Recurrent implantation failure: gamete and embryo factors

New Insight of Lipiodol Flush on Pregnancy Outcomes in Women with Recurrent Implantation Failure Undergoing IVF/ICSI: a Prospective Study Based on Propensity Score Matching

Pregnancy outcomes in women with recurrent implantation failure (RIF) undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI): does treatment with lipiodol flush matter? In this propensity score-matched study, we recruited 966 RIF patients who underwent IVF/ICSI from two tertiary hospitals. These patients were divided into groups based on whether they received lipiodol flush or not. Further stratification was applied to investigate the effect of lipiodol flush on pregnancy outcomes in RIF patients with different cycle type of embryo transferred. Then, patients subjected to lipiodol flush were categorized into three groups based on the duration of the interval: short interval (≤ 3 months), moderate interval (3-6 months), and long interval (≥ 6 months). The groups were well-matched at baseline. The lipiodol flush group exhibited a significantly lower incidence of biochemical pregnancy (46.27% vs. 56.22%, p = 0.046) and live birth (25.87% vs. 37.31%, p = 0.014). Subgroup analysis for fresh embryo transfer cycles revealed no significant differences in pregnancy outcomes. Among RIF patients underwent frozen-thawed embryo transfer cycle, a statistically significant difference in the live birth rate was observed in the lipiodol flush group when compared to the control group (26.40% vs. 37.21%, p = 0.030). Analysis of different lipiodol flush intervals demonstrated a significantly lower live birth rate in the lipiodol flush group. Our results challenge the value of lipiodol use in clinical practice for the treatment of RIF.Trial registration: Chinese Clinical Trial Registry, ChiCTR1900024273. Registered 4 July 2019.

Meta-analysis of intrauterine hCG perfusion efficacy in recurrent implantation failure as defined by ESHRE guidelines

PURPOSE

This study evaluates the efficacy of intrauterine hCG perfusion for RIF, as defined by ESHRE 2023 guidelines, highlighting hCG as a cost-effective alternative to other immunotherapies, especially suitable for less developed regions. It aims to clarify treatment guidance amidst previous inconsistencies.

METHODS

This meta-analysis, registered with PROSPERO (CRD42024443241) and adhering to PRISMA guidelines, assessed the efficacy and safety of intrauterine hCG perfusion in enhancing implantation and pregnancy outcomes in RIF. Comprehensive literature searches were conducted through December 2023 in major databases including PubMed, Web of Science, Embase, the Cochrane Library, and key Chinese databases, without language restrictions. Inclusion and exclusion criteria were strictly aligned with the 2023 ESHRE recommendations, with exclusions for studies lacking robust control, clear outcomes, or adequate data integrity. The risk of bias was evaluated using the Newcastle-Ottawa Scale, ROBINS-I, and RoB2 tools. Data analysis was performed in R using the 'meta' package, employing both fixed and random effect models to account for study variability. Subgroup analyses by dosage, volume, hCG concentration, timing of administration, and type of embryo transfer were conducted to deepen insights, enhancing the reliability and depth of the meta-analysis in elucidating the role of hCG perfusion in RIF treatments.

RESULTS

Data from 13 studies, comprising six retrospective and six prospective studies from single centers, along with one multi-center RCT, totaling 2,157 participants, were synthesized to evaluate the effectiveness of intrauterine hCG perfusion in enhancing implantation and pregnancy outcomes in patients with RIF. Significant improvements were observed in clinical pregnancy and embryo implantation rates across various dosages, timing of administration, and embryo developmental stages, without impacting miscarriage rates. Notably, the most significant efficacy within subgroups occurred with a 500 IU dosage and perfusion parameters of ≤ 500µL volume and ≥ 2 IU/µL concentration. Additionally, a limited number of studies showed no significant increases in ectopic pregnancy or multiple pregnancy rates, and a modest improvement in live birth rates, although the small number of these studies precludes definitive conclusions.

CONCLUSIONS

The analysis suggests that intrauterine hCG perfusion probably enhances embryo implantation, clinical pregnancy, and live birth rates slightly in RIF patients. Benefits are indicated with a dosage of 500 IU and a maximum volume of 500µL at concentrations of at least 2 IU/µL. However, substantial heterogeneity from varying study types and the limited number of studies necessitate cautious interpretation. These findings underscore the need for more rigorously designed RCTs to definitively assess the efficacy and safety.

Exploring the effectiveness of endometrial receptivity array and immune profiling in patients with multiple implantation failure：A retrospective cohort study based on propensity score matching

This study aimed to evaluate the effectiveness of the endometrial receptivity array (ERA), endometrial immune profiling, and a combination of both in improving the pregnancy outcomes for multiple implantation failure patients. According to patients' willingness, 1429 women who incurred at least two or more consecutive implantation failures in IVF/ICSI treatment opted for frozen embryo transfer and were divided into four groups: 'No test', 'Immune Profiling', 'ERA' and 'ERA+ Immune Profiling'. Women in three test groups underwent timed endometrial biopsy for ERA, immune profiling, a combination of both. We observed the overall incidence rates of the displaced window of implantation (WOI) and endometrial immune dysregulation were 75.14% and 79.29%, respectively. After 1:1 propensity score matching (PSM), our data revealed that the 'ERA' and 'ERA + Immune Profiling' groups demonstrated significantly higher rates of biochemical, clinical, ongoing pregnancy, and implantation compared to the 'No test' group (p < 0.01). The 'Immune Profiling' group showed a higher implantation rate compared to 'No test' group (p < 0.05). Furthermore, when comparing three test groups, the 'ERA + Immune Profiling' group exhibited notably higher rates of clinical and ongoing pregnancy compared to the 'Immune Profiling' group (p < 0.017). However, there was no association between endometrial immune profiling and ERA phases, and their results did not differ between embryo implantation and non-implantation in these patients. Our findings underline the increased implantation rates by use of ERA and endometrial immune profiling in patients with multiple implantation failure, either individually or corporately. Moreover, a combination of both could improve their pregnancy outcomes significantly.

Endometrial Elasticity is an Ultrasound Marker for Predicting Clinical Pregnancy Outcomes after Embryo Transfer

Endometrial elasticity is a potential new marker for assessing endometrial receptivity and pregnancy outcomes based on endometrial thickness and type. Currently, little research has been conducted on the elasticity of the endometrium using shear wave elasticity imaging (SWEI). This study aimed to explore whether endometrial elasticity is an ultrasound marker for predicting clinical pregnancy outcomes after embryo transfer. A total of 245 infertile women underwent ultrasonography before embryo transfer at the Peking University Third Hospital. We compared the endometrial elasticity and sub-endometrial blood flow rate using SWEI in the groups with different pregnancy outcomes. Trends in clinical pregnancy outcomes across the quartiles of endometrial elasticity in the fundus of the uterus (E1) were assessed. Logistic regression analysis was performed to obtain odds ratios for clinical pregnancy outcomes based on the quartiles of E1, with or without adjusting for potential confounding variables. Women in the clinical pregnancy group had higher E1 values and sub-endometrial blood flow rates in the uterine fundus than those in the non-pregnancy group. Women in the highest quartile of E1 had the most favorable clinical pregnancy rates. Endometrial elasticity measured using SWEI is a promising ultrasound marker for predicting clinical pregnancy outcomes after embryo transfer.

Chinese medicine Jianpi Antai formula improves pregnancy outcomes of in vitro fertilization-embryo transfer in infertile women

OBJECTIVES

To evaluate the efficacy and safety of Chinese medicine Jianpi Antai formula in infertile women undergoing in vitro fertilization-embryo transfer (IVF-ET).

METHODS

A total of 300 infertile women who underwent 2 frozen embryo transfer procedures at the Reproductive Medicine Center, Sir Run Run Shaw Hospital were included in the study. The participants were randomly divided into study group and control group. The study group received routine medication plus the Jianpi Antai formula during the period of embryo transfer, while the control group received routine medication only. The general condition, embryo implantation rate, clinical pregnancy rate, live birth rate, and the blood routine and liver and kidney function were evaluated and compared between two groups.

RESULTS

There were 277 cases who completed the study, including 134 in the study group and 143 in the control group. The embryo implantation rate (68.7% vs. 55.9%), the clinical pregnancy rate (56.7% vs. 44.8%) and the live birth rate (50.7% vs. 37.8%) in the study group were all higher than those in the control group (all P<0.05). Subgroup analysis revealed that in patients of advanced age (≥35 years) and those with decreased ovarian reserve function (anti-Müllerian hormone <1.68 ng/mL), the embryo implantation rate, clinical pregnancy rate, and live birth rate in the study group were all higher than those in the control group (all P<0.05). During the follow-up period, there were no abnormalities in the basic vital signs of both groups, and no adverse events were reported.

