Insufficient Angiogenesis: Cause of Abnormally Thin Endometrium in Subfertile Patients?

Revitalizing female fertility: platelet-rich plasma - hype or hope?

Platelet-rich plasma (PRP) has gained popularity as an experimental tool in regenerative medicine, with potential applications in reproductive medicine. This review will assess the existing literature on the role of PRP in female fertility enhancement, focusing on ovarian rejuvenation and increased endometrial thickness. PRP is being explored as a treatment for recurrent implantation failure, primary ovarian insufficiency and poor ovarian response. While the influence of PRP on endometrial thickness and implantation success is postulated, its effectiveness remains the subject of debate due to protocol variability and unclear patient selection criteria. This narrative review includes 36 articles published before December 2022, and highlights the lack of comprehensive molecular studies examining the impact of PRP on reproductive capacity. This review underscores the importance of standardizing PRP preparation protocols in reproductive medicine. However, challenges persist, and there is a need for well-planned randomized controlled trials and a deeper understanding of the patient population that would gain the greatest benefit from PRP treatment. Clarifying these aspects is crucial to improve outcomes for low-prognosis patients undergoing assisted reproductive technology.

Comprehensive analysis of circRNA-miRNA-mRNA network related to angiogenesis in recurrent implantation failure

BACKGROUND

Abnormal endometrial blood flow causes a decrease in endometrial receptivity and is considered a relatively independent risk factor for recurrent implantation failure (RIF). This study aimed to explore the potentially functional circRNA-miRNA-mRNA network in RIF, and further explore its mechanism.

METHODS

Datasets were downloaded from the GEO database to identify differentially expressed circRNAs, miRNAs and mRNAs. The circRNA-miRNA-mRNA and PPI networks were constructed using Cytoscape 3.6.0 and the STRING database, the hub genes were identified with the cytoHubba plug-in, and a circRNA-miRNA-hub mRNA regulatory sub-network was constructed. Then, GO and KEGG pathway enrichment analyses of the hub genes were performed to comprehensively analyze the mechanism of hub mRNAs in RIF. Due to the results of circRNAs-miRNAs-hub mRNAs regulatory network, we verified the expression of circRNA_0001721, circRNA_0000714, miR-17-5p, miR-29b-3p, HIF1A and VEGFA in the RIF mouse model by qRT‒PCR and western blotting.

RESULTS

We initially identified 175 DEmRNAs, 48 DEmiRNAs and 56 DEcircRNAs in RIF associated with angiogenesis and constructed a circRNA-miRNA‒mRNA network and PPI network. We further identified six hub genes in the acquired network. Based on these genes, functional enrichment analysis revealed that the HIF-1 signaling pathway plays a vital role in endometrial angiogenesis in RIF. In addition, the interaction networks of circRNA_0001721/miR-17-5p/HIF1A and the circRNA_0000714/miR-29b-3p/VEGFA axis were predicted. In the RIF mouse model, circRNA_0001721, circRNA_0000714, HIF1A and VEGFA were down-regulated, whereas miR-17-5p and miR-29b-3p were up-regulated according to qRT‒PCR and western blotting.

CONCLUSION

This study revealed that the HIF-1 signaling pathway plays a vital role in endometrial angiogenesis in RIF. The circRNA_0001721/miR-17-5p/HIF1A and circRNA_0000714/miR-29b-3p/VEGFA axes might play a role in the pathogenesis of endometrial angiogenesis in RIF.

Effect of a novel copper chloride gel on endometrial growth and function in healthy volunteers

RESEARCH QUESTION

Does the application of a micro-dose of copper chloride gel increase endometrial production of vascular endothelial growth factor (VEGF) without compromising endometrial function or producing embryo toxicity?

DESIGN

An estimate of optimal dose was made based on cell culture studies. Ten healthy participants received an initial uterine application of placebo gel, followed by copper chloride gel (37.5 μM, 75 μM, or 150 μM dose) in a later hormone replacement cycle. Endometrial biopsies (day 5.5 luteal) and pelvic ultrasound were carried out during each cycle to evaluate endometrial function and growth. Uterine fluid was assessed for residual copper levels on the day of biopsy, and copper chloride gel underwent mouse embryos assay assessment for potential embryo toxicity.

RESULTS

The copper gel significantly increased endometrial VEGF expression (quantitative polymerase chain reaction), and also increasing endometrial thickness by an average of 2.2 mm compared with matched control cycles. The copper gel did not adversely affect endometrial morphology or maturation (histological dating and molecular receptivity testing), and mouse embryos assay studies showed no evidence of embryo toxicity. Furthermore, uterine cavity flush samples mostly lacked copper, with only negligible amounts present in one sample.

CONCLUSION

Applying copper chloride gel to the uterine cavity upregulated endometrial VEGF and significantly increased endometrial thickness and volume. No adverse effects on the endometrium or embryos were observed. Copper chloride gels show promise for treating suboptimal endometrial thickness if the results of this study are confirmed by larger randomized controlled trials.

