Unexplained Recurrent Implantation Failure Research Articles

Does recurrent implantation failure exist? Prevalence and outcomes of five consecutive euploid blastocyst transfers in 123987 patients.

What are the clinical pregnancy and live birth rates in women who underwent up to two more euploid blastocyst transfers after three failures in the absence of another known factor that affects implantation? The fourth and fifth euploid blastocyst transfers resulted in similar live birth rates of 40% and 53.3%, respectively, culminating in a cumulative live birth rate of 98.1% (95% CI = 96.5-99.6%) after five euploid blastocyst transfers. The first three euploid blastocysts have similar implantation and live birth rates and provide a cumulative live birth rate of 92.6%. An international multi-center retrospective study was conducted at 25 individual clinics. The study period spanned between January 2012 and December 2022. A total of 123987 patients with a total of 64572 euploid blastocyst transfers were screened for inclusion. Patients with a history of any embryo transfer at another clinic, history of any unscreened embryo transfer at participating clinics, parental karyotype abnormalities, the use of donor oocytes or a gestational carrier, untreated intracavitary uterine pathology (e.g. polyp, leiomyoma), congenital uterine anomalies, adenomyosis, communicating hydrosalpinx, endometrial thickness <6 mm prior to initiating of progesterone, use of testicular sperm due to non-obstructive azoospermia in the male partner, transfer of an embryo with a reported intermediate chromosome copy number (i.e. mosaic), preimplantation genetic testing cycles for monogenic disorders, or structural chromosome rearrangements were excluded. Ovarian stimulation protocols and embryology laboratory procedures including trophectoderm biopsy followed the usual practice of each center. The ploidy status of blastocysts was determined with comprehensive chromosome screening. Endometrial preparation protocols followed the usual practice of participating centers and included programmed cycles, natural or modified natural cycles. A total of 105 (0.085% of the total population) patients met the criteria and underwent at least one additional euploid blastocyst transfer after failing to achieve a positive pregnancy test with three consecutive euploid blastocyst transfers. Outcomes of the fourth and fifth euploid blastocyst transfers were similar across participating centers. Overall, the live birth rate was similar with the fourth and fifth euploid blastocysts (40% vs 53.3%, relative risk = 1.33, 95% CI = 0.93-1.9, P value = 0.14). Sensitivity analyses excluding blastocysts biopsied on Day 7 postfertilization, women with a BMI >30 kg/m2, cycles using non-ejaculate or donor sperm, double-embryo transfer cycles, and cycles in which the day of embryo transfer was modified due to endometrial receptivity assay test result yielded similar results. Where data were available, the fourth euploid blastocyst had similar live birth rate with the first one (relative risk = 0.84, 95% CI = 0.58-1.21, P = 0.29). The cumulative live birth rate after five euploid blastocyst transfers was 98.1% (95% CI = 96.5-99.6%). Retrospective design has its own inherent limitations. Patients continuing with a further euploid embryo transfer and patients dropping out from treatment after three failed euploid transfers can be systematically different, perhaps with regard to ovarian reserve or economic status. Implantation failure seems to be mainly due to embryonic factors. Given the stable and high live birth rates up to five euploid blastocysts, unexplained recurrent implantation failure should have a prevalence of <2%. Proceeding with another embryo transfer can be the best next step once a known etiology for implantation failure is ruled out. None. N/A.

Intravenous immunoglobulin for patients with unexplained recurrent implantation failure: a 6-year single center retrospective review of clinical outcomes

The effectiveness of intravenous immunoglobulin (IVIg) for patients with unexplained recurrent implantation failure (uRIF) remains debated. We retrospectively analysed outcomes of uRIF patients treated with IVIg compared to a separate control uRIF cohort within our center (01/2014–12/2021). Primary outcomes included live birth, miscarriage, or transfer failure. We documented IVIg side effects and maternal/fetal outcomes. Logistic regression analysis was used to assess for association of IVIg exposure with outcomes and adjust for confounders. The study included 143 patients, with a 2:1 ratio of controls to patients receiving IVIg treatment. Patient characteristics were similar between groups. There was higher live birth rate (LBR) in patients receiving IVIg (32/49; 65.3%) compared to controls (32/94; 34%); p < 0.001). When stratifying patients into moderate and severe uRIF (respectively 3–4 and ≥\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\ge$$\\end{document} 5 previous good quality blastocyst transfer failures), only patients with severe uRIF benefited from IVIg (LBR (20/29 (69%) versus 5/25 (20%) for controls, p = 0.0004). In the logistic regression analysis, IVIg was associated with higher odds of live birth (OR 3.64; 95% CI 1.78–7.67; p = 0.0004). There were no serious adverse events with IVIg. IVIg can be considered in well selected patients with ≥\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\ge$$\\end{document} 5 previous unexplained, high quality blastocyst transfer failures. A randomized controlled trial is needed to confirm these findings.

