Endometrial stem/progenitor cells: the first 10 years

Interleukin 6 at menstruation promotes the proliferation and self-renewal of endometrial mesenchymal stromal/stem cells through the WNT/β-catenin signaling pathway

Background

At menstruation, the functional layer of the human endometrium sheds off due to the trigger of the release of inflammatory factors, including interleukin 6 (IL-6), as a result of a sharp decline in progesterone levels, leading to tissue breakdown and bleeding. The endometrial mesenchymal stem-like cells (CD140b+CD146+ eMSC) located in the basalis are responsible for the cyclical regeneration of the endometrium after menstruation. Endometrial cells from the menstruation phase have been proven to secrete a higher amount of IL-6 and further enhance the self-renewal and clonogenic activity of eMSC. However, the IL-6-responsive mechanism remains unknown. Thus, we hypothesized that IL-6 secreted from niche cells during menstruation regulates the proliferation and self-renewal of eMSC through the WNT/β-catenin signaling pathway.

Methods

In this study, the content of IL-6 across the menstrual phases was first evaluated. Coexpression of stem cell markers (CD140b and CD146) with interleukin 6 receptor (IL-6R) was confirmed by immunofluorescent staining. In vitro functional assays were conducted to investigate the effect of IL-6 on the cell activities of eMSC, and the therapeutic role of these IL-6- and WNT5A-pretreated eMSC on the repair of injured endometrium was observed using an established mouse model.

Results

The endometrial cells secrete a high amount of IL-6 under hypoxic conditions, which mimic the physiological microenvironment in the menstruation phase. Also, the expression of IL-6 receptors was confirmed in our eMSC, indicating their capacity to respond to IL-6 in the microenvironment. Exogenous IL-6 can significantly enhance the self-renewal, proliferation, and migrating capacity of eMSC. Activation of the WNT/β-catenin signaling pathway was observed upon IL-6 treatment, while suppression of the WNT/β-catenin signaling impaired the stimulatory role of IL-6 on eMSC activities. IL-6- and WNT5A-pretreated eMSC showed better performance during the regeneration of the injured mouse endometrium.

Conclusion

We demonstrate that the high level of IL-6 produced by endometrial cells at menstruation can induce the stem cells in the human endometrium to proliferate and migrate through the activation of the WNT/β-catenin pathway. Treatment of eMSC with IL-6 and WNT5A might enhance their therapeutic potential in the regeneration of injured endometrium.

The Endometrial Stem/Progenitor Cells and Their Niches

Endometrial stem/progenitor cells are a type of stem cells with the ability to self-renew and differentiate into multiple cell types. They exist in the endometrium and form niches with their neighbor cells and extracellular matrix. The interaction between endometrial stem/progenitor cells and niches plays an important role in maintaining, repairing, and regenerating the endometrial structure and function. This review will discuss the characteristics and functions of endometrial stem/progenitor cells and their niches, the mechanisms of their interaction, and their roles in endometrial regeneration and diseases. Finally, the prospects for their applications will also be explored.

Silencing p75NTR regulates osteogenic differentiation and angiogenesis of BMSCs to enhance bone healing in fractured rats

BACKGROUND

Fractures heal through a process that involves angiogenesis and osteogenesis but may also lead to non-union or delayed healing. Bone marrow mesenchymal stem cells (BMSCs) have been reported to play a pivotal role in bone formation and vascular regeneration and the p75 neurotrophin receptor (p75NTR) as being an important regulator of osteogenesis. Herein, we aim to determine the potential mediation of BMSCs by p75NTR in bone healing.

METHODS

Rat BMSCs were identified by flow cytometry (FCM) to detect cell cycle and surface markers. Then transfection of si/oe-p75NTR was performed in BMSCs, followed by Alizarin red staining to detect osteogenic differentiation of cells, immunofluorescence double staining was performed to detect the expression of p75NTR and sortilin, co-immunoprecipitation (CO-IP) was conducted to analyze the interaction between p75NTR and sortilin, and EdU staining and cell scratch assay to assess the proliferation and migration of human umbilical vein endothelial cells (HUVECs). The expression of HIF-1α, VEGF, and apoptosis-related proteins were also detected. In addition, a rat fracture healing model was constructed, and BMSCs-si-p75NTR were injected, following which the fracture condition was observed using micro-CT imaging, and the expression of platelet/endothelial cell adhesion molecule-1 (CD31) was assessed.

RESULTS

The results showed that BMSCs were successfully isolated, p75NTR inhibited apoptosis and the osteogenic differentiation of BMSCs, while si-p75NTR led to a decrease in sortilin expression in BMSCs, increased proliferation and migration in HUVECs, and upregulation of HIF-1α and VEGF expression. In addition, an interaction was observed between p75NTR and sortilin. The knockdown of p75NTR was found to reduce the severity of fracture in rats and increase the expression of CD31 and osteogenesis-related proteins.

CONCLUSION

Silencing p75NTR effectively modulates BMSCs to promote osteogenic differentiation and angiogenesis, offering a novel perspective for improving fracture healing.

Cellular heterogeneity and dynamics of the human uterus in healthy premenopausal women

The human uterus is a complex and dynamic organ whose lining grows, remodels, and regenerates in every menstrual cycle or upon tissue damage. Here we applied single-cell RNA sequencing to profile more the 50,000 uterine cells from both the endometrium and myometrium of 5 healthy premenopausal individuals, and jointly analyzed the data with a previously published dataset from 15 subjects. The resulting normal uterus cell atlas contains more than 167K cells representing the lymphatic endothelium, blood endothelium, stromal, ciliated epithelium, unciliated epithelium, and immune cell populations. Focused analyses within each major cell type and comparisons with subtype labels from prior studies allowed us to document supporting evidence, resolve naming conflicts, and to propose a consensus annotation system of 39 subtypes. We release their gene expression centroids, differentially expressed genes, and mRNA patterns of literature-based markers as a shared community resource. We find many subtypes show dynamic changes over different phases of the cycle and identify multiple potential progenitor cells: compartment-wide progenitors for each major cell type, transitional cells that are upstream of other subtypes, and potential cross-lineage multipotent stromal progenitors that may be capable of replenishing the epithelial, stromal, and endothelial compartments. When compared to the healthy premenopausal samples, a postpartum and a postmenopausal uterus sample revealed substantially altered tissue composition, involving the rise or fall of stromal, endothelial, and immune cells. The cell taxonomy and molecular markers we report here are expected to inform studies of both basic biology of uterine function and its disorders.

SIGNIFICANCE

We present single-cell RNA sequencing data from seven individuals (five healthy pre-menopausal women, one post-menopausal woman, and one postpartum) and perform an integrated analysis of this data alongside 15 previously published scRNA-seq datasets. We identified 39 distinct cell subtypes across four major cell types in the uterus. By using RNA velocity analysis and centroid-centroid comparisons we identify multiple computationally predicted progenitor populations for each of the major cell compartments, as well as potential cross-compartment, multi-potent progenitors. While the function and interactions of these cell populations remain to be validated through future experiments, the markers and their "dual characteristics" that we describe will serve as a rich resource to the scientific community. Importantly, we address a significant challenge in the field: reconciling multiple uterine cell taxonomies being proposed. To achieve this, we focused on integrating historical and contemporary knowledge across multiple studies. By providing detailed evidence used for cell classification we lay the groundwork for establishing a stable, consensus cell atlas of the human uterus.

Endometrial mesenchymal stromal/stem cells improve regeneration of injured endometrium in mice

BACKGROUND

The monthly regeneration of human endometrial tissue is maintained by the presence of human endometrial mesenchymal stromal/stem cells (eMSC), a cell population co-expressing the perivascular markers CD140b and CD146. Endometrial regeneration is impaired in the presence of intrauterine adhesions, leading to infertility, recurrent pregnancy loss and placental abnormalities. Several types of somatic stem cells have been used to repair the damaged endometrium in animal models, reporting successful pregnancy. However, the ability of endometrial stem cells to repair the damaged endometrium remains unknown.

METHODS

Electrocoagulation was applied to the left uterine horn of NOD/SCID mice causing endometrial injury. Human eMSC or PBS was then injected into the left injured horn while the right normal horn served as controls. Mice were sacrificed at different timepoints (Day 3, 7 and 14) and the endometrial morphological changes as well as the degree of endometrial injury and repair were observed by histological staining. Gene expression of various inflammatory markers was assessed using qPCR. The functionality of the repaired endometrium was evaluated by fertility test.

RESULTS

Human eMSC successfully incorporated into the injured uterine horn, which displayed significant morphological restoration. Also, endometrium in the eMSC group showed better cell proliferation and glands formation than the PBS group. Although the number of blood vessels were similar between the two groups, gene expression of VEGF-α significantly increased in the eMSC group. Moreover, eMSC had a positive impact on the regeneration of both stromal and epithelial components of the mouse endometrium, indicated by significantly higher vimentin and CK19 protein expression. Reduced endometrial fibrosis and down-regulation of fibrosis markers were also observed in the eMSC group. The eMSC group had a significantly higher gene expression of anti-inflammatory factor Il-10 and lower mRNA level of pro-inflammatory factors Ifng and Il-2, indicating the role of eMSC in regulation of inflammatory reactions. The eMSC group showed higher implantation sites than the PBS group, suggesting better endometrial receptivity with the presence of newly emerged endometrial lining.

CONCLUSIONS

Our findings suggest eMSC improves regeneration of injured endometrium in mice.

The predictive value of serum IL-17A and IL-6 expression in postoperative recurrence in patients with intrauterine adhesion

BACKGROUND

The recurrence rate of intrauterine adhesions (IUA) was high. At present, there are few studies on the relationship between proinflammatory factors IL-17A and IL-6 and IUA. The expression of serum IL-17A and IL-6 in IUA patients and their predictive value for postoperative recurrence were retrospectively analyzed.

