Characterization of endometrial mesenchymal stem-like cells obtained by endometrial biopsy during routine diagnostics

The issue of heterogeneity of MSC-based advanced therapy medicinal products-a review

Mesenchymal stromal stem cells (MSCs) possess a remarkable potential for numerous clinical applications due to their unique properties including self-renewal, immunomodulation, paracrine actions and multilineage differentiation. However, the translation of MSC-based Advanced Therapy Medicinal Products (ATMPs) into the clinic has frequently met with inconsistent outcomes. One of the suspected reasons for this issue is the inherent and extensive variability that exists among such ATMPs, which makes the interpretation of their clinical efficacy difficult to assess, as well as to compare the results of various studies. This variability stems from numerous reasons including differences in tissue sources, donor attributes, variances in manufacturing protocols, as well as modes of administration. MSCs can be isolated from various tissues including bone marrow, umbilical cord, adipose tissue and others, each with its unique phenotypic and functional characteristics. While MSCs from different sources do share common features, they also exhibit distinct gene expression profiles and functional properites. Donor-specific factors such as age, sex, body mass index, and underlying health conditions can influence MSC phenotype, morphology, differentiation potential and function. Moreover, variations in preparation of MSC products introduces additional heterogeneity as a result of cell culture media composition, presence or absence of added growth factors, use of different serum supplements and culturing techniques. Once MSC products are formulated, storage protocols play a pivotal role in its efficacy. Factors that affect cell viability include cell concentration, delivery solution and importantly, post-thawing protocols where applicable. Ensuing, differences in administration protocols can critically affect the distribution and functionallity of administered cells. As MSC-based therapies continue to advance through numerous clinical trials, implication of strategies to reduce product heterogeneity is imperative. Central to addressing these challenges is the need for precise prediction of clinical responses, which require well-defined MSC populations and harmonized assessment of their specific functions. By addressing these issues by meaningful approaches, such as, e.g., MSC pooling, the field can overcome barriers to advance towards more consistent and effective MSC-based therapies.

Electrical Stimulation of Mesenchymal Stem Cells as a Tool for Proliferation and Differentiation in Cartilage Tissue Engineering: A Scaffold-Based Approach

Electrical stimulation (ES) is a widely discussed topic in the field of cartilage tissue engineering due to its ability to induce chondrogenic differentiation (CD) and proliferation. It shows promise as a potential therapy for osteoarthritis (OA). In this study, we stimulated mesenchymal stem cells (MSCs) incorporated into collagen hydrogel (CH) scaffolds, consisting of approximately 500,000 cells each, for 1 h per day using a 2.5 Vpp (119 mV/mm) 8 Hz sinusoidal signal. We compared the cell count, morphology, and CD on days 4, 7, and 10. The results indicate proliferation, with an increase ranging from 1.86 to 9.5-fold, particularly on day 7. Additionally, signs of CD were observed. The stimulated cells had a higher volume, while the stimulated scaffolds showed shrinkage. In the ES groups, up-regulation of collagen type 2 and aggrecan was found. In contrast, SOX9 was up-regulated in the control group, and MMP13 showed a strong up-regulation, indicating cell stress. In addition to lower stress levels, the control groups also showed a more spheroidic shape. Overall, scaffold-based ES has the potential to achieve multiple outcomes. However, finding the appropriate stimulation pattern is crucial for achieving successful chondrogenesis.

Glioma-associated mesenchymal stem cells

Recent studies have revealed that glioma-associated mesenchymal stem cells play instrumental roles in tumorigenesis and tumour progression and cannot be ignored as a cellular component of the glioma microenvironment. Nevertheless, the origin of these cells and their roles are poorly understood. The only relevant studies have shown that glioma-associated mesenchymal stem cells play a large role in promoting tumour proliferation, invasion and angiogenesis. This review provides a comprehensive summary of their discovery and definition, origin, differences from other tissue-derived mesenchymal stem cells, spatial distribution, functions and prognostic and therapeutic opportunities to deepen the understanding of these cells and provide new insight into the treatment of glioma.

Long-term maintenance of human endometrial epithelial organoids and their stem cell properties

The endometrium undergoes dynamic changes throughout the menstrual cycle and pregnancy, which is unique to primates. Endometrium remodeling is essential for the implantation and nutritional support of the conceptus. Despite this, the role of uterine glands in driving endometrial tissue remodeling is still poorly understood. To address this, a 3-dimensional culture system was used to generate endometrial epithelial organoids from human endometrium biopsies. These organoids are genetically stable, long-term expandability. They reproduce some functions of uterine glands in vivo. The epithelial organoids exhibit characteristics of stem cells, with the proportion of stem cells increasing with culture time and passage number. Long-term maintenance of organoids strongly expressed stemness related genes accompanied by a decrease expression in mature epithelial gene, which suggests the organoids had switched from a mature stage to a progenitor stage. Thus we proposed the possible markers for epithelial progenitors. Meanwhile, long-term cultured organoids exhibit an increase in the proportion of luminal epithelial stem cells, accompanied by a decrease of glandular epithelial stem cells. Organoids also show hormone responsiveness, reflecting the various stages of the menstrual cycle and early pregnancy.

Sox-2 positive cells identified in lymph nodes from endometriosis patients may play a role in the disease pathogenesis

OBJECTIVE

This study aimed to characterize Sox-2 in sentinel lymph nodes and randomly obtained lymph nodes from endometriosis (EM) patients for the first time.

STUDY DESIGN

This prospective study analyzed tissue samples from surgical specimens collected from May until December 2007 in the Endometriosis Center Charité, Berlin. Lymph node samples from 38 women aged between 22 and 49 years who underwent laparoscopy due to symptomatic EM were analyzed. The material was obtained either randomly or, in the case of deep infiltrating endometriosis, detected using 4 cc Patent Blue®, labeled intraoperatively, which made the sentinel lymph nodes available for histological examination. Together with hematoxylin and eosin staining, the sections were evaluated by immunohistochemistry with antibodies against estrogen and progesterone receptors and Sox-2. Using double-immunofluorescence microscopy, the colocalization of Sox-2 and estrogen receptors were evaluated.

RESULTS

Sox-2-positive cells were identified in the lymph nodes' cortical and medullary zones, with a higher expression in the medullary layer. Occasionally, Sox-2 positive stained cell groups, called cell nests, could also be detected. The number of Sox-2 positive cells in the sentinel lymph nodes was almost three times higher than in the random lymph nodes (p = 0.031). A significant five-fold increase (p = 0.0013) in Sox-2 expression was seen in the estrogen and progesterone receptor (ER/PR) positive patient group compared to the progesterone receptor positive group or hormone receptor negative patients. Identical hormone-related Sox-2 expression was also detected separately for the sentinel lymph node group (p = 0.0174). Sox-2 showed pronounced colocalisation with estrogen receptors.

CONCLUSION

The lymphatic involvement in EM is evidence of a systemic disease manifestation and provides evidence of an immune system failure. In recent years, many theories have been studied, but there is no single theory that could explain all aspects of EM. The future concept of EM is likely to incorporate the elements from all the pathogenetic theories already described. Through this study, stem cells and lymphatic metastasis theories were incorporated.

Endometrial Stem Cells and Their Applications in Intrauterine Adhesion

Intrauterine adhesion (IUA), resulting from pregnancy or nonpregnant uterine trauma, is one of the major causes of abnormal menstruation, infertility, or repeated pregnancy loss. Although a few methods, including hysteroscopy and hormone therapy, are routinely used for its diagnosis and treatment, they cannot restore tissue regeneration. Stem cells, which have self-renewal and tissue regeneration abilities, have been proposed as a promising therapy for patients with severe IUAs. In this review, we summarize the origin and features of endometrium-associated stem cells and their applications in the treatment of IUAs based on animal models and human clinical trials. We expect that this information will help to elucidate the underlying mechanism for tissue regeneration and to improve the design of stem cell-based therapies for IUAs.

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.