Estrogens improve the pregnancy rate in cattle: A review and meta-analysis

Estrogens have proven to be effective in bovine estrus induction protocols. Considering the extensive use of these products in large-scale estrus synchronization, the primary objective of the present study was to assess their effects on pregnancy rate (PR) using a meta-analysis approach. A total of 797 papers were screened from three major databases (PubMed, Web of Science, Scopus). Sixty-one studies were eligible for inclusion in the meta-analysis. The pregnancy status (success or failure) at 30 days post-insemination was considered as the effect size data. The odds ratios (OR) of PR were evaluated by considering the effects of estrogens in groups with or without estrogen intervention. The impact of estrogen (including factors such as type, dose, and time of administration) and animal characteristics (such as breed, type, and parity) was taken into account when assessing the effectiveness of estrogen response as PR. The results showed an OR of 1.25 (95% CI: 1.15-1.36; P = 0.000) for PR in animals that received estrogen compared to cattle that did not receive estrogen. Estradiol benzoate (OR = 1.3) and estradiol cypionate (OR = 1.2), with doses ranging from 1 to 3 mg (OR = 1.13-1.7), significantly increased the OR of PR. In terms of PR, beef cattle exhibited a higher odds ratio (OR = 1.4; P = 0.000) compared to dairy cattle (OR = 1.1; P = 0.09). The administration of estrogens in the estrus synchronization protocol significantly improved PR in both artificial insemination (OR = 1.2; P = 0.000) and embryo transfer (OR = 1.3; P = 0.033) programs. In summary, incorporating estrogens into estrus induction protocols led to an enhancement of the OR of PR among cattle.

The effect of previous induced abortion history on the assisted reproduction outcomes

PURPOSE

To study whether the history of induced abortion has an effect on the assisted reproduction outcomes in patients undergoing in vitro fertilization-embryo transfer (IVF-ET).

METHODS

3045 patients who underwent IVF-ET in the Department of Human Reproductive Center of Renmin Hospital from January 2017 to June 2021. They were divided into two groups according to whether there was a history of induced abortion in the past, and the outcomes were compared between the two groups.

RESULTS

The clinical pregnancy rate in the group with induced abortion history was lower than that in the group without induced abortion history (63.1% vs 67.1%), but the difference was not statistically significant (P = 0.059). The spontaneous abortion rate in the group with induced abortion history was higher than that in the group without induced abortion history (14.9% vs 11.2%) (P = 0.044). The live birth rate in the group with induced abortion history was lower than that in the group without induced abortion history (52.8% vs 59.0%) (P = 0.006). Stepwise logistic regression analysis showed that endometrial thickness (OR = 0.928, 95% CI = 0.886 ~ 0.972, P = 0.002) and live birth rate (OR = 0.682, 95% CI = 0.495 ~ 0.939, P = 0.019) were negatively correlated with induced abortion history. The rate of spontaneous abortion (OR = 1.452, 95% CI = 1.042 ~ 2.024, P = 0.028) was positively correlated with the history of induced abortion.

CONCLUSIONS

The previous history of induced abortion is related to the outcomes of IVF /ICSI-ET, the endometrial thickness on HCG trigger day decreased, the risk of spontaneous abortion increased and the live birth rate decreased in patients with induced abortion history when undergoing IVF/ICSI-ET.

The Clinical Application of Platelet-Rich Plasma in the Female Reproductive System: A Narrative Review

Platelet-rich plasma is an autologous plasma containing platelets prepared from fresh whole blood drawn from a peripheral vein. Through processing, it can be prepared to contain supraphysiologic levels of platelets at three to five times greater than the level of normal plasma. PRP has been explored both in vivo and ex vivo in the human endometrium model in its ability to harness the intrinsic regenerative capacity of the endometrium. Intrauterine autologous PRP infusions have been shown to increase endometrial thickness and reduce the rate of intrauterine adhesions. In the setting of recurrent implantation failure, intrauterine infusion of PRP has been shown to increase clinical pregnancy rate. PRP also appears to hold a potential role in select patients with premature ovarian insufficiency, poor ovarian responders and in improving outcomes following frozen-thawed transplantation of autologous ovarian tissue. Further studies are required to explore the potential role of PRP in reproductive medicine further, to help standardise PRP protocols and evaluate which routes of administration are most effective.

Autologous Platelet-Rich Plasma (PRP) in Infertility-Infusion versus Injectable PRP

(1) Background: During IVF (in vitro fertilization) procedures, endometrial thickness has a significant role in the success of pregnancy outcomes for embryo transfers. Endometrial thickness, a crucial component of endometrial receptivity, is a contentious issue. The regenerative properties of PRP have been shown in recent research to have positive effects on the endometrium. PRP increases the pregnancy rate in IVF patients with thin endometrium and recurrent implantation failure. In order to demonstrate the efficacy of PRP therapies, this work compares the administration of injectable and infusible PRP during endometrial preparation. (2) Methods: This prospective single-arm control study was conducted at an IVF center in Oradea, Romania. This study included 50 patients; 27 were included in the group with Injectable PRP and 23 in the group with Infusible PRP. The outcome was compared between the two groups, with the primary outcome being the endometrial thickness after the PRP infusion or injection and the secondary outcome being the pregnancy rate in both groups. (3) Results: Patients who were treated with Injectable PRP had a higher pregnancy rate. An improvement in the quality of the endometrium, in terms of thickness, was also observed in the patients who were injected with PRP. (4) Conclusions: Compared to PRP infusions inside the uterus, sub-endometrial PRP injections in frozen embryo transfer methods have a greater pregnancy rate.

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.

Effect of endometrial thickness on obstetric and neonatal outcomes in assisted reproduction: a systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to explore the relationship of endometrial thickness (EMT) with obstetric and neonatal outcomes in assisted reproductive cycles.