CONCLUSIONS

Jianpi Antai formula can safely improve the embryo implantation rate in infertile women undergoing IVF-ET, reduce the embryo miscarriage rate, increase the live birth rate as well as improve the clinical outcomes.

The reproductive potential of vitrified-warmed euploid embryos declines following repeated uterine transfers

BACKGROUND

Recurrent implantation failure (RIF) represents a vague clinical condition with an unclear diagnostic challenge that lacks solid scientific underpinning. Although euploid embryos have demonstrated consistent implantation capabilities across various age groups, a unanimous agreement regarding the advantages of preimplantation genetic testing for aneuploidy (PGT-A) in managing RIF is absent. The ongoing discussion about whether chromosomal aneuploidy in embryos significantly contributes to recurrent implantation failure remains unsettled. Despite active discussions in recent times, a universally accepted characterization of recurrent implantation failure remains elusive. We aimed in this study to measure the reproductive performance of vitrified-warmed euploid embryos transferred to the uterus in successive cycles.

METHODS

This observational cohort study included women (n = 387) with an anatomically normal uterus who underwent oocyte retrieval for PGT-A treatment with at least one biopsied blastocyst, between January 2017 and December 2021 at a university-affiliated public fertility center. The procedures involved in this study included ICSI, blastocyst culture, trophectoderm biopsy and comprehensive 24-chromosome analysis of preimplantation embryos using Next Generation Sequencing (NGS). Women, who failed a vitrified-warmed euploid embryo transfer, had successive blastocyst transfer cycles (FET) for a total of three using remaining cryopreserved euploid blastocysts from the same oocyte retrieval cycle. The primary endpoints were sustained implantation rate (SIR) and live birth rate (LBR) per vitrified-warmed single euploid embryo. The secondary endpoints were mean euploidy rate (m-ER) per cohort of biopsied blastocysts from each patient, as well as pregnancy and miscarriage rates.

RESULTS

The mean age of the patient population was 33.4 years (95% CI 32.8-33.9). A total of 1,641 embryos derived from the first oocyte retrieval cycle were biopsied and screened. We found no associations between the m-ER and the number of previous failed IVF cycles among different ranges of maternal age at oocyte retrieval (P = 0.45). Pairwise comparisons showed a significant decrease in the sustained implantation rate (44.7% vs. 30%; P = 0.01) and the livebirth rate per single euploid blastocyst (37.1% vs. 25%; P = 0.02) between the 1st and 3rd FET. The cumulative SIR and LBR after up to three successive single embryo transfers were 77.1% and 68.8%, respectively. We found that the live birth rate of the first vitrified-warmed euploid blastocyst transferred decreased significantly with the increasing number of previously failed IVF attempts by categories (45.3% vs. 35.8% vs. 27.6%; P = 0.04). A comparable decrease in sustained implantation rate was also observed but did not reach statistical significance (50% vs. 44.2 vs. 37.9%; P = NS). Using a logistic regression model, we confirmed the presence of a negative association between the number of previous IVF failed attempts and the live birth rate per embryo transfer cycle (OR = 0.76; 95% CI 0.62-0.94; P = 0.01).

CONCLUSIONS

These findings are vital for enhancing patient counseling and refining management strategies for individuals facing recurrent implantation failure. By tailoring interventions based on age and ovarian reserve, healthcare professionals can offer more personalized guidance, potentially improving the overall success rates and patient experiences in fertility treatments.

TRIAL REGISTRATION NUMBER

N/A.

Using feature optimization and LightGBM algorithm to predict the clinical pregnancy outcomes after in vitro fertilization

Background

According to a recent report by the WHO, approximately 17.5\% (about one-sixth) of the global adult population is affected by infertility. Consequently, researchers worldwide have proposed various machine learning models to improve the prediction of clinical pregnancy outcomes during IVF cycles. The objective of this study is to develop a machine learning(ML) model that predicts the outcomes of pregnancies following in vitro fertilization (IVF) and assists in clinical treatment.

Methods

This study conducted a retrospective analysis on provincial reproductive centers in China from March 2020 to March 2021, utilizing 13 selected features. The algorithms used included XGBoost, LightGBM, KNN, Naïve Bayes, Random Forest, and Decision Tree. The results were evaluated using performance metrics such as precision, recall, F1-score, accuracy and AUC, employing five-fold cross-validation repeated five times.

Results

Among the models, LightGBM achieved the best performance, with an accuracy of 92.31%, recall of 87.80%, F1-score of 90.00\%, and an AUC of 90.41%. The model identified the estrogen concentration at the HCG injection(etwo), endometrium thickness (mm) on HCG day(EM TNK), years of infertility(Years), and body mass index(BMI) as the most important features.

Conclusion

This study successfully demonstrates the LightGBM model has the best predictive effect on pregnancy outcomes during IVF cycles. Additionally, etwo was found to be the most significant predictor for successful IVF compared to other variables. This machine learning approach has the potential to assist fertility specialists in providing counseling and adjusting treatment strategies for patients.

Uterine Nodal expression supports maternal immunotolerance and establishment of the FOXP3+ regulatory T cell population during the preimplantation period

Pregnancy success is dependent on the establishment of maternal tolerance during the preimplantation period. The immunosuppressive function of regulatory T cells is critical to limit inflammation arising from implantation of the semi-allogeneic blastocyst. Insufficient maternal immune adaptations to pregnancy have been frequently associated with cases of female infertility and recurrent implantation failure. The role of Nodal, a secreted morphogen of the TGFβ superfamily, was recently implicated during murine pregnancy as its conditional deletion (NodalΔ/Δ) in the female reproductive tract resulted in severe subfertility. Here, it was determined that despite normal preimplantation processes and healthy, viable embryos, NodalΔ/Δ females had a 50% implantation failure rate compared to NodalloxP/loxP controls. Prior to implantation, the expression of inflammatory cytokines MCP-1, G-CSF, IFN-γ and IL-10 was dysregulated in the NodalΔ/Δ uterus. Further analysis of the preimplantation leukocyte populations in NodalΔ/Δ uteri showed an overabundance of infiltrating, pro-inflammatory CD11bhigh Ly6C+ macrophages coupled with the absence of CD4+ FOXP3+ regulatory T cells. Therefore, it is proposed that uterine Nodal expression during the preimplantation period has a novel role in the establishment of maternal immunotolerance, and its dysregulation should be considered as a potential contributor to cases of female infertility and recurrent implantation failure.

Acupuncture benefits to women with recurrent implantation failure: A propensity score-matched cohort study

Objectives

The current study aims to assess the effectiveness of acupuncture in improving the live birth rate (LBR), ongoing pregnancy rate (OPR), clinical pregnancy rate (CPR), biochemical pregnancy rate (BPR), and pregnancy loss (early abortion rate, late abortion rate, ectopic pregnancy rate) in patients with recurrent implantation failure (RIF).

Design

This retrospective study compares the outcomes of patients with RIF who underwent frozen embryo transfer (FET) with or without acupuncture.

Setting

The medical records of patients diagnosed with RIF and visiting Chengdu Xi'nan Gynecological Hospital between January 2018 and June 2021 were reviewed. The Chengdu Xi'nan Gynecological Hospital Ethics Committee approved this retrospective study (No. 2021-029).

Participants

A total of 923 patients with RIF who underwent FET were included in this study. The patients were divided into two groups: the Acupuncture (n = 303) and the Non-acupuncture groups (n = 620).

Exposure

The Acupuncture group consisted of 303 RIF patients who received acupuncture therapy in addition to standard hormone replacement therapy (HRT)/delayed hormone replacement therapy (d-HRT) for FET. The Non-acupuncture group consisted of 620 RIF patients who received only standard HRT/d-HRT for FET.

Primary and secondary outcome measures

The primary outcome was the LBR. The secondary outcome referred to OPR, CPR, BPR, and pregnancy loss.

Results

The Acupuncture group had significantly higher BPR (P = 0.08) and CPR (P = 0.049) than the Non-acupuncture group. A potentially higher LBR (P = 0.16) and OPR (P = 0.248) were observed in the Acupuncture group than in the Non-acupuncture group. However, the survival analysis did not show that acupuncture significantly promoted live birth.

