SFRP4+ stromal cell subpopulation with IGF1 signaling in human endometrial regeneration

Natural regeneration-inspired sequential delivery of synergistic growth factors for structural and functional endometrial regeneration

Large-scale deep endometrial injury has a serious impact on the reproductive health of women, necessitating the development of novel therapeutic approaches. Treatment strategies using single factor may not perfectly match the intricate and dynamic process of endometrial regeneration. In light of the sequential progression of vascularization and endometrial remodeling observed during the regeneration of injured endometrium, a dual growth factor sequential delivery system is prepared by loading IGF-1 onto hydrogel microspheres and blending with an outer bulk hydrogel containing VEGF. The controlled degradation of hydrogel facilitates the sequential release of the two factors, thereby fostering the vascularization, migration and proliferation of endometrial cells in vitro. Animal experiments have proved that the hydrogel system can promote the regeneration of endometrial structure through vascular remodeling, glandular regeneration, and proliferation of endometrial cells, and simultaneously improve the rate of embryo implantation and live birth, which further indicates the functional reconstruction of the injured endometrium. Consequently, drawing inspiration from the sequential process of endometrial regeneration, this study provides innovative strategies for structural and functional restoration of the endometrium. STATEMENT OF SIGNIFICANCE: This research presents an innovative approach to the treatment of injured endometrium through a sequential dual growth factor delivery system. The system involves the incorporation of IGF-1 onto hydrogel microspheres, which are subsequently embedded within a GelMA hydrogel matrix containing VEGF. Unlike conventional hydrogel-based therapeutic strategies that involve the loading of growth factors, the developed delivery system is engineered in accordance with the vascularization and endometrial remodeling processes inherent to the regeneration of injured endometrial tissue. It facilitates the initial release of VEGF to stimulate the formation of blood vessels, followed by a gradual release of IGF-1 during the intermediate phase of endometrial regeneration to promote tissue remodeling. Pre-clinical animal studies have demonstrated that this innovative delivery strategy effectively restores the structure and function of the endometrium, suggesting significant potential for clinical application.

Significance of Midkine Signaling in Women's Cancers: Novel Biomarker and Therapeutic Target

Midkine (MDK) is a multifunctional protein that is secreted into the extracellular space. It functions as a cytokine or growth factor, modulating a variety of signaling pathways implicated in angiogenesis, antitumor immunity, metastasis, and therapy resistance. MDK overexpression has been documented in a variety of cancers, including those that affect women. MDK mediates its effects through activation of key signaling pathways such as MAPK/ERK, PI3K/AKT, and STAT3, which are pivotal for cell cycle progression, survival, and maintenance of stemness. Obesity and estrogen signaling, a known critical driver of women's cancer, further elevate the levels of MDK. MDK's effects are mediated by a variety of membrane receptors, such as integrins, protein tyrosine phosphatase ζ (PTPζ), anaplastic lymphoma kinase (ALK), and neurogenic locus notch homolog protein 2 (Notch2). Recently published studies have indicated that MDK is a potential therapeutic target and a biomarker for the progression of women's cancer. In this review, we have provided a concise summary of the most recent papers that have examined the potential biomarker and therapeutic utility of MDK signaling in women's cancer.

Single-cell transcriptome profiling of the human endometrium of patients with intrauterine adhesions

Intrauterine adhesions (IUAs) are a complex condition that frequently results in menstrual disturbances, infertility, and obstetric complications. Unfortunately, the underlying pathophysiology of IUAs remains poorly understood, and current treatments often exhibit limited efficacy. We performed the single-cell RNA-sequencing (scRNA-Seq) comparison of 5 endometrial tissues, including patients with confirmed intrauterine adhesions and healthy controls(HCs). We profiled the transcriptomes of 55,308 primary human endometrial cells isolated from healthy controls and intrauterine adhesions patients at single-cell resolution. Compared with those in HCs, the number of fibroblasts derived from IUAs significantly decreased. Further analysis found that fibroblasts subcluster 3 were enriched in the IUAs, whereas opposite in HCs. GO enrichment analysis revealed that specific genes of fibroblasts subcluster 3 were markedly involved in the positive regulation of embryonic placenta development, the response to reactive oxygen species and female pregnancy, and the positive regulation of the mitotic DNA damage checkpoint and DNA damage response. In addition, the proportion of proliferating endothelial cells was significantly lower in IUAs. GO enrichment analysis revealed that the specific genes were markedly involved in the positive regulation of cell cycle arrest, the cellular response to interferon - gamma and the negative regulation of the mitotic cell cycle. According to the number of intercellular receptor-ligand pairs, we identified endothelial cells as the core cell population. Our study provides deeper insights into the endometrial microenvironment disorders that are potentially applicable to improving therapeutics for IUAs.