Impact of Musashi-1 and Musashi-2 Double Knockdown on Notch Signaling and the Pathogenesis of Endometriosis

The stem cell marker and RNA-binding protein Musashi-1 is overexpressed in endometriosis. Musashi-1-siRNA knockdown in Ishikawa cells altered the expression of stem cell related genes, such as OCT-4. To investigate the role of both human Musashi homologues (MSI-1 and MSI-2) in the pathogenesis of endometriosis, immortalized endometriotic 12-Z cells and primary endometriotic stroma cells were treated with Musashi-1- and Musashi-2-siRNA. Subsequently, the impact on cell proliferation, cell apoptosis, cell necrosis, spheroid formation, stem cell phenotype and the Notch signaling pathway was studied in vitro. Using the ENDOMET Turku Endometriosis database, the gene expression of stem cell markers and Notch signaling pathway constituents were analyzed according to localization of the endometriosis lesions. The database analysis demonstrated that expression of Musashi and Notch pathway-related genes are dysregulated in patients with endometriosis. Musashi-1/2-double-knockdown increased apoptosis and necrosis and reduced stem cell gene expression, cell proliferation, and the formation of spheroids. Musashi silencing increased the expression of the anti-proliferation mediator p21. Our findings suggest the therapeutic potential of targeting the Musashi–Notch axis. We conclude that the Musashi genes have an impact on Notch signaling and the pathogenesis of endometriosis through the downregulation of proliferation, stemness characteristics and the upregulation of apoptosis, necrosis and of the cell cycle regulator p21.

WNT5A Interacts With FZD5 and LRP5 to Regulate Proliferation and Self-Renewal of Endometrial Mesenchymal Stem-Like Cells

Endometrial mesenchymal stem-like cells (eMSC) reside in the basal layer of the endometrium and are responsible for cyclic regeneration during the reproductive lives of women. Myometrial cells act as a component of the niche and regulate the stem cell fate through the activation of WNT/β-catenin signaling via WNT5A. Since WNT5A-responsive mechanisms on eMSC are still uncertain, we hypothesize that the WNT ligand–WNT5A works to activate WNT/β-catenin signaling through binding to Frizzled receptors (FZDs) and co-receptor low-density lipoprotein receptor-related protein 5 (LRP5). Among the various receptors that have been reported to interact with WNT5A, we found FZD5 abundantly expressed by eMSC when compared to unfractionated stromal cells. Neutralizing the protein expression by using anti-FZD5 antibody suppressed the stimulatory effects on phenotypic expression and the clonogenicity of eMSC in a myometrial cell–eMSC co-culture system as well as in an L-Wnt5a conditioned medium. Gene silencing of FZD5 not only reduced the binding of WNT5A to eMSC but also decreased the TCF/LEF transcriptional activities and expression of active β-catenin. Inhibition of LRP coreceptors with recombinant Dickkopf-1 protein significantly reduced the binding affinity of eMSC to WNT5A as well as the proliferation and self-renewal activity. During postpartum remodeling in mouse endometrium, active β-catenin (ABC) was detected in label-retaining stromal cells (LRSCs), and these ABC+ LRSCs express FZD5 and LRP5, suggesting the activation of WNT/β-catenin signaling. In conclusion, our findings demonstrate the interaction of WNT5A, FZD5, and LRP5 in regulating the proliferation and self-renewal of eMSC through WNT/β-catenin signaling.

Making More Womb: Clinical Perspectives Supporting the Development and Utilization of Mesenchymal Stem Cell Therapy for Endometrial Regeneration and Infertility

The uterus is a homeostatic organ, unwavering in the setting of monthly endometrial turnover, placental invasion, and parturition. In response to ovarian steroid hormones, the endometrium autologously prepares for embryo implantation and in its absence will shed and regenerate. Dysfunctional endometrial repair and regeneration may present clinically with infertility and abnormal menses. Asherman's syndrome is characterized by intrauterine adhesions and atrophic endometrium, which often impacts fertility. Clinical management of infertility associated with abnormal endometrium represents a significant challenge. Endometrial mesenchymal stem cells (MSC) occupy a perivascular niche and contain regenerative and immunomodulatory properties. Given these characteristics, mesenchymal stem cells of endometrial and non-endometrial origin (bone marrow, adipose, placental) have been investigated for therapeutic purposes. Local administration of human MSC in animal models of endometrial injury reduces collagen deposition, improves angiogenesis, decreases inflammation, and improves fertility. Small clinical studies of autologous MSC administration in infertile women with Asherman's Syndrome suggested their potential to restore endometrial function as evidenced by increased endometrial thickness, decreased adhesions, and fertility. The objective of this review is to highlight translational and clinical studies investigating the use of MSC for endometrial dysfunction and infertility and to summarize the current state of the art in this promising area.

Mesenchymal stem/stromal cells in cancer therapy

The multipotent mesenchymal stem/stromal cells (MSCs), initially discovered from bone marrow in 1976, have been identified in nearly all tissues of human body now. The multipotency of MSCs allows them to give rise to osteocytes, chondrocytes, adipocytes, and other lineages. Moreover, armed with the immunomodulation capacity and tumor-homing property, MSCs are of special relevance for cell-based therapies in the treatment of cancer. However, hampered by lack of knowledge about the controversial roles that MSC plays in the crosstalk with tumors, limited progress has been made with regard to translational medicine. Therefore, in this review, we discuss the prospects of MSC-associated anticancer strategies in light of therapeutic mechanisms and signal transduction pathways. In addition, the clinical trials designed to appraise the efficacy and safety of MSC-based anticancer therapies will be assessed according to published data.

When Origin Matters: Properties of Mesenchymal Stromal Cells From Different Sources for Clinical Translation in Kidney Disease

Advanced therapy medicinal products (ATMPs) offer new prospects to improve the treatment of conditions with unmet medical needs. Kidney diseases are a current major health concern with an increasing global prevalence. Chronic renal failure appears after many years of impairment, which opens a temporary window to apply novel therapeutic approaches to delay or halt disease progression. The immunomodulatory, anti-inflammatory, and pro-regenerative properties of mesenchymal stromal cells (MSCs) have sparked interest for their use in cell-based regenerative therapies. Currently, several early-phase clinical trials have been completed and many are ongoing to explore MSC safety and efficacy in a wide range of nephropathies. However, one of the current roadblocks to the clinical translation of MSC therapies relates to the lack of standardization and harmonization of MSC manufacturing protocols, which currently hinders inter-study comparability. Studies have shown that cell culture processing variables can have significant effects on MSC phenotype and functionality, and these are highly variable across laboratories. In addition, heterogeneity within MSC populations is another obstacle. Furthermore, MSCs may be isolated from several sources which adds another variable to the comparative assessment of outcomes. There is now a growing body of literature highlighting unique and distinctive properties of MSCs according to the tissue origin, and that characteristics such as donor, age, sex and underlying medical conditions may alter the therapeutic effect of MSCs. These variables must be taken into consideration when developing a cell therapy product. Having an optimal scale-up strategy for MSC manufacturing is critical for ensuring product quality while minimizing costs and time of production, as well as avoiding potential risks. Ideally, optimal scale-up strategies must be carefully considered and identified during the early stages of development, as making changes later in the bioprocess workflow will require re-optimization and validation, which may have a significant long-term impact on the cost of the therapy. This article provides a summary of important cell culture processing variables to consider in the scale-up of MSC manufacturing as well as giving a comprehensive review of tissue of origin-specific biological characteristics of MSCs and their use in current clinical trials in a range of renal pathologies.

An In Vitro and In Vivo Comparison of Osteogenic Differentiation of Human Mesenchymal Stromal/Stem Cells

The use of stem cells in regenerative medicine, including tissue engineering and transplantation, has generated a great deal of enthusiasm. Mesenchymal stromal/stem cells (MSCs) can be isolated from various tissues, most commonly, bone marrow but more recently adipose tissue, dental pulp, and Wharton's jelly, to name a few. MSCs display varying phenotypic profiles and osteogenic differentiating capacity depending and their site of origin. MSCs have been successfully differentiated into osteoblasts both in vitro an in vivo but discrepancies exist when the two are compared: what happens in vitro does not necessarily happen in vivo, and it is therefore important to understand why these differences occur. The osteogenic process is a complex network of transcription factors, stimulators, inhibitors, proteins, etc., and in vivo experiments are helpful in evaluating the various aspects of this osteogenic process without distractions and confounding variables. With that in mind, the results of in vitro experiments need to be carefully considered and interpreted with caution as they do not perfectly replicate the conditions found within living organisms. This is where in vivo experiments help us better understand interactions that might occur in the osteogenic process that cannot be replicated in vitro. Potentially, these differences could also be exploited to develop an optimal MSC cell therapeutic product that can be used for bone disorders. There are many bone disorders, most of which cause a great deal of discomfort. Clinically acceptable protocols could be developed in which MSCs are used to aid in bone regeneration providing relief for patients with chronic pain. The aim of this review is to examine the differences between studies conducted in vitro and in vivo with regard to the osteogenic process to better define the gaps in current osteogenic research. By better understanding osteogenic differentiation, we can better define treatment strategies for various bone disorders.

