Stem cells and female reproduction

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.

Regeneration and anti-inflammatory effects of stem cells and their extracellular vesicles in gynecological diseases

There are many gynecological diseases, among which breast cancer (BC), cervical cancer (CC), endometriosis (EMs), and polycystic ovary syndrome (PCOS) are common and difficult to cure. Stem cells (SCs) are a focus of regenerative medicine. They are commonly used to treat organ damage and difficult diseases because of their potential for self-renewal and multidirectional differentiation. SCs are also commonly used for difficult-to-treat gynecological diseases because of their strong directional differentiation ability with unlimited possibilities, their tendency to adhere to the diseased tissue site, and their use as carriers for drug delivery. SCs can produce exosomes in a paracrine manner. Exosomes can be produced in large quantities and have the advantage of easy storage. Their safety and efficacy are superior to those of SCs, which have considerable potential in gynecological treatment, such as inhibiting endometrial senescence, promoting vascular reconstruction, and improving anti-inflammatory and immune functions. In this paper, we review the mechanisms of the regenerative and anti-inflammatory capacity of SCs and exosomes in incurable gynecological diseases and the current progress in their application in genetic engineering to provide a foundation for further research.

Autologous bone marrow-derived nucleated cell (aBMNC) transplantation improves endometrial function in patients with refractory Asherman's syndrome or with thin and dysfunctional endometrium

PURPOSE

The purpose was to evaluate the effect of intrauterine injection of aBMNC on the endometrial function in patients with refractory Asherman's syndrome (AS) and/or thin and dysfunctional endometrium (TE).

STUDY DESIGN

This is a prospective, experimental, non-controlled study MATERIAL AND METHODS: The study was carried out between December 2018 and December 2020 on 20 patients, who were of age < 45 years and had oligo/amenorrhea and primary infertility due to refractory AS and/or TE. One hundred ml BM was extracted. aBMNC cells were separated according to generic volume reduction protocol by using the Cell Separation System SEPAX S-100 table top centrifuge system. We have evaluated CD34+, mononuclear cell (MNC), and total nucleated cell (TNC) counts. The transplantation aBMNC was performed by two intrauterine injections at an interval of one week, transvaginally into the endometrial-myometrial junction by an ovum aspiration needle. Midcyclic endometrial thickness (ET) and gestations after transplantation were evaluated.

RESULTS

The mean TNC, MNC, and CD34+ cells were 11.55 ± 4.7 × 108, 3.85 ± 2.01 × 108, and 7.00 ± 2.88 × 106 at first injection, respectively, and 6.85 ± 2.67 × 108, 2.04 ± 1.11 × 108, and 3.44 ± 1.31 × 106 at second injection, respectively. The maximum posttransplantation ET was significantly higher than the maximum pretransplantation ET: 2.97 ± 0.48 vs. 5.76 ± 1.19 (mean ± standard deviation, p < 0.01). Twelve patients had frozen-thaw embryo transfers after the study. In 42% (n = 5 of 12) of the patients, pregnancy was achieved. One of the five patients delivered a healthy baby at term.

CONCLUSIONS

Autologous BMNC transplantation may contribute to endometrial function in patients with AS and/or TE.

Cell therapy for the treatment of reproductive diseases and infertility: an overview from the mechanism to the clinic alongside diagnostic methods

Infertility is experienced by 8%-12% of adults in their reproductive period globally and has become a prevalent concern. Besides routine therapeutic methods, stem cells are rapidly being examined as viable alternative therapies in regenerative medicine and translational investigation. Remarkable progress has been made in understanding the biology and purpose of stem cells. The affected pluripotent stem cells (iPSCs) and mesenchymal stem cells (MSCs) are further studied for their possible use in reproductive medicine, particularly for infertility induced by premature ovarian insufficiency and azoospermia. Accordingly, this study discusses current developments in the use of some kinds of MSCs such as adipose-derived stem cells, bone marrow stromal cells, umbilical cord MSCs, and menstrual blood MSCs. These methods have been used to manage ovarian and uterine disorders, and each technique presents a novel method for the therapy of infertility.

Long-term maintenance of human endometrial epithelial stem cells and their therapeutic effects on intrauterine adhesion

Background

The human endometrium is a highly regenerative tissue that is believed to have two main types of stem cells: endometrial mesenchymal/stromal stem cells (eMSCs) and endometrial epithelial stem cells (eESCs). So far, eMSCs have been extensively studied, whereas the studies of eESCs are constrained by the inability to culture and expand them in vitro. The aim of this study is to establish an efficient method for the production of eESCs from human endometrium for potential clinical application in intrauterine adhesion (IUA).

Results

Here we developed a culture condition with a combination of some small molecules for in vitro culturing and expansion of human SSEA-1⁺ cells. The SSEA-1⁺ cells exhibited stem/progenitor cell activity in vitro, including clonogenicity and differentiation capacity into endometrial epithelial cell-like cells. In addition, the SSEA-1⁺ cells, embedded in extracellular matrix, swiftly self-organized into organoid structures with long-term expansion capacity and histological phenotype of the human endometrial epithelium. Specifically, we found that the SSEA-1⁺ cells showed stronger therapeutic potential than eMSCs for IUA in vitro. In a rat model of IUA, in situ injection of the SSEA-1⁺ cells-laden chitosan could efficiently reduce fibrosis and facilitate endometrial regeneration.

Conclusions

Our work demonstrates an approach for isolation and expansion of human eESCs in vitro, and an appropriate marker, SSEA-1, to identify eESCs. Furthermore, the SSEA-1⁺ cells-laden chitosan might provide a novel cell-based approach for IUA treatment. These findings will advance the understanding of pathophysiology during endometrial restoration which may ultimately lead to more rational clinical practice.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00905-4.

Mesenchymal stem cells-derived exosomes as a promising new approach for the treatment of infertility caused by polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a multifactorial metabolic and most common endocrine disorder that its prevalence, depending on different methods of evaluating PCOS traits, varies from 4% to 21%. Chronic low-grade inflammation and irregular apoptosis of granulosa cells play a crucial role in the pathogenesis of PCOS infertility. Mesenchymal stem cells (MSCs)-derived exosomes and extracellular vesicles (EVs) are lipid bilayer complexes that act as a means of intercellular transferring of proteins, lipids, DNA and different types of RNAs. It seems that this nanoparticles have therapeutic effects on the PCOS ovary such as regulating immunity response, anti-inflammatory (local and systemic) and suppress of granulosa cells (GCs) apoptosis. Although there are few studies demonstrating the effects of exosomes on PCOS and their exact mechanisms is still unknown, in the present study we reviewed the available studies of the functions of MSC-derived exosome, EVs and secretome on apoptosis of granulosa cells and inflammation in the ovary. Therefore, the novel cell-free therapeutic approaches for PCOS were suggested in this study.

