Recurrent implantation failure: definition and management

Understanding epigenetic regulation in the endometrium - lessons from mouse models with implantation defects

Endometrial function, crucial for successful embryo implantation, is significantly influenced by epigenetic regulation. This review investigates the crucial roles of DNA methylation, histone modifications, chromatin remodeling, and RNA methylation in endometrial receptivity and implantation, based on a survey of recent literature on knockout mouse models with implantation defects. These models illuminate how epigenetic disruptions contribute to implantation failure, a significant human reproductive health concern. DNA methylation and histone modifications modulate endometrial receptivity by affecting gene silencing and chromatin structure, respectively. Chromatin remodeling factors also play a critical role in endometrial dynamics, influencing gene expression. Furthermore, RNA methylation emerges as critical in implantation through transcriptional and translational control. While human studies provide limited epigenetic snapshots, mouse models with suppressed epigenetic regulators reveal direct causal links between epigenetic alterations and implantation failure. Understanding these epigenetic interactions offers potential for novel therapies addressing reproductive disorders.

Live birth rate and perinatal outcomes following sequential embryo transfer in women with recurrent implantation failure undergoing frozen-thawed embryo transfer cycles

BACKGROUND

Sequential embryo transfer (ET) has been used to improve clinical outcomes in patients with recurrent implantation failure (RIF). This study aimed to evaluate whether sequential ET influence the live birth rate and perinatal outcomes of women with RIF.

METHODS

A cohort study of RIF patients who underwent sequential ET (Seq-ET) during frozen-thawed embryo transfer (FET) cycles between January 2020 and June 2023 was performed. FET patients who underwent double cleavage-stage ET (D3-dET) and double blastocyst ET (D5/6-dET) during the same period composed the control group. The live birth rate and perinatal outcomes of the groups were analyzed and compared.

RESULTS

The Seq-ET group had a significantly greater live birth rate (42.9%) than the D3-dET group (33.1%), and the live birth rate of the Seq-ET group was comparable to that of the D5/6-dET group (35.7%). Female BMI (aOR 0.96, 95%CI 0.92-1.00), stimulation for endometrial preparation (aOR 0.47, 95%CI 0.26-0.84), and endometrial thickness (aOR 1.08, 95%CI 1.00-1.16) were contributing factors to the live birth rate. No statistically significant differences were found in the rate of healthy birth or twins among the Seq-ET, D3-dET and D5/6-dET groups. There was no statistically significant difference in the rates of preterm delivery, birth weight or length, low birthweight, macrosomia, small for gestational age (SGA), gestational diabetes mellitus (GDM), gestational hypertensive disease (GHD), or the sex ratio among the three groups. The infants born in D5/6-dET group had less gestational weeks than in the Seq-ET and D3-dET groups (38.05 ± 1.88 vs. 38.43 ± 2.09 and 38.45 ± 1.80, P = 0. 013) and had a higher risk of large for gestational age (LGA) (aOR 2.15, 95%CI 1.00-4.62) compared to infants born in the D3-dET group.

CONCLUSION

The live birth rate was significantly higher in the Seq-ET group compared with the D3-dET group, and slightly higher compared to the D5/6-dET group. Our results suggested sequential ET did not affect the perinatal outcomes.

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.

Effect of Comprehensive Individualised Interventions on the Clinical Outcomes of Patients With Recurrent Implantation Failure: A Single-Centre Retrospective Cohort Study

OBJECTIVE

The objective of this study is to evaluate the impact of comprehensive individualised interventions on the clinical outcomes of patients with recurrent implantation failure (RIF), as few studies have evaluated their effectiveness.

DESIGN

Retrospective cohort study.

SETTING

Tertiary hospital, from June 2016 to December 2022.

POPULATION

Overall, 1546 patients with RIF underwent endometrial biopsy during implantation.

METHODS

The comprehensive individualised interventions were conducted on the basis of the endometrial histological dating, endometrial CD138 count, endometrial immune-cell proportion and endometrial microbiota testing.

MAIN OUTCOME MEASURES

Cumulative ongoing pregnancy rate (cOPR).

RESULTS

The median number of failed transfer cycles was 3 (range, 2-12), and the cOPR was 58.0%. The rates of window of implantation (WOI) displacement, CD138 positivity, imbalanced endometrial immune-cell proportion, endometrial microbiota testing, multiple factors and unexplained RIF were 34.0%, 9.3%, 7.5%, 4.1%, 32.4% and 12.7%, respectively. The cOPRs of the individualised frozen embryo transfers in patients having RIF with WOI displacement, WOI CD138 positivity, imbalanced endometrial immune-cell proportion, endometrial microbiota testing, multiple factors and unexplained RIF were 64.1%, 57.6%, 55.1%, 38%, 64.2% and 34.5%, respectively. After adjusting for basic characteristics through logistic regression analysis, the cOPRs of the WOI displacement group, WOI CD138 positive group and immune-cell proportion imbalanced group remained higher than that of the unexplained RIF group. However, the cOPR was comparable between the endometrial microbiota testing and unexplained RIF groups.

CONCLUSION

Comprehensive individualised interventions may improve clinical outcomes for patients with RIF, warranting further investigation.

Measurement of four novel endometrial NK cell subsets by multiplex staining in women with reproductive failure: A comparison with fertile controls

Accumulating evidence indicates a significant increase in CD56 + endometrial NK cells in women with reproductive failure. However, CD56 alone inadequately captures the phenotypic and functional heterogeneity of these cells. This study aims to compare the density of various endometrial NK subsets between women with reproductive failure and healthy controls, as well as evaluate their diagnostic performance. This study included three groups: recurrent miscarriage (RM), repeated implantation failure (RIF), and controls, with 56 women in each group. Endometrial biopsy was performed precisely 7 days after LH surge or five days after the initiation of progesterone. Multiplex immunohistochemistry staining was employed to identify total CD56 +NK cells, classical NK subsets (CD56 +CD16 + and CD56 +CD16-), and four novel NK subsets: NK1-NK4. Using classical markers of NK cells, the density of CD56 +NK cells, as well as CD56 +CD16 + and CD56 +CD16- NK subsets, was significantly higher in women with RM or RIF compared to controls. When NK cells were further categorized into 4 subsets, only the immune-active NK2 and cytotoxic NK4 subsets showed a significant increase in women with RM or RIF groups. No significant differences were observed in the densities of NK1 and NK3. CD56 +CD16 + NK cells, NK2 and NK4 subsets demonstrated higher diagnostic accuracy over total CD56 + NK cells, as indicated by ROC analysis. In summary, this study reveals the specific differences in endometrial NK cell subsets in women with reproductive failure, suggesting that the elevated density of certain NK subsets in the endometrium is associated with an inflammatory microenvironment in women with reproductive failure.

Disruption of the Wnt/β-Catenin and PI3K-AKT-mTOR Crosstalk in Endometrial Stromal Cells: A Case Report of Impaired Decidualization Leading to Recurrent Implantation Failure and Potential Pathway-Specific Therapeutic Interventions

A 34-year-old woman with a long-standing history of recurrent implantation failure (RIF) and unexplained infertility presented for further evaluation. Molecular analysis revealed a significant disruption in the crosstalk between the Wnt/β-catenin and PI3K-AKT-mTOR signaling pathways, both essential for regulating endometrial receptivity and successful embryo implantation. Immunohistochemical testing showed a marked reduction in β-catenin nuclear translocation and a 65% decrease in AKT phosphorylation, leading to impaired cellular processes such as proliferation and differentiation. This disruption contributed to incomplete decidualization of the endometrium, which played a central role in her repeated implantation failures. Conventional fertility treatments, including hormone therapy and in vitro fertilization (IVF), were ineffective. Consequently, we explored targeted molecular therapies aimed at restoring functionality within these signaling pathways to enhance endometrial receptivity. This case underscores the critical role of the Wnt/β-catenin and PI3K-AKT-mTOR pathways in endometrial function and highlights the potential for novel therapeutic strategies in treating RIF by addressing specific molecular defects.

Effects of autologous platelet-rich plasma intrauterine perfusion on clinical outcomes in recurrent implantation failure patients with non-thin endometrium undergoing frozen-thawed embryo transfer

PURPOSE

To explore the effects of autologous platelet-rich plasma (PRP) intrauterine perfusion on clinical outcomes in recurrent implantation failure (RIF) patients with non-thin endometrium undergoing frozen-thawed embryo transfer (FET), and the effects of PRP used at different times before FET on clinical outcomes.

METHODS

A total of 160 RIF patients with non-thin endometrium undergoing FET were retrospectively analyzed. Among them, 82 patients received PRP intrauterine perfusion at 24-72 h before FET (PRP group), and 78 patients did not (non-PRP group). In PRP group, 59 patients underwent PRP at 24-48 h before FET (≥ 24 to  ≤ 48 h group), and 23 patients was at 48-72 h (> 48 to  ≤ 72 h group). The clinical outcomes were compared, including β-hCG positive rate, clinical pregnancy rate, embryo implantation rate, abortion rate, ectopic pregnancy rate, live birth rate and the incidence of adverse events.

RESULTS

The clinical pregnancy rate, embryo implantation rate and live birth rate in PRP group were significantly higher than those in non-PRP group (P < 0.05), and there were no statistical differences in β-hCG rate, abortion rate and ectopic pregnancy rate between the two groups (P > 0.05). Meanwhile, there was no adverse events occurred in PRP group. However, the C-type endometrium rate in PRP group was observably higher on FET day (Χ2 = 8.309, P = 0.004), though there was no statistical difference in endometrial thickness (P > 0.05). The multiple logistics regression analysis showed that PRP intrauterine perfusion are closely related with clinical pregnancy and live birth in RIF patients with non-thin endometrium (OR: 2.379, 95% CI 1.137-4.977, P = 0.021; OR: 2.107, 95% CI 1.006-4.412, P = 0.048). Moreover, we found no significant difference in clinical outcomes between the two groups of PRP intrauterine perfusion at ≥ 24 to ≤ 48 h and > 48 to ≤ 72 h before FET (P > 0.05), except for β-hCG positive rate.