METHODS

PubMed, EMBASE, Cochrane Library and Web of Science were searched for eligible studies through April 2023. Obstetric outcomes include placenta previa, placental abruption, hypertensive disorders of pregnancy (HDP), gestational diabetes mellitus (GDM) and cesarean section (CS). Neonatal outcomes include birthweight, low birth weight (LBW), gestational age (GA), preterm birth (PTB), small for gestational age (SGA) and large for gestational age (LGA). The effect size was estimated as odds ratio (OR) or mean difference (MD) with 95% confidence interval (CI) using a random-effects model. Inter-study heterogeneity was assessed by the chi-square homogeneity test. One-study removal method was used to determine the sensitivity of the meta-analysis.

RESULTS

Nineteen studies involving 76,404 cycles were included. The pooled results revealed significant differences between the thin endometrium group and the normal group in placental abruption (OR = 2.45, 95% CI: 1.11-5.38, P = 0.03; I² = 0%), HDP (OR = 1.72, 95% CI: 1.44-2.05, P < 0.0001; I² = 0%), CS (OR = 1.33, 95% CI: 1.06-1.67, P = 0.01; I² = 77%), GA (MD = -1.27 day, 95% CI: -2.41- -1.02, P = 0.03; I² = 73%), PTB (OR = 1.56, 95% CI: 1.34-1.81, P < 0.0001; I² = 33%), birthweight (MD = -78.88 g, 95% CI: -115.79- -41.98, P < 0.0001; I² = 48%), LBW (OR = 1.84, 95% CI: 1.52-2.22, P < 0.00001; I² = 3%) and SGA (OR = 1.41, 95% CI: 1.17-1.70, P = 0.0003; I² = 15%). No statistical differences were found in placenta previa, GDM, and LGA.

CONCLUSION

Thin endometrium was associated with lower birthweight or GA and higher risks of placental abruption, HDP, CS, PTB, LBW and SGA. Therefore, these pregnancies need special attention and close follow-up by obstetricians. Due to the limited number of included studies, further studies are needed to confirm the results.

The Therapeutic Potential of Multipotent Mesenchymal Stromal Cell-Derived Extracellular Vesicles in Endometrial Regeneration

Disruption of endometrial regeneration, fibrosis formation, and intrauterine adhesions underlie the development of "thin" endometrium and/or Asherman's syndrome (AS) and are a common cause of infertility and a high risk for adverse obstetric outcomes. The methods used (surgical adhesiolysis, anti-adhesive agents, and hormonal therapy) do not allow restoration of the regenerative properties of the endometrium. The experience gained today with cell therapy using multipotent mesenchymal stromal cells (MMSCs) proves their high regenerative and proliferative properties in tissue damage. Their contribution to regenerative processes is still poorly understood. One of these mechanisms is based on the paracrine effects of MMSCs associated with the stimulation of cells of the microenvironment by secreting extracellular vesicles (EVs) into the extracellular space. EVs, whose source is MMSCs, are able to stimulate progenitor cells and stem cells in damaged tissues and exert cytoprotective, antiapoptotic, and angiogenic effects. This review described the regulatory mechanisms of endometrial regeneration, pathological conditions associated with a decrease in endometrial regeneration, and it presented the available data from studies on the effect of MMSCs and their EVs on endometrial repair processes, and the involvement of EVs in human reproductive processes at the level of implantation and embryogenesis.

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.

Hypoxia-sensitive miRNA regulation via CRISPR/dCas9 loaded in hybrid exosomes: A novel strategy to improve embryo implantation and prevent placental insufficiency during pregnancy

Assisted reproductive techniques as a new regenerative medicine approach have significantly contributed to solving infertility problems that affect approximately 15% of couples worldwide. However, the success rate of an in vitro fertilization (IVF) cycle remains only about 20%-30%, and 75% of these losses are due to implantation failure (the crucial rate-limiting step of gestation). Implantation failure and abnormal placenta formation are mainly caused by defective adhesion, invasion, and angiogenesis. Placental insufficiency endangers both the mother's and the fetus's health. Therefore, we suggested a novel treatment strategy to improve endometrial receptivity and implantation success rate. In this strategy, regulating mir-30d expression as an upstream transcriptomic modifier of the embryo implantation results in modified expression of the involved genes in embryonic adhesion, invasion, and angiogenesis and consequently impedes implantation failure. For this purpose, "scaffold/matrix attachment regions (S/MARs)" are employed as non-viral episomal vectors, transfecting into trophoblasts by exosome-liposome hybrid carriers. These vectors comprise CRISPR/dCas9 with a guide RNA to exclusively induce miR-30d gene expression in hypoxic stress conditions. In order to avoid concerns about the fetus's genetic manipulation, our vector would be transfected specifically into the trophoblast layer of the blastocyst via binding to trophoblast Erb-B4 receptors without entering the inner cell mass. Additionally, S/MAR episomal vectors do not integrate with the original cell DNA. As an on/off regulatory switch, a hypoxia-sensitive promoter (HRE) is localized upstream of dCas9. The miR-30d expression increases before and during the implantation and placental insufficiency conditions and is extinguished after hypoxia elimination. This hypothesis emphasizes that improving the adhesion, invasion, and angiogenesis in the uterine microenvironment during pregnancy will result in increased implantation success and reduced placental insufficiency, as a new insight in translational medicine.

Efficacy of atosiban for repeated embryo implantation failure: A systematic review and meta-analysis

BACKGROUND

Repeated embryo implantation failure (RIF) posed a significant challenge in assisted reproduction. Evidence of its therapeutic effectiveness including atosiban used around embryo transfer to improve pregnancy outcomes in RIF patients undergoing in vitro fertilization-embryo transfer (IVF-ET) remained inconsistent. This study aimed to explore the efficacy of atosiban on pregnancy outcomes of patients with RIF who received IVF-ET.

