Therapeutic role of granulocyte macrophage colony-stimulating factor (GM-CSF) in patients with persistent thin endometrium: A prospective and randomized study

Network meta-analysis of four common immunomodulatory therapies for the treatment of patients with thin endometrium

OBEJECTIVE

To compare the effectiveness of endometrial receptivity and pregnancy outcomes of four common immunomodulatory therapies for patients with thin endometrium.

METHOD

This systematic review and network meta-analysis using a literature search up to January 2024, to identify relevant trials comparing endometrial receptivity and pregnancy outcomes of human chorionic gonadotropin (hCG), platelet-rich plasma (PRP), infusion of granulocyte colony-stimulating factor (IG-CSF), and peripheral blood mononuclear cell (PBMC) for patients with thin endometrium. We used surface under the cumulative ranking (SUCRA) to ranked four common immunomodulatory therapies on endometrium thickness, implantation rate (IR), clinical pregnancy rate (CPR), and live birth rate (LBR). RoB2 and ROBINS-I were used to assess the certainty of evidence.

RESULTS

The pooled results of 22 studies showed that hCG (mean difference [MD]: 3.05, 95% confidence interval [CI]: 1.46-4.64) and PRP (MD: 0.98, 95% CI: 0.20-1.76) significantly increase endometrium thickness. The hCG was the best among the IG-CSF (MD = -2.56, 95% CI = -4.30 to -0.82), PBMC (MD = -2.75, 95% CI = -5.49 to -0.01), and PRP (MD = -2.07, 95% CI = -3.84 to -0.30) in increasing endometrium thickness. However, IG-CSF and PRP significantly improved IR (IG-CSF: risk ratio (RR; IG-CSF: RR = 1.33, 95% CI = 1.06-1.67; PRP: RR = 1.63, 95% CI = 1.19-2.23), and LBR (IG-CSF: RR = 1.53, 95% CI = 1.16-2.02; PRP: RR = 1.59, 95% CI = 1.08-2.36).

CONCLUSIONS

Available evidence reveals that hCG and subcutaneous or intrauterine CSF (SG-CSF) may be the best treatment options for current thin endometrium patients. However, future high-quality and large-scale studies are necessary to validate our findings.

Injectable, stable, and biodegradable hydrogel with platelet-rich plasma induced by l-serine and sodium alginate for effective treatment of intrauterine adhesions

The combination of pharmacological and physical barrier therapy is a highly promising strategy for treating intrauterine adhesions (IUAs), but there lacks a suitable scaffold that integrates good injectability, proper mechanical stability and degradability, excellent biocompatibility, and non-toxic, non-rejection therapeutic agents. To address this, a novel injectable, degradable hydrogel composed of poly(ethylene glycol) diacrylate (PEGDA), sodium alginate (SA), and l-serine, and loaded with platelet-rich plasma (PRP) (referred to as PSL-PRP) is developed for treating IUAs. l-Serine induces rapid gelation within 1 min and enhances the mechanical properties of the hydrogel, while degradable SA provides the hydrogel with strength, toughness, and appropriate degradation capabilities. As a result, the hydrogel exhibits an excellent scaffold for sustained release of growth factors in PRP and serves as an effective physical barrier. In vivo testing using a rat model of IUAs demonstrates that in situ injection of the PSL-PRP hydrogel significantly reduces fibrosis and promotes endometrial regeneration, ultimately leading to fertility restoration. The combined advantages make the PSL-PRP hydrogel very promising in IUAs therapy and in preventing adhesions in other internal tissue wounds.

GM-CSF improves endometrial receptivity in a thin endometrium rat model by upregulating HOXA10

Endometrial receptivity is a prerequisite for the success of assisted reproduction. Patients with a consistently thin endometrium frequently fail to conceive, owing to low endometrial receptivity, and there are currently very few therapeutic options available. Our previous study demonstrated that intrauterine granulocyte-macrophage colony-stimulating factor (GM-CSF) administration resulted in a significant improvement in clinical pregnancy and implantation rates and was an effective means of increasing endometrial thickness on the day of embryo transfer in patients with thin endometrium. In order to explore the underlying process, an animal model with a thin endometrium was constructed, the homeobox A10 gene (HOXA10) was downregulated, and an inhibitor of the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway (MAPK/ERK) was employed. Our findings strongly suggest a marked decrease in GM-CSF levels in the thin endometrial rat model, and the suppression of HOXA10 impeded the therapeutic efficacy of GM-CSF in this model. Moreover, we showed that GM-CSF significantly increases endometrial receptivity in the rat model and upregulates HOXA10 via the MAPK/ERK pathway. Our data provide new molecular insights into the mechanisms underlying formation of a thin endometrium and highlight a novel, potential clinical treatment strategy as well as directions for further research.

Granulocyte-macrophage colony-stimulating factor promotes endometrial repair after injury by regulating macrophages in mice

Intrauterine adhesion (IUA) caused by endometrial injury is a common cause of female infertility and is challenging to treat. Macrophages play a critical role in tissue repair and cyclical endometrial regeneration. Granulocyte-macrophage colony-stimulating factor (GM-CSF) has significant reparative and anti-fibrotic effects in various tissues. However, there is limited research on the role of GM-CSF in the repair of endometrial injury and the involvement of macrophages in GM-CSF-mediated endometrial repair. In this study, using a mouse model of endometrial scratching injury, we found that GM-CSF treatment accelerated the repair of endometrial injury and improved fertility. At the molecular level, we observed that GM-CSF can downregulate the transcript levels of tumor necrosis factor (TNF) in mouse bone marrow-derived macrophages (BMDMs) stimulated by lipopolysaccharide (LPS) and upregulate the expression of Arginase-1 (Arg-1) and mannose receptor C-type 1 (MRC1). Importantly, during the early and middle stages of injury, GM-CSF increased the proportion of M1-like, M2-like, and M1/M2 mixed macrophages, while in the late stage of injury, GM-CSF facilitated a decline in the number of M2-like macrophages. These findings suggest that GM-CSF may promote endometrial repair by recruiting macrophages and modulating the LPS-induced M1-like macrophages into a less inflammatory phenotype. These insights have the potential to contribute to the development of novel therapeutic approaches for the treatment of intrauterine adhesion and related infertility.

