Implantation failure: molecular mechanisms and clinical treatment

Evaluation of endometrial receptivity in recurrent pregnancy loss and recurrent implantation failure

Objective

The cause of implantation defects in patients with recurrent implantation failure (RIF) and recurrent pregnancy loss (RPL) has not been clearly established. We aimed to evaluate the immunohistochemical changes in HOXA-11, β1 integrin, focal adhesion kinase (FAK), cluster of differentiation 44 (CD44), and extracellular matrix protein 1 (ECM1) molecules during the receptive endometrial period in patients with RIF and RPL.

Materials and Methods

This study was retrospectively conducted at a university hospital. After the exclusion of cases with pathology that may cause a change in the level of receptors in the endometrium, biopsies performed during the receptive period were selected, and the patients were categorized into RPL (n=15), RIF (n=16), control (n=16) groups. All preparations were immunohistochemically stained for HOXA-11, β1 integrin, FAK, CD44, and ECM1.

Results

HOXA-11 and β1 Integrin expression changes were similar between the RIF and control groups. However, FAK expression was significantly increased in the RIF group (p<0.01). Additionally, ECM1 and CD44 expressions were significantly decreased in the RIF group compared with the control group (p<0.01). There was no significant difference in the endometrial staining of HOXA-11, FAK, and ECM1 in patients with a history of RPL. However, β1 Integrin and CD44 levels were significantly decreased in the RPL group compared with the control group (p<0.05).

Conclusion

Implantation is a complex process, and altered adhesion mechanisms involved in endometrial receptivity may be related to defective implantation in patients with RIF and RPL. Among the adhesion molecules, the expression of CD44, β1 integrin, FAK, and ECM1 molecules varies in inappropriate implantation compared with the normal population.

Effect of endometrial biopsy method on ribonucleic acid quality and gene expression analysis in patients with leiomyoma

Objective

To compare ribonucleic acid (RNA) quantity and purity in tissue collected with different endometrial sampling methods to establish the optimal tool for use in endometrial gene expression studies.

Design

Observational study.

Setting

University hospital.

Patients

Fourteen patients with submucosal leiomyomas.

Interventions

Unguided biopsies were obtained using a low-pressure suction device before hysteroscopy from 14 patients with submucosal leiomyomas followed by guided biopsy with a resectoscope loop. Fifty-seven samples were collected: 25 obtained using a suction device and 32 with a loop.

Main Outcome Measures

Total biopsy weight, RNA purity, and RNA yield for each collection method. After complementary deoxyribonucleic acid synthesis, HOXA10 expression was measured by quantitative polymerase chain reaction in the endometrium overlying and remote from the leiomyoma, as similar expression throughout the cavity was a prerequisite for the use of unguided biopsy method.

Results

The median weight of the samples was significantly larger when obtained with the low-pressure suction device than with the resectoscope loop (153 vs. 20 mg). The RNA yield was similar (suction curette, 1,625 ng/mg; resectoscope loop, 1,779 ng/mg). The A260-to-A280 ratio was satisfactory for 94.7 % of the samples, with no difference between the groups. The endometrial expression of HOXA10 was similar in areas overlying the leiomyoma compared with that in remote endometrial sites (2-ΔCt = 0.0224 vs. 0.0225).

Conclusions

Low-pressure endometrial suction devices provide tissue samples with acceptable RNA purity and quantity for gene expression studies. The expression of HOXA10 did not differ between endometrial sampling sites even in the presence of leiomyomas.

lncRNA TTTY14 participates in the progression of repeated implantation failure by regulating the miR-6088/SEMA5A axis

PURPOSE

To identify potential biomarkers and the molecular mechanisms associated with repeated implantation failure (RIF), three microarray datasets, GSE71331 (lncRNA + mRNA), GSE111974 (lncRNA + mRNA), and GSE71332 (miRNA), were retrieved from the Gene Expression Omnibus (GEO) database.

METHODS

The differentially expressed mRNAs (DEMs), lncRNAs (DElncRNAs), and miRNAs (DEmiRNAs) between normal control samples (C group) and RIF samples (RIF group) were identified, and then a module partition analysis was performed based on weighted correlation network analysis (WGCNA). Following enrichment analysis of the genes, the lncRNA-miRNA-mRNA interactions (ceRNA) were examined. The mRNAs in the ceRNA network were evaluated using the GSE58144 dataset. Finally, the key RNAs were verified using reverse transcription-quantitative polymerase chain reaction (RT-qPCR).

RESULTS

Fifty-three DEmiRNAs, 327 DEMs, and 13 DElncRNAs were identified between the C and RIF groups. According to WGCNA, the magenta module was positively correlated with RIF disease status. The lncRNA-mRNA interaction analysis based on genes in the magenta module revealed the intersecting lncRNAs, including peptidylprolyl isomerase E-like pseudogene (PPIEL) and the testis-specific transcript, y-Linked 14 (TTTY14); these lncRNAs are mainly involved in functions, such as plasma membrane organization. The ceRNA network analysis revealed several interactions, such as TTTY14-miR-6088-semaphorin 5 A (SEMA5A). Finally, SEMA5A and the zinc finger protein 555 (ZNF555) were identified to be significantly upregulated in the RIF group compared with those in the C group in the GSE58144 dataset. The RT-qPCR results aligned with the above results.

CONCLUSIONS

Overall, TTTY14, ZNF555, SEMA5A, PPIEL, and miR-6088 could serve as novel biomarkers of RIF.

Unveiling the Role of Endometrial CD-138: A Comprehensive Review on Its Significance in Infertility and Early Pregnancy

This review comprehensively examines the role of endometrial CD-138 (syndecan-1) in the context of infertility and early pregnancy. The endometrium, a dynamic tissue responsive to hormonal cues, plays a central role in fertility, and understanding the molecular intricacies governing its function is crucial. CD-138, a cell surface proteoglycan, emerges as a critical player expressed by various endometrial cell types. Our exploration encompasses a brief overview of the endometrium, introducing CD-138 as a significant molecular entity. The rationale for the review underscores the importance of elucidating endometrial factors in fertility and addresses existing knowledge gaps related to CD-138. Throughout the review, we unravel the multifaceted nature of CD-138 and its involvement in infertility, highlighting its potential as a diagnostic marker. Furthermore, insights into CD-138's role during early pregnancy, including trophoblast-endothelial interactions, are discussed. In conclusion, the findings underscore the clinical implications of CD-138, suggesting its utility in diagnostics and offering prospects for targeted therapeutic interventions. The identified knowledge gaps propel future research directions, promising to deepen our understanding of this enigmatic molecule and its transformative potential in reproductive medicine.

Uterine Arteries Resistance in Pregnant Women with Gestational Diabetes Mellitus, Diabetes Mellitus Type 1, Diabetes Mellitus Type 2, and Uncomplicated Pregnancies

BACKGROUND

The examination of the uterine arteries using Doppler in the first trimester of pregnancy serves as a valuable tool for evaluating the uteroplacental circulation. Diabetes mellitus is associated with altered placental implantation and pregnancy-related pathologies, such as preeclampsia. The aim of this study was to compare the uterine arteries' pulsatility indices (UtA PI) in women with diabetes mellitus type 1 (DM1), diabetes mellitus type 2 (DM2), gestational diabetes mellitus (GDM), and uncomplicated pregnancies.

METHODS

This was a retrospective case-control trial including pregnant women with DM1, DM2, GDM, and uncomplicated pregnancies, presenting for first-trimester ultrasound screening in two tertiary university hospitals between 2013 and 2023. The first-trimester UtA pulsatility index (PI), expressed in multiples of medians (MoMs), was compared between the four groups.

RESULTS

Out of 15,638 pregnant women, 58 women with DM1, 67 women with DM2, 65 women with GDM, and 65 women with uncomplicated pregnancies were included. The mean UtA PI were 1.00 ± 0.26 MoMs, 1.04 ± 0.32 MoMs, 1.02 ± 0.31 MoMs, and 1.08 ± 0.33 MoMs in pregnant women with DM1, DM2, GDM, and uncomplicated pregnancies, respectively (p > 0.05).

CONCLUSIONS

Potential alterations in the implantation of the placenta in pregnant women with diabetes were not displayed in the first-trimester pulsatility indices of the uterine arteries, as there were no changes between the groups.

Epigenetic Dysregulation in Endometriosis: Implications for Pathophysiology and Therapeutics

Endometriosis is a prevalent gynecological condition associated with pelvic pain and infertility. Despite more than a century of research, the etiology of endometriosis still eludes scientific consensus. This lack of clarity has resulted in suboptimal prevention, diagnosis, and treatment options. Evidence of genetic contributors to endometriosis is interesting but limited; however, significant progress has been made in recent years in identifying an epigenetic role in the pathogenesis of endometriosis through clinical studies, in vitro cell culture experiments, and in vivo animal models. The predominant findings include endometriosis-related differential expression of DNA methyltransferases and demethylases, histone deacetylases, methyltransferases, and demethylases, and regulators of chromatin architecture. There is also an emerging role for miRNAs in controlling epigenetic regulators in the endometrium and endometriosis. Changes in these epigenetic regulators result in differential chromatin organization and DNA methylation, with consequences for gene expression independent of a genetic sequence. Epigenetically altered expression of genes related to steroid hormone production and signaling, immune regulation, and endometrial cell identity and function have all been identified and appear to play into the pathophysiological mechanisms of endometriosis and resulting infertility. This review summarizes and critically discusses early seminal findings, the ever-growing recent evidence of epigenetic contributions to the pathophysiology of endometriosis, and implications for proposed epigenetically targeted therapeutics.