CONCLUSIONS

PRP intrauterine perfusion can safely and effectively improve the clinical pregnancy rate, implantation rate and live birth rate in RIF patients with non-thin endometrium possibly by increasing the C-type endometrium rate on FET day. In addition, PRP intrauterine perfusion at different times of 24-72 h before FET does not affect the clinical outcomes, which will be helpful to guide clinical work flexibly.

Cell type and region-specific transcriptional changes in the endometrium of women with RIF identify potential treatment targets

Recurrent implantation failure (RIF) is a devastating condition that leaves many undergoing fertility treatment childless. The human endometrium is receptive to a blastocyst for a brief period, the window of implantation. Critical knowledge underpinning biological processes leading to RIF, essential for effective treatment, is lacking. We employed spatial transcriptomics to define region- and cell-type-specific differences in endometrial gene expression in luteinizing hormone timed biopsies between women with RIF (n = 8) and fertile controls (FC) (n = 8). Differentially expressed genes (DEGs) were identified when comparing endometrial regions between FC and RIF (685 luminal epithelium, 293 glandular epithelium, 419 subluminal stroma, 264 functionalis stroma, 1,125 subluminal stromal CD45+ leukocytes, and 1,049 functionalis stromal CD56+ leukocytes). Only 57 DEGs were common to all subregions and cell types, which highlights that multiple DEGs are lost when the endometrium is examined as a single entity. When RIF-specific DEGs were leveraged against knowledge from mouse genetic models, genes associated with aberrant embryo implantation phenotypes were observed, mostly in immune cell populations. Dysregulated pathways in specific endometrial regions included the "WNT signaling pathway," altered in the functionalis and subluminal stroma. "Response to estradiol" and "ovulation cycle" pathways were dysregulated in the subluminal stroma. In silico drug screening identified potential compounds that can reverse the RIF gene expression profile (e.g., raloxifene, bisoprolol). Our findings, in a well-characterized cohort, highly endorse consideration of each endometrial region and cell type as separate entities. Ignoring individual regions and composite cell populations will overlook important aberrations, forego potential treatment targets, and lead to research waste pursuing clinically irrelevant treatment options.

Is it justified to offer intrauterine infusion of autologous PRP in women with repeated implantation failure?

In recent years, an increased interest in the efficacy of intrauterine infusion of autologous platelet-rich plasma (PRP) in women with repeated implantation failure (RIF) has resulted in the publication of 13 randomized controlled trials (RCTs) and 11 meta-analyses. Although these meta-analyses support an increase in pregnancy rates after intrauterine infusion of autologous PRP, the low quality of the available original clinical studies along with concerns regarding their trustworthiness seriously questions their internal validity and does not allow for definitive conclusions to be drawn. In addition, the variability in the definition of RIF used in the individual studies limits their external validity, renders the pooling of the results problematic, and, overall, complicates the extrapolation of the results published. The variability in the definition of RIF has been recently addressed by the ESHRE, which published an evidence-based definition of RIF to facilitate the evaluation of interventions in these patients. Taking into consideration this definition, which identifies a real clinical problem, evaluation of intrauterine infusion of PRP in the published literature has not so far been performed explicitly in patients with RIF. The potential of intrauterine infusion of autologous PRP to improve outcomes for women with RIF remains an important area of research in ART. However, the current evidence is insufficient to inform clinical practice, highlighting the need for well-designed studies to provide clearer guidance.

Unraveling shared diagnostic genes and cellular microenvironmental changes in endometriosis and recurrent implantation failure through multi-omics analysis

Endometriosis and Recurrent Implantation Failure (RIF) are both pivotal clinical issues within the realm of reproductive medicine, sharing significant overlap in their pathophysiological mechanisms. However, research exploring the commonalities between these two conditions remains relatively scarce, and reliable shared diagnostic biomarkers have yet to be identified. In this study, we integrated transcriptomic and single-cell sequencing data from the Gene Expression Omnibus (GEO) database to identify shared diagnostic genes and alterations in the cellular microenvironment between EMs and RIF. Differential expression analysis and weighted gene co-expression network analysis (WGCNA) were employed to identify key genes. Machine learning algorithms, including Random Forest (RF) and XGBoost, were utilized to screen for shared diagnostic genes, which were subsequently validated through receiver operating characteristic (ROC) analysis and clinical prediction models. Single-cell analysis was conducted to investigate the expression patterns of these diagnostic genes across various cellular subpopulations. Additionally, gene set enrichment analysis (GSEA) and competing endogenous RNA (ceRNA) network analysis were employed to further elucidate the biological functions and regulatory mechanisms of these genes. A total of 16 key genes were identified, which were predominantly expressed in fibroblasts. Through machine learning, the optimal model combining RF and XGBoost was selected to identify the shared diagnostic genes PDIA4 and PGBD5. Single-cell analysis revealed significant differences in the expression of these diagnostic genes in fibroblasts between normal and disease states. ROC analysis showed that the Area Under the Curve (AUC) values for individual genes in disease diagnosis were all above 0.7. The constructed clinical prediction model demonstrated robust predictive capacity for the disease. Immune infiltration analysis indicated that M2 macrophages and γδ T cells play important roles in the pathogenesis of EMs and RIF. GSEA revealed that these genes are involved in immune responses, vascular function, and hormone regulation, and are regulated by miR-3121-3p. This study provides comprehensive insights into the shared cellular microenvironmental alterations and molecular mechanisms underlying EMs and RIF. The identification of PDIA4 and PGBD5 as shared diagnostic biomarkers offers new avenues for early diagnosis and targeted treatment of EMs-related RIF. Future work will focus on validating these findings in larger cohorts and exploring their therapeutic potential.

Comparison of diagnostic tests for chronic endometritis and endometrial dysbiosis in recurrent implantation failure: Impact on pregnancy outcomes

Chronic endometritis (CE) and endometrial dysbiosis (ED) are major causes of recurrent implantation failure (RIF). CE is diagnosed via hysteroscopy or the endometrial CD138 test; ED is examined using endometrial microbiome testing with next-generation sequencing. ED is characterized by a reduction in Lactobacillus species. However, correlations between the results of the three tests and the efficacy of treatment against CE and ED in pregnancy outcomes remain unclear. We analyzed 73 patients with RIF who underwent all three tests (hysteroscopy, endometrial CD138 test, and endometrial microbiome test). Patients with CE received antibiotics, whereas those with ED received antibiotics and vaginal Lactobacillus probiotics. The incidences of CE diagnosed using hysteroscopy and the CD138 test were 56.2 and 49.3%, respectively, and the prevalence of ED was 53.4%. No correlations were observed among the test-positive individuals in these three tests. Among patients with ED, 88.9% had a post-treatment clinical pregnancy, a significantly higher rate than that in patients without ED (p = 0.021). Multivariate analysis demonstrated that ED was associated with clinical pregnancy (odds ratio (OR): 6.29, p = 0.031). In conclusion, the three tests detected different populations of patients with RIF. ED diagnosed using the endometrial microbiome test was associated with favorable pregnancy outcomes after testing.

Comparative efficacy of intrauterine infusion treatments for recurrent implantation failure: a network meta-analysis of randomized controlled trials

OBJECTIVE

Recurrent implantation failure (RIF) is a significant challenge in assisted reproductive technology (ART), affecting many women undergoing in vitro fertilization (IVF). This study aims to compare the efficacy of various intrauterine infusion treatments, including granulocyte colony-stimulating factor (G-CSF), platelet-rich plasma (PRP), human chorionic gonadotropin (HCG), and peripheral blood mononuclear cells (PBMCs), in improving clinical pregnancy rate (CPR), live birth rate (LBR), and miscarriage rate (MR) in women with RIF.

METHODS

A comprehensive search was conducted in multiple databases, including Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Embase, Web of Science, and China National Knowledge Internet (CNKI), to identify randomized controlled trials (RCTs) evaluating the efficacy of intrauterine infusion treatments for RIF. Data extraction and quality assessment were performed independently by two reviewers. Network meta-analysis was conducted using a random-effects model to compare the outcomes of different treatments.

RESULTS

A total of 25 RCTs involving 3035 patients were included in the network meta-analysis. The treatments involved G-CSF, PRP, HCG, PBMCs, placebo, and blank control. The results of the network meta-analysis for CPR and LBR were statistically significant among treatments, but there was no statistical significance in MR. The surface under cumulative ranking curve (SUCRA) ranking of CPR and LBR showed that intrauterine infusion treatments of G-CSF, PRP, HCG, and PBMCs were much better than placebo and blank. The SUCRA values of CPR were ranked probabilistically from high to low as follows: PRP (84.5%) > PBMCs (76.5%) > G-CSF (65.7%) > HCG (52.5%) > placebo (20.8%) > blank (0.1%). The SUCRA values of LBR were ranked probabilistically from high to low as follows: PRP (81.4%) > PBMCs (64.6%) > G-CSF (58.0%) > HCG (48.7%) > placebo (42.4%) > blank (4.9%).

CONCLUSION

All these findings confirmed that intrauterine infusions of PRP and PBMCs significantly improve pregnancy outcomes in women with RIF. PRP emerged as the most effective treatment. However, to establish the most effective approach for managing patients with RIF, future research should prioritize direct and robust comparisons between PRP and other therapeutic strategies, ensuring a comprehensive evaluation of their relative efficacy.

Exploration of ferroptosis-related biomarkers with prognostic capability in RIF based on WGCNA

PURPOSE

To explore the association of ferroptosis with repeated implantation failure (RIF) and prognostic capability of ferroptosis-related genes.

METHODS

Data in GSE106602 from the GEO database were used for gene co-expression network construction to confirm ferroptosis-related genes compared to gene sets that were downloaded from FerrDB. Then these genes were analyzed for functional enrichment and validated using endometrium samples from our center. ImplantScore and ROC curve were constructed for prognostic correlation analysis.