Conclusions

Acupuncture is an appropriate adjunctive technique in the in vitro fertilization process as it improves biochemical and clinical pregnancies. Therefore, it is necessary to be cautious about the role of acupuncture throughout the whole pregnancy cycle.

Intrauterine Infusion of Leukocyte-Poor Platelet-Rich Plasma Is an Effective Therapeutic Protocol for Patients with Recurrent Implantation Failure: A Retrospective Cohort Study

BACKGROUND

The clinical application of autologous leukocyte-poor platelet-rich plasma (LP-PRP) in patients with recurrent implantation failure (RIF) is rare. This retrospective observational cohort study aimed to evaluate the efficacy of LP-PRP intrauterine infusion in patients with RIF.

METHODS

Patients with RIF undergoing frozen embryo transfer (FET) from January 2019 to December 2021 (n = 118) were enrolled, with those undergoing LP-PRP intrauterine infusion as the PRP group (n = 64), and those receiving no LP-PRP treatment as the control group (n = 54). The beta-human chorionic gonadotropin (β-hCG)-positive rate, clinical pregnancy rate (CPR), live birth rate (LBR), and miscarriage rate (MR) per ET cycle were compared.

RESULTS

The β-hCG-positive rate (57.8% vs. 38.9%, p = 0.041), CPR (45.3% vs. 24.5%, p = 0.022), and LBR per ET cycle (42.2% vs. 18.5%, p = 0.009) were higher in the PRP group than in the control group, and the three variables (62.5% vs. 41.2%, p = 0.040, 47.5% vs. 23.5%, p = 0.033, and 47.5% vs. 20.6%, p = 0.027) in the PRP group transferred with the blastocyst-stage embryos were also higher than those in the control group. The MR was similar in all groups.

CONCLUSIONS

The LP-PRP treatment could improve the β-hCG-positive rate, CPR, and LBR in RIF patients undergoing FET cycles.

Transcriptomic analysis of mid-secretory endometrium reveals essential immune factors associated with pregnancy after single euploid blastocyst transfer

PURPOSE

Implantation is a limiting factor for treatment success in assisted reproduction. Both embryonic and endometrial factors contribute to implantation. Embryonic factors have often been ignored in previous studies about the role of endometrium in implantation. In this study, we sought to identify the endometrial genes associated with negative pregnancy outcomes following the transfer of a single euploid blastocyst.

METHODS

Computational analyses of the transcriptomes of mid-secretory endometria from nine pregnant and seven non-pregnant patients in a cycle preceding the transfer of a single euploid blastocyst in a vitrified-warmed cycle were performed.

RESULTS

Principal component analysis of two reported endometrial receptivity gene sets showed close clustering of the pregnant and non-pregnant samples. Differential gene expression analysis and co-expression module analysis identified 131 genes associated with the pregnancy status. The endometrial signatures identified highlight the importance of immune and metabolic regulation in pregnancy outcome. Network analysis identified 20 hub genes that could predict pregnancy outcomes with 88.9% sensitivity and 85.7% specificity. Single-cell gene expression analysis highlighted the regulation of endometrial natural killer (NK) cells, T cells, and macrophages during embryo implantation. Immune cell abundance analysis supported the dysregulation of cytotoxic immune cells in the endometria of non-pregnant women.

CONCLUSIONS

We reported the first endometrial gene signature associated with pregnancy after elimination of embryo aneuploidy and highlighted the importance of the endometrial immune microenvironment and metabolic status in pregnancy outcomes.

Comparison of the Effects of GMCSF-Containing and Traditional Culture Media on Embryo Development and Pregnancy Success Rates

OBJECTIVE

 The use of granulocyte macrophage colony-stimulating factor (GM-CSF)-containing medium, which is a commercial medium that is used for cultivation of embryos in in vitro fertilization (IVF) treatments, has been suggested to increase the efficiency of this procedure in patients with previous multiple unsuccessful attempts. In this retrospective study, we analyzed GM-CSF-containing embryo culture media compared with traditional culture media in terms of development of embryos, pregnancy, and ongoing pregnancy success and live birth rates.

METHODS

 This is a prospective case control study conducted in a single center. A total of 131 unexplained infertility patients were included in the study. A cohort of 69 patients whose embryos were cultured in GM-CSF-containing medium and a control group of 62 age-matched patients whose embryos were cultured in conventional Sage One Step medium were included in the study. The major study outcomes were achievement of pregnancy and ongoing pregnancy rate at 12 weeks of gestation.

RESULTS

 The pregnancy and ongoing pregnancy rates of the patients whose embryos were cultured in GM-CSF-containing medium were 39.13% and 36.23%, respectively. These were higher than the rates of the control group, which were 30.65% and 29.03%, respectively, although this difference was not statistically significant. In addition, the 5^th-day embryo transfer percentage in the GM-CSF group was higher than in the control group (34.78% versus 27.4%).

CONCLUSION

 The main findings of our study were that there was no difference between the GM-CSF-enhanced medium and the control group in terms of our major study outcomes. However, blastomere inequality rate and embryo fragmentation rates were lower in the GM-CSF group.

Management of recurrent implantation failure: British Fertility Society policy and practice guideline

Recurrent implantation failure (RIF) is defined as the absence of a positive pregnancy test after three consecutive transfers of good quality embryos. There remains significant variation in clinical practice in the management of RIF. This British Fertility Society (BFS) Policy and Practice guideline analyses the evidence for investigations and therapies that are employed in RIF and provides recommendations for clinical practice and for further research. Evidence for investigations of sperm and egg quality, uterine and adnexal factors, immunological factors and thrombophilia, endocrine conditions and genetic factors and for associated therapies have been evaluated. This guideline has been devised to assist reproductive medicine specialists and patients in making shared decisions concerning management of RIF. Finally, suggestions for research towards improving understanding and management of RIF have also been provided.

FHL1 mediates HOXA10 deacetylation via SIRT2 to enhance blastocyst-epithelial adhesion

Recurrent implantation failure (RIF) is a rather thorny problem in the clinical practice of assisted reproductive technology. Due to the complex aetiology of RIF, its pathogenesis is far from fully understood, and there is no effective treatment available. Here, We explored the regulatory mechanism of the four half-domains of LIM domain 1 (FHL1), which is significantly downregulated in the endometrium of RIF patients, in blastocyst-epithelial adhesion. Indeed, FHL1 expression was dramatically increased in normal female mid-secretory endometrial epithelial cells and was abnormally reduced in RIF patients. Furthermore, FHL1 overexpression promoted blastocyst-epithelial adhesion, and interfering with FHL1 expression in the mouse uterus significantly inhibited embryo implantation. Mechanistically, FHL1 did not regulate HOXA10 mRNA expression but increased HOXA10 protein stability and activated HOXA10, thereby promoting its regulation of downstream gene expression and the β3 integrin/FAK pathway. Meanwhile, FHL1 regulates HOXA10 function by increasing HOXA10 deacetylation through enhanced binding of HOXA10 and SIRT2. SIRT2-specific inhibitors can significantly inhibit this effect. In the endometrial epithelial cells of RIF patients, the correlation between FHL1 and HOXA10 and its downstream target genes has also been verified. Finally, our data indicated FHL1 is a regulatory molecule that promotes blastocyst-epithelial adhesion. Altogether, downstream dysfunction due to aberrant FHL1 expression is an important molecular basis for embryo implantation failure in patients with RIF and to provide new potential therapeutic targets.

[HLA-C KIR interactions and placental defects: Implications in ART pregnancy issues]

OBJECTIVE

The aim of this review is to update data concerning the impact of HLA-C KIR system on placental disorders and assess the involvement on ART clinical outcomes.

METHOD

Ensuring the maintenance of human pregnancy requires the set up of immunological tolerance to prevent foetus rejection. This phenomenon involves different actors of the immune system: among them, uterine NK cells (uNK) hold specific KIR (killer-cell immunoglobulin-like) receptors linking to HLA molecules on the surface of trophoblastic cells at implantation. Many studies provided evidence that the specific interaction between maternal KIR and foetal HLA-C could influence the process of placentation; according to the KIR haplotype and the type of HLA-C, the interaction could be detrimental for placental function. We reviewed the latest data available regarding HLA-C KIR interactions and ART outcomes.

RESULTS

The available results highlight a significant increase of preeclampsia risk and recurrent miscarriages when the maternal inhibitory haplotype KIR AA is present, this risk is all the more enhanced when the interaction occurs with foetal HLA-C2. Recent data suggest the consequences of this detrimental interaction in case of DET (double embryo transfer) or use of donor's oocytes in ART practice. On the other hand, maternal KIR AB or BB haplotypes haven't been related to an additional obstetrical risk, as well as the foetal HLA-C1 homozygous allotype.