Characterization and response to inflammatory stimulation of human endometrial-derived mesenchymal stem/stromal cells

BACKGROUND AIMS

The human endometrium has emerged as an attractive source of endometrial-derived mesenchymal stem/stromal cells (eMSCs) that can be easily isolated by non-invasive procedures. The prominent capacity of the endometrium for efficient and scarless regeneration each menstrual cycle indicates the increased eMSC immunomodulatory and pro-angiogenic properties. Herein the authors investigated the molecular responses of eMSCs to an inflammatory environment and whether those intrinsic responses affected their functional attributes.

METHODS

Human eMSCs immunophenotypic, transcriptional and secretory profiles were evaluated at passage three (P3) and passage eight (P8) to determine culture effects. Functionally, P3 and P8 non-induced and TNF-α/IFN-γ-induced eMSCs were interrogated for their capacity to suppress stimulated peripheral blood mononuclear cell (PBMC) proliferation, whereas non-induced eMSCs were assessed for their support to vascular network formation in co-cultures with human umbilical vein endothelial cells in vitro.

RESULTS

Non-induced P3 and P8 eMSCs exhibited similar spindle-shaped morphology and clonogenic capacity. Nevertheless, P8 eMSCs showed reduced growth rate capacity and telomere length. The eMSCs displayed the typical MSC-related immunophenotypic profile, with P3 and P8 eMSCs expressing high levels (>98%) of CD140β, intermediate levels (35-60%) of CD146 and SUSD2 and low levels (∼8%) of NG2 pericytic markers. Non-induced P3 and P8 showed similar transcriptional and secretory profiles, though the expression of immunomodulatory HLA-G and IL-8 genes was significantly downregulated in P8 compared with P3 eMSCs. Upon TNF-α/IFN-γ induction, eMSCs showed an immunophenotypic profile similar to that of non-induced eMSCs, except for significant upregulation of HLA-DR protein expression in both induced P3 and P8 eMSCs. However, induced P3 and P8 eMSCs showed significant upregulation of CD10, HLA-G, IDO, IL-6, IL-8, LIF and TSG gene expression compared with non-induced cultures. TNF-α/IFN-γ induction strongly increased the secretion of inflammatory-/angiogenesis-related molecules, whereas growth factor secretion was similar to the non-induced eMSCs. Functionally, P3 and P8 eMSCs showed a strong inhibitory effect on stimulated PBMC proliferation and the capacity to support neovascularization in vitro.

CONCLUSIONS

The authors' study suggests that serial expansion does not affect eMSC immunophenotypic, transcriptional and secretory profiles. This is directly reflected by the functional immunomodulatory and pro-angiogenic properties of eMSCs, which remain unaltered until P8 in vitro. However, exposure of eMSCs to inflammatory environments enhances their immunomodulatory transcriptional and inflammatory-/angiogenesis-related secretory profiles. Therefore, the resulting evidence of eMSCs serial expansion and exposure to inflammation could serve as a foundation for improved eMSCs manufacturing and potential clinical translation efforts.

The ellagic acid metabolites urolithin A and B differentially affect growth, adhesion, motility, and invasion of endometriotic cells in vitro

STUDY QUESTION

What are the effects of plant-derived antioxidant compounds urolithin A (UA) and B (UB) on the growth and pathogenetic properties of an in vitro endometriosis model?

SUMMARY ANSWER

Both urolithins showed inhibitory effects on cell behavior related to the development of endometriosis by differentially affecting growth, adhesion, motility, and invasion of endometriotic cells in vitro.

WHAT IS KNOWN ALREADY

Endometriosis is one of the most common benign gynecological diseases in women of reproductive age and is defined by the presence of endometrial tissue outside the uterine cavity. As current pharmacological therapies are associated with side effects interfering with fertility, we aimed at finding alternative therapeutics using natural compounds that can be administered for prolonged periods with a favorable side effects profile.

STUDY DESIGN, SIZE, DURATION

In vitro cultures of primary endometriotic stromal cells from 6 patients subjected to laparoscopy for benign pathologies with histologically confirmed endometriosis; and immortalized endometrial stromal (St-T1b) and endometriotic epithelial cells (12Z) were utilized to assess the effects of UA and UB on endometriotic cell properties. Results were validated in three-dimensional (3D) in vitro co-culture spheroids of 12Z and primary endometriotic stroma cells of one patient, and organoids from 3 independent donors with endometriosis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The effects on cell growth were measured by non-radioactive colorimetric assay to measure cellular metabolic activity as an indicator of cell viability (MTT assay) and flow cytometric cell cycle assay on primary cultures, St-T1b, and 12Z. Apoptosis analyses, the impact on in vitro adhesion, migration, and invasion were evaluated in the cell lines. Moreover, Real-Time Quantitative Reverse Transcription polymerase chain reaction (RT-qPCR) assays were performed on primary cultures, St- T1b and 12Z to evaluate a plausible mechanistic contribution by factors related to proteolysis (matrix metalloproteinase 2, 3 and 9 -MMP2, MMP3, MMP9-, and tissue inhibitor of metalloproteinases -TIMP-1-), cytoskeletal regulators (Ras-related C3 botulinum toxin substrate 1 -RAC1-, Rho-associated coiled-coil containing protein kinase 2 -ROCK2-), and cell adhesion molecules (Syndecan 1 -SDC1-, Integrin alpha V-ITGAV-). Finally, the urolithins effects were evaluated on spheroids and organoids by formation, viability, and drug screen assays.

MAIN RESULTS AND THE ROLE OF CHANCE

40 µM UA and 20 µM UB produced a significant decrease in cell proliferation in the primary endometriotic cell cultures (P < 0.001 and P < 0.01, respectively) and in the St-T1b cell line (P < 0.001 and P < 0.05, respectively). In St-T1b, UA exhibited a mean half-maximum inhibitory concentration (IC50) of 39.88 µM, while UB exhibited a mean IC50 of 79.92 µM. Both 40 µM UA and 20 µM UB produced an increase in cells in the S phase of the cell cycle (P < 0.01 and P < 0.05, respectively). The same concentration of UA also increased the percentage of apoptotic ST-t1b cells (P < 0.05), while both urolithins decreased cell migration after 24 h (P < 0.001 both). Only the addition of 5 µM UB decreased the number of St-T1b adherent cells. TIMP-1 expression was upregulated in response to treating the cells with 40 µM UA (P < 0.05). Regarding the 12Z endometriotic cell line, only 40 µM UA decreased proliferation (P < 0.01); while both 40 µM UA and 20 µM UB produced an increase in cells in the G2/M phase (P < 0.05 and P < 0.01, respectively). In this cell line, UA exhibited a mean IC50 of 40.46 µM, while UB exhibited a mean IC50 of 54.79 µM. UB decreased cell migration (P < 0.05), and decreased the number of adherent cells (P < 0.05). Both 40 µM UA and 20 µM UB significantly decreased the cellular invasion of these cells; and several genes were altered when treating the cells with 40 µM UA and 10 µM UB. The expression of MMP2 was downregulated by UA (P < 0.001), and expression of MMP3 (UA P < 0.001 and UB P < 0.05) and MMP9 (P < 0.05, both) were downregulated by both urolithins. Moreover, UA significantly downregulated ROCK2 (P < 0.05), whereas UB treatment was associated with RAC1 downregulation (P < 0.05). Finally, the matrix adhesion receptors and signaling (co)receptors SDC1 and ITGAV were downregulated upon treatment with either UA or UB (P < 0.01 and P < 0.05, respectively in both cases). Regarding the effects of urolithins on 3D models, we have seen that they significantly decrease the viability of endometriosis spheroids (80 µM UA and UB: P < 0.05 both) as well as affecting their area (40 µM UA: P < 0.05, and 80 µM UA: P < 0.01) and integrity (40 µM UA and UB: P < 0.05, 80 µM UA and UB: P < 0.01). On the other hand, UA and UB significantly inhibited organoid development/outgrowth (40 and 80 µM UA: P < 0.0001 both; 40 µM UB: P < ns-0.05-0.001, and 80 µM UB: P < 0.01-0.001-0.001), and all organoid lines show urolithins sensitivity resulting in decreasing viability (UA exhibited a mean IC50 of 33.93 µM, while UB exhibited a mean IC50 of 52.60 µM).

