Adult stem cells in the endometrium

Receptivity markers in endometrial mesenchymal stem cells of recurrent implantation failure and non-recurrent implantation failure women: A pilot study

AIM

Endometrial mesenchymal stem cells (eMSC) have a vital role in regeneration of endometrium during menstrual cycles. Since it has been suggested that (eMSC) likely play a role in uterine receptivity and establishment of pregnancy, we aimed to evaluate the expression levels of five most known receptivity markers-Integrin (ITG) β1, Rac1, HoxA11, ITGβ3 and Noggin-in eMSC of recurrent implantation failure (RIF) and non-RIF women.

METHODS

Human eMSC were isolated from menstrual blood (MB) of RIF and non-RIF women. The isolated eMSC characterized based on their morphological and behavioral characteristics, expression of MSC-specific surface CD markers and their capacity of differentiation into osteocytes and adipocytes. The expression levels of the five mentioned receptivity markers were analyzed with real time reverse transcription polymerase chain reaction.

RESULTS

Our findings revealed that RIF and non-RIF eMSC expressed all tested genes at different levels. ITGb1 expression in RIF eMSC was lower than its expression in non-RIF cells. On the other hand, all the other markers were expressed at higher levels in RIF eMSC than in non-RIF cells although only HOXA11 and ITG β3 showed statistically significant (P < 0.05) higher expression levels.

CONCLUSION

This pilot study on determination of the expression levels of uterine receptivity markers in eMSC interestingly indicated that RIF and non-RIF eMSC were different regarding the expression of these markers. Future studies using these findings can brighten up more the role of eMSC in the endometrium receptivity and establishment of pregnancy.

Endometriosis and nuclear receptors

BACKGROUND

Endometriosis is recognized as a steroid-dependent disorder; however, the precise roles of nuclear receptors (NRs) in steroid responsiveness and other signaling pathways are not well understood.

OBJECTIVE AND RATIONALE

Over the past several years, a number of paradigm-shifting breakthroughs have occurred in the area of NRs in endometriosis. We review and clarify new information regarding the mechanisms responsible for: (i) excessive estrogen biosynthesis, (ii) estrogen-dependent inflammation, (iii) defective differentiation due to progesterone resistance and (iv) enhanced survival due to deficient retinoid production and action in endometriosis. We emphasize the roles of the relevant NRs critical for these pathological processes in endometriosis.

SEARCH METHODS

We conducted a comprehensive search using PubMed for human, animal and cellular studies published until 2018 in the following areas: endometriosis; the steroid and orphan NRs, estrogen receptors alpha (ESR1) and beta (ESR2), progesterone receptor (PGR), steroidogenic factor-1 (NR5A1) and chicken ovalbumin upstream promoter-transcription factor II (NR2F2); and retinoids.

OUTCOMES

Four distinct abnormalities in the intracavitary endometrium and extra-uterine endometriotic tissue underlie endometriosis progression: dysregulated differentiation of endometrial mesenchymal cells, abnormal epigenetic marks, inflammation activated by excess estrogen and the development of progesterone resistance. Endometriotic stromal cells compose the bulk of the lesions and demonstrate widespread epigenetic abnormalities. Endometriotic stromal cells also display a wide range of abnormal NR expression. The orphan NRs NR5A1 and NR2F2 compete to regulate steroid-synthesizing genes in endometriotic stromal cells; NR5A1 dominance gives rise to excessive estrogen formation. Endometriotic stromal cells show an abnormally low ESR1:ESR2 ratio due to excessive levels of ESR2, which mediates an estrogen-driven inflammatory process and prostaglandin formation. These cells are also deficient in PGR, leading to progesterone resistance and defective retinoid synthesis. The pattern of NR expression, involving low ESR1 and PGR and high ESR2, is reminiscent of uterine leiomyoma stem cells. This led us to speculate that endometriotic stromal cells may display stem cell characteristics found in other uterine tissues. The biologic consequences of these abnormalities in endometriotic tissue include intense inflammation, defective differentiation and enhanced survival.

WIDER IMPLICATIONS

Steroid- and other NR-related abnormalities exert genome-wide biologic effects via interaction with defective epigenetic programming and enhance inflammation in endometriotic stromal cells. New synthetic ligands, targeting PGR, retinoic acid receptors and ESR2, may offer novel treatment options.

