital.

PATIENT(S)

Twenty-one women with RPL and 20 women with proven fertility (controls).

INTERVENTION(S)

Primary endometrial cells and blood samples during the midsecretory phase (days 19-23).

MAIN OUTCOME MEASURE(S)

Detection of IL-12, IL-18, IFN-γ, ICAM-1, LIF, and MIF via enzyme-linked immunosorbent assay in both blood and endometrial tissue samples.

RESULT(S)

The blood and tissue levels of IL-12, IL-18, and IFN-γ were statistically significantly higher, and the blood and tissue levels of LIF and MIF were statistically significantly lower in patients with RPL. Only the level of tissue ICAM-1 was higher in patients with RPL. There was a strong correlation between blood and tissue level measurements of IL-12, IL-18, LIF, and MIF.

CONCLUSION(S)

Our findings support the hypothesis that inflammatory processes may contribute to pregnancy loss, possibly through their role in implantation. We found that blood and tissue levels of IL-18, LIF, and MIF, and tissue levels of IL-12, IFN-γ, and ICAM-1 have statistically significant prognostic relevance.

Human malignant melanoma-derived progestagen-associated endometrial protein immunosuppresses T lymphocytes in vitro

Progestagen-associated endometrial protein (PAEP) is a glycoprotein of the lipocalin family that acts as a negative regulator of T cell receptor-mediated activation. However, the function of tumor-derived PAEP on the human immune system in the tumor microenvironment is unknown. PAEP is highly expressed in intermediate and thick primary melanomas (Breslow’s 2.5mm or greater) and metastatic melanomas, correlating with its expression in daughter cell lines established in vitro. The current study investigates the role of melanoma cell-secreted PAEP protein in regulating T cell function. Upon the enrichment of CD3⁺, CD4⁺ and CD8⁺ T cells from human peripheral blood mononuclear cells, each subset was then mixed with either melanoma-derived PAEP protein or PAEP-poor supernatant of gene-silenced tumor cells. IL-2 and IFN-γ secretion of CD4⁺ T cells significantly decreased with the addition of PAEP-rich supernatant. And the addition of PAEP-positive cell supernatant to activated lymphocytes significantly inhibited lymphocyte proliferation and cytotoxic T cell activity, while increasing lymphocyte apoptosis. Our result suggests that melanoma cell-secreted PAEP protein immunosuppresses the activation, proliferation and cytotoxicity of T lymphocytes, which might partially explain the mechanism of immune tolerance induced by melanoma cells within the tumor microenvironment.

Bu Shen Huo Xue decoction restores endometrial leukemia-inhibitory factor but not Angiopoietin-2 expression, and improves uterine receptivity in the controlled ovarian stimulation rat model

Leukemia-inhibitory factor (LIF) and Angiopoietin-2 (Ang-2) are important factors in fertility. In the present study, it was investigated whether Bu Shen Huo Xue Decoction (BSHXD) prevents controlled ovarian hyperstimulation (COH) treatment-induced changes in endometrial LIF and Ang-2 expression and whether it has an effect on the number of implantation sites and live births in rats. Uteri were collected on day (D) 3, 4 and 5 of pregnancy, and LIF and Ang-2 protein and mRNA expression were detected using western blot analysis and quantitative polymerase chain reaction. On pregnancy D10, the average number of implantation sites was observed. The number of live births from each group was recorded. The results indicated that BSHXD treatment markedly increased the number of live births by restoring endometrial LIF expression and the implantation capacity in the COH rat model. In addition, no association was identified between LIF and Ang-2 expression. Therefore, this suggests that BSHXD may be useful for female reproduction.

The physiologic and therapeutic role of heparin in implantation and placentation

Implantation, trophoblast development and placentation are crucial processes in the establishment and development of normal pregnancy. Abnormalities of these processes can lead to pregnancy complications known as the great obstetrical syndromes: preeclampsia, intrauterine growth restriction, fetal demise, premature prelabor rupture of membranes, preterm labor, and recurrent pregnancy loss. There is mounting evidence regarding the physiological and therapeutic role of heparins in the establishment of normal gestation and as a modality for treatment and prevention of pregnancy complications. In this review, we will summarize the properties and the physiological contributions of heparins to the success of implantation, placentation and normal pregnancy.