METHODS

The research was designed using the PICOS format. A systematic search of four English databases, PubMed, EMBASE, Web of Science, Cochrane Library, and one Chinse database, China National Knowledge Infrastructure (CNKI) was conducted. The time range was from inception to December 10, 2022. Then trials comparing the efficacy of atosiban and control group on pregnancy outcomes in RIF patients who receive IVF-ET were included. Subgroup analysis and sensitivity analysis were performed to reduce the influence of heterogeneity between included studies. Risk ratio (RR) and 95% confidence interval (CI) were calculated. The main outcome measure was clinical pregnancy rate (CPR). For the analyses, StataMP 17.0 (Stata Corporation, USA) was used.

RESULTS

Two prospective randomized controlled trials (RCTs), one prospective cohort study and four retrospective cohort studies were included. Our results showed that atosiban was associated with higher clinical pregnancy rate (RR=1.54, 95% CI: 1.365-1.735, P < 0.001, I^{2 =} 0.0%). The results of subgroup analysis based on study types (prospective randomized controlled clinical trial, retrospective cohort study and prospective cohort study) showed that in all types of studies, CPR of atosiban group was significantly higher than controlled group. The results of subgroup analysis based upon the diagnostic criteria of number of previous embryo transfer failures showed that the intervention of atosiban improved the CPR whether in participants with 2 previous ET failures or in participants with 3 previous ET failures. Nevertheless, the incidence of ectopic pregnancy, multiple pregnancy, and miscarriages were not significantly different between the case and control groups.

CONCLUSION

For women who are undergoing IVF-ET and have experienced repeated embryo implantation failure, atosiban may be an important factor in enhancing pregnancy outcomes. To confirm this conclusion, more thorough, prospective randomized controlled studies of sizable sample sizes with well design are required.

Individual dynamics of uterine natural killer cells in natural and stimulated cycles monitored using a new endometrial dating method

PROBLEM

It is important to evaluate the dynamics of uterine natural killer (uNK) cells in hormone replacement therapy (HRT) cycles, given their potential role in implantation and the common usage of HRT cycles with in vitro fertilization (IVF).

METHOD OF STUDY

A total of 132 subfertile patients were evaluated during the secretory phase of either natural ovulation (OV) or HRT cycles, with two biopsies taken on approximately days 5 and 10 after ovulation/progesterone administration in a single menstrual cycle. Immunohistochemical Personal Endometrial Maturation Analysis (PEMA) was used to better quantify secretory-phase endometrial development, in combination with subsequent evaluation of uNK cell density.

RESULTS

uNK cell density increased rapidly from the early to mid-secretory phase, with mean uNK densities of 113 and 117 per mm² in first biopsies and 315 and 387 per mm² in second biopsies for OV and HRT cycles, respectively. After reassessment of endometrial development with PEMA, the first and second biopsies in HRT and OV cycles were histologically dated to developmental ranges between days 15-20 (first biopsy) and days 19-25 (second biopsy).

CONCLUSION

Subfertile women showed variable endometrial development in PEMA assessment, with uNK cell density correlating with the dating results. Overall, comparable levels of uNK cell density were observed in OV and HRT cycles. Importantly, uNK cell density depends on the histological maturation stage, with similar low coefficients of determination. This observation suggests that aberrant uNK cell results more likely reflect displaced endometrial maturation, rather than an intrinsic anomaly in uNK cell trafficking.

P16 and P21 are involved in the pathogenesis of endometrial thinning: A cross-sectional study

P16 plays a role in the negative regulation of cell proliferation, regulating cell apoptosis to control the growth of tumor cells. P21 is a nuclear protein that suppresses DNA synthesis and inhibits cell division. This study aimed to examine the expression and roles of P16 and P21 in endometrial thinning. Thirty cases of endometrial biopsy diagnosed as endometrial thinning were assessed by p16 and p21 immunohistochemistry from March 2014 to August 2020 in Huazhong University of Science and Technology Union Shenzhen Hospital. Another thirty cases of normal endometrium in the same period were assessed as controls. The specimens underwent histological analysis, and P16 and P21 were assessed by immunohistochemistry. There were no statistically significant differences in age, menstrual cycle, BMI, sex hormone levels, gravidity and parity between the two groups (all P > .05). In the endometrial thinning group, P16 was expressed in the endometrial adenoid nucleus, cytolymph and interstitial cell nucleus. In the normal group, P16 was mainly expressed in the endometrial adenoid nucleus, with some P16 signals detected in the endometrial interstitial nucleus. P21 expression was mainly detected in the endometrial adenoid nucleus. P16 and P21 amounts in endometrial thinning cases were significantly lower than those of the normal endometrial group. There was no correlation between p16 and p21 amounts. This study revealed aberrant expression of P16 and P21 in the endometrium might be due to a compensatory effect of the thin endometrium to increase cell proliferation and suppress cell apoptosis. However, the pathological roles of P16 and P21 in endometrial thinning and the contribution of cell senescence deserve further investigation.