Centromeric AA motif in KIR as an optimal surrogate marker for precision definition of alloimmune reproductive failure

Throughout pregnancy, the decidua is predominantly populated by NK lymphocytes expressing Killer immunoglobulin-like receptors (KIR) that recognize human leukocyte antigen-C (HLA-C) ligands from trophoblast cells. This study aims to investigate the association of KIR-HLA-C phenotypes in couples facing infertility, particularly recurrent pregnancy loss (RPL) and recurrent implantation failure (RIF), in comparison to a reference population and fertile controls. This observational, non-interventional retrospective case–control study included patients consecutively referred to our Reproductive Immunology Unit from 2015 to 2019. We analyzed the frequencies of KIR and HLA-C genes. As control groups, we analyzed a reference Spanish population for KIR analysis and 29 fertile controls and their male partners for KIR and HLA-C combinations. We studied 397 consecutively referred women with infertility and their male partners. Among women with unexplained RPL (133 women) and RIF (176 women), the centromeric (cen)AA KIR genotype was significantly more prevalent compared to the reference Spanish population (p = 0.001 and 0.02, respectively). Furthermore, cenAA was associated with a 1.51-fold risk of RPL and a 1.2-fold risk of RIF. Conversely, the presence of BB KIR showed a lower risk of reproductive failure compared to non-BB KIR (OR: 0.12, p < 0.001). Women and their partners with HLA-C1C1/C1C1 were significantly less common in the RPL-Group (p < 0.001) and RIF-Group (p = 0.002) compared to the control group. Moreover, the combination of cenAA/C1C1 in women with C1C1 partners was significantly higher in the control group than in the RPL (p = 0.009) and RIF (p = 0.04) groups, associated with a 5-fold increase in successful pregnancy outcomes. In our cohort, the cenAA KIR haplotype proved to be a more accurate biomarker than the classic AA KIR haplotype for assessing the risk of RPL and RIF, and might be particularly useful to identify women at increased risk among the heterogeneous KIR AB or Bx population. The classification of centromeric KIR haplotypes outperforms classical KIR haplotypes, making it a better indicator of potential maternal–fetal KIR-HLA-C mismatch in patients.

Preimplantation Genetic Testing for Aneuploidy Could Not Improve Cumulative Live Birth Rate Among 705 Couples with Unexplained Recurrent Implantation Failure.

We evaluate whether next-generation sequencing (NGS)-based preimplantation genetic testing for aneuploidy (PGT-A) improves the cumulative pregnancy outcomes of patients with unexplained recurrent implantation failure (uRIF) as compared to conventional in vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI). This was a retrospective cohort study (2015-2022). A total of 705 couples diagnosed with uRIF were included in the study. 229 women transferred blastocysts based on morphological grading (IVF/ICSI) and 476 couples opted for PGT-A to screen blastocysts by NGS. Women were further stratified according to age at retrieval (<38 years and ≥38 years). The primary outcome was the cumulative live-birth rate after all the embryos were transferred in a single oocyte retrieval or until achieving a live birth. Confounders were adjusted using binary logistic regression models. Cumulative live-birth rate was similar between the IVF/ICSI group and the PGT-A group after stratified by age: IVF/ICSI vs PGT-A in the <38 years subgroup (49.7% vs 57.7%, adjusted OR (95% CI) = 1.25 (0.84-1.84), P = 0.270) and in the ≥38 years subgroup (14.0% vs 19.5%, adjusted OR (95% CI) = 1.09 (0.41-2.92), P = 0.866), respectively. Nonetheless, the PGT group had a lower first-time biochemical pregnancy loss rate (17.0% vs 8.7%, P = 0.034) and a higher cumulative good birth outcome rate (35.2% vs 46.4%, P = 0.014) than the IVF/ICSI group in the <38 years subgroup. Other pregnancy outcomes after the initial embryo transfer and multiple transfers following a single oocyte retrieval were all similar between groups. Our results showed no evidence of favorable effects of PGT-A treatment on improving the cumulative live birth rate in uRIF couples regardless of maternal age. Use of PGT-A in the <38 years uRIF patients would help to decrease the first-time biochemical pregnancy loss and increase the cumulative good birth outcome.