RESULTS

We observed that ferroptosis probably participated in RIF according to bioinformatics analysis on a gene set which exhibited a strong association with RIF from WGCNA. Fifty-four ferroptosis-related genes in the gene set were subsequently verified, and the PPI network was established for underlying interactions among them. There were 23 hub genes with differential expression in RIF and six of them (PML, LCN2, PRKAA1, BACH1, SLC7A11, and CAMKK2) showed significant correlation with implantation outcomes using samples collected from our center. Therefore, we combined the six genes and constructed an ImplantScore whose AUC reached 0.891, higher than the AUC of each single gene, respectively. ImplantScore of six genes with down-regulated expression in the group with failed implantation were much lower than that with successful outcome.

CONCLUSION

Our results demonstrated the potential prognostic functions of ferroptosis-related biomarkers in RIF, which will provide novel perspectives for further research and clinical applications.

Shared diagnostic biomarkers and underlying mechanisms between endometriosis and recurrent implantation failure

BACKGROUND

Endometriosis (EMs) is a common condition that causes dysmenorrhea, chronic pelvic pain, and infertility, affecting millions of women worldwide. Despite the use of assisted reproductive technology, EMs patients often experience lower embryo implantation rates and recurrent implantation failure (RIF) due to impaired uterine endometrial receptivity. This study aims to identify shared diagnostic genes and underlying mechanisms between EMs and RIF using integrated transcriptomic analysis and machine learning with Gene Expression Omnibus (GEO) datasets.

METHODS

We analyzed GSE11691, GSE7305, GSE111974, and GSE103465 as training datasets for EMs and RIF, and GSE25628 and GSE92324 as validation datasets. Differentially expressed genes (DEGs) and Weighted Gene Co-Expression Network Analysis (WGCNA) identified key genes specific to and shared by EMs and RIF. Machine learning algorithms were used to determine the shared diagnostic gene, whose performance was validated in both training and validation datasets. Single-gene Gene Set Enrichment Analysis (GSEA) revealed shared biological processes in EMs and RIF, while CIBERSORT analysis highlighted similarities and differences in immune infiltration between the two conditions. Finally, endometrial samples from healthy controls, EMs, and RIF patients were collected, and qRT-PCR was performed to validate the diagnostic gene.

RESULTS

We identified 48 shared key genes between EMs and RIF. The diagnostic gene EHF was selected through machine learning algorithms, and its diagnostic performance was validated in both training and validation datasets. ROC curve analysis demonstrated excellent diagnostic accuracy of EHF for both diseases. Gene Set Enrichment Analysis (GSEA) revealed that both conditions shared biological processes, including dysregulated extracellular matrix remodeling and abnormal immune infiltration. Furthermore, we validated the expression of EHF in endometrial samples from healthy controls, EMs, and RIF patients. Additionally, we characterized the immune microenvironment in EMs and RIF, highlighting changes in immune cell components associated with EHF.

DISCUSSION

The diagnostic gene EHF identified in this study may serve as a key link between EMs and RIF. The shared pathological processes in both conditions involve alterations in the extracellular matrix and subsequent changes in the immune microenvironment. These findings provide novel insights into potential therapeutic strategies for improving infertility treatment in patients with EMs.

The effect of vitamin D supplementation and vaginal probiotics on fertility in women with recurrent implantation failure: A randomized clinical trial

Recurrent implantation failure (RIF) is a significant obstacle in assisted reproductive technology, affecting approximately 10 % of couples undergoing in vitro fertilization (IVF). Emerging evidence suggests that vaginal probiotics and vitamin D supplementation may improve reproductive outcomes. This randomized clinical trial evaluated the effects of these interventions on fertility in women with RIF and thin endometrium (<6 mm). A total of 112 women with a history of RIF were randomized into four groups: vaginal probiotics, vitamin D supplementation, a combination of both, or standard IVF treatment (control). The primary outcome was the pregnancy rate, confirmed by β-hCG testing and ultrasound. Secondary outcomes included changes in Th1/Th2 ratio, natural killer (NK) cell activity, and cytokine profiles. The combination group demonstrated the highest pregnancy rate (46.4 %), which was significantly higher compared with the probiotics ((14.2 %), p = 0.008), vitamin D ((17.8 %), p = 0.002), and control groups ((10.7 %), p = 0.003). Only the combination therapy significantly reduced the Th1/Th2 ratio (p < 0.001) and NK cell activity (p < 0.001), while significantly increasing IL-4 and TGF-β and decreasing IFN-γ levels (all p < 0.001). These findings suggest that combined vaginal probiotics and vitamin D supplementation may improve pregnancy outcomes by modulating the immune responses in women with RIF. This dual intervention may represent a promising strategy for enhancing fertility in this population of RIF patients.

The impact of long-acting Gonadotropin-releasing hormone agonist pretreatment on the clinical pregnancy outcomes of hormone replacement therapy-frozen embryo transfer in recurrent implantation failure patients with and without polycystic ovary syndrome: a retrospective clinical study

BACKGROUND

Several studies have demonstrated that pre-treatment with long-acting Gonadotropin-Releasing Hormone agonists (GnRHa) can significantly enhance the clinical pregnancy rate among recurrent implantation failure (RIF) patients. Investigations have also suggested that GnRHa pre-treatment could ameliorate the clinical pregnancy and live birth rates in polycystic ovary syndrome (PCOS) patients. But there is a dearth of research on whether long-acting GnRHa pre-treatment yields superior clinical outcomes for RIF patients with PCOS.

METHODS

The retrospective study enrolled 1602 patients under the age of 40 meeting the criteria for RIF at the Reproductive Medicine Center of Nanjing Drum Tower Hospital, who underwent frozen-thawed embryo transfer (FET) between January 2017 and December 2021. All cycles were categorized into hormone replacement therapy (HRT) Group (n = 1283) and GnRHa-HRT Group (n = 319), contingent on the usage of long-acting GnRHa pretreatment. Primary outcomes investigated in this study was clinical pregnancy rate, while live birth rate and early miscarriage rate were deemed as secondary outcomes. Univariate analysis and a multivariate logistic regression model were employed to assess the impact of GnRHa pretreatment on the clinical pregnancy rate in RIF patients. The influence of long-acting GnRHa pretreatment on clinical pregnancy outcomes was re-examined in PCOS and non-PCOS subgroups. Additionally, an interaction analysis was performed to evaluate the effect of PCOS on the relationship between long-acting GnRHa pretreatment and the clinical pregnancy rate.

RESULTS

Multiple regression analysis showed that long-acting GnRHa pretreatment had a positive impact on the clinical pregnancy rate (aOR = 1.51, 95%CI: 1.15-1.99, P = 0.003). We divided the RIF population into two subgroups, for PCOS patients, although the clinical pregnancy rate was higher in women who received GnRHa pretreatment compared to those who did not, it was not statistically significant (aOR = 1.51, 95%CI: 0.81-2.82, P = 0.195). Interaction analysis suggested that for PCOS patients, there was no significant difference in the clinical pregnancy rate between women who received GnRHa pretreatment and those who did not (P interaction = 0.818), indicating that the effect of GnRHa pretreatment on the clinical pregnancy rate was not influenced by PCOS.

CONCLUSIONS

Our study demonstrates that long-acting GnRHa pretreatment can enhance clinical pregnancy outcomes in patients with RIF. Among RIF patients without PCOS, the clinical pregnancy rate exhibited a significant increase following GnRHa pretreatment compared to the control group. However, in RIF patients with concurrent PCOS, there was no significant elevation in the clinical pregnancy rate post-GnRHa pretreatment. Therefore, GnRHa pretreatment is effective in improving pregnancy outcomes for RIF patients. However, whether GnRHa pretreatment is suitable for RIF patients with PCOS requires more cautious clinical discussion.

Development of a novel chimeric lysin to combine parental phage lysin and cefquinome for preventing sow endometritis after artificial insemination

Sow endometritis is usually caused by multiple species of pathogenic bacteria. Numerous isolates from endometritis patients have developed antimicrobial resistance. Thus, novel antibacterial agents and strategies to combat endometritis are needed. A total of 526 bacteria, including Staphylococcus spp. (26.3%), Streptococcus spp. (12.3%), E. coli (28.9%), Enterococcus spp. (20.1%), Proteus spp. (9.5%), and Corynebacterium spp. (2.8%), were isolated from sows with endometritis. We constructed a novel chimeric lysin, ClyL, which is composed of a cysteine- and histidine-dependent amidohydrolase/peptidase (CHAP) catalytic domain from the phage lysin LysGH15 and a cell wall-binding domain (CBD) from the prophage lysin Lys0859. The activities of ClyL and Lys0859 were most pronounced for the Staphylococcus and Streptococcus strains isolated from sow endometritis and bovine mastitis, respectively. ClyL and Lys0859 were combined to create a phage lysin cocktail, which demonstrated a synergistic effect against the coinfection of Staphylococcus and Streptococcus in vitro and in vivo. Furthermore, the combination of phage lysin cocktail and cefquinome had a synergistic bactericidal effect on boar semen that did not influence the activity of sperm. Remarkably, the incidence rate of sow endometritis was 0% (0/7) when the combination of phage lysin cocktail and cefquinome was used in semen via artificial insemination compared with 50% (3/6) when PBS was administered. Overall, the administration of a phage lysin cocktail and cefquinome in semen via artificial insemination is a promising novel strategy to prevent sow endometritis after artificial insemination.

Granulocyte Colony Stimulating Factor Enhances Decidualization Process of Endometrial Stromal Cells Through STAT3/HOXA10 Axis

BACKGROUND

Recurrent implantation failure (RIF) is characterized by the repeated failure of implantation, often linked to impaired endometrial receptivity. This study investigates how granulocyte colony-stimulating factor (G-CSF) promotes endometrial stromal cell decidualization.

METHODS

THESCs (human telomerase reverse transcriptase-immortalized endometrial stromal cells) were used as an in vitro cell model to induce decidualization. The effects of G-CSF on the expression of decidualization genes and apoptosis during decidualization were examined. Additionally, a chemical inhibitor of signal transducer and activator of transcription 3 (STAT3) and the small interfering RNA (siRNA) targeting Homeobox A10 (Hoxa10) were employed to explore the involvement of the STAT3/HOXA10 axis in the action of G-CSF.

