Management of thin endometrium in assisted reproduction: a clinical practice guideline from the Canadian Fertility and Andrology Society

Metformin ameliorates endometrial thickness in a rat model of thin endometrium

Metformin, a well-established anti-diabetic drug, is also used in managing various other metabolic disorders including polycystic ovarian syndrome (PCOS). There are evidences to show that metformin improves endometrial functions in PCOS women. However, fewer studies have explored the direct effects of metformin on endometrium. Previous in vitro studies have shown that therapeutic serum concentrations of metformin enhance endometrial epithelial cell proliferation. The present study was undertaken to investigate in vivo effects of metformin on endometrial proliferation in a rat model of thin endometrium. Toward this, a rat model of thin endometrium was developed. Metformin (0.1% or 1% w/v) was administrated orally for 15 days in rats with thin endometrium. Oral metformin administration for three consecutive estrous cycles (15 days) in the thin endometrium rat model led to an increase in endometrial thickness compared to sham endometrium. Histological analysis showed a significant increase in the number of endometrial glands (P < 0.05), stromal cells (P < 0.01) and blood vessels (P < 0.01) in metformin-treated (n = 10 in each group) uterine horns compared to sham (saline-treated) uterine horns in rats. The expression of proliferating cell nuclear antigen and vascular epithelial growth factor was found to be upregulated on treatment with 1% metformin-treated group (n = 7). However, pregnancy outcomes in the rats treated with metformin remained unaltered despite the restoration of endometrial thickness. In conclusion, the study demonstrated that metformin ameliorates endometrial thickness in a rat model of thin endometrium by increasing endometrial proliferation and angiogenesis, without restoration of embryo implantation.

Exosomes Derived from Mesenchymal Stem Cells Increase the Viability of Damaged Endometrial Cells via the miR-99b-5p/PCSK9 Axis

The aim of this article was to investigate whether exosomes derived from bone marrow mesenchymal stem cells repair damaged endometrial stromal cells (EnSCs) through the miR-99b-5p/PCSK9 axis. Exosomes derived from bone marrow mesenchymal stem cells (BMSC-exos) were isolated by ultracentrifugation and characterized using transmission electron microscopy and nanoflow cytometry. A mifepristone-induced EnSC injury model was established in vitro, and the uptake of BMSC-exos was assessed. EnSCs were divided into three groups: the normal group (ctrl), EnSC injury group (model), and BMSC-exo treatment group. The effects of BMSC-exos on EnSC proliferation, apoptosis, and vascular endothelial growth factor (VEGF) expression were assessed by coculturing MSC-exos with endometrial cells. Furthermore, high-throughput sequencing was used to identify differentially expressed genes (DEGs). Through bioinformatics analysis, reverse transcription-quantitative polymerase chain reaction, western blotting, the CCK8 assay, immunohistochemistry, and dual-luciferase experiments, the potential mechanism by which BMSC-exos-derived miRNAs repair EnSC injury was studied. BMSC-exos expressed the marker proteins CD9 and CD63. Laser confocal microscopy showed that BMSC-exos could enter damaged EnSCs. In the BMSC-exos-EnSC coculture group compared with the model group, BMSC-exos significantly increased the proliferation of damaged EnSCs and inhibited cell apoptosis in a dose-dependent manner. The expression levels of Caspase-3, Caspase-9, Bax, and VEGF mRNA were significantly downregulated in the BMSC-exos-EnSC coculture group, whereas Bcl-2 expression was upregulated. We identified 28 overlapping DEGs between the model and ctrl groups and between the BMSC-exo and model groups. Transfection with miR-99b-5p mimics significantly decreased PCSK9 gene expression and inhibited the expression of the autophagy-related proteins Beclin-1 and LC3-II/I and apoptosis, thereby promoting EnSC proliferation. Transfection with a miR-99b-5p inhibitor showed the opposite effects. Beclin-1, LC3-II/I, and PCSK9 expression in the thin endometrium was significantly increased. miR-99b-5p promoted cell proliferation by targeting PCSK9. BMSC-exos promoted endometrial proliferation, and miR-99b-5p inhibited cell apoptosis and promoted EnSC proliferation by targeting PCSK9, providing a new target for the treatment of thin endometrium.

Autologous PRP therapy for thin endometrium: A self-controlled case series study across menstrual cycles

OBJECTIVES

Thin endometrium (TE) compromises endometrial receptivity, often leading to implantation failure and lower clinical pregnancy rates. As autologous platelet-rich plasma (PRP) emerges as a potential remedy, the present study focused on its therapeutic effects on TE in infertile women who underwent frozen embryo transfer.

STUDY DESIGN

Patients with TE who underwent frozen embryo transfer treatment in our hospital were included. To diminish individual variability, a self-controlled series approach was used. Two menstrual study cycles were arranged for each participant before the actual embryo transfer cycle; PRP treatment was conducted in the second cycle. Key metrics analyzed included endometrial thickness and the expression of specific endometrial biomarkers including HOXA-10, Ki67, and αvβ3 integrin. Transvaginal ultrasound was employed to measure endometrial thickness on Days 11 and 14, and an endometrial biopsy was conducted on progesterone Day 5 of the first two cycles. Pregnancy outcomes were observed after the embryo transfer cycle.

RESULTS

PRP treatment significantly increased the median endometrial thickness, from 5.8 mm to 6.5 mm (P = 0.0066). Additionally, PRP treatment resulted in a statistically significant increase in the H-score for all endometrial markers. Importantly, during the subsequent embryo transfer cycle with PRP treatment, two patients successfully achieved pregnancies, both culminating in live births.

CONCLUSIONS

These findings emphasize the potential of PRP in improving endometrial conditions, especially for individuals grappling with thin endometrium issues, as underscored by this self-comparison methodology.

Evolution of biotechnological advances and regenerative therapies for endometrial disorders: a systematic review

BACKGROUND

The establishment and maintenance of pregnancy depend on endometrial competence. Asherman syndrome (AS) and intrauterine adhesions (IUA), or endometrial atrophy (EA) and thin endometrium (TE), can either originate autonomously or arise as a result from conditions (i.e. endometritis or congenital hypoplasia), or medical interventions (e.g. surgeries, hormonal therapies, uterine curettage or radiotherapy). Affected patients may present an altered or inadequate endometrial lining that hinders embryo implantation and increases the risk of poor pregnancy outcomes and miscarriage. In humans, AS/IUA and EA/TE are mainly treated with surgeries or pharmacotherapy, however the reported efficacy of these therapeutic approaches remains unclear. Thus, novel regenerative techniques utilizing stem cells, growth factors, or tissue engineering have emerged to improve reproductive outcomes.

OBJECTIVE AND RATIONALE

This review comprehensively summarizes the methodologies and outcomes of emerging biotechnologies (cellular, acellular, and bioengineering approaches) to treat human endometrial pathologies. Regenerative therapies derived from human tissues or blood which were studied in preclinical models (in vitro and in vivo) and clinical trials are discussed.

SEARCH METHODS

A systematic search of full-text articles available in PubMed and Embase was conducted to identify original peer-reviewed studies published in English between January 2000 and September 2023. The search terms included: human, uterus, endometrium, Asherman syndrome, intrauterine adhesions, endometrial atrophy, thin endometrium, endometritis, congenital hypoplasia, curettage, radiotherapy, regenerative therapy, bioengineering, stem cells, vesicles, platelet-rich plasma, biomaterials, microfluidic, bioprinting, organoids, hydrogel, scaffold, sheet, miRNA, sildenafil, nitroglycerine, aspirin, growth hormone, progesterone, and estrogen. Preclinical and clinical studies on cellular, acellular, and bioengineering strategies to repair or regenerate the human endometrium were included. Additional studies were identified through manual searches.

OUTCOMES

From a total of 4366 records identified, 164 studies (3.8%) were included for systematic review. Due to heterogeneity in the study design and measured outcome parameters in both preclinical and clinical studies, the findings were evaluated qualitatively and quantitatively without meta-analysis. Groups using stem cell-based treatments for endometrial pathologies commonly employed mesenchymal stem cells (MSCs) derived from the human bone marrow or umbilical cord. Alternatively, acellular therapies based on platelet-rich plasma (PRP) or extracellular vesicles are gaining popularity. These are accompanied by the emergence of bioengineering strategies based on extracellular matrix (ECM)-derived hydrogels or synthetic biosimilars that sustain local delivery of cells and growth factors, reporting promising results. Combined therapies that target multiple aspects of tissue repair and regeneration remain in preclinical testing but have shown translational value. This review highlights the myriad of therapeutic material sources, administration methods, and carriers that have been tested.

WIDER IMPLICATIONS

Therapies that promote endometrial proliferation, vascular development, and tissue repair may help restore endometrial function and, ultimately, fertility. Based on the existing evidence, cost, accessibility, and availability of the therapies, we propose the development of triple-hit regenerative strategies, potentially combining high-yield MSCs (e.g. from bone marrow or umbilical cord) with acellular treatments (PRP), possibly integrated in ECM hydrogels. Advances in biotechnologies together with insights from preclinical models will pave the way for developing personalized treatment regimens for patients with infertility-causing endometrial disorders such as AS/IUA, EA/TE, and endometritis.

REGISTRATION NUMBER

https://osf.io/th8yf/.

Validity of stem cell-loaded scaffolds to facilitate endometrial regeneration and restore fertility: a systematic review and meta-analysis

Objective

Various stem cell-loaded scaffolds have demonstrated promising endometrial regeneration and fertility restoration. This study aimed to evaluate the efficacy of stem cell-loaded scaffolds in treating uterine injury in animal models.

Methods

The PubMed, Embase, Scopus, and Web of Science databases were systematically searched. Data were extracted and analyzed using Review Manager version 5.4. Improvements in endometrial thickness, endometrial glands, fibrotic area, and number of gestational sacs/implanted embryos were compared after transplantation in the stem cell-loaded scaffolds and scaffold-only group. The standardized mean difference (SMD) and confidence interval (CI) were calculated using forest plots.