CONCLUSION

Despite the existence of many confoundings in current literature on the subject, interaction between maternal KIR and foetal HLA-C represent a promising target lead to broaden the spectrum of placental defects etiologies, especially in the reproductive health area.

Comprehensive Analysis of circRNA-Mediated ceRNA Regulatory Networks in relation to Recurrent Implantation Failure

Recurrent implantation failure (RIF) is attributed to endometrial receptivity dysfunction with many unanswered questions. Up to now, there is no explanation for RIF, and therapeutic strategies are usually limited to supportive care. In this study, we differentially analyzed the raw data deposited in three eligible microarray datasets, GSE111974, GSE121219, and GSE147442 to screen DE-mRNAs, DE-miRNAs, and DE-circRNAs, respectively. The value of log2-fold change |log2FC| ≥ 1 and the adjusted p value < 0.05 were considered differentially expressed between RIF and fertile control. We found 350 DE-mRNAs, 43 DE-miRNAs, and 1968 DE-circRNAs between RIF and fertile control. The PPI network identified 6 hub genes with degree ≥10, KDR, AGT, POSTN, TOP2A, RRM2, and PTGS2, in RIF. KDR, AGT, POSTN, TOP2A, and RRM2 were downregulated in endometrial tissue samples of RIF compared with those of fertile control, while PTGS2 was upregulated in endometrial tissue samples of RIF compared with those of fertile control. According to the ceRNA hypothesis, 15 groups of ceRNA network based on 10 circRNAs, hsa_circ_001572, hsa_circ_001884, hsa_circ_001375, hsa_circ_001449, hsa_circ_000029, hsa_circ_001168, hsa_circ_000210, hsa_circ_001484, hsa_circ_001698, and hsa_circ_000089 were constructed in RIF. In conclusion, the present study examined the possible role of circRNAs and their related ceRNA network involved in the pathogenesis of RIF.

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.

The role of extracellular matrix on unfavorable maternal–fetal interface: focusing on the function of collagen in human fertility

Extracellular matrix (ECM) is characterized as widespread, abundant, and pluripotent. Among ECM members, collagen is widely accepted as one of the most prominent components for its essential structural property that can provide a scaffold for other components of ECM and the rich biological functions, which has been extensively used in tissue engineering. Emerging evidence has shown that the balance of ECM degradation and remodeling is vital to regulations of maternal–fetal interface including menstrual cycling, decidualization, embryo implantation and pregnancy maintenance. Moreover, disorders in these events may eventually lead to failure of pregnancy. Although the improvement of assisted conception and embryo culture technologies bring hope to many infertile couples, some unfavorable outcomes, such as recurrent implantation failure (RIF), recurrent pregnancy loss (RPL) or recurrent miscarriage (RM), keep troubling the clinicians and patients. Recently, in vitro three-dimensional (3D) model mimicking the microenvironment of the maternal–fetal interface is developed to investigate the physiological and pathological conditions of conception and pregnancy. The progress of this technology is based on clarifying the role of ECM in the endometrium and the interaction between endometrium and conceptus. Focusing on collagen, the present review summarized the degradation and regulation of ECM and its role in normal menstruation, endometrium receptivity and unsatisfying events occurring in infertility treatments, as well as the application in therapeutic approaches to improve pregnancy outcomes. More investigations about ECM focusing on the maternal–fetal interface interaction with mesenchymal stem cells or local immunoregulation may inspire new thoughts and advancements in the clinical application of infertility treatments.

Graphical abstract

Intrauterine administration of peripheral blood mononuclear cells (PBMCs) improves embryo implantation in mice by regulating local Treg/Th17 cell balance

Immune imbalance of Treg/Th17 cells may contribute to recurrent implantation failure (RIF) during in vitro fertilization and embryo transfer (IVF-ET). In this study, we sought to determine the effect of intrauterine administration of mouse PBMCs prior to embryo implantation on endometrial receptivity and embryo implantation, and examine the underlying mechanism of Treg/Th17 cell balance following intrauterine administration of PBMCs. Pregnant mice were randomly divided into three groups: control group, embryo implantation dysfunction (EID) group, and EID with PBMCs group, and the number of embryo implantation sites was recorded during early pregnancy (Pd7.5). The balance of Treg/Th17 cells in the peripheral blood, spleen, and local implantation sites was detected during the peri-implantation period (Pd4.0) and early pregnancy (Pd7.5). The EID group demonstrated a significant decrease in the number of embryo implantation sites, while the EID with PBMCs group demonstrated higher number of embryo implantation sites compared to the EID group. The balance of Treg/Th17 cells in the peripheral blood and spleen tissues was not significantly different between the aforementioned groups. However, the local uterine ratio of the Treg/Th17 cells increased in the EID with PBMCs group compared to that in the EID group. Collectively, we found that intrauterine administration of PBMCs prior to embryo implantation effectively promotes embryo implantation rates. This may be attributed to the improvement in the local immune balance of Treg and Th17 cells compared with the overall immune balance.

Does Microfluidic Sperm Sorting Affect Embryo Euploidy Rates in Couples with High Sperm DNA Fragmentation?

Male infertility contributes as the main factor in 30-50% of infertility cases. Conventional methods for sperm preparation have induced questioning of sperm recovery rates. The microfluidic sperm sorting (MSS) technique selects highly motile sperm with lower levels of SDF (sperm DNA fragmentation) compared to conventional sperm sorting techniques. This study aimed to determine whether utilizing this technique will reveal better embryo quality and euploidy rates in couples with repeated implantation failure (RIF) and high SDF in a new PGT-A (preimplantation genetic testing for aneuploidies) cycle. This retrospective study included couples referred to PGT-A for previous repeated ART (assisted reproductive techniques) cycle failures and with high SDF. In their new cycles, couples who accepted the technique were assigned to the MSS group, and the rest were managed with DGC (density-gradient centrifugation). Two groups were compared in terms of fertilization and euploidy rates, clinical miscarriage and live birth rates, the total number of blastocysts, and top quality blastocysts. There was no difference between the groups regarding fertilization rates, euploidy rates, clinical miscarriage, and live birth rates. The total number of blastocysts and top quality blastocysts were significantly higher in the MSS group. The MSS technique provides a higher number of top-quality blastocysts than DGC; however, neither euploidy nor live birth rates improved. Studies focusing on confounding factors to embryonic genomic status in the presence of high SDF are needed.

Iron overload compromises preimplantation mouse embryo development

We and others have previously shown that abnormal pelvic environment plays an important role in the unexplained infertility of endometriosis. However, whether iron overload caused by ectopic periodic bleeding found in patients with endometriosis participates in endometriosis-associated reproductive failure is unknown. This study aimed to investigate effects of iron at level relevant to pelvic iron overload on the development of preimplantation mouse embryo. Two-cell embryos were collected, and cultured to blastocysts in G1/G2 medium supplemented with iron alone or in combination with iron chelator. The development rates, ATP level, mitochondrial membrane potential (MMP), reactive oxygen species level (ROS), and apoptotic and ferroptotic indices were compared between control and iron treatments across each specific developmental stage. Prolonged exposure to iron remarkably impaired early embryo development in vitro by hampering blastocyst formation (P < 0.001), which could be partly restored by iron chelator (P < 0.001). The arrest of embryo development was linked with iron-initiated mitochondrial dysfunction with reduction of ATP generation and MMP (P < 0.05 and P < 0.001, respectively). Impaired mitochondria altered ROS accumulation post-iron exposure at morula stage and blastocyst stage (P < 0.05). Moreover, Iron-exposed blastocyst stage embryos showed higher apoptotic and ferroptotic rates (P < 0.001 and P < 0.05, respectively). Our results highlight that pathologically relevant level of iron compromises preimplantation mouse embryo development by disrupting mitochondrial function and triggering both apoptosis and ferroptosis, which implicates that excess iron found in peritoneal fluid of women with endometriosis likely participates in endometriosis-associated reproductive failure.

A comparative evaluation of subendometrial and intrauterine platelet-rich plasma treatment for women with recurrent implantation failure

OBJECTIVE

To compare the effectiveness of treatment with autologous activated platelet-rich plasma (PRP), administered to either the subendometrium (SE-PRP) or endometrial surface (intrauterine; IU-PRP), against controls.