Role of Platelet-rich Plasma in Unexplained Recurrent Implantation Failure - A Systematic Review and Meta-analysis of Randomised Control Trials.

Recurrent implantation failure (RIF) is a challenging clinical situation and various strategies have been tried to improve the pregnancy rate in RIF. Platelet-rich plasma (PRP), which is obtained from the autologous blood samples of a person and is multiple times richer in platelets and other growth factors helps improve endometrial receptivity. This study has been conducted to summarise the evidence and quality of evidence available so far regarding the role of PRP in cases of unexplained RIF. An electronic database search for randomised clinical trials comparing PRP against routine care in women with unexplained RIF was performed on PubMed, EMBASE, SCOPUS and Cochrane Central. Two independent reviewers conducted a literature search and retrieved data using the predefined eligibility criteria. Bias assessment was done using the Cochrane Collaboration Network Risk of Bias Tool version 2. The quality of evidence was determined and a summary of the findings table was prepared for individual outcomes using GRADEpro software. We identified 1146 records, and after removing duplicates, 531 records were screened. Out of these, 22 studies reached full-text screening and nine studies were included in the final review. We are uncertain about the effect of PRP due to the very low quality of evidence and we have little confidence that the administration of PRP had any significant effect on improving the live birth rate in women with RIF (odds ratio [OR]: 7.32, 95% confidence interval [CI]: 4.54-11.81, I2 = 40%). Similarly, the quality of evidence was low for the clinical pregnancy rate, so we are uncertain if the administration of PRP had any significant effect on the clinical pregnancy rate (OR: 3.20, 95% CI: 2.38-4.28, I2 = 0%). The current review suggests that there may be some beneficial effects of PRP in women with RIF, but the quality of evidence is very low and we are uncertain of the benefit and have little confidence in these findings. Limitations are the small sample size of most studies, a short follow-up period, non-uniformity in the definition of outcomes and very low quality of evidence. The protocol was registered on PROSPERO (CRD42021292209).

#248 : Maternal Hypercholesterolemia Would Increase the Incidence of Embryo Aneuploidy in Couples with Recurrent Implantation Failure

Background and Aims: The association of dyslipidemia with reproductive outcomes is largely unknown, especially in recurrent implantation failure (RIF) patients. This study aimed to explore the impact of abnormal blood lipid levels on embryo genetic status and pregnancy outcomes in unexplained RIF (uRIF) patients after preimplantation genetic testing for aneuploidy (PGT-A). Method: In this retrospective study, they were divided into 4 groups according to the levels of cholesterol and triglyceride: non-hyperlipidemia group (NonH group), simple hypercholesterolemia group (SHC group), simple hypertriglyceridemia group (SHC group) and mixed hyperlipidemia group (MixH group). Additionally, patients were divided into 2 groups according to their HDL-C level. Embryos’ genetic status and pregnancy outcomes after transfer of euploid embryos were analyzed. Binary logistic regression and/or generalized estimating equation model were conducted to investigate the association of different types of dyslipidemia with aneuploid embryo rate and cumulative live-birth rate. Results: A total of 474 women were divided into four groups: NonH group (N=349), SHC group (N=55), SHT group (N=52) and MixH group (N=18). Compared with the NonH group, SHC group had a significantly increased aneuploid embryo rate [48.3% vs. 36.7%, P=0.006; adjusted OR (95% CI) = 1.52(1.04-2.22)], as well as a reduced number of good-quality blastocysts [3.00±2.29 vs. 3.74±2.77, P=0.033]. The SHC group showed a lower cumulative live-birth rate (47.0% vs. 40.0%), good birth outcome (37.2% vs. 34.5%) and a higher risk of clinical pregnancy loss (11.1% vs. 17.9%) but did not reach statistical significance. The incidences of obstetric or neonatal complications and other adverse events were similar in the four groups. Conclusion: We found that uRIF women with hypercholesterolemia had an increased proportion of aneuploid embryos and a reduced number of high-quality embryos, while different types of hyperlipidemias had no correlation with cumulative live birth rate as well as pregnancy and neonatal outcomes.

Establishment of Cut-off Values for Uterine and Peripheral Blood Natural Killer Cells During the Peri-implantation Period in Fertile Controls and Women with Unexplained Recurrent Implantation Failure.