Asherman syndrome at single-cell resolution

This comprehensive review aimed to provide insights into the Asherman syndrome's historical background, clinical manifestations, classifications, obstetrical challenges, and current treatment approaches. The syndrome is characterized by intrauterine adhesions and fibrotic changes within the uterine tract as well as symptoms including menstrual irregularities, pelvic pain and infertility. The primary causes of Asherman syndrome are often associated with iatrogenic complications and congenital uterine defects. The syndrome results in certain obstetrical challenges, including recurrent pregnancy loss, placenta abnormalities, preterm birth, and intrauterine growth retardation, emphasizing the need for effective management. Hysteroscopic adhesiolysis represents the current gold standard treatment, but challenges persist because of adhesion recurrence and obstetrical complications. In this sense, emerging therapies were explored, including paracrine-acting factors, tissue-engineered scaffolds, and cell-based therapies. Autologous CD133+ bone marrow-derived stem cell therapy shows promise, with clinical trials demonstrating improved endometrial conditions and positive obstetrical outcomes. The review concludes by highlighting the potential of single-cell RNA sequencing to unravel the molecular mechanisms behind Asherman syndrome. This advanced technology offers insights into the gene expression profiles of individual cells, fostering a deeper understanding of Asherman syndrome pathogenesis and the development of innovative therapeutic strategies.

Enhanced myofibroblast differentiation of eMSCs in intrauterine adhesions

BACKGROUND

Intrauterine adhesions (IUA) is one of the most common gynecological diseases and main causes of uterine infertility. Among proposed hypotheses on IUA development, the reduced endometrial regeneration resulting from loss of functional stem cells has been proposed as the key factor affecting the IUA prognosis. However, the underlying mechanisms mostly remain unclear. Because the eMSCs (endometrial mesenchymal stem/stromal cells) play a critical role in both supporting the gland development and also preparing the environment for embryo implantation through decidualization, the characteristics and functions were compared between the eMSCs derived from IUA and non-IUA patients, to uncover the important roles of eMSCs in IUA and also the underlying mechanisms.

METHODS

Endometrium biopsies were collected from IUA patients and controls. The fibrosis features and eMSC distributions were investigated with IHC (immunohistochemistry). Then the eMSCs were isolated and their functions and characteristics were analyzed in vitro.

RESULTS

Our results indicate that the scar tissues in IUA are characterized with hyper-activation of pro-fibrotic fibroblast and myo-differentiation, along with reduced number of eMSCs. The isolated eMSCs from IUA and controls show similar functions from the perspectives of cell morphology, proliferation, colony formation, exosome secretion, positive ratio of eMSC markers and conventional MSC markers, tri-differentiation efficiency, the ability of suppressing lymphocyte proliferation, cell aging, and promoting vascular tube formation. However, the eMSCs from IUA have reduced levels of decidualization and higher levels of cell migration, invasion, and also myofibroblast differentiation. Further investigations indicate that the TGF-β pathway, which is the major inducer of myofibroblast differentiation, is up-regulated and responsible for the enhanced myofibroblast differentiation potential of eMSCs from IUA.

CONCLUSIONS

In conclusion, we have demonstrated here that the scar tissues in IUA biopsy are characterized with enhanced differentiation of pro-fibrotic fibroblast and myofibroblast. The number of eMSCs is reduced in IUA tissues, and their myofibroblast differentiation capability is increased.