METHODS

A total of 90 IUA patients who underwent hysteroscopic adhesion lysis in our hospital from January 2020 to January 2023 were selected as the IUA group. Patients were divided into mild, moderate, and severe IUA groups. At the same time, 60 cases of secondary infertility patients with normal endometrium were selected as the control group. The clinical baseline characteristics and serum levels of IL-17A and IL-6 were compared between control group and IUA group. To analyze the correlation and predictive value of IL-17A and IL-6 expression levels with the recurrence rate of IUA patients.

RESULTS

The preoperative levels of IL-17A and IL-6 in the IUA group were significantly higher than those in the control group. The higher the levels of inflammatory factors IL-17A and IL-6, the deeper the degree of IUA. Multivariate analysis showed that pregnancy, curettage history, IL-17A, and IL-6 levels were risk factors for IUA recurrence. In addition, the specificity and area under the curve of combining baseline data with postoperative serum IL-17A and IL-6 for predicting IUA were higher than those predicted separately.

CONCLUSION

The expression levels of serum IL-17A and IL-6 can be used as a value index to evaluate postoperative recurrence in IUA patients.

Endometrial Stem Cells: Orchestrating Dynamic Regeneration of Endometrium and Their Implications in Diverse Endometrial Disorders

The human endometrium, a vital component of the uterus, undergoes dynamic changes during the menstrual cycle to create a receptive environment for embryo implantation. Its remarkable regenerative capacity can be attributed to the presence of tissue-resident stem cell populations within the endometrium. Despite variations in characteristics among different subtypes, endometrial stem cells exhibit notably robust self-renewal capacity and the ability to differentiate into multiple lineages. This review offers a comprehensive insight into the current literature and recent advancements regarding the roles of various endometrial stem cell types during dynamic regeneration of the endometrium during the menstrual cycle. In addition, emerging evidence suggests that dysfunction or depletion of endometrial stem cells may play critical roles in the development and progression of various endometrial disorders, such as endometriosis, uterine fibroids, adenomyosis, infertility, and endometrial cancer. Therefore, we also highlight potential roles of endometrial stem cells in the development and progression of these endometrial diseases, including their ability to accumulate genetic mutations and express genes associated with endometrial diseases. Understanding the dynamic properties of the endometrium and the roles of endometrial stem cells in various endometrial disorders will shed light on potential therapeutic strategies for managing these conditions and improving women's fertility outcomes.

Comprehensive analysis of HOX family genes in endometrial cancer

Background

Endometrial cancer (EC) is one of the most prevalent malignancies in the female population. Homeoboxes (HOXs) are a large family of transcription factors that have a variety of functions in biological processes (BPs), including developmental differentiation, and their dysregulated expression has been implicated in tumorigenesis. However, the involvement of HOXs in EC has received little attention. Thus, we aimed to identify the potential role of HOXs in EC from a multi-omics perspective through bioinformatics analysis.

Methods

We obtained transcriptome, mutation, and methylation data and the corresponding clinical data for normal and tumor tissues from The Cancer Genome Atlas (TCGA) database. Abnormal expression of HOXs in EC was identified via differential analysis, and the diagnostic value of HOXs in EC was assessed with the receiver operating characteristic (ROC) method. Univariate and multivariate Cox regression models were employed to evaluate the predictive efficacy of HOXs in EC. Methylation and mutation analyses revealed epigenetic and genetic sequence alterations in HOXs. Single-sample gene set enrichment analysis (ssGSEA) was used to explore the altered immune microenvironment in EC. Moreover, the gene activity and pathway enrichment of downstream key HOX genes were revealed through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis in EC.

Results

HOXs were found to be linked to the growth of EC and potentially playing a role in establishing the tumor immune microenvironment in patients with EC. HOXB9 was found to be a vital prognostic molecule in patients with EC and is expected to contribute to a novel treatment approach.

Conclusions

We used bioinformatics techniques to clarify the potential role of HOXs from a multi-omics perspective, and our findings provide a foundation for future investigations into the molecular mechanisms of HOXs in EC.

Exploring distinct properties of endometrial stem cells through advanced single-cell analysis platforms

The endometrium is a dynamic tissue that undergoes cyclic changes in response to ovarian hormones during the menstrual cycle. These changes are crucial for pregnancy establishment and maintenance. Endometrial stem cells play a pivotal role in endometrial regeneration and repair by differentiating into various cell types within the endometrium. However, their involvement in endometrial disorders such as endometriosis, infertility, and endometrial cancer is still not fully understood yet. Traditional bulk sequencing methods have limitations in capturing heterogeneity and complexity of endometrial stem cell populations. To overcome these limitations, recent single-cell analysis techniques, including single-cell RNA sequencing (scRNA-Seq), single-cell ATAC sequencing (scATAC-Seq), and spatial transcriptomics, have emerged as valuable tools for studying endometrial stem cells. In this review, although there are still many technical limitations that require improvement, we will summarize the current state-of-the-art single-cell analysis techniques for endometrial stem cells and explore their relevance to related diseases. We will discuss studies utilizing various single-cell analysis platforms to identify and characterize distinct endometrial stem cell populations and investigate their dynamic changes in gene expression and epigenetic patterns during menstrual cycle and differentiation processes. These techniques enable the identification of rare cell populations, capture heterogeneity of cell populations within the endometrium, and provide potential targets for more effective therapies.

Body fluid-derived stem cells - an untapped stem cell source in genitourinary regeneration

Somatic stem cells have been obtained from solid organs and tissues, including the bone marrow, placenta, corneal stroma, periosteum, adipose tissue, dental pulp and skeletal muscle. These solid tissue-derived stem cells are often used for tissue repair, disease modelling and new drug development. In the past two decades, stem cells have also been identified in various body fluids, including urine, peripheral blood, umbilical cord blood, amniotic fluid, synovial fluid, breastmilk and menstrual blood. These body fluid-derived stem cells (BFSCs) have stemness properties comparable to those of other adult stem cells and, similarly to tissue-derived stem cells, show cell surface markers, multi-differentiation potential and immunomodulatory effects. However, BFSCs are more easily accessible through non-invasive or minimally invasive approaches than solid tissue-derived stem cells and can be isolated without enzymatic tissue digestion. Additionally, BFSCs have shown good versatility in repairing genitourinary abnormalities in preclinical models through direct differentiation or paracrine mechanisms such as pro-angiogenic, anti-apoptotic, antifibrotic, anti-oxidant and anti-inflammatory effects. However, optimization of protocols is needed to improve the efficacy and safety of BFSC therapy before therapeutic translation.

Junctional zone thickening: an endo-myometrial unit disorder

Adenomyosis is a disease defined by histopathology, mostly of hysterectomy specimens, and classification is challenged by the disagreement of the histologic definition. With the introduction of Magnetic Resonance Imaging (MRI) and two- and three-dimensional ultrasound, the diagnosis of adenomyosis became a clinical entity. In MRI and US, adenomyosis ranges from thickening of the inner myometrium or junctional zone to nodular, cystic, or diffuse lesions involving the entire uterine wall, up to a well-circumscribed adenomyoma or a polypoid adenomyoma. The absence of an accepted classification and the vague and inconsistent terminology hamper basic and clinical research. The sub-endometrial halo seen at US and MRI is a distinct entity, differing from the outer myometrium by its increased nuclear density and vascular structure. The endometrium and the sub-endometrial muscularis or archimetra are of Müllarian origin, while the outer myometrium is non-Mullerian mesenchymal. The junctional zone (JZ) is important for uterine contractions, conception, implantation, and placentation. Thickening of the JZ can be considered inner myometrium adenomyosis, with or without endometrial invasion. Changes in the JZ should be considered a different entity than myometrial clinically associated with impaired conception, implantation, abnormal uterine bleeding, pelvic pain and obstetrical outcome. Pathology of the basal endometrium and JZ is a separate entity and should be identified as an endo-myometrial unit disorder (EMUD).

The effects of intraovarian injection of autologous menstrual blood-derived mesenchymal stromal cells on pregnancy outcomes in women with poor ovarian response

BACKGROUND

Assisted reproduction faces a significant obstacle in the form of poor ovarian response (POR) to controlled ovarian stimulation. To address this challenge, mesenchymal stem cell therapy has been proposed as a potential treatment for female infertility and/or restoration of ovarian function in POR women. Our previous research has demonstrated that menstrual blood-derived-mesenchymal stromal cells (MenSCs) injected into the ovaries of women with POR can increase pregnancy rates. The objective of this study was to examine whether MenSC therapy could enhance ovarian reserve parameters and pregnancy outcomes in a larger population of individuals with POR.

METHOD

This study consisted of 180 infertile individuals with POR who declined oocyte donation. Participants were divided into two groups: those who received bilateral MenSCs intraovarian injection and those who received no intervention. Our primary aim was to compare the rates of spontaneous pregnancy between the two groups, followed by an investigation of any alterations in the ovarian reserve parameters, such as serum FSH, AMH, and AFC levels, as well as the ICSI/IVF outcomes, in both groups of participants.

RESULTS

The MenSC therapy exhibited a favourable tolerability profile and did not raise any safety concerns. Following the 2-month follow-up period, women who received MenSC treatment demonstrated a significantly higher rate of spontaneous pregnancy (P < 0.005) and an improvement in anti-Müllerian hormone (AMH) levels (P = 0.0007) and antral follicle count (AFC) (P < 0.001), whereas the control group demonstrated a considerable decline in these parameters (Both P < 0.001). The MenSC therapy led to a greater number of mature oocytes and embryos among women who underwent ICSI/IVF. Our age subgroup analysis demonstrated a significant difference in the number of spontaneous pregnancies and ICSI/IVF outcomes between the treatment and control groups only among individuals below 40 years of age.