Pathogenesis of Human Adenomyosis: Current Understanding and Its Association with Infertility

The aim of this review article was to summarize our current understanding on the etiologies and pathogenesis of human adenomyosis and to clarify the relative association between adenomyosis and infertility. The exact pathogenesis of adenomyosis is still elusive. Among different reported concepts, direction invagination of gland cells from the basalis endometrium deep into myometrium is the most widely accepted opinion on the development of adenomyosis. According to this concept, endometrial epithelial cells and changed fibroblasts, abnormally found in the myometrium in response to repeated tissue injury and/or disruption at the endometrium-myometrium interface (EMI), elicit hyperplasia and hypertrophy of the surrounding smooth muscle cells. In this review, a comprehensive review was performed with a literature search using PubMed for all publications in English and Japanese (abstract in English), related to adenomyosis and infertility, from inception to April 2021. As an estrogen-regulated factor, hepatocyte growth factor (HGF) exhibits multiple functions in endometriosis, a disease commonly believed to arise from the functionalis endometrium. As a mechanistic basis of gland invagination, we investigated the role of HGF, either alone or in combination with estrogen, in the occurrence of epithelial-mesenchymal transition (EMT) in adenomyosis. Aside from microtrauma at the EMI, metaplasia of displaced Müllerian remnants, differentiation of endometrial stem/progenitor cells within the myometrium and somatic mutation of some target genes have been put forward to explain how adenomyosis develops. In addition, the possible role of microRNAs in adenomyosis is also discussed. Besides our knowledge on the conventional classification (focal and diffuse), two recently proposed classifications (intrinsic and extrinsic) of adenomyosis and the biological differences between them have been described. Although the mechanistic basis is unclear, the influence of adenomyosis on fertility outcome is important, especially considering the recent tendency to delay pregnancy among women. Besides other proposed mechanisms, a recent transmission election microscopic (TEM) study indicated that microvilli damage and an axonemal alteration in the apical endometria of human adenomyosis, in response to endometrial inflammation, may be involved in negative fertility outcomes. We present a critical analysis of the literature data concerning the mechanistic basis of infertility in women with adenomyosis and its impact on fertility outcome.

The Role of Stem Cells and Their Derived Extracellular Vesicles in Restoring Female and Male Fertility

Infertility is a globally recognized issue caused by different reproductive disorders. To date, various therapeutic approaches to restore fertility have been attempted including etiology-specific medication, hormonal therapies, surgical excisions, and assisted reproductive technologies. Although these approaches produce results, however, fertility restoration is not achieved in all cases. Advances in using stem cell (SC) therapy hold a great promise for treating infertile patients due to their abilities to self-renew, differentiate, and produce different paracrine factors to regenerate the damaged or injured cells and replenish the affected germ cells. Furthermore, SCs secrete extracellular vesicles (EVs) containing biologically active molecules including nucleic acids, lipids, and proteins. EVs are involved in various physiological and pathological processes and show promising non-cellular therapeutic uses to combat infertility. Several studies have indicated that SCs and/or their derived EVs transplantation plays a crucial role in the regeneration of different segments of the reproductive system, oocyte production, and initiation of sperm production. However, available evidence triggers the need to testify the efficacy of SC transplantation or EVs injection in resolving the infertility issues of the human population. In this review, we highlight the recent literature covering the issues of infertility in females and males, with a special focus on the possible treatments by stem cells or their derived EVs.

Therapeutic Role of Mesenchymal Stem Cell-Derived Extracellular Vesicles in Female Reproductive Diseases

Reproductive disorders, including intrauterine adhesion (IUA), premature ovarian insufficiency (POI), and polycystic ovary syndrome (PCOS), are great threats to female reproduction. Recently, mesenchymal stem cells derived-extracellular vesicles (MSC-EVs) have presented their potentials to cure these diseases, not only for the propensity ability they stemmed from the parent cells, but also for the higher biology stability and lower immunogenicity, compared to MSCs. EVs are lipid bilayer complexes, functional as mediators by transferring multiple molecules to recipient cells, such as proteins, microRNAs, lipids, and cytokines. EVs appeared to have a therapeutic effect on the female reproductive disorder, such as repairing injured endometrium, suppressing fibrosis of endometrium, regulating immunity and anti-inflammatory, and repressing apoptosis of granulosa cells (GCs) in ovaries. Although the underlying mechanisms of MSC-EVs have reached a consensus, several theories have been proposed, including promoting angiogenesis, regulating immunity, and reducing oxidate stress levels. In the current study, we summarized the current knowledge of functions of MSC-EVs on IUA, POI, and PCOS. Given the great potentials of MSC-EVs on reproductive health, the critical issues discussed will guide new insights in this rapidly expanding field.

Endometrial membrane organoids from human embryonic stem cell combined with the 3D Matrigel for endometrium regeneration in asherman syndrome

Asherman's syndrome (AS), a leading cause of uterine infertility worldwide, is characterized by scarring of the uterine surfaces lacking endometrial epithelial cells, which prevents endometrial regeneration. Current research on cell therapy for AS focuses on mesenchymal and adult stem cells from the endometrium. However, insufficient number, lack of purity, and rapid senescence of endometrial epithelial progenitor cells (EEPCs) during experimental processes restrict their use in cell therapies. In this study, we induced human embryonic stem cells-9 (H9-ESC) into EEPCs by optimizing the induction factors from the definitive endoderm. EEPCs, which act as endometrial epithelial cells, accompanied by human endometrial stromal cells provide a niche environment for the development of endometrial membrane organoids (EMOs) in an in vitro 3D culture model. To investigate the function of EMOs, we transplanted tissue-engineered constructs with EMOs into an in vivo rat AS model. The implantation of EMOs into the damaged endometrium facilitates endometrial regeneration and angiogenesis. Implanting EMOs developed from human embryonic stem cells into the endometrium might prove useful for "endometrial re-engineering" in the treatment of Asherman's syndrome.

Will stem cells from fat and growth factors from blood bring new hope to female patients with reproductive disorders?