A critical appraisal of studies on endometrial thickness and embryo transfer outcome

A receptive endometrium is required for successful embryo implantation. Endometrial thickness, as measured by ultrasonography, is the most commonly used marker of endometrial receptivity in assisted reproductive technology cycles. Several factors simultaneously affect both endometrial thickness and probability of live birth, including age, oestradiol concentration and oocyte number, among others. Most of the studies investigating a relationship between endometrial thickness and embryo transfer outcomes are retrospective and do not adequately address confounding factors, in addition to other limitations. Despite multiple meta-analyses and studies with large numbers of cycles, controversy still exists. The difference between the results from prospective and retrospective studies is also striking. This article presents a critical appraisal of the studies on endometrial thickness and embryo transfer outcomes in order to highlight methodological issues and how they can be overcome in future studies. Currently available evidence does not seem to support a modification of management just because endometrial thickness is below an arbitrary threshold.

Recent progress of Bioinspired Hydrogel-based delivery system for endometrial repair

Endometrial injury is the main fact leading to infertility. Current treatments of endometrial injury present many problems, such as unable to achieve desired effects due to low retention and the inherent potential risk of injury. Besides, it is important to the development of bioinspired material that can mimic the natural tissue and possess native tissue topography. Hydrogel is a kind of bioinspired superhydrophilic materials with unique characteristics, such as excellent biocompatibility, biodegradability, porosity, swelling, and cross-linkage. These unique physiochemical properties of bioinspired hydrogels enable their promising application as novel delivery platform and alternative therapies for endometrial injury. In this mini review, we summarize the recent advances in bioinispred hydrogel-based delivery system for endometrial repair, including as a post-operative physical barrier and therapeutic delivery system. In addition, present status, limitations, and future perspectives are also discussed.

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.

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.

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.

Understanding the Impact of Uterine Fibroids on Human Endometrium Function

Uterine fibroids (leiomyomas) are the most common benign gynecological tumors in women of reproductive age worldwide. They cause heavy menstrual bleeding, usually leading to severe anemia, pelvic pain/pressure, infertility, and other debilitating morbidities. Fibroids are believed to be monoclonal tumors arising from the myometrium, and recent studies have demonstrated that fibroids actively influence the endometrium globally. Studies suggest a direct relationship between the number of fibroids removed and fertility problems. In this review, our objective was to provide a complete overview of the origin of uterine fibroids and the molecular pathways and processes implicated in their development and growth, which can directly affect the function of a healthy endometrium. One of the most common characteristics of fibroids is the excessive production of extracellular matrix (ECM) components, which contributes to the stiffness and expansion of fibroids. ECM may serve as a reservoir of profibrotic growth factors such as the transforming growth factor β (TGF-β) and a modulator of their availability and actions. Fibroids also elicit mechanotransduction changes that result in decreased uterine wall contractility and increased myometrium rigidity, which affect normal biological uterine functions such as menstrual bleeding, receptivity, and implantation. Changes in the microRNA (miRNA) expression in fibroids and myometrial cells appear to modulate the TGF-β pathways and the expression of regulators of ECM production. Taken together, these findings demonstrate an interaction among the ECM components, TGF-β family signaling, miRNAs, and the endometrial vascular system. Targeting these components will be fundamental to developing novel pharmacotherapies that not only treat uterine fibroids but also restore normal endometrial function.

Hysteroscopy and female infertility: a fresh look to a busy corner

Hysteroscopy has evolved from the traditional art of examining the uterine cavity for diagnostic purposes to an invaluable modality to concomitantly diagnose and (see and) treat a multitude of intrauterine pathologies, especially in the field and clinics specialising in female reproduction. This article reviews the literature on the most common cervical, endometrial, uterine and tubal pathologies such as chronic endometritis, endometrial polyps, adenomyosis, endometriosis, endometrial atrophy, adhesions, endometrial hyperplasia, cancer, and uterine malformations. The aim is to determine the efficiency of hysteroscopy compared with other available techniques as a diagnostic and treatment tool and its association with the success of in vitro fertilisation procedures. Although hysteroscopy requires an experienced operator for optimal results and is still an invasive procedure, it has the unique advantage of combining great diagnostic and treatment opportunities before and after ART procedures. In conclusion, hysteroscopy should be recommended as a first-line procedure in all cases with female infertility, and a special effort should be made for its implementation in the development of new high-tech procedures for identification and treatment infertility-associated conditions.

Application of Hydrogel-Based Delivery System in Endometrial Repair

A receptive endometrium with proper thickness is essential for successful embryo implantation. However, endometrial injury caused by intrauterine procedures often leads to pathophysiological changes in its environment, resulting in subsequent female infertility. Among diverse treatment methods of endometrial injury, hydrogels are a class of hydrophilic three-dimensional polymeric network with biocompatibility as well as the capability of absorbing water and encapsulation, which have potential applications as a promising intrauterine controlled-release delivery system. This review summarizes recent advances in the approaches of endometrial repair and further focuses on the application of a hydrogel-based delivery system in endometrial repair, including its preparation, therapeutic loading considerations, clinical applications, as well as working mechanisms.