Results

Thirteen studies qualified for meta-analysis. Overall, compared to the scaffold groups, stem cell-loaded scaffolds significantly increased endometrial thickness (SMD = 1.99, 95% CI: 1.54 to 2.44, P < 0.00001; I² = 16%) and the number of endometrial glands (SMD = 1.93, 95% CI: 1.45 to 2.41, P < 0.00001; I² = 0). Moreover, stem cell-loaded scaffolds present a prominent effect on improving fibrosis area (SMD = -2.50, 95% CI: -3.07 to -1.93, P < 0.00001; I² = 36%) and fertility (SMD = 3.34, 95% CI: 1.58 to 5.09, P = 0.0002; I² = 83%). Significant heterogeneity among studies was observed, and further subgroup and sensitivity analyses identified the source of heterogeneity. Moreover, stem cell-loaded scaffolds exhibited lower inflammation levels and higher angiogenesis, and cell proliferation after transplantation.

Conclusion

The evidence indicates that stem cell-loaded scaffolds were more effective in promoting endometrial repair and restoring fertility than the scaffold-only groups. The limitations of the small sample sizes should be considered when interpreting the results. Thus, larger animal studies and clinical trials are needed for further investigation.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO, identifier CRD42024493132.

Intrauterine Infusion and Hysteroscopic Injection of Autologous Platelet-Rich Plasma for Patients with a Persistent Thin Endometrium: A Prospective Case-Control Study

Objectives: To evaluate the effect of intrauterine infusion and hysteroscopic injection of autologous platelet-rich plasma (PRP) in patients with a persistent thin endometrium (EM) undergoing euploid frozen embryo transfer (EFET) cycles. Methods: This prospective case-control study enrolled 116 infertile women with thin EM (<7 mm) who underwent hormone replacement therapy (HRT) for EFET. These women had experienced at least one previous unsuccessful EFET cycle, which either resulted in the cancellation of the cycle or failure of pregnancy. A total of 55 women received an intrauterine infusion of PRP before FET, 38 received a hysteroscopic injection of PRP, and 23 received standard HRT treatment without PRP (control group). Only euploid embryos were transferred in these cycles. The primary outcomes were the implantation rate (IR) and clinical pregnancy rate (CPR) after EFET. Results: After receiving intrauterine infusion and hysteroscopic injection of PRP, 78.2% and 55.3% of patients, respectively, showed an EM thickness exceeding 7 mm, followed by embryo transfer. The hysteroscopic injection group demonstrated significantly higher IR (52%), a higher trend of CPR (52%), and a higher live birth rate (38%) than the control group (18%, 22%, and 4%). Conclusions: Intrauterine infusion and hysteroscopic injection of autologous PRP may be effective methods to increase EM thickness in HRT cycles. According to our results, both methods could increase EM thickness, while hysteroscopic injection appeared to provide more significant assistance in increasing IR, CPR, and live birth rate after EFET in patients with persistent thin EM.

New advances in the treatment of thin endometrium

Thin endometrium (TE) is defined as a mid-luteal endometrial thickness ≤7mm. TE can affect endometrial tolerance, leading to lower embryo implantation rates and clinical pregnancy rates, and is also associated with impaired outcomes from assisted reproductive treatment. Herein, we systematically review TE causes, mechanisms, and treatments. TE pathogenesis has multiple causes, with the endometrium becoming thinner with age under hormonal influence. In addition, uterine cavity factors are important, as the inflammatory environment may affect expressions of certain genes thereby inhibiting endometrial stromal cell proliferation and promoting apoptosis. Long-term oral contraceptive use or the use of ovulation-promoting drugs are also definite factors contributing to endometrial thinning. Other patients have primary factors, for which the clinical etiology remains unknown. The main therapeutic strategies available for TE are pharmacological (including hormonal and vasoactive drugs), regenerative medicine, intrauterine infusion of growth factor-granulocyte colony-stimulating factor, autologous platelet-rich plasma, and complementary alternative therapies (including traditional Chinese herbal medicine and acupuncture). However, the associated mechanisms of action are currently unclear. Clinical scholars have proposed various approaches to improve treatment outcomes in patients with TE, and are exploring the principles of efficacy, offering potentials for novel treatments. It is hoped that this will improve TE tolerance, increase embryo implantation rates, and help more couples with infertility with effective treatments.

The impact of estradiol supplementation on endometrial thickness and intrauterine insemination outcomes

The impact of estrogen supplementation during the follicular/proliferative phase on the endometrial lining thickness (EMT) prior to intrauterine insemination (IUI) remains largely unstudied. Our study examined changes in EMT and rates of clinical pregnancy, miscarriage, and live birth for all patients who completed an IUI cycle at Stanford Fertility Center from 2017-2023 (n = 2281 cycles). Cycles with estradiol supplementation (n = 309) were compared to reference cycles without supplementation (n = 1972), with the reference cohort further categorized into cycles with a pre-ovulatory EMT of < 7 mm ("thin-lining", n = 536) and ≥ 7 mm ("normal-lining", n = 1436). The estradiol group had a statistically significant greater change in EMT from baseline to ovulation compared to the thin-lining reference groups (2.4 mm vs 1.9 mm, p < =0.0001). Similar rates of clinical pregnancy and live birth were observed. After adjusting for age, BMI, race/ethnicity, infertility diagnosis, and EMT at trigger, the estradiol cohort had a significantly increased odds of miscarriage versus the entire reference cohort (2.46, 95 % confidence interval [1.18, 5.14], p = 0.02). Thus, although estradiol supplementation had a statistically significant increase in EMT compared to IUI cycles with thin pre-ovulatory EMT (<7 mm), this change did not translate into improved IUI outcomes such as increased rates of clinical pregnancy and live birth or decreased rate of miscarriage. Our study suggests that supplemental estradiol does not appear to improve IUI outcomes.

Effects of the Zishen Yutai Pill compared with placebo on pregnancy outcomes among women in a fresh embryo transfer cycle: a Post Hoc subgroup analysis of a randomized controlled trial

Objective

To assess whether the administration of Zishen Yutai Pill (ZYP) could improve the pregnancy outcomes in different subgroups of women undergoing fresh embryo transfer cycles.

Materials and methods

This is a post hoc analysis of a large scale, placebo-controlled, double blind, randomized clinical trial (RCT) regarding the use of ZYP during assisted reproductive technology (ART) treatment. The RCT was conducted at 19 in vitro fertilization (IVF) centers between April 2014 and June 2017. A total of 2265 women undergoing fresh embryo transfer cycles were randomly assigned in a 1:1 ratio to receive ZYP (n = 1131) or placebo (n = 1134). Post hoc logistic regression analyses were applied in this study to examine the between-group differences of ZYP and placebo on clinical pregnancy rate among different subgroups. Detailed analyses, both in intention-to-treat (ITT) and per-protocol population, were also conducted in specific subgroups with regards to rates of implantation, biochemical pregnancy, clinical pregnancy, live birth, pregnancy loss, as well as other neonatal indices.

Results

ZYP showed a significantly higher clinical pregnancy rates than placebo in the ITT population. Detailed subgroup analyses were conducted in subgroup in advanced maternal age (AMA, ≥ 35 years old) and overweight/obese patients (BMI > 24), due to the clinical importance and statistical results. In these subgroups, baseline characteristics were similar between two arms (all P > 0.05). Significantly elevated clinical pregnancy rates were observed in ZYP cohort (both P < 0.05) compared with the placebo group. Results also showed that ZYP treatment resulted in significantly higher rates of implantation, biochemical pregnancy in AMA or overweight/obese patients in ITT analysis (all P < 0.05).

Conclusions

The current post hoc subgroup analysis suggested that AMA and overweight/obese women could experience clinical benefits when treated with ZYP in their fresh embryo transfer cycles. The study provides references for the use of ZYP in ART practices. However, further studies in specific subgroups should be examined in more rigorous clinical trial settings.

Clinical trial registration

Chictr.org.cn, ChictrTRC-14004494.

Involvement of small leucine-rich proteoglycans and telocytes in thin and thick human endometrium: immunohistochemical and ultrastructural examination

Thin endometrium, defined as an endometrial thickness of less than 7 mm during the late follicular phase, is a common cause of frequent cancelation of embryo transfers or recurrent implantation failure during assisted reproductive treatment. Small proteoglycans regulate intracellular signaling cascades by bridging other matrix molecules and tissue elements, affecting cell proliferation, adhesion, migration, and cytokine concentration. The aim of the study is to investigate the role of small leucine-rich proteoglycans in the pathogenesis of thin and thick human endometrium and their differences from normal endometrium in terms of fine structure properties. Normal, thin, and thick endometrial samples were collected, and small leucine-rich proteoglycans (SLRPs), decorin, lumican, biglycan, and fibromodulin immunoreactivities were comparatively analyzed immunohistochemically. The data were compared statistically. Moreover, ultrastructural differences among the groups were evaluated by transmission electron microscopy. The immunoreactivities of decorin, lumican, and biglycan were higher in the thin endometrial glandular epithelium and stroma compared to the normal and thick endometrium (p < .001). Fibromodulin immunoreactivity was also higher in the thin endometrial glandular epithelium than in the normal and thick endometrium (p < .001). However, there was no statistical difference in the stroma among the groups. Ultrastructural features were not profoundly different among cases. Telocytes, however, were not seen in the thin endometrium in contrast to normal and thin endometrial tissues. These findings suggest a possible role of changes in proteoglycan levels in the pathogenesis of thin endometrium.

Letrozole During Frozen Embryo Transfer in Women With Polycystic Ovarian Syndrome: A Randomized Controlled Trial

OBJECTIVE

To compare live-birth rates between letrozole application and artificial cycle for endometrium preparation during frozen embryo transfer (FET) cycle among women with polycystic ovarian syndrome (PCOS).

METHODS

A randomized controlled trial was conducted. Women with PCOS were randomized to letrozole application for ovulation induction compared with artificial cycle for endometrial preparation during FET. The primary outcome was live-birth rate per embryo transfer. Secondary outcomes included pregnancy-related outcomes, perinatal outcomes, and maternal complication rates. Assuming α=0.05 and 80% power, 186 patients per group were required to demonstrate a difference of 15% in live-birth rate: 205 patients (at least) per group were randomized to allow for a 10% dropout rate.