CONCLUSION

The results of our study indicate that MenSCs treatment may be a viable option for treating women experiencing POR. However, in order to be widely implemented in clinical practice, the clinical effectiveness of MenSCs therapy will need to be established through rigorous prospective randomized clinical trials.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05703308. Registered 01/26/2023, retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05703308 . IRCT, IRCT20180619040147N4. Registered 08/01/2020.

Menstrual blood-derived endometrial stem cell, a unique and promising alternative in the stem cell-based therapy for chemotherapy-induced premature ovarian insufficiency

Chemotherapy can cause ovarian dysfunction and infertility since the ovary is extremely sensitive to chemotherapeutic drugs. Apart from the indispensable role of the ovary in the overall hormonal milieu, ovarian dysfunction also affects many other organ systems and functions including sexuality, bones, the cardiovascular system, and neurocognitive function. Although conventional hormone replacement therapy can partly relieve the adverse symptoms of premature ovarian insufficiency (POI), the treatment cannot fundamentally prevent deterioration of POI. Therefore, effective treatments to improve chemotherapy-induced POI are urgently needed, especially for patients desiring fertility preservation. Recently, mesenchymal stem cell (MSC)-based therapies have resulted in promising improvements in chemotherapy-induced ovary dysfunction by enhancing the anti-apoptotic capacity of ovarian cells, preventing ovarian follicular atresia, promoting angiogenesis and improving injured ovarian structure and the pregnancy rate. These improvements are mainly attributed to MSC-derived biological factors, functional RNAs, and even mitochondria, which are directly secreted or indirectly translocated with extracellular vesicles (microvesicles and exosomes) to repair ovarian dysfunction. Additionally, as a novel source of MSCs, menstrual blood-derived endometrial stem cells (MenSCs) have exhibited promising therapeutic effects in various diseases due to their comprehensive advantages, such as periodic and non-invasive sample collection, abundant sources, regular donation and autologous transplantation. Therefore, this review summarizes the efficacy of MSCs transplantation in improving chemotherapy-induced POI and analyzes the underlying mechanism, and further discusses the benefit and existing challenges in promoting the clinical application of MenSCs in chemotherapy-induced POI.

Exploration of eMSCs with HA-GEL system in repairing damaged endometrium after endometrial cancer with fertility-sparing treatment

Despite the high complete response rate of fertility-sparing treatment in early-stage endometrial cancer (EC), the low pregnancy rate is a clinical challenge. Whether endometrium-derived mesenchymal stem cells (eMSCs) can repair damaged endometrium after EC reversal remains unclear. This study explored the potential therapeutic effects of eMSCs with suitable scaffold materials on endometrial damage caused by EC. Here, appropriate engineering scaffold materials were compared to identify the most suitable materials to carry eMSCs. Then, safety and efficacy evaluations of eMSCs with a suitable hyaluronic acid hydrogel (eMSCs/HA-GEL) were investigated in in vivo experiments with subcutaneous xenotransplantation in Balb/C nude mice and a model of endometrial mechanical injury in rats. HA-GEL has minimal cytotoxicity to eMSCs compared to other materials. Then, in vitro experiments demonstrate that eMSCs/HA-GEL enhance the inhibitory effects of progestins on EC cell biological behaviors. eMSCs/HA-GEL significantly inhibit EC cell growth and have no potential safety hazards of spontaneous tumorigenesis in Balb/C nude mouse subcutaneous xenotransplantation assays. eMSCs/HA-GEL intrauterine transplantation effectively increases endometrial thickness and glandular number, improves endometrial blood supply, reduces fibrotic areas, and improves pregnancy rates in a rat endometrial mechanical injury model. GFP-eMSCs/HA-GEL intrauterine transplantation in rats shows more GFP-eMSCs in the endometrium than GFP-eMSCs transplantation alone, and no tumor formation or suspicious cell nodules are found in the liver, kidney, or lung tissues. Our results reveal the safety and efficacy of eMSCs/HA-GEL in animal models and provide preliminary evidence for the use of eMSCs/HA-GEL as a treatment for EC-related endometrial damage.

Novel therapeutic strategies for injured endometrium: intrauterine transplantation of menstrual blood‑derived cells from infertile patients

BACKGROUND

Menstrual blood-derived cells show regenerative potential as a mesenchymal stem cell and may therefore be a novel stem cell source of treatment for refractory infertility with injured endometrium. However, there have been few pre-clinical studies using cells from infertile patients, which need to be addressed before establishing an autologous transplantation. Herein, we aimed to investigate the therapeutic capacity of menstrual blood-derived cells from infertile patients on endometrial infertility.

METHODS

We collected menstrual blood-derived cells from volunteers and infertile patients and confirmed their mesenchymal stem cell phenotype by flow cytometry and induction of tri-lineage differentiation. We compared the proliferative and paracrine capacities of these cells. Furthermore, we also investigated the regenerative potential and safety concerns of the intrauterine transplantation of infertile patient-derived cells using a mouse model with mechanically injured endometrium.

RESULTS

Menstrual blood-derived cells from both infertile patients and volunteers showed phenotypic characteristics of mesenchymal stem cells. In vitro proliferative and paracrine capacities for wound healing and angiogenesis were equal for both samples. Furthermore, the transplantation of infertile patient-derived cells into uterine horns of the mouse model ameliorated endometrial thickness, prevented fibrosis, and improved fertility outcomes without any apparent complications.

CONCLUSIONS

In our pre-clinical study, intrauterine transplantation of menstrual blood-derived cells may be a novel and attractive stem cell source for the curative and prophylactic therapy for injured endometrium. Further studies will be warranted for future clinical application.

Conditioned medium of human menstrual blood-derived endometrial stem cells protects against cell inflammation and apoptosis of Npc1KO N2a cells

Niemann-Pick disease type C1 (NPC1) is a hereditary neurodegenerative disorder caused by a mutation in the NPC1 gene. This gene encodes a transmembrane protein found in lysosomes. This disease characterized by hepatosplenomegaly, neurological impairments and premature death. Recent preclinical studies have shown promising results in using mesenchymal stem cells (MSCs) to alleviate the symptoms of NPC1. One type of MSCs, known as human menstrual blood-derived endometrial stem cells (MenSCs), has attracted attention due to its accessibility, abundant supply, and strong proliferation and regeneration capabilities. However, it remains uncertain whether the conditioned medium of MenSCs (MenSCs-CM) can effectively relieve the symptoms of NPC1. To investigate this further, we employed the CRISPR-Cas9 technique to successfully create a Npc1 gene knockout N2a cell line (Npc1KO N2a). Sanger sequencing confirmed the occurrence of Npc1 gene mutation in these cells, while western blotting revealed a lack of NPC1 protein expression. Filipin staining provided visual evidence of unesterified cholesterol accumulation in Npc1KO N2a cells. Moreover, Npc1KO N2a cells exhibited significantly decreased viability, increased inflammation, and heightened cell apoptosis. Notably, our study demonstrated that the viability of Npc1KO N2a cells was most significantly improved after being cultured by 36 h-collected MenSCs-CM for 0.5 days. Additionally, MenSCs-CM exhibited the ability to effectively reduce inflammation, counteract cell apoptosis, and ameliorate unesterified cholesterol accumulation in Npc1KO N2a cells. This groundbreaking finding establishes, for the first time, the protective effect of MenSCs-CM on N2a cells with Npc1 gene deletion. These findings suggest that the potential of MenSCs-CM as a beneficial therapeutic approach for NPC1 and other neurodegenerative diseases.

CD73 mediates the therapeutic effects of endometrial regenerative cells in concanavalin A-induced hepatitis by regulating CD4+ T cells

BACKGROUND

As a kind of mesenchymal-like stromal cells, endometrial regenerative cells (ERCs) have been demonstrated effective in the treatment of Concanavalin A (Con A)-induced hepatitis. However, the therapeutic mechanism of ERCs is not fully understood. Ecto-5`-nucleotidase (CD73), an enzyme that could convert immune-stimulative adenosine monophosphate (AMP) to immune-suppressive adenosine (ADO), was identified highly expressed on ERCs. The present study was conducted to investigate whether the expression of CD73 on ERCs is critical for its therapeutic effects in Con A-induced hepatitis.

METHODS

ERCs knocking out CD73 were generated with lentivirus-mediated CRISPR-Cas9 technology and identified by flow cytometry, western blot and AMPase activity assay. CD73-mediated immunomodulatory effects of ERCs were investigated by CD4+ T cell co-culture assay in vitro. Besides, Con A-induced hepatitis mice were randomly assigned to the phosphate-buffered saline treated (untreated), ERC-treated, negative lentiviral control ERC (NC-ERC)-treated, and CD73-knockout-ERC (CD73-KO-ERC)-treated groups, and used to assess the CD73-mediated therapeutic efficiency of ERCs. Hepatic histopathological analysis, serum transaminase concentrations, and the proportion of CD4+ T cell subsets in the liver and spleen were performed to assess the progression degree of hepatitis.

RESULTS

Expression of CD73 on ERCs could effectively metabolize AMP to ADO, thereby inhibiting the activation and function of conventional CD4+ T cells was identified in vitro. In addition, ERCs could markedly reduce levels of serum and liver transaminase and attenuate liver damage, while the deletion of CD73 on ERCs dampens these effects. Furthermore, ERC-based treatment achieved less infiltration of CD4+ T and Th1 cells in the liver and reduced the population of systemic Th1 and Th17 cells and the levels of pro-inflammatory cytokines such as IFN-γ and TNF-α, while promoting the generation of Tregs in the liver and spleen, while deletion of CD73 on ERCs significantly impaired their immunomodulatory effects locally and systemically.

CONCLUSION

Taken together, it is concluded that CD73 is critical for the therapeutic efficiency of ERCs in the treatment of Con A-induced hepatitis.