Regenerative Effects of Locally or Intra-Arterially Administered BMSCs on the Thin Endometrium

Stem cell–based therapy plays a pivotal role in the regeneration of damaged endometrium. Previous studies have demonstrated the therapeutic potential of bone marrow mesenchymal stem cells (BMSCs) through diverse administration ways. However, the homing, survival, and differentiation potential of these differently administered BMSCs are poorly defined, and the best route of administration is not well-defined. Herein, we aim to compare the engraftment, retaining time, and therapeutic efficiency of differently administered BMSCs. To achieve this, GFP/Luc-labeled BMSCs administered in two modes were assessed in a thin endometrium rat model: either into the damaged horns directly or through the ipsilateral iliac artery. The retaining time and hemi-quantitative distribution were evaluated by in vivo bioluminescence imaging and immunohistological analysis. Locally administered BMSCs were strongly detected in the abdomen at the first 4 days post treatment but underwent a rapid decrease in luminescent signal afterward and were rarely found 28 days after treatment. In contrast, the retaining time of BMSCs injected through the iliac artery was longer, reflected by more GFP-positive cells detected in the uterine section 28 days post treatment. Differentiation toward endometrial stromal cells was observed. Both routes of administration contributed to the restoration of the damaged endometrium, showing a comparable increase in the endometrial thickness and a decrease in fibrosis. However, more importantly, higher expression of LIF and VEGF, better recruitment, and longer retainment were found in the intra-arterial administration, contributing to the establishment of the optimal administration mode in clinical practice.

Single-cell transcriptome analysis uncovers the molecular and cellular characteristics of thin endometrium

Infertility is a social and medical problem around the world and the incidence continues to rise. Thin endometrium (TE) is a great challenge of infertility treatment, even by in vitro fertilization and embryo transfer. It is widely believed that TE impairs endometrium receptivity. However, only a few studies have explained the molecular mechanism. Herein, in order to reveal the possible mechanism, we sampled endometrium from a TE patient and a control volunteer and got a transcriptomic atlas of 18 775 individual cells which was constructed using single-cell RNA sequencing, and seven cell types have been identified. The cells were acquired during proliferative and secretory phases, respectively. The proportion of epithelial cells and stromal cells showed a significant difference between the TE group and the control group. In addition, differential expressed genes (DEGs) in diverse cell types were revealed, the enriched pathways of DEGs were found closely related to the protein synthesis in TE of both proliferative and secretory phases. Some DEGs can influence cell-type ratio and impaired endometrial receptivity in TE. Furthermore, divergent expression of estrogen receptors 1 and progesterone receptors in stromal and epithelial cells were compared in the TE sample from the control. The cellular and molecular heterogeneity found in this study provided valuable information for disclosing the mechanisms of impaired receptivity in TE.

Xiaoyao powder improves endometrial receptivity via VEGFR-2-mediated angiogenesis through the activation of the JNK and P38 signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaoyao powder (XYP) is a traditional Chinese medicine formula which has wide scope of indications related to liver stagnation, reconcile qi and blood in TCM syndrome. Infertility can induce similar symptoms and signs to the clinical features of liver stagnation syndrome, the treatment of infertility by soothing the liver is obvious. XYP can increase the clinical pregnancy rate, follicle development, oocyte quality and improve endometrial receptivity. However, its underlying pharmacological mechanism of improving endometrial receptivity is unclear.

AIM OF THE STUDY

The aim of the study was to investigate the effect of XYP on pregnancy rates and endometrial angiogenesis, to determine the potent mechanism in association with the pro-angiogenic behavior which closely related to improving endometrial receptivity.

MATERIALS AND METHODS

We established an animal model exhibiting decreasing endometrial receptivity by controlled ovarian hyperstimulation and a human endometrial microvascular endothelial cell (HEMEC) model. Endometrial morphology was observed by hematoxylin-eosin staining and Scanning electron microscopy. Western blot and qRT-PCR analysis were used to detect expression of PCNA, Cyclin D1, MMP9 and MAPK signaling pathway. Scratch-wound assay and tube formation assay were used to observe HEMEC migration and tubulogenesis.

RESULTS

The results demonstrated that XYP pretreatment could improve endometrial receptivity, which leads to high pregnancy rates. In the endometrium, XYP facilitated angiogenesis by promoting tube formation. XYP could enhance HEMEC proliferation and migration induced by VEGF, which were observed by the microscope and Scratch-wound assays. XYP promoted HEMEC proliferation and migration via the p38 and JNK MAPK signaling pathways.

CONCLUSION

XYP promotes HEMEC proliferation and migration via the P38 and the JNK MAPK signaling pathways, which contribute to the endometrial angiogenesis mediated by VEGFR-2 that is favorable for endometrial receptivity. We firstly elucidated the molecular mechanisms by which XYP improved endometrial receptivity by promoting angiogenesis.

Growth Hormone: A Potential Treatment of Patients with Refractory Thin Endometrium: A Clinical Trial Study

BACKGROUND

Growth hormone (GH) is a potential treatment in the assisted reproductive technology (ART) to improve endometrial receptivity and thickness. In the current study, we investigated the effect of the intrauterine administration of GH on the endometrial thickness (EMT) and ART outcomes in the patients with refractory thin endometrium.

MATERIALS AND METHODS

In this clinical trial study, women with a refractory thin endometrium and a history of one or more frozen embryo transfer (FET) cancellation who were referred to the infertility center of the Tabriz Al-Zahra hospital (Tabriz, Iran) and Milad Infertility Clinic (Tabriz, Iran) received intrauterine injections of GH every other day from day 14 of the menstrual cycle until the EMT reached ≥7 mm in addition to the routine endometrium preparation protocol. EMT was evaluated during the treatment and in the cases with EMT ≥7 mm, biochemical/clinical pregnancy was evaluated after embryo transfer.