Infertility in patients with uterine fibroids: a debate about the hypothetical mechanisms

Fibroids are benign tumours of the myometrium and are the most common gynaecologic abnormality. Although most fibroids are asymptomatic, they can cause symptoms like heavy menstrual bleeding, pelvic pain, sexual dysfunction, pressure complaints, and infertility. The association between fibroids and infertility has been debated for decades. It is generally acknowledged that the closer the fibroid is to the uterine cavity and the endometrium lining, the more unfavourable effect it might have on fertility, reducing the odds for successful implantation and gestation. Based on the limited available literature, we propose and discuss seven hypotheses on the underlying mechanism by which fibroids may reduce fertility. (i) Fibroids can cause sexual dysfunction, as fibroids can cause dyspareunia, pelvic pain, and prolonged and heavy menstrual bleeding, which could interfere with sexual arousal and as a consequence the frequency of intercourse, resulting in a reduced probability of conception. (ii) Mechanical compression by fibroids on theinterstitial part of the fallopian tubes or deformation of uterine cavity could disturb oocyte and sperm transport. (iii) Fibroids can disturb peristalsis of the junctional zone in the myometrium, which could negatively influence oocyte and sperm transport as well as implantation. In addition, fibroids could induce a detrimental environment for implantation in other ways, by: (iv) changing the vagino-uterine microbiome; (v) disturbing the levels of inflammation and autophagy; (vi) inducing molecular changes in the endometrium; and (vii) inducing aberrant angiogenesis and altering the endometrial blood supply. After the discussion of these hypotheses, the implication of the influence of fibroids on early pregnancy loss is discussed. Surgical fibroid treatment is not tailored nor focussed on the pathophysiology of the fibroid; consequently it may be accompanied by recurrence of fibroids and risks of complications. Unravelling the pathogenic mechanisms about how fibroids influence fertility is essential to evolve classic surgical fibroid treatment. Instead of treatment of fibroid-related symptoms, the research should supports development of fibroid-targeted (pharmaceutical) treatment that is compatible with an active wish to become pregnant.

The Role of Dydrogesterone in the Management of Luteal Phase Defect: A Comprehensive Review

The luteal phase of the menstrual cycle is a pivotal period characterized by hormonal intricacies that lay the foundation for successful embryo implantation and early pregnancy development. Luteal phase defect (LPD), marked by abnormalities in luteal function, presents challenges that can impede reproductive outcomes. This comprehensive review article explores the role of dydrogesterone in LPD management, elucidating its mechanisms of action, evidence of efficacy, safety profile, and potential in combination therapies. Dydrogesterone, a synthetic progestogen, closely mirrors natural progesterone's actions, effectively supplementing the luteal phase and enhancing endometrial receptivity. Clinical studies demonstrate improved pregnancy rates, extended luteal phase support, and enhanced reproductive outcomes with dydrogesterone supplementation. Its favorable safety profile, minimal side effects, and reduced risk of unwanted hormonal effects contribute to its appeal. Furthermore, dydrogesterone's inclusion in international guidelines solidifies its importance in LPD management. Combination therapies, leveraging synergistic effects, offer a comprehensive approach. As gaps in knowledge persist, future research directions and personalized treatment strategies pave the way for a future where dydrogesterone stands as a beacon of hope in conquering the challenges of LPD and achieving successful reproductive outcomes.

Implantation in the lower half of the uterine cavity and decreased trophoblastic thickness can predict subsequent miscarriage: a prospective cohort study

Abstract

Embryo implantation is vital for successful conception but remains to be fully understood. Trophoblast invasion is key for implantation, with anchorage and depth of placentation determined by its extent. There is a dearth of synchronous information regarding IVF, implantation site, and trophoblastic thickness (TT). Our aim was to determine whether pregnancy implantation site and TT, had an impact on outcomes of IVF pregnancies. This prospective observational study was undertaken at a tertiary referral UK fertility unit over 14 months, collecting data on implantation site and TT from three-dimensional (3D) images of the uterus following early pregnancy scan. Of the 300 women recruited, 277 (92%) had live births, 20 (7%) miscarried, 2 (0.7%) had stillbirths, and 1 (0.3%) had a termination. Significantly more pregnancies that resulted in miscarriage (7/20, 35%) were located in the lower uterine cavity when compared to ongoing pregnancies (15/277, 5%) (P < 0.01). TT was significantly higher in ongoing pregnancies when compared with those who miscarried (7.2 mm vs 5.5 mm; P < 0.01). Implantation in the lower half of the uterine cavity and decreased TT are significantly associated with an increased rate of miscarriage. Identification of those at risk should prompt increased monitoring with the aim of supporting these pregnancies.

Lay summary

Implantation of an embryo in the womb is vital for a successful pregnancy. We wanted to find out whether findings on an ultrasound scan in early pregnancy had an impact on outcomes of IVF pregnancies. Three hundred women were recruited to the study, 277 (92%) had live births and unfortunately 20 (7%) had a miscarriage, 2 (0.7%) had stillbirths, and 1 (0.3%) had a termination. Many more of the pregnancies that miscarried implanted in the lower part of the womb. The thickness of the infiltration of the pregnancy into the womb was significantly higher in the ongoing pregnancies. We concluded that implantation in the lower half of the womb and reduced infiltration of the pregnancy seen on scan are associated with an increased rate of miscarriage. We propose that when we identify those at risk, we should increase monitoring, with the aim of supporting these pregnancies.

The impact of endometrial scratch performed in mid-luteal phase on the endometrium whole genome transcriptomic profiles in following menstrual cycle

The value of endometrial scratch in women with recurrent embryo transfer has been controversial. Endometrial scratch is often performed in the mid-luteal phase of the cycle preceding embryo transfer but there is little scientific evidence if it affects the whole genome transcriptomic profile of peri-implantation endometrium in the following cycle. A prospective longitudinal cohort study was conducted in a university assisted reproductive unit. A total of eight women with recurrent implantation failure (RIF) were included. Each participant had endometrial biopsy twice, first biopsy on day LH + 7 in natural cycle and second on day LH + 7 of the following cycle. R package was used to identify differentially expressed genes between the sample and enriched gene ontology. However, the paired sample showed no significant difference, neither known endometrial receptive gene set nor other genes, before and after the endometrial scratch. It suggests that endometrial scratch performed during previous mid-luteal phase did not affect the transcriptomic profiles of endometrium on day LH + 7 in women with RIF.

Deciphering a shared transcriptomic regulation and the relative contribution of each regulator type through endometrial gene expression signatures

BACKGORUND

While various endometrial biomarkers have been characterized at the transcriptomic and functional level, there is generally a poor overlap among studies, making it unclear to what extent their upstream regulators (e.g., ovarian hormones, transcription factors (TFs) and microRNAs (miRNAs)) realistically contribute to menstrual cycle progression and function. Unmasking the intricacies of the molecular interactions in the endometrium from a novel systemic point of view will help gain a more accurate perspective of endometrial regulation and a better explanation the molecular etiology of endometrial-factor infertility.

METHODS

An in-silico analysis was carried out to identify which regulators consistently target the gene biomarkers proposed in studies related to endometrial progression and implantation failure (19 gene lists/signatures were included). The roles of these regulators, and of genes related to progesterone and estrogens, were then analysed in transcriptomic datasets compiled from samples collected throughout the menstrual cycle (n = 129), and the expression of selected TFs were prospectively validated in an independent cohort of healthy participants (n = 19).

RESULTS

A total of 3,608 distinct genes from the 19 gene lists were associated with endometrial progression and implantation failure. The lists' regulation was significantly favoured by TFs (89% (17/19) of gene lists) and progesterone (47% (8 /19) of gene lists), rather than miRNAs (5% (1/19) of gene lists) or estrogen (0% (0/19) of gene lists), respectively (FDR < 0.05). Exceptionally, two gene lists that were previously associated with implantation failure and unexplained infertility were less hormone-dependent, but primarily regulated by estrogen. Although endometrial progression genes were mainly targeted by hormones rather than non-hormonal contributors (odds ratio = 91.94, FDR < 0.05), we identified 311 TFs and 595 miRNAs not previously associated with ovarian hormones. We highlight CTCF, GATA6, hsa-miR-15a-5p, hsa-miR-218-5p, hsa-miR-107, hsa-miR-103a-3p, and hsa-miR-128-3p, as overlapping novel master regulators of endometrial function. The gene expression changes of selected regulators throughout the menstrual cycle (FDR < 0.05), dually validated in-silico and through endometrial biopsies, corroborated their potential regulatory roles in the endometrium.

CONCLUSIONS

This study revealed novel hormonal and non-hormonal regulators and their relative contributions to endometrial progression and pathology, providing new leads for the potential causes of endometrial-factor infertility.

Hyperandrogenism and Its Possible Effects on Endometrial Receptivity: A Review

Endometrial receptivity is a state of the endometrium defined by its readiness for embryo implantation. When the receptivity of the endometrium is impaired due to hyperandrogenism or androgen excess, this condition can lead to pregnancy loss or infertility. Hyperandrogenism encompasses a wide range of clinical manifestations, including polycystic ovary syndrome (PCOS), idiopathic hirsutism, hirsutism and hyperandrogaenemia, non-classical congenital adrenal hyperplasia, hyperandrogenism, insulin resistance, acanthosis nigricans (HAIR-AN), ovarian or adrenal androgen-secreting neoplasms, Cushing's syndrome, and hyperprolactinaemia. Recurrent miscarriages have been shown to be closely related to elevated testosterone levels, which alter the endometrial milieu so that it is less favourable for embryo implantation. There are mechanisms for endometrial receptivity that are affected by excess androgen. The HOXA gene, aVβ3 integrin, CDK signalling pathway, MECA-79, and MAGEA-11 were the genes and proteins affect endometrial receptivity in the presence of a hyperandrogenic state. In this review, we would like to explore the other manifestations of androgen excess focusing on causes other than PCOS and learn possible mechanisms of endometrial receptivity behind androgen excess leading to pregnancy loss or infertility.