LARGE-SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

This study was performed on in vitro endometriosis models.

WIDER IMPLICATIONS OF THE FINDINGS

These in vitro results provide new insights into the pathogenetic pathways affected by these compounds and mark their use as a potential new therapeutic strategy for the treatment of endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded EU MSCA-RISE-2015 project MOMENDO (691058). The authors have no conflicts of interest to declare.

Pluripotent stem cell-derived endometrial stromal fibroblasts in a cyclic, hormone-responsive, coculture model of human decidua

Various human diseases and pregnancy-related disorders reflect endometrial dysfunction. However, rodent models do not share fundamental biological processes with the human endometrium, such as spontaneous decidualization, and no existing human cell cultures recapitulate the cyclic interactions between endometrial stromal and epithelial compartments necessary for decidualization and implantation. Here we report a protocol differentiating human pluripotent stem cells into endometrial stromal fibroblasts (PSC-ESFs) that are highly pure and able to decidualize. Coculture of PSC-ESFs with placenta-derived endometrial epithelial cells generated organoids used to examine stromal-epithelial interactions. Cocultures exhibited specific endometrial markers in the appropriate compartments, organization with cell polarity, and hormone responsiveness of both cell types. Furthermore, cocultures recapitulate a central feature of the human decidua by cyclically responding to hormone withdrawal followed by hormone retreatment. This advance enables mechanistic studies of the cyclic responses that characterize the human endometrium.

Cell-based endometrial regeneration: current status and future perspectives

Endometrial-related disorders including Asherman's syndrome, thin endometrium, pelvic organ prolapse, and cesarean scar pregnancies can be accompanied by different symptoms such as amenorrhea, infertility, abnormal placental implantation and recurrent miscarriage. Different methods have been introduced to overcome these problems such as surgery and hormonal therapy but none of them has shown promising outcomes. On the other hand, the development of novel regenerative therapeutic strategies has opened new avenues for the treatment of endometrial-related deficiencies. In this regard, different types of scaffolds, acellular matrices and also cell therapy with adult or stem cells have been investigated for the treatment of endometrial-related deficiencies. In this paper, we review the current status of cell-based endometrium regeneration using scaffold dependent and scaffold-free methods and future perspectives in this field. Moreover, we discuss the endometrial diseases that can be candidates for cell-based treatments. Also, the cells with the potential for endometrial regeneration are explained.

Endometrial Stem/Progenitor cell (ES/PC) Marker Expression Profile in Adenosarcoma and Endometrial Stromal Sarcoma

BACKGROUND

The uterus is one of the most dynamic organs in the human body, and this dynamic homeostasis is supported by endometrial stem/progenitor cells (ES/PCs), which are heterogeneous in their phenotype and degree of differentiation. ES/PCs are generally localized in the endometrial stroma, the site of origin for adenosarcoma and endometrial stromal sarcoma (ESS). Subsets of ESSs and adenosarcomas harbor SUZ12 or DICER1 gene alterations, two genes with roles in embryonic stem cell biology. However, the possible contribution of ES/PCs to tumorigenesis is unexplored.

METHOD

We examined the expression of eleven ES/PC markers, along with three proteins expressed in the mature endometrial stroma (ER, PR and CD10) in 60 uterine tumors (24 low-, 11 high-grade ESS, 25 adenosarcomas). Protein expression profiles were assessed by unsupervised hierarchical clustering. miRNA expression profiles were examined in a subset of adenosarcoma with/without DICER1 mutations, using the NanoString platform.

RESULTS

ES/PC markers were variably expressed, and the tumors exhibited limited immunophenotypic resemblance to different ES/PCs. Within the ESSs, the ES/PC marker clustering pattern was prognostic for both overall and disease-free survival. Comparing adenosarcomas and ESSs, most high-grade ESSs clustered with one another, while low-grade ESSs and adenosarcomas tended to cluster with one another. Among the adenosarcomas, the miRNA expression profiles were varied with respect to the DICER1 mutation status, with pathway analysis pointing to dysregulated signal transduction and stem cell biology.

CONCLUSIONS

ESSs and adenosarcomas exhibit varying immunophenotypic resemblance to ES/PCs. These expression profiles have prognostic implications and may be genetically driven.

Stem Cells and the Endometrium: From the Discovery of Adult Stem Cells to Pre-Clinical Models

Adult stem cells (ASCs) were long suspected to exist in the endometrium. Indeed, several types of endometrial ASCs were identified in rodents and humans through diverse isolation and characterization techniques. Putative stromal and epithelial stem cell niches were identified in murine models using label-retention techniques. In humans, functional methods (clonogenicity, long-term culture, and multi-lineage differentiation assays) and stem cell markers (CD146, SUSD2/W5C5, LGR5, NTPDase2, SSEA-1, or N-cadherin) facilitated the identification of three main types of endogenous endometrial ASCs: stromal, epithelial progenitor, and endothelial stem cells. Further, exogenous populations of stem cells derived from bone marrow may act as key effectors of the endometrial ASC niche. These findings are promoting the development of stem cell therapies for endometrial pathologies, with an evolution towards paracrine approaches. At the same time, promising therapeutic alternatives based on bioengineering have been proposed.

Old Friends with Unexploited Perspectives: Current Advances in Mesenchymal Stem Cell-Based Therapies in Asthma

Mesenchymal stem cells (MSCs) have a great regenerative and immunomodulatory potential that was successfully tested in numerous pre-clinical and clinical studies of various degenerative, hematological and inflammatory disorders. Over the last few decades, substantial immunoregulatory effects of MSC treatment were widely observed in different experimental models of asthma. Therefore, it is tempting to speculate that stem cell-based treatment could become an attractive means to better suppress asthmatic airway inflammation, especially in subjects resistant to currently available anti-inflammatory therapies. In this review, we discuss mechanisms accounting for potent immunosuppressive properties of MSCs and the rationale for their use in asthma. We describe in detail an intriguing interplay between MSCs and other crucial players in the immune system as well as lung microenvironment. Finally, we reveal the potential of MSCs in maintaining airway epithelial integrity and alleviating lung remodeling.

Characteristics of the human endometrial regeneration cells as a potential source for future stem cell-based therapies: A lab resources study

Background

Human endometrium with consecutive regeneration capability undergoes monthly hormonal changes for probable implantation, which confirms the presence of the cells in the basalis layer known as stem cell.

Objective

Previously, we reported the isolation and culture of the mesenchymal-like cells from human endometrium. In this study, we evaluated the biological and stemness characteristics of these cells.

Materials and Methods

The characterization of Yazd human endometrial-derived mesenchymal stem/stromal cells (YhEnMSCs) was assessed using immunofluorescence (IF) staining for CD105, VIMENTIN, and FIBRONECTIN as markers and RT-PCR for CD166, CD10, CD105, VIMENTIN, FIBRONECTIN, MHCI, CD14, and MHCII genes. Flow cytometry (FACS) was performed for CD44, CD73, CD90, and CD105 markers. Moreover, the differentiation capacity of the YhEnMSCs to the osteoblast and adipocytes was confirmed by Alizarin Red and Oil Red staining.

Results

YhEnMSCs expressed CD105, VIMENTIN, FIBRONECTIN, CD44, CD73, and CD90 markers and CD166, CD10, CD105, VIMENTIN, FIBRONECTIN, and MHCI, but, did not express CD14, MHCII.