RESULTS

Thirty-one women aged 35.29 ± 6.21 years were included in this study. The mean amount of EMT was significantly increased following the GH treatment (7.03 ± 1.23 mm) vs. before treatment (5.14 ± 1.1 mm, P<0.001). The EMT reached ≥7 mm in the 65% patients (20/31). Also, the embryo transfer resulted in pregnancy in the patients, biochemical pregnancy: 9/20 (45%) and clinical pregnancy: 7/20 (35%). There was a positive correlation between EMT on the day 13 of cycle (before the treatment) and the maximum EMT (r=0.577 and P=0.001). The EMT was statistically different on the embryo transfer day between clinically pregnant and non-pregnant women (7.18 ± 0.56 vs. 6.21 ± 0.72 mm, P=0.007).

CONCLUSION

The intrauterine administration of GH could be an appropriate therapeutic strategy for patients with refractory thin endometrium. This treatment could significantly increase the EMT as well as implantation and pregnancy rates in these patients (registration number: IRCT20210220050429N1).

Effect of Intralipid infusion on peripheral blood T cells and plasma cytokines in women undergoing assisted reproduction treatment

Objectives

Intravenous infusion of Intralipid is an adjunct therapy in assisted reproduction treatment (ART) when immune‐associated infertility is suspected. Here, we evaluated the effect of Intralipid infusion on regulatory T cells (Treg cells), effector T cells and plasma cytokines in peripheral blood of women undertaking IVF.

Methods

This prospective, observational pilot study assessed Intralipid infusion in 14 women exhibiting recurrent implantation failure, a clinical sign of immune‐associated infertility. Peripheral blood was collected immediately prior to and 7 days after intravenous administration of Intralipid. Plasma cytokines were measured by Luminex, and T‐cell subsets were analysed by flow cytometry.

Results

A small increase in conventional CD8⁺ T cells occurred after Intralipid infusion, but no change was seen in CD4⁺ Treg cells, or naïve, memory or effector memory T cells. Proliferation marker Ki67, transcription factors Tbet and RORγt, and markers of suppressive capacity CTLA4 and HLA‐DR were unchanged. Dimensionality‐reduction analysis using the tSNE algorithm confirmed no phenotype shift within Treg cells or other T cells. Intralipid infusion increased plasma CCL2, CCL3, CXCL8, GM‐CSF, G‐CSF, IL‐6, IL‐21, TNF and VEGF.

Conclusion

Intralipid infusion elicited elevated pro‐inflammatory cytokines, and a minor increase in CD8⁺ T cells, but no change in pro‐tolerogenic Treg cells. Notwithstanding the limitation of no placebo control, the results do not support Intralipid as a candidate intervention to attenuate the Treg cell response in women undergoing ART. Future placebo‐controlled studies are needed to confirm the potential efficacy and clinical significance of Intralipid in attenuating cytokine induction and circulating CD8⁺ T cells.

Endometrial delay is found to be part of a normal individual dynamic transformation process

Purpose

Limited information is clinically available concerning endometrial receptivity; assessing endometrial transformation status is therefore an urgent topic in assisted reproductive technology. This study aimed to investigate individual endometrial transformation rates during the secretory phase in subfertile patients using personal endometrial transformation analysis.

Methods

Monitoring was carried out during the secretory phase to obtain endometrial receptivity profiles. For the investigation, two endometrial biopsies were taken within one menstrual cycle. The extended endometrial dating was based on the Noyes criteria, combined with immunohistochemical analyses of hormone receptors and proliferation marker Ki-67. Biopsies were taken mainly at days ovulation (OV, n = 76)/hormone replacement therapy (HRT, n = 58) + 5 and + 10.

Results

The results of the two biopsies were correlated with the clinically expected day of the cycle and showed temporal delays or hypercompensations, diverging from the expected cycle days by 0.5–5 days. In comparison with the first biopsies, the transformation rate in the second biopsies showed compensation, augmented delay, or constant transformation in 48.69, 22.37, and 28.94% of cases for ovulation in natural cycles and 56.89, 25.85, and 17.26% for HRT cycles, respectively.

Conclusion

The study revealed an individually dynamic transformation process of the endometrium, with the ability to compensate or enlarge an initial “delay”, which is now identified as a normal individual transformation process during the secretory phase. This information is of great importance for the scientific investigation of dynamic changes in endometrial tissue, as well as for the timing of embryo transfers.

Epithelial apical glycosylation changes associated with thin endometrium in women with infertility - a pilot observational study

BACKGROUND

Low endometrial receptivity is one of the major factors affecting successful implantation in assisted reproductive technologies (ART). Infertile patients with thin endometrium have a significantly lower cumulative clinical pregnancy rate than patients with normal endometrium. Molecular pathophysiology of low receptivity of thin endometrium remains understudied. We have investigated composition of glycocalyx of the apical surface of luminal and glandular epithelial cells in thin endometrium of infertile women.

METHODS

Thirty-two patients with tubal-peritoneal infertility undergoing in vitro fertilization (IVF) were included in the study. Endometrial samples were obtained in a natural menstrual cycle. Patients were divided into two groups: patients with normal endometrium (≥8 mm) and with thin endometrium (< 8 mm). Histochemical and immunohistochemical analysis of paraffin-embedded endometrial samples was performed using six biotinylated lectins (UEA-I, MAL-II, SNA, VVL, ECL, Con A) and anti-LeY and MECA-79 monoclonal antibodies (MAbs).