RESULTS

G-CSF promoted decidualization markers expression and suppressed apoptosis in THESCs Treatment with G-CSF enhanced STAT3 activation during decidualization induction. STAT3 inhibition diminished the effects of G-CSF on decidualization marker expression and apoptosis suppression. Furthermore, it was demonstrated that G-CSF increased Hoxa10 expression in a STAT3-dependent manner. Silencing Hoxa10 abrogated the effects of G-CSF on promoting decidualization.

CONCLUSION

G-CSF enhances decidualization of endometrial stromal cells via STAT3/HOXA10 axis activation. These findings suggest that optimal G-CSF delivery strategies could improve endometrial receptivity in RIF patients.

The use of propensity score matching to assess the effectiveness of the endometrial receptivity analysis in patients with recurrent implantation failure

Background

One potential cause of implantation failure is abnormal endometrial receptivity, and how to objectively evaluate endometrial receptivity has been a matter of great concern. Endometrial receptivity analysis (ERA), a next-generation sequencing-based test that assesses endometrial gene expression, may be valuable in predicting endometrial receptivity, but whether ERA improves pregnancy outcomes in patients with recurrent implantation failure (RIF) is currently controversial. The purpose of this study was to investigate the effect of ERA on pregnancy outcomes in patients with RIF.

Methods

We performed a retrospective cohort study analysis for a population of patients with RIF undergoing frozen embryo transfer (FET) cycles in the reproductive center of the Third Affiliated Hospital of Zhengzhou University from January 2019 to December 2022(n=1598). FET cycles with personalized embryo transfer (PET) under ERA guidance were included in the ERA group (n=43); after using propensity score matching (PSM), a total of 120 FET cycles were included as a control group. Pregnancy outcomes were compared between the two groups. Further, the relationship between the number of previous implant failures and the rate of implant window displacement was discussed. The factors affecting the window of implantation (WOI) displacement were also assessed.

Results

There was no statistically significant difference in embryo implantation rate, clinical pregnancy rate, spontaneous abortion rate, and live birth rate between the ERA group and the matched control patients (P > 0.05). There was no significant difference in the rate of WOI displacement between patients in the moderate or severe groups (P > 0.05) and no significant difference in pregnancy outcome ( P>0.05). Finally, analysis of the clinical data of patients in the receptive and non-receptive groups did not uncover any factors influencing WOI displacement.

Conclusion

The results of the study showed no significant difference in pregnancy outcomes in patients who received ERA compared to those who did not.

Anti-Adhesive Podocalyxin Expression Is Disrupted in Recurrent Implantation Failure

Objectives: The downregulation of anti-adhesive regulatory proteins and upregulation of adhesive genes are critical for the receptive endometrium. This study was designed to determine whether switching between the anti-adhesive podocalyxin (PDX) and adhesive HOXA10 receptivity modulator occurs in the endometrium of women with recurrent implantation failure (RIF). Methods: Twenty-four patients with RIF who could not conceive for three or more cycles despite good-quality embryo transfer constituted the study group. Twenty-four patients with unexplained infertility (UEI) matched for age, BMI, and infertility duration were included in the control group. Twenty women scheduled to undergo intrauterine device (IUD) placement for birth control were included in the comparative group. Endometrial tissue was collected from patients with RIF and UEI during egg retrieval after ovarian stimulation using the GnRH antagonist protocol. In the fertile group, endometrial tissues were collected during IUD insertion. HOXA10 mRNA expression was analyzed by qRT-PCR and PDX protein expression was analyzed by ELISA. The relative expression of endometrial HOXA10 mRNA was calculated using the 2-ΔΔCt equation. Results: The relative expression of HOXA10 mRNA in the RIF group was significantly lower than that in the UEI group (p < 0.001). HOXA10 mRNA expression in the fertile group was significantly higher than that in the RIF group and was similar to that in the UEI group. PDX expression in the RIF group was significantly higher than that in the UEI group (p < 0.001). PDX expression in the fertile group was significantly lower than in the RIF and UEI groups. A negative correlation was detected between the anti-adhesive PDX protein and adhesive HOXA10 (r = -0.797, p < 0.001). Although there was a positive correlation between endometrial thickness recorded on the day of hCG administration and HOXA10 (r = 0.590, p < 0.01), endometrial thickness was negatively correlated with PDX (r = -0.529, p < 0.01). Conclusions: The failed physiological downregulation of the anti-adhesive PDX protein in patients with RIF prevented the upregulation of adhesive HOXA10 mRNA.

Time-series single-cell transcriptomic profiling of luteal-phase endometrium uncovers dynamic characteristics and its dysregulation in recurrent implantation failures

Understanding human endometrial dynamics in the establishment of endometrial receptivity remains a challenge, which limits early diagnosis and treatment of endometrial-factor infertility. Here, we decode the endometrial dynamics of fertile women across the window of implantation and characterize the endometrial deficiency in women with recurrent implantation failure. A computational model capable of both temporal prediction and pattern discovery is used to analyze single-cell transcriptomic data from over 220,000 endometrial cells. The time-series atlas highlights a two-stage stromal decidualization process and a gradual transitional process of the luminal epithelial cells across the window of implantation. In addition, a time-varying gene set regulating epithelium receptivity is identified, based on which the recurrent implantation failure endometria are stratified into two classes of deficiencies. Further investigation uncovers a hyper-inflammatory microenvironment for the dysfunctional endometrial epithelial cells of recurrent implantation failure. The holistic characterization of the physiological and pathophysiological window of implantation and a computational tool trained on this temporal atlas provide a platform for future therapeutic developments.

From live birth to live birth: a strong correlation between the outcomes of first and second frozen-thawed euploid blastocyst transfers from sibling oocytes

PURPOSE

To investigate any correlation between the outcomes of the first euploid frozen-thawed blastocyst embryo transfer (FBT) and the subsequent euploid FBT derived from sibling oocytes.

METHODS

This retrospective study analyzed data from 1051 women who underwent preimplantation genetic testing for aneuploidy and had a euploid FBT. Of these patients, 159 underwent a second transfer. The primary outcome was the live birth rate.

RESULTS

Overall, 159 women who underwent a second euploid FBT were categorized into two subgroups depending on the implantation success of the first FBT. Of these patients, 94 (59.1%) belonged to the nonclinical group, signifying a negative result or a biochemical pregnancy. The remaining 65 (40.9%) patients belonged to the clinical group, indicating either a miscarriage or a live birth. In the binary logistic regression analysis, the live birth outcome during the first euploid FBT was a statistically significant and independent predictor of live birth in the subsequent FBT [odds ratio 4.14, 95% confidence interval (1.184-14.531), p < 0.026). Miscarriages, including those that occurred before intracytoplasmic sperm injection and in the first euploid FBT, reduced the live birth rate by approximately 34% (p < 0.027). No significant difference in the miscarriage rate was found between the two subgroups (19.2% (10/52) vs. 25.4% (14/55), p = 0.38).

CONCLUSION

The live birth outcome of the second euploid FBT is mainly determined by the live birth outcome of the first. Miscarriages that occurred before in vitro fertilization negatively affect the live birth outcome.

Shoutai Pill Enhances Endometrial Receptivity in Controlled Ovarian Hyperstimulation Mice by Improving the In-Vivo Immune Environment

BACKGROUND

The Shoutai pill (STP) is a classic formulation in traditional Chinese medicine. Preliminary experimental observations from our study suggest that it is effective in enhancing endometrial receptivity. However, the underlying mechanisms by which STP influences endometrial receptivity remain to be elucidated.

OBJECTIVE

The objective of this study is to investigate the effects and mechanisms of the STP formulation in enhancing endometrial receptivity in controlled ovarian hyperstimulation (COH) model mice.

METHODS

The network pharmacology analysis identified target proteins associated with the reduction of endometrial receptivity by STP. The COH mouse model was established using the GnRHa+PMSG+HCG protocol. The levels of MHC-1 and MHC-2 in mouse serum were measured using the ELISA method, while the levels of IL-1β, IL-4, IL-10, IP-10, IL-1a, IL-2, IL-17, TNF-a, and IFN-y were measured using liquid chip technology.

RESULTS

STP exhibited a significant improvement in the immune environment of COH model mice. The major active components of STP were identified as beta-sitosterol and quercetin, among others. Furthermore, AKT1, VEGFA, and several immune factors, such as TNF, IFN, IL- 1β, and IL-10, were identified as key targets for regulating endometrial receptivity. STP enhanced the expression of IL-10, IL-4, and IP-10 in the mice while reducing the expression levels of IL-2, IL-17, TNF-α, and IFN-γ in COH mice. These effects led to the modulation of early high expression of IL-1β and an improvement in endometrial receptivity.

CONCLUSION

This study demonstrates that STP can modulate in-vivo immune factors throughout the COH process, subsequently restoring the immune equilibrium within the endometrium, thereby enhancing the endometrial receptivity in the COH model mice.

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.

The role of probiotics in restoring the Th1 to Th2 ratio in women experiencing recurrent implantation failure; a double-blind randomized clinical trial

BACKGROUND

Among the complex causes of infertility, Recurrent Implantation Failure (RIF) stands out as a challenging condition. Immunological aberrations are closely implicated in RIF, particularly the imbalance between T helper 1 (Th1) and T helper 2 (Th2) cytokines. Interest in harnessing probiotics to enhance fertility outcomes in RIF-affected women is growing. This study aimed to investigate the potential of probiotics in restoring the Th1 to Th2 ratio and enhancing implantation outcomes in women experiencing RIF.

METHODS

A double-blinded randomized controlled trial enrolled 50 women with a record of at least three RIFs and 50 women with successful pregnancies as a control group in our study. RIF patients were randomly assigned to either the probiotic intervention group (n = 25) or the placebo group (n = 25). The probiotic group administered two tablets per day for 6 months the probiotic tablets that contained prebiotic. At the same time, the placebo group received an identical-looking placebo. Flow cytometry technique was used to evaluate Th1 and Th2 cell frequencies. Gene expression of IL-4, IL-10, TNF-α and IFN-ɣ was analyzed using QRT-PCR. Serum concentrations of IL-4, IL-10, TNF-α and IFN-ɣ cytokines were evaluated using the ELISA technique.