DESIGN

Prospective observational cohort study.

SETTING

Tertiary fertility unit.

PATIENTS

Women aged <40 years with a history of recurrent implantation failure undergoing frozen embryo transfer (FET) (n = 318).

INTERVENTIONS

In SE-PRP, PRP was injected into the subendometrial space transvaginally in the luteal phase of the previous cycle of embryo transfer under ultrasound guidance (n = 55). In IU-PRP, PRP was administered during the index FET cycle when the endometrium was approximately 7 mm (n = 109). Both SE-PRP and IU-PRP groups were administered 300 μg of granulocyte colony-stimulating factor (G-CSF) subcutaneously once a day for 3 days to boost white blood cells (WBC) and growth factor production in the PRP sample. The control group consisted of women who did not choose PRP treatment and underwent standard FET with no intervention (n = 154).

MAIN OUTCOME MEASURES

Ongoing pregnancy rate or live birth rate (OPR/LBR) per transfer cycle, clinical pregnancy rate (CPR) per transfer cycle, and miscarriage rate.

RESULTS

As a result, OPR/LBR was higher in the SE-PRP (22/55, 40%) and IU-PRP (45/109, 41.3%) groups than that in the control group (34/154, 22.1%). It was similar between the SE-PRP and IU-PRP groups. Moreover, CPR showed a similar trend with a higher rate in the SE-PRP (28/55, 51%) and IU-PRP (57/109, 52.3%) groups than that in the controls (52/154, 33.8%). No statistical difference in the CPR was noted between the SE-PRP and IU-PRP groups. The miscarriage rate was similar in all three groups (14/55, 25.45%; 25/109, 22.23%; and 34/154, 22.07%, respectively).

CONCLUSION

In women with a history of recurrent implantation failure, PRP treatment appears to improve FET outcome with an increase in OPR/LBR. However, SE-PRP treatment does not offer any advantage over lesser invasive IU-PRP treatment.

Uterine natural killer cells: from foe to friend in reproduction

BACKGROUND

Recurrent miscarriage and pre-eclampsia are common reproductive disorders, but their causes are often unknown. Recent evidence has provided new insight into immune system influences in reproductive disorders. A subset of lymphocytes of the innate immune system known as uterine natural killer (uNK) cells are now recognized as fundamental to achieving embryo implantation and successful pregnancy, but were initially attributed a bad reputation. Indeed, immune therapies have been developed to treat the 'exaggerated' immune response from uNK cells. These treatments have been based on studies of peripheral blood natural killer (pbNK) cells. However, uNK cells and pbNK cells have different phenotypic and functional characteristics. The functions of uNK cells are closely related to their interactions with the extravillous trophoblast cells (EVTs) and spiral arteries, which underlie an essential role in regulating vascular function, controlling trophoblast invasion and promoting placental development. EVTs express MHC molecules of class I HLA-C/E/G/F, while uNK cells express, among other receptors, killer cell immunoglobulin-like receptors (KIRs) that bind to HLA-C or CD94/NKG2A inhibitory receptors, and then bind HLA-E. Associations of certain KIR/HLA-C combinations with recurrent miscarriage, pre-eclampsia, and foetal growth restriction and the interactions between uNK cells, trophoblasts and vascular cells have led to the hypothesis that uNK cells may play a role in embryo implantation.

OBJECTIVE AND RATIONALE

Our objective was to review the evolution of our understanding of uNK cells, their functions, and their increasingly relevant role in reproduction.

SEARCH METHODS

Relevant literature through June 2020 was retrieved using Google Scholar and PubMed. Search terms comprised uNK cells, human pregnancy, reproductive failure, maternal KIR and HLA-C, HLA-E/G/F in EVT cells, angiogenic cytokines, CD56+ NK cells, spiral artery, oestrogen and progesterone receptors, KIR haplotype and paternal HLA-C2.

OUTCOMES

This review provides key insights into the evolving conceptualization of uNK cells, from their not-so-promising beginnings to now, when they are considered allies in reproduction. We synthesized current knowledge about uNK cells, their involvement in reproduction and their main functions in placental vascular remodeling and trophoblast invasion. One of the issues that this review presents is the enormous complexity involved in studying the immune system in reproduction. The complexity in the immunology of the maternal-foetal interface lies in the great variety of participating molecules, the processes and interactions that occur at different levels (molecular, cellular, tissue, etc.) and the great diversity of genetic combinations that are translated into different types of responses.

WIDER IMPLICATIONS

Insights into uNK cells could offer an important breakthrough for ART outcomes, since each patient could be assessed based on the combination of HLA and its receptors in their uNK cells, evaluating the critical interactions at the materno-foetal interface. However, owing to the technical challenges in studying uNK cells in vivo, there is still much knowledge to gain, particularly regarding their exact origin and functions. New studies using novel molecular and genetic approaches can facilitate the identification of mechanisms by which uNK cells interact with other cells at the materno-foetal interface, perhaps translating this knowledge into clinical applicability.

Recurrent implantation failure: how common is it?

PURPOSE OF REVIEW

To clarify a lingering issue, the true incidence of repeated implantation failures (RIF) in women undergoing successive frozen euploid single embryo transfers (FE-SET).

RECENT FINDINGS

As not all Assisted reproductive techinique (ART) attempts are crowned by success, it has been questioned since incept of ART whether failures resulted from an embryonic or endometrial cause. RIF has received no precise definition but a trend has existed toward setting a more stringent definition, as reproductive biology has become more effective and ART success rates improved. No scientific society has yet convened on a universally accepted definition. The advent of effective and well tolerated pregestational testing of embryos for aneuploidy (PGT-A) has allowed to not transfer aneuploid embryos, which are bound not to succeed. This, therefore, justify revisiting the concept of RIF when only euploid embryos are transferred.

SUMMARY

Contrary to lingering beliefs, the results of our study indicate that RIF following three successive euploid embryo transfers in a morphologically normal endometrium is a rare occurrence (<5%). This supports the concept that ART failures mainly result from embryonic causes. Our data also propose a new - functional - definition of RIF being an ART failure following 3 successive FE-SET attempts. Our findings, therefore seriously question the soundness of prescribing the often complex and expensive endometrial testing procedures that largely publicized for treating RIF.

4-Hydroxyestradiol improves mouse embryo quality, epidermal growth factor-binding capability in vitro and implantation rates

Embryo implantation in the uterus is a critical step to achieve success following ART. Despite favorable uterine conditions, a great number of good quality embryos fail to implant, often for reasons that are unknown. Hence, improving the implantation potential of embryos is a subject of great interest. 4-Hydroxyestradiol (4-OH-E2), a metabolic product of estradiol produced by endometrial cells, plays a key role in endometrial-embryonic interactions that are necessary for implantation. Nonetheless, the effects of 4-OH-E2 on embryos obtained in vitro have not been yet described. This study was designed to determine whether culture media enriched in 4-OH-E2 could improve the quality and implantation rate of embryos obtained in vitro, using both in vitro and in vivo models. We also analyzed its effects on the epidermal growth factor (EGF)-binding capability of the embryos. Our results showed that the presence of 4-OH-E2 in the culture media of embryos during the morula to blastocyst transition increases embryo quality and attachment to endometrial cells in vitro. 4-OH-E2 can also improve viable pregnancy rates of mouse embryos produced in vitro, reaching success rates that are similar to those from embryos obtained directly from the uterus. 4-OH-E2 improved the embryos' ability to bind EGF, which could be responsible for the increased embryo implantation potential observed. Therefore, our results strongly suggest that 4-OH-E2 is a strong candidate molecule to supplement human IVF culture media in order to improve embryo implantation. However, further research is required before these findings can be translated with efficacy and safety to fertility clinics.

The Complicated Effects of Extracellular Vesicles and Their Cargos on Embryo Implantation

As a rate-limiting step in pregnancy, embryo implantation is highly dependent on intercellular communication. Extracellular vesicles (EVs) are newly identified to be important in the course of intercellular communication. EVs have been isolated from a wide variety of biofluids and tissues, including plasma, liver, uterine, semen, embryo, etc. The present and future use of EVs not only as biomarkers, but also as targeting drug delivery system, is promisingly pave the way for advanced comprehension of implantation failure in reproductive diseases. However, as the precise mechanisms of EVs in embryo implantation has not been elucidated yet. Herein, we summarize the current knowledge on the diverse effects of EVs from various sources and their cargos such as microRNA, long non-coding RNA, protein, etc. on embryo implantation, and the potential mechanisms of EVs in reproductive diseases such as recurrent implantation failure, polycystic ovary syndrome and endometriosis. It is essential to note that many of the biologically plausible functions of EVs in embryo implantation discussed in present literatures still need further research in vivo.