Female reproductive system disorders (FRSD) with or without infertility are prevalent women's health problems with a variety of treatment approaches including surgery and hormone therapy. It currently considering to sub-branch of regenerative medicine including stem cells or growth factors injection-based delivery treatment might be improved female reproductive health life. The most common products used for these patients treatment are autologous cell or platelet-based products from patients, including platelet-rich plasma, plasma rich in growth factor, platelet-rich fibrin, and stromal vascular fraction. In this review, we discuss each of the above products used in treatment of FRSD and critically evaluate the clinical outcome.

Menstruation: science and society

Women's health concerns are generally underrepresented in basic and translational research, but reproductive health in particular has been hampered by a lack of understanding of basic uterine and menstrual physiology. Menstrual health is an integral part of overall health because between menarche and menopause, most women menstruate. Yet for tens of millions of women around the world, menstruation regularly and often catastrophically disrupts their physical, mental, and social well-being. Enhancing our understanding of the underlying phenomena involved in menstruation, abnormal uterine bleeding, and other menstruation-related disorders will move us closer to the goal of personalized care. Furthermore, a deeper mechanistic understanding of menstruation-a fast, scarless healing process in healthy individuals-will likely yield insights into a myriad of other diseases involving regulation of vascular function locally and systemically. We also recognize that many women now delay pregnancy and that there is an increasing desire for fertility and uterine preservation. In September 2018, the Gynecologic Health and Disease Branch of the Eunice Kennedy Shriver National Institute of Child Health and Human Development convened a 2-day meeting, "Menstruation: Science and Society" with an aim to "identify gaps and opportunities in menstruation science and to raise awareness of the need for more research in this field." Experts in fields ranging from the evolutionary role of menstruation to basic endometrial biology (including omic analysis of the endometrium, stem cells and tissue engineering of the endometrium, endometrial microbiome, and abnormal uterine bleeding and fibroids) and translational medicine (imaging and sampling modalities, patient-focused analysis of menstrual disorders including abnormal uterine bleeding, smart technologies or applications and mobile health platforms) to societal challenges in health literacy and dissemination frameworks across different economic and cultural landscapes shared current state-of-the-art and future vision, incorporating the patient voice at the launch of the meeting. Here, we provide an enhanced meeting report with extensive up-to-date (as of submission) context, capturing the spectrum from how the basic processes of menstruation commence in response to progesterone withdrawal, through the role of tissue-resident and circulating stem and progenitor cells in monthly regeneration-and current gaps in knowledge on how dysregulation leads to abnormal uterine bleeding and other menstruation-related disorders such as adenomyosis, endometriosis, and fibroids-to the clinical challenges in diagnostics, treatment, and patient and societal education. We conclude with an overview of how the global agenda concerning menstruation, and specifically menstrual health and hygiene, are gaining momentum, ranging from increasing investment in addressing menstruation-related barriers facing girls in schools in low- to middle-income countries to the more recent "menstrual equity" and "period poverty" movements spreading across high-income countries.

Application of adipose-derived, muscle-derived, and co-cultured stem cells for the treatment of stress urinary incontinence in rat models

OBJECTIVES

Based on the recent advancements in cell therapy techniques, we aimed to evaluate the efficacy of transurethral injection of autologous adipose-derived stem cells, muscle-derived stem cells, and co-cultured cells for the rehabilitation of stress urinary incontinence rat models. We hypothesized that the utilization of co-cultured stem cells could result in enhanced therapeutic outcomes attributed to their more comprehensive environment of paracrine factors and cytokines.

METHODS

We performed bilateral pudendal nerve transection surgeries to simulate urinary incontinence in 25 female Wistar rats and employed urodynamic evaluations to confirm the injury. We autologously isolated and cultured adipose-derived mesenchymal stem cells, muscle-derived stem cells, and a mixed culture of the two types, which we subsequently injected into the urethral lumen of the damaged animals. Three weeks after the injection, urodynamic assays, histological staining, and immunohistochemical evaluations were performed to determine the efficacy of the implanted cell cultures in sphincter function improvements or structural modifications.

RESULTS

Histological evaluations suggested a regenerative process in the muscular layer of the external sphincter 3 weeks after the injection. Also, immunohistochemical analysis revealed a thickened periurethral striated muscle layer in the co-cultured group. Postinjection urodynamic analysis indicated that the urethral pressure profile significantly increased in the co-cultured group compared with other groups.

CONCLUSIONS

The outcomes of this investigation indicated that the application of co-cultured adipose-derived and muscle-derived stem cells could be associated with higher therapeutic value in stress urinary incontinence patients compared with singular-cell treatments.

Uterine Cells Improved Ovarian Function in a Murine Model of Ovarian Insufficiency

Primary ovarian insufficiency (POI) is defined as ovarian dysfunction in women younger than 40 years. It affects 1% of the women in this age-group and can occur iatrogenically after chemotherapy. Stem cells have been used in attempt to restore ovarian function in POI. In particular, endometrial mesenchymal stem cells (eMSCs) are easily obtainable in humans and have shown great potential for regenerative medicine. Here, we studied the potential for uterine cell (UC) suspensions containing eMSCs to improve ovarian function in a murine model of chemotherapy-induced POI. Green fluorescent protein (GFP)-labeled UC or phosphate-buffered solution (PBS) was delivered intravenously after chemotherapy. There was a significant increase in oocytes production and serum anti-Müllerian hormone concentrations after 6 weeks, as well as a 19% higher body mass in UC-treated mice. Similarly, we observed an increased number of pups in mice treated with UC than in mice treated with PBS. None of the oocytes or pups incorporated GFP, suggesting that there was no contribution of these stem cells to the oocyte pool. We conclude that treatment with UC indirectly improved ovarian function in mice with chemotherapy-induced POI. Furthermore, our study suggests that endometrial stem cell therapy may be beneficial to young women who undergo ovotoxic chemotherapy.

Management of uterine adenomyosis: current trends and uterine artery embolization as a potential alternative to hysterectomy

Adenomyosis is a challenging clinical condition that is commonly being diagnosed in women of reproductive age. To date, many aspects of the disease have not been fully understood, making management increasingly difficult. Over time, minimally invasive diagnostic and treatment methods have developed as more women desire uterine preservation for future fertility or to avoid major surgery. Several uterine-sparing treatment options are now available, including medication, hysteroscopic resection or ablation, conservative surgical methods, and high-intensity focused ultrasound each with its own risks and benefits. Uterine artery embolization is an established treatment option for uterine fibroids and has recently gained ground as a safe and cost-effective method for treatment of uterine adenomyosis with promising results. In this review, we discuss current trends in the management of uterine adenomyosis with a special focus on uterine artery embolization as an alternative to hysterectomy.