RESULTS

Four hundred twenty patients were enrolled from 2018 to 2021. Two hundred ten patients were assigned to the letrozole application group, and 210 were assigned to the artificial cycle group. There was no difference in the live-birth rate (42.4% vs 42.9%, P =>.99). There was no difference in secondary outcomes, including clinical pregnancy rate (51.4% vs 56.2%, P =.378), implantation rate (51.8% vs 55.8%, P =.401), and miscarriage rate (8.6% vs 11.0%, P =.511). For perinatal outcomes, singleton birth weight was significantly higher in the artificial cycle group (3,108±56 g vs 3,301±58, P =.018), and the incidence of gestational diabetes mellitus (GDM) was significantly higher in letrozole application group (14.6% vs 5.6%, P =.050). The other outcome was no difference in maternal complications.

CONCLUSION

There was no difference in pregnancy outcomes between letrozole application compared with artificial cycle for endometrial preparation in women with PCOS who underwent FET. The risk of GDM was higher in the letrozole application group, and the singleton birth weight was lower in the artificial cycle group.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR1800014746.

Effect of tamoxifen in patients with thin endometrium who underwent frozen-thawed embryo transfer cycles: a retrospective study

Introduction

Thin endometrium leads to an impaired implantation rate. The aim of the study is to compare the clinical outcomes of tamoxifen (TAM) and hormone replacement therapy (HRT) used in patients with thin endometrium (<7mm) in frozen-thawed embryo transfer (FET)cycles.

Methods

A total of 176 FET cycles with thin endometrium were retrospectively analyzed in our center from Jan 2020 to May 2022. According to patients' own will, 112 patients were allocated to the HRT group and 64 patients chose the TAM protocol. Clinical outcomes were compared between two groups.

Result

The duration of treatment was shorter in the TAM group(12.03±2.34d) than the HRT group (16.07±2.52 d), which was statistically different (p<0.05). The endometrial thickness on the transfer day of the TAM group (7.32±1.28 mm) was significantly thicker than that of the HRT group (6.85±0.89mm, p<0.05). The clinical pregnancy rate of the TAM group (50.0%) was higher than that of the HRT group (36.6%), but there was no significant difference (p >0.05). The early miscarriage rate was significantly lower in the TAM group compared with the HRT group (5.9% Vs 26.8%, adjusted OR 0.10, p<0.05), while the live birth rate was higher in the TAM group (46.9% Vs 26.8%, adjusted OR 2.24, p<0.05) compared with the HRT group.

Conclusion

For patients with thin endometrium, TAM effectively improved the endometrial thickness and increased the live birth rate. TAM can be used as an alternative protocol for patients with thin endometrium.

Autologous Platelet-Rich Plasma (PRP) Efficacy on Endometrial Thickness and Infertility: A Single-Centre Experience from Romania

(1) Background: During IVF (in vitro fertilization), a proper endometrium thickness is one of the most difficult parameters to achieve and one of the most important prognostic factors of the success rate. One major problem is the high cancelation percentage in frozen embryo transfer cycles. The focus on the adjuvant methods for improving endometrium thickness is an on-going subject of interest. (2) Methods: This prospective single-arm self-control study was conducted in an IVF centre in Oradea, Romania. The patients were divided into two groups. The control group included 51 patients with at least one attempt to transfer a good-quality blastocyst, but the endometrial thickness did not surpass 7 mm under standard endometrial preparation protocol with oestradiol and with adjuvant therapy (other than PRP, such as aspirin, vitamin C, and vitamin E), and the study group included the same 51 patients that had the embryo transfer performed under the same standard endometrial preparation protocol with oestradiol preparation protocol and intrauterine PRP infusion. (3) Results: In our study, the PRP treatment had a positive impact on the parameters that were followed for the evaluation of the success rate of the embryo transfer procedure. The endometrial thickness (an increase in endometrial thickness by 0.6 mm after PRP treatment with p = 0.0001) and the clinical pregnancy rate (having a MD ± SD of 0 ± 0.38 before PRP treatment and with an increase to 0.5 ± 0.1 after the PRP treatment, p = 0.0004) were statistically significant (4) Conclusions: PRP has a positive effect in promoting endometrial proliferation, improving embryo implantation rate and clinical pregnancy rate for women with thin endometrium.

Network Pharmacology Analysis of the Mechanisms Underlying the Therapeutic Effects of Yangjing Zhongyu Tang on Thin Endometrium

Purpose

Yangjing Zhongyu Tang (YJZYT) is a classic Chinese prescription for infertility treatment and exerts therapeutic effects via activity on the thin endometrium (TE). However, the major components and underlying mechanisms of YJZYT actions remain to be established. The main objectives of this study were to clarify the effects of YJZYT on the TE and provide insights into the related mechanisms based on network pharmacology and molecular docking analyses.

Methods

Network pharmacology was employed to explore the main bioactive components and targets of YJZYT. TE-related genes were obtained from the Genecards database and screened for intersections with YJZYT. The Cytoscape 3.8.2 was used to build a "compounds-disease-targets" network and molecular docking analysis performed on key targets. The mechanism of action of YJZYT was further validated in vivo using a rat model.

Results

A total of 98 YJZYT active ingredients, 2409 thin endometrium-associated genes, and 186 common targets were obtained. Through topological analysis, 10 core objectives were screened. Data from the PPI network suggest that AKT1, TNF, VEGFA, IL-6, TP53, INS, ESR1, MMP9, ALB, and ACTB serve as key targets in the action of YJZYT on TE. PI3K-Akt, TNF, apoptosis, IL-17 and MAPK were established as the main functional pathways. Molecular docking analysis revealed high affinity of the active ingredients of YJZYT, specifically, ursolic acid, palbinone, stigmasterol, and beta-sitosterol, for TNF, VEGFA, IL-6, AKT, and MMP9. YJZYT improved endometrial recovery, promoted endometrial angiogenesis, and upregulated protein expression of VEGF, PI3K, AKT, and p-AKT in the TE rat model.

Conclusion

Network pharmacological and animal studies facilitated the prediction and validation of the active components and key targets of YJZYT potentially contributing to TE. Preliminary evidence from in vivo experiments showed that YJZYT promotes angiogenesis and thin endometrial repair via regulation of the PI3K/AKT pathway, providing a reference for further research.

Treatment options for endometrial hypoproliferation

PURPOSE OF REVIEW

Endometrial hypoproliferation refers to the failure of the endometrium to reach optimal thickness during fresh or frozen embryo transfer cycles in women undergoing infertility treatment with in-vitro fertilization (IVF). This review discusses the treatment options for endometrial hypoproliferation.

RECENT FINDINGS

Apart from factors related to the embryo quality, ultrasonographic findings associated with the endometrium, such as endometrial thickness, endometrial pattern and subendometrial blood flow, are considered key factors associated with the outcome of assisted reproductive treatment. To date, a consensus has not been reached regarding the definition of thin endometrium, while thresholds of 6, 7 or 8 mm have been used in the literature. Strategies to increase endometrial thickness can be reviewed in three groups: endocrine approaches, vitamins & supplements, and new experimental therapeutic interventions. Some of the recently introduced experimental therapeutic interventions such as platelet-rich plasma injection, stem cell treatment and tissue bioengineering are exciting potential therapies that need to be further studied.

SUMMARY

Despite a large number of publications on the topic, diagnosing and treating endometrial hypoproliferation remains a challenge. Well designed studies are needed to establish a widely accepted endometrial thickness cut-off value below which endometrial hypoproliferation is diagnosed and to generate meaningful data that would allow an evidence-based discussion of available therapeutic options with patients.

Nomogram for predicting the risk of preterm birth in women undergoing in vitro fertilization cycles

BACKGROUND

The aim of this study was to develop a nomogram for predicting the risk of preterm birth in women undergoing in vitro fertilization (IVF) cycles.

METHODS

A retrospective study of 4266 live birth cycles collected from January 2016 to October 2021 at the Center for Reproductive Medicine, First Hospital of Jilin University was performed. The sample size was sufficient based on the minimal ten events per variable (EPV) rule. The primary outcome of this study was preterm birth. The cycles were divided into the preterm birth group (n = 827) and the full-term delivery group (n = 3439). A nomogram was established based on the multivariate logistic regression analysis results. The area under the curve (AUC) was calculated to assess the prediction accuracy of the nomogram model. The calibration curve was used to measure the calibration of the nomogram.

RESULTS

Multivariate logistic regression analyses showed that female obesity or overweight (OR = 1.366, 95% CI: 1.111-1.679; OR = 1.537, 95% CI: 1.030-2.292), antral follicle count (AFC) of more than 24 (OR = 1.378, 95% CI: 1.035-1.836), multiple pregnancies (OR = 6.748, 95% CI: 5.559-8.190), gestational hypertension (OR = 9.662, 95% CI: 6.632-14.078) and gestational diabetes (OR = 4.650, 95% CI: 2.289-9.445) were the independent risk factors for preterm birth in IVF patients. The area under curve (AUC) under the receiver operating characteristic (ROC) curve in the prediction model was 0.781(95%CI: 0.763-0.799). The calibration curve of the nomogram showed that the prediction model had a good calibration.

CONCLUSIONS

We used five risk factors to conduct a nomogram to predict preterm birth rates for patients undergoing IVF cycles. This nomogram can provide a visual assessment of the risk of preterm birth for clinical consultation.

Intrauterine instillation of autologous platelet-rich plasma in infertile females with thin endometrium undergoing intrauterine insemination: an open-label randomized controlled trial

BACKGROUND

Thin endometrium in infertile female patients has always been a clinical challenge for the treating reproductive physicians.

OBJECTIVE

This study aimed to evaluate the effect of intrauterine instillation of autologous platelet-rich plasma on endometrial thickness and vascularity in infertile female patients with thin endometrium undergoing ovarian stimulation with intrauterine insemination.