VEGF Splicing and the Role of VEGF Splice Variants: From Physiological-Pathological Conditions to Specific Pre-mRNA Splicing

During this past decade, the vascular endothelial growth factor (VEGF) pathway has been extensively studied. VEGF is a paradigm of molecular regulation since its expression is controlled at all possible steps including transcription, mRNA stability, translation, and pre-mRNA splicing. The latter form of molecular regulation is probably the least studied. This field has been neglected; yet different forms of VEGF with different sizes and different physiological properties issued from alternative splicing have been described a long time ago. Recently a new level of complexity was added to the field of splicing of VEGF pre-mRNA. Whereas thousands of publications have described VEGF as a pro-angiogenic factor, an alternative splicing event generates specific anti-angiogenic forms of VEGF that only differ from the others by a modification in the last six amino acids of the protein. According to the scientists who discovered these isoforms, which are indistinguishable from the pro-angiogenic ones with pan VEGF antibodies, some of the literature on VEGF is at least inexact if not completely false. Moreover, the presence of anti-angiogenic forms of VEGF may explain the disappointing efficacy of anti-VEGF therapies on the overall survival of patients with different forms of cancers and with wet age-related macular degeneration. This review focuses on the existence of the different alternative splice variants of VEGF and the molecular mechanisms associated with their expression and function.

Reduced uterine receptivity for mouse embryos developed from in-vitro matured oocytes

PURPOSE

The outcomes of in-vitro maturation (IVM) are inferior compared to those of IVF. The purpose of the study was to compare the implantation rates of IVM- and in-vivo maturation (IVO)- derived embryos, and to evaluate their effects on uterine receptivity.

METHODS

The IVM- and IVO- oocytes were obtained from female mice, fertilized and transferred to separate oviducts of the same pseudo-pregnant mice. After 5 days, the implanted blastocysts were dissected out of the uterine horns, and the uterine horns were analyzed for the expression of mRNAs encoding leukemia inhibitory factor, heparin-binding epidermal growth factor, insulin-like growth factor binding protein-4, progesterone receptor, and Hoxa-10.

RESULTS

The maturation rate of the IVM- oocytes was 81.2%. The fertilization rate of the IVM oocytes was lower than that of the IVO oocytes (50.5% vs. 78.0%, p = 0.038), as was their implantation rate (14.5% vs. 74.7%, p < 0.001). All 5 mRNAs examined were expressed at significantly lower levels in the uterine horns that received the IVM-derived embryos than in those that received the IVO-derived embryos.

CONCLUSIONS

The IVM-derived embryos are less competent in inducing expression of implantation-related mRNAs in the uterine horn.

Endometrial receptivity markers in infertile women stimulated with letrozole compared with clomiphene citrate and natural cycles

Though various advantages associated with the use of letrozole as an ovulation inducing drug are documented, there is inadequate information regarding its effect on endometrial receptivity. Expression of endometrial receptivity markers including αvβ3 integrin, L-selectin, LIF, and pinopods during the implantation window in infertile women stimulated with letrozole or clomiphene citrate (CC), and spontaneous cycles is investigated. A total of 36 women were included in the study out of which 16 women were diagnosed with primary unexplained infertility and the other 20 women with severe oligoasthenozoospermic/azoospermic male partners. Both groups were sub-divided into three groups; women stimulated with letrozole, or with CC, and the third group was allowed to ovulate spontaneously (natural cycles). Women having natural cycles and not given any drug were considered as controls. Once ovulation was confirmed by ultrasonography, endometrial samples were collected on the seventh day post-ovulation and analyzed. In women with unexplained infertility treated with letrozole and CC, epithelial and stromal expression of αvβ3 integrin, L-selectin, leukemia inhibitory factor (LIF), and pinopod formation was found to be significantly higher as compared to controls. Expression of these receptivity markers was found to be comparable amongst the letrozole, CC, and control groups in women with severe oligoasthenozoospermic/azoospermic male partners. Cell cycle analysis showed similar cell cycle phase fractions on comparing the CC and the letrozole groups. Stimulation with letrozole and CC appears to enhance endometrial receptivity in women with unexplained infertility. However, letrozole and CC did not have any significant effect on the endometrial receptivity markers of women with severe oligoasthenozoospermic/azoospermic male partners.