Stem cells on regenerative and reproductive science in domestic animals

Stem cells are undifferentiated and self-renewable cells that present new possibilities for both regenerative medicine and the understanding of early mammalian development. Adult multipotent stem cells are already widely used worldwide in human and veterinary medicine, and their therapeutic signalling, particularly with respect to immunomodulation, and their trophic properties have been intensively studied. The derivation of embryonic stem cells (ESCs) from domestic species, however, has been challenging, and the poor results do not reflect the successes obtained in mouse and human experiments. More recently, the generation of induced pluripotent stem cells (iPSCs) via the forced expression of specific transcription factors has been demonstrated in domestic species and has introduced new potentials in regenerative medicine and reproductive science based upon the ability of these cells to differentiate into a variety of cells types in vitro. For example, iPSCs have been differentiated into primordial germ-like cells (PGC-like cells, PGCLs) and functional gametes in mice. The possibility of using iPSCs from domestic species for this purpose would contribute significantly to reproductive technologies, offering unprecedented opportunities to restore fertility, to preserve endangered species and to generate transgenic animals for biomedical applications. Therefore, this review aims to provide an updated overview of adult multipotent stem cells and to discuss new possibilities introduced by the generation of iPSCs in domestic animals, highlighting the possibility of generating gametes in vitro via PGCL induction.

Research advances in the regulation of the putative ovarian germline stem cell niche on female germline stem cells

Stem cells are ideal seeding cells, which have the potential for self-renewal and multiple differentiation, and they play a fundamental role in maintaining homeostasis and regenerating and repairing tissue. The discovery of female germline stem cells (FGSCs) brings much hope for the postnatal renewal of oocytes and solving some female infertility problems. Ovarian function declines with increasing female age. Moreover, ovarian germline stem cell niche-aging could be the main cause of ovarian senescence, which ultimately leads to decreased follicle generation, declining female fertility, and age-related diseases, such as osteoporosis and ovarian cancer. The ovarian germline stem cell niche is the surrounding microenvironment in which FGSCs live, and it helps control the biological characteristics of FGSCs in many ways, such as nutritional supply and immunological cytokine secretion. This paper reviews the knowledge about the ovarian germline stem cell niche and its probable regulatory mechanisms on FGSCs, which provides valuable scientific information and scope for the prevention and treatment of ovarian senescence. Abbreviations: BMP: bone morphogenetic protein; Dpp: decapentaplegic; FGSC: female germline stem cell; IL, interleukin; OGSC: ovarian germline stem cells; ROS: reactive oxygen species; TGF, transforming growth factor; TNF, tumor necrosis factor.

Effects of endometrial stem cell transplantation combined with estrogen in the repair of endometrial injury

The present study investigated the effects of endometrial stem cell (EnSCs) transplantation combined with estrogen in the repair of endometrial injury. A total of 30 patients with intrauterine adhesions (IUA) and 30 healthy individuals were selected. Expression of epidermal growth factor (EGF) and platelet-derived growth factor (PDGF)-BB in endometrial tissue was assessed. Additionally, expression levels of epithelial membrane antigen (EMA), cytokeratin (CK), integrin α-6 (CD49f), Thy-1 membrane glycoprotein (THY-1), collagen type 1 (Col I), fibroblast (5B5) and vimentin in EnSCs were detected using western blot analysis and reverse transcription-quantitative polymerase chain reaction. A rat model of IUA was established and female rats were divided into the control, model, EnSCs, estrogen and estrogen plus EnSCs (E+EnSCs) groups. Blood was extracted at 1 and 5 weeks post-treatment, and serum levels of transforming growth factor (TGF)-β1, EGF, 17 β-estradiol (E2) and PDGF-BB were measured using ELISA. Hematoxylin and eosin staining was performed to observe the pathological changes of endometrial tissue in rats. Western blot analysis was used to detect the expression of estrogen receptor (ESR1) and matrix metalloproteinase (MMP)-9 in the endometrium. The results revealed that patients with IUA exhibited increased expression levels of EGF and PDGF-BB compared with those in control group. Additionally, EnSCs exhibited significantly increased expression levels of EMA, CD49f, CK, Col I, THY-1, 5B5 and vimentin compared with the remaining groups. An increased number of newly formed glands was observed in the E+EnSCs group compared with that in the EnSCs group. Increased levels of E2, but decreased levels of TGF-β1, EGF, PDGF-BB, ESR1 and MMP-9 were detected in EnSCs and estrogen groups compared with those in E+EnSCs group. These results suggest that EnSCs transplantation combined with estrogen could improve endometrial abnormalities.

Unravelling the biological secrets of microchimerism by single-cell analysis

The presence of microchimeric cells is known for >100 years and well documented since decades. Earlier, microchimeric cells were mainly used for cell-based non-invasive prenatal diagnostics during early pregnancy. Microchimeric cells are also present beyond delivery and are associated to various autoimmune diseases, tissue repair, cancer and immune tolerance. All these findings were based on low complexity studies and occasionally accompanied by artefacts not allowing the biological functions of microchimerism to be determined. However, with the recent developments in single-cell analysis, new means to identify and characterize microchimeric cells are available. Cell labelling techniques in combination with single-cell analysis provide a new toolbox to decipher the biology of microchimeric cells at molecular and cellular level. In this review, we discuss how recent developments in single-cell analysis can be applied to determine the role and function of microchimeric cells.

Bone Marrow Stem Cells Do Not Contribute to Endometrial Cell Lineages in Chimeric Mouse Models

Studies from five independent laboratories conclude that bone marrow stem cells transdifferentiate into endometrial stroma, epithelium, and endothelium. We investigated the nature of bone marrow-derived cells in the mouse endometrium by reconstituting irradiated wild type recipients with bone marrow containing transgenic mTert-green fluorescent protein (GFP) or chicken β-actin (Ch β-actin)-GFP reporters. mTert-GFP is a telomerase marker identifying hematopoietic stem cells and subpopulations of epithelial, endothelial, and immune cells in the endometrium. Ch β-actin-GFP is a ubiquitous reporter previously used to identify bone marrow-derived cells in the endometrium. Confocal fluorescence microscopy for GFP and markers of endometrial and immune cells were used to characterize bone marrow-derived cells in the endometrium of transplant recipients. No evidence of GFP⁺ bone marrow-derived stroma, epithelium, or endothelium was observed in the endometrium of mTert-GFP or Ch β-actin-GFP recipients. All GFP⁺ cells detected in the endometrium were immune cells expressing the pan leukocyte marker CD45, including CD3⁺ T cells and F4/80⁺ macrophages. Further examination of the Ch β-actin-GFP transplant model revealed that bone marrow-derived F4/80⁺ macrophages immunostained weakly for CD45. These macrophages were abundant in the stroma, infiltrated the epithelial and vascular compartments, and could easily be mistaken for bone marrow-derived endometrial cells. We conclude that it is unlikely that bone marrow cells are able to transdifferentiate into endometrial stroma, epithelium, and endothelium. This result has important therapeutic implications, as the expectation that bone marrow stem cells contribute directly to endometrial regeneration is shaping strategies designed to regenerate endometrium in Asherman's syndrome and to control aberrant endometrial growth in endometriosis. Stem Cells 2018;36:91-102.