Endometrial Angiogenesis of Abnormal Uterine Bleeding and Infertility in Patients with Uterine Fibroids-A Systematic Review

Uterine fibroids are the most common benign tumors in women, with abnormal uterine bleeding (AUB) as the main reported symptom. Additionally, an association between fibroids and infertility has been established, especially if the fibroid protrudes in the uterine cavity. Hormonal therapy is associated with side-effects and as well as hysterectomy, which is incompatible with a desire to conceive. To improve treatment, it is essential to unravel the etiology of fibroid-related symptoms. We aim to evaluate endometrial angiogenesis in women with fibroids, with and without AUB, and the influence of pharmaceutical therapies in these patients. Furthermore, we explore the possible role of altered angiogenesis in patients with fibroids and infertility. We performed a systematic review according to PRISMA-guidelines (PROSPERO: CRD42020169061), and included 15 eligible studies. Endometrial expression of vascular endothelial growth factor (VEGF) and adrenomedullin was increased in patients with fibroids. This suggests aberrant angiogenesis, potentially involving disturbed vessel maturation, resulting in immature and fragile vessels. Treatment with gonadotropin-releasing hormone agonist, ulipristal acetate, and continuous oral contraception pills reduced several angiogenic parameters, including VEGF. If infertile and fertile patients with fibroids were compared, a significant decreased expression of the bone morphogenetic protein/Smad-protein pathway was found, possibly caused by the increased expression of transforming growth factor-beta. For future therapeutic development, these different angiogenic pathways could be of interest as possible targets to treat fibroid-related symptoms.

Towards a Better Understanding of Endometriosis-Related Infertility: A Review on How Endometriosis Affects Endometrial Receptivity

Endometriosis is the most common cause of infertility. Endometrial receptivity has been suggested to contribute to infertility and poor reproductive outcomes in affected women. Even though experimental and clinical data suggest that the endometrium differs in women with endometriosis, the pathogenesis of impaired endometrial receptivity remains incomplete. Therefore, this review summarizes the potential mechanisms that affect endometrial function and contribute to implantation failure. Contemporary data regarding hormone imbalance, inflammation, and immunoregulatory dysfunction will be reviewed here. In addition, genetic, epigenetic, glycosylation, metabolism and microRNA in endometriosis-related infertility/subfertility will be summarized. We provide a brief discussion and perspectives on their future clinical implications in the diagnosis and therapy to improve endometrial function in affected women.

Abnormal expression of SLIT3 induces intravillous vascularization dysplasia in ectopic pregnancy

Objective

To investigate whether the morphology, capillary number, and transcriptome expression profiles of ectopic pregnancy (EP) villi differ from those of normal pregnancy (NP) villi.

Methods

Hematoxylin-eosin (HE) and immunohistochemistry (IHC) staining for CD31 were conducted to compare differences in morphology and capillary number between EP and NP villi. Differentially expressed (DE) miRNAs and mRNAs were determined from transcriptome sequencing of both types of villi and used to construct a miRNA-mRNA network, from which hub genes were identified. Candidate DE-miRNAs and DE-mRNAs were validated by quantitative reverse transcription (qRT)-PCR. Correlations were identified between the number of capillaries and serum beta human chorionic gonadotropin (β-HCG) levels and between the expression levels of hub genes associated with angiogenesis and β-HCG levels.

Results

The mean and total cross-sectional areas of placental villi were significantly increased in EP compared with NP villi. Capillary density was greatly reduced in EP villi and was positively correlated with β-HCG levels. A total of 49 DE-miRNAs and 625 DE-mRNAs were identified from the sequencing data. An integrated analysis established a miRNA-mRNA network containing 32 DE-miRNAs and 103 DE-mRNAs. Based on the validation of hub mRNAs and miRNAs in the network, a regulatory pathway involving miR-491-5p-SLIT3 was discovered, which may have a role in the development of villous capillaries.

Conclusion

Villus morphology, capillary number, and miRNA/mRNA expression profiles in villous tissues were aberrant in EP placentas. Specifically, SLIT3, which is regulated by miR-491-5p, may contribute to the regulation of villous angiogenesis and was established as a putative predictor of chorionic villus development, providing a basis for future research.

Uterine administration of C-X-C motif chemokine ligand 12 increases the pregnancy rates in mice with induced endometriosis

OBJECTIVE

To study the effect of intrauterine injection of C-X-C motif chemokine ligand 12 (CXCL12), also known as a stem cell chemoattractant (stromal cell-derived factor 1), on fertility and endometrial receptivity in mice with endometriosis.

DESIGN

Laboratory study.

SETTING

Academic Medical Center.

ANIMAL(S)

Fifty-six mice underwent chemotherapy and bone marrow transplantation. Thirty-six of these mice underwent either surgery to induce endometriosis (n = 20) or sham surgery (n = 16).

INTERVENTION(S)

Injection of CXCL12 as a potential therapeutic agent to improve fertility in endometriosis.

MAIN OUTCOME MEASURE(S)

Pregnancy rate, bone marrow-derived cell (BMDC) recruitment and endometrial receptivity markers.

RESULT(S)

The mice with or without endometriosis received a single uterine injection of either CXCL12 or placebo. Uterine injection of CXCL12 increased the pregnancy rates in a mouse model of endometriosis. Mice were euthanized after delivery, and implantation markers homeobox A11, alpha-v beta-3 integrin, and progesterone receptor were analyzed by immunohistochemistry, whereas green fluorescent protein positive BMDC recruitment was quantified by immunohistochemistry and immunofluorescence. The sham surgery groups without endometriosis had the highest cumulative pregnancy rate (100%) regardless of CXCL12 treatment. The endometriosis group treated with placebo had the lowest pregnancy rate. An increased pregnancy rate was noted in the endometriosis group after treatment with CXCL12. There was also an increase in BMDC recruitment and endometrial expression of progesterone receptor and alpha-v beta-3 integrin in the endometriosis group that received CXCL12 compared with that in the endometriosis group that received placebo.

CONCLUSION(S)

Uterine injection of CXCL12 increased the pregnancy rates in a mouse model of endometriosis. These results suggest that CXCL12 has a potential role as a therapeutic agent in women with infertility related to endometriosis and potentially other endometrial receptivity defects.

The Potential Mechanism of Zishen Yutai Pills against Threatened Abortion: An Approach Involving Network Pharmacology and Experimental Evidence

Threatened abortion (TA) is the most common complication in early pregnancy and is caused by anxiety and depressive symptoms. The Zishen Yutai Pill (ZYP) is a traditional herbal formula that is commonly used to treat TA. However, the pharmacological mechanisms underlying the effect of ZYP have yet to be elucidated. To disclose the mechanism of ZYP in the treatment of TA, first, we identified the chemical constituents of ZYP from multiple databases and then predicted the potential targets of TA by applying the GeneCards database. A protein-protein interaction (PPI) network was then constructed to allow the screening of hub targets. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGGs) enrichment analyses were also performed and the Database for Annotation Visualization and Integrated Discovery server was used to identify critical biological processes and signaling pathways. Cytoscape software was used to construct a Compound-Target-Pathway. Furthermore, we analyzed ZYP by UPLC-Q-TOF/MS, then the RU486-induced TA rat model was established, and the reliability of the network pharmacology prediction results was verified. Finally, the mechanisms responsible for the action of ZYP on TA were revealed by qRT-PCR and molecular docking. Database screening identified a total of 161 active compounds in ZYP and 324 TA-related targets. And, we identified 42 compounds from ZYP by UPLC-Q-TOF/MS. Inflammation and apoptosis were identified as the main biological processes. GO and KEGG analyses identified that the MAPK and PI3K/Akt pathways were the key functional pathways that respond to ZYP. The results showed that ZYP treatment significantly increased maternal weight, significantly increased the levels of estradiol and progesterone, and attenuated histopathological changes in a rat model of TA. Data indicated that ZYP treatment improved pregnancy outcomes in the rat model of TA. QRT-PCR data showed that ZYP reduced inflammation and apoptosis by regulating the MAPK and PI3K/Akt pathways. In addition, molecule docking results identified a range of key compounds, including Pik3a, Mapk14, Mapk1, Mapk3, Mapk8 Tnf, Il6, and Cas8. In summary, we performed network pharmacological analysis and experimental validation and identified that ZYP exerts an effect on TA by regulating the MAPK and PI3K/Akt pathways and by inhibiting the expression levels of proinflammatory cytokines and genes related to apoptosis.