Multi-omics-based mapping of decidualization resistance in patients with a history of severe preeclampsia

Endometrial decidualization resistance (DR) is implicated in various gynecological and obstetric conditions. Here, using a multi-omic strategy, we unraveled the cellular and molecular characteristics of DR in patients who have suffered severe preeclampsia (sPE). Morphological analysis unveiled significant glandular anatomical abnormalities, confirmed histologically and quantified by the digitization of hematoxylin and eosin-stained tissue sections. Single-cell RNA sequencing (scRNA-seq) of endometrial samples from patients with sPE (n = 11) and controls (n = 12) revealed sPE-associated shifts in cell composition, manifesting as a stromal mosaic state characterized by proliferative stromal cells (MMP11 and SFRP4) alongside IGFBP1+ decidualized cells, with concurrent epithelial mosaicism and a dearth of epithelial-stromal transition associated with decidualization. Cell-cell communication network mapping underscored aberrant crosstalk among specific cell types, implicating crucial pathways such as endoglin, WNT and SPP1. Spatial transcriptomics in a replication cohort validated DR-associated features. Laser capture microdissection/mass spectrometry in a second replication cohort corroborated several scRNA-seq findings, notably the absence of stromal to epithelial transition at a pathway level, indicating a disrupted response to steroid hormones, particularly estrogens. These insights shed light on potential molecular mechanisms underpinning DR pathogenesis in the context of sPE.

Surface Molecular Markers for the Isolation of Viable Fibroblast Subpopulations in the Female Reproductive Tract: A Comprehensive Review

Advancements in single-cell analyzis technologies, particularly single-cell RNA sequencing (scRNA-seq) and Fluorescence-Activated Cell Sorting (FACS), have enabled the analyzis of cellular diversity by providing resolutions that were not available previously. These methods enable the simultaneous analyzis of thousands of individual transcriptomes, facilitating the classification of cells into distinct subpopulations, based on transcriptomic differences, adding a new level of complexity to biomolecular and medical research. Fibroblasts, despite being one of the most abundant cell types in the human body and forming the structural backbone of tissues and organs, remained poorly characterized for a long time. This is largely due to the high morphological similarity between different types of fibroblasts and the lack of specific markers to identify distinct subpopulations. Once thought to be cells responsible solely for the synthesis of extracellular matrix (ECM) components, fibroblasts are now recognized as active participants in diverse physiological processes, including inflammation and antimicrobial responses. However, defining the molecular profile of fibroblast subpopulations remains a significant challenge. In this comprehensive review, which is based on over two thousand research articles, we focus on the identification and characterization of fibroblast subpopulations and their specific surface markers, with an emphasis on their potential as molecular targets for selective cell isolation. By analyzing surface markers, alongside intra- and extracellular protein profiles, we identified multiple fibroblast subtypes within the female reproductive system. These subtypes exhibit distinct molecular signatures and functional attributes, shaped by their anatomical localization and the surrounding physiological or pathological conditions. Our findings underscore the heterogeneity of fibroblasts and their diverse roles in various biological contexts. This improved understanding of fibroblast subpopulations paves the way for innovative diagnostic and therapeutic strategies, offering the potential for precision targeting of specific fibroblast subsets in clinical applications.

Varied cellular abnormalities in thin vs. normal endometrium in recurrent implantation failure by single-cell transcriptomics

BACKGROUND

Reduced endometrium thickness and receptivity are two important reasons for recurrent implantation failure (RIF). In order to elucidate differences between these two types of endometrial defects in terms of molecular signatures, cellular interactions, and structural changes, we systematically investigated the single-cell transcriptomic atlas across three distinct groups: RIF patients with thin endometrium (≤ 6 mm, TE-RIF), RIF patients with normal endometrium thickness (≥ 8 mm, NE-RIF), and fertile individuals (Control).