Menstrual blood-derived stem cells: toward therapeutic mechanisms, novel strategies, and future perspectives in the treatment of diseases

Menstrual blood-derived stem cells (MenSCs) have great potential in the treatment of various diseases. As a novel type of mesenchymal stem cells (MSCs), MenSCs have attracted more interest due to their therapeutic effects in both animal models and clinical trials. Here, we described the differentiation, immunomodulation, paracrine, homing, and engraftment mechanisms of MenSCs. These include differentiation into targeting cells, immunomodulation with various immune cells, the paracrine effect on secreting cytokines, and homing and engraftment into injured sites. To better conduct MenSC-based therapy, some novel hotspots were proposed such as CRISPR (clustered regularly interspaced short palindromic repeats)/cas9-mediated gene modification, exosomes for cell-free therapy, single-cell RNA sequence for precision medicine, engineered MenSC-based therapy for the delivery platform, and stem cell niches for improving microenvironment. Subsequently, current challenges were elaborated on, with regard to age of donor, dose of MenSCs, transplantation route, and monitoring time. The management of clinical research with respect to MenSC-based therapy in diseases will become more normative and strict. Thus, a more comprehensive horizon should be considered that includes a combination of traditional solutions and novel strategies. In summary, MenSC-based treatment has a great potential in treating diseases through diverse strategies, and more therapeutic mechanisms and novel strategies need to be elucidated for future regenerative medicine and clinical applications.

The Pathogenesis of Endometriosis: Molecular and Cell Biology Insights

The etiopathogenesis of endometriosis is a multifactorial process resulting in a heterogeneous disease. Considering that endometriosis etiology and pathogenesis are still far from being fully elucidated, the current review aims to offer a comprehensive summary of the available evidence. We performed a narrative review synthesizing the findings of the English literature retrieved from computerized databases from inception to June 2019, using the Medical Subject Headings (MeSH) unique ID term “Endometriosis” (ID:D004715) with “Etiology” (ID:Q000209), “Immunology” (ID:Q000276), “Genetics” (ID:D005823) and “Epigenesis, Genetic” (ID:D044127). Endometriosis may origin from Müllerian or non-Müllerian stem cells including those from the endometrial basal layer, Müllerian remnants, bone marrow, or the peritoneum. The innate ability of endometrial stem cells to regenerate cyclically seems to play a key role, as well as the dysregulated hormonal pathways. The presence of such cells in the peritoneal cavity and what leads to the development of endometriosis is a complex process with a large number of interconnected factors, potentially both inherited and acquired. Genetic predisposition is complex and related to the combined action of several genes with limited influence. The epigenetic mechanisms control many of the processes involved in the immunologic, immunohistochemical, histological, and biological aberrations that characterize the eutopic and ectopic endometrium in affected patients. However, what triggers such alterations is not clear and may be both genetically and epigenetically inherited, or it may be acquired by the particular combination of several elements such as the persistent peritoneal menstrual reflux as well as exogenous factors. The heterogeneity of endometriosis and the different contexts in which it develops suggest that a single etiopathogenetic model is not sufficient to explain its complex pathobiology.

Myometrial Cells Stimulate Self-Renewal of Endometrial Mesenchymal Stem-Like Cells Through WNT5A/β-Catenin Signaling

Human endometrium undergoes cycles of proliferation and differentiation throughout the reproductive years of women. The endometrial stem/progenitor cells contribute to this regenerative process. They lie in the basalis layer of the endometrium next to the myometrium. We hypothesized that human myometrial cells provide niche signals regulating the activities of endometrial mesenchymal stem-like cells (eMSCs). In vitro coculture of myometrial cells enhanced the colony-forming and self-renewal ability of eMSCs. The cocultured eMSCs retained their multipotent characteristic and exhibited a greater total cell output when compared with medium alone culture. The expression of active β-catenin in eMSCs increased significantly after coculture with myometrial cells, suggesting activation of WNT/β-catenin signaling. Secretory factors in spent medium from myometrial cell culture produced the same stimulatory effects on eMSCs. The involvement of WNT/β-catenin signaling in self-renewal of eMSCs was confirmed with the use of WNT activator (Wnt3A conditioned medium) and WNT inhibitors (XAV939 and inhibitor of Wnt Production-2 [IWP-2]). The myometrial cells expressed more WNT5A than other WNT ligands. Recombinant WNT5A stimulated whereas anti-WNT5A antibody suppressed the colony formation, self-renewal, and T-cell factor/lymphoid enhancer-binding factor (TCF/LEF) transcriptional activities of eMSCs. Moreover, eMSCs expressed FZD4 and LRP5. WNT5A is known to activate the canonical WNT signaling in the presence of these receptor components. WNT antagonist, DKK1, binds to LRP5/6. Consistently, DKK1 treatment nullified the stimulatory effect of myometrial cell coculture. In conclusion, our findings show that the myometrial cells are niche components of eMSCs, modulating the self-renewal activity of eMSCs by WNT5A-dependent activation of WNT/β-catenin signaling. Stem Cells 2019;37:1455-1466.