Endometrial small extracellular vesicles regulate human trophectodermal cell invasion by reprogramming the phosphoproteome landscape

A series of cyclical events within the uterus are crucial for pregnancy establishment. These include endometrial regeneration following menses, under the influence of estrogen (proliferative phase), then endometrial differentiation driven by estrogen/progesterone (secretory phase), to provide a microenvironment enabling attachment of embryo (as a hatched blastocyst) to the endometrial epithelium. This is followed by invasion of trophectodermal cells (the outer layer of the blastocyst) into the endometrium tissue to facilitate intrauterine development. Small extracellular vesicles (sEVs) released by endometrial epithelial cells during the secretory phase have been shown to facilitate trophoblast invasion; however, the molecular mechanisms that underline this process remain poorly understood. Here, we show that density gradient purified sEVs (1.06-1.11 g/ml, Alix⁺ and TSG101⁺, ∼180 nm) from human endometrial epithelial cells (hormonally primed with estrogen and progesterone vs. estrogen alone) are readily internalized by a human trophectodermal stem cell line and promote their invasion into Matrigel matrix. Mass spectrometry-based proteome analysis revealed that sEVs reprogrammed trophectoderm cell proteome and their cell surface proteome (surfaceome) to support this invasive phenotype through upregulation of pro-invasive regulators associated with focal adhesions (NRP1, PTPRK, ROCK2, TEK), embryo implantation (FBLN1, NIBAN2, BSG), and kinase receptors (EPHB4/B2, ERBB2, STRAP). Kinase substrate prediction highlighted a central role of MAPK3 as an upstream kinase regulating target cell proteome reprogramming. Phosphoproteome analysis pinpointed upregulation of MAPK3 T204/T202 phosphosites in hTSCs following sEV delivery, and that their pharmacological inhibition significantly abrogated invasion. This study provides novel molecular insights into endometrial sEVs orchestrating trophoblast invasion, highlighting the microenvironmental regulation of hTSCs during embryo implantation.

Elevated histone demethylase KDM5C increases recurrent miscarriage risk by preventing trophoblast proliferation and invasion

KDM5C is a histone H3K4-specific demethylase, which has been shown to play a key role in biological disease and development. However, the role of KDM5C in trophoblasts at early pregnancy is currently unknown. Here, we showed that KDM5C was upregulated in placental trophoblasts from recurrent miscarriage (RM) patients compared with healthy controls (HCs). Trophoblast proliferation and invasion was inhibited by KDM5C overexpression and was promoted by KDM5C knockdown. Transcriptome sequencing revealed that elevated KDM5C exerted anti-proliferation and anti-invasion effects by repressing the expression of essential regulatory genes. The combination analysis of RNA-seq, ChIP-seq and CUT&Tag assay showed that KDM5C overexpression leads to the reduction of H3K4me3 on the promoters and the corresponding downregulation of expression of several regulatory genes in trophoblasts. Among these genes, TGFβ2 and RAGE are essential for the proliferation and invasion of trophoblasts. Importantly, overexpression of KDM5C by a systemically delivered KDM5C adenovirus vector (Ad-KDM5C) promoted embryo resorption rate in mouse. Our results support that KDM5C is an important regulator of the trophoblast function during early pregnancy, and suggesting that KDM5C activity could be responsible for epigenetic alterations seen RM disease.

Application of hysteroscopy in female fertility preservation

Under the background of the trend in late marriage and the relaxation of family planning policy, the reproductive behavior of women has changed and the proportion of elderly pregnant women has increased progressively year by year. Thus the female fertility preservation is particularly important. As the cradle of life, uterine malformation and uterine cavity diseases may have adverse effects on embryo implantation and development. Several common intrauterine diseases, such as uterine submucosal fibroids, endometrial polyps, intrauterine adhesions, uterine malformation, cesarean scar diverticulum, and embryo residues, may affect female fertility. Hysteroscopy is the gold standard for the diagnosis and treatment for intrauterine diseases. With the progress in science and technology, the refinement of hysteroscopy instruments and the promotion of transvaginal endoscopic technology, hysteroscopy will yield brilliant results in female fertility preservation. The knowledge and training related to hysteroscopy should be continuously promoted and popularized, so that it can be mastered by more clinicians and applied in clinical practice to benefit more female patients.

Bi-potential hPSC-derived Müllerian duct-like cells for full-thickness and functional endometrium regeneration

Stem cell-based tissue regeneration strategies are promising treatments for severe endometrial injuries. However, there are few appropriate seed cells for regenerating a full-thickness endometrium, which mainly consists of epithelia and stroma. Müllerian ducts in female embryonic development develop into endometrial epithelia and stroma. Hence, we first generated human pluripotent stem cells (hPSC)-derived Müllerian duct-like cells (MDLCs) using a defined and effective protocol. The MDLCs are bi-potent, can gradually differentiate into endometrial epithelial and stromal cells, and reconstitute full-thickness endometrium in vitro and in vivo. Furthermore, MDLCs showed the in situ repair capabilities of reconstructing endometrial structure and recovering pregnancy function in full-thickness endometrial injury rats, and their differentiation fate was revealed by single-cell RNA sequencing (scRNA-seq). Our study provides a strategy for hPSC differentiation into endometrial lineages and an alternative seed cell for injured endometrial regeneration.

High-Fat Diet and Female Fertility across Lifespan: A Comparative Lesson from Mammal Models

Female reproduction focuses mainly on achieving fully grown follicles and competent oocytes to be successfully fertilized, as well as on nourishing the developing offspring once pregnancy occurs. Current evidence demonstrates that obesity and/or high-fat diet regimes can perturbate these processes, leading to female infertility and transgenerational disorders. Since the mechanisms and reproductive processes involved are not yet fully clarified, the present review is designed as a systematic and comparative survey of the available literature. The available data demonstrate the adverse influences of obesity on diverse reproductive processes, such as folliculogenesis, oogenesis, and embryo development/implant. The negative reproductive impact may be attributed to a direct action on reproductive somatic and germinal compartments and/or to an indirect influence mediated by the endocrine, metabolic, and immune axis control systems. Overall, the present review highlights the fragmentation of the current information limiting the comprehension of the reproductive impact of a high-fat diet. Based on the incidence and prevalence of obesity in the Western countries, this topic becomes a research challenge to increase self-awareness of dietary reproductive risk to propose solid and rigorous preventive dietary regimes, as well as to develop targeted pharmacological interventions.

Loss of HOXA10 causes endometrial hyperplasia progressing to endometrial cancer

Endometrial cancer is the fourth most common malignancy in women and the precursor lesion is endometrial hyperplasia. HOXA10 is a transcription factor that plays key roles in endometrial functions such as the endowment of receptivity, embryo implantation, and trophoblast invasion. Herein, using testicular transgenesis, we developed transgenic mice that expressed a shRNA against HOXA10 and there was a nearly 70% reduction in the expression of HOXA10 in these animals. We observed that downregulation of HOXA10 led to the development of endometrial hyperplasia in the young animals (3 months), and as they aged (>1 year), most animals developed well-differentiated endometrial adenocarcinoma. In the endometrium of animals with reduced HOXA10, there was increased proliferation and elevated levels of ERα and ERβ. In parallel, there was increased expression of Wnt4 and β-Catenin, SOX9, and YAP1. We propose that chronic reduction in HOXA10 expression disrupts multiple pathways in the uterus that aids in the development of endometrial hyperplasia which progresses to endometrial cancer with age.

Shoutai Wan Improves Embryo Survival by Regulating Aerobic Glycolysis of Trophoblast Cells in a Mouse Model of Recurrent Spontaneous Abortion

Background

During embryo implantation, the blastocyst exhibits a high capacity for aerobic glycolysis, which results in a unique microenvironment of high lactate/low pH at the maternal-fetal interface. Shoutai Wan (STW) is an effective Chinese herbal formula widely used in the clinical treatment of recurrent spontaneous abortion (RSA). However, the specific molecular mechanism by which STW prevents abortion is yet to be elucidated.

Methods

Female CBA/J mice were allocated into six groups randomly and then mated with BALB/c mice as the control group, DBA/2 mice as the RSA model, CBA/J×DBA/2 mice treated with dydrogesterone as the DQYT group, or CBA/J×DBA/2 mice treated with low, medium, and high-dose STW as the STW-L, STW-M, and STW-H groups, respectively. Drug administration started 14 days before mating and ended on the 14^th day of pregnancy. The embryo loss rate of each group was calculated on day 14 of gestation, and the pregnancy outcomes of the mice in each group were observed. The mouse serum was collected to determine the levels of progesterone (P) and chorionic gonadotropin (CG). The activities of HK2, PKM2, and LDHA, the key glycolytic enzymes in each group, were detected. The expressions of lactate, ATP, HK2, PKM2, LDHA, MCT4, GLUT1, and GPR81 as well as the morphology of trophoblast cells were examined.

Results

The embryo loss rate and adverse pregnancy outcomes were significantly increased (P < 0.05) in the RSA model group. After dydrogesterone or different doses of STW treatment, the embryo loss rate and adverse pregnancy outcomes were rescued to varying degrees (P < 0.05). Interestingly, there was no significant difference among the groups in terms of serum P and CG (P < 0.05). Moreover, the activities of key glycolytic enzymes, lactate, ATP, HK2, PKM2, LDHA, MCT4, GLUT1, GPR81 protein or mRNA expression, and morphological abnormalities of trophoblast cells improved significantly in the RSA mice after dydrogesterone or different doses of STW treatment (P < 0.05).

Conclusion

STW can promote aerobic glycolysis in trophoblast cells of RSA mouse embryos, thereby improving the microenvironment of the maternal-fetal interface and enhancing embryo implantation.