Targeting endometrial inflammation in intrauterine adhesion ameliorates endometrial fibrosis by priming MSCs to secrete C1INH

Intrauterine adhesion (IUA) is a common cause of uterine infertility and its histopathologic characteristic is endometrial fibrosis. A shortage of stem cells in the endometrial basalis has been recognized as a common cause of IUA development because approximately 90% of patients suffer from IUA after endometrial injury. In this study, we provide evidence that persistent inflammation is the main contributor to endometrial fibrosis in IUA patients. We further found that treating an IUA-like mouse model with ITI-hUC-MSCs (hUC-MSCs reprogrammed by IL-1β, TNF-α and IFN-γ) significantly decreased endometrial inflammation and fibrosis. Mechanistically, high levels of complement 1 inhibitor (C1INH) secreted by ITI-hUC-MSCs prevented inflammation from inducing profibrotic CD301+ macrophage polarization by downregulating the JAK-STAT signaling pathway. In conclusion, persistent inflammation in the endometria of IUA patients provides macrophage polarization with a profibrotic niche to promote endometrial fibrosis, and the powerful immunomodulatory effects of ITI-hUC-MSCs improve the immune microenvironment of endometrial regeneration.

Research advances in drug therapy of endometriosis

Endometriosis is one of the most common benign gynecological disorders in reproductive-aged women. The major symptoms are chronic pelvic pain and infertility. Despite its profound impact on women's health and quality of life, its pathogenesis has not been fully elucidated, it cannot be cured and the long-term use of drugs yields severe side effects and hinders fertility. This review aims to present the advances in pathogenesis and the newly reported lead compounds and drugs managing endometriosis. This paper investigated Genetic changes, estrogen-dependent inflammation induction, progesterone resistance, imbalance in proliferation and apoptosis, angiogenesis, lymphangiogenesis and neurogenesis, and tissue remodeling in its pathogenesis; and explored the pharmacological mechanisms, constitutive relationships, and application prospects of each compound in the text. To date, Resveratrol, Bay1316957, and bardoxifene were effective against lesions and pain in controlled animal studies. In clinical trials, Quinagolide showed no statistical difference with the placebo group; the results of phase II clinical trial of the IL-33 antibody have not been announced yet; clinical trial stage III of vilaprisan was suspended due to drug toxicity. Elagolix was approved for the treatment of endometriosis-related pain, but clinical studies of Elagolix for the pretreatment of patients with endometriosis to before In vitro fertilization treatment have not been fulfilled. The results of a clinical study of Linzagolix in patients with moderate to severe endometriosis-related pain have not been disclosed yet. Letrozole improved the fertility of patients with mild endometriosis. For endometriosis patients with infertility, oral GnRH antagonists and aromatase inhibitors are promising drugs, especially Elagolix and Letrozole.

Endometrial and placental stem cells in successful and pathological pregnancies

The endometrium is a dynamic tissue that undergoes extensive remodeling during the menstrual cycle and further gets modified during pregnancy. Different kinds of stem cells are reported in the endometrium. These include epithelial stem cells, endometrial mesenchymal stem cells, side population stem cells, and very small embryonic-like stem cells. Stem cells are also reported in the placenta which includes trophoblast stem cells, side population trophoblast stem cells, and placental mesenchymal stem cells. The endometrial and placental stem cells play a pivotal role in endometrial remodeling and placental vasculogenesis during pregnancy. The dysregulation of stem cell function is reported in various pregnancy complications like preeclampsia, fetal growth restriction, and preterm birth. However, the mechanisms by which it does so are yet elusive. Herein, we review the current knowledge of the different type of stem cells involved in pregnancy initiation and also highlight how their improper functionality leads to pathological pregnancy.

Is neonatal uterine bleeding responsible for early-onset endometriosis?

BACKGROUND

It has been hypothesized that the origin of early-onset endometriosis could be from endometrial mesenchymal stem cells (eMSCs) in neonatal uterine blood (NUB). There is no information on the possible mechanistic basis linking an association between NUB/neonatal endometrium and development of early-onset endometriosis. In this study we performed a series of experiments to clarify the mechanistic link between NUB and/or neonatal endometrium and development of early-onset endometriosis.

METHODS

We retrospectively collected postmortem neonatal endometria (n = 15) and prospectively collected NUB (n = 18) of female babies for the analysis of different biological markers including eMSCs. Immunohistochemical analysis of neonatal endometria was performed to examine the expression patterns of ovarian steroid receptors (ER/PGR), decidualization (prolactin, IGFBP1), pre-decidualization (Glycodelin A, α-SMA), proliferation (Ki-67 index), vascularity (CD31 + cells), immunocompetent CD68+, CD45+, CD56 + cells and some putative markers of eMSCs. Cell transfer method and immunocytochemistry were used to investigate the eMSCs and/or endometrial cells in NUB.

RESULTS

Immunohistochemical analysis of postmortem neonatal endometria revealed variable staining response to ER/PGR, decidual markers, and substantial proliferative and angiogenic activity. A moderate to strong immunoexpression of Glycodelin-A was found in both neonatal and adult endometria. The tissue infiltration of CD56+, CD45 + and CD68 + immunocompetent cells was significantly low in neonatal endometria than that in adult endometria (p = 0.0003, p < 0.0001, p = 0.034, respectively). No eMSCs or even endometrial cells were detected in NUB. However, a variable expression of some phenotypes of eMSCs (CD90/CD105) was found in neonatal endometria.

CONCLUSIONS

Based on our serial experiments we did not find any supporting evidence for the role of NUB in early-onset endometriosis. Neonatal endometria showed variable expression of ovarian steroid receptors, decidualization, and a substantial amount of proliferative and angiogenic activity. As an alternative mechanism, a significantly less tissue accumulation of immunocompetent cells in neonatal endometria may explain the survival of ER + and PGR + cells should they make entry into the pelvis and consequent development of early endometriosis with the onset of ovarian function. Future study with large sample size and application of modified technological tools is warranted to test the NUB hypothesis and to clarify their biological or clinical significance.

TRIAL REGISTRATION

not applicable.

Human menstrual blood-derived stem cells alleviate autoimmune hepatitis via JNK/MAPK signaling pathway in vivo and in vitro

Autoimmune hepatitis (AIH) is a severe globally distributed liver disease that could occur at any age. Human menstrual blood-derived stem cells (MenSCs) have shown therapeutic effect in acute lung injury and liver failure. However, their role in the curative effect of AIH remains unclear. Here, a classic AIH mouse model was constructed through intravenous injection with concanavalin A (Con A). MenSCs were intravenously injected while Con A injection in the treatment groups. The results showed that the mortality by Con A injection was significantly decreased by MenSCs treatment and liver function tests and histological analysis were also ameliorated. The results of phosphoproteomic analysis and RNA-seq revealed that MenSCs improved AIH, mainly by apoptosis and c-Jun N-terminal kinase/mitogen-activated protein signaling pathways. Apoptosis analysis demonstrated that the protein expression of cleaved caspase 3 was increased by Con A injection and reduced by MenSCs transplantation, consistent with the TUNEL staining results. An AML12 co-culture system and JNK inhibitor (SP600125) were used to verify the JNK/MAPK and apoptosis signaling pathways. These findings suggested that MenSCs could be a promising strategy for AIH.

Novel in vivo endometriotic models associated eutopic endometrium by implanting menstrual blood-derived stromal cells from patients with endometriosis

The eutopic endometrium provides novel insights into endometriotic pathophysiology and treatment. However, no in vivo models currently available are suitable for eutopic endometrium in endometriosis. In this study, we present new endometriotic in vivo models associated with eutopic endometrium using menstrual blood-derived stromal cells (MenSCs). First, we isolated endometriotic MenSCs (E-MenSCs) and healthy MenSCs (H-MenSCs) from the menstrual blood of patients with endometriosis (n = 6) and healthy volunteers (n = 6). Then, we identified MenSCs' endometrial stromal cell properties using adipogenic and osteogenic differentiation. A cell counting kit-8 and wound healing assay were used to compare the proliferation and migration capability between E-MenSCs and H-MenSCs. Seventy female nude mice were used to prepare endometriotic models related to eutopic endometrium by implanting E-MenSCs relying on three approaches, including surgical implantation using scaffolds seeded with MenSCs, and subcutaneous injection of MenSCs in the abdomen and the back (n = 10). H-MenSCs or scaffolds only were implanted in control groups (n = 10). One month after the surgical implantation and 1 week after the subcutaneous injection, we evaluated modeling by hematoxylin-eosin (H&E) and immunofluorescent staining of human leukocyte antigen α (HLAA). Fibroblast morphology, lipid droplets, and calcium nodules in E-MenSCs and H-MenSCs identified their endometrial stromal cell properties. We noticed that the proliferation and migration of E-MenSCs were considerably enhanced compared to H-MenSCs (P < 0.05). E-MenSCs implanted in nude mice formed ectopic lesions using three approaches (n = 10; lesions formation rate: 90%, 115%, and 80%; average volumes: 123.60, 27.37, and 29.56 mm3), while H-MenSCs in the nude mice shaped nothing at the implantation sites. Endometrial glands, stroma, and HLAA expression in these lesions further verified the success and applicability of the proposed endometriotic modeling. Findings provide in vitro and in vivo models and paired controls associated with eutopic endometrium in women with endometriosis using E-MenSCs and H-MenSCs. The approach of subcutaneous injection of MenSCs in the abdomen is highlighted due to non-invasive, simple, and safe steps, a short modeling period (1 week), and an excellent modeling success rate (115%), which could improve the repeats and success of endometriotic nude mice model and shorten the modeling period. These novel models could nearly intimate human eutopic endometrial mesenchymal stromal cells in the progress of endometriosis, opening a new path for disease pathology and treatment.