STUDY DESIGN

This prospective randomized control study included 120 women undergoing ovarian stimulation with intrauterine insemination, aged between 21 and 37 years, with persistent thin endometrium (<7 mm) on ≥1 cycle in previous ovarian stimulation cycles, even after conventional treatment with estradiol valerate. The women were randomly assigned to study group A and control group B. Baseline endometrial thickness and endometrial vascularity were noted. Intrauterine instillation of autologous platelet-rich plasma was done on the day of trigger in group A, whereas estradiol valerate was given in group B. Another evaluation of endometrial parameters was done on the day of intrauterine insemination. The cycle was repeated for 3 cycles or until the pregnancy was achieved, whichever occurred earlier. Parameters were noted for both groups. Primary outcomes were the change in endometrial thickness and endometrial vascularity. Secondary outcomes were positive pregnancy rate and clinical pregnancy rate.

RESULTS

In group A, mean pre-platelet-rich plasma endometrial thickness was 4.66±0.79 mm, which significantly increased to 7.47±0.85 mm after platelet-rich plasma instillation (P<.05) after 3 cycles. This increase was significantly greater than that observed in group B. There was significant increase in endometrial vascularity in group A compared with group B (P<.05). The positive pregnancy rate and clinical pregnancy rate in group A were 23.73% and 18.64%, respectively, and significantly higher than those in group B.

CONCLUSION

Autologous platelet-rich plasma is a promising, easily procurable, and novel option for management of infertile females with thin endometrium not responding to conventional treatment. Using it in intrauterine insemination cycles can reduce costs and psychological burden of this subgroup of women by reducing the need for resorting to advanced options such as in vitro fertilization and surrogacy.

A comparison of special intrauterine balloons and intrauterine contraceptive devices in the treatment of intrauterine adhesions

PURPOSE

This study aimed to compare the efficacy of a special kind of intrauterine balloon (IUB) and that of an intrauterine contraception device (IUD) for patients with intrauterine adhesions (IUAs) after transcervical resection of adhesion (TCRA).

METHODS

In this retrospective cohort study, after TCRA, 31 patients received a special IUB, and 38 patients received an IUD. The Fisher exact test, logistic regression method, Kaplan-Meier method and Cox proportional hazards regression model were used for statistical analysis. A two-sided value of P < 0.05 was considered statistically significant.

RESULTS

The readhesion rate significantly differed between the IUB group and IUD group, at 15.39% and 54.06%, respectively (P = 0.002). For recurrent moderate IUA, patients in the IUB group had lower scores than patients in the IUD group (P = 0.035). There was a significant difference in the intrauterine pregnancy rate of IUA patients in the IUB group and IUD group after treatment, with rates of 55.56% and 14.29%, respectively (P = 0.015).

CONCLUSION

Patients in the special IUB group had better outcomes than those in the IUD group, which has a certain guiding significance for clinical work.

Agonist long protocol improves outcomes of vitrified-warmed embryo transfer in repeatedly thin endometrium

RESEARCH QUESTION

Does follicular stimulation using human menopausal gonadotrophin (HMG) after pituitary down-regulation by a GnRH agonist improve endometrial thickness (EMT) and clinical outcomes of frozen-thawed embryo transfer (FET; using vitrified-warmed embryos) in women with thin endometrium after intensified oestrogen administration (IOA)?

DESIGN

This was a retrospective study. A total of 627 patients attempted 683 FET cycles with at least one previous history of thin endometrium. None of the cycles reached over 7 mm EMT after using oral and vaginal oestradiol for more than 21 days (IOA protocol). A total of 129 cycles proceeded with FET, 305 cycles were cancelled, and 249 cycles involved administration of HMG following GnRH agonist pituitary down-regulation (GnRH agonist + HMG protocol) for further endometrial preparation.

RESULTS

EMT became significantly greater (7.18 ± 1.14 mm versus 6.13 ± 0.63 mm, P < 0.001) using GnRH agonist + HMG compared with previous IOA cycles, but this was not related to serum oestrogen concentrations. A total of 213 cycles after the GnRH agonist + HMG protocol proceeded with FET, showing a significantly increased clinical pregnancy rate, implantation rate and live birth rate compared with those after IOA.

CONCLUSIONS

The GnRH agonist + HMG protocol for endometrial preparation in FET cycles improves EMT in women with a thin endometrium after IOA and showed significantly better clinical outcomes than IOA. The authors suggest that the GnRH agonist + HMG protocol should be used for EMT that is less than 7 mm after there has been no optimal response to IOA.

Dysfunctional intercellular communication and metabolic signaling pathways in thin endometrium

Background: The endometrial thickness is a key factor for successful implantation. Thin endometrium is associated with lower implantation rate and pregnancy rate. Lacking of a better understanding for the cellular and molecular mechanisms of thin endometrium, managing patients with thin endometrium still represents a major challenge for clinicians. Methods: In this study, we combined four single-cell RNA sequencing (scRNA-seq) and one bulk sequencing (bulk-seq) data for thin endometrium to perform an integrated analysis for endometrial cells in proliferating phase. Cell proportion and differentially expressed genes (DEGs) were analyzed to determine the disease-specific cell type and signaling pathways. The cell-cell communication among cell types were inferred by "CellChat" to illustrate the differential intercellular communication under normal and thin endometrium conditions. GSEA and GSVA were applied to identify dysfunctional signals and metabolic pathways before and after thin endometrium. Results: Integration of scRNA-seq identified eight cell types. The proportion of stromal cells showed a significant difference between normal and thin endometrial tissue. The DEGs in diverse cell types revealed enriched pathways in a cell-specific manner. Aberrant cell-cell signaling transduction was found in almost all cell types, especially in immune cells and epithelial cells. Furthermore, dysfunctional metabolic signaling pathways were induced in a cell-type dependent way. The down-regulation of carbohydrate metabolism and nucleotide metabolism was observed and the energy metabolism switch was indicated. Conclusion: Conclusively, we discover dysfunctional signals and metabolic pathways in thin endometrium, providing insight into mechanisms and therapeutic strategies for the atrophic endometrium.

Human Umbilical Cord Mesenchymal Stem Cell-Derived Exosome Repairs Endometrial Epithelial Cells Injury Induced by Hypoxia via Regulating miR-663a/CDKN2A Axis

Aim

Thin endometrium remains a severe clinical challenge with no effective therapy to date. We aimed at exploring the role and molecular mechanism of human umbilical cord mesenchymal stem cell- (hucMSC-) derived exosomes (hucMSC-Ex) in repairing hypoxic injury of endometrial epithelial cells (EECs).

Methods

Exosomes were harvested from the conditioned medium of hucMSC and characterized using western blot, transmission electron microscopy (TEM), flow cytometry, and nanoparticle tracking analysis (NTA). EECs were subjected to hypoxic conditions before cocultured with hucMSC-Ex. Cell viability, apoptosis, and migration were determined with CCK-8, flow cytometry, and wound healing assay, respectively. Apoptosis/EMT-related proteins were detected by western blot. The miRNA profiling was determined by RNA sequencing. The expression of miR-663a and CDKN2A was measured by qRT-PCR. MiR-663a in EECs was overexpressed by transfecting with miR-663a mimics.

Results

Mesenchymal stem cells (MSCs) markers CD73, CD90, and CD106 were positively expressed in hucMSCs. Exosome isolated from hucMSC expressed CD63 and TSG101, and were 100-150 nm in diameter. HucMSC-Ex promoted cell proliferation inhibited by hypoxia. And hucMSC-Ex also inhibited hypoxia-induced apoptosis, migration, and EMT of EECs by upregulating the expression of Bcl-2 and E-cadherin and downregulating Bax and N-cadherin levels. Further, bioinformatics research found that hucMSC-Ex coculture can significantly upregulate the expression of miR-663a and decrease the expression of CDKN2A in hypoxia-induced EECs. Furthermore, miR-663a overexpression inhibited CDKN2A expression and increased the expression of Bcl-2 and E-cadherin in hypoxia-induced EECs.

Conclusions

HucMSC-Ex promoted cell proliferation, inhibited cell apoptosis, migration, and EMT in hypoxia-induced EECs, thereby alleviating hypoxia-induced EECs injury, which may be related to its regulation of miR-663a/CDKN2A expression. Our study indicated that hucMSC-Ex might benefit for repairing thin endometrium.

Incidence and risk factors for early pregnancy loss in women with first pregnancy undergoing in vitro fertilization-embryo transfer

Background

This study aimed to explore the incidence and influencing factors for early pregnancy loss (EPL) in infertility patients with first pregnancy undergoing in vitro fertilization (IVF) embryo transfer cycles in Jilin province, China.

Methods

A retrospective study of 2709 first pregnancy embryo transfer cycles collected from January 2016 to January 2021 was performed. The cycles were divided into the EPL group (n = 411) and the live birth group (n = 2298) according to the cycle outcomes.

Results

The EPL rate of the first-time pregnancies for infertility patients undergoing fresh/frozen-thaw embryo transfer cycle was 14.1%. Female patients aged 40 and older had increased odds of EPL compared to those under 35 (OR = 3.97, 95%CI: 2.80–7.55). Female patients with a body mass index (BMI) of 25 or greater were more likely to have EPLs than those in the normal BMI range (OR = 1.32, 95%CI: 1.03–1.70). The odds of EPL after frozen-thaw embryo transfer were higher than those after fresh embryo transfer (OR = 1.59, 95%CI: 1.11–2.27). A thin endometrium on the day of embryo transfer increased the odds of EPL (OR = 1.84, 95%CI: 1.01–3.33). Transferring more than two embryos had lower odds of EPL than single-embryo transfer (OR = 0.67, 95%CI: 0.50–0.90). Compared with other infertility diagnoses, tubal factor alone was associated with lower odds of EPL (OR = 0.72, 95%CI: 0.53–0.98).

Conclusions

The risk factors for EPL were age 40 and older, obesity, frozen-thaw cycle, thin endometrium, and non-isolated tubal factor.