Stem Cell Markers Describe a Transition From Somatic to Pluripotent Cell States in a Rat Model of Endometriosis

OBJECTIVE

To study Thy1 as a fibroblast marker, SSEA1 as a marker of intermediate pluripotency, and Oct4 as a marker of established pluripotency in rat model of endometriosis.

DESIGN

In vivo animal study.

MATERIALS AND METHODS

Endometriosis was induced in 20 albino female rats through autologous transplantation of one uterine horn to mesentery of intestine. Other 20 rats had their horn removed without transplantation (controls). Rats were sacrificed 4 weeks after induction surgery. Ectopic, eutopic, and control endometria were harvested from endometriosis and control animals respectively. Quantitative syber green based RT-PCR was used to detect expression of Thy-1 (CD90), FUT4 (SSEA1), and POU5F1 (Oct4) genes in tissues. Relative expression was normalized to that of β actin. Thy1, SSEA1, and Oct4 protein expression were detected by immunohistochemistry.

RESULTS

Ectopic endometrium expressed significantly higher mRNA of Oct4 and SSEA1 as compared to control endometrium. Expression levels of Oct4 and SSEA1 were comparable between ectopic and eutopic endometria and between eutopic and control endometria. Thy1 (CD90) gene expression level was comparable among ectopic, eutopic, and control endometria. Oct4 immunoscore were significantly higher in ectopic (6.6±0.91) than eutopic (2.5±0.78) or control endometrium (3.7±0.1) (P value 0.02). Thy1 and SSEA1 immunoscores were comparable among all three types of endometria.

CONCLUSIONS

Using rat model of endometriosis, ectopic endometrium showed significantly higher Oct4, and SSEA1, but similar Thy1 gene expression to that of control endometrium. This indicates increased transition from somatic to pluripotent cell states in ectopic endometrium which may play a role in endometriosis pathogenesis.

CXCL12 Promotes Stem Cell Recruitment and Uterine Repair after Injury in Asherman's Syndrome

Asherman’s syndrome is an acquired condition of uterine fibrosis and adhesions in response to injury that adversely affects fertility and pregnancy. We have previously demonstrated that bone marrow-derived mesenchymal stem cells (BMDSCs) contribute to uterine repair after injury and that stem cells supplementation improves fertility. Here, we demonstrate that CXCL12 is the chemokine that mediates stem cell engraftment and functional improvement using a murine model of Asherman’s syndrome. After uterine injury, we demonstrate that CXCL12 augmentation increased BMDSC engraftment and that the CXCL12 receptor (CXCR4) antagonist, ADM3100, blocked stem cell recruitment. CXCL12 reduced, whereas ADM3100 increased fibrosis. CXCL12 treatment led to improved fertility and litter size, whereas ADM3100 treatment reduced fertility and litter size. ADM3100 prevented optimal spontaneous uterine repair mediated by endogenous CXCL12 production, reducing pregnancies after injury in the absence of supplemental CXCL12 administration; however, ADM3100 treatment could be partially rescued by CXCL12 augmentation. CXCL12 or other CXCR4 receptor agonists may be useful in the treatment of infertility or adverse pregnancy outcomes in Asherman’s syndrome and other related uterine disorders.

Bone Marrow Stem Cell Chemotactic Activity Is Induced by Elevated CXCl12 in Endometriosis

Endometriosis is an inflammatory gynecological disorder caused by the growth of endometrial tissue outside the uterus. Endometriosis produces chemokines, including CXCL12, that attract bone marrow cells to the lesions. In this study, we describe the expression, localization, and chemotactic activity of CXCL12 in endometriotic lesions. Biopsies were collected both from women with endometriosis undergoing laparoscopy and control endometrium from women without endometriosis. Expression of CXCl12 and CXCR4 messenger RNA was increased approximately 4- and 6-fold, respectively, in endometriosis compared to eutopic endometrium. Immunohistochemistry of lesions revealed that CXCR4 was expressed in the stroma and epithelium in both endometriosis and control eutopic endometrium. The level of CXCR4 protein expression was significantly higher in all cellular compartments of the endometriotic lesions compared to control endometrium. CXCL12 protein expression was also higher in endometriotic lesions and was greatest in the epithelial compartment. CXCL12 was increased more in the condition media of cultured endometriosis than in controls as measured by enzyme-linked immunosorbent assay. Transwell chamber migration was used to demonstrate 2-fold increased chemoattraction of mouse bone marrow stem cells toward CXCL12 in the endometriotic-conditioned medium compared with eutopic endometrium. Our results indicate that a preferential recruitment of stem cells to endometriosis can explain how endometriosis outcompetes eutopic endometrium in recruiting the limited supply of circulating stem cells. The CXCL12/CXCR4 signaling axis is a potential target for the treatment of endometriosis and its associated disorders.

The effect of steroid hormones on the mRNA expression of oct4 and sox2 in uterine tissue of the ovariectomized mice model of menopause

BACKGROUND

The uterus is a dynamic tissue responding to hormonal changes during reproductive cycles. As such, uterine stem cells have been studied in recent years. Transcription factors oct4 and sox2 are critical for effective maintenance of pluripotent cell identity.

OBJECTIVE

The present research evaluated the mRNA expression of oct4 and sox2 in the uterine tissues of ovariectomized mice treated with steroid hormones.

MATERIALS AND METHODS

In this experimental study, adult virgin female mice were ovariectomized and treated with estradiol 17β (E2), progesterone (P4), and a combination of E2 and P4 (E2 & P4) for 5 days. Uterine tissues were removed, and immunofluorescent (IF) staining and quantitative real-time PCR of oct4 and sox2 markers were performed.