METHODS

The late proliferative and mid-secretory phases of the endometrium were collected from three individuals in the TE-RIF group, two in the NE-RIF group, and three in the control group. The study employed a combination of advanced techniques. Single-cell RNA sequencing (scRNA-seq) was utilized to capture comprehensive transcriptomic profiles at the single-cell level, providing insights into gene expression patterns within specific cell types. Scanning and transmission electron microscopy were employed to visualize ultrastructural details of the endometrial tissue, while hematoxylin and eosin staining facilitated the examination of tissue morphology and cellular composition. Immunohistochemistry techniques were also applied to detect and localize specific protein markers relevant to endometrial receptivity and function.

RESULTS

Through comparative analysis of differentially expressed genes among these groups and KEGG pathway analysis, the TE-RIF group exhibited notable dysregulations in the TNF and MAPK signaling pathways, which are pivotal in stromal cell growth and endometrial receptivity. Conversely, in the NE-RIF group, disturbances in energy metabolism emerged as a primary contributor to reduced endometrial receptivity. Additionally, using CellPhoneDB for intercellular communication analysis revealed aberrant interactions between epithelial and stromal cells, impacting endometrial receptivity specifically in the TE-RIF group.

CONCLUSION

Overall, our findings provide valuable insights into the heterogeneous molecular pathways and cellular interactions associated with RIF in different endometrial conditions. These insights may pave the way for targeted therapeutic interventions aimed at improving endometrial receptivity and enhancing reproductive outcomes in patients undergoing ART. Further research is warranted to validate these findings and translate them into clinical applications for personalized fertility treatments.

TRIAL REGISTRATION

Not applicable.

Unraveling the Dynamics of Estrogen and Progesterone Signaling in the Endometrium: An Overview

The endometrium is crucial for the perpetuation of human species. It is a complex and dynamic tissue lining the inner wall of the uterus, regulated throughout a woman's life based on estrogen and progesterone fluctuations. During each menstrual cycle, this multicellular tissue undergoes cyclical changes, including regeneration, differentiation in order to allow egg implantation and embryo development, or shedding of the functional layer in the absence of pregnancy. The biology of the endometrium relies on paracrine interactions between epithelial and stromal cells involving complex signaling pathways that are modulated by the variations of estrogen and progesterone levels across the menstrual cycle. Understanding the complexity of estrogen and progesterone receptor signaling will help elucidate the mechanisms underlying normal reproductive physiology and provide fundamental knowledge contributing to a better understanding of the consequences of hormonal imbalances on gynecological conditions and tumorigenesis. In this narrative review, we delve into the physiology of the endometrium, encompassing the complex signaling pathways of estrogen and progesterone.

Restoration of functional endometrium in an intrauterine adhesion rat model with endometrial stromal cells transplantation

BACKGROUND

Intrauterine adhesion (IUA) as a prevalent gynecological disease is developed from infection or trauma. However, therapeutic strategies to repair damaged endometrium are relatively limited. Emerging studies have shed light on the crucial role of endometrial stromal cells (EnSCs) in the process of uterine endometrial regeneration. EnSCs isolated from the uterine endometrium have similar characteristics to mesenchymal stem cells (MSCs). However, it is still unknown whether EnSCs could be used as donor cells to treat IUA. The aim of this study was to evaluate the potential efficacy of EnSCs in treating rat IUA.

METHODS

Human EnSCs were isolated from the endometrial tissue of healthy female donors and subjected to extensive expansion and culture in vitro. Immunofluorescence, flow cytometry, cell proliferation assay, trilineage differentiation experiment, and decidualization assay were used to characterize the biological properties of EnSCs. We evaluated the immunoregulatory potential of EnSCs by analyzing their secreted cytokines and conducting bulk RNA sequencing after IFN-γ treatment. After EnSCs were transplanted into the uterine muscle layer in IUA rats, their therapeutic effects and underlying mechanisms were analyzed using histological analysis, Q-PCR, fertility and pregnancy outcome assay, and transcriptome analysis.