RESULTS

Complex glycans analysis taking into account the adjusted specificity of glycan-binding MAbs revealed 1.3 times less expression of MECA-79 glycans on the apical surface of the luminal epithelial cells of thin endometrium compared to normal endometrium; this deficiency may adversely affect implantation, since MECA-79 glycans are a ligand of L-selectin and mediate intercellular interactions. The glycans containing a type-2 unit Galβ1-4GlcNAcβ (LacNAc) but lacking sulfo-residues at 6-OH of GlcNAcβ, and binding to MECA-79 MAbs were found; they can be considered as potential markers of endometrium receptivity. Expression of the lectins-stained glycans on the apical surfaces of the luminal and glandular epithelial cells did not differ significantly. Correlation between the expression of difucosylated oligosaccharide LeY on the apical surfaces of the luminal and glandular epithelial cells was found in patients with thin endometrium and recurrent implantation failure. A similar relationship was shown for mannose-rich glycans.

CONCLUSIONS

Specific features of key glycans expression in epithelial compartments of thin endometrium may be essential for morphogenesis of the endometrial functional layer and explain its low receptivity.

The association between previous induced abortion and in vitro fertilization outcomes: A retrospective cohort study in Hefei, China

OBJECTIVES

To assess the association between previous induced abortion and in vitro fertilization (IVF) outcomes among Chinese women.

STUDY DESIGN

In this retrospective cohort study, a total of 1436 infertility patients treated with IVF for the first time in the reproductive centre of Anhui Province Maternity and Child Health Hospital from February 2014 to April 2018 were selected as the study population, and 95 (6.6 %) had a history of induced abortion. Data were assessed from the hospital electronic database and medical records in the reproductive centre.

RESULTS

In total, 818 women (57.0 %) achieved clinical pregnancy, and 501 (34.9 %) achieved live birth. After adjustments for a series of potential confounding factors, women with a history of induced abortion had a significantly decreased probability of clinical pregnancy per transfer (OR: 0.71, 95 % CI: 0.53, 0.95, p = 0.037) and live birth per pregnancy (OR: 0.52, 95 % CI: 0.30, 0.90, p = 0.021) and a higher risk of miscarriage per pregnancy (OR: 1.89, 95 % CI: 1.24, 2.88, p = 0.009) than those without. Because relevant information was unavailable, the impacts of different types of previous induced abortion were not assessed.

CONCLUSIONS

Previous induced abortion may have an adverse effect on IVF outcomes among infertility patients.

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.

Management of a Thin Endometrium by Hysteroscopic Instillation of Platelet-Rich Plasma Into The Endomyometrial Junction: A Pilot Study

In patients whose embryo transfer has been previously canceled due to a thin endometrium, the injection of platelet-rich plasma (PRP) guided by hysteroscopy into the endomyometrial junction improves endometrial thickness and vascularity. This may well serve as a novel approach for the management of these patients. In this study, 32 patients aged between 27 and 39 years, suffering from primary or secondary infertility, were selected for hysteroscopic instillation of PRP. This cross-sectional study included a retrospective assessment of the improvement of endometrial thickness (>7 mm) on the commencement of progesterone treatment in 24 of 32 patients (75%) after hysteroscopy-guided injections of PRP into the subendometrial zone. After PRP instillation, the endometrium was 7 mm or thicker in 24 of 32 patients, and all 24 patients underwent frozen embryo transfer. Moreover, 12 of 24 patients who underwent embryo transfer conceived, whereas 10 had a clinical pregnancy with visualization of cardiac activity at 6 weeks and two had a biochemical pregnancy. Our approach of PRP injection into the subendometrial region is consistent with the histologically proven regeneration of the endometrium from the endomyometrial junction. We observed an improvement of endometrial thickness and higher pregnancy rates in cases of previously canceled embryo transfer due to a thin endometrium.

FACTORS OF ENDOMETRIAL RECEPTIVITY DOWN-REGULATION IN GENITAL ENDOMETRIOSIS

Endometriosis, or endometrioid disease, is a chronic estrogen-dependent gynecological disease caused by ectopic localization of endometrial tissue, mainly in the pelvis and ovaries. However, at the present stage of development of reproductive medicine, the classical topographic definition of endometriosis should be expanded with new significant characteristics established using the achievements of cell and molecular biology, which allowed a more detailed study of the pathogenesis of this disease. In addition, the introduction of personalized approaches to the treatment of patients with endometriosis and infertility, more attention should be paid to the search for disease predictors and the formation of risk groups with the observation of patients from puberty to menopause. In this review, we have analyzed the literature data and our own studies with an emphasis on factors and markers of decreased receptivity of eutopic endometrium in women with endometriosis, as well as pain, the manifestations of which can contribute to the exact diagnosis of external genital endometriosis.

Thin endometrium problem in IVF programs

METHODS

Observational, comparative, prospective, multicenter study (n = 425). Group 1 (n = 228) received estradiol hemihydrate (Divigel, Orion Corporation, Finland), group 2 (n = 197) received oral estradiol valerate (Proginova, Delpharm Lille, France).

RESULTS

An increase in endometrial thickness was comparable (10.1 (2.0) mm versus 10.0 (2.3) mm; p = .571). There was significantly shorter mean duration of estrogen therapy (13.9 (3.9) days versus 14.7 (4.7) days; p = .038) and lower total dose in group 1 (43.6 (27.3) mg versus (71.9 (37.2) mg; p = .0001). Pregnancy rates were comparable (143/228 (62.7%) versus 105/197 (53.3%); p = .077) so as "take home baby" rates (80/228 (35.1%) versus 68/197 (34.5%); p = .077).