A collagen scaffold loaded with human umbilical cord-derived mesenchymal stem cells facilitates endometrial regeneration and restores fertility

In women of reproductive age, severe injuries to the endometrium are often accompanied by endometrial scar formation or intrauterine adhesions (IUAs), which can result in infertility or miscarriage. Although many approaches have been used to treat severe IUAs, high recurrence rates and endometrial thinning have limited therapeutic efficiency. In this study, a collagen scaffold (CS) loaded with human umbilical cord-derived mesenchymal stem cells (UC-MSCs) was fabricated and applied for endometrial regeneration. The CS/UC-MSCs promoted human endometrial stromal cell proliferation and inhibited apoptosis in vitro through paracrine effects. In a model of endometrial damage, transplantation with the CS/UC-MSCs maintained normal luminal structure, promoted endometrial regeneration and collagen remodeling, induced intrinsic endometrial cell proliferation and epithelium recovery, and enhanced the expression of estrogen receptor α and progesterone receptor. An improved ability of the regenerated endometrium to receive embryos was confirmed. Together, our results indicate that the CS/UC-MSCs promoted endometrial structural reconstruction and functional recovery. Topical administration of the CS/UC-MSCs after trans-cervical resection of adhesions might prevent re-adhesion, promote endometrium regeneration and improve pregnancy outcomes for patients with severe IUAs. STATEMENT OF SIGNIFICANCE: Intrauterine adhesions due to severe endometrium injuries happen frequently in clinic and become one of the crucial reasons for women's infertility or miscarriage. Therefore, how to regenerate the damaged endometrium is a big challenge. In this study, a collagen scaffold (CS) loaded with human umbilical cord-derived mesenchymal stem cells (UC-MSCs) was fabricated and applied for endometrium regeneration. Herein, UC-MSCs, known for low immunogenicity and high proliferative potential, exhibit promising potential for endometrium regeneration; and collagen scaffolds provide suitable physical support. It was proved that transplantation with CS/UC-MSCs promoted endometrial regeneration and fertility restoration. It suggested that topical administration of CS/UC-MSCs in uterus could be a promising strategy for patients suffering severe intrauterine adhesion and infertility.

Hormonal oral contraceptive influence on isolation, Characterization and cryopreservation of mesenchymal stem cells from menstrual fluid

The purpose of the study was to evaluate whether the intake of hormonal oral contraceptive influences the viability of mesenchymal stem cell. Sixteen healthy female volunteers with regular menstrual cycles were invited to participate. Menstrual fluid was collected on the day of maximum flux, and collected cells were analyzed by a 'minimal standard' for MSC characterization: plastic adherence, trilineage (adipogenic, osteogenic, chondrogenic) in vitro differentiation and a minimalistic panel of markers assessed by flow cytometry (CD731, CD901, CD1051, CD34-, CD45-) using monoclonal antibodies. The participants were divided into two groups: Group 1 - no hormonal contraceptive use; Group 2 - hormonal oral contraceptive use. The median of the menstrual fluid volume was 5.0 and the median number of cells was 5.2 × 10⁶. Median of cell viability was 89.3%. After culture, mesenchymal stem cells increased from 0.031% of the total cells to 96.9%. The cells formed clusters and reached confluence after 15-21 days of culture in the first passage. In the second passage, clusters and the confluence were observed after 3 days of culture. No difference was observed between the groups. Our data suggest that oral hormonal contraceptive intake maintains the viability of mesenchymal stem cells from menstrual fluid.