Characterization of canine adipose- and endometrium-derived Mesenchymal Stem/Stromal Cells and response to lipopolysaccharide

Mesenchymal stem/stromal cells (MSCs) are used for regenerative therapy in companion animals. Their potential was initially attributed to multipotency, but subsequent studies in rodents, humans and veterinary species evidenced that MSCs produce factors that are key mediators of immune, anti-infective and angiogenic responses, which are essential in tissue repair. MSCs preparations have been classically obtained from bone marrow and adipose tissue (AT) in live animals, what requires the use of surgical procedures. In contrast, the uterus, which is naturally exposed to external insult and infection, can be accessed nonsurgically to obtain samples, or tissues can be taken after neutering. In this study, we explored the endometrium (EM) as an alternative source of MSCs, which we compared with AT obtained from canine paired samples. Canine AT- and EM-MSCs, formed CFUs when seeded at low density, underwent tri-lineage differentiation into adipocytes, osteocytes and chondrocytes, and expressed the CD markers CD73, CD90 and CD105, at equivalent levels. The immune genes IL8, CCL2 and CCL5 were equally expressed at basal levels by both cell types. However, in the presence of the inflammatory stimulus lipopolysaccharide (LPS), expression of IL8 was higher in EM- than in AT-MSCs (p < 0.04) while the other genes were equally elevated in both cell types (p < 0.03). This contrasted with the results for CD markers, where the expression was unaltered by exposing the MSCs to LPS. Overall, the results indicate that canine EM-MSCs could serve as an alternative cell source to AT-MSCs in therapeutic applications.

Decidual cells and decidualization in the carnivoran endotheliochorial placenta

Decidualization is considered a distinctive feature of eutherian pregnancy, and has appeared during evolution along with the development of invasive forms of placentation, as the endotheliochorial placenta. Although decidualization is not massive in carnivores, as it is in most species developing hemochorial placentas, isolated or grouped cells regarded as decidual have been documented and characterized, mainly in bitches and queens. For the majority of the remaining species of the order, data in the bibliography are fragmentary. In this article, general morphological aspects of decidual stromal cells (DSCs), their time of appearance and lasting, data about the expression of cytoskeletal proteins and molecules considered as markers of decidualization were reviewed. From the data reviewed, it follows that carnivoran DSCs take part either in the secretion of progesterone, prostaglandins, relaxin, among other substances, or at least in the signaling pathways triggered by them. Beyond their physiological roles, some of those molecules are already being used, or are yet under study, for the non-invasive endocrine monitoring and reproductive control of domestic and wild carnivores. Only insulin-like growth factor binding protein 1, among the main decidual markers, has been undoubtedly demonstrated in both species. Laminin, on the contrary, was found only in feline DSCs, and prolactin was preliminary reported in dogs and cats. Prolactin receptor, on the other hand, was found in both species. While canine DSCs are the only placental cell type expressing the nuclear progesterone receptor (PGR), that receptor has not been demonstrated neither in feline DSCs, nor in any other cell in the queen placenta, although the use of PGR blockers leads to abortion. Against this background, and from the data gathered so far, it is unquestionable that DSCs in carnivorans do play a pivotal role in placental development and health. The knowledge about placental physiology is critical for medical care and breeding management, primarily in domestic carnivores; it is also absolutely crucial for a conservation approach in the management of endangered carnivore species.

Archimetrosis: the evolution of a disease and its extant presentation : Pathogenesis and pathophysiology of archimetrosis (uterine adenomyosis and endometriosis)

PURPOSE

This article presents a novel concept of the evolution and, thus, the pathogenesis of uterine adenomyosis as well as peritoneal and peripheral endometriosis. Presently, no unifying denomination of this nosological entity exists.

METHODS

An extensive search of the literature on primate evolution was performed. This included comparative functional morphology with special focus on the evolution of the birthing process that fundamentally differs between the haplorrhine primates and most of the other eutherian mammals. The data were correlated with the results of own research on the pathophysiology of human archimetrosis and with the extant presentation of the disease.

RESULTS

The term Archimetrosis is suggested as a denomination of the nosological entity. Archimetrosis occurs in human females and also in subhuman primates. There are common features in the reproductive process of haplorrhine primates such as spontaneous ovulation and corpus luteum formation, spontaneous decidualization and menstruation. These have fused Müllerian ducts resulting in a uterus simplex. Following a usually singleton pregnancy, the fetus is delivered in the skull position. Some of these features are shared by other mammals, but not in that simultaneous fashion. In haplorrhine primates, with the stratum vasculare, a new myometrial layer has evolved during the time of the Cretaceous-Terrestrial Revolution (KTR) that subserves expulsion of the conceptus and externalization of menstrual debris in non-conceptive cycles. Hypercontractility of this layer has evolved as an advantage with respect to the survival of the mother and the birth of a living child during delivery and may be experienced as primary dysmenorrhea during menstruation. It may result in tissue injury by the sheer power of the contractions and possibly by the associated uterine ischemia. Moreover, the lesions at extra-uterine sites appear to be maintained by biomechanical stress.

CONCLUSIONS

Since the pathogenesis of archimetrosis is connected with the evolution of the stratum vasculare, tissue injury and repair (TIAR) turns out to be the most parsimonious explanation for the development of the disease based on clinical, experimental and evolutionary evidence. Furthermore, a careful analysis of the published clinical data suggests that, in the risk population with uterine hypercontractility, the disease develops with a yet to be defined latency phase after the onset of the biomechanical injury. This opens a new avenue of prevention of the disease in potentially affected women that we consider to be primarily highly fertile.

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.

Research progress of stem cell therapy for endometrial injury

Endometrial damage is an important factor leading to infertility and traditional conventional treatments have limited efficacy. As an emerging technology in recent years, stem cell therapy has provided new hope for the treatment of this disease. By comparing the advantages of stem cells from different sources, it is believed that menstrual blood endometrial stem cells have a good application prospect as a new source of stem cells. However, the clinical utility of stem cells is still limited by issues such as colonization rates, long-term efficacy, tumor formation, and storage and transportation. This paper summarizes the mechanism by which stem cells repair endometrial damage and clarifies the material basis of their effects from four aspects: replacement of damaged sites, paracrine effects, interaction with growth factors, and other new targets. According to the pathological characteristics and treatment requirements of intrauterine adhesion (IUA), the research work to solve the above problems from the aspects of functional bioscaffold preparation and multi-functional platform construction is also summarized. From the perspective of scaffold materials and component functions, this review will provide a reference for comprehensively optimizing the clinical application of stem cells.

Endometriosis-associated infertility: From pathophysiology to tailored treatment

Despite the clinically recognized association between endometriosis and infertility, the mechanisms implicated in endometriosis-associated infertility are not fully understood. Endometriosis is a multifactorial and systemic disease that has pleiotropic direct and indirect effects on reproduction. A complex interaction between endometriosis subtype, pain, inflammation, altered pelvic anatomy, adhesions, disrupted ovarian reserve/function, and compromised endometrial receptivity as well as systemic effects of the disease define endometriosis-associated infertility. The population of infertile women with endometriosis is heterogeneous, and diverse patients' phenotypes can be observed in the clinical setting, thus making difficult to establish a precise diagnosis and a single mechanism of endometriosis related infertility. Moreover, clinical management of infertility associated with endometriosis can be challenging due to this heterogeneity. Innovative non-invasive diagnostic tools are on the horizon that may allow us to target the specific dysfunctional alteration in the reproduction process. Currently the treatment should be individualized according to the clinical situation and to the suspected level of impairment. Here we review the etiology of endometriosis related infertility as well as current treatment options, including the roles of surgery and assisted reproductive technologies.

Optimizing human endometrial mesenchymal stem cells for maximal induction of angiogenesis

Human endometrial mesenchymal stem cells (hEMSCs) have been shown to promote neo-vascularization; however, its angiogenic function lessens with age. To determine the optimal conditions for maximizing hEMSC angiogenic capacity, we examined the effects of serial passaging on hEMSC activity. hEMSCs were cultured from passages (P) 3, 6, 9, and 12, and analyzed for proliferation, migration, differentiation and senescence, as well as their capacity to induce angiogenesis. The results showed that hEMSC proliferation and migration significantly decreased after P12. Furthermore, hEMSC differentiation into adipogenic and osteogenic lineages, as well as their proangiogenic capacity, gradually decreased from P9-12, while senescence only occurred after P12. Evaluation of angiogenic-related protein levels showed that both transforming growth factor β2 and Tie-2 was significantly reduced in hEMSCs at P12, compared to P3, possibly serving as the basis behind their lowered angiogenic capacity. Furthermore, in vivo angiogenesis evaluation with Matrigel plug assay showed that the optimal hEMSC to HUVEC ratio, for maximizing vessel formation, was 1:4. This study showed that hEMSC passaging was associated with lowered cellular functioning, bringing them closer to a senescent phenotype, especially after P12, thereby defining the optimal time period for cultivating fully functional hEMSCs for therapeutic applications.

Protocol for the Endometriosis Research Queensland Study (ERQS): an integrated cohort study approach to improve diagnosis and stratify treatment

INTRODUCTION

Endometriosis is a common gynaecological disease associated with pelvic pain and subfertility. There are no non-invasive diagnostic tests, medical management requires suppression of oestrogens and surgical removal is associated with risk. Endometriosis is a complex genetic disease with variants in at least 27 genetic regions associated with susceptibility. Previous research has implicated a variety of biological mechanisms in multiple cell types. Endometrial and endometriotic epithelial cells acquire somatic mutations at frequency higher than expected in normal tissue. Stromal cells have altered adhesive capacity and immune cells show altered cytotoxicity. Understanding the functional consequences of these genetic variants on each cell type requires the collection of patient symptoms, clinical and genetic data and disease-relevant tissue in an integrated program.