Differential expression of serum glycodelin and insulin-like growth factor binding protein 1 in early pregnancy

This prospective study evaluated whether serum glycodelin and insulin-like growth factor binding protein 1 (IGFBP-1) predict the likelihood of embryo implantation in recipients undergoing donor egg in vitro fertilization. We measured glycodelin and IGFBP-1 at 6 points from lining check to lutenizing hormone (LH) + 31. β-Human chorionic gonadotropin levels were first measured at LH + 17. The recipients were divided into those without embryo implantation (group 1, n = 6) and those with successful implantation (group 2, n = 30). Although this is a negative study in that neither glycodelin nor IGFBP-1 alone reflected endometrial (EM) receptivity, the glycodelin/IGFBP-1 ratio on the day of blastocyst transfer was higher in recipients who achieved pregnancy (P = .05). At LH + 17, glycodelin was higher (P = .04), and IGFBP-1 was lower (P = .004) in recipients who achieved pregnancy when compared to those who did not. These observations are likely due to EM changes induced by successful embryo implantation.

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.

Comparative transcriptome analysis of human trophectoderm and embryonic stem cell-derived trophoblasts reveal key participants in early implantation

The implantation process begins with attachment of the trophectoderm (TE) of the blastocyst to the maternal endometrial epithelium. Herein we have investigated the transcriptome of mural TE cells from 13 human blastocysts and compared these with those of human embryonic stem cell (hESC)-derived-TE (hESC(troph)). The transcriptomes of hESC(troph) at Days 8, 10, and 12 had the greatest consistency with TE. Among genes coding for secreted proteins of the TE of human blastocysts and of hESC(troph) are several molecules known to be involved in the implantation process, as well as novel ones, such as CXCL12, HBEGF, inhibin A, DKK3, WNT5A, and follistatin. The similarities between the two lineages underscore some of the known mechanisms and offer discovery of new mechanisms and players in the process of the very early stages of human implantation. We propose that the hESC(troph) is a viable functional model of human trophoblasts to study trophoblast-endometrial interactions. Furthermore, the data derived herein offer the promise of novel diagnostics and therapeutics aimed at practical challenges in human infertility and pregnancy disorders associated with abnormal embryonic implantation.

Extracts from a traditional Chinese herbal remedy (Zhuyun recipe) improve endometrial receptivity in mice with embryonic implantation dysfunction and ovulation stimulation

OBJECTIVE

Although ovarian stimulation has an important role in assisted reproductive technologies (ART), it may also have detrimental effects on endometrial receptivity. Traditional Chinese herbal remedy, as a kind of traditional treatments, has been widely and increasingly applied in clinic. In this article, the impact of traditional Chinese medicines (TCM) on embryonic implantation, pregnant rate and underlying mechanisms will be investigated.

METHODS

One hundred and sixty-three female pregnant kunming mice were randomly divided into 6 groups, including A, control group; B, ovulation stimulation (OS) group; C, OS+TCM group; D, embryo implantation dysfunction (EID) group; E, EID+TCM group; F, TCM only group. Uterus samples were collected at gestation Day 4 and were detected with immunohistochemistry and Real Time-PCR analyses. Uterine horns were excised to determine the number of pregnant mice and implantation sites on the Day 8 postcoitum.

RESULTS

OS group and EID group showed a significant decrease in pregnant rate and the expression of both the endometrial leukaemia inhibitory factor (LIF) and integrin β3 subunit during the implantation window. OS+TCM group and EID+TCM group showed a higher pregnant rate and endometrial LIF and integrin β3 subunit expression compared to OS group and EID group. The number of implanted embryo in EID group was lower than in control group, but higher in EID+TCM group than in EID group. No significant difference was found in the measured indices between the TCM only group and control group.

CONCLUSIONS

OS model and EID model may have a negative influence on endometrial receptivity and embryonic implantation in mice. Conversely, TCM appears to reverse the expression of endometrial LIF and integrin β3 subunit, improves the uterine receptivity in mice and increases pregnant rate and embryonic implantation. It provides a new insight into the clinic infertility's treatment.