Endometriotic Peritoneal Fluid Promotes Myofibroblast Differentiation of Endometrial Mesenchymal Stem Cells

During the development of endometriosis, the presence of fibrotic tissues in and surrounding endometriotic lesions may lead to subsequent adhesion, anatomic distortion, and chronic pain. Therefore, studies aimed at clarifying the underlying mechanisms of fibrogenesis in endometriosis could potentially provide a novel strategy for effective treatment. Mesenchymal stem cells (MSCs) play a key role in fibrotic diseases by differentiating into myofibroblasts in appropriate microenvironment. In this study, we collected endometrial and endometriotic tissues from patients with endometriosis (n = 32) and control patients without endometriosis (n = 20) to compare the expression of fibrotic proteins and investigate the effect of endometriotic peritoneal fluid (PF) on myofibroblast differentiation of endometrial MSCs. We found that the expression of fibrotic proteins, including alpha-smooth muscle actin (α-SMA), type I collagen (collagen I), connective tissue growth factor (CTGF), and fibronectin, and the extent of fibrosis extremely enhanced in ectopic endometria compared with eutopic endometria from the same patients with endometriosis and normal endometria from patients without endometriosis. We next isolated and identified endometrial MSCs and found that treatment with endometriotic PF strongly induced endometrial MSCs to differentiate into myofibroblasts concomitant with the activation of Smad2/3. Moreover, ectopic endometrial MSCs expressed elevated collagen I, α-SMA, fibronectin, and CTGF. Sushi domain containing-2 (SUSD2), a marker of endometrial MSCs, and α-SMA, a well-recognized marker for myofibroblasts, colocalized extensively in ectopic endometria while seldom in normal and eutopic endometria. These findings suggest that ectopic endometrial MSCs are probably more susceptible to myofibroblast differentiation because of the long-term influence of endometriotic PF. All together, we report for the first time that endometriotic PF promotes myofibroblast differentiation of endometrial MSCs. This understanding will greatly improve our understanding of the pathophysiology of endometriosis and help design better therapeutics.

Anti-inflammatory cytokines in endometriosis

Although the pathogenesis of endometriosis is not fully understood, it is often considered to be an inflammatory disease. An increasing number of studies suggest that differential expression of anti-inflammatory cytokines (e.g., interleukin-4 and -10, and transforming growth factor-β1) occurs in women with endometriosis, including in serum, peritoneal fluid and ectopic lesions. These anti-inflammatory cytokines also have indispensable roles in the progression of endometriosis, including by promoting survival, growth, invasion, differentiation, angiogenesis, and immune escape of the endometriotic lesions. In this review, we provide an overview of the expression, origin, function and regulation of anti-inflammatory cytokines in endometriosis, with brief discussion and perspectives on their future clinical implications in the diagnosis and therapy of the disease.

The ectonucleoside triphosphate diphosphohydrolase-2 (NTPDase2) in human endometrium: a novel marker of basal stroma and mesenchymal stem cells

The human endometrium undergoes repetitive regeneration cycles in order to recover the functional layer, shed during menses. The basal layer, which remains in charge of endometrial regeneration in every cycle, contains adult stem or progenitor cells of epithelial and mesenchymal lineage. Some pathologies such as adenomyosis, in which endometrial tissue develops within the myometrium, originate from this layer. It is well known that the balance between adenosine triphosphate (ATP) and adenosine plays a crucial role in stem/progenitor cell physiology, influencing proliferation, differentiation, and migration. The extracellular levels of nucleotides and nucleosides are regulated by the ectonucleotidases, such as the nucleoside triphosphate diphosphohydrolase 2 (NTPDase2). NTPDase2 is a membrane-expressed enzyme found in cells of mesenchymal origin such as perivascular cells of different tissues and the stem cells of adult neurogenic regions. The aim of this study was to characterize the expression of NTPDase2 in human nonpathological cyclic and postmenopausic endometria and in adenomyosis. We examined proliferative, secretory, and atrophic endometria from women without endometrial pathology and also adenomyotic lesions. Importantly, we identified NTPDase2 as the first marker of basal endometrium since other stromal cell markers such as CD10 label the entire stroma. As expected, NTPDase2 was also found in adenomyotic stroma, thus becoming a convenient tracer of these lesions. We did not record any changes in the expression levels or the localization of NTPDase2 along the cycle, thus suggesting that the enzyme is not influenced by the female sex hormones like other previously studied ectoenzymes. Remarkably, NTPDase2 was expressed by the Sushi Domain containing 2 (SUSD2)⁺ endometrial mesenchymal stem cells (eMSCs) found perivascularly, rendering it useful as a cell marker to improve the isolation of eMSCs needed for regenerative medicine therapies.