The regulation and potential roles of m6A modifications in early embryonic development and immune tolerance at the maternal-fetal interface

The immune microenvironment at the maternal-fetal interface was determined by the crosstalk between the trophoblast and maternal-derived cells, which dynamically changed during the whole gestation. Trophoblasts act as innate immune cells and dialogue with maternal-derived cells to ensure early embryonic development, depending on the local immune microenvironment. Therefore, dysfunctions in trophoblasts and maternal decidual cells contribute to pregnancy complications, especially recurrent pregnancy loss in early pregnancy. Since many unknown regulatory factors still affect the complex immune status, exploring new potential aspects that could influence early pregnancy is essential. RNA methylation plays an important role in contributing to the transcriptional regulation of various cells. Sufficient studies have shown the crucial roles of N6-methyladenosine (m6A)- and m6A-associated- regulators in embryogenesis during implantation. They are also essential in regulating innate and adaptive immune cells and the immune response and shaping the local and systemic immune microenvironment. However, the function of m6A modifications at the maternal-fetal interface still lacks wide research. This review highlights the critical functions of m6A in early embryonic development, summarizes the reported research on m6A in regulating immune cells and tumor immune microenvironment, and identifies the potential value of m6A modifications in shaping trophoblasts, decidual immune cells, and the microenvironment at the maternal-fetal interface. The m6A modifications are more likely to contribute to embryogenesis, placentation and shape the immune microenvironment at the maternal-fetal interface. Uncovering these crucial regulatory mechanisms could provide novel therapeutic targets for RNA methylation in early pregnancy.

Role of endometrial microRNAs in repeated implantation failure (mini-review)

MicroRNAs (miRNAs) play various roles in the implantation and pregnancy process. Abnormal regulation of miRNAs leads to reproductive disorders such as repeated implantation failure (RIF). During the window of implantation, different miRNAs are released from the endometrium, which can potentially reflect the status of the endometrium for in vitro fertilization (IVF). The focus of this review is to determine whether endometrial miRNAs may be utilized as noninvasive biomarkers to predict the ability of endometrium to implant and provide live birth during IVF cycles. The levels of certain miRNAs in the endometrium have been linked to implantation potential and pregnancy outcomes in previous studies. Endometrial miRNAs could be employed as non-invasive biomarkers in the assisted reproductive technology (ART) cycle to determine the optimal time for implantation. Few human studies have evaluated the association between ART outcomes and endometrial miRNAs in RIF patients. This review may pave the way for more miRNA transcriptomic studies on human endometrium and introduce a specific miRNA profile as a multivariable prediction model for choosing the optimal time in the IVF cycle.

The Translational Role of miRNA in Polycystic Ovary Syndrome: From Bench to Bedside—A Systematic Literature Review

MicroRNAs (miRNAs) are small, non-coding RNAs that are essential for the regulation of post-transcriptional gene expression during tissue development and differentiation. They are involved in the regulation of manifold metabolic and hormonal processes and, within the female reproductive tract, in oocyte maturation and folliculogenesis. Altered miRNA levels have been observed in oncological and inflammatory diseases, diabetes or polycystic ovary syndrome (PCOS). Therefore, miRNAs are proving to be promising potential biomarkers. In women with PCOS, circulating miRNAs can be obtained from whole blood, serum, plasma, urine, and follicular fluid. Our systematic review summarizes data from 2010–2021 on miRNA expression in granulosa and theca cells; the relationship between miRNAs, hormonal changes, glucose and lipid metabolism in women with PCOS; and the potential role of altered miRNAs in fertility (oocyte quality) in PCOS. Furthermore, we discuss miRNAs as a potential therapeutic target in PCOS and as a diagnostic marker for PCOS.

Effects of clinical and metabolic variables and hormones on the expression of immune protein biomarkers in the endometrium of women with polycystic ovary syndrome and normal-cycling controls

BACKGROUND

Women with polycystic ovary syndrome (PCOS) are at an elevated risk of endometrial cancer, which may be associated with the continuous proliferative state caused by the interaction between hormones and metabolic factors.

OBJECTIVE

To investigate the impact of hormones and metabolic factors in the proliferation and death of endometrium during the proliferative phase.

METHODS

Cross-sectional study with 11 women with PCOS and eight normal-cycling non-PCOS controls at the Federal University of the State of Rio de Janeiro from February 2011 to June 2019. Clinical, biochemical, and hormonal data were collected to analyze their influence on the expression of biomarkers related to the endometrial tissue breakdown. Hysteroscopy and endometrial biopsies were conducted, and the endometrial samples underwent immunohistochemistry for markers of apoptosis B-cell lymphoma 2 (BCL2), cleaved caspase-3 (CASP3), fas cell surface death receptor (FAS), FAS ligand (FASLG), BCL2 associated X (BAX), marker of proliferation Ki-67 (MKI67), and cell death using terminal deoxynucleotidyl transferase dUTP nick and labeling (TUNEL).

RESULTS

CASP3 and TUNEL expressions were lower in both stroma and endometrium gland of PCOS women than in controls. MKI67 and homeostasis indexes (BCL2/BAX; FASLG/FAS) in the endometrium of the PCOS group were significantly higher. Body mass index (BMI) values were positively correlated with the expression of MKI67 and MKI67/TUNEL ratio in the endometrial stroma compartment. Fasting insulin levels were positively correlated with the expression of BCL2, and DHEA-S levels were negatively correlated with the expression of CASP3 of women with PCOS.

CONCLUSION

BMI, insulin, and DHEA-S influence the endometrial homeostasis breakdown in PCOS in the endometrium stroma.

MicroRNAs in the Regulation of Endometrial Receptivity for Embryo Implantation

Development of endometrial receptivity is crucial for successful embryo implantation and pregnancy initiation. Understanding the molecular regulation underpinning endometrial transformation to a receptive state is key to improving implantation rates in fertility treatments such as IVF. With microRNAs (miRNAs) increasingly recognized as important gene regulators, recent studies have investigated the role of miRNAs in the endometrium. Studies on miRNAs in endometrial disorders such as endometriosis and endometrial cancer have been reviewed previously. In this minireview, we aim to provide an up-to-date knowledge of miRNAs in the regulation of endometrial receptivity. Since endometrial remodelling differs considerably between species, we firstly summarised the key events of the endometrial cycle in humans and mice and then reviewed the miRNAs identified so far in these two species with likely functional significance in receptivity establishment. To date, 29 miRNAs have been reported in humans and 15 miRNAs in mice within various compartments of the endometrium that may potentially modulate receptivity; miRNAs regulating the Wnt signalling and those from the let-7, miR-23, miR-30, miR-200 and miR-183 families are found in both species. Future studies are warranted to investigate miRNAs as biomarkers and/or therapeutic targets to detect/improve endometrial receptivity in human fertility treatment.

Molecular signature of immunological mechanism behind impaired endometrial receptivity in polycystic ovarian syndrome

Objective

Despite the treatment of anovulation, infertility is still one of the main complications in PCOS women during reproductive age, which appears to be mainly due to impaired uterine receptivity. This study investigated the transcriptome profiles of endometrium in PCOS patients and healthy fertile individuals as the control group.

Methods

Total mRNA was extracted from endometrial tissues of PCOS patients (n = 12) and healthy fertile individuals (n = 10) during the luteal phase. After cDNA synthesis, PCR array was performed using Human Female Infertility RT2 Profiler PCR Array kit (Qiagen, Cat.No: PAHS-164Z) for evaluating expression of 84 genes contributing to the female infertility.

Results

PCR Array data analysis identified significantly greater expression of CSF, IL11, IL15, IL1r1, IL1b, TNF, LIF, TNFRSF10B, TGFβ, C3, ITGA4 (Cd49d), SPP1, and Calca in PCOS women than in controls (P < 0.05). However, the expression of LIFR, C2, CD55, CFD, CALCA, LAM1, LAMC2, MMP2, MMP7, MMP9, ESR, SELL, ITGB3, and VCAM1 was significantly lower in PCOS group than in controls (P < 0.05). The results revealed dysregulation of immune-inflammatory molecules, complement activation and downregulation of IGF-I as well as adhesion molecules in PCOS group.

Conclusion

The findings of this study indicated some potential causes of reduced receptivity of endometrium thus compromising the fertility in PCOS patients.

Nuclear receptor coactivator-6 is essential for the morphological change of human uterine stromal cell decidualization via regulating actin fiber reorganization

Nuclear receptor coactivator 6 (Ncoa6), a modulator of several nuclear receptors and transcription factors, is essential for the decidualization of endometrial stromal cells in mice. However, the function of Ncoa6 in the human endometrium remains unclear. We investigated its function in the decidualization of human endometrial stromal cells (HESCs) isolated from resected uteri. Knockdown of Ncoa6 was performed using two independent small interfering RNAs. Decidualization was induced in vitro via medroxyprogesterone and cyclic adenosine monophosphate. We compared decidualized cellular morphology between the Ncoa6 knockdown cells and control cells. Messenger RNA (mRNA) sequencing was performed to determine the Ncoa6 target genes in undecidualized HESCs. We found that the knockdown of Ncoa6 caused the failure of morphological changes in decidualized HESCs compared to that in the control cells. mRNA sequencing revealed that Ncoa6 regulates the expression of genes associated with the regulation of actin fibers. Ncoa6 knockdown cells failed to reorganize actin fibers during the decidualization of HESCs. Ncoa6 was shown to play an essential role in decidualization via the appropriate regulation of actin fiber regulation in HESCs. Herein, our in vitro studies revealed a part of the mechanisms involved in endometrial decidualization. Future research is needed to investigate these mechanisms in women with implantation defects.