The purpose of the study was to determine the cut-off values for peripheral and uterine natural killer (pNK, uNK) cells in fertile controls and in women with recurrent implantation failure (RIF). In this study, 50 women with RIF and 50 fertile controls were enrolled. Midluteal endometrial biopsy samples from both cases and controls were obtained for CD 56+ cell immunohistochemistry labeling to identify uNK cells. Peripheral venous blood was also taken during the biopsy to detect pNK cells in peripheral blood mononuclear cells using flow cytometry. Cut-off values were obtained from fertile controls. Using a non-parametric Mann-Whitney U-test, the medians of the data sets were compared. The median values for uNK and pNK cell levels in the control group were 7% and 11.6%, respectively. The median value for uNK cells in RIF patients was 9%, which was higher than the one in controls but not statistically significant (p-value of 0.689). The median pNK levels (11.6% vs. 12.4%) were comparable between the RIF group and the controls. Moreover, it was found that 68% of individuals had uNK cell counts below the reference value, while 32% had excessive levels exceeding 7%. Additionally, only 51.4% of the RIF group had increased pNK cells. The pNK cell cut-off values need to be used with caution because there was no difference between fertile controls and RIF women. If immunotherapy is recommended for RIF women, uNK cell testing should be used as the preferred approach.

Maternal hypercholesterolemia would increase the incidence of embryo aneuploidy in couples with recurrent implantation failure

BackgroundThe association of dyslipidemia with embryo development and pregnancy outcomes is largely unknown, especially in unexplained recurrent implantation failure (uRIF) patients. Here, this study aimed to explore the impact of abnormal blood lipid levels on embryo genetic status and pregnancy outcomes after preimplantation genetic testing for aneuploidy (PGT-A) from a clinical perspective.MethodsThis study retrospectively analyzed 502 patients diagnosed as uRIF. They were divided into four groups according to the levels of cholesterol and triglyceride: nonhyperlipidemia group (NonH group), simple hypercholesterolemia group (SHC group), simple hypertriglyceridemia group (SHC group) and mixed hyperlipidemia group (MixH group). At the same time, patients were divided into non-low HDL-C group and low HDL-C group according to their HDL-C level. The outcomes of embryos genetic testing and pregnancy outcomes after PGT-A was analyzed between groups. Binary logistic regression and/or generalized estimating equation (GEE) model were conducted to investigate the association of different types of dyslipidemia with embryonic aneuploidy rate and cumulative live-birth rate.Results474 women who met the inclusion criteria were divided into four groups: NonH group (N = 349), SHC group (N = 55), SHT group (N = 52) and MixH group (N = 18). Compared with the NonH group, SHC group had a significantly increased rate of embryo aneuploidy [48.3% vs. 36.7%, P = 0.006; adjusted OR (95% confidence interval) = 1.52(1.04–2.22), P = 0.029], as well as a reduced number of good-quality embryos on day 5 or 6 [3.00 ± 2.29 vs. 3.74 ± 2.77, P = 0.033]. The SHC group showed a tendency of a lower cumulative live birth rate (47.0% vs. 40.0%), a lower incidence of good birth outcome (37.2% vs. 34.5%) and a higher risk of clinical pregnancy loss (11.1% vs. 17.9%), but did not reach statistical significance (P > 0.05). The incidences of obstetric or neonatal complications and other adverse events were similar in the four groups. Whether patients have low HDL-C did not differ in pregnancy outcomes.ConclusionsWe found that uRIF women with hypercholesterolemia had an increased proportion of aneuploid embryos and a reduced proportion of high-quality embryos, while different types of hyperlipidemia had no correlation with cumulative live birth rate as well as pregnancy and neonatal outcomes.

Impact of intrauterine injection of human chorionic gonadotropin Vs intrauterine infusion of autologous platelet rich plasma Vs endometrial scratch on pregnancy rates as management of unexplained recurrent implantation failure (A prospective comparative study)

Impact of intrauterine injection of human chorionic gonadotropin Vs intrauterine infusion of autologous platelet rich plasma Vs endometrial scratch on pregnancy rates as management of unexplained recurrent implantation failure (A prospective comparative study)

Immune profiling and RNA-seq uncover the cause of partial unexplained recurrent implantation failure.