MicroRNA array and microarray evaluation of endometrial receptivity in patients with high serum progesterone levels on the day of hCG administration

BACKGROUND

To determine the effect of higher progesterone (P) level on endometrial receptivity.

METHODS

This was a prospective analysis conducted in the Reproductive Medical Center of Peking University Third Hospital. All patients received IVF treatment and canceled embryo transfer in the same cycle and were divided into group 1 (normal P; 7 patients) and group 2 (elevated P; 12 patients). Endometrial biopsies were performed 6 days after oocyte retrieval. The global miRNA and mRNA gene expressions in endometrial biopsies were investigated with a V4.0 miRNA probe and 22 K Human Genome Array. Fold ratios were derived to compare gene regulation between the groups. Spp1 and Ang gene expression was selected to verify the array results by RT-PCR and the protein expression of osteopontin and VEGF was determined using an immunohistochemical method.

RESULTS

There were 4 miRNA (all down-regulated) and 22 mRNA (13 up-regulated and 9 down-regulated) exhibiting differential expression between the groups on the microRNA and microarray chips. miRNA-451, Spp1, and Ang expression in RT-PCR verified the array results. Osteopontin and VEGF were also shown to have positive expression in the endometrium.

CONCLUSIONS

Data from microRNA and microarray analysis suggests dissimilar endometrial receptivity in patients with high P levels on the day of hCG, and elevated osteopontin and decreased VEGF had poor pregnancy rates.

Expression of endometrial protein markers in infertile women and the association with subsequent in vitro fertilization outcome

Endometrial biopsies were performed during the luteal phase just before an IVF cycle in 104 infertile women, and immunohistochemical staining was performed to investigate expression patterns of hCG-LH receptor, leukemia-inhibitory factor, macrophage colony-stimulating factor, HOXA-10, vascular endothelial growth factor A, and their relation to subsequent IVF pregnancy. Only glandular expression of vascular endothelial growth factor A in early luteal endometrium was significantly higher in the pregnant group compared with the nonpregnant group (6.0 ± 3.9 vs. 2.9 ± 3.4) and thus could be a predicting marker for subsequent IVF pregnancy.

Bioinformatic detection of E47, E2F1 and SREBP1 transcription factors as potential regulators of genes associated to acquisition of endometrial receptivity

BACKGROUND

The endometrium is a dynamic tissue whose changes are driven by the ovarian steroidal hormones. Its main function is to provide an adequate substrate for embryo implantation. Using microarray technology, several reports have provided the gene expression patterns of human endometrial tissue during the window of implantation. However it is required that biological connections be made across these genomic datasets to take full advantage of them. The objective of this work was to perform a research synthesis of available gene expression profiles related to acquisition of endometrial receptivity for embryo implantation, in order to gain insights into its molecular basis and regulation.

METHODS

Gene expression datasets were intersected to determine a consensus endometrial receptivity transcript list (CERTL). For this cluster of genes we determined their functional annotations using available web-based databases. In addition, promoter sequences were analyzed to identify putative transcription factor binding sites using bioinformatics tools and determined over-represented features.

RESULTS

We found 40 up- and 21 down-regulated transcripts in the CERTL. Those more consistently increased were C4BPA, SPP1, APOD, CD55, CFD, CLDN4, DKK1, ID4, IL15 and MAP3K5 whereas the more consistently decreased were OLFM1, CCNB1, CRABP2, EDN3, FGFR1, MSX1 and MSX2. Functional annotation of CERTL showed it was enriched with transcripts related to the immune response, complement activation and cell cycle regulation. Promoter sequence analysis of genes revealed that DNA binding sites for E47, E2F1 and SREBP1 transcription factors were the most consistently over-represented and in both up- and down-regulated genes during the window of implantation.

CONCLUSIONS

Our research synthesis allowed organizing and mining high throughput data to explore endometrial receptivity and focus future research efforts on specific genes and pathways. The discovery of possible new transcription factors orchestrating the CERTL opens new alternatives for understanding gene expression regulation in uterine function.