RESULTS

IF showed oct4 and sox2 expression in the uterine endometrium and myometrium among all groups. The mRNA expression of oct4 (p=0.022) and sox2 (p=0.042) in the E2-treated group significantly were decreased compared to that in the control group. By contrast, the mRNA expression of oct4 and sox2 in the P4 (p=0.641 and 0.489 respectively) and E2 & P4-treated groups (p=0.267 and 0.264 respectively) did not show significant differences compared to the control group.

CONCLUSION

The results indicate ovarian steroid hormones change the expression of oct4 and sox2 in the mice uterine tissues, which suggest the involvement of steroid hormonal regulation in uterine stem cells.

Expression of stem cell-related genes in the endometrium and endometriotic lesions: a pilot study

OBJECTIVE

To compare the expression of stem cell-related genes in the endometrium (END), superficial endometriosis (SE), and deep infiltrating endometriosis (DIE).

STUDY DESIGN

We performed a prospective pilot study of six women suffering from SE and DIE who gave consent for laparoscopy surgery, endometrial biopsies, and participation in this study. Quantitative RT-PCR analysis of 84 stem cell-related genes was performed in 18 biopsy samples.

RESULTS

A total of 40 of 84 genes were expressed in SE and DIE, but were different from END as follows. Seven genes were over-expressed in SE and 33 genes were under-expressed in DIE compared with END. Two genes were only over-expressed in SE and three genes were only over-expressed in DIE. Six under-expressed genes were exclusively located in SE and one was only located in DIE. The remaining 31 genes were not different among the groups. There was no significant difference in gene expression between SE and DIE samples.

CONCLUSION

Tissue of DIE and SE appears to have similar stem cell-related genes. Nevertheless, there are differences in gene expression between SE and DIE.

Expression of pluripotent stem cell markers in mouse uterine tissue during estrous cycle

It was assumed that uterine stem cells are responsible for the unique regenerative capacity of uterine. Therefore, the aim of the present study was to investigate the expression of the pluripotent stem cell markers in the mice uterine tissue during different stages of estrous cycles. Twelve virgin female NMRI mice (6 to 8 weeks old) were considered at proestrus, estrus, metestrus and diestrus according to the cell types observed in the vaginal smear and underwent hysterectomy operation. Quantitative real-time polymerase chain reaction (PCR) and immunohistochemical staining for pluripotent stem cell markers (SOX2, OCT4, KLF4, and NANOG) were performed. Immunofluorescence staining revealed that expression and localization of the pluripotency markers SOX2, OCT4, KLF4, and NANOG at the protein level were not different throughout estrous cycle. Also, mRNA of pluripotency markers was detected in all tested samples. However, there were no significant differences in their genes expression at each stage and during the estrous cycle. Different hormonal profile during the estrous cycle could not affect expression of pluripotent stem cell markers in uterine tissue.

Endometrial stem/progenitor cells: the first 10 years

BACKGROUND

The existence of stem/progenitor cells in the endometrium was postulated many years ago, but the first functional evidence was only published in 2004. The identification of rare epithelial and stromal populations of clonogenic cells in human endometrium has opened an active area of research on endometrial stem/progenitor cells in the subsequent 10 years.

METHODS

The published literature was searched using the PubMed database with the search terms ‘endometrial stem cells and menstrual blood stem cells' until December 2014.

RESULTS

Endometrial epithelial stem/progenitor cells have been identified as clonogenic cells in human and as label-retaining or CD44⁺ cells in mouse endometrium, but their characterization has been modest. In contrast, endometrial mesenchymal stem/stromal cells (MSCs) have been well characterized and show similar properties to bone marrow MSCs. Specific markers for their enrichment have been identified, CD146⁺PDGFRβ⁺ (platelet-derived growth factor receptor beta) and SUSD2⁺ (sushi domain containing-2), which detected their perivascular location and likely pericyte identity in endometrial basalis and functionalis vessels. Transcriptomics and secretomics of SUSD2⁺ cells confirm their perivascular phenotype. Stromal fibroblasts cultured from endometrial tissue or menstrual blood also have some MSC characteristics and demonstrate broad multilineage differentiation potential for mesodermal, endodermal and ectodermal lineages, indicating their plasticity. Side population (SP) cells are a mixed population, although predominantly vascular cells, which exhibit adult stem cell properties, including tissue reconstitution. There is some evidence that bone marrow cells contribute a small population of endometrial epithelial and stromal cells. The discovery of specific markers for endometrial stem/progenitor cells has enabled the examination of their role in endometrial proliferative disorders, including endometriosis, adenomyosis and Asherman's syndrome. Endometrial MSCs (eMSCs) and menstrual blood stromal fibroblasts are an attractive source of MSCs for regenerative medicine because of their relative ease of acquisition with minimal morbidity. Their homologous and non-homologous use as autologous and allogeneic cells for therapeutic purposes is currently being assessed in preclinical animal models of pelvic organ prolapse and phase I/II clinical trials for cardiac failure. eMSCs and stromal fibroblasts also exhibit non-stem cell-associated immunomodulatory and anti-inflammatory properties, further emphasizing their desirable properties for cell-based therapies.

CONCLUSIONS

Much has been learnt about endometrial stem/progenitor cells in the 10 years since their discovery, although several unresolved issues remain. These include rationalizing the terminology and diagnostic characteristics used for distinguishing perivascular stem/progenitor cells from stromal fibroblasts, which also have considerable differentiation potential. The hierarchical relationship between clonogenic epithelial progenitor cells, endometrial and decidual SP cells, CD146⁺PDGFR-β⁺ and SUSD2⁺ cells and menstrual blood stromal fibroblasts still needs to be resolved. Developing more genetic animal models for investigating the role of endometrial stem/progenitor cells in endometrial disorders is required, as well as elucidating which bone marrow cells contribute to endometrial tissue. Deep sequencing and epigenetic profiling of enriched populations of endometrial stem/progenitor cells and their differentiated progeny at the population and single-cell level will shed new light on the regulation and function of endometrial stem/progenitor cells.

The Role of Stem Cells in the Etiology and Pathophysiology of Endometriosis

Human endometrium is a dynamic organ that normally undergoes repetitive cyclic regeneration. To enable this rapid regeneration, it is not surprising that the endometrium contains a reservoir of progenitor stem cells. However, this pool of cells that allows the growth of the endometrium also allows for unrestrained growth that can reach beyond the endometrium. In this review, we will address the role of stem cells in endometriosis. Recent characterization of stem cell populations within human endometrium has opened the possibility of understanding their physiologic as well as their pathologic roles. While stem cells are critical to the cyclic regeneration of a healthy endometrium, we have shown that both endometrium-derived and bone marrow-derived stem cells can migrate to ectopic sites and contribute to the development of endometriosis. Furthermore, endometriosis interferes with the normal stem cell trafficking to the uterus that is necessary for endometrial growth and repair. Altered stem cell mobility and engraftment characterize this disease.