Conclusion

Our data confirm previous reports by other groups indicating the application of endometrial cells as an available source of MSCs with self-renewal and differentiation capacity. Accordingly, YhEnMSCs can be used as a suitable source for cell-based therapies.

Intrinsic Angiogenic Potential and Migration Capacity of Human Mesenchymal Stromal Cells Derived from Menstrual Blood and Bone Marrow

Several therapies are being developed to increase blood circulation in ischemic tissues. Despite bone marrow-derived mesenchymal stromal cells (bmMSC) are still the most studied, an interesting and less invasive MSC source is the menstrual blood, which has shown great angiogenic capabilities. Therefore, the aim of this study was to evaluate the angiogenic properties of menstrual blood-derived mesenchymal stromal cells (mbMSC) in vitro and in vivo and compared to bmMSC. MSC’s intrinsic angiogenic capacity was assessed by sprouting and migration assays. mbMSC presented higher invasion and longer sprouts in 3D culture. Additionally, both MSC-spheroids showed cells expressing CD31. mbMSC and bmMSC were able to migrate after scratch wound in vitro, nonetheless, only mbMSC demonstrated ability to engraft in the chick embryo, migrating to perivascular, perineural, and chondrogenic regions. In order to study the paracrine effects, mbMSC and bmMSC conditioned mediums were capable of stimulating HUVEC’s tube-like formation and migration. Both cells expressed VEGF-A and FGF2. Meanwhile, PDGF-B was expressed exclusively in mbMSC. Our results indicated that mbMSC and bmMSC presented a promising angiogenic potential. However, mbMSC seems to have additional advantages since it can be obtained by non-invasive procedure and expresses PDGF-B, an important molecule for vascular formation and remodeling.

Application of Mesenchymal Stem Cells in Inflammatory and Fibrotic Diseases

Mesenchymal stem cells (MSCs) are multipotent stem cells that can be isolated from various tissues in the adult body. MSCs should be characterized by three criteria for regenerative medicine. MSCs must (1) adhere to plastic surfaces, (2) express specific surface antigens, and (3) differentiate into mesodermal lineages, including chondrocytes, osteoblasts, and adipocytes, in vitro. Interestingly, MSCs have immunomodulatory features and secrete trophic factors and immune receptors that regulate the microenvironment in host tissue. These specific and unique therapeutic properties make MSCs ideal as therapeutic agents in vivo. Specifically, pre-clinical and clinical investigators generated inflammatory and fibrotic diseases models, and then transplantation of MSCs into diseases models for therapeutic effects investigation. In this review, we characterize MSCs from various tissues and describe their applications for treating various inflammation and fibrotic diseases.

miR-142-3p Reduces the Size, Migration, and Contractility of Endometrial and Endometriotic Stromal Cells by Targeting Integrin- and Rho GTPase-Related Pathways That Regulate Cytoskeletal Function

Downregulated microRNA-142-3p signaling contributes to the pathogenesis of endometriosis, an invasive disease where the lining of the uterus grows at ectopic locations, by yet incompletely understood mechanisms. Using bioinformatics and in vitro assays, this study identifies cytoskeletal regulation and integrin signaling as two relevant categories of miR-142-3p targets. qPCR revealed that miR-142-3p upregulation in St-T1b cells downregulates Rho-associated protein kinase 2 (ROCK2), cofilin 2 (CFL2), Ras-related C3 botulinum toxin substrate 1 (RAC1), neural Wiskott-Aldrich syndrome protein (WASL), and integrin α-V (ITGAV). qPCR and Western-blotting showed miR-142-3p effect on WASL and ITGAV was significant also in primary endometriotic stroma cells. Luciferase reporter assays in ST-T1b cells then confirmed direct regulation of ITGAV and WASL. On the functional side, miR-142-3p upregulation significantly reduced ST-T1b cell size, the size of vinculin plaques, migration through fibronectin-coated transwell filters, and the ability of ST-T1b and primary endometriotic stroma cells to contract collagen I gels. These results suggest that miR-142-3p has a strong mechanoregulatory effect on endometrial stroma cells and its external administration reduces the invasive endometrial phenotype. Within the limits of an in vitro investigation, our study provides new mechanistic insights into the pathogenesis of endometriosis and provides a perspective for the development of miR-142-3p based drugs for inhibiting invasive growth of endometriotic cells.

Adenomyosis: Mechanisms and Pathogenesis

Adenomyosis is a common disorder of the uterus, and is associated with an enlarged uterus, heavy menstrual bleeding (HMB), pelvic pain, and infertility. It is characterized by endometrial epithelial cells and stromal fibroblasts abnormally found in the myometrium where they elicit hyperplasia and hypertrophy of surrounding smooth muscle cells. While both the mechanistic processes and the pathogenesis of adenomyosis are uncertain, several theories have been put forward addressing how this disease develops. These include intrinsic or induced (1) microtrauma of the endometrial-myometrial interface; (2) enhanced invasion of endometrium into myometrium; (3) metaplasia of stem cells in myometrium; (4) infiltration of endometrial cells in retrograde menstrual effluent into the uterine wall from the serosal side; (5) induction of adenomyotic lesions by aberrant local steroid and pituitary hormones; and (6) abnormal uterine development in response to genetic and epigenetic modifications. Dysmenorrhea, HMB, and infertility are likely results of inflammation, neurogenesis, angiogenesis, and contractile abnormalities in the endometrial and myometrial components. Elucidating mechanisms underlying the pathogenesis of adenomyosis raise possibilities to develop targeted therapies to ameliorate symptoms beyond the current agents that are largely ineffective. Herein, we address these possible etiologies and data that support underlying mechanisms.

Endometrial stromal cells exhibit a distinct phenotypic and immunomodulatory profile

BACKGROUND

In Asherman's syndrome (AS), intrauterine scarring and fibrotic adhesions lead to menstrual disorders, pregnancy loss, or infertility. A few clinical trials have piloted cell therapy to overcome AS. Understanding the role of the stromal compartment in endometrial regeneration remains poorly understood. We hypothesize that endometrial stromal cells (eSCs) represent a relevant cell population to establish novel cell-based therapeutics for endometrial disorders. The aim of this study was to characterize eSCs and evaluate their immune-cell interactions.

METHODS

eSCs were isolated from healthy donors, during the proliferative stage of the menstrual cycle. Cells were characterized for expression of mesenchymal stromal cell (MSC) markers and assessed for their tumorigenic potential. eSCs were co-cultured with interferon γ and tumor necrosis factor α, and cell surface expression of their respective receptors and human leukocyte antigen (HLA) I and II determined by flow cytometry. Secreted levels of key immunomodulatory factors were established. eSCs were cultured with activated peripheral blood mononuclear cells, and T cell differentiation and proliferation determined.

RESULTS

eSCs demonstrated an MSC surface phenotype and exhibited multipotency. Expanded eSCs retained chromosomal stability and demonstrated no tumorigenicity. Upon stimulation, eSCs licensed to an anti-inflammatory phenotype with upregulated secretion of immunomodulatory factors. Stimulated eSCs did not express HLA class II. eSCs suppressed the proliferation and activation of CD4+ T cells, with the eSC secretome further downregulating central memory T cells and upregulating effector memory (EM) cells.

CONCLUSIONS

Differential responsiveness to inflammation by eSCs, compared to other MSC sources, demonstrates the need to understand the specific functional effects of individual stromal cell sources. A lack of HLA class II and triggering of EM T cell differentiation strongly links to innate in vivo roles of eSCs in tissue repair and immune tolerance during pregnancy. We conclude that eSCs may be an ideal cell therapy candidate for endometrial disorders.