Effect of new biological patch in repairing intrauterine adhesion and improving clinical pregnancy outcome in infertile women: study protocol for a randomized controlled trial

Background

Endometrial fibrosis caused by intrauterine adhesion (IUA) can lead to hypomenorrhea, amenorrhea, and even infertility and abortion. The postoperative recurrence rate of severe IUA remains high, giving rise to low pregnancy rates. An extracellular matrix (ECM) scaffold, a new biological material that can promote cell proliferation and differentiation at lesions, has been widely used in general surgery and neurosurgery. The present study applied ECM scaffolds in obstetrics and gynecology for the first time to improve endometrial fibrosis, repair severe IUA, and improve pregnancy outcomes for infertile patients.

Methods

This paper presents a prospective randomized single-blind controlled superiority study of infertile women aged ≤40 years with IUA. According to the scoring criteria for IUA established by the American Fertility Society, patients with moderate or severe IUA were randomized into two groups at a ratio of 1:1; patients in the experimental group were treated with an ECM scaffold (small intestinal submucosa [SIS]) + intrauterine balloon, while patients in the control group were treated with an intrauterine balloon only. A hysteroscopic examination of adhesion repair was performed again after 2 months of postoperative hormone replacement therapy. Endometrial tissue was sampled during the two operations, and immunohistochemistry was used to observe endometrial and microvascular proliferation. After thawing and resuscitation, a postoperative frozen embryo transfer was performed on the participants in both groups, and their endometrial thickness, intrauterine volume, endometrial vascularization flow index, endometrial flow index, and uterine artery blood flow resistance were evaluated by 3D ultrasonography. The rates of embryo implantation, clinical pregnancy, and early spontaneous abortion were observed.

Discussion

The ECM scaffold (SIS) + intrauterine balloon method was able to repair endometrial fibrosis and improve IUA. This new technique represents a novel treatment method for improving the pregnancy outcome of infertile patients with moderate/severe IUA.

Trial registration

Chinese Clinical Trial Register ChiCTR2100052027. Registered on October 14, 2021.

Characterization of Epigenetic and Molecular Factors in Endometrium of Females with Infertility

Infertility is one of the most rapidly increasing global health concerns of the 21st century. Embryo quality and endometrial thickness and receptivity are the main factors for successful embryo implantation and pregnancy development. Nevertheless, until now, there has been a lack of understanding about the regulation of human endometrium function and its structure. This raises the demand for more research of the human endometrium in these fields. In our study, we analyzed the genetic and epigenetic changes of endometrial tissue’s samples isolated from females admitted for treatment due to male infertility and females diagnosed with reproductive pathologies, who are preparing for assisted reproductive technologies procedures. Using real-time polymerase chain reaction method, we demonstrated that endometrium of females with reproductive pathology has significantly upregulated decidualization related genes HAND2, MUC1, CSF2, increased expression of angiogenesis related gene PDGFA, and increases of overall immune response and inflammation-related genes expression with significant changes of RELA and CXCL10 genes expression. Females with reproductive pathology have altered endometrium epigenetic regulation since expression of miRNAs—specifically, miRNA-34a, miRNA-223, and miRNA-125b—is lower in endometrium of females with reproductive pathology. Our findings suggest that the potential changes in genetic and epigenetic profile of endometrium from females with reproductive pathology could enrich the knowledge in the field of core biological knowledge and treatment of reproductive impairments.

Recent Advances in Treatment of Recurrent Spontaneous Abortion

Importance

Recurrent spontaneous abortion (RSA) is a distressing condition experienced by approximately 1% of women trying to conceive. However, the treatment of RSA is a challenge both for clinicians and patients.

Objective

The aim of this review is to discuss the medical and surgical approach to the management of RSA, including those caused by anatomical, genetic, male, infectious, endocrine, and immune factors.

Evidence Acquisition

A literature search using MeSH terms for each topic was undertaken using PubMed, supplemented by hand searching for additional references. Retrieved articles were reviewed, synthesized, and summarized.

Results

Available treatments target hypothetical risk factors for RSA, although the effectiveness of many treatment options is controversial. Intervention should depend on the benefit-to-risk ratio of the proposed treatment.

Conclusions and Relevance

The etiology of RSA is heterogeneous, and patients often lack specific clinical manifestations, which has hindered the progress in predicting and preventing RSA to some extent. Despite intensive workup, at least 50% of couples do not have a clear underlying pathology. In addition, an evidence-based treatment is not available in most patients even if abnormal test results are present. Many new treatment directions are also still actively exploring; empirical and combined multiple treatments are still the main methods.

Target Audience

Obstetricians and gynecologists, family physicians.

Learning Objectives

After completing this activity, the learner should be better able to describe common risk factors for RSA; formulate individualized treatment plans to improve pregnancy outcomes; and propose supportive treatment recommendations for patients with unclear causes.

Granulocyte colony-stimulating factor in reproductive-related disease: Function, regulation and therapeutic effect

Granulocyte colony-stimulating factor (G-CSF) is one of the cytokines which plays important roles in embryo implantation and normal pregnancy. At the maternal-fetal interface, G-CSF can be synthesized by multiple cells, and participates in regulation of trophoblast development, endometrial decidualization, placental metabolism and angiogenesis. Moreover, as an important medium of intercellular communication, G-CSF has also been shown to exert key roles in crosstalk between cellular components at the maternal-fetal interface. Recently, our study demonstrated that G-CSF derived from M2 macrophage could promote trophoblasts invasion and migration through activating PI3K/AKT/Erk1/2 pathway, thereby involving in normal pregnancy program. Herein, we will summarize the role and regulation of G-CSF in normal pregnancy and reproductive-related disease, and the clinical applications of G-CSF in patients undergoing in vitro fertilization with thin endometrium, repeated implantation failure, and women suffered with recurrent spontaneous abortion.

Evidence for the effectiveness of immunologic therapies in women with subfertility and/or undergoing assisted reproduction

Implantation is a critical step in the establishment of a successful pregnancy, depending on a complex immune-endocrine dialogue between the developing embryo and maternal endometrium. Research suggests that altered immunity in the maternal decidua results in implantation impairment and failure. Immunomodulatory drugs have, thus, been widely used in assisted conception to aid embryo implantation, despite an absence of consensus on their effectiveness and safety. We conducted a systematic review and meta-analysis of interventional studies investigating the use of immunomodulators in women undergoing assisted reproduction. Evidence was uncertain of an effect for most of the included interventions, owing to heterogeneous findings and a paucity of high-quality studies. For certain patient subgroups, however, the use of specific immunomodulatory therapies may offer some benefit. There is a need for further large randomized controlled trials to corroborate these findings.

Effectiveness of phosphodiesterase type 5 inhibitors on the treatment of thin endometrium and pregnancy outcomes: An systematic review

Phosphodiesterase type 5 (PDE5) inhibitors are thought to play a role in increasing endometrial thickness and increasing the success rate of pregnancy outcomes. This study was done to investigate the effects of PDE5 inhibitors on infertile women with thin endometrium and pregnancy outcomes. In this systematic review, all randomized controlled trials (RCTs) and observational studies were retrieved from databases including Institute for Scientific Information (ISI), PubMed, and Scopus by interesting keywords. A checklist was designed to collect necessary data and pregnancy outcomes, and the required items were recorded. PDE5 inhibitors through various mechanisms such as induction of vasodilatory effect through the effect on NO/cGMP signaling on vascular smooth muscle, through regulating cells proliferation and induction angiogenesis by increasing the expression of tumor suppressor factor (p53), and vascular endothelial growth factor A (VEGF-A) and downregulating inflammation by downregulating proinflammatory cytokines, affect endometrial thickness that eventually increases and pregnancy outcomes. Although PDE5s inhibitors increase endometrial thickness by different mechanisms, especially in women with thin endometrial, this does not necessarily mean that they induce a positive effect in all situations. However, their positive effects on pregnancy outcome may be affected by the time of administration, type of infertility treatment, underlying diseases such as pelvic disorders and inflammation. So in this regard, there are still ambiguous aspects that required further RCTs study in this area.

The Role of Endometrial Stem/Progenitor Cells in Recurrent Reproductive Failure

Recurrent implantation failure (RIF) and recurrent pregnancy loss (RPL), collectively referred to as recurrent reproductive failure (RRF), are both challenging conditions with many unanswered questions relating to causes and management options. Both conditions are proposed to be related to an aberrant endometrial microenvironment, with different proposed aetiologies related to a restrictive or permissive endometrium for an invading embryo. The impressive regenerative capacity of the human endometrium has been well-established and has led to the isolation and characterisation of several subtypes of endometrial stem/progenitor cells (eSPCs). eSPCs are known to be involved in the pathogenesis of endometrium-related disorders (such as endometriosis) and have been proposed to be implicated in the pathogenesis of RRF. This review appraises the current knowledge of eSPCs, and their involvement in RRF, highlighting the considerable unknown aspects in this field, and providing avenues for future research to facilitate much-needed advances in the diagnosis and management of millions of women suffering with RRF.

Influence of Maternal Age on the Relationship Between Endometrial Thickness and Ongoing Pregnancy Rates in Frozen-Thawed Embryo Transfer Cycles: A Retrospective Analysis of 2,562 Cycles

Background

In frozen-thawed embryo transfer (FET) cycles, endometrial thickness (EMT) has been used routinely as the main clinical monitoring index. However, the current findings are conflicting.

Method

This was a single-center retrospective study of 2,054 couples (2,562 cycles) who underwent FET (including cleavage stage embryos and blastocysts) between January 2017 and August 2020 in the reproductive centers of First Affiliated Hospital of Xinjiang Medical University. The primary outcome measure was the ongoing pregnancy rate (OPR); the secondary outcome was the clinical pregnancy rate.

Results

After stratified analysis and adjusting for confounders such as maternal age, duration of infertility, number of high-quality embryos transferred, endometrial preparation protocol, number of transfer cycles, and stages of embryo transferred, we found a curvilinear relationship between EMT and the OPR in women < 35 years of age. For women with EMT ≤ 8 mm, the OPR increased by 150% for cleavage stage embryo transfer for every 1 mm increase in the EMT; similarly, it increased by 97% for blastocyst stage FET. However, there was a linear relationship between EMT and OPR in women aged ≥ 35 years. When blastocysts were transferred, for every 1 mm increase in the EMT the OPR increased significantly by 12%. But OPR after frozen-thawed cleavage stage embryos transfer did not increase significantly with increased EMT.