The Role of Stem Cells in the Etiology and Pathophysiology of Endometriosis

Human endometrium is a dynamic organ that normally undergoes repetitive cyclic regeneration. To enable this rapid regeneration, it is not surprising that the endometrium contains a reservoir of progenitor stem cells. However, this pool of cells that allows the growth of the endometrium also allows for unrestrained growth that can reach beyond the endometrium. In this review, we will address the role of stem cells in endometriosis. Recent characterization of stem cell populations within human endometrium has opened the possibility of understanding their physiologic as well as their pathologic roles. While stem cells are critical to the cyclic regeneration of a healthy endometrium, we have shown that both endometrium-derived and bone marrow-derived stem cells can migrate to ectopic sites and contribute to the development of endometriosis. Furthermore, endometriosis interferes with the normal stem cell trafficking to the uterus that is necessary for endometrial growth and repair. Altered stem cell mobility and engraftment characterize this disease.

Identification of pluripotent cells in bovine uterus: in situ and in vitro studies

The aim of this study was to identify uterine pluripotent cells both in bovine uterine tissues as well in epithelial, stromal, and myometrial uterine cell populations. Moreover, the relationship of pluripotent markers expression with age and the uterine horn side was considered. Uterine tissue was collected from ipsilateral and contralateral horns (days 8–10 of the estrous cycle). Immunohistostaining for C-KIT, OCT3/4, NANOG, and SOX2 in uterine tissue was determined. mRNA expression of C-KIT, OCT3/4, NANOG and SOX2 was evaluated in uterine tissue relative to the age of the cow and uterine horn side. Gene and protein expression of these markers in the uterine luminal epithelial, stromal, and myometrial cells was evaluated by real-time PCR and western blotting respectively. The expression of pluripotent cell markers OCT3/4, NANOG, and SOX2 was identified by flow cytometry assay in epithelial, stromal, and myometrial cells. Multilineage differentiation of the bovine uterine cells was performed. mRNA expression of OCT3/4, NANOG, and SOX2 in uterine tissue was higher in the ipsilateral horn than in the contralateral horn. Flow cytometry assay revealed positive fluorescence for OCT3/4, NANOG, and SOX2 in all uterine cell types. Results showed the age-dependent expression of pluripotent markers in uterine tissue. Beside, the different expression of pluripotent cells in each horn of uterus suggests the influence of ovarian hormones on these characteristics. The highest mRNA and protein expression for pluripotent markers was observed in stromal cells among uterine cells, which indicates this population of cells as the main site of pluripotent cells in the cow uterus.

Somatic stem cells and their dysfunction in endometriosis

Emerging evidence indicates that somatic stem cells (SSCs) of different types prominently contribute to endometrium-associated disorders such as endometriosis. We reviewed the pertinent studies available on PubMed, published in English language until December 2014 and focused on the involvement of SSCs in the pathogenesis of this common gynecological disease. A concise summary of the data obtained from in vitro experiments, animal models, and human tissue analyses provides insights into the SSC dysregulation in endometriotic lesions. In addition, a set of research results is presented supporting that SSC-targeting, in combination with hormonal therapy, may result in improved control of the disease, while a more in-depth characterization of endometriosis SSCs may contribute to the development of early-disease diagnostic tests with increased sensitivity and specificity. Key message: Seemingly essential for the establishment and progression of endometriotic lesions, dysregulated SSCs, and associated molecular alterations hold a promise as potential endometriosis markers and therapeutic targets.

Targeting the Wnt/β-catenin pathway in endometriosis: a potentially effective approach for treatment and prevention

Endometriosis is a chronic, estrogen-dependent disease associated with infertility and pelvic pain. Endometriosis is defined by the presence of extra-uterine endometrial tissue. It affects approximately 10% of reproductive-aged women. However, the underlying etiology, pathogenesis and pathophysiology remain to be fully elucidated. Knowledge of these factors is indispensable for the development of targeted therapies for prevention and treatment of endometriosis. Several studies, including those from our laboratory, have suggested that aberrant activation of the Wnt/β-catenin pathway may be involved in the pathophysiology of endometriosis. This is a review of the literature focused on the aberrant activation of the Wnt/β-catenin pathway in patients with endometriosis, and on how targeting the Wnt/targeting pathway may be a potentially effective approach for treating and/or preventing endometriosis.

Targeting the Wnt/β-catenin pathway in endometriosis: a potentially effective approach for treatment and prevention

Endometriosis is a chronic, estrogen-dependent disease associated with infertility and pelvic pain. Endometriosis is defined by the presence of extra-uterine endometrial tissue. It affects approximately 10% of reproductive-aged women. However, the underlying etiology, pathogenesis and pathophysiology remain to be fully elucidated. Knowledge of these factors is indispensable for the development of targeted therapies for prevention and treatment of endometriosis. Several studies, including those from our laboratory, have suggested that aberrant activation of the Wnt/β-catenin pathway may be involved in the pathophysiology of endometriosis. This is a review of the literature focused on the aberrant activation of the Wnt/β-catenin pathway in patients with endometriosis, and on how targeting the Wnt/targeting pathway may be a potentially effective approach for treating and/or preventing endometriosis.

Endometrial stem cells in regenerative medicine

First described in 2004, endometrial stem cells (EnSCs) are adult stem cells isolated from the endometrial tissue. EnSCs comprise of a population of epithelial stem cells, mesenchymal stem cells, and side population stem cells. When secreted in the menstrual blood, they are termed menstrual stem cells or endometrial regenerative cells. Mounting evidence suggests that EnSCs can be utilized in regenerative medicine. EnSCs can be used as immuno-modulatory agents to attenuate inflammation, are implicated in angiogenesis and vascularization during tissue regeneration, and can also be reprogrammed into induced pluripotent stem cells. Furthermore, EnSCs can be used in tissue engineering applications and there are several clinical trials currently in place to ascertain the therapeutic potential of EnSCs. This review highlights the progress made in EnSC research, describing their mesodermal, ectodermal, and endodermal potentials both in vitro and in vivo.

Isolation and identification of epithelial and stromal stem cells from eutopic endometrium of women with endometriosis

OBJECTIVE

The recent characterization of possible stem/progenitor cells in the endometrium has shed new light on the origins of ectopic endometrial tissue and the mechanism for the pathogenesis of endometriosis, but has raised new questions. Is it possible that abnormal endometrial stem/progenitor cells increase their capacity to implant and establish themselves as ectopic tissue, or that normal stem cells implant in abnormal peritoneum? This study investigated key stem cell properties in cologenic epithelial and stromal cells obtained from eutopic endometrium of women with endometriosis.