Adenomyosis and infertility

PURPOSE

Adenomyosis is a poorly understood entity with no unified treatment protocol. It has been thought to only affect the quality of life of older women, but growing evidence is highlighting the increased frequency of adenomyosis in younger patients and its possible effects on fertility outcomes. This can have a great impact on how clinicians screen, diagnose, and treat this condition. The aim of this review is to explore the relationship between adenomyosis and infertility.

METHODS

A literature search of the keywords "adenomyosis", "infertility", "pregnancy" and "fertility" was conducted using the PubMed and Medline search engines. The articles selected were observational, systematic reviews, meta-analyses, and randomized controlled trials. The search was limited to English, abstracts were screened, and articles were selected.

RESULTS

The literature reports lower clinical pregnancy rates, lower live birth rates, higher miscarriage rates, and higher odds of adverse obstetric outcomes in patients with adenomyosis. Treatment seems to be associated with higher pregnancy rates and live births rates.

CONCLUSION

An association between adenomyosis and infertility seems to exist, and treatment could lead to improved fertility outcomes.

Metformin Alleviates Endometriosis and Potentiates Endometrial Receptivity via Decreasing VEGF and MMP9 and Increasing Leukemia Inhibitor Factor and HOXA10

Background: Endometriosis affects endometrial receptivity, a key factor for successful embryo implantation. Metformin treatment is associated with alleviating the symptoms of endometriosis; however the mechanism of metformin action is unclear. Neoangiogenesis plays an important role in the development and recurrence of endometriosis. In addition, the leukemia inhibitor factor (LIF) and HOXA10 genes are also distinguishing markers of endometriosis (decrease) and endometrial receptivity (increase). This study investigated the therapeutic potentials of metformin and the underlying mechanism using an in vivo rat endometriosis model.

Methods: Female Wistar albino mature rats with experimentally induced endometriosis were used in this study. Metformin was administered at doses of 100 mg/kg/d and 200 mg/kg/d. The volume of endometriotic implants was assessed. The protein and mRNA expression of the vascular endothelial growth factor (VEGF), matrix metalloproteinase-9 (MMP-9), the endometrial receptivity markers, LIF and HOXA10, were measured in the endometrium of rats with endometriosis.

Results: Metformin treatment significantly suppressed the growth of endometriotic implants. Further, the expression of VEGF and MMP-9 protein and mRNA in endometriotic implants were significantly reduced. Metformin also significantly upregulated LIF and HOXA10 expression in endometrium from rats with endometriosis. The inhibitory effect of metformin on the growth of endometriotic implants, VEGF and MMP-9, and upregulating effect on LIF and HOXA10, was optimal at a dose of 100 mg/kg/d.

Conclusion: Our in vivo data demonstrates that metformin treatment alleviates endometriosis and potentiates endometrial receptivity. The underlying mechanisms are associated with decreased expression of VEGF and MMP-9 genes and upregulation of the LIF and HOXA10 genes. The effect of metformin was optimal at 100 mg/kg/d. These findings provide a potential alternative for women with endometriosis with the potential to increase fertility. Metformin is an approved drug by FDA for diabetes and this study may add another potential clinical use for metformin.

Down-Regulation Ovulation-Induction Leads to Favorable Outcomes in a Single Frozen-Thawed Blastocyst Transfer RCT

Objective

Elective single embryo transfer (eSET) has been increasingly advocated to achieve the goal of delivering a single healthy baby. A novel endometrial preparation approach down-regulation ovulation-induction (DROI) proposed by our team was demonstrated in an RCT that DROI could significantly improve the reproductive outcome compared with modified natural cycle. We aimed to evaluate whether DROI improved clinic pregnancy rate in this single frozen-thawed blastocyst transfer RCT compared with hormone replace treatment (HRT).

Method

Eligible participants were recruited and randomized into one of two endometrial preparation regimens: DROI or HRT between March 15, 2019 and March 12, 2021. The primary outcome was clinical pregnancy rate (CPR). The secondary endpoints included ongoing pregnancy rate (OPR), biochemical miscarriage and first trimester pregnancy loss. This trial is registered at the Chinese Clinical Trial Registry, number ChiCTR2000039804.

Result s

A total of 330 women were randomized in a 1:1 ratio between two groups and 289 women received embryo transfer and completed the study (142 DROI; 147HRT). Pregnancy outcomes were significantly different between the two groups. The CPR and OPR in the DROI group were significantly higher than those of the HRT group (64.08% versus 46.94%, P<0.01; 56.34% versus 38.78%,P<0.01). The biochemical miscarriage and first trimester pregnancy loss were comparable between the two groups.

Conclusion s

The findings of this RCT support the suggestion that the DROI might be a more efficient and promising alternative endometrial preparation approach for FET. Moreover, DROI could play a critical role in promoting uptake of single embryo transfer strategies in FET.

Role of SIRT1 and Progesterone Resistance in Normal and Abnormal Endometrium

CONTEXT

Progesterone resistance, a known pathologic condition associated with a reduced cellular response to progesterone and heightened estrogen responses, appears to have a normal physiologic role in mammalian reproduction. The molecular mechanism responsible for progesterone resistance in normal and abnormal endometrium remains unclear.

OBJECTIVE

To examine the roles of sirtuin-1 (SIRT1) in normal endometrium as well as endometrium associated with infertility and endometriosis, as an epigenetic modulator associated with progesterone resistance.

METHODS

SIRT1 expression was examined by Western blot, quantitative real-time polymerase chain reaction, and immunohistochemistry in mouse uterus and human endometrium. Mice with uterine specific Sirt1 overexpression were developed to examine SIRT1's role in endometrial function and endometriosis development. EX-527, a SIRT1 inhibitor, and SRT1720, a SIRT1 agonist, were also used to evaluate SIRT1 effect on endometriosis.

RESULTS

In normal healthy women, endometrial SIRT1 is expressed only during menses. SIRT1 was dramatically overexpressed in the endometrium from women with endometriosis in both the epithelium and stroma. In mice, SIRT1 is expressed at the time of implantation between day 4.5 and 5.5 of pregnancy. Overexpression of SIRT1 in the mouse uterus leads to subfertility due to implantation failure, decidualization defects and progesterone resistance. SIRT1 overexpression in endometriotic lesions promotes worsening endometriosis development. EX-527 significantly reduced the number of endometriotic lesions in the mouse endometriosis model.

CONCLUSIONS

SIRT1 expression and progesterone resistance appears to play roles in normal endometrial functions. Aberrant SIRT1 expression contributes to progesterone resistance and may participate in the pathophysiology of endometriosis. SIRT1 is a novel and targetable protein for the diagnosis as well as treatment of endometriosis and the associated infertility seen in this disease.

Intrauterine interventions for women with two or more implantation failures: A systematic review and network meta-analysis

OBJECTIVE

To compare the effectiveness of different intrauterine interventions for women with two or more unexplained implantation failures.

DESIGN

A systematic review and network meta-analysis of randomized controlled trials (RCTs).

PATIENTS

Women with two or more implantation failures undergoing fresh or frozen embryo transfer (ET).

INTERVENTIONS

An electronic search of the following databases: Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL), and Embase.

MAIN OUTCOME MEASURES

Clinical pregnancy, live birth/ongoing pregnancy, and miscarriage.

RESULTS

We included 21 RCTs(3079 women) in the network meta-analysis. The network meta-analysis showed that compared with control treatment, platelet-rich plasma(PRP), peripheral blood mononuclear cells (PBMC), granulocyte colony-stimulating factor(G-CSF), human chorionic gonadotropin(HCG), and endometrial scratch(ES) significantly increased clinical pregnancy(OR 3.78, 95% CI 2.72 to 5.25; 2.79, 95% CI 1.75 to 4.45; 1.93, 95% CI 1.37 to 2.72; 1.80, 95% CI 1.18 to 2.72; 1.75, 95% CI 1.29 to 2.36, respectively). PRP ranked the highest in improving clinical pregnancy, followed by PBMC, G-CSF, HCG, and ES. Compared with control treatment, PRP, PBMC, and ES significantly increased live birth/ongoing pregnancy (OR 5.96, 95% CI 3.38 to 10.52; OR 2.55, 95% CI 1.27 to 5.11; OR 1.70, 95% CI 1.07 to 2.69, respectively). PRP ranked the highest in improving live birth/ongoing pregnancy, followed by PBMC, and ES.

CONCLUSIONS

PRP is the most effective intrauterine intervention in improving pregnancy outcome in women with two or more implantation failures.

Growth hormone in fertility and infertility: Mechanisms of action and clinical applications

Secreted by the anterior pituitary gland, growth hormone (GH) is a peptide that plays a critical role in regulating cell growth, development, and metabolism in multiple targeted tissues. Studies have shown that GH and its functional receptor are also expressed in the female reproductive system, including the ovaries and uterus. The experimental data suggest putative roles for GH and insulin-like growth factor 1 (IGF-1, induced by GH activity) signaling in the direct control of multiple reproductive functions, including activation of primordial follicles, folliculogenesis, ovarian steroidogenesis, oocyte maturation, and embryo implantation. In addition, GH enhances granulosa cell responsiveness to gonadotropin by upregulating the expression of gonadotropin receptors (follicle-stimulating hormone receptor and luteinizing hormone receptor), indicating crosstalk between this ovarian regulator and the endocrine signaling system. Notably, natural gene mutation of GH and the age-related decline in GH levels may have a detrimental effect on female reproductive function, leading to several reproductive pathologies, such as diminished ovarian reserve, poor ovarian response during assisted reproductive technology (ART), and implantation failure. Association studies using clinical samples showed that mature GH peptide is present in human follicular fluid, and the concentration of GH in this fluid is positively correlated with oocyte quality and the subsequent embryo morphology and cleavage rate. Furthermore, the results obtained from animal experiments and human samples indicate that supplementation with GH in the in vitro culture system increases steroid hormone production, prevents cell apoptosis, and enhances oocyte maturation and embryo quality. The uterine endometrium is another GH target site, as GH promotes endometrial receptivity and pregnancy by facilitating the implantation process, and the targeted depletion of GH receptors in mice results in fewer uterine implantation sites. Although still controversial, the administration of GH during ovarian stimulation alleviates age-related decreases in ART efficiency, including the number of oocytes retrieved, fertilization rate, embryo quality, implantation rate, pregnancy rate, and live birth rate, especially in patients with poor ovarian response and recurrent implantation failure.