Unraveling the Molecular Signature of Extracellular Vesicles From Endometrial-Derived Mesenchymal Stem Cells: Potential Modulatory Effects and Therapeutic Applications

Endometrial-derived Mesenchymal Stem Cells (endMSCs) are involved in the regeneration and remodeling of human endometrium, being considered one of the most promising candidates for stem cell-based therapies. Their therapeutic effects have been found to be mediated by extracellular vesicles (EV-endMSCs) with pro-angiogenic, anti-apoptotic, and immunomodulatory effects. Based on that, the main goal of this study was to characterize the proteome and microRNAome of these EV-endMSCs by proteomics and transcriptomics approaches. Additionally, we hypothesized that inflammatory priming of endMSCs may contribute to modify the therapeutic potential of these vesicles. High-throughput proteomics revealed that 617 proteins were functionally annotated as Extracellular exosome (GO:0070062), corresponding to the 70% of the EV-endMSC proteome. Bioinformatics analyses allowed us to identify that these proteins were involved in adaptive/innate immune response, complement activation, antigen processing/presentation, negative regulation of apoptosis, and different signaling pathways, among others. Of note, multiplexed quantitative proteomics and Systems Biology analyses showed that IFNγ priming significantly modulated the protein profile of these vesicles. As expected, proteins involved in antigen processing and presentation were significantly increased. Interestingly, immunomodulatory proteins, such as CSF1, ERAP1, or PYCARD were modified. Regarding miRNAs expression profile in EV-endMSCs, Next-Generation Sequencing (NGS) showed that the preferred site of microRNAome targeting was the nucleus (n = 371 microTargets), significantly affecting signal transduction (GO:0007165), cell proliferation (GO:0008283), and apoptotic processes (GO:0006915), among others. Interestingly, NGS analyses highlighted that several miRNAs, such as hsa-miR-150-5p or hsa-miR-196b-5p, were differentially expressed in IFNγ-primed EV-endMSCs. These miRNAs have a functional involvement in glucocorticoid receptor signaling, IL-6/8/12 signaling, and in the role of macrophages. In summary, these results allowed us to understand the complexity of the molecular networks in EV-endMSCs and their potential effects on target cells. To our knowledge, this is the first comprehensive study based on proteomic and genomic approaches to unravel the therapeutic potential of these extracellular vesicles, that may be used as immunomodulatory effectors in the treatment of inflammatory conditions.

Partial regeneration of uterine horns in rats through adipose-derived stem cell sheets

Severe uterine damage and infection lead to intrauterine adhesions, which result in hypomenorrhea, amenorrhea and infertility. Cell sheet engineering has shown great promise in clinical applications. Adipose-derived stem cells (ADSCs) are emerging as an alternative source of stem cells for cell-based therapies. In the present study, we investigated the feasibility of applying ADSCs as seed cells to form scaffold-free cell sheet. Data showed that ADSC sheets expressed higher levels of FGF, Col I, TGFβ, and VEGF than ADSCs in suspension, while increased expression of this gene set was associated with stemness, including Nanog, Oct4, and Sox2. We then investigated the therapeutic effects of 3D ADSCs sheet on regeneration in a rat model. We found that ADSCs were mainly detected in the basal layer of the regenerating endometrium in the cell sheet group at 21 days after transplantation. Additionally, some ADSCs differentiated into stromal-like cells. Moreover, ADSC sheets transplanted into partially excised uteri promoted regeneration of the endometrium cells, muscle cells and stimulated angiogenesis, and also resulted in better pregnancy outcomes. Therefore, ADSC sheet therapy shows considerable promise as a new treatment for severe uterine damage.

γ-Secretase inhibition affects viability, apoptosis, and the stem cell phenotype of endometriotic cells

INTRODUCTION

Stem cells mediate cyclic regeneration of the endometrium. The upregulated expression of receptors and modulators of the notch signaling pathway in endometriosis suggests an involvement in the pathogenetic process. Here, we investigated the effects of notch pathway inhibition by a γ-secretase inhibitor (GSI) on stemness-associated properties of the epithelial endometriotic cell line 12Z and of primary endometriotic stroma cells.

MATERIAL AND METHODS

12Z cells and primary endometriotic stroma cells of 7 patients were treated with or without GSI, and analyzed for changes in gene expression by TaqMan low-density arrays, quantitative PCR, and flow cytometry. The functional impact of GSI treatment was studied by MTT assay, cell cycle analysis, colony formation assay, annexin V apoptosis assay, and aldehyde dehydrogenase activity assays.

RESULTS

In 12Z cells, GSI treatment reduced aldehyde dehydrogenase activity and colony formation, and induced a shift to the G2/M phase of the cell cycle. Cell viability was decreased and apoptosis was increased in both cell models. GSI further induced transcriptional downregulation of the stemness-associated factors leukemia inhibitory factor receptor (LIFR), sex-determining region Y (SRY)- box 2, interferon-induced transmembrane protein 1, and hes-related family bHLH transcription factor with YRPW motif 1, in 12Z cells and in primary cell cultures. Downregulation of LIFR expression by GSI was confirmed at the protein level by flow cytometry.

CONCLUSIONS

Our in vitro data suggest that application of GSI may be a worthwhile approach in the treatment of endometriosis that warrants further investigation.

Uterine stem cells: from basic research to advanced cell therapies

BACKGROUND

Stem cell research in the endometrium and myometrium from animal models and humans has led to the identification of endometrial/myometrial stem cells and their niches. This basic knowledge is beginning to be translated to clinical use for incurable uterine pathologies. Additionally, the implication of bone marrow-derived stem cells (BMDSCs) in uterine physiology has opened the field for the exploration of an exogenous and autologous source of stem cells.

OBJECTIVE AND RATIONALE

In this review, we outline the progress of endometrial and myometrial stem/progenitor cells in both human and mouse models from their characterization to their clinical application, indicating roles in Asherman syndrome, atrophic endometrium and tissue engineering, among others.

SEARCH METHODS

A comprehensive search of PubMed and Google Scholar up to December 2017 was conducted to identify peer-reviewed literature related to the contribution of bone marrow, endometrial and myometrial stem cells to potential physiological regeneration as well as their implications in pathologies of the human uterus.

OUTCOMES

The discovery and main characteristics of stem cells in the murine and human endometrium and myometrium are presented together with the relevance of their niches and cross-regulation. The current state of advanced stem cell therapy using BMDSCs in the treatment of Asherman syndrome and atrophic endometrium is analyzed. In the myometrium, the understanding of genetic and epigenetic defects that result in the development of tumor-initiating cells in the myometrial stem niche and thus contribute to the growth of uterine leiomyoma is also presented. Finally, recent advances in tissue engineering based on the creation of novel three-dimensional scaffolds or decellularisation open up new perspectives for the field of uterine transplantation.

WIDER IMPLICATIONS

More than a decade after their discovery, the knowledge of uterine stem cells and their niches is crystalising into novel therapeutic approaches aiming to treat with cells those conditions that cannot be cured with drugs, particularly the currently incurable uterine pathologies. Additional work and improvements are needed, but the basis has been formed for this therapeutic application of uterine cells.

Therapeutic strategies involving uterine stem cells in reproductive medicine

PURPOSE OF REVIEW

The current review provides an update on recent advances in stem cell biology relevant to female reproduction.

RECENT FINDINGS

Stem cells are undifferentiated cells that often serve as a reservoir of cells to regenerate tissue in settings or injury or cell loss. The endometrium has progenitor stem cells that can replace all of the endometrium during each menstrual cycle. In addition, multipotent endometrial cells replace these progenitor cells when depleted. Recruitment of stem cells from outside of the uterus occurs in setting of increased demand such as ischemia or injury. Bone marrow-derived multipotent stem cells are recruited to the uterus by estrogen or injury-induced expression of the chemokine CXCL12. In the setting of overwhelming injury, especially in the setting of low estrogen levels, there may be insufficient stem cell recruitment to adequately repair the uterus resulting in conditions such as Asherman syndrome or other endometrial defects. In contrast, excessive recruitment of stem cells underlies endometriosis. Enhanced understanding of stem-cell mobilization, recruitment, and engraftment has created the possibility of improved therapy for endometrial defects and endometriosis through enhanced manipulation of stem-cell trafficking. Further, the normal endometrium is a rich source of multipotent stem cells that can be used for numerous applications in regenerative medicine beyond reproduction.

SUMMARY

A better understanding of reproductive stem-cell biology may allow improved treatment of endometrial disease such as Asherman syndrome and other endometrial receptivity defects. Inhibiting stem-cell mobilization may also be helpful in endometriosis therapy. Finally, endometrial derived multipotent stem cells may play a crucial role in cell therapy for regenerative medicine.