STUDY DESIGN

Single cell suspensions of endometrial epithelial and stromal cells were cultured at densities of 20, 50, 100 and 200cells/cm(2). Cloning efficiency (CE) was determined, and stem cell phenotypic surface markers were detected using Western blotting and quantitative real-time polymerase chain reaction.

RESULTS

CE was significantly higher in cells cultured at a density of 50cells/cm(2) compared with the other groups. After 15 days of culture, small and large colonies were observed. Large-colony-derived epithelial and stromal cells had high proliferative potentials, producing millions of cells in vitro, with strong expression of epithelial and stromal stem cell phenotypic surface markers EMA, CK, CD49f, THY-1(CD90), collagen type I, 5B5 and vimentin.

CONCLUSION

Adult stem cells were found in eutopic endometrium of women with endometriosis, and this may play an important role in disease development.

Theories on the pathogenesis of endometriosis

Endometriosis is a common, chronic inflammatory disease defined by the presence of extrauterine endometrial tissue. The aetiology of endometriosis is complex and multifactorial, where several not fully confirmed theories describe its pathogenesis. This review examines existing theories on the initiation and propagation of different types of endometriotic lesions, as well as critically appraises the myriad of biologically relevant evidence that support or oppose each of the proposed theories. The current literature suggests that stem cells, dysfunctional immune response, genetic predisposition, and aberrant peritoneal environment may all be involved in the establishment and propagation of endometriotic lesions. An orchestrated scientific and clinical effort is needed to consider all factors involved in the pathogenesis of this multifaceted disease and to propose novel therapeutic targets to reach effective treatments for this distressing condition.

Atypical Expression of COX-2, StAR, CYP19A1 and Apoptotic Regulators in CD90 Positive Endometrial Stromal Cells from Women with Endometriosis

Purpose

Endometriosis is an invasive gynecologic disease characterized by diminished apoptosis, sustained ectopic survival of dysfunctional endometrial cells and implantation of endometriotic lesions outside of the uterus. The purpose of this investigation was to determine the expression pattern of apoptotic and steroidogenic genes in the progenitor stem cell population of eutopic tissues from women with endometriosis and compare them to controls. The expression of these genes was determined in a subpopulation of endometrial cells that displayed CD90 positivity (CD+ve90) and colony forming capacity.

Methods

We obtained endometrial samples from women with or without endometriosis. Endometrial stromal cells (ESCs) were isolated and cultured for 15 days. Purified ESCs were sorted by using a multipotent mesenchymal stromal cell multi-color flow cytometry kit. Single cell cloning was performed by serial dilution in 96-micro well plates. Fifteen days later, colonies were identified (CFUs). The colonies were chosen and cultured. mRNA expression of apoptotic genes, mitogen activated kinase 14 (MAPK14), nuclear factor kappa B (NFkB), steroidogenic acute regulatory protein (StAR), aromatase (CYP19A1) and cyclo-oxygenase-2 (COX-2) were determined by qRT-PCR. Protein levels of StAR, CYP19A1 and COX-2 were determined by western blotting.

Results

A subset of stromal cells derived from women with endometriosis were isolated and identified as progenitor stem cells based on their CD90 positivity and colony forming ability. The cells displayed increased levels of MAPK14, NFkB, COX-2, StAR and CYP19A1 both at the mRNA and protein level compared to stromal cells derived from controls. Similarly, pro-apoptotic molecules such as Bax were decreased whereas anti-apoptotic molecules such as Bcl2 were decreased at the mRNA level compared to stromal cells derived from controls.

Conclusions

CD90+ve ESCs derived from women with endometriosis displayed markers suggesting stem cell-like properties and aberrant expression of apoptotic and steroidogenic enzymes which may contribute to sustained survival of these cells.

Reproductive stem cell differentiation: extracellular matrix, tissue microenvironment, and growth factors direct the mesenchymal stem cell lineage commitment

The mesenchymal stem cells (MSCs) have awakened interest in regenerative medicine due to its high capability to proliferate and differentiate in multiple specialized lineages under defined conditions. The reproductive system is considered a valuable source of MSCs, which needs further investigations. Many factors have been reported as critical for these cell lineage specification and determination. In this review, we discuss the main effects of extracellular matrix or tissue environment and growth factors in the cell lineage commitment, including the reproductive stem cells. The MSCs responses to culture medium stimuli or to soluble factors probably occur through several intracellular activation pathways. However, the molecular mechanisms in which the cells respond to these mechanical or chemical perturbations remain elusive. Recent findings suggest a synergic effect of microenvironment and soluble cell culture factors affecting cell differentiation. For future applications in cell therapy, protocols of reproductive MSCs differentiation must be established.

Bone marrow-derived cells from male donors do not contribute to the endometrial side population of the recipient

Accumulated evidence demonstrates the existence of bone marrow-derived cells origin in the endometria of women undergoing bone marrow transplantation (BMT). In these reports, cells of a bone marrow (BM) origin are able to differentiate into endometrial cells, although their contribution to endometrial regeneration is not yet clear. We have previously demonstrated the functional relevance of side population (SP) cells as the endogenous source of somatic stem cells (SSC) in the human endometrium. The present work aims to understand the presence and contribution of bone marrow-derived cells to the endometrium and the endometrial SP population of women who received BMT from male donors. Five female recipients with spontaneous or induced menstruations were selected and their endometrium was examined for the contribution of XY donor-derived cells using fluorescent in situ hybridization (FISH), telomapping and SP method investigation. We confirm the presence of XY donor-derived cells in the recipient endometrium ranging from 1.7% to 2.62%. We also identify 0.45-0.85% of the donor-derived cells in the epithelial compartment displaying CD9 marker, and 1.0-1.83% of the Vimentin-positive XY donor-derived cells in the stromal compartment. Although the percentage of endometrial SP cells decreased, possibly being due to chemotherapy applied to these patients, they were not formed by XY donor-derived cells, donor BM cells were not associated with the stem cell (SC) niches assessed by telomapping technique, and engraftment percentages were very low with no correlation between time from transplant and engraftment efficiency, suggesting random terminal differentiation. In conclusion, XY donor-derived cells of a BM origin may be considered a limited exogenous source of transdifferentiated endometrial cells rather than a cyclic source of BM donor-derived stem cells.