Peri-implantation expression and regulation of ITGB8 in goat uterus

Ruminants have a superficial implantation pattern. The extended conceptus attaches to the receptive endometrium to form the cotyledonary placenta. During the attachment, a large number of events occur at the maternal-fetal interface. However, the related molecular mechanisms have not been fully understood. Integrin beta8 (ITGB8) is a subunit of integrin beta involved in embryo implantation. In this study, we determined peri-implantation expression and regulation of ITGB8 in goat uterus. The mRNA and protein levels of ITGB8 were both high in goat endometrial luminal epithelium (LE) and superficial glandular epithelium (sGE) during the adhesion period (Days 16-19 of pregnancy). Such expression profile was opposite to that of microRNA-187 (miR-187). Then, we validated that miR-187 targeted the 3' untranslated region (UTR) of ITGB8 in primary goat endometrial epithelial cells (EECs). In EECs, inhibition of miR-187 resulted in not only up-regulated ITGB8 level but also reduced cell proliferation and focal adhesion kinase (FAK) activity. Moreover, ITGB8 and miR-187 were regulated by interferon tau (IFNT). Altogether, in goat, the miR-187/ITGB8 axis may be involved in conceptus attachment and is downstream of IFNT. Our results will help us better understand the mechanisms of ruminant implantation and may provide a useful tool to improve the reproduction ratio for ruminants.

Decidualization Potency and Epigenetic Changes in Human Endometrial Origin Stem Cells During Propagation

Human endometrium derived mesenchymal stem cells (hEndSCs) offer a great promise for regenerative medicine and reproductive system disorders treatment methods based on cell therapy due to their broad differentiation potential and highly efficient proliferation. In our study, we investigated the characteristics of hEndSCs that were isolated from two sources: endometrium and menstrual blood, which both contain endometrial origin stem cells. Changes in gene and protein expression levels during long-term cultivation and decidualization potential were examined in endometrial stem cells (EndSCs) and menstrual blood stem cells (MenSCs). The decidualization process was induced on early and late passages of hEndSCs using dibutyryl cyclic-AMP (db-cAMP) and medroxyprogesterone acetate (MPA) agents. We demonstrated that after long-term cultivation of hEndSCs the expression of typical mesenchymal stromal cell surface markers such as CD44, CD73, CD90, CD105 and perivascular marker CD146 remains at a similar level throughout long-term cultivation. Additionally, hematopoietic and endothelial markers CD34, CD45 were also tested, they were negative in all cases. Analyzed stem cells gene markers, such as OCT4, SOX2, NANOG, KLF4, showed similar expression in all passages of hEndSCs. RT-qPCR results demonstrated that the expression of cell cycle control associated genes - CDK2, CCNA2, CCNE2, p21, p53 and Rb, among all groups was very similar. Expression of genes associated with senescence (ATM, JUND, TOP2A, MYC) was maintained at a similar level throughout passaging. In addition, Western blot analysis was used to assess changes in proteins’ levels associated to epigenetics (EZH2, SUZ12, H3K27me3) and cell cycle control (cyclinE1, p53) during long-term cultivation. The levels of proteins associated with epigenetic changes were fluctuated slightly depending on the patient. Also, we demonstrated that in all induced hEndSCs the expression of decidualization markers Prolactin (PRL), IGFBP1 and WNT4 was upregulated. In conclusion, we demonstrated successful decidualization of stem cells derived from two reproductive system resources: endometrium and menstrual blood by using db-cAMP and MPA regardless of the length of the stem cell passaging. According these findings, we suppose that endometrium derived stem cells and menstrual blood derived stem cells could have a potency not only for endometrium tissue regeneration, but could also become a successful therapy for reproductive system disorders, including infertility or recurrent pregnancy loss.

CircSTK40 contributes to recurrent implantation failure via modulating the HSP90/AKT/FOXO1 axis

Increasing evidence has revealed a close relationship between non-coding RNAs and recurrent implantation failure (RIF). However, the role of circular RNAs (circRNAs) in RIF pathogenesis remains largely unknown. Microarray analyses were used to identify the differentially expressed circRNA-circSTK40. Functional experiments, including decidualization induction and terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay, were performed to determine the effects of circSTK40 on human endometrial stromal cells (ESCs). The interactions between circSTK40 and proteins were investigated by RNA pull-down, RNA immunoprecipitation, and co-immunoprecipitation (coIP) assays. We observed that circSTK40 expression was upregulated in the RIF midluteal-phase endometrial samples. circSTK40 overexpression in ESCs inhibited the decidualization process but concurrently enhanced cell survival during stress. Mechanistically, circSTK40 directly bound to HSP90 and CLU, thus functioning as a scaffold to block their interactions and hinder the proteasomal degradation of HSP90. The resulting high levels of HSP90 led to the activation of the AKT pathway and downregulation of FOXO1 expression. Inhibitors of AKT (MK-2206) and HSP90 (17AAG) both abolished the effects of circSTK40 overexpression in ESCs and increased the decidualization levels in a dose-dependent manner. Our findings indicate a novel epigenetic mechanism for RIF pathogenesis involving circSTK40 activity and provide a foundation for targeted treatments in patients with low endometrial receptivity.

The effect of cytokine leukemia-inhibitory factor (LIF) and interleukin-11 (IL-11) gene expression on the primary infertility related to polycystic ovary syndrome, Tubal factor, and Unexplained infertility in Turkish women

Background

Successful implantation of blastocysts is indeed an important path in mammalian reproduction that is governed by a complicated web of cytokines interactions. Leukemia inhibitory factor (LIF) and interleukin-11 (IL-11) part of the interleukin (IL)-6 groups are cytokines that are needed for effective implantation and prevent infertility symptoms. This study aimed to determine the expression level (LIF, IL-11) genes in patients with primary infertility related to polycystic ovary syndrome (PCOS), tubal factor infertility (TFI), and unexplained infertility (UI).

Results

In this study, 75 infertility women and 40 controls were involved. The expressions of LIF and IL-11 genes were evaluated by quantitative real-time polymerase chain reaction qRT–PCR Light Cycler in patients and healthy controls. PCOS, TFI, and UI groups showed promising results regarding LIF gene, which appeared at very small levels compared to the control (p < 0.0001). Regarding IL-11, the two groups TFI and UI were significantly linked to the lower level of gene expression, while the PCOS group has no significant difference when it is compared to the control group (p < 0.0001, < 0.05, 0.19), respectively.

Conclusion

The current findings show that low levels of LIF and IL-11 gene expression are linked to various primary infertility conditions, including PCOS, tubal factor, and unexplained infertility since they play a fundamental role in embryo implantation.

Therapeutic potential of curcumin in endometrial disorders: Current status and future perspectives

Endometrial disorders collectively encompass a broad spectrum of pathologies, including but not limited to endometriosis, endometrial cancer and endometritis. The current therapeutic management of these diseases is associated with several limitations. This has prompted interest in the use of plant-based bioactive compounds as alternative strategies to achieve high therapeutic efficacy and avoid adverse effects. In this context, curcumin, a polyphenol abundantly present in turmeric, is gaining increasing attention for its therapeutic potential to restore homeostasis in endometrial dysfunctionality. We comprehensively review the multifaceted role of curcumin, discussing mechanistic insights in various endometrial pathologies. We also provide an in-depth analysis of the concerns and challenges associated with the role of curcumin in endometrial research and outline a road map for future investigations.

NLRP3 promotes endometrial receptivity by inducing epithelial-mesenchymal transition of the endometrial epithelium

Endometrial receptivity is crucial for successful embryo implantation. It is regulated by multiple factors which include ovarian steroid hormones and the immune microenvironment among others. Nod-Like Receptor Pyrins-3 (NLRP3) is a key intracellular pattern-recognition receptor and a critical component of the inflammasome, which plays an essential role in the development of inflammation and of immune responses. However, the physiological functions of NLRP3 in the endometrium remain largely unclear. This study investigated the physiological and pathological significance of NLRP3 in human endometrial epithelial cell during the implantation window. NLRP3 is highly expressed during the mid-proliferative and mid-secretory phases of the human endometrium and transcriptionally up-regulated by estradiol (E2) through estrogen receptor β (ERβ). In addition, NLRP3 promotes embryo implantation and enhances epithelial-mesenchymal transition (EMT) of Ishikawa (IK) cells via both inflammasome-dependent and inflammasome-independent pathways, which might provide a novel insight into endometrial receptivity and embryo implantation. Our findings suggest that NLRP3, which is transcriptionally regulated by E2, induces epithelial-mesenchymal transition of endometrial epithelial cells and promotes embryo adhesion.