Sources and Clinical Applications of Mesenchymal Stem Cells: State-of-the-art review

First discovered by Friedenstein in 1976, mesenchymal stem cells (MSCs) are adult stem cells found throughout the body that share a fixed set of characteristics. Discovered initially in the bone marrow, this cell source is considered the gold standard for clinical research, although various other sources-including adipose tissue, dental pulp, mobilised peripheral blood and birth-derived tissues-have since been identified. Although similar, MSCs derived from different sources possess distinct characteristics, advantages and disadvantages, including their differentiation potential and proliferation capacity, which influence their applicability. Hence, they may be used for specific clinical applications in the fields of regenerative medicine and tissue engineering. This review article summarises current knowledge regarding the various sources, characteristics and therapeutic applications of MSCs.

Endometrial Stem Cell Markers: Current Concepts and Unresolved Questions

The human endometrium is a highly regenerative organ undergoing over 400 cycles of shedding and regeneration over a woman’s lifetime. Menstrual shedding and the subsequent repair of the functional layer of the endometrium is a process unique to humans and higher-order primates. This massive regenerative capacity is thought to have a stem cell basis, with human endometrial stromal stem cells having already been extensively studied. Studies on endometrial epithelial stem cells are sparse, and the current belief is that the endometrial epithelial stem cells reside in the terminal ends of the basalis glands at the endometrial/myometrial interface. Since almost all endometrial pathologies are thought to originate from aberrations in stem cells that regularly regenerate the functionalis layer, expansion of our current understanding of stem cells is necessary in order for curative treatment strategies to be developed. This review critically appraises the postulated markers in order to identify endometrial stem cells. It also examines the current evidence supporting the existence of epithelial stem cells in the human endometrium that are likely to be involved both in glandular regeneration and in the pathogenesis of endometrial proliferative diseases such as endometriosis and endometrial cancer.

The immunomodulatory activity of extracellular vesicles derived from endometrial mesenchymal stem cells on CD4+ T cells is partially mediated by TGFbeta

Endometrial mesenchymal stem cells (endMSCs) reside in the basal and functional layer of human endometrium and participate in tissue remodelling, which is required for maintaining the regenerative capacity of the endometrium. The endMSCs are multipotent stem cells and exhibit immunomodulatory effects. This paper aimed to evaluate the regulatory effects of extracellular vesicles derived from endMSCs (EV-endMSCs) in the setting of T cell activation. In vitro stimulations of lymphocytes were performed in the presence of EV-endMSCs. These in vitro-stimulated lymphocytes were functionally and phenotypically characterized to distinguish CD4+ and CD8+ T cell differentiation subsets. Moreover, the inhibition of TGFβ was performed with neutralizing antibodies. The phenotype and nanoparticle tracking analysis of the EV-endMSCs demonstrated that they are similar in terms of size distribution to other mesenchymal stem cells-derived exosomes. The in vitro assays showed an immunomodulatory potential of these vesicles to counteract the differentiation of CD4+ T cells. The quantification of active TGFβ in EV-endMSCs was found to be very high when compared with extracellular vesicles-free concentrated supernatants. Finally, the neutralization of TGFβ significantly attenuated the immunomodulatory activity of EV-endMSCs. In summary, this is the first report demonstrating that EV-endMSCs exhibit a potent inhibitory effect against CD4+ T cell activation, which is partially mediated by TGFβ signalling.

The Fate of Autologous Endometrial Mesenchymal Stromal Cells After Application in the Healthy Equine Uterus

Because of their distinct differentiation, immunomodulatory, and migratory capacities, endometrial mesenchymal stromal cells (MSCs) may provide an optimum source of therapeutic cells not only in relation to the uterus but also for regeneration of other tissues. This study reports the fate of endometrial MSCs following intrauterine application in mares. Stromal cell fractions were isolated from endometrial biopsies taken from seven reproductively healthy mares, expanded, and fluorescence labeled in culture. Phosphate-buffered saline (PBS) or MSCs (15 × 10⁶) were autologously infused into each uterine horn during early diestrus and subsequently tracked by fluorescence microscopy and flow cytometry of endometrial biopsies and blood samples taken periodically after infusion. The inflammatory response to cell infusion was monitored in endometrial cytology samples. MSCs were detected in endometrial sections at 6, 12, and 24 h, but not later (7 or 14 days), after cell infusion. Cells were in all cases located in the uterine lumen, never within the endometrial tissue. No fluorescence signal was detected in blood samples at any time point after infusion. Cytology analyses showed an increase in % of polymorphonuclear neutrophils between 1 and 3 h after uterine infusion with either MSCs or PBS and a further increase by 6 h only in mares infused with PBS. In summary, endometrial MSCs were detected in the uterine lumen for up to 24 h after infusion, but did not migrate into the healthy endometrium. Moreover, MSCs effectively attenuated the inflammatory response to uterine infusion. We conclude that endometrial MSCs obtained from routine uterine biopsies could provide a safe and effective cell source for treatment of inflammatory conditions of the uterus and potentially other tissues.

The endometrial stem cell markers notch-1 and numb are associated with endometriosis

Previous studies reported increased expression of the notch pathway-associated protein Musashi-1 in endometriosis. This case-control study investigates an association of the endometrial stem cell markers notch-1 and numb with endometriosis. Fifty-one endometriosis patients and 76 controls were recruited in the IVF unit and tertiary endometriosis referral centre of a university hospital. All subjects underwent transcervical endometrial biopsy and diagnostic laparoscopy. Expression of endometrial notch-1 and numb was assessed by immunostaining and correlated with clinical data. Association of stem-cell-marker expression with the presence of endometriosis was evaluated. Numb expression in the luminal epithelium was significantly higher in eutopic endometrium of endometriosis patients compared with controls (20.5% versus 16.5%, P = 0.033). Numb-positive single stromal cells were less frequent in endometrioma patients compared with other forms of endometriosis (0.3 versus 0.5 cells/visual field; P = 0.028). Notch-1 expression in endometrial glands was significantly higher in patients with deep infiltrating endometriosis compared with controls (39.1% versus 21.8%; P = 0.045). We conclude that stem cell markers notch-1 and numb of eutopic endometrium are associated with endometriosis and its clinical presentations, supporting the stem cell hypothesis of endometriosis. These findings could help develop promising research strategies applying endometrial stem cells as novel tools.

Mesenchymal endometrial stem/stromal cells for hard tissue engineering: a review of in vitro and in vivo evidence

Hard tissues including teeth, bone and cartilage have inability or poor capacity to self-renew, especially in large defects. Therefore, repair of damages in these tissues represents a huge challenge in the medical field today. Hard tissue engineering commonly utilizes different stem cell sources as a promising strategy for treating bone, cartilages and tooth defects or disorders. Decades ago, researchers successfully isolated and identified endometrial mesenchymal stem/stromal cells (EnSCs) and discovered their multidifferentiation potential. Current studies suggest that EnSCs have significant advantages compared with stem cells derived from other tissues. In this review article, we summarize the current in vitro and in vivo studies that utilize EnSCs or menstrual blood-derived stem cells for differentiation to osteoblasts, odontoblasts or chondroblasts in an effort to realize the potential of these cells in hard tissues regeneration.

Cytotherapy using stromal cells: Current and advance multi-treatment approaches

The research in stem cells gives a proper information about basic mechanisms of human development and differentiation. The use of stem cells in new medicinal therapies includes treatment of different conditions such as spinal cord injury, diabetes mellitus, Parkinsonism, and cardiac disorders. These cells exhibit two unique properties: self-renewal and differentiation. The major stem cells been used for approximately about 10-14 years for cellular therapy are mesenchymal stem cells. Mesenchymal stem cells can individualize into many lineage, i.e. into both mesenchymal and non-mesenchymal lineage, such as into osteoblasts, chondrocytes, myocytes, adipocytes, neurons, etc. This review focuses on the history, types of stem cells and their targets and mechanisms of mesenchymal stem cells. Mesenchymal stem cells are the significant futuristic carrier for treating diseases associated not only with regeneration but also immunomodulation.