METHODS AND ANALYSIS

The aims of this study are to collect tissue associated with endometriosis, chart the genetic architecture related to endometriosis in this tissue, isolate and propagate patient-specific cellular models, understand the functional consequence of these genetic variants and how they interact with environmental factors in pathogenesis and treatment response.We will collect patient information from online questionnaires prior to surgery and at 6 and 12 months postsurgery. Treating physicians will document detailed surgical data. During surgery, we will collect blood, peritoneal fluid, endometrium and endometriotic tissue. Tissue will be used to isolate and propagate in vitro models of individual cells. Genome wide genotyping and gene expression data will be generated. Somatic mutations will be identified via whole genome sequencing.

ETHICS AND DISSEMINATION

The study has been approved and will be monitored by the Metro North Human Research Ethics committee (HREC) and research activities at the University of Queensland (UQ) will be overseen by the UQ HREC with annual reports submitted. Research results will be published in peer-reviewed journals and presented at conferences were appropriate. This study involves human participants and was approved by RBWH Human Research Ethics Committee; HREC/2019/QRBW/56763.The University of Queensland; 2017002744. Participants gave informed consent to participate in the study before taking part.

The role of Notch signaling in endometrial mesenchymal stromal/stem-like cells maintenance

Human endometrium undergoes cycles of regeneration in women of reproductive age. The endometrial mesenchymal stromal/stem cells (eMSC) contribute to this process. Notch signaling is essential for homeostasis of somatic stem cells. However, its role in eMSC remains unclear. We show with gain- and loss-of-function experiments that activation of Notch signaling promotes eMSC maintenance, while inhibition induces opposite effect. The activation of Notch signaling better maintains eMSC in a quiescent state. However, these quiescent eMSC can re-enter the cell cycle depending on the Notch and Wnt activities in the microenvironment, suggesting a crosstalk between the two signaling pathways. We further show that the Notch signaling is involved in endometrial remodeling event in a mouse menstrual-like model. Suppression of Notch signaling reduces the proliferation of Notch1⁺ label-retaining stromal cells and delays endometrial repair. Our data demonstrate the importance of Notch signaling in regulating the endometrial stem/progenitor cells in vitro and in vivo.

Notch signaling promotes the quiescent state of endometrial mesenchymal stromal/stem cells (eMSC), whose re-rentry into the cell cycle is in turn influenced by Notch and Wnt signaling from the microenvironment.

What Do the Transcriptome and Proteome of Menstrual Blood-Derived Mesenchymal Stem Cells Tell Us about Endometriosis?

Given the importance of menstrual blood in the pathogenesis of endometriosis and the multifunctional roles of menstrual mesenchymal stem cells (MenSCs) in regenerative medicine, this issue has gained prominence in the scientific community. Moreover, recent reviews highlight how robust the integrated assessment of omics data are for endometriosis. To our knowledge, no study has applied the multi-omics approaches to endometriosis MenSCs. This is a case-control study at a university-affiliated hospital. MenSCs transcriptome and proteome data were obtained by RNA-seq and UHPLC-MS/MS detection. Among the differentially expressed proteins and genes, we emphasize ATF3, ID1, ID3, FOSB, SNAI1, NR4A1, EGR1, LAMC3, and ZFP36 genes and MT2A, TYMP, COL1A1, COL6A2, and NID2 proteins that were already reported in the endometriosis. Our functional enrichment analysis reveals integrated modulating signaling pathways such as epithelial–mesenchymal transition (↑) and PI3K signaling via AKT to mTORC1 (↓ in proteome), mTORC1 signaling, TGF beta signaling, TNFA signaling via NFkB, IL6 STAT3 signaling, and response to hypoxia via HIF1A targets (↑ in transcriptome). Our findings highlight primary changes in the endometriosis MenSCs, suggesting that the chronic inflammatory endometrial microenvironment can modulate these cells, providing opportunities for endometriosis etiopathogenesis. Moreover, they identify challenges for future research leveraging knowledge for regenerative and precision medicine in endometriosis.

Expression of Fucosyltransferase 4 (FUT4) mRNA Is Increased in Endometrium from Women with Endometriosis

Endometriosis is a common gynecological disorder defined as the presence of endometrial-like tissue (glands and stroma) outside the uterus. The etiopathogenesis of endometriosis is still poorly recognized. It is speculated that stage-specific embryonic antigen 1 (SSEA-1)-positive stem-like glandular epithelial cells may contribute to the development of the disease. The synthesis of SSEA-1 is mediated by fucosyltransferase 4 encoded by the FUT4 gene. Therefore, this study aimed to evaluate the specific expression of FUT4 mRNA in biopsies of the endometrium from women with and without endometriosis. FUT4 mRNA levels were examined in 49 women with laparoscopically confirmed endometriosis and 28 controls by means of quantitative reverse-transcription polymerase chain reaction (qRT-PCR). The expression of FUT4 mRNA was significantly increased in the endometrium of patients with endometriosis when compared to the controls (p < 0.0001). Expression of FUT4 mRNA in the endometrium was correlated with the severity of endometriosis (rs = 0.5579, p < 0.0001); however, there were no differences in endometrial FUT4 mRNA expression when comparing endometriotic lesions from various locations. The discriminatory ability of FUT4 mRNA expression was evaluated by receiver-operating characteristics (ROC), which showed high statistical significance (AUC = 0.90, p < 0.0001), thus indicating that an increased level of endometrial FUT4 mRNA may serve as a specific marker for endometriosis.

IL-22 regulates endometrial regeneration by enhancing tight junctions and orchestrating extracellular matrix

The uterine endometrium uniquely regenerates after menses, postpartum, or after breaks in the uterine layer integrity throughout women’s lives. Direct cell–cell contacts ensured by tight and adherens junctions play an important role in endometrial integrity. Any changes in these junctions can alter the endometrial permeability of the uterus and have an impact on the regeneration of uterine layers. Interleukin 22 (IL-22) is a cytokine that is recognized for its role in epithelial regeneration. Moreover, it is crucial in controlling the inflammatory response in mucosal tissues. Here, we studied the role of IL-22 in endometrial recovery after inflammation-triggered abortion. Fecundity of mice was studied in consecutive matings of the same animals after lipopolysaccharide (LPS) (10 µg per mouse)-triggered abortion. The fecundity rate after the second mating was substantially different between IL-22 knockout (IL-22^−/−) (9.1%) and wild-type (WT) (71.4%) mice (p < 0.05), while there was no difference between the groups in the initial mating, suggesting that IL-22 deficiency might be associated with secondary infertility. A considerable difference was observed between IL-22^−/− and WT mice in the uterine clearance following LPS-triggered abortion. Gross examination of the uteri of IL-22^−/− mice revealed non-viable fetuses retained inside the horns (delayed clearance). In contrast, all WT mice had completed abortion with total clearance after LPS exposure. We also discovered that IL-22 deficiency is associated with a decreased expression of tight junctions (claudin-2 and claudin-10) and cell surface pathogen protectors (mucin-1). Moreover, IL-22 has a role in the remodeling of the uterine tissue in the inflammatory environment by regulating epithelial–mesenchymal transition markers called E- and N-cadherin. Therefore, IL-22 contributes to the proper regeneration of endometrial layers after inflammation-triggered abortion. Thus, it might have a practical significance to be utilized as a treatment option postpartum (enhanced regeneration function) and in secondary infertility caused by inflammation (enhanced barrier/protector function).

Transient and Prolonged Activation of Wnt Signaling Contribute Oppositely to the Pathogenesis of Asherman's Syndrome

Asherman’s Syndrome (AS) is caused by dysfunction of endometrial regenerative ability, which is controlled by adult stem cells and their niche. The Wnt signaling pathway has been demonstrated to be implicated in this process. This study aimed to clarify the relationship between the Wnt signaling pathway and the progression of AS after initial endometrial damage. Endometria with and without adhesion as well as from the intrauterine devices three months after the surgery were collected to compare the area of fibrosis. The area% of fibrosis did not vary significantly. Significantly higher expression of non-phosphorylated β-catenin, Wnt5a and Wnt7a was identified in the endometria with adhesion. The CD140b⁺CD146⁺ endometrial stem-like cells were present in the endometria with adhesion. Both Wnt5a and Wnt7a promoted stem cell proliferation. However, only Wnt7a preserved stem cell population by stimulating self-renewal. A rat endometrial injury model was established to investigate the effect of the activated Wnt/β-catenin signaling pathway on endometrial healing. We found that a transient activation of the Wnt/β-catenin signaling pathway promoted angiogenesis and increased the number of glands. In conclusion, transient activation of the Wnt/β-catenin signaling pathway during the acute endometrial damage may help the tissue regeneration, while prolonged activation may correlate to fibrosis formation.

The pathological and therapeutic roles of mesenchymal stem cells in preeclampsia

Mesenchymal stem cells (MSCs) have made progress in the treatment of ischemic and inflammatory diseases. Preeclampsia (PE) is characterized by placenta ischemic and inflammatory injury. Our paper summarized the new role of MSCs in PE pathology and its potency in PE therapy and analyzed its current limitations. Intravenously administered MSCs dominantly distributed in perinatal tissues. There may be additional advantages to using MSCs-based therapies for reproductive disorders. It will provide new ideas for future research in this field.

IL-37 overexpression promotes endometrial regenerative cell-mediated inhibition of cardiac allograft rejection

BACKGROUND

Endometrial regenerative cells (ERCs) play an important role in attenuation of acute allograft rejection, while their effects are limited. IL-37, a newly discovered immunoregulatory cytokine of the IL-1 family, can regulate both innate and adaptive immunity. Whether IL-37 overexpression can enhance the therapeutic effects of ERCs in inhibition of acute cardiac allograft rejection remains unknown and will be explored in this study.

METHODS

C57BL/6 mice recipients receiving BALB/c mouse heterotopic heart allografts were randomly divided into the phosphate-buffered saline (untreated), ERC treated, negative lentiviral control ERC (NC-ERC) treated, and IL-37 overexpressing ERC (IL-37-ERC) treated groups. Graft pathological changes were assessed by H&E staining. The intra-graft cell infiltration and splenic immune cell populations were analyzed by immunohistochemistry and flow cytometry, respectively. The stimulatory property of recipient DCs was tested by an MLR assay. Furthermore, serum cytokine profiles of recipients were measured by ELISA assay.