Mucus-producing 3D cell culture models

In vitro cell-based models have been used for a long time since they are normally easily obtained and have an advantageous cost-benefit. Besides, they can serve a variety of ends, from studying drug absorption and metabolism to disease modeling. However, some in vitro models are too simplistic, not accurately representing the living tissues. It has been shown, mainly in the last years, that fully mimicking a tissue composition and architecture can be paramount for cellular behavior and, consequently, for the outcomes of the studies using such models. Because of this, 3D in vitro cell models have been gaining much attention, since they are able to better replicate the in vivo environment. In this review we focus on 3D models that contain mucus-producing cells, as mucus can play a pivotal role in drug absorption. Being frequently overlooked, this viscous fluid can have an impact on drug delivery. Thus, the aim of this review is to understand to which extent can mucus affect mucosal drug delivery and to provide a state-of-the-art report on the existing 3D cell-based mucus models.

A 3D endometrial organotypic model simulating the acute inflammatory decidualisation initiation phase with epithelial induction of the key endometrial receptivity marker, integrin αVβ3

STUDY QUESTION

Is it possible to develop a simplified physiological in vitro system representing the key cell-types associated with a receptive endometrial phenotype?

SUMMARY ANSWER

We present a new concept to investigate endometrial receptivity, with a 3D organotypic co-culture model to simulate an early and transient acute autoinflammatory decidual status that resolves in the induction of a receptive endometrial phenotype.

WHAT IS KNOWN ALREADY

Embryo implantation is dependent on a receptive uterine environment. Ovarian steroids drive post-ovulation structural and functional changes in the endometrium, which becomes transiently receptive for an implanting conceptus, termed the ‘window of implantation’, and dysregulation of endometrial receptivity is implicated in a range of reproductive, obstetric, and gynaecological disorders and malignancies. The interactions that take place within the uterine microenvironment during this time are not fully understood, and human studies are constrained by a lack of access to uterine tissue from specific time-points during the menstrual cycle. Physiologically relevant in vitro model systems are therefore fundamental for conducting investigations to better understand the cellular and molecular mechanisms controlling endometrial receptivity.

STUDY DESIGN, SIZE, DURATION

We conducted an in vitro cell culture study using human cell lines and primary human cells isolated from endometrial biopsy tissue. The biopsy tissue samples were obtained from three women attending gynaecological outpatient departments in NHS Lothian. The work was carried out between December 2016 and April 2019, at the MRC Centre for Reproductive Health, Queen’s Medical Research Institute, University of Edinburgh.

PARTICIPANTS/MATERIALS, SETTING, METHODS

An endometrial stromal cell (ESC) line, and endometrial epithelial cells (EECs) isolated from endometrial biopsy tissue and expanded in vitro by conditional reprogramming, were used throughout the study. Immunocytochemical and flow cytometric analyses were used to confirm epithelial phenotype following conditional reprogramming of EECs. To construct an endometrial organotypic co-culture model, ESCs were embedded within a 3D growth factor-reduced Matrigel structure, with a single layer of conditionally reprogrammed EECs seeded on top. Cells were stimulated with increasing doses of medroxyprogesterone acetate, cAMP and oestradiol, in order to induce ESC decidual transformation and endometrial receptivity. Decidual response and the induction of a receptive epithelial phenotype were assessed by immunocytochemical detection and quantitative in-cell western analyses, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

A transient up-regulation of the interleukin-33 receptor protein, ST2L, was observed in ESCs, indicating a transient autoinflammatory decidual response to the hormonal stimulation, known to induce receptivity gene expression in the overlying epithelium. Hormonal stimulation increased the EEC protein levels of the key marker of endometrial receptivity, integrin αVβ3 (n = 8; *P < 0.05; ***P < 0.0001). To our knowledge, this is the first demonstration of a dedicated endometrial organotypic model, which has been developed to investigate endometrial receptivity, via the recapitulation of an early decidual transitory acute autoinflammatory phase and induction of an epithelial phenotypic change, to represent a receptive endometrial status.

LIMITATIONS, REASONS FOR CAUTION

This simplified in vitro ESC-EEC co-culture system may be only partly representative of more complex in vivo conditions.

WIDER IMPLICATIONS OF THE FINDINGS

The 3D endometrial organotypic model presented here may offer a valuable tool for investigating a range of reproductive, obstetric, and gynaecological disorders, to improve outcomes for assisted reproductive technologies, and for the development of advances in contraceptive methods.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported in part by a Medical Research Council Centre Grant (project reference MR/N022556/1). R.F. was the recipient of a Moray Endowment award and a Barbour Watson Trust award. C.-J.L. is a Royal Society of Edinburgh Personal Research Fellow, funded by the Scottish Government. The authors have no conflicts of interest to declare.

LncRNA LINC01088 inhibits the function of trophoblast cells, activates the MAPK-signaling pathway and associates with recurrent pregnancy loss

Long noncoding RNAs (lncRNAs) have been reported to be involved in various cellular processes and to participate in a variety of human diseases. Recently, increasing studies have reported that lncRNAs are related to many reproductive diseases, such as pathogenesis of recurrent pregnancy loss (RPL), preeclampsia (PE) and gestational diabetes mellitus (GDM). In this study, we aimed to investigate the effect of LINC01088 in trophoblast cells and its potential role in pathogenesis of RPL. LINC01088 was found to be upregulated in first-trimester chorionic villi tissues from RPL patients. Increased LINC01088 repressed proliferation, migration and invasion of trophoblast cells, and promoted apoptosis of trophoblast cells. Further exploration indicated that LINC01088 decreased the production of nitric oxide (NO) by binding and increasing Arginase-1 and decreasing eNOS protein levels. Importantly, JNK and p38 MAPK-signaling pathways were active after overexpression of LINC01088. In conclusion, our studies demonstrated that LINC01088 plays an important role in the pathogenesis of RPL, and is a potential therapeutic target for the treatment of RPL.

Unresponsive thin endometrium caused by Asherman syndrome treated with umbilical cord mesenchymal stem cells on collagen scaffolds: a pilot study

Background

Unresponsive thin endometrium caused by Asherman syndrome (AS) is the major cause of uterine infertility. However, current therapies are ineffective. This study is to evaluate the effect of transplantation with collagen scaffold/umbilical cord mesenchymal stem cells (CS/UC-MSCs) on this refractory disease.

Methods

Eighteen infertile women with unresponsive thin endometrium, whose frozen–thawed embryo transfers (FETs) were cancelled due to reduced endometrial thickness (ET ≤ 5.5 mm), were enrolled in this before and after self-control prospective study. Hysteroscopic examination was performed to confirm no intrauterine adhesions, then twenty million UC-MSCs loaded onto a CS were transplanted into the uterine cavity in two consecutive menstrual cycles. Then uterine cavity was assessed through hysteroscopy after two transplants. FETs were performed in the following cycle. Pregnancy outcomes were followed up. Endometrial thickness, uterine receptivity and endometrial angiogenesis, proliferation and hormone response were compared before and after treatment.

Results

Sixteen patients completed the study. No treatment-related serious adverse events occurred. Three months after transplantation, the average ET increased from 4.08 ± 0.26 mm to 5.87 ± 0.77 mm (P < 0.001). Three of 15 patients after FET got pregnant, of whom 2 gave birth successfully and 1 had a miscarriage at 25 weeks’ gestation. One of 2 patients without FET had a natural pregnancy and gave birth normally after transplantation. Immunohistochemical analysis showed increased micro-vessel density, upregulated expression of Ki67, estrogen receptor alpha, and progesterone receptor, indicating an improvement in endometrial angiogenesis, proliferation, and response to hormones.

Conclusion

CS/UC-MSCs is a promising and potential approach for treating women with unresponsive thin endometrium caused by AS.

Trial registration

ClinicalTrials.gov NCT03724617. Registered on 26 October 2018—prospectively registered, https://register.clinicaltrials.gov/

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02499-z.

Fragile X-Related Protein 1 (FXR1) Promotes Trophoblast Migration at Early Pregnancy via Downregulation of GDF-15 Expression

Fragile X-related protein 1 (FXR1) is an RNA-binding protein that can regulate specific mRNA decay in cells. Our previous study showed that FXR1 expression was significantly decreased in trophoblasts from patients with unexplained recurrent spontaneous abortion (RSA); however, the role of FXR1 in trophoblast function during early placenta development has not been fully elucidated. In this study, we found that knockdown of FXR1 using siRNA effectively inhibited the migration of HTR-8 cells and extravillous trophoblast (EVT) outgrowth in an ex vivo extravillous explant culture model. Furthermore, through analysis of a panel of cytokines, we found that the GDF-15 protein was upregulated after knockdown of FXR1 in HTR-8/SVneo cells. This was further confirmed by western blotting and immunofluorescence in HTR-8/SVneo cells and an extravillous explant. Our data also showed that FXR1 expression was downregulated and GDF-15 was upregulated in chorionic villous tissues from RSA patients compared with those from healthy controls (HCs). Further, immunohistochemistry showed a strong expression of GDF-15 in chorionic villous tissue in the RSA group, which was mainly distributed in villous trophoblasts (CTBs) and syncytiotrophoblasts (STBs). Moreover, knockdown of GDF-15 enhanced the migration of HTR-8 cells, while overexpression of GDF-15 using plasmid or treatment with recombinant human GDF-15 protein inhibited trophoblast migration. Importantly, RNA-binding protein immunoprecipitation showed that FXR1 directly bound to the 3'-UTR of GDF-15 mRNA to promote GDF-15 mRNA decay. Together, our data provide new insight into the function of FXR1 in human placenta via regulation of GDF-15 expression in trophoblasts and suggest a possible pathological process involved in RSA.