Conclusions

Our study showed that the OPR increased significantly with increased EMT between young women aged < 35 years with EMT ≤ 8 mm and older women who underwent transfer of blastocysts.

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

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

Graphical abstract

Efficacy and safety of autologous adipose tissue-derived stromal vascular fraction in patients with thin endometrium: a protocol for a single-centre, longitudinal, prospective self-control study

INTRODUCTION

Endometrial thickness is an important parameter to evaluate endometrial receptivity. An appropriate endometrial thickness is necessary for both embryo implantation and maintaining normal pregnancy. Women with thin endometrium are one of the critical challenges in the clinic, and current therapeutic strategies for thin endometrium remain suboptimal. The stromal vascular fraction (SVF) derived from adipose tissue contains a variety of cells, mainly adipose-derived stem/stromal cells and adipose cells. Recently, adipose tissue-derived SVF showed tremendous potential for treating thin endometrium due to its capacity to repair and regenerate tissues. The application of SVF in animal models for treating thin endometrium has been investigated. However, limited evidence has demonstrated the efficacy and safety of autologous SVF in patients with thin endometrium.

METHODS AND ANALYSIS

This study is a single-centre, longitudinal, prospective self-control study to investigate the preliminary efficacy and safety of autologous SVF in improving the pregnancy outcome of infertile patients with thin endometrium. Thirty patients diagnosed with thin endometrium will be recruited based on the inclusion and exclusion criteria. The SVF suspension will be transferred into the uterine cavity via an embryo transfer catheter. Then, comparisons between pretreatment and post-treatment will be analysed, and the outcomes, including endometrial thickness, menstrual volume and duration, frequency and severity of adverse events and early pregnancy outcomes, will be measured within a 3-month follow-up, while late pregnancy outcomes and their offspring will be followed up via telephone for 2 years. The proportion of patients with improved symptoms will be calculated and compared.

ETHICS AND DISSEMINATION

This study was approved by the Ethics Committee of Peking University Third Hospital (reference number: REC2020-165). Written informed consent will be provided for patients before being included. The results will be presented at academic conferences and a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ChiCTR2000035126.

Synergistic regenerative therapy of thin endometrium by human placenta-derived mesenchymal stem cells encapsulated within hyaluronic acid hydrogels

Background

Thin endometrium is a primary cause of defective endometrial receptivity, resulting in infertility or recurrent miscarriage. Much effort has been devoted toward regenerating thin endometrium by stem cell-based therapies. The human placenta-derived mesenchymal stem cells (HP-MSCs) are emerging alternative sources of MSCs with various advantages. To maximize their retention inside the uterus, we loaded HP-MSCs with cross-linked hyaluronic acid hydrogel (HA hydrogel) to investigate their therapeutic efficacy and possible underlying mechanisms.

Methods

Ethanol was injected into the mice uterus to establish the endometrium-injured model. The retention time of HP-MSCs and HA hydrogel was detected by in vivo imaging, while the distribution of HP-MSCs was detected by immunofluorescence staining. Functional restoration of the uterus was assessed by testing embryo implantation rates. The endometrial morphological alteration was observed by H&E staining, Masson staining, and immunohistochemistry. In vitro studies were further conducted using EdU, transwell, tube formation, and western blot assays.

Results

Instilled HP-MSCs with HA hydrogel (HP-MSCs-HA) exhibited a prolonged retention time in mouse uteri than normal HP-MSCs. In vivo studies showed that the HP-MSCs-HA could significantly increase the gland number and endometrial thickness (P < 0.001, P < 0.05), decrease fibrous area (P < 0.0001), and promote the proliferation and angiogenesis of endometrial cells (as indicated by Ki67 and VEGF, P < 0.05, P < 0.05, respectively) in mice injured endometrium. HP-MSCs-HA could also significantly improve the embryo implantation rate (P < 0.01) compared with the ethanol group. Further mechanistic study showed the paracrine effects of HP-MSCs. They could not only promote the proliferation and migration of human endometrial stromal cells via the JNK/Erk1/2-Stat3-VEGF pathway but also facilitate the proliferation of glandular cells via Jak2-Stat5 and c-Fos-VEGF pathway. In turn, the increased VEGF in the endometrium promoted the angiogenesis of endothelial cells.

Conclusion

Our study suggested the potential therapeutic effects and the underlying mechanisms of HP-MSCs-HA on treating thin endometrium. HA hydrogel could be a preferable delivery method for HP-MSCs, and the strategy represents a promising therapeutic approach against endometrial injury in clinical settings.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02717-2.

Down-regulation of PBK inhibits proliferation of human endometrial stromal cells in thin endometrium

BACKGROUND

Thin endometrium (TE) is a challenging clinical issue in the reproductive medicine characterized by inadequate endometrial thickness, poor response to estrogen and no effective treatments currently. At present, the precise pathogenesis of thin endometria remains to be elucidated. We aimed to explore the related molecular mechanism of TE by comparing the transcriptome profiles of late-proliferative phase endometria between TE and matched controls.

METHODS

We performed a bulk RNA-Seq (RNA-sequencing) of endometrial tissues in the late-proliferative phase in 7 TE and 7 matched controls for the first time. Differential gene expression analysis, gene ontology enrichment analysis and protein-protein interactions (PPIs) network analysis were performed. Immunohistochemistry was used for molecular expression and localization in endometria. Human endometrial stromal cells (HESCs) were isolated and cultured for verifying the functions of hub gene.

RESULTS

Integrative data mining of our RNA-seq data in endometria revealed that most genes related to cell division and cell cycle were significantly inhibited, while inflammation activation, immune response and reactive oxygen species associated genes were upregulated in TE. PBK was identified as a hub of PPIs network, and its expression level was decreased by 2.43-fold in endometria of TE patients, particularly reduced in the stromal cells, which was paralleled by the decreased expression of Ki67. In vitro experiments showed that the depletion of PBK reduced the proliferation of HESCs by 50% and increased the apoptosis of HESCs by 1 time, meanwhile PBK expression was inhibited by oxidative stress (reduced by 76.2%), hypoxia (reduced by 51.9%) and inflammatory factors (reduced by approximately 50%). These results suggested that the insufficient expression of PBK was involved in the poor endometrial thickness in TE.

CONCLUSIONS

The endometrial transcriptome in late-proliferative phase showed suppressed cell proliferation in women with thin endometria and decreased expression of PBK in human endometrial stromal cells (HESCs), to which inflammation and reactive oxygen species contributed.

Transplantation of umbilical cord-derived mesenchymal stem cells promotes the recovery of thin endometrium in rats

The endometrium plays a critical role in embryo implantation and pregnancy, and a thin uterus is recognized as a key factor in embryo implantation failure. Umbilical cord mesenchymal stem cells (UC-MSCs) have attracted interest for the repair of intrauterine adhesions. The current study investigated the repair of thin endometrium in rats using the UC-MSCs and the mechanisms involved. Rats were injected with 95% ethanol to establish a model of thin endometrium. The rats were randomly divided into normal, sham, model, and UC-MSCs groups. Endometrial morphological alterations were observed by hematoxylin-eosin staining and Masson staining, and functional restoration was assessed by testing embryo implantation. The interaction between UC-MSCs and rat endometrial stromal cells (ESCs) was evaluated using a transwell 3D model and immunocytochemistry. Microarray mRNA and miRNA platforms were used for miRNA-mRNA expression profiling. Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) analyses were performed to identify the biological processes, molecular functions, cellular components, and pathways of endometrial injury and UC-MSCs transplantation repair and real-time quantitative reverse transcription PCR (qRT-PCR) was performed to further identify the expression changes of key molecules in the pathways. Endometrium thickness, number of glands, and the embryo implantation numbers were improved, and the degree of fibrosis was significantly alleviated by UC-MSCs treatment in the rat model of thin endometrium. In vitro cell experiments showed that UC-MSCs migrated to injured ESCs and enhanced their proliferation. miRNA microarray chip results showed that expression of 45 miRNAs was downregulated in the injured endometrium and upregulated after UC-MSCs transplantation. Likewise, expression of 39 miRNAs was upregulated in the injured endometrium and downregulated after UC-MSCs transplantation. The miRNA-mRNA interactions showed the changes in the miRNA and mRNA network during the processes of endometrial injury and repair. GO and KEGG analyses showed that the process of endometrial injury was mainly attributed to the decomposition of the extracellular matrix (ECM), protein degradation and absorption, and accompanying inflammation. The process of UC-MSCs transplantation and repair were accompanied by the reconstruction of the ECM, regulation of chemokines and inflammation, and cell proliferation and apoptosis. The key molecules involved in ECM-receptor interaction pathways were further verified by qRT-PCR. Itga1 and Thbs expression decreased in the model group and increased by UC-MSCs transplantation, while Laminin and Collagen expression increased in both the model group and MSCs group, with greater expression observed in the latter. This study showed that UC-MSCs transplantation could promote recovery of thin endometrial morphology and function. Furthermore, it revealed the expression changes of miRNA and mRNA after endometrial injury and UC-MSCs transplantation repair processed, and signaling pathways that may be involved in endometrial injury and repair.

Endometrial thickness is associated with low birthweight in frozen embryo transfer cycles: A retrospective cohort study of 8,235 singleton newborns

OBJECTIVE

To explore the association between endometrial thickness (EMT) and adverse neonatal outcomes in frozen in vitro fertilization/intracytoplasmic sperm injection-embryo transfer (IVF/ICSI-ET) cycles.

METHODS

This retrospective study involved a total of 8,235 women under the age of 35 years who underwent IVF/ICSI cycles and received frozen embryo transfer (FET) at a tertiary-care academic medical from January 2015 to December 2019, resulting in a live singleton newborn. Patients were categorized into three groups depending on EMT: ≤7.5 mm, 7.5-12 mm and >12 mm. The primary outcome was low birthweight (LBW). The secondary outcomes were preterm birth (PTB), small-for-gestational age (SGA), large-for-gestational age (LGA) and high birthweight (HBW).