RESULTS

Flow cytometry analysis revealed significantly higher Th1 cell percentages in RIF patients compared to healthy controls, while healthy controls exhibited more significant Th2 cell proportions. Probiotic intervention led to a reduction in Th1 cells and an increase in Th2 cells in RIF patients. ELISA analysis indicated higher proinflammatory and lower anti-inflammatory cytokines compared to controls. After probiotic treatment, TNF-α and IFN-ɣ levels decreased, while IL-10 and IL-4 levels increased in RIF patients. QRT-PCR analysis showed no significant differences in cytokine gene expression between RIF patients before intervention. After probiotic therapy, pro-inflammatory cytokine expression decreased, and anti-inflammatory cytokine expression increased. Placebo treatment resulted in limited changes. Probiotic intervention effectively modulated the Th1 to Th2 ratio in RIF patients, evidenced by reduced Th1 cell percentages, enhanced Th2 cell populations, and cytokine level adjustments. The probiotic intervention improved implantation outcomes in women with RIF, as evidenced by a higher clinical pregnancy rate in the treatment group compared to the placebo group (p = 0.037).

CONCLUSION

These findings highlight the potential of probiotics in restoring immune balance and improving implantation outcomes in women with RIF.

Engineered exosome as a biological nanoplatform for drug delivery of Rosmarinic acid to improve implantation in mice with induced endometritis

Endometritis is an inflammatory and histopathologic disease in uterine tissues that interferes with the proper decidualization and implantation of the embryo. In this study, rosmarinic acid (RA) is used as an anti-inflammatory agent that encapsulates in exosomes and is used to attenuate lipopolysaccharide (LPS)-induced endometritis and improve implantation. For this purpose, exosomes were loaded with RA and then administrated into the animal groups, including RA, exosome, RA plus exosome (RA + Exo), and RA-loaded exosomes (RALExo) groups. The concentrations of RA or exosomes used in this study were 10 mg/kg, and the compounds were injected into the uterine horn 24 h following the induction of endometritis. Upon the presence of inflammation detected by the histopathological method, the most proper groups were mated with male mice. The effect of the treatment group on the implantation rate, progesterone levels, and gene expressions were assessed by Chicago Blue staining, enzyme-linked immunosorbent assay (ELISA), and Quantitative PCR (qPCR), respectively. Results showed RALExo10 and RA10 + Exo10 groups improved pathological alterations, enhanced progesterone levels, increased implantation rate, as well as heightened expression levels of Leukemia inhibitory factor (LIF) and Mucin-16 (MUC-16) genes. Besides, the expression levels of inflammatory cytokines, including Transforming growth factor-β (TGF-β), Interlukine-10 (IL-10), Interlukine-15 (IL-15), and Interlukine-18 (IL-18), were regulated. Our findings indicated that the expression of LIF, Muc-16 genes as well as IL-18, were significantly correlated with serum progesterone concentrations and the implantation rate in the treatment groups. The RALExo10 and RA10 + Exo10 groups showed ameliorated implantation rates in experimental groups.

Effect of intravenous immunoglobulin therapy in recurrent implantation failure: A Systematic review and meta-analysis

BACKGROUND

IVIg is a pooled donor immunoglobulin preparation, used for auto-immune and inflammatory diseases. In assisted reproduction it receives considerable scepticism. Clinical data is expanding, but individual studies may be perceived as weak, meaning an updated appraisal of evidence in implantation failure is needed.

OBJECTIVE

To assess the efficacy of IVIg in Recurrent Implantation Failure (RIF) following assisted reproductive technology.

DESIGN

Systematic review and meta-analysis of randomized controlled trials and observational studies comparing IVIg therapy against placebo in a defined RIF population.

MATERIALS AND METHODS

A comprehensive literature search, identifying studies involving RIF following ART, using pre-conception IVIg. Primary outcomes were clinical pregnancy (CPR), live birth (LBR), implantation (IR), and miscarriage rates (MR). The selection process yielded twelve studies, including 1023 cases and 2276 controls.

RESULTS

A significant increase in CPR (OR=5.14, 95 % CI: 2.33-11.30, p<0.001) and LBR (OR=4.60, 95 % CI:2.44-8.68, p<0.001) is demonstrated in IVIG-treated patients, with an improvement in IR (OR=2.35, 95 % CI: 1.04-5.29, p=0.039) and reduction in MR (OR=0.60, 95 % CI: 0.37-0.97, p=0.036). Substantial heterogeneity was identified across studies, which was addressed through subgroup analyses, assessing if the variability in may be attributed to study-specific factors.

CONCLUSIONS

IVIg may enhance implantation, clinical pregnancy, and live birth rates in RIF patients, underscoring benefit for specific populations. Positive immunological risk factors may predict potential candidates, but it could also be of use in unexplained RIF with high-grade embryos. These findings highlight the importance of personalized therapeutic strategies to improve ART outcomes for complex cases.

CDC42 deficiency leads to endometrial stromal cell senescence in recurrent implantation failure

STUDY QUESTION

Does the downregulation of cell division cycle 42 (CDC42) protein in endometrial stroma lead to endometrial senescence in patients with recurrent implantation failure (RIF), and what is the potential mechanism?

SUMMARY ANSWER

CDC42 deficiency causes endometrial stromal senescence and decidualization defects, impairing uterine receptivity of RIF patients, via activation of Wnt signaling pathway.

WHAT IS KNOWN ALREADY

Uterine aging is unique due to the cyclic remodeling and decidualization of endometrial tissue. Several transcriptomic studies have reported increased senescence in the endometrium in young patients with RIF. Our previous transcriptomic sequencing study discovered that endometrium from women with RIF showed downregulation of CDC42, which is an essential molecule affected by various senescence-related diseases.

STUDY DESIGN, SIZE, DURATION

The endometrial samples of a total of 71 fertile control patients and 37 RIF patients were collected to verify the association between CDC42 expression and endometrial senescence of RIF patients. Primary endometrial stromal cells (EnSCs) were isolated from endometrial biopsies taken from patients without any endometrial complications and planning to undergo IVF, then subjected to adenovirus-mediated CDC42 knockdown and decidualization induction to explore the detailed mechanism by which CDC42 governs stromal senescence and decidualization. Wnt inhibitor XAV-939 was used to correct the endometrial senescence and decidualization defect.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Senescence was determined by cell cycle arrest markers (e.g. P16, P21, and P53), SASP molecules (e.g. IL6 and CXCL8), and SA-β-gal staining. Masson's staining and Sirius Red staining were used to detect the endometrial fibrosis. Decidualization was evaluated by the mRNA expression and protein secretion of PRL and IGFBP1, F-actin immunostaining, and the BeWo spheroids 'in vitro implantation' model. Methods used to assess cell function included adenovirus transduction, RNA-sequencing, bioinformatic analysis, western blotting, RT-qPCR, ELISA, and immunofluorescence.

MAIN RESULTS AND THE ROLE OF CHANCE

Here, we observed remarkably increased levels of stromal senescence and fibrosis, along with stromal CDC42 deficiency, in the endometrium of patients with RIF (P < 0.001). Knockdown of CDC42 effectively induced premature senescence in EnSCs, leading to aberrant accumulation of senescent EnSCs and collagen deposition during decidualization. CDC42 deficiency in EnSCs restrained the decidualization differentiation and receptivity to trophoblast cells. Transcriptomic analysis revealed Wnt signaling activation as a critical downstream alteration in CDC42-deficient EnSCs. Mechanistically, CDC42 interacted with AKT competitively to impede the binding of GSK3β to AKT. Knockdown of CDC42 increased AKT-mediated phosphorylation of GSK3β to inactivate the Axin-GSK3β destruction complex, leading to accumulation and nuclear translocation of β-catenin. Importantly, Wnt signaling inhibitors partially corrected the endometrial senescence caused by CDC42 deficiency, and improved both decidualization and trophoblast invasion.

LARGE SCALE DATA

RNA-seq data sets generated in this study have been deposited at the NCBI database with BioProject accession number PRJNA1102745.

LIMITATIONS, REASONS FOR CAUTION

The present study was based on in vitro cell cultures. Further studies involving CDC42-regulated endometrial senescence are needed in knockout mice model and human endometrial assembloids.

WIDER IMPLICATIONS OF THE FINDINGS

In addition to uncovering endometrial senescence in RIF, our findings underscore the significance of CDC42 in modulating EnSC senescence to maintain the decidualization function, and suggest Wnt signaling inhibitors as potential therapeutic agents for alleviating endometrial senescence.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Natural Science Foundation of China [82271698 (R.J.), 82030040 (H.S.), 82288102 (H.W.), and 82371680 (G.Y.)]; the Natural Science Foundation of Jiangsu Province [BK20231117 (R.J.)]; and the Medical Science and Technology Development Foundation of Nanjing Department of Health [YKK23097 (Y.Z.)]. The authors declare no potential conflicts of interest.

The effect of sequential embryo transfer on pregnancy outcomes in patients with recurrent implantation failure: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

The aim of our study was to assess the impact of sequential embryo transfer on pregnancy outcomes among patients with recurrent implantation failure (RIF).

METHODS

We conducted a comprehensive search across various databases for eligible clinical trials from inception to January 2024. Randomized controlled trials (RCTs) were included if they compared sequential embryo transfer, comprising both cleavage-stage and blastocyst-stage embryos, with other transfer protocols in infertile women with repeated implantation failure. Meta-analysis was performed using Revman software. Our primary focus was on the ongoing pregnancy rate. Our secondary measures included rates of chemical pregnancies, clinical pregnancies, miscarriages, and multiple pregnancies.

RESULTS

Seven RCTs, encompassing 909 patients, met the inclusion criteria. Sequential embryo transfer demonstrated a significant increase in the ongoing pregnancy rate compared to the control group (OR = 2.28, 95% CI [1.46, 3.56], p = 0.003). Moreover, the sequential embryo transfer group exhibited notable improvements in chemical and clinical pregnancy rates. There were no statistically significant differences between the groups regarding multiple pregnancy and miscarriage rates (p > 0.05).

CONCLUSIONS

Sequential embryo transfer shows promise in enhancing pregnancy outcomes among RIF patients. However, additional trials are warranted to validate our findings.