Detailed knowledge of the changes in endometrial immune cells during the window of implantation in unexplained recurrent implantation failure (RIF) patients, the functions performed by immune cells, and the interactions between them is largely lacking. This study aimed to classify RIF patients and explore the mechanism through endometrial immune profiling and RNA-seq analysis. This study enrolled a total of 172 patients, comprising 144 women with unexplained RIF and 28 fertile women. Endometrial samples were collected using endometrial scratching at the mid-luteal phase before in vitro fertilization treatment or pregnancy. Transcriptome sequencing and immunohistochemical staining of endometrial immune cells including natural killer (NK) cells, macrophages, T cells, and B cells were performed. Comparison of the percentage of endometrial immune cells and the RNA-seq information between RIF patients and fertile control patients. The proportions of uterine CD56+ uNK cells, CD57+ NKT cells, CD68+ macrophages, and CD19+ B cells were significantly elevated in RIF patients. In addition, the number of positive CD68 glandular lumens was significantly higher in RIF patients than in the fertile group. In addition, based on this result, we classified RIF patients into three categories. Hyperactivation of endometrial immune cells may be associated with reduced endometrial tolerance and recurrent implantation failure, affecting pregnancy outcomes in RIF patients.

Association of embryo aneuploidy and sperm DNA damage in unexplained recurrent implantation failure patients under NGS-based PGT-A cycles.

Recurrent implantation failure (RIF) is one of the most common conditions affecting In Vitro Fertilization (IVF)/Intracytoplasmic sperm injection (ICSI) outcomes. Aneuploidy embryos, one of the main types of embryos-related factors, was reported to be a major contributor to RIF. The present study aimed to examine the association between sperm DNA fragmentation index (DFI) and outcomes of next-generation sequencing (NGS)-based preimplantation genetic testing for aneuploidy (PGT-A) in unexplained RIF patients. This study analyzed 119 couples with unexplained RIF who underwent 119 PGT-A cycles between January, 2017 and March, 2022. The 119 males were divided into 3 groups according to their sperm DFI levels: Group1 (low, DFI ≤ 15%, n = 50), Group2 (medium, 15% < DFI < 30%, n = 41) and Group3 (high, DFI ≥ 30%, n = 28). Sperm DFI was measured by sperm chromatin structure analysis (SCSA) technique. Trophectoderm biopsy on day 5 or 6 were performed with NGS technique. The following outcomes of PGT-A were analyzed and compared: fertilization, good-quality embryos, aneuploidy rate, miscarriage, live birth and newborn defects. The component of aneuploidy embryos was significantly higher in high DFI group (42.71%) than that of medium group (28.39%) and low group (27.80%). The miscarriage rate of high DFI group (27.27%) and medium group (14.29%) is significantly higher than that of low group (0.00%). No significant differences were found regarding fertility, good-quality embryo rate, pregnancy rate, live birth rate or newborn defects among three groups. The sperm DNA damage is associated with blastocyst aneuploidy and miscarriage rate in unexplained RIF cases. Embryo selection by PGT-A and efforts to decrease sperm DFI before IVF/ICSI treatments should be considered for those male patients with high DFI.

Preimplantation genetic testing for aneuploidy helps to achieve a live birth with fewer transfer cycles for the blastocyst FET patients with unexplained recurrent implantation failure.

This retrospective cohort study aimed to investigate the value of preimplantation genetic testing for aneuploidy (PGT-A) as a screening test for patients suffering from unexplained recurrent implantation failure (RIF). After screening patients in one reproductive medicine center, twenty-nine, forty-nine and thirty-eight women (< 40years old) who had suffered unexplained RIF with PGT-A, or RIF without PGT-A, or no RIF with PGT-A were included. The clinical pregnancy rate and live birth rate per transfer, the conservative and optimal cumulative clinical pregnancy rates (CCPR) and live birth rates (CLBR) after three blastocyst FETs were analyzed. The live birth rate per transfer was significantly higher in the RIF + PGT-A group than that in the RIF + NO PGT-A group (47.6% vs. 24.6%, p = 0.014). After 3 cycles of FET, RIF + PGT-A group had significantly higher conservative CLBR and optimal CLBR compared to the RIF + NO PGT-A group (69.0% vs. 32.7%, p = 0.002 and 73.7% vs. 57.5%, p = 0.016), but had similar conservative and optimal CLBRs compared to the NO RIF + PGT-A group. The number of FET cycles required when half women achieved a live birth was 1 in the PGT-A group and 3 in RIF + NO PGT-A group. The miscarriage rates werenot different between the RIF + PGT-A and RIF + NO PGT-A, RIF + PGT-A and NO RIF + PGT-A groups. PGT-A did be superior in reducing the number of transfer cycles required to achieve a similar live birth rate. Further studies to identify the RIF patients who would benefit most from PGT-A are necessary.