RESULTS

Mice treated with IL-37-ERCs achieved significantly prolonged allograft survival compared with the ERC-treated group. Compared with all the other control groups, IL-37-ERC-treated group showed mitigated inflammatory response, a significant increase in tolerogenic dendritic cells (Tol-DCs), regulatory T cells (Tregs) in the grafts and spleens, while a reduction of Th1 and Th17 cell population. Additionally, there was a significant upregulation of immunoregulatory IL-10, while a reduction of IFN-γ, IL-17A, IL-12 was detected in the sera of IL-37-ERC-treated recipients.

CONCLUSION

IL-37 overexpression can promote the therapeutic effects of ERCs to inhibit acute allograft rejection and further prolong graft survival. This study suggests that gene-modified ERCs overexpressing IL-37 may pave the way for novel therapeutic options in the field of transplantation.

Preliminary Application of Magnetization Transfer Imaging in the Study of Normal Uterus and Uterine Lesions

Purpose

The aim of this study is to evaluate the utility of magnetization transfer (MT) imaging in the study of normal uterus and common uterine lesions.

Methods

This prospective study enrolled 160 consecutive patients with suspected uterine lesions. MT ratio (MTR) map was obtained by pelvic MT imaging on a 3.0T MRI scanner. Patients confirmed by pathology were divided into microscopic lesion group and lesion group, according to whether the maximum diameter of the lesion was less than 5 mm. After evaluating and eliminating patients with poor image quality by a three-point Likert scale, MTR values of lesions and normal endometrium, myometrium, and cervix were independently measured on the MTR map by two radiologists. Inter-reader agreement was evaluated. MTR values were compared among different uterine lesions and normal uterine structures using the Mann–Whitney U test with Bonferroni correction. Receiver operating characteristic curve was performed. The correlations between age and MTR values were explored by Pearson correlation analyses.

Results

A total of 96 patients with 121 uterine lesions in the lesion group and 41 patients in the microscopic lesion group were measured. The MTR values among normal endometrium, myometrium, and cervix were statistical significant differences (P < 0.05). There were significant differences between endometrial cancer and normal endometrium and between cervical cancer and normal cervix (both P ≤ 0.001). Area under the curve (AUC) for diagnosing endometrial and cervical cancer were 0.73 and 0.86. Myometrial lesions had significantly higher MTR values than endometrial lesions and cervical cancer (both P < 0.001), and the AUC for differentiating myometrial lesions from them were 0.89 and 0.94. MTR values of endometrial cancer were significantly higher than those of cervical cancer (P = 0.02). There was a critical correlation between age and MTR values in endometrial cancer (r = 0.81, P = 0.04).

Conclusions

MTR values showed significant differences among normal uterine structures. It was valuable for diagnosing and differentiating uterine cancer. MTR values could differentiate myometrial lesions from endometrial or cervical lesions.

Modeling Endometrium Biology and Disease

The endometrium, lining the uterine lumen, is highly essential for human reproduction. Its exceptional remodeling plasticity, including the transformation process to welcome and nest the embryo, is not well understood. Lack of representative and reliable study models allowing the molecular and cellular mechanisms underlying endometrium development and biology to be deciphered is an important hurdle to progress in the field. Recently, powerful organoid models have been developed that not only recapitulate endometrial biology such as the menstrual cycle, but also faithfully reproduce diseases of the endometrium such as endometriosis. Moreover, single-cell profiling endeavors of the endometrium in health and disease, and of derived organoids, start to provide deeper insight into cellular complexity and expression specificities, and in resulting tissue processes. This granular portrayal will not only help in understanding endometrium biology and disease, but also in pinning down the tissue’s stem cells, at present not yet conclusively defined. Here, we provide a general overview of endometrium development and biology, and the efforts of modeling both the healthy tissue, as well as its key diseased form of endometriosis. The future of modeling and deciphering this key tissue, hidden inside the womb, looks bright.

Altered differentiation of endometrial mesenchymal stromal fibroblasts is associated with endometriosis susceptibility

Cellular development is tightly regulated as mature cells with aberrant functions may initiate pathogenic processes. The endometrium is a highly regenerative tissue, shedding and regenerating each month. Endometrial stromal fibroblasts are regenerated each cycle from mesenchymal stem cells and play a pivotal role in endometriosis, a disease characterised by endometrial cells that grow outside the uterus. Why the cells of some women are more capable of developing into endometriosis lesions is not clear. Using isolated, purified and cultured endometrial cells of mesenchymal origin from 19 women with (n = 10) and without (n = 9) endometriosis we analysed the transcriptome of 33,758 individual cells and compared these to clinical characteristics and in vitro growth profiles. We show purified mesenchymal cell cultures include a mix of mesenchymal stem cells and two endometrial stromal fibroblast subtypes with distinct transcriptomic signatures indicative of varied progression through the differentiation processes. The fibroblast subgroup characterised by incomplete differentiation was predominantly (81%) derived from women with endometriosis and exhibited an altered in vitro growth profile. These results uncover an inherent difference in endometrial cells of women with endometriosis and highlight the relevance of cellular differentiation and its potential to contribute to disease susceptibility.

Comparing single cell transcriptome data to clinical characteristics and in vitro growth profiles uncovers a potential role for divergent mesenchymal-derived stromal fibroblast maturation in endometriosis susceptibility.

Unique expression patterns of the embryonal stem cell marker SOX2 and hormone receptors suggest the existence of a subpopulation of epithelial stem/progenitor cells in porcine and bovine endometrium

BACKGROUND

There are currently insufficient data on the population of endometrial epithelial stem/progenitor cells in farm animals.

OBJECTIVES

With the aim of identifying a potential population of epithelial stem/progenitor cells in the porcine and bovine endometrium, this study immunohistochemically examined the expression patterns of the oestrogen and progesterone receptors, as well as that of the embryonal stem cell marker SOX2.

METHODS

A total of 24 endometrial tissue samples obtained from cycling pigs (n = 12) and cows (n = 12) were included in our study. Each endometrium was divided into basal, middle and luminal portions. The percentage of marker-positive cells and the intensity of the immunoreaction in each portion of the endometrium were determined.

RESULTS

Inverse expression patterns of SOX2 and progesterone receptors were found in both animal species throughout the oestrous cycle. Strong diffuse SOX2 expression was detected in the basal portions of the glands, while a significant decrease in positivity and a weak immunoreaction were found in the luminal two thirds of the glandular epithelium. Strong progesterone receptor expression was observed in at least 90% of glandular cells in the middle and luminal portions, whereas weak staining and significant decrease in positivity were detected in the basal portions of the glands. One oestrogen receptor expression pattern resembled that of progesterone receptors.

CONCLUSION

The inverse expression patterns of SOX2 and hormone (especially progesterone) receptors suggest that endometrial epithelial stem/progenitor cells represent a subset of cells that reside in the basal portions of the endometrial glands in both the bovine and porcine endometrium.

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

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

circPTP4A2-miR-330-5p-PDK2 Signaling Facilitates In Vivo Survival of HuMSCs on SF-SIS Scaffolds and Improves the Repair of Damaged Endometrium

Background

Human umbilical cord mesenchymal stem cells- (HuMSCs-) based therapy has shown promising results in the treatment of intrauterine adhesions (IUA). In this study, we aimed to construct a HuMSCs-seeded silk fibroin small-intestinal submucosa (SF-SIS) scaffold and evaluate its ability to repair the damaged endometrium in an IUA mouse model.

Methods

To identify the functional effect of HuMSCs-SF-SIS scaffolds on the repair of damaged endometrium, a mouse IUA model was established. Uterine morphology and fibrosis were evaluated by hematoxylin-eosin staining and Masson staining. CircRNA sequencing, real-time PCR, and RNA fluorescence in situ hybridization were used to screen and verify the potential circRNAs involved in the repair of damaged endometrium by HuMSCs. Real-time integrated cellular measurement of oxygen consumption rate was performed using the Seahorse XF24 Extracellular Flux Analyzer. The potential downstream miRNAs and proteins of circRNAs were analyzed by dual-luciferase reporter assay and western blot.

Results

HuMSCs-SF-SIS not only increased the number of glands but also reduced the ulcer area in the IUA model. circPTP4A2 was elevated in the HuMSCs seeded on the SF-SIS scaffolds and was targeted by miR-330-5p-PDK2. It also stabilized the mitochondrial metabolism of HuMSCs. Moreover, miR-330-5p was found to inhibit PDK2 expression through the 3′ UTR target region. A rescue experiment further showed that circPTP4A2-miR-330-5p-PDK2 signaling was critical to HuMSCs-SF-SIS in decreasing the fibrosis area and increasing the number of glands in the IUA model.

Conclusion

We demonstrated that circPTP4A2 was elevated in HuMSCs-seeded on SF-SIS scaffolds and stabilized the mitochondrial metabolism through miR-330-5p-PDK2 signaling, which contributes to endometrial repair progression. These findings demonstrate that HuMSCs-seeded SF-SIS scaffolds have potential for the treatment of IUA.