Endometrial scratching and intralipid treatment-no general recommendations

Objectives

Endometrial scratching (ES) and/or intravenous intralipid therapy (in cases of increased uterine natural killer cells, uNKs) are still conducted in several fertility centers as "add-on" treatments in patients undergoing ART, although convincing evidence for beneficial effects is lacking.

Study design

In this retrospective study, associations between ES treatment or additional intralipid therapy and pregnancy and live birth rates of 1,546 patients undergoing 2,821 IVF-/ICSI-treatment cycles with fresh or frozen embryo transfers in a German fertility-center between 1st January 2014 and 31th May 2017 were analyzed.

Results

Overall pregnancy and live birth rates for all 2,821 treatment cycles (468 cycles with ES) were 32.8% and 23.5%. There were no statistically significant differences in pregnancy or live birth rates between first treatment cycles with and without ES (p = 0.915 and p = 0.577) or between second cycles following an unsuccessful first cycle with and without ES (p = 0.752 and p = 0.623). These results were confirmed using multivariable generalized estimating equations (GEE) models accounting for non-independency of multiple treatment cycles per patients that included all cycles and showed no significant effect of ES on pregnancy (p = 0.449) or live birth rates (p = 0.976). Likewise, a GEE model revealed no significant effect of intralipid treatment on pregnancy (p = 0.926) and live birth rates (p = 0.727).

Conclusions

Our results reveal no evidence that ES increases the pregnancy or live birth rates in women undergoing their first or further IVF cycle with fresh or frozen embryo transfer. Intralipid treatment was also not beneficial. Even if patients explicitly ask for it, these procedures are not recommended outside of clinical studies.

WD-repeat containing protein-61 regulates endometrial epithelial cell adhesion indicating an important role in receptivity

Endometrial receptivity is crucial for successful embryo implantation during early pregnancy. The human endometrium undergoes remodeling within each menstrual cycle to prepare or become receptive to an implanting blastocyst in the mid-secretory phase. However, the mechanisms behind these changes are not fully understood. Recently, using hormone-treated endometrial organoids to model receptivity, we identified that the transcriptional regulator WD-repeat-containing protein-61 (WDR61) was reduced in organoids derived from infertile women. In this study, we aimed to determine the role of WDR61 in endometrial receptivity. Here, we demonstrated that WDR61 immunolocalizes in the nuclei and cytosol of endometrial glandular epithelium, luminal epithelium, and stroma. The staining intensity of WDR61 was significantly higher during the receptive mid-secretory phase compared to the non-receptive proliferative phase in fertile women. In a functional experiment to model blastocyst adhesion to the endometrial epithelium, we found that adhesion of cytotrophoblast progenitor spheroids was blocked when siRNA was used to knockdown WDR61 in primary endometrial epithelial cells. Similarly, in Ishikawa cells (a receptive human endometrial epithelial cell line), siRNA knockdown of WDR61 significantly reduced the cell adhesive and proliferative capacities. qPCR revealed that WDR61 knockdown reduced expression of key genes involved in receptivity including HOXD10, MMP2, and CD44. Chromatin immunoprecipitation sequencing demonstrated that WDR61 directly targeted 2022 genes in Ishikawa cells, with functions including focal adhesion, intracellular signaling and epithelial-mesenchymal transition. Overall, these findings suggest that WDR61 promotes endometrial receptivity by modulating epithelial cell focal adhesions, proliferation, and epithelial-mesenchymal transition.

Research Progress on the Impact of Human Chorionic Gonadotropin on Reproductive Performance in Sows

Human chorionic gonadotropin is a glycoprotein hormone produced by human or humanoid syncytiotrophoblasts that differentiate during pregnancy. Due to its superior stability and long-lasting effects compared to luteinizing hormone, it is often used to replace luteinizing hormone to regulate reproductive performance in sows. Human chorionic gonadotropin promotes oocyte maturation, follicle development, and luteinization, thereby increasing conception rates and supporting early embryonic development. In sow reproductive management, the application of human chorionic gonadotropin not only enhances ovulation synchrony but also improves the success rate of embryo implantation by regulating endometrial receptivity and immune mechanisms, significantly enhancing overall reproductive performance. This article primarily reviews the application of human chorionic gonadotropin in sow follicle development, luteal maintenance, and embryo implantation, providing theoretical support for its use in improving reproductive performance in sows.

MicroRNAs, endometrial receptivity and molecular pathways

MicroRNAs (miRNAs) are a type of specific molecules that control the activities of the uterus, such as the process of cellular maturing and evolution. A lot of substances like growth factors, cytokines, and transcription factors play a role in embryo-endometrial interaction. MiRNAs could regulate various these factors by attaching to the 3' UTR of their mRNAs. Moreover, current research show that miRNAs participate in formation of blood vessels in endometrium (miR-206, miR-17-5p, miR-16-5p…), decidualization (miR-154, miR-181, miR-9…), epithelial-mesenchymal transition (miR-30a-3p), immune response (miR-888, miR-376a, miR-300…) embryo attachment (miR-145, miR-27a,451…) and pinopod formation (mir-223-3p, mir-449a, mir-200c). In this study, the focus is on the role of miRNAs in managing the uterus' receptivity to an embryo and its ability to facilitate attachment. More specifically, we are exploring the mechanisms by which miRNAs regulate the presence of specific molecules involved in this crucial physiological process.

Effects of unequal-sized pronuclei and their origin on embryo development and obstetric outcomes: a time-lapse retrospective study

RESEARCH QUESTION

Do maternal and paternal pronuclear sizes and their relative differences affect embryonic development, morphokinetics and pregnancy outcomes in human embryos?

DESIGN

A total of 2516 fertilized oocytes with two pronuclei from 1207 patients were assessed using a time-lapse culture system. The associations between the pronuclear area immediately before pronuclear breakdown and its relative ratio (PNR), and embryonic, pregnancy and perinatal outcomes, were retrospectively evaluated. Perinatal outcomes were obtained from a self-reported questionnaire. Zygotes were stratified by PNR and origin of the pronuclei; embryo development, morphokinetics and morphological alterations were compared among the zygotes.

RESULTS

Areas of maternal and paternal pronuclei were not correlated with embryonic, pregnancy and perinatal outcomes. Zygotes with a PNR lower than the median (<0.88, unequal-sized pronuclei) had impaired embryo development (expanded blastocyst; P = 0.0100). Unequal-sized pronuclei resulted in a prolonged time interval between maternal and paternal pronuclear appearance, decreased nucleolus precursor body (NPB) alignment and increased incidence of asynchronous pronuclear breakdown, asymmetric division and multinucleation (P < 0.0001-0.0230). When the paternal pronucleus was smaller than the maternal pronucleus, the decreased NPB alignment, asynchronous pronuclear breakdown and abnormal cleavage were observed more frequently, resulting in significantly decreased blastocyst formation compared with the zygotes with equal-sized pronuclei (P < 0.0001-0.0030).

CONCLUSIONS

Zygotes with unequal-sized pronuclei had impairments in preimplantation development, particularly when the paternal pronucleus was smaller than the maternal pronucleus, without any adverse effects on maternal and obstetric outcomes. In addition to the number of pronuclei, evaluating PNR and pronuclear origin would be beneficial when fertilization is verified.

lncRNA-mediated immune system dysregulation in RIF; a comprehensive insight into immunological modifications and signaling pathways' dysregulation

The initial stage of biological pregnancy is referred to as implantation, during which the interaction between the endometrium and the fetus is crucial for successful implantation. Around 10% of couples undergoing in vitro fertilization and embryo transfer encounter recurrent implantation failure (RIF), a clinical condition characterized by the absence of implantation after multiple embryo transfers. It is believed that implantation failure may be caused by inadequate or excessive endometrial inflammatory responses during the implantation window, as the female immune system plays a complex role in regulating endometrial receptivity and embryo implantation. Recent approaches to enhance the likelihood of pregnancy in RIF patients have focused on modifying the mother's immune response during implantation by regulating inflammation. Long non-coding RNAs (lncRNAs) play a significant role in gene transcription during the inflammatory response. Current research suggests that dysfunctional lncRNAs are linked to various human disorders, such as cancer, diabetes, allergies, asthma, and inflammatory bowel disease. These non-coding RNAs are crucial for immune functions as they control protein interactions or the ability of RNA and DNA to form complexes, which are involved in differentiation, cell migration, and the production of inflammatory mediators. Given the apparent involvement of the immune system in RIF and the modulatory effect of lncRNAs on the immune system, this review aims to delve into the role of lncRNAs in immune system modulation and their potential contribution to RIF.

Pregnancy rate and time to pregnancy after recurrent implantation failure (RIF)-a prospective cohort follow-up study

PURPOSE

The goal of this study was to determine ongoing pregnancy rate, time to pregnancy and embryo transfers to pregnancy within a cohort of patients with recurrent implantation failure (RIF).

METHODS

IVF patients with RIF were included after referral to the RIF outpatient clinic. They received a questionnaire 1 year after inclusion. If data was missing, medical files were examined to determine pregnancy outcomes and conception methods. The ability of the RIF outpatient clinic to improve pregnancy chance or increase the number of patients who elected to continue treatment was beyond the scope of this study.

RESULTS

The cumulative incidence of ongoing pregnancy in IVF patients with RIF (n = 79) after 1 year of follow-up was 40.5% (95% confidence interval = 30.4-51.5%). Median time to pregnancy was 4 months. Pregnancy incidence increased gradually up to 5 embryo transfers (mostly single embryo transfers). The average embryo transfers to pregnancy were 7.3 transfers.

CONCLUSION

In IVF patients with RIF, up until the 5th embryo transfer, each transfer represents a good opportunity for ongoing pregnancy. This data can be used to counsel patients that regular treatment continuation seems to be well justified even when IVF patients fulfil the RIF criteria.

TRIAL REGISTRATION

CCMO: NL66835.068.18. METC 18-040. OMON: NL-OMON24778.

Global research trends in endometrial receptivity from 2000 to 2024: bibliometric analysis

Background

In recent years, extensive research has been conducted on endometrial receptivity (ER), with rapidly evolving research hotspots and trends. Our study aimed to explore the development of ER research from 2000 to the present and provide insights for future endeavors.