RESULTS

We successfully isolated EnSCs from the endometrium of human donors and largely expanded in vitro. EnSCs exhibited characteristics of mesenchymal stem cells and retained responsiveness to sex hormones. Following IFN-γ stimulation, EnSCs upregulated the anti-inflammatory cytokines and activated immunosuppressive molecules. Xenogeneic transplantation of EnSCs successfully repaired injured endometrium and significantly restored the pregnancy rate in IUA rats. Mechanistically, the therapeutic effects of EnSCs on IUA endometrium functioned through anti-inflammation, anti-fibrosis and the secretion of regeneration factor.

CONCLUSIONS

Due to their large expansion ability, immunoregulatory properties, and great potential in treating IUA, EnSCs, as a valuable source of donor cells, could offer a potential treatment avenue for injury-induced IUA.

Epigenetic alternations and targeted therapy in intrauterine adhesion: A comparative study

Although intrauterine adhesion (IUA) has been well recognized as a critical factor in infertility, little information is available regarding the molecular mechanisms. We performed a high-throughput RNA sequencing in the endometrium of three IUA patients and three normal controls. And another two gene expression profiles (PMID34968168 and GSE160365) were analyzed together. A total of 252 DEGs were identified. Cell cycle, E2F target, G2M checkpoint, integrin3 pathway and H1F1 signaling were aberrantly regulated in the IUA endometrium. 10 hub genes (CCL2, TFRC, THY1, IGF1, CTGF, SELL, SERPINE1, HBB, HBA1, LYZ) were exhibited in PPI analysis. FOXM1, IKBKB and MYC were three common transcription factors of DEGs. Five chemicals (MK-1775, PAC-1, TW-37, BIX-01294, 3-matida) were identified as putative therapeutic agents for IUA. Collectively, a series of DEGs associated with IUA were disclosed. Five chemicals and ten hub genes may be further explored as potential drugs and targets for IUA treatment.

Molecular Mechanisms of Endometriosis Revealed Using Omics Data

Endometriosis is a gynecological disorder prevalent in women of reproductive age. The primary symptoms include dysmenorrhea, irregular menstruation, and infertility. However, the pathogenesis of endometriosis remains unclear. With the advent of high-throughput technologies, various omics experiments have been conducted to identify genes related to the pathophysiology of endometriosis. This review highlights the molecular mechanisms underlying endometriosis using omics. When genes identified in omics experiments were compared with endometriosis disease genes identified in independent studies, the number of overlapping genes was moderate. However, the characteristics of these genes were found to be equivalent when functional gene set enrichment analysis was performed using gene ontology and biological pathway information. These findings indicate that omics technology provides invaluable information regarding the pathophysiology of endometriosis. Moreover, the functional characteristics revealed using enrichment analysis provide important clues for discovering endometriosis disease genes in future research.

Single-cell RNA sequencing and lineage tracing confirm mesenchyme to epithelial transformation (MET) contributes to repair of the endometrium at menstruation

The human endometrium experiences repetitive cycles of tissue wounding characterised by piecemeal shedding of the surface epithelium and rapid restoration of tissue homeostasis. In this study, we used a mouse model of endometrial repair and three transgenic lines of mice to investigate whether epithelial cells that become incorporated into the newly formed luminal epithelium have their origins in one or more of the mesenchymal cell types present in the stromal compartment of the endometrium. Using scRNAseq, we identified a novel population of PDGFRb + mesenchymal stromal cells that developed a unique transcriptomic signature in response to endometrial breakdown/repair. These cells expressed genes usually considered specific to epithelial cells and in silico trajectory analysis suggested they were stromal fibroblasts in transition to becoming epithelial cells. To confirm our hypothesis we used a lineage tracing strategy to compare the fate of stromal fibroblasts (PDGFRa+) and stromal perivascular cells (NG2/CSPG4+). We demonstrated that stromal fibroblasts can undergo a mesenchyme to epithelial transformation and become incorporated into the re-epithelialised luminal surface of the repaired tissue. This study is the first to discover a novel population of wound-responsive, plastic endometrial stromal fibroblasts that contribute to the rapid restoration of an intact luminal epithelium during endometrial repair. These findings form a platform for comparisons both to endometrial pathologies which involve a fibrotic response (Asherman's syndrome, endometriosis) as well as other mucosal tissues which have a variable response to wounding.

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

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