Isolation and characterization of equine endometrial mesenchymal stromal cells

Background

Equine mesenchymal stromal/stem cells (MSCs) are most commonly harvested from bone marrow (BM) or adipose tissue, requiring the use of surgical procedures. By contrast, the uterus can be accessed nonsurgically, and may provide a more readily available cell source. While human endometrium is known to harbor mesenchymal precursor cells, MSCs have not been identified in equine endometrium. This study reports the isolation, culture, and characterization of MSCs from equine endometrium.

Methods

The presence of MSC and pericyte markers in endometrial sections was determined using immunohistochemistry. Stromal cells were harvested and cultured after separation of epithelial cells from endometrial fragments using Mucin-1-bound beads. For comparison, MSCs were also harvested from BM. The expression of surface markers in endometrial and BM-derived MSCs was characterized using flow cytometry and quantitative polymerase chain reaction. MSCs were differentiated in vitro into adipogenic, chondrogenic, osteogenic, and smooth muscle lineages.

Results

Typical markers of MSCs (CD29, CD44, CD90, and CD105) and pericytes (NG2 and CD146) were localized in the equine endometrium. Both endometrial and BM MSCs grew clonally and robustly expressed MSC and pericyte markers in culture while showing greatly reduced or negligible expression of hematopoietic markers (CD45, CD34) and MHC-II. Additionally, both endometrial and BM MSCs differentiated into adipogenic, osteogenic, and chondrogenic lineages in vitro, and endometrial MSCs had a distinct ability to undergo smooth muscle differentiation.

Conclusions

We have demonstrated for the first time the presence of cells in equine endometrium that fulfill the definition of MSCs. The equine endometrium may provide an alternative, easily accessible source of MSCs, not only for therapeutic regeneration of the uterus, but also for other tissues where MSCs from other sources are currently being used therapeutically.

Oleic acid promotes the expression of neural markers in differentiated human endometrial stem cells

Variety of neurodegenerative diseases in humans are caused by loss of cells along with loss of function and disability. Cell replacement therapy is a potential strategy to cure neurodegenerative diseases. Mesenchymal stem cells are pluripotent non-hematopoietic cells that can be isolated from numerous tissues. Human endometrial-derived stem cell (hEnSC) are the abundant and easy available source with no immunological response, for cell replacement therapy. In the nervous system, where fatty acids are found in huge amounts, they participate in its development and maintenance throughout life. Oleic acid is a kind of the saturated fatty acids which plays crucial role in brain development. Oleic acid released by astrocytes is used by neurons for the synthesis of phospholipids and is specifically incorporated into growth cones. Human endometrial-derived stem cells in the third passage were divided into 3 groups including: control, sham (cultured in full differentiation medium without oleic acid) and experimental group (cultured in full differentiation medium with oleic acid) to differentiate over a 18-day period. Data from Real-Time PCR showed that mRNA levels of NF and β-TUBULIN were increased significantly (p<0.05) in oleic acid treated cells in comparison to control and sham groups. Immunocytochemistry analysis of Chat and NF expression also showed the same results. The present study clearly demonstrates that oleic acid promotes neural differentiation of hEnSC through regulation of gene expression.

Successful derivation of xeno-free mesenchymal stem cell lines from endometrium of infertile women

Transplantation of mesenchymal stem cells (MSC) can effectively repair endometrial deficiencies, including infertile patients with a problem of inadequate endometrium thickness. Although, MSC derived from different organ sources have a similarity of MSC specific characteristics, endometrial stem cells (EMSC) are temporally regulated throughout the menstrual cycle in a micro-environmental niche found only in endometrial tissue. Given the micro-environment niche, developing treatments for endometrial disorders with EMSC should be a top priority. To provide EMSC that afford safety for therapeutic usage, we have established a completely xeno-free EMSC line derivation protocol using human allogenic umbilical cord serum instead of animal derived reagents, and proved that it is feasible to generate xeno-free EMSC lines from infertile patient donors using these conditions. Our results demonstrate the successful derivation of xeno-free EMSC lines from 10 out of 10 infertile patients. The resultant xeno-free EMSC lines showed typical MSC morphology, phenotypic markers, differentiation capacity, telomere length and normal karyotypes. They showed superior proliferation capability, but lower expression of proto-oncogenes, to the lines generated under standard (animal derived reagents) culture. Biosafety of xeno-free EMSC lines also displayed in retention of immunosuppressive ability, epigenetic stability by imprinted genes expression, proto-oncogenes expression and no mutation of specific codon on p53 tumor suppressor gene. Taken together, these data indicate that our cells may be safe for clinical use. In conclusion, we have succeeded in establishing completely xeno-free EMSC lines and demonstrate for the first time that autogenic and xeno-free EMSC lines can be generated from infertile women.

Mesenchymal Stem Cells Subpopulations: Application for Orthopedic Regenerative Medicine

Research on mesenchymal stem cells (MSCs) continues to progress rapidly. Nevertheless, the field faces several challenges, such as inherent cell heterogeneity and the absence of unique MSCs markers. Due to MSCs' ability to differentiate into multiple tissues, these cells represent a promising tool for new cell-based therapies. However, for tissue engineering applications, it is critical to start with a well-defined cell population. Additionally, evidence that MSCs subpopulations may also feature distinct characteristics and regeneration potential has arisen. In this report, we present an overview of the identification of MSCs based on the expression of several surface markers and their current tissue sources. We review the use of MSCs subpopulations in recent years and the main methodologies that have addressed their isolation, and we emphasize the most-used surface markers for selection, isolation, and characterization. Next, we discuss the osteogenic and chondrogenic differentiation from MSCs subpopulations. We conclude that MSCs subpopulation selection is not a minor concern because each subpopulation has particular potential for promoting the differentiation into osteoblasts and chondrocytes. The accurate selection of the subpopulation advances possibilities suitable for preclinical and clinical studies and determines the safest and most efficacious regeneration process.

Endometrial mesenchymal stem cells as a cell based therapy for pelvic organ prolapse

Pelvic organ prolapse (POP) occurs when the pelvic organs (bladder, bowel or uterus) herniate into the vagina, causing incontinence, voiding, bowel and sexual dysfunction, negatively impacting upon a woman’s quality of life. POP affects 25% of all women and results from childbirth injury. For 19% of all women, surgical reconstructive surgery is required for treatment, often augmented with surgical mesh. The surgical treatment fails in up to 30% of cases or results in adverse effects, such as pain and mesh erosion into the bladder, bowel or vagina. Due to these complications the Food and Drug Administration cautioned against the use of vaginal mesh and several major brands have been recently been withdrawn from market. In this review we will discuss new cell-based approaches being developed for the treatment of POP. Several cell types have been investigated in animal models, including a new source of mesenchymal stem/stromal cells (MSC) derived from human endometrium. The unique characteristics of endometrial MSC, methods for their isolation and purification and steps towards their development for good manufacturing practice production will be described. Animal models that could be used to examine the potential for this approach will also be discussed as will a rodent model showing promise in developing an endometrial MSC-based therapy for POP. The development of a preclinical large animal model for assessing tissue engineering constructs for treating POP will also be mentioned.

Regenerative Therapy of Type 1 Diabetes Mellitus: From Pancreatic Islet Transplantation to Mesenchymal Stem Cells

Type 1 diabetes is an autoimmune disease resulting in the permanent destruction of pancreatic islets. Islet transplantation to portal vein provides an approach to compensate for loss of insulin producing cells. Clinical trials demonstrated that even partial islet graft function reduces severe hypoglycemic events in patients. However, therapeutic impact is restrained due to shortage of pancreas organ donors and instant inflammation occurring in the hepatic environment of the graft. We summarize on what is known about regenerative therapy in type 1 diabetes focusing on pancreatic islet transplantation and new avenues of cell substitution. Metabolic pathways and energy production of transplanted cells are required to be balanced and protection from inflammation in their intravascular bed is desired. Mesenchymal stem cells (MSCs) have anti-inflammatory features, and so they are interesting as a therapy for type 1 diabetes. Recently, they were reported to reduce hyperglycemia in diabetic rodents, and they were even discussed as being turned into endodermal or pancreatic progenitor cells. MSCs are recognized to meet the demand of an individual therapy not raising the concerns of embryonic or induced pluripotent stem cells for therapy.