The impact of a poor quality embryo on the implantation chance of a good quality one when transferred together: A study on double blastocyst transfers

OBJECTIVE

Embryo quality assessment with morphological evaluation remains the first-line method of assessment to select the best embryo for transfer. We aimed to determine if an effect of poor quality embryos on good quality ones exists, whether by a paracrine effect or an adverse endometrial influence, when they are transferred together.

MATERIALS AND METHODS

We included 412 couples, who underwent intracytoplasmic sperm injection (ICSI) cycles in a tertiary IVF center. Single embryo transfer with a good quality embryo and double embryo transfers with a good + poor quality embryo were evaluated. Overall pregnancy (PR) and live birth rates (LBR) were our main outcome measures.

RESULTS

When PR and LBR are compared, there was no statistical significance between single embryo transfer (SET) and double embryo transfer (DET) groups (51.7 % vs 53.7 %, p = 0.620 and 47 % vs 43.1 %, p = 0.117). When the PR and LBRs were compared between SET from poor cohort and DET group, the outcomes were better in DET group (22.1 % vs 53.7 %, p < 0.001 and 22.1 % vs 43.1 %, p < 0.001). The PR and LBRs of SET from good cohort were significantly better than those of DET (64.4 % vs 53.7 %, p < 0.001 and 57.7 % vs 43.1, p < 0.001). When the PR and LBRs of SET from good cohort and SET from poor cohort were compared, better results were obtained in SET from good cohort.

CONCLUSION

The addition of poor quality embryo even is of benefit to the LBR, in the setting of when there is only one good quality blastocyst available for the transfer.

The Impact of Controlled Ovarian Stimulation Hormones on the Metabolic State and Endocannabinoid System of Human Cumulus Cells

Different Follicle Stimulating Hormone (FSH) formulation and Luteinizing Hormone (LH) are used in Assisted Reproductive Technology (ART) to induce follicles development and oocytes maturation, but it is still under debate which protocol is to be preferred. In the present study, the different effects on cumulus cells (CCs) of three controlled ovarian stimulation (COS) protocols, based on urinary FSH, recombinant FSH, or human Menopausal Gonadotropin (hMG) administration, were assessed. CCs were obtained from 42 normal-responders women undergoing COS, randomly divided into three groups according to the used gonadotropin formulation. Differences were found in the expression of genes belonging to the endocannabinoid system (the receptors CNR1, CNR2 and TRPV1, and the enzymes involved in the metabolisms of anandamide, NAPE-PLD and FAAH, and 2-acylglycerol, DAGL and MAGL); consistently, changes in lipid (PPARα, and FASN) and carbohydrate (GLUT1 and GLUT9) metabolisms, in CCs’ macromolecules composition (highlighted by Fourier Transform Infrared Microspectroscopy, FTIRM), and in the number of retrieved oocytes were found. For the first time, statistically significant evidence on the differences related to each COS protocol on the endocannabinoid system, metabolism and macromolecular composition of CCs was found, representing a proof of concept to be further confirmed in a larger cohort of patients.

Evaluation of the endometrial receptivity assay and the preimplantation genetic test for aneuploidy in overcoming recurrent implantation failure

PURPOSE

To evaluate the clinical usefulness of the endometrial receptivity array (ERA) and the preimplantation genetic test for aneuploidy (PGT-A) in patients with severe and moderate recurrent implantation failure (RIF).

DESIGN

A retrospective multicenter cohort study was conducted in patients who failed to achieve implantation following transfer of 3 or more or 5 or more embryos in at least three single embryo transfers; patients were classified as moderate or severe RIF, respectively. Patients with previous RIF were compared based on the testing they received: PGT-A, ERA, or PGT-A+ERA versus a control group with no testing. Mean implantation rate and ongoing pregnancy rates per embryo transfer were considered primary outcomes. Multiple logistic regression analysis was performed and adjusted ORs were calculated to control possible bias.

RESULTS

Of the 2110 patients belonging to the moderate RIF group, those who underwent transfer of euploid embryos after PGT-A had a higher implantation rate than those who did not. Additionally, the PGT-A group had a significantly higher rate of ongoing pregnancy. The same outcomes measured for the 488 patients in the severe RIF group did not reveal any statistically significant improvements. The use of the ERA test did not appear to significantly improve outcomes in either group.

CONCLUSIONS

PGT-A may be beneficial for patients with moderate recurrent implantation failure but not for severe cases. At its current level of development, ERA does not appear to be clinically useful for patients with RIF.

What is the prognosis for a live birth after unexplained recurrent implantation failure following IVF/ICSI?

STUDY QUESTION

What is the cumulative incidence of live birth and mean time to pregnancy (by conception after IVF/ICSI or natural conception) in women experiencing unexplained recurrent implantation failure (RIF) following IVF/ICSI treatment?

SUMMARY ANSWER

In 118 women who had experienced RIF, the reported cumulative incidence of live birth during a maximum of 5.5 years follow-up period was 49%, with a calculated median time to pregnancy leading to live birth of 9 months after diagnosis of RIF.

WHAT IS KNOWN ALREADY

Current definitions of RIF include failure to achieve a pregnancy following IVF/ICSI and undergoing three or more fresh embryo transfer procedures of one or two high quality embryos or more than 10 embryos transferred in fresh or frozen cycles. The causes and optimal management of this distressing condition remain uncertain and a range of empirical and often expensive adjuvant therapies is often advocated. Little information is available regarding the long-term prognosis for achieving a pregnancy.

STUDY DESIGN, SIZE, DURATION

Two hundred and twenty-three women under 39 years of age who had experienced RIF without a known cause after IVF/ICSI treatment in two tertiary referral university hospitals between January 2008 and December 2012 were invited to participate in this retrospective cohort follow up study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All eligible women were sent a letter requesting their consent to the anonymous use of their medical file data and were asked to complete a questionnaire enquiring about treatments and pregnancies subsequent to experiencing RIF. Medical files and questionnaires were examined and results were analysed to determine the subsequent cumulative incidence of live birth and time to pregnancy within a maximum 5.5 year follow-up period using Kaplan Meier analysis. Clinical predictors for achieving a live birth were investigated using a Cox hazard model.

MAIN RESULTS AND THE ROLE OF CHANCE

One hundred and twenty-seven women responded (57%) and data from 118 women (53%) were available for analysis. During the maximum 5.5 year follow up period the overall cumulative incidence of live birth was 49% (95% CI 39-59%). Among women who gave birth, the calculated median time to pregnancy was 9 months after experiencing RIF, where 18% arose from natural conceptions.

LIMITATIONS, REASONS FOR CAUTION

Since only 57% of the eligible study cohort completed the questionnaire, the risk of response bias limits the applicability of the study findings.

WIDER IMPLICATIONS OF THE FINDINGS

This study reports a favorable overall prognosis for achieving live birth in women who have previously experienced RIF, especially in those who continue with further IVF/ICSI treatments. However since 51% did not achieve a live birth during the follow-up period, there is a need to distinguish those most likely to benefit from further treatment. In this study, no clinical factors were found to be predictive of those achieving a subsequent live birth.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the University Medical Center Utrecht, in Utrecht and the Academic Medical Centre, in Amsterdam. NSM has received consultancy and speaking fees and research funding from Ferring, MSD, Merck Serono, Abbott, IBSA, Gedion Richter, and Clearblue. During the most recent 5-year period BCJMF has received fees or grant support from the following organizations (in alphabetic order); Actavis/Watson/Uteron, Controversies in Obstetrics & Gynecology (COGI), Dutch Heart Foundation, Dutch Medical Research Counsel (ZonMW), Euroscreen/Ogeda, Ferring, London Womens Clinic (LWC), Merck Serono, Myovant, Netherland Genomic Initiative (NGI), OvaScience, Pantharei Bioscience, PregLem/Gedeon Richter/Finox, Reproductive Biomedicine Online (RBMO), Roche, Teva, World Health Organisation (WHO).None of the authors have disclosures to make in relation to this manuscript.

Successful pregnancy following the transfer of re-vitrified twice-warmed embryos due to the forced cancellation of the primary FET: A case report

PURPOSE

Embryo cryopreservation represents a central procedure in in-vitro fertilization (IVF) programs. This report documents a Case of a successful pregnancy following the replacement of embryos that had to be re-vitrified due to the forced cancellation of the frozen embryo-transfer (FET).