RESULTS

Compared with EMT >7.5-12 mm group, the risk of being born LBW was statistically significantly increased in the EMT ≤7.5 mm group (adjusted odds ratio [aOR] 2.179; 95% confidence interval [CI], 1.305-3.640; P=.003), while dramatically decreased in the EMT >12 mm group (aOR 0.584; 95% CI, 0.403-0.844; P=.004). Moreover, newborn gender and pregnancy complications were all independent predictors for LBW. Furthermore, a significant decrease in birthweight was found in the EMT ≤7.5 mm group as compared with EMT >7.5-12 mm group and EMT >12 mm group (3,239 ± 612 vs. 3,357 ± 512 and 3,374 ± 479 g, respectively), and similar result was found in term of gestational age (38.41 ± 2.19 vs. 39.01 ± 1.68 and 39.09 ± 1.5 weeks, respectively).

CONCLUSIONS

After frozen IVF/ICSI-ET, EMT ≤7.5 mm is independently associated with increased risk of LBW among women with singleton newborns. Therefore, we suggest that women with EMT ≤7.5 mm after achieving pregnancy by IVF/ICSI-ET treatment should warrant more attention to reduce the risk of delivering a LBW newborn.

Human menstrual blood-derived mesenchymal stem cells regulation of the EGF/Ras p21 pathway as a potential therapeutic target for thin endometrium

Background

Human infertility is caused by many factors, among which thin endometrium is the main reason for poor embryo implantation. Currently, stem cell therapy could be a potential approach in treating human endometrial disorder like thin endometrium. In this study, we aimed to explore the influence of menstrual stem cells from non-thin endometrium (NTE-MenSCs) and thin endometrium (TE-MenSCs) on the phenotype of endometrial epithelial cells (EECs).

Methods

The MenSCs were isolated from women with and without thin endometria, characterized and co-cultured with the EECs. The expression of cytokeratin 7 (CK7) was verified by immunofluorescence while the detection stem cell markers was determined flow cytometry. Osteogenic and adipogenic differentiation were induced in appropriate media. The quantitative real-time PCR and western blotting were respectively used for detecting the mRNA and protein expression levels, respectively. The CCK-8 assay was used for cell viability analysis whereas ELISA was used for the detection of cytokine levels.

Results

The results showed that the co-culture of NTE-MenSCs or TE-MenSCs and EECs promoted the proliferation, migration, and angiogenesis of endothelial progenitor cells differently. Furthermore, the TE-MenSCs promoted the expression of inflammation, vascularized adipose, and extracellular matrix related proteins. The epidermal growth factor (EGF)/Ras p21 pathway was found to mediate the influence of MenSCs on EECs.

Conclusions

These findings are vital in that they may promote stem cell therapy of thin endometrium and enable embryo implantation in humans with thin endometrium.

Multiple regression analysis of perinatal conditions, physical development, and complications in assisted reproduction singletons

BACKGROUND

There is no clear clinical conclusion on whether assisted reproductive technology (ART) increases maternal and child risk and affects infant birth and development. This study aimed to perform a multiple regression analysis of the perinatal maternal and infant conditions in an assisted reproductive singleton pregnancy and the physical development and complications of such infants at 6 months old.

METHODS

This study enrolled 145 singleton pregnant women who were admitted to Luohe Central Hospital between December 2017 and December 2019 to undergo in vitro fertilization and embryo transfer as a research group, and 160 singleton pregnant women who were naturally conceived at the same time and delivered at our hospital were selected as the control group. The relevant data of the patients were collected, and the perinatal conditions, neonatal complications, physical development and NBN score of infants aged 6 months were compared between the two groups. Multivariate logistic regression was used to analyze risk factors for perinatal complications in assisted reproduction singleton pregnancy.

RESULTS

The incidence of complications in the perinatal period in the study group was significantly higher than that in the control group (P<0.05). However, there was no significant difference in the incidence of complications such as very low birth weight, respiratory distress, neonatal hemolysis, hyperbilirubinemia, hypoglycemia, infectious pneumonia and neonatal asphyxia between the two groups (P>0.05). Likewise, at 6 months of age, the infants in the research group showed no significant difference to the control group in physical development indicators, including weight, head circumference, body mass index, height and NBN score (P>0.05). The analysis of the unconditional multivariate logistic regression model revealed hypertension during pregnancy, placental previa, premature membrane rupture, gestational age <32 weeks, and very low birth weight as risk factors that affect perinatal complications in patients with assisted reproductive singleton pregnancy (P<0.05).

CONCLUSIONS

The incidence of complications in perinatal patients with assisted reproductive singleton pregnancy is higher than that of natural singleton pregnancy, but there is no significant difference in physical development, NBN score and complications of 6 months old infants.

Endometrial Receptivity Testing and Therapy in Assisted Reproductive Treatment

Assisted reproductive treatment (ART) gave numerous couples the chance to have their biological child. Improvement in laboratory and culture conditions allows for selection of embryos with the best developmental potential, although replacement of these top-quality embryos does not, however, guarantee reproductive success. Endometrial receptivity is essential for pregnancy establishment and may be the limiting factor for the observed pregnancy rates with ART. Multiple modalities have been in use to assess endometrial receptivity, with ultrasound assessment of the endometrial morphology most commonly used due to its noninvasive nature and availability. Utilization of various "omics" increases our understanding of endometrial receptivity and selectivity; however, significantly more work is required to develop clinically relevant and validated tests of endometrial receptivity and treatments which could improve a suboptimal endometrial milieu. Current evidence for and against use of various tests of endometrial receptivity in women undergoing ART is presented in this article.

Effect of sildenafil citrate on treatment of infertility in women with a thin endometrium: a systematic review and meta-analysis

OBJECTIVE

Endometrial thickness is a prognostic factor for successful pregnancy. This meta-analysis aimed to examine the role of sildenafil citrate on infertile women with a thin endometrium.

METHODS

Two investigators independently searched the literature on sildenafil citrate and infertile women with a thin endometrium from PubMed, EMBASE, and the Cochrane Controlled Trials Register Database from inception to January 2019.

RESULTS

Nine studies involving 1452 patients were included for analysis in our study. We found that endometrial thickness in patients who received sildenafil citrate was significantly higher than that in the control group (placebo or no treatment) (weighted mean difference: 1.22; 95% confidence interval [CI]: 1.07-1.38). The radial artery resistance index was significantly lower (weighted mean difference: -0.12; 95% CI: -0.17 to -0.06), and the clinical pregnancy rate (risk ratio: 1.31; 95% CI: 1.11-1.53) and biochemical pregnancy rate (risk ratio: 1.45; 95% CI: 1.11-1.89) were significantly higher in the sildenafil citrate group compared with the control group.

CONCLUSION

Sildenafil citrate is effective in improving endometrial thickness, the clinical pregnancy rate, and the biochemical pregnancy rate in women who have a thin endometrium. This treatment is a potential therapeutic intervention for a thin endometrium.

The impact of granulocyte colony-stimulating factor (G-CSF) on thin endometrium of an animal model with rats

MATERIALS AND METHODS

After forming of the thin endometrium by uterine injection of 0.2 ml 96% ethyl alcohol to the rats, five days of subcutaneous injections of 40 μg/kg G-CSF or saline were given. Endometrial thickness, immunohistochemically expression of vascular endothelial growth factor receptor-2 (VEGF-R2), proliferative cell nuclear antigen (PCNA) and fibronectin apoptosis with TUNEL method were compared in specimens among four groups of post-model rats.

RESULTS

Endometrial thickness was significantly improved in thin but not in normal endometrium group with GCSF when compared to saline injection. Stromal and glandular epithelial expression of PCNA and pericapillary VEGF-R2 was significantly increased, and apoptosis was significantly decreased with G-CSF. Although fibronectin was also increased with G-CSF in the thin endometrium, the difference was non-significant. In further, G-CSF decreased apoptotic cells and increased expression of PCNA when compared to saline injection in normal endometrium.

CONCLUSIONS

G-CSF improves endometrial thickness, proliferation, angiogenesis and DNA fragmentation in thin endometrium.

Electroacupuncture Improves Pregnancy Outcomes in Rats with Thin Endometrium by Promoting the Expression of Pinopode-Related Molecules

A thin endometrium affects the success of assisted reproduction due to low endometrial receptivity. Acupuncture improves endometrial receptivity and promotes the formation of pinopodes, the ultrastructure marker implantation window. However, the specific underlying mechanisms remain unclear. In this study, the efficacy of acupuncture treatment and its underlying mechanism were investigated by analyzing pregnancy rate, pinopode formation, and related molecular markers in thin endometrium model rats. Absolute ethanol (95%) was injected into the uteruses of female Sprague-Dawley rats to construct a thin endometrium model. In this model, acupuncture stimulation at EX-CA1, SP6, and CV4 ameliorated the pregnancy rate. Significantly increased embryo implantation, endometrial thickness, numbers of glands, and blood vessels were observed in the electroacupuncture (EA) group compared to the model group. The number of pinopodes in the EA group was abundant, with a shape similar to that of the control group. Additionally, significantly higher expression levels of pinopode-related markers, including integrin αvβ3, homeobox A10 (HOXA10), heparin-binding EGF-like growth factor (HBEGF), estrogen receptor alpha (ERα), and progesterone receptor (PR), were observed in the EA group than those in the model group. In conclusion, EA had a positive effect on the endometrial receptivity of thin endometrium model rats by improving pinopode formation through multiple molecular targets.

Meta-analysis of the embryo freezing transfer interval

BACKGROUND

The decision of whether frozen embryo transfer (FET) should be performed in the cycle immediately after OPU or at least one cycle later is controversial. FET could improve pregnancy rates in IVF; however, how much time is needed for the endometrium to return to optimal receptivity after ovarian stimulation is not known.

METHODS

Electronic search in MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials to identify studies providing data on the influence of the interval between embryo freezing (or OPU) and FET in FET cycles published between January 1, 2007, and February 1, 2020.