Materials and methods

Relevant research publications on ER from 2000 to 2024 were retrieved from the Web of Science Core Collection (WOSCC) database. CiteSpace, VOSviewer and Excel tools were employed to conduct the bibliometric analysis.

Results

A total of 3,354 articles were analyzed, revealing an overall upward trend in annual publication numbers, signifying the increasing attractiveness and research value of this field. Globally, China led with a notable advantage of 1,030 publications, followed by the United States (650) and Spain (251), constituting the first tier of international research. Valencia University topped the list of institutions with 108 publications, closely followed by Shanghai Jiao Tong University with 87. Fertility and Sterility (IF6.6, Q1) is the one with the largest number of publications, accounting for 7.96% of the total publications. The three most co-cited journals were Fertility and Sterility, Biology of Reproduction, and Human Reproduction. A co-citation reference analysis revealed that ER research can be categorized into ten major subfields, including embryo implantation, frozen embryo transfer, integrins, recurrent implantation failure, intrauterine adhesions, etc. Since 2020, the keywords with the strongest citation bursts include repeated implantation failure and frozen.

Conclusion

This study employs bibliometric analysis to offer researchers in the field of ER a comprehensive perspective. Since 2000, there has been a remarkable surge in the number of publications in the ER research field. These studies primarily concentrate on delving into the pathophysiological mechanisms of ER, with the primary objective of enhancing clinical pregnancy rates and live birth rates, benefiting more infertile patients. Currently, addressing the ER issues in patients with recurrent implantation failure represents the forefront of research. The primary treatment approaches currently in use involve optimizing embryo transfer timing and employing innovative strategies such as immunotherapy. These cutting-edge analyses not only provide new insights into the treatment of ER but also offer researchers fresh research directions, and staying abreast of the latest trends and advancements in the field.

Revolutionized attitude toward recurrent pregnancy loss and recurrent implantation failure based on precision regenerative medicine

Traditional treatment strategies for recurrent pregnancy loss (RPL) and recurrent implantation failure (RIF) often result in limited success, placing significant emotional and financial burdens on couples. However, novel approaches such as diagnostic gene profiling, cell therapy, stem cell-derived exosome therapy, and pharmacogenomics offer promising, personalized treatments. Combining traditional treatments with precision and regenerative medicine may enhance the efficacy of these approaches and improve pregnancy outcomes. This review explores how integrating these strategies can potentially transform the lives of couples experiencing repeated pregnancy loss or implantation failure, providing hope for improved treatment success. Precision and regenerative medicine represent a new frontier for managing RPL and RIF, offering promising solutions.

Transcriptome-wide N6-methyladenosine modification profiling of long non-coding RNAs in patients with recurrent implantation failure

N6-methyladenosine (m6A) is involved in most biological processes and actively participates in the regulation of reproduction. According to recent research, long non-coding RNAs (lncRNAs) and their m6A modifications are involved in reproductive diseases. In the present study, using m6A-modified RNA immunoprecipitation sequencing (m6A-seq), we established the m6A methylation transcription profiles in patients with recurrent implantation failure (RIF) for the first time. There were 1443 significantly upregulated m6A peaks and 425 significantly downregulated m6A peaks in RIF. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses revealed that genes associated with differentially methylated lncRNAs are involved in the p53 signalling pathway and amino acid metabolism. The competing endogenous RNA network revealed a regulatory relationship between lncRNAs, microRNAs and messenger RNAs. We verified the m6A methylation abundances of lncRNAs by using m6A-RNA immunoprecipitation (MeRIP)-real-time polymerase chain reaction. This study lays a foundation for further exploration of the potential role of m6A modification in the pathogenesis of RIF.

FANCD2 as a ferroptosis-related target for recurrent implantation failure by integrated bioinformatics and Mendelian randomization analysis

Despite advancements in assisted reproductive technology, recurrent implantation failure (RIF) remains a challenge. Endometrial factors, including ferroptosis and immunity, may contribute to this issue. This study integrated bioinformatics analysis and Mendelian randomization (MR) to investigate the expression and significance of DEFRGs in RIF. We intersected 484 ferroptosis-associated genes with 515 differentially expressed genes (DEGs) to identify key DEFRGs. Subsequent analyses included enrichment analysis, molecular subtype identification, machine learning model development for biomarker discovery, immune cell infiltration assessment, single-cell RNA sequencing, and MR to explore the causal relationships of selected genes with RIF. In this study, we identified 11 differentially expressed ferroptosis-related genes (DEFRGs) between RIF and healthy individuals. Cluster analysis revealed two distinct molecular subtypes with different immune profiles and DEFRG expressions. Machine learning models highlighted MUC1, GJA1 and FANCD2 as potential diagnostic biomarkers, with high accuracy in RIF prediction. Single-cell analysis further revealed the cellular localization and interactions of DEFRGs. MR suggested a protective effect of FANCD2 against RIF. Validation in RIF patients confirmed the differential expression of key DEFRGs, consistent with bioinformatics findings. This comprehensive study emphasize the significant role of DEFRGs in the pathogenesis of RIF, suggesting that modulating these genes could offer new avenues for treatment. The FANCD2 is a potential gene contributing to RIF pathogenesis through a non-classical ferroptosis-dependent pathway, providing a foundation for personalized therapeutic strategies in RIF management.

APOE-E4 allele as a potential marker for implantation failure: A comparison between fertile women, ART success and RIF patients

OBJECTIVE

Apolipoprotein E (APOE) is the most important precursor for the production of steroid hormones and is also involved in regulating the function of steroid hormones, hence playing a significant role in reproductive processes. So, APOE gene expression may be correlated with the implantation process. This study tries to make a better clarification of the correlation between APOE gene polymorphisms and recurrent implantation failure (RIF), where we compared the frequency of APOE polymorphisms in RIF patients, assisted reproductive treatment (ART) success cases and fertile women.

METHOD

In all, 100 women with successful ART who got pregnant (fetal heart rate positive) in their first or second cycle of in vitro fertilization or intracytoplasmic sperm injection, 100 infertile RIF cases, and 100 normal fertile control cases with at least one live birth were included in present study. Following DNA extraction, genotypes were determined through polymerase chain reaction-restriction fragment length polymorphism method using HhaI restriction enzyme. Finally, statistical analysis was performed by chi-squared (χ2) test in SPSS software (P < 0.05).

RESULTS

The RIF group showed significantly higher frequency for E3/E4 genotype (29%) compared with the other two control groups (fertile = 15%, ART success [ART+] = 13%) (P = 0.007). There was also a significantly higher frequency of the E4 allele in the RIF group (14.5%) compared with both of the control groups (fertile = 7.5%, ART+ = 6.5%) (P = 0.018).

CONCLUSION

APOE4 is correlated with recurrent failure in the process of embryo implantation and, accordingly, it may potentially be considered a possible risk factor to the implantation process. The presence of E4 can be proposed as a predictive indicator in determining the results of assisted reproductive techniques.

Impact of Diagnosis and Treatment of Chronic Endometritis on Outcomes Before Starting Assisted Reproductive Technology: A Retrospective Study

This study aimed to investigate the effect of diagnosis and treatment of chronic endometritis (CE) on the outcome of assisted reproductive technology (ART) with or without repeated implantation failure (RIF). This retrospective analysis included patients who underwent pathological examination for diagnosis of CE at Yamagata University Hospital. The examination was performed for all patients planned for ART with or without RIF. Patients who were examined within 6 months of the first oocyte retrieval or embryo transfer were included. We counted the number of CD138-positive cells within the endometrial stroma in patients' specimens and analyzed the patients' clinical information. Clinical rates of pregnancy and implantation were determined. A total of 80 women met the inclusion criteria: 13 CE-negative patients (17.3%) and 67 CE-positive patients (83.7%). A significant decrease was noted in the CD138-positive cell count between the first biopsy and second biopsy after CE treatment (p < 0.001). In addition, no significant differences were noted in ongoing pregnancy rates between the CE-negative patients and those who underwent CE treatment. The CD138-positive cell counts at first biopsy tended to be lower in each pregnancy group than in the non-pregnancy group. For patients planned to undergo ART, examination for diagnosis of CE with or without RIF could be considered. Pathological CD138-positive cell counts were considered useful for CE diagnosis and treatment decision-making. The study findings suggest the efficacy of antimicrobial agents in CE treatment, contributing to improved pregnancy outcomes.

Efficacy of intrauterine autologous blood cell derivatives in enhancing endometrial thickness and IVF outcomes for women with recurrent implantation failure: a retrospective cohort study

PURPOSE

The purpose of this study was to determine the effects of intrauterine infusion of autologous blood cell derivative (ABCD) on endometrial thickness and pregnancy outcomes in a group of patients who underwent IVF with recurrent implantation failure (RIF) and who had either a normal endometrium or thin endometrium.

METHODS

This retrospective study included 63 patients who experienced RIF at the Department of Reproductive Medicine and Surgery, KMC, Manipal, between January 2021 and March 2024 and who received three doses of intrauterine ABCD infusion to prepare the endometrium for frozen embryo transfer (FET).

RESULTS

We enrolled 63 RIF patients, 30 with a normal endometrium (NEM) and 33 with a thin endometrium (TEM). The endometrial thickness (EMT) significantly increased across all the groups. After 3 cycles of intrauterine ABCD infusion, the mean increases in EMT in the NEM and TEM groups were 0.77 mm and 1.36 mm, respectively, which were statistically significant. Among the 62 completed FET cycles, 40.3% were positive for beta-hCG. The clinical pregnancy rate was 33.8% (40% in the NEM group, 28.1% in the TEM group), and the live birth rate was 24.2% (30% in the NEM group, 18.8% in the TEM group). A total of 9.7% of pregnancies had spontaneous miscarriages. Moreover, the EMT did not differ between the pregnant and nonpregnant groups.

CONCLUSION

Intrauterine ABCD infusion improves the pregnancy outcomes of patients with RIF, regardless of the EMT. The results of this study revealed that endometrial receptivity improved significantly along with the EMT.