PRINCIPLE RESULTS

The 37- year-old patient was referred to our Assisted Reproductive Technology (ART) unit for idiopathic infertility and recurrent implantation failures. The collection cycle resulted in 8 grade-A cleavage embryos (8-10 blastomeres), that were all vitrified to prevent ovarian hyperstimulation syndrome (OHSS). The first frozen embryo transfer (FET) ended in a biochemical pregnancy and the second in an ectopic pregnancy. In the third attempt, three embryos were warmed but the provider could not complete the transfer due to cervical stenosis. The two surviving embryos were therefore re-vitrified. The final FET attempt, 4 months later, was successful and ended with the live birth of a healthy female baby.

CONCLUSIONS

The transfer of re-vitrified twice-warmed embryos may represent a possible option when embryo transfer cannot be performed.

The role of prokineticins in recurrent implantation failure

The aim of the present study was to investigate the expression patterns of prokineticins (PROK) and prokineticin receptors (PROKR) in the endometrium of women with recurrent implantation failure (RIF). Fifteen (15) women with RIF and 15 fertile controls were enrolled in this study. Endometrial samples were taken from study participants with an endometrial biopsy cannula during the implantation window. Real time polymerase chain reaction and immunohistochemistry were used to determine PROK/PROKR mRNA expression and protein localization, respectively. PROK1 mRNA levels were 6.09 times higher compared to endometrial samples obtained from women with RIF than in samples obtained from fertile controls, whereas PROKR1 mRNA levels were 2.46 times lower in endometrial samples obtained from women with RIF than in samples from fertile controls. In addition, decreased PROKR1 was supported by immunohistochemistry analysis at protein level. There was no statistically significant difference between women with RIF and fertile controls regarding PROK2 and PROKR2 levels. Altered expression of the PROK1/PROKR1 system could be one of the numerous abnormalities in the endometrium of women with RIF.

Potential impact of maternal vitamin D status on peripheral blood and endometrium cellular immunity in women with recurrent implantation failure

PROBLEM

This study aims to evaluate the modulatory effects of vitamin D on peripheral blood and endometrial cellular immunity in women with recurrent implantation failure (RIF).

METHOD OF STUDY

One hundred and fifty-four women with RIF were identified at a fertility center from January 2018 and March 2019. Blood and endometrium samples were collected during the mid-luteal phase before IVF treatment or pregnancy. The serum vitamin D status, NK cell cytotoxicity, Th1 cytokine production, and endometrial immune cells were detected before and after vitamin D supplementation.

RESULTS

The NK cell cytotoxicity at an effector:target (E:T) ratio of 50:1 or 25:1 was significantly higher in vitamin D insufficiency group (VDI) than those in vitamin D normal group (VDN) (P < .05 each). The percentage of IFN-γ- or TNF-α-producing Th cells was significantly increased in VDI or vitamin D deficiency group (VDD) when compared with VDN (P < .05 each). The percentage of CD68⁺ macrophages on all endometrial cells in VDI and VDD was significantly higher than in VDN (P < .05 each), while no significant differences in the percentage of other endometrial immune cells among the three groups were observed. This dysregulation was significantly reduced with vitamin D supplementation.

CONCLUSION

Our findings highlighted that vitamin D may have an important role in the regulation of not only systemic but also local immune response for optimization of maternal tolerance for implantation in women with RIF. Pre-conception optimization of vitamin D status should be considered in women with RIF.

Transcriptomic changes and potential regulatory mechanism of intrauterine human chorionic gonadotropin co-cultured with peripheral blood mononuclear cells infusion in mice with embryonic implantation dysfunction

Background

This study aimed to explore whether intrauterine infusion of peripheral blood mononuclear cells (PBMCs) could induce favorable transcriptomic changes in the endometrium for embryo implantation and the potential mechanism.

Methods

Twenty-one mice were randomly divided to five groups, including a normal pregnancy (NP) group, an embryo implantation dysfunction (EID) group, an EID with human chorionic gonadotropin (hCG) group, an EID with PBMCs group, and an EID with hCG co-cultured with PBMCs group. The endometrium in the implantation window from mice were collected and determined by RNA sequencing (RNA-Seq), and the expression of significantly different genes with high degree of coincidence was recommended and validated by quantitative real-time polymerase chain reaction (qRT-PCR).

Results

There were totally 1,366 up-regulated and 1,374 down-regulated genes in the EID mice compared with the normal pregnant mice. We selected (fold change ≥2, P<0.05) and verified the candidate genes associated with embryo implantation, immune response and other reproductive processes in previous reports by qRT-PCR. Leukemia inhibitory factor (LIF), solute carrier family 15 member 2 (SLC15A2), retinoic acid receptor responder 1 (RARRES1), vascular cell adhesion molecule 1 (VCAM1) were down-regulated and musculin (MSC), chemokine (C-X-C motif) ligand 14 (CXCL14) were up-regulated significantly in EID group (P<0.05), and the synergistic effects of hCG were seen. In addition, the expression of glucocorticoid receptor (GR)-β in PBMCs of NP mice was higher than that of EID mice, and up-regulated GR-β in EID mice could significantly increase the expression of LIF, SLC15A2, RARRES1 and VCAM1, and decrease the expression of CXCL14 and MSC, which indicated GR-β might be a transcriptional factor of the six genes above.

Conclusions

Intrauterine PBMCs perfusion might improve the performance of impaired endometrial receptivity by regulating LIF, SLC15A2, RARRES1, VCAM1, MSC as well as CXCL14, and hCG could enhance the effect of PBMCs. In addition, GR-β, as a transcriptional factor, could regulate the six genes in PBMCs.

Effect of autologous platelet-rich plasma transfusion in the treatment of infertile women with thin endometrium and its implications in IVF cycles: a literature review

Abstract

Background

Thin endometrium could be a major contributing factor in decreasing pregnancy rates with in-vitro fertilization. Several treatments have been studied in patients with thin endometrium, like hormonal therapy by GnRH-agonist and estrogen. Additionally, vasoactive measures like aspirin, a mix of pentoxifylline, vitamin E, l-arginine, sildenafil, and intrauterine infusion of a growth factor such as G-CSF, and the recent application of regenerative medicine were reported in previous trials.

Main body of the abstract

We discuss here a new modality for thin endometrium treatment using platelet-rich plasma (PRP) administered as an intrauterine infusion. The purpose of this review is to evaluate the effectiveness of PRP in cases of infertility. All relevant articles addressing the use of PRP, published from January 2000 to September 2018, were reviewed and analyzed. The studies published on the PRP treatment model for thin endometrium in the gynecology field were mainly case series, pilot studies, or case reports.

Conclusion

In the current review, we found that the local administration of PRP is significantly effective in increasing pregnancy rates of infertile women with thin endometrium < 6 mm.

Expression of miR-Let-7a, miR-15a, miR-16-1, and their target genes in fresh and vitrified embryos and its surrounding culture media for noninvasive embryo assessment

microRNAs (miRNAs) play a critical role in implantation and development of mouse embryos. In this study, we aim to evaluate the possibility of miRNAs as potential biomarkers in the blastocyst culture to assess embryo quality. We also intend to investigate whether improved clinical outcomes of vitrified embryos agree with altered miRNA expressions. Mouse embryos from in vitro fertilization were vitrified at the two-cell stage. After thawing, the embryos were individually cultured and developed to the blastocyst stage. We used quantitative real-time polymerase chain reaction to evaluate miRNA expression levels in both vitrified and fresh groups, and culture medium (CM). The fibronectin binding assay was performed to examine for blastocyst attachment. The findings showed reduced expressions of miR-16-1 (0.2 ± 0.06) and miR-Let-7a (0.65 ± 0.1) after vitrification compared to fresh embryos. We observed significant upregulation of the target genes Vav3 (4.33 ± 0.25), integrin β-3 (Itg β3; 4.73 ± 0.2), and Bcl2 (2.29 ± 0.16) in the vitrified embryos compared to the fresh groups. Evaluation of blastocyst CM showed upregulation of miR-Let-7a (15.68 ± 0.89), miR-16-1 (16.18 ± 0.75), and miR-15a (13.36 ± 0.73) in the vitrified group in comparison to the fresh blastocysts (P < .05). The expression levels of miR-16-1 (3.28 ± 0.63), miR-15a (5.91 ± 0.38), and miR-Let-7a (9.07 ± 0.6) in CM of the vitrified blastocysts conducted on fibronectin were significantly higher than the fresh group (P < .05).This study showed that vitrification of embryos changes implantation and proliferation biomarkers. In addition, upregulated miRNAs in CM could be potentially used for noninvasive early assessment of embryo quality.