CONCLUSION

Estrogens improve the state of the endometrium and increase pregnancy rates in cases of thin endometrium in in vitro fertilization programs. The use of transdermal estrogens (Divigel, Orion Corporation, Finland) ensures an adequate increase in endometrial thickness and significantly lower estrogen doses.

Correlation between endometrial thickness and perinatal outcome for pregnancies achieved through assisted reproduction technology

Objective To explore the relationship between endometrial thickness and perinatal outcome in assisted reproductive techniques (ART). Methods A retrospective cohort study was conducted in 1139 infertile women who underwent ART treatment from January 2011 to July 2014. Four groups were divided by endometrial thickness on the human chorionic gonadotropin (HCG) trigger day in fresh embryo transfer cycles or on the progesterone administration day in frozen embryo transfer cycles, as group A (<8 mm), group B (8-10 mm), group C (10-14 mm) and group D (≥14 mm). Two other groups were delineated according to whether uterine lesions were present. The incidence of premature rupture of membranes (PROM), postpartum hemorrhage (PPH) and other common perinatal complications were observed subsequently. Results It was found that the highest incidence of PROM and PPH was in group A (P < 0.05). The incidence of PROM in group B was higher than in groups C and D (P < 0.05). The occurrence of mothers entering the intensive care unit (ICU) was significantly higher in group A than in group B (P < 0.05). However, no significant differences were found in other adverse outcomes. There was no difference in the incidence of adverse perinatal outcome when the endometrial thickness of pre-implantation was not attenuated by uterine lesions. Conclusion The incidence of PROM and PPH increased significantly when the thickness of the endometrium was less than 10 mm before implantation. Correspondingly, the number of mothers treated in the ICU was also higher under these circumstances. To reduce such perinatal placenta-related complications, we should maximize the thickness of the endometrium before transplantation of embryos.

Endometrial Flushing Tumor Necrosis Factor Alpha and Interleukin 2 Levels in Women with Polycystic Ovary Syndrome, Leiomyoma and Endometrioma: Comparison with Healthy Controls

Introduction An important open question in the literature is whether endometrial receptivity marker levels are different in infertility related diseases than healthy women. The aim of the study is to compare the levels of interleukin two (IL-2) and tumor necrosis factor alpha (TNF-α) during the implantation window in the endometrial flushing fluid of polycystic ovary syndrome (PCOS), endometrioma, leiomyoma patients with healthy controls. Material and Methods In this case control study, after obtaining endometrial flushing fluids at mid-luteal phase of ovulatory women with PCOS (n = 20), endometrioma (n = 19), leiomyoma (n = 20) and healthy controls (n = 20), IL-2 and TNF-α levels were measured using ELISA kits in BioTek ELISA devices. Results Mean TNF-α levels (ng/mL) were similar for the PCOS (305.6, p = 0.220) and the leiomyoma group (246.3, p = 0.502) compared to healthy patients (261.1). However, the levels were higher in the endometrioma group (338.2, p = 0,004) than the control group (261.1) in a statistically significant way. Mean IL-2 levels (ng/mL) were significantly lower in the PCOS (290.9, p = 0.0005), the leiomyoma (282.9, p = 0.0002) and the endometrioma patients (229.5, p = 0.0009) than the control group (416.0). Conclusion Relative to the control group, endometrial flushing fluid TNF-α levels were significantly higher in endometrioma patients and IL-2 levels were significantly lower in PCOS, leiomyoma and endometrioma patients. In benign gynecological diseases, endometrial markers related to infertility seem to show differences in endometrial flushing fluid. Future studies might identify the reference values for these markers, and endometrial markers can be used to diagnose gynecologic disorders causing infertility.

Effects of pelvic floor bioelectrical stimulation on frozen embryo transfer patients with thin endometrium

This study was to observe the effects of pelvic floor bioelectrical stimulation on pregnancy outcome and serum estradiol (E2) and progesterone (P) levels in frozen embryo transfer patients with thin endometrium. 120 cases frozen embryo transfer patients with thin endometrium in our hospital from March 2016 to April 2017 were selected. These patients received artificial cycle replacement plan before embryo transfer. According to whether pelvic floor bioelectrical stimulation therapy was accepted, 120 cases of thin endometrial frozen embryo transfer were divided into control group and observation group. 50 cases of the control group received artificial cycle to prepare for embryo transplantation, while 70 cases of observation group received bioelectrical stimulation as intervention treatment on the basis of artificial cycle. The intima thickness, subintimal hemodynamic parameters, embryo implantation rate, and clinical pregnancy rate were compared between the two groups before and after treatment. There was no significant difference in endometrial thickness between the two groups on the 10th day of menstruation ( P > 0.05). The thickness of endometrium and the index of intima growth in the observation group were significantly higher than those in the control group ( P < 0.05). The pulsatility index, resistance index, and systolic and diastolic blood flow velocity ratio of subintimal blood flow in the observation group were significantly higher than those in the control group ( P < 0.05). Before treatment, there was no significant difference in serum E2 and P between the two groups ( P > 0.05). After treatment, the improvement of serum E2 and P in the observation group was significantly better than that of the control group ( P < 0.05). The embryo implantation rate (25.7%) in the observation group was significantly higher than that in the control group (17.0%) ( P < 0.05). The clinical pregnancy rate (47.1%) in the observation group was significantly higher than that in the control group (30%) ( P < 0.05). In conclusion, the intervention of pelvic floor bioelectrical stimulation can improve the blood perfusion of thin endometrium, improve the endometrial receptivity, increase the implantation rate of frozen embryo transfer in patients with thin endometrium, and improve the level of serum estradiol and progesterone.