Effect of low-molecular-weight heparin in women undergoing frozen-thawed embryo transfer cycles: a retrospective cohort study

BackgroundRecurrent pregnancy loss (RPL) and recurrent implantation failure (RIF) during in vitro fertilization (IVF) treatment are still tough problems without effective treatments; thus, they are important research topics. There is controversy on whether low molecular weight heparin (LMWH) improves pregnancy outcomes in women with unexplained RPL and RIF. Moreover, currently, there is a paucity of reports on the role of LMWH in the entire population undergoing frozen-thawed embryo transfer (FET) cycles. This study aimed to estimate the effects of LMWH on pregnancy outcomes in women undergoing FET cycles.MethodsThere were 1881 female patients included in the study. Of the 1881 patients, 107 underwent preimplantation genetic diagnosis cycles, which were analyzed individually. The patients were divided into two groups: the LMWH group received injections of 4100 IU/d LMWH from the day of transfer until 14 ± 2 days posttransplant, the control group was the comparison group (without LMWH use). The baseline characteristics and reproductive outcomes of the patients were reviewed.ResultsOf the 1774 women with normal FET cycles, no significant differences were found in the number of embryos implanted (1.31 ± 0.02 vs. 1.28 ± 0.02), embryo implantation rate, biochemical pregnancy rate, clinical pregnancy rate, live birth rate, late abortion rate, and ectopic pregnancy rate between the two groups. The LMWH group had a higher early abortion (17.8% [76/427] vs. 12.5% [55/439], p = 0.030). In the sub-group analysis, among the patients who underwent more than four transfers, the LMWH group had a lower late abortion rate (1.7% [1/60] vs. 13.2% [7/53], p = 0.043). Similarly, of the 107 women who underwent preimplantation genetic diagnosis cycles, the reproductive outcomes were comparable between the two groups.ConclusionIn the general population and PGD patients, LMWH did not improve pregnancy outcomes. Therefore, the routine use of LMWH is not recommended for early treatment.

Characterization of epidermal growth factor-like domain 7 (EGFL7) expression in normal endometrium and in the endometrium of women with poor reproductive outcomes.

Could epidermal growth factor-like domain 7 (EGFL7) be a factor involved in the preparation of the endometrium for implantation and could its dysregulation be implicated in poor reproductive outcomes? EGFL7 is highly expressed in the endothelium and glandular epithelium throughout the menstrual cycle; it is upregulated by stromal cells in secretory phase and appears strongly reduced in endometrial biopsies and isolated stromal cells of women with unexplained recurrent pregnancy loss (uRPL) and recurrent implantation failure (RIF). The secreted factor EGFL7, originally identified as a gene primarily expressed in endothelial cells, is also expressed by the mouse blastocyst and by mouse and human trophoblast cells. It regulates trophoblast migration and invasion by activating NOTCH1 signaling. NOTCH1 has been demonstrated to play a fundamental role in endometrial receptivity and its dysregulation may be involved in selected pregnancy complications characterized by altered endometrial receptivity, such as uRPL. This is an exploratory study for which 84 endometrial biopsies were collected from normally fertile women, as well as from women with uRPL and RIF. Samples were collected from women in both the proliferative and secretory phases of the menstrual cycle and stratified into three sub-groups according to the patient clinical history: 20 fertile women (8 in proliferative and 12 in secretory phase), 41 women with uRPL (6 in proliferative and 35 in secretory phase), and 27 women with RIF (8 in proliferative and 19 in secretory phase). Immunohistochemistry, real-time PCR, and western blot analyses were performed to study the expression of EGFL7 and NOTCH1, as well as the NOTCH target genes. Analysis of spatial and temporal distribution of EGFL7 in endometrial biopsies from fertile women revealed higher levels of EGFL7 in samples from the secretory phase compared to proliferative phase. The expected expression of EGFL7 in endothelial cells was shown as well as the novel, not previously reported, expression in endometrial glands and stromal cells. EGFL7 was significantly reduced in the endometrium of women with uRPL and RIF in the secretory phases and this was associated with a downregulation of the NOTCH1 signaling pathway. Human recombinant EGFL7 was able to activate the NOTCH1 signaling pathway in endometrial stromal cells (EndSCs) obtained from fertile women but not in cells from uRPL or RIF patients. EndSCs from fertile women and decidualized in vitro for three days showed an upregulation of EGFL7 expression, whereas cells obtained from women with uRPL and RIF and decidualized in vitro did not. This study was conducted with a relatively small number of patient samples. Although results are highly reproducible and consistent, additional observations from multicentric cohorts would strengthen the relevance of the data. Moreover, this is an in vitro study, which might only partially represent the in vivo conditions. Our results demonstrate for the first time that EGFL7 is new player involved in decidualization and provide new insights into the pathophysiology of selected implantation defects and early pregnancy complications. Our studies have revealed that alterations in EGFL7 expression and the consequent dysregulation of NOTCH signaling are potential underlying causes of RIF and uRPL. Our results might have therapeutic relevance, as the EGFL7/NOTCH pathway may represent a potential target for medical intervention. This study has been supported by the Grant for Fertility Innovation 2017 (Merck KGaA). There are no competing interests to disclose. Not applicable.