The role of immunotherapy in in vitro fertilization and recurrent pregnancy loss: a systematic review and meta-analysis

OBJECTIVE

To study the current evidence on the role of immunotherapy in IVF and in the management of recurrent pregnancy loss (RPL).

DESIGN

Systematic review and meta-analysis.

SETTING

A literature search was performed using MEDLINE, PUBMED, CINAHL, and EMBASE until May 2017. Only randomized controlled trials were included, and a meta-analysis was carried out where appropriate.

PATIENT(S)

Women undergoing IVF treatment with or without a history of recurrent implantation failure and women with idiopathic RPL.

INTERVENTION(S)

Assessment of the efficacy of commonly used immunomodulators such as IV use of [1] immunoglobulin, [2] lymphocyte immunotherapy and [3] intralipid; intrauterine infusion of [4] granulocyte colony-stimulating factor and [5] peripheral blood mononuclear cells; subcutaneous administration of [6] TNF-alpha inhibitors, [7] leukaemia inhibitory factor; and oral administration of [8] glucocorticoids.

MAIN OUTCOME MEASURE(S)

The primary outcomes were live birth rate and miscarriage rate; secondary outcome was clinical pregnancy rate.

RESULT(S)

Of the 7,226 publications identified, 53 were selected during the initial screening; 30 satisfied the selection criteria and were included in this review.

CONCLUSION(S)

The available medical literature shows controversial results about the role of immunotherapy when used for improving reproductive outcomes. This study did not show a role for immunotherapy in improving the live birth rate in women undergoing IVF treatment or in the prevention of idiopathic RPL. Currently, immunotherapy should be used in the context of research and should not be used in routine clinical practice to improve reproductive outcomes.

Towards a gamete matching platform: using immunogenetics and artificial intelligence to predict recurrent miscarriage

The degree of Allele sharing of the Human Leukocyte Antigen (HLA) genes has been linked with recurrent miscarriage (RM). However, no clear genetic markers of RM have yet been identified, possibly because of the complexity of interactions between paternal and maternal genes during embryo development. We propose a methodology to analyse HLA haplotypes from couples either with histories of successful pregnancies or RM. This article describes a method of RM genetic-risk calculation. The proposed HLA representation techniques allowed us to create an algorithm (IMMATCH) to retrospectively predict RM with an AUC = 0.71 (p = 0.0035) thanks to high-resolution typing and the use of linear algebra on peptide binding affinity data. The algorithm features an adjustable threshold to increase either sensitivity or specificity, allowing a sensitivity of 86%. Combining immunogenetics with artificial intelligence could create personalised tools to better understand the genetic causes of unexplained infertility and a gamete matching platform that could increase pregnancy success rates.

The role of abnormal hypermethylation of the HOXA10 and HOXA11 promoters in implantation failures in IVF programs

Objective: The objective of this study is to investigate the association between methylation levels of HOXA10 and HOXA11 promoters, clinical parameters, and implantation outcomes after in vitro fertilization-embryo transfer (IVT-ET) cycles in women with repeated implantation failures and tubal infertility. Methods: Endometrium samples were collected from 34 women during implantation window before IVF-ET cycle to assess methylation status of HOXA10 and HOXA11 promoters using bisulfite sequencing. All participants had a tubal factor of infertility and at least two implantation failures in the anamnesis. A logistic regression model was used to predict the implantation outcome depending on methylation status and clinical parameters. Results: The methylation of CpG-islands of HOXA10 and HOXA11 promoters was identified in 76.5 and 100% of participants, respectively. The median methylation levels did not differ significantly between the groups with different implantation outcomes, but a logistic regression model based on HOXA10 and HOXA11 methylation and clinical parameters allowed to classify the implantation outcomes with the total percentage of correct predictions of 85.19%. Conclusions: Abnormal methylation levels of the HOXA10 and HOXA11 promoters were found in the endometrium of women with tubal infertility and repeated implantation failures. The findings suggest that methylation status could be an important factor of implantation failure during IVF-ET cycles.

Does the dysregulation of matrix metalloproteinases contribute to recurrent implantation failure?

INTRODUCTION

The progress in in vitro fertilization (IVF) techniques for infertility management has led to the investigation of embryo implantation site proteins such as Matrix metalloproteinases (MMPs), which may have a key role in embryo-endometrium crosstalk and in the molecular mechanisms of the embryo implantation. Areas covered: Numerous studies have generated much information concerning the relation between the different proteins at the site of implantation such as cytokines, growth factors, adhesion molecules and MMPs. However, the exact role of the MMPs in embryo implantation and the impact of their dysregulation in recurrent implantation failure have yet to be characterized. Expert commentary: The proteomic investigation of the MMPs and their molecular pathways may enable scientists and clinicians to correct this dysregulation (via appropriate means of prevention and treatment), better manage embryo transfer during IVF cycles, and thus increase the ongoing pregnancy rate.

The interval transfer of a frozen-thawed embryo is more successful than a fresh embryo transfer for women undergoing IVF with recurrent implantation failure after cleavage stage embryo biopsy

BACKGROUND

Recurrent implantation failure (RIF) is repeated unsuccessful embryo transfers (ETs).

AIMS

To identify predictive embryonic markers of implantation in RIF, following pre-implantation genetic screening (PGS) of cleavage stage embryos, after accounting for male and female factors.

MATERIALS AND METHODS

Retrospective analysis of RIF patients undergoing PGS after correction of modifiable causes.

RESULTS

Eighty-four patients underwent 140 in vitro ferilisation cycles. Forty-one cycles were excluded: 12 (no embryo for transfer), four (double ETs) and 25 (no biopsy). Sixty-three patients underwent 99 single euploid ETs (48 fresh, 51 frozen) resulting in 11 biochemical pregnancies, 36 clinical pregnancies (CP), and six miscarriages and 30 live births (LB). Frozen ET was more successful than fresh; respective live birth rate (LBR) and clinical pregnancy rate (CPR), 39.2% versus 20.8%, (P = 0.02), 45.1% versus 27.1% (P = 0.04). LBR and CPR were lower when 5-6 blastomeres were present at embryo biopsy, compared to embryos with ≥7 blastomeres: 15.4% versus 32.6% (P = 0.185) and 15.4% versus 39.5% (P = 0.074) respectively. Serum β human chorionic gonadotropin (βhCG) concentration was greater when a more developed embryo was biopsied (r = 0.448, P = 0.017 and r = 0.476, P = 0.118, fresh and frozen transfers, respectively). Embryo morphokinetic analysis demonstrated faster development to blastocyst stage when more cells were present at biopsy: mean 103.3, 102.2 and 96.0 h for biopsy at the 5-6, 7-8 or ≥9 cell stage respectively (P = 0.040 for difference between 7-8 cells vs ≥9).

CONCLUSIONS

After cleavage stage biopsy, frozen ET was more successful than fresh ET. Chance of conception and serum βhCG concentration correlated with number of cells present at time of biopsy.

The role of the endometrial receptivity array (ERA) in patients who have failed euploid embryo transfers

PURPOSE

Endometrial receptivity issues represent a potential source of implantation failure. The aim of this study was to document our experience with the endometrial receptivity array (ERA) among patients with a history of euploid blastocyst implantation failure. We investigated whether the contribution of the endometrial factor could be identified with the ERA test and if actionable results can lead to improved outcomes.

METHODS

A retrospective review was performed for 88 patients who underwent ERA testing between 2014 and 2017. Reproductive outcomes were compared for patients undergoing frozen embryo transfer (FET) using a standard progesterone protocol versus those with non-receptive results by ERA and subsequent FET according to a personalized embryo transfer (pET) protocol.

RESULTS

Of patients with at least one previously failed euploid FET, 22.5% had a displaced WOI diagnosed by ERA and qualified for pET. After pET, we found that implantation and ongoing pregnancy rates were higher (73.7 vs. 54.2% and 63.2 vs. 41.7%, respectively) compared to patients without pET, although differences were not statistically significant.

CONCLUSIONS

Our experience demonstrates that a significant proportion of patients with a history of implantation failure of a euploid embryo have a displaced WOI as detected by the ERA. For these patients, pET using a modified progesterone protocol may improve the outcomes of subsequent euploid FET. Larger randomized studies are required to validate these results.