Integrated transcriptomic analysis reveals dysregulated immune infiltration and pro-inflammatory cytokines in the secretory endometrium of recurrent implantation failure patients

Recurrent implantation failure (RIF) is a leading impediment to assisted reproductive technology, yet the underlying pathogenesis of RIF remains elusive. Recent studies have sought to uncover novel biomarkers and etiological factors of RIF by profiling transcriptomes of endometrial samples. Nonetheless, the inherent heterogeneity among published studies and a scarcity of experimental validations hinder the identification of robust markers of RIF. Hence, we integrated six publicly accessible datasets with 209 samples, including microarray profiles of endometrial samples in the secretory phase. After removing batch effects, we identified 175 differentially expressed genes. Gene set enrichment analysis identified dysregulation of immunological pathways in RIF. We also observed altered immune infiltration and pro-inflammatory cytokines in RIF. Protein-protein interaction network analysis identified ten hub genes, representing two co-expression modules significantly related to RIF. Knockdown of ENTPD3, one of the hub genes, promoted the epithelial-mesenchymal transition process and resulted in elevated levels of pro-inflammatory cytokines. Collectively, our study reveals abnormal gene expressions involving the regulation of epithelial-mesenchymal transition and immune status in RIF, providing valuable insights into its pathogenesis.

Impact of Hysteroscopic Instillation of Autologous Platelet-Rich Plasma on Pregnancy Outcomes in Patient With Recurrent Implantation Failure: A Case Report

Recent advancements in assisted reproductive technology (ART) have enabled couples to achieve pregnancy, who were previously unable to conceive. However, recurrent implantation failure (RIF) remains a significant challenge. This case study exhibits the effective use of hysteroscopic-guided platelet-rich plasma (PRP) instillation in the treatment of a female patient aged 33 who was nulliparous and diagnosed with RIF and a thin endometrium, which resulted in primary infertility. The couple had a history of 10 years of infertility and had previously undergone ART procedures, including intrauterine insemination (IUI) and intracytoplasmic sperm injection (ICSI), which failed. The female partner was diagnosed with a thin endometrium (<7 mm) and underwent hysteroscopy, revealing no other significant intrauterine pathologies. Following hormonal treatment and ovum pick-up, hysteroscopic PRP was administered, resulting in improved endometrial thickness (ET) and successful embryo implantation, as evidenced by a positive serum β-hCG level of 1470 mIU/mL. This case demonstrates the hysteroscopic injection of PRP's potential for increasing endometrial receptivity and enhancing ART outcomes in women with RIF due to thin endometrium, making it a promising alternative to conventional therapies.

Subcutaneous G-CSF administration improves IVF outcomes in patients with recurrent implantation failure presenting a KIR/HLA-C mismatch

RESEARCH QUESTION

Despite advances in assisted reproductive technologies, many blastocysts are lost unexpectedly during implantation. Alterations in maternal immune tolerance towards fetal antigens may contribute to adverse IVF outcomes. The purpose of this study is to evaluate whether administering Granulocyte Colony-Stimulating Factor (G-CSF) to couples with a Human Leukocyte Antigen/Killer-Cell Immunoglobulin-Like Receptor (HLA/KIR) mismatch could positively modulate the implantation process in patients with recurrent implantation failure (RIF). A KIR/HLA-C mismatch occurs when the interaction between KIRs and HLA-C causes an inhibition of NK cells, which may result in reduced G-CSF secretion leading to impaired placentation and increased risk of miscarriage, pre-eclampsia and fetal growth restriction.

DESIGN

A retrospective monocentric cohort study conducted at the IVI Clinic in Rome, including women with a history of at least two failed blastocyst transfers. Couples underwent KIR and HLA-C testing. Couples with a KIR/HLA-C mismatch received G-CSF subcutaneously up to week nine of gestation. The mismatch included cases with inhibitory KIR genotypes and HLA-C2C2 females with HLA-C1C1, or C1C2 males or HLA-C1C2 females with male HLA-C2C2. The reproductive outcomes were assessed, and the logistic regression models controlled for potential confounders affecting IVF outcomes.

RESULTS

79 patients with RIF and a KIR/HLA-C mismatch were included in the study. 30 patients were administered G-CSF, and 49 received no treatment. In the univariate analysis, no statistically significant differences were reported in the reproductive outcomes after IVF between the women treated with G-CSF and the control group. However, the logistic regression analysis that controlled for confounding factors showed that patients treated with subcutaneous G-CSF had statistically significant higher ongoing-pregnancy (aOR=3.808) and live-birth (aOR=4.998) rates, and a lower miscarriage rate (aOR=0.057). No statistically significant differences were found in other reproductive outcomes.

CONCLUSION

The use of subcutaneous G-CSF in patients with a KIR/HLA-C mismatch undergoing IVF may reduce miscarriage and improve live-birth rates. G-CSF may modulate NK-mediated immune mechanisms and improve trophoblast invasion and development. Randomized trials are warranted to validate these findings and enhance the chances of successful pregnancies in couples with an immunological mismatch.

Metabolomic profiling of embryo culture media in patients with repeated implantation failure during assisted reproductive technology cycles

OBJECTIVE

This study investigated the metabolic status of the spent culture media from embryos of patients with repeated implantation failure (RIF) undergoing in vitro fertilization-intracytoplasmic sperm injection cycles in comparison with the embryos from healthy fertile women.

METHODS

Metabolite levels in spent culture media were assessed and compared between embryos from RIF patients (n=35) and oocyte donors as controls (n=15). Protein levels of insulin-like growth factor 1 (IGF-1) were determined using Western blotting. Concentrations of glucose, pyruvate, and lactate were measured using spectrophotometry. Ionic colorimetric assay kits were utilized to analyze the concentrations of sodium, chloride, calcium, and magnesium ions. High-performance liquid chromatography was employed to measure the concentrations of glutamic acid, aspartic acid, methionine, phenylalanine, and histidine.

RESULTS

Glucose consumption and lactate secretion were higher in the control group than in the RIF group. The magnesium concentration was significantly higher in the control group than in the RIF group, but glutamic acid and aspartic acid concentrations were lower in the control group than in the RIF patients (p<0.05). The levels of IGF-1, sodium, calcium, chloride, methionine, histidine, and phenylalanine did not show statistically significant differences between the two groups.

CONCLUSION

The metabolic profile of the culture medium of the embryos in the RIF group differed from that of the control group. These findings suggest potential factors that may affect implantation capacity in RIF patients and provide a new perspective on embryo selection.

From bench to in silico and backwards: What have we done on genetics of recurrent pregnancy loss and implantation failure and where should we go next?

Human reproduction goes through many challenges to its success and in many cases it fails. Cases of pregnancy loss are common outcomes for pregnancies, and implantation failures (IF) are common in assisted reproduction attempts. Although several risk factors have already been linked to adverse outcomes in reproduction, many cases remain without a definitive cause. Genetics of female reproduction is a field that may bring some pieces of this puzzle; however, there are no well-defined genes that might be related to the risk for recurrent pregnancy loss (RPL) and IF. Here, we present a literature review of the studies of genetic association in RPL and IF carried out in the Brazilian population and complemented with a database search to explore genes previously related to RPL and IF, where a search for genes previously involved in these conditions was performed in OMIM, HuGE, and CTD databases. Finally, we present the next steps for reproductive genetics investigation, through genomic sequencing analyses and discuss future plans in the study of RPL genetics. The combined strategy of looking for literature and databases is useful to raise hypotheses and to identify underexplored genes related to RPL and IF.

Predicting risk of endometrial failure: a biomarker signature that identifies a novel disruption independent of endometrial timing in patients undergoing hormonal replacement cycles

OBJECTIVE

To propose a new gene expression signature that identifies endometrial disruptions independent of endometrial luteal phase timing and predicts if patients are at risk of endometrial failure.

DESIGN

Multicentric, prospective study.

SETTING

Reproductive medicine research department in a public hospital affiliated with private fertility clinics and a reproductive genetics laboratory.

PATIENTS

Caucasian women (n = 281; 39.4 ± 4.8 years old with a body mass index of 22.9 ± 3.5 kg/m2) undergoing hormone replacement therapy between July 2018 and July 2021. Endometrial samples from 217 patients met RNA quality criteria for signature discovery and analysis.

INTERVENTION(S)

Endometrial biopsies collected in the mid-secretory phase.

MAIN OUTCOME MEASURE(S)

Endometrial luteal phase timing-corrected expression of 404 genes and reproductive outcomes of the first single embryo transfer (SET) after biopsy collection to identify prognostic biomarkers of endometrial failure.

RESULTS

Removal of endometrial timing variation from gene expression data allowed patients to be stratified into poor (n = 137) or good (n = 49) endometrial prognosis groups on the basis of their clinical and transcriptomic profiles. Significant differences were found between endometrial prognosis groups in terms of reproductive rates: pregnancy (44.6% vs. 79.6%), live birth (25.6% vs. 77.6%), clinical miscarriage (22.2% vs. 2.6%), and biochemical miscarriage (20.4% vs. 0%). The relative risk of endometrial failure for patients predicted as a poor endometrial prognosis was 3.3 times higher than those with a good prognosis. The differences in gene expression between both profiles were proposed as a biomarker, coined the endometrial failure risk (EFR) signature. Poor prognosis profiles were characterized by 59 upregulated and 63 downregulated genes mainly involved in regulation (17.0%), metabolism (8.4%), immune response, and inflammation (7.8%). This EFR signature had a median accuracy of 0.92 (min = 0.88, max = 0.94), median sensitivity of 0.96 (min = 0.91, max = 0.98), and median specificity of 0.84 (min = 0.77, max = 0.88), positioning itself as a promising biomarker for endometrial evaluation.

CONCLUSION(S)

The EFR signature revealed a novel endometrial disruption, independent of endometrial luteal phase timing, present in 73.7% of patients. This EFR signature stratified patients into 2 significantly distinct and clinically relevant prognosis profiles providing opportunities for personalized therapy. Nevertheless, further validations are needed before implementing this gene signature as an artificial intelligence (AI)-based tool to reduce the risk of patients experiencing endometrial failure.