MAIN FINDINGS

Data analyzed indicated that in the immediate FET cycles, there was a trend to an increased biochemical pregnancy rate (RR = 1.08; CI = 1.00-1.18), whereas the clinical pregnancy rate was somewhat higher, but without reaching statistical significance (RR = 1.07; CI = 0.99-1.15). The live birth rate was similar in the two groups (RR = 1.05; CI = 0.95-1.15), as was the implantation rate (RR = 0.98; CI = 0.83-1.16). Stratifying by embryo stage or FET type (freeze-all or FET after failed fresh transfer) showed no differences.

CONCLUSION

Systematically delaying FET does not offer benefits to IVF outcomes. In addition, immediate transfer is associated with a nonsignificant trend to better clinical pregnancy rate and it also avoids the psychological effects of prolonging the stress on prospective parents.

Effectiveness of electroacupuncture for thin endometrium in infertile women: study protocol for a single-blind, randomized controlled trial

BACKGROUND

Thin endometrium negatively impacts the reproductive function. Current treatments for thin endometrium do not always improve endometrial receptivity. Preliminary evidence suggests that electroacupuncture could have potential therapy for thin endometrium in infertile women. Thus, this randomized controlled trial was designed to test whether electroacupuncture can improve endometrial receptivity in infertile women with thin endometrium.

METHODS

This study is a randomized, single-blinded, controlled, clinical trial. A total of 142 eligible patients will be recruited and randomly assigned to the electroacupuncture (EA) group or the sham electroacupuncture (SEA) group in a 1:1 ratio. Participants will receive 36 sessions over three menstrual cycles (12 weeks in total), with the same acupoint prescription. The primary outcome of this trial is endometrial thickness in the midluteal phase. The secondary outcomes include endometrial pattern, resistance index (RI) and pulsatility index (PI) of bilateral uterine artery and endometrium blood flow, serum estradiol (E2) and progesterone (P), and pregnancy rate. The pregnancy rate will be evaluated during a 6-month follow-up after completion of the trial. All other outcomes will be evaluated before treatment, during the treatment of 1st, 2nd, and 3rd menstrual cycle, and 6 months after treatment.

DISCUSSION

If the outcome confirms the effectiveness of electroacupuncture for thin endometrium in infertile women, this treatment will be proposed for application in clinical practice.

TRIAL REGISTRATION

Chinese Clinical Trials Registry ChiCTR2 000029983. Registered on 18 February 2020.

Decreased Endometrial Thickness Is Associated With Higher Risk of Neonatal Complications in Women With Polycystic Ovary Syndrome

PURPOSE

To evaluate the association of endometrial thickness (EMT) with obstetric and neonatal outcomes in women with polycystic ovary syndrome (PCOS).

METHODS

A total of 1755 subfertile PCOS women with singleton livebirths after frozen-thawed embryo transfer were included between January 2009 and September 2019. Main obstetric outcomes were hypertensive disorders in pregnancy and abnormal placentation. Main neonatal outcomes were preterm birth (PTB), low birthweight (LBW) and small-for-gestational age (SGA). Crude and adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were estimated by univariate and multivariate logistic regression analyses.

RESULTS

Each millimeter decrease in EMT was related to a 9% (adjusted OR 1.09, 95% CI 1.00-1.19; P = 0.053), 14% (adjusted OR 1.14, 95% CI 1.02-1.28; P = 0.002) and 22% (adjusted OR 1.22, 95% CI 1.07-1.38; P = 0.003) higher risk of PTB, LBW and SGA, respectively. Compared to women with EMT >13 mm, women with EMT ≤8 mm also had significantly higher risk of PTB (adjusted OR 3.79, 95% CI 1.53-9.39; P = 0.004), LBW (adjusted OR 4.33, 95% CI 1.39-13.50; P = 0.012) and SGA (adjusted OR 6.38, 95% CI 1.78-22.83; P = 0.004). These associations remained consistent in further subgroup analysis by endometrial preparation regimen and in sensitivity analyses among nulligravida women or women without adverse obstetric outcomes. No significant differences were found in the incidence of several pregnancy complications across EMT categories.

CONCLUSION

Decreased EMT was independently associated with increased risk of PTB, LBW and SGA in women with PCOS.

Mesenchymal stem cells for restoring endometrial function: An infertility perspective

BACKGROUND

Mesenchymal stem cells (MSCs) can be derived from several tissues such as bone marrow, placenta, adipose tissue, or endometrial tissue. MSCs gain a lot of attention for cell-based therapy due to their characteristics including differentiation ability and immunomodulatory effect. Preclinical and clinical studies demonstrated that MSCs can be applied to treat female infertility by improving of the functions of ovary and uterus. This mini- review focuses on the current study of treatment of endometrial infertility by using MSCs.

METHODS

The present study performed a literature review focusing on the effect of MSCs for treatment of women infertility caused by endometrial dysfunction.

RESULTS

Bone marrow-, umbilical cord-, adipose-, amniotic-, and menstruation-derived MSCs enhance endometrial cell proliferation, injury repairs as well as reducing scar formation. The beneficial mechanism probably via immunomodulatory, cell differentiation, stimulates endometrial cell proliferation and down-regulation of fibrosis genes. The major advantage of using MSCs is to improve endometrial functions resulting in increased implantation and pregnancy.

CONCLUSIONS

MSCs exhibit a potential for endometrial infertility treatment. Adipose- and menstruation-derived stem cells show advantages over other sources because the cells can be derived easily and do not causes graft rejection after autologous transplantation.

Application of autologous endometrial mesenchymal stromal/stem cells increases thin endometrium receptivity: a case report

Background

Pregnancy in cycles with the use of assisted reproductive technologies is possible only with the availability of good-quality embryos and a healthy receptive endometrium. The problem of lack of sensitivity of the endometrium is related to the syndrome of thin endometrium, which is caused by a number of factors. However, there is no single protocol for the treatment of this syndrome, the return/improvement of normal functionality of endometrial tissue, and obtaining the desired pregnancy.

Case presentation

We report a case of a 38-year-old Ukrainian woman with a number of unsuccessful tries at pregnancy in cycles with the use of assisted reproductive technologies. We describe a clinical case of the use of mesenchymal stem cells of the human endometrium for a woman with thin endometrial syndrome to increase its receptivity for pregnancy. The basic steps of patient management, protocol of sampling material for obtaining a cell product based on endometrial stem cells, their basic morphofunctional characteristics, and post-treatment procedures to obtain the desired pregnancy are described.

Conclusion

Application of autologous endometrial mesenchymal stem cells increases endometrial receptivity and the chance for pregnancy with use of assisted reproductive technologies.

Comparison of GnRH-a Prolonged Protocol and Short GnRH-a Long Protocol in Patients with Thin Endometrium for Assisted Reproduction: A Retrospective Cohort Study

Purpose

Gonadotrophin releasing hormone agonist (GnRH-a) is widely used for pituitary down-regulation and recruiting more follicles in assisted reproduction. However, no information is available on its value for patients with thin endometrial thickness.

Patients and Methods

This was a retrospective cohort study of 302 patients with endometrium <8 mm undergoing fresh embryo transfer at a fertility center of a university hospital from January 2016 and December 2018. In 148 cycles of the GnRH-a prolonged protocol, one depot of 3.75 mg GnRH-a was injected on day 2 of the menstrual cycle, while in 154 cycles of the short GnRH-a long protocol, 0.1 mg of GnRH-a was injected daily from the mid-luteal phase. The live birth rate and clinical pregnancy rate were compared between the two groups. Other outcome measures included the implantation rate, miscarriage rate, and characteristics of stimulation procedures.

Results

Live birth rates and clinical pregnancy rates were significantly higher in the GnRH-a prolonged protocol group than in the other group (36.5% vs 20.8%, P=0.002; 43.9% vs 28.2%, P=0.006, respectively). The live birth rate was significantly increased in the prolonged protocol group (crude OR: 2.190, 95% CI: 1.311, 3.660; adjusted OR: 2.458, 95% CI: 1.430, 4.224) compared with that in the reference group. The implantation rate of the former group was also significantly higher than that of the latter group (35.4% vs 15.9%, P=0.000). There was no significant difference in miscarriage rates between the two protocols. In terms of stimulation procedures, the GnRH-a prolonged protocol group required significantly higher Gn time (10.9 vs 9.5 days, P=0.000) and Gn consumption (2625.0 vs 2047.5 IU, P=0.000) than the short GnRH-a long protocol group.

Conclusion

The GnRH-a prolonged protocol in fresh embryo transfer cycles yielded better clinical outcomes of patients with thin endometrium than the short GnRH-a long protocol.

[Endometrial receptivity in assisted reproductive techniques: An aspect to investigate in embryo implantation failure]

Infertility affects between 8 and 12% of reproductive-age couples worldwide. Despite improvements in assisted reproductive techniques (ART), live birth rates are still limited. In clinical practice, imaging and microscopy are currently widely used, but their diagnostic effectiveness remains limited. In research, the emergence of innovative techniques named OMICS would improve the identification of the implantation window, while progressing in the understanding of the pathophysiological mechanisms involved in embryo implantation failures. To date, transcriptomic analysis seems to be the most promising approach in clinical research. The objective of this review is to present the results obtained with the different approaches available in clinical practice and in research to assess endometrial receptivity in patients undergoing ART.

In vitro fertilization add-ons for the endometrium: it doesn't add-up

The probability of live birth from an in vitro fertilization (IVF) cycle is modest. Many additional treatments (add-ons) are available which promise to improve the success of IVF. This review summarizes the current evidence for common IVF add-ons which are suggested to improve endometrial receptivity. Systematic reviews of randomized controlled trials and individual trials were included. Five add-ons were included: immune therapies, endometrial scratching, endometrial receptivity array, uterine artery vasodilation, and human chorionic gonadotropin instillation. The results suggest there is no robust evidence that these add-ons are effective or safe. Many IVF add-ons are costly, consuming precious resources which may be better spent on evidence-based treatments or further IVF. Large randomized controlled trials and appropriate safety assessment should be mandatory before the introduction of IVF add-ons into routine practice.