Predictive value of D-dimer in patients with unexplained recurrent implantation failure during freeze-thaw embryo transfer cycles.

This study aimed to evaluate whether D-dimer can predict the clinical outcomes of patients with unexplained recurrent implantation failure (URIF) during freeze-thaw embryo transfer (FET) cycles. Our study was divided into two parts. The first part was a retrospective study that included 433 patients. Plasma D-dimer levels were monitored in all patients before FET, and the patients were classified into two groups according to whether they delivered at least one live infant or not. D-dimer was compared between groups, and receiver operating characteristic (ROC) curves were constructed to analyze the impact of D-dimer on live birth. The second part was a prospective study that included 113 patients who were categorized into high and low D-dimer groups based on the ROC curve analysis from the retrospective study. Clinical outcomes were compared between these two groups. In the first part, we found that plasma D-dimer levels in patients with live birth were significantly lower than those in patients without live birth. According to the ROC curve, 0.22mg/L was the cutoff value for D-dimer in the prediction of the live birth rate (LBR) (AUC 0.806, 95% CI: 0.763, 0.848). The second part of the study confirmed that clinical pregnancy rate (50.98%vs. 32.26%, P=.044) and LBR (41.18%vs. 22.58%, P=.033) of patients with D-dimer ≤0.22mg/L were all significantly higher than those of patients with D-dimer>0.22mg/L. Our study indicates that D-dimer>0.22mg/L is a useful index for predicting URIF during FET cycles.

Potential Biomarkers and Endometrial Immune Microenvironment in Recurrent Implantation Failure

The molecular mechanisms underlying unexplained recurrent implantation failure (RIF) remain unclear. This study aimed at identifying potential biomarkers, exploring relevant signaling pathways, and analyzing the contribution of immune cell infiltration in RIF. Microarray expression datasets were extracted from the Gene Expression Omnibus database to perform bioinformatic analyses. The results showed that ten hub genes may predict RIF with high specificity and sensitivity (area under the curve = 1.000). Protein-protein interaction analysis revealed close interactions between the hub genes and the endometrial receptivity array. The real-time quantitative polymerase chain reaction further validated three potential biomarkers (RAB32, TRIB2, and FAM155B). Functional enrichment analyses indicated that immune pathways were significantly downregulated and lipid metabolism pathways were significantly upregulated in RIF compared with the controls. Significant negative correlations were observed between fatty acid biosynthesis and the immune pathways. Immune cell infiltration, including those in CD56dim natural killer, dendritic, Th1, Th2, and regulatory T cells, as well as macrophages, was significantly reduced in RIF compared with the controls used herein. This study may provide a novel perspective on the diagnosis and treatment of RIF.

Immunomodulation for unexplained recurrent implantation failure: where are we now?

Immune dysfunction may contribute to or cause recurrent implantation failure. This article summarizes normal and pathologic immune responses at implantation and critically appraises currently used immunomodulatory therapies. Recurrent implantation failure (RIF) may be defined as the absence of pregnancy despite the transfer of ≥3 good-quality blastocysts and is unexplained in up to 50% of cases. There are currently no effective treatments for patients with unexplained RIF. Since the maternal immune system is intricately involved in mediating endometrial receptivity and embryo implantation, both insufficient and excessive endometrial inflammatory responses during the window of implantation are proposed to lead to implantation failure. Recent strategies to improve conception rates in RIF patients have focused on modulating maternal immune responses at implantation, through either promoting or suppressing inflammation. Unfortunately, there are no validated, readily available diagnostic tests to confirm immune-mediated RIF. As such, immune therapies are often started empirically without robust evidence as to their efficacy. Like other chronic diseases, patient selection for immunomodulatory therapy is crucial, and personalized medicine for RIF patients is emerging. As the literature on the subject is heterogenous and rapidly evolving, we aim to summarize the potential efficacy, mechanisms of actions and side effects of select therapies for the practicing clinician.