Treatment of Pelvic Organ Prolapse by the Downregulation of the Expression of Mitofusin 2 in Uterosacral Ligament Tissue via Mesenchymal Stem Cells

Background: The relationship between pelvic organ prolapse (POP), an aging-related disease, and the senescence-related protein mitofusin 2 (Mfn2) has rarely been studied. The aim of the present study was to explore the therapeutic effects of the downregulation of Mfn2 expression by stem cells on POP through animal experiments. Methods: First, a rat POP model was constructed by ovariectomy and traction. The rats in the non-pelvic organ prolapse (NPOP) and POP groups were divided into four groups for negative controls (N1−N4, N1: NPOP-normal saline; N2: NPOP-untransfected stem cells; N3: NPOP-short hairpin negative control (NPOP-sh-NC); N4: NPOP-short hairpin-Mfn2 (NPOP-sh-Mfn2)), and four groups for prolapse (P1−P4, P1: POP-normal saline; P2: POP-untransfected stem cells; P3: POP-sh-NC; P4: POP-sh-Mfn2), respectively. Stem cells were then cultured and isolated. The expression of Mfn2 was inhibited by lentivirus transfection, and the stem cells were injected into the uterosacral ligament of the rats in each group. The expression levels of Mfn2 and procollagen 1A1/1A2/3A1 in the uterosacral ligaments of the rats were observed at 0, 7, 14, and 21 days after injection. Results: Compared to the rats in the NPOP group, the POP rats had significant prolapse. The Mfn2 expression in the uterosacral ligaments of the POP rats was significantly increased (p < 0.05, all), and the expression of procollagen 1A1/1A2/3A1 was significantly decreased (p < 0.001, all). The POP rat model maintained the same trend after 21 days (without stem cell injection). At day 14, compared to the rats in the N1 group, the Mfn2 expression in the uterosacral ligament of the rats in the N4 group was significantly decreased (p < 0.05, all), and the expression of procollagens was significantly increased (p < 0.05, all). Similarly, compared to the rats in the P1 group, the Mfn2 expression in the uterosacral ligament of the rats in the P4 group was significantly decreased (p < 0.05, all), and the expression of procollagens was significantly increased (p < 0.05, all). Similarly, on day 21, the Mfn2 mRNA and protein expression in the uterosacral ligament of the POP and NPOP rats was significantly decreased (p < 0.05, all), and the expression of procollagens was significantly increased (p < 0.05, all) in the rats in the sh-Mfn2 group (N4, P4) compared to the rats in the saline group (N1, P1). Conclusions: The downregulation of Mfn2 expression by stem cells decreased the expression of Mfn2 and increased the expression of procollagen1A1/1A2/3A1 in the uterosacral ligament of the POP rats; this effect was significant 14−21 days after the injection. Thus, Mfn2 may be a new target for POP control.

Exosomal AFAP1-AS1 binds to microRNA-15a-5p to promote the proliferation, migration, and invasion of ectopic endometrial stromal cells in endometriosis

BACKGROUND

Endometriosis (EMS) remains a major challenge to reproductive health due to multifactorial etiology, disease heterogeneity, and the lack of appropriate diagnostic markers and treatment. Eexosome (Exo) has become a major factor in progression of a variety of diseases. However, the mechanisms directing their role in the pathophysiology of EMS are ill-defined. Here, we aimed to investigate the clinical implications of actin filament associated protein 1-Antisense RNA 1 (AFAP1-AS1) in EMS.

METHODS

Bioinformatics analysis was used to predict the expression and interaction of AFAP1-AS1, miR-15a-5p and BCL9 in EMS, and dual luciferase reporter assay was used to verify the targeted relationship of AFAP1-AS1, miR-15a-5p, and BCL9. The Exo from endometrial stromal cells (ESCs) was isolated and characterized by transmission electron microscopy (TEM) and Nanoparticle tracking analysis (NTA). Exosome uptake studies were performed. For in vitro assay, ectopic ESCs (EcESCs) proliferation, migration, and invasion were assessed by CCK-8 and Transwell assays. In vivo assay was performed by establishment of EMS mice to validate the result derived from in vitro assay.

RESULTS

The Exo was successfully isolated from ESCs and we observed high expression of AFAP1-AS1 and BCL9 but low expression of miR-15a-5p in EMS. Moreover, Exo derived from EcESCs could deliver AFAP1-AS1 to EcESCs and thus promoting proliferation, migration, and invasion of ESCs. AFAP1-AS1 bound to BCL9, which was targeted by miR-15a-5p in EMS. In vivo experiments in nude mice revealed that inhibition of Exosomal AFAP1-AS1 suppressed migration and invasion of EcESCs through miR-15a-5p/BCL9.

CONCLUSIONS

Collectively, these findings suggested that ESCs-derived Exo carrying AFAP1-AS1 contributed to EMS pathogenesis. This study might help us realize the etiology of EMS and improve the treatment of the related complications.

Treating intrauterine adhesion using conditionally reprogrammed physiological endometrial epithelial cells

Background

There is unmet need for effective therapies of intrauterine adhesions (IUAs) that are common cause of menstrual disturbance and infertility, since current clinical procedures do not improve prognosis for patients with moderate to severe IUA, with a recurrence rate of 23–50%. Stem cell-based therapy has emerged as a therapeutic option with unsolved issues for IUA patients in the past few years. Primary endometrial epithelial cells for cell therapy are largely hampered with the extremely limited proliferation capacity of uterine epithelial cells. This study was to evaluate whether IUA is curable with conditionally reprogrammed (CR) endometrial epithelial cells.

Methods

Mouse endometrial epithelial cells (MEECs) were isolated from C57BL female mice, and long-term cultures of MEECs were established and maintained with conditional reprogramming (CR) method. DNA damage response analysis, soft agar assay, and matrigel 3D culture were carried out to determine the normal biological characteristics of CR-MEECs. The tissue-specific differentiation potential of MEECs was analyzed with air–liquid interface (ALI) 3D culture, hematoxylin and eosin (H&E) staining, Masson’s trichrome and DAB staining, immunofluorescence assay. IUA mice were constructed and transplanted with CR-MEECs. Repair and mechanisms of MEECs transplantation in IUA mice were measured with qRT-PCR, Masson’s trichrome, and DAB staining.

Results

We first successfully established long-term cultures of MEECs using CR approach. CR-MEECs maintained a rapid and stable proliferation in this co-culture system. Our data confirmed that CR-MEECs retained normal biological characteristics and endometrium tissue-specific differentiation potential. CR-MEECs also expressed estrogen and progesterone receptors and maintained the exquisite sensitivity to sex hormones in vitro. Most importantly, allogeneic transplantation of CR-MEECs successfully repaired the injured endometrium and significantly improved the pregnancy rate of IUA mice.

Conclusions

Conditionally reprogrammed physiological endometrial epithelial cells provide a novel strategy in IUA clinics in a personalized or generalized manner and also serve as a physiological model to explore biology of endometrial epithelial cells and mechanisms of IUA.

Uterine bleeding: how understanding endometrial physiology underpins menstrual health

Menstruation is a physiological process that is typically uncomplicated. However, up to one third of women globally will be affected by abnormal uterine bleeding (AUB) at some point in their reproductive years. Menstruation (that is, endometrial shedding) is a fine balance between proliferation, decidualization, inflammation, hypoxia, apoptosis, haemostasis, vasoconstriction and, finally, repair and regeneration. An imbalance in any one of these processes can lead to the abnormal endometrial phenotype of AUB. Poor menstrual health has a negative impact on a person's physical, mental, social, emotional and financial well-being. On a global scale, iron deficiency and iron deficiency anaemia are closely linked with AUB, and are often under-reported and under-recognized. The International Federation of Gynecology and Obstetrics have produced standardized terminology and a classification system for the causes of AUB. This standardization will facilitate future research endeavours, diagnosis and clinical management. In a field where no new medications have been developed for over 20 years, emerging technologies are paving the way for a deeper understanding of the biology of the endometrium in health and disease, as well as opening up novel diagnostic and management avenues.

Hypoxia Regulates the Self-Renewal of Endometrial Mesenchymal Stromal/Stem-like Cells via Notch Signaling

Human endometrium is an incredibly dynamic tissue undergoing cyclic regeneration and shedding during a woman’s reproductive life. Endometrial mesenchymal stromal/stem-like cells (eMSC) contribute to this process. A hypoxic niche with low oxygen levels has been reported in multiple somatic stem cell types. However, the knowledge of hypoxia on eMSC remains limited. In mice, stromal stem/progenitor cells can be identified by the label-retaining technique. We examined the relationship between the label-retaining stromal cells (LRSC) and hypoxia during tissue breakdown in a mouse model of simulated menses. Our results demonstrated that LRSC resided in a hypoxic microenvironment during endometrial breakdown and early repair. Immunofluorescence staining revealed that the hypoxic-located LRSC underwent proliferation and was highly colocalized with Notch1. In vitro studies illustrated that hypoxia activated Notch signaling in eMSC, leading to enhanced self-renewal, clonogenicity and proliferation of cells. More importantly, HIF-1α played an essential role in the hypoxia-mediated maintenance of eMSC through the activation of Notch signaling. In conclusion, our findings show that some endometrial stem/progenitor cells reside in a hypoxic niche during menstruation, and hypoxia can regulate the self-renewal activity of eMSC via Notch signaling.

Epigenetic Factors in Eutopic Endometrium in Women with Endometriosis and Infertility

Eutopic endometrium in patients with endometriosis is characterized by aberrant expression of essential genes during the implantation window. It predisposes to disturbance of endometrial receptivity. The pathomechanism of implantation failures in women with endometriosis remains unclear. This paper aims to summarize the knowledge on epigenetic mechanisms in eutopic endometrium in the group of patients with both endometriosis and infertility. The impaired DNA methylation patterns of gene promoter regions in eutopic tissue was established. The global profile of histone acetylation and methylation and the analysis of selected histone modifications showed significant differences in the endometrium of women with endometriosis. Aberrant expression of the proposed candidate genes may promote an unfavorable embryonic implantation environment of the endometrium due to an immunological dysfunction, inflammatory reaction, and apoptotic response in women with endometriosis. The role of the newly discovered proteins regulating gene expression, i.e., TET proteins, in endometrial pathology is not yet completely known. The cells of the eutopic endometrium in women with endometriosis contain a stable, impaired methylation pattern and a histone code. Medication targeting critical genes responsible for the aberrant gene expression pattern in eutopic endometrium may help treat infertility in women with endometriosis.