Clinical Applications of Recombinant Human Granulocyte Colony-Stimulating Factor in Reproductive Medicine: Expert Consensus

The primary clinical indication for recombinant human granulocyte-stimulating factor (rhG-CSF) is neutropenia of multiple etiologies. In recent years, rhG-CSF has been proved to be effective and safe for mothers and fetus in the clinical application in some reproductive disorders. Until recently, there has been no reliable evidence of authoritative expert consensus or standards. In order to regulate the research and rational application of rhG-CSF in the fields of reproductive medicine, the Committee on Reproductive Immunity of the China Society for the Promotion of Human Health Science and Technology (the Committee) organized experts from relevant disciplines to formulate the Expert Consensus, which is based on the latest international basic study and clinical research evidence. According to evidence-based data, recommendations were established on the applicable population, starting method, and duration of rhG-CSF administration in reproductive medicine. It is recommended that rhG-CSF could be applicated in the patients with thin endometrium which was ineffective to standard treatments, in unexplained recurrent spontaneous abortion (RSA), in unexplained recurrent implantation failure (RIF), and could attempt to be applicated in unexplained RSA with slow rise of human chorionic gonadotropin and/or embryo growth retardation. Meanwhile, the patients are demand of ineffective to the standard therapy and need to sign informed consent for the off-label use of rhG-CSF before treatment. Comprehensive communication between OB/GYN and patients before therapy is essential according to that the rhG-CSF treatment would be inefficient when genetic abnormality, gamete damage, heterotopic pregnancy and other unknown disorder exist.

An IGF1-expressing endometrial stromal cell population is associated with human decidualization

Decidualization refers to the process of transformation of endometrial stromal fibroblast cells into specialized decidual stromal cells that provide a nutritive and immunoprivileged matrix essential for blastocyst implantation and placental development. Deficiencies in decidualization are associated with a variety of pregnancy disorders, including female infertility, recurrent implantation failure (RIF), and miscarriages. Despite the increasing number of genes reportedly associated with endometrial receptivity and decidualization, the cellular and molecular mechanisms triggering and underlying decidualization remain largely unknown. Here, we analyze single-cell transcriptional profiles of endometrial cells during the window of implantation and decidual cells of early pregnancy, to gains insights on the process of decidualization. We observed a unique IGF1+ stromal cell that may initiate decidualization by single-cell RNA sequencing. We found the IL1B+ stromal cells promote gland degeneration and decidua hemostasis. We defined a subset of NK cells for accelerating decidualization and extravillous trophoblast (EVT) invasion by AREG-IGF1 and AREG-CSF1 regulatory axe. Further analysis indicates that EVT promote decidualization possibly by multiply pathways. Additionally, a systematic repository of cell-cell communication for decidualization was developed. An aberrant ratio conversion of IGF1+ stromal cells to IGF1R+ stromal cells is observed in unexplained RIF patients. Overall, a unique subpopulation of IGF1+ stromal cell is involved in initiating decidualization. Our observations provide deeper insights into the molecular and cellular characterizations of decidualization, and a platform for further development of evaluation of decidualization degree and treatment for decidualization disorder-related diseases.

A new enrichment approach for candidate gene detection in unexplained recurrent pregnancy loss and implantation failure.

Recurrent pregnancy loss (RPL) and implantation failure (RIF) are obstacles to livebirth and multifactorial conditions in which nearly half of the cases remain unexplained, and we aimed to identify maternal candidate gene variants and pathways for RPL and RIF by analyzing whole-exome sequencing (WES) data via a new detailed bioinformatics approach. A retrospective cohort study was applied to 35 women with normal chromosomal configuration diagnosed with unexplained RPL and/or RIF. WES and comprehensive bioinformatics analyses were performed. Published gene expression datasets (n = 46) were investigated for candidate genes. Variant effects on protein structure were analyzed for 12 proteins, and BUB1B was visualized in silico. WES and bioinformatics analyses are effective and applicable for studying URPL and RIF to detect mutations, as we suggest new candidates to explain the etiology. Forty-three variants in 39 genes were detected in 29 women, 7 of them contributing to oligogenic inheritance. These genes were related to implantation, placentation, coagulation, metabolism, immune system, embryological development, cell cycle-associated processes, and ovarian functions. WES, genomic variant analyses, expression data, and protein configuration studies offer new and promising ways to investigate the etiology of URPL and RIF. Discovering etiology-identifying genetic factors can help manage couples' needs and develop personalized therapies and new pharmaceutical products in the future. The classical approach with chromosomal analysis and targeted gene panel testing is insufficient in these cases; the exome data provide a promising way to detect and understand the possible clinical effects of the variant and its alteration on protein structure.