Therapeutic potential of menstrual blood-derived endometrial stem cells in cardiac diseases

Despite significant developments in medical and surgical strategies, cardiac diseases remain the leading causes of morbidity and mortality worldwide. Numerous studies involving preclinical and clinical trials have confirmed that stem cell transplantation can help improve cardiac function and regenerate damaged cardiac tissue, and stem cells isolated from bone marrow, heart tissue, adipose tissue and umbilical cord are the primary candidates for transplantation. During the past decade, menstrual blood-derived endometrial stem cells (MenSCs) have gradually become a promising alternative for stem cell-based therapy due to their comprehensive advantages, which include their ability to be periodically and non-invasively collected, their abundant source material, their ability to be regularly donated, their superior proliferative capacity and their ability to be used for autologous transplantation. MenSCs have shown positive therapeutic potential for the treatment of various diseases. Therefore, aside from a brief introduction of the biological characteristics of MenSCs, this review focuses on the progress being made in evaluating the functional improvement of damaged cardiac tissue after MenSC transplantation through preclinical and clinical studies. Based on published reports, we conclude that the paracrine effect, transdifferentiation and immunomodulation by MenSC promote both regeneration of damaged myocardium and improvement of cardiac function.

Repair of Osteochondral Defects in Rabbit Knee Using Menstrual Blood Stem Cells Encapsulated in Fibrin Glue: A Good Stem Cell Candidate for the Treatment of Osteochondral Defects

Background

In recent years, researchers discovered that menstrual blood-derived stem cells (MenSCs) have the potential to differentiate into a wide range of tissues including the chondrogenic lineage. In this study, we aimed to investigate the effect of MenSCs encapsulated in fibrin glue (FG) on healing of osteochondral defect in rabbit model.

Methods

We examined the effectiveness of MenSCs encapsulated in FG in comparison with FG alone in the repair of osteochondral defect (OCD) lesions of rabbit knees after 12 and 24 weeks.

Results

Macroscopical evaluation revealed that the effectiveness of MenSCs incorporation with FG is much higher than FG alone in repair of OCD defects. Indeed, histopathological evaluation of FG + MenSCs group at 12 weeks post-transplantation demonstrated that defects were filled with hyaline cartilage-like tissue with proper integration, high content of glycosaminoglycan and the existence of collagen fibers especially collagen type II, as well as by passing time (24 weeks post-transplantation), the most regenerated tissue in FG + MenSCs group was similar to hyaline cartilage with relatively good infill and integration. As the same with the result of 12 weeks post-implantation, the total point of microscopical examination in FG + MenSCs group was higher than other experimental groups, however, no significant difference was detected between groups at 24 weeks (p > 0.05).

Conclusion

In summary, MenSCs as unique stem cell population, is suitable for in vivo repair of OCD defects and promising for the future clinical application.

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.

Genetic regulation of methylation in human endometrium and blood and gene targets for reproductive diseases

Background

Major challenges in understanding the functional consequences of genetic risk factors for human disease are which tissues and cell types are affected and the limited availability of suitable tissue. The aim of this study was to evaluate tissue-specific genotype-epigenetic characteristics in DNA samples from both endometrium and blood collected from women at different stages of the menstrual cycle and relate results to genetic risk factors for reproductive traits and diseases.

Results

We analysed DNA methylation (DNAm) data from endometrium and blood samples from 66 European women. Methylation profiles were compared between stages of the menstrual cycle, and changes in methylation overlaid with changes in transcription and genotypes. We observed large changes in methylation (27,262 DNAm probes) across the menstrual cycle in endometrium that were not observed in blood. Individual genotype data was tested for association with methylation at 443,016 and 443,101 DNAm probes in endometrium and blood respectively to identify methylation quantitative trait loci (mQTLs). A total of 4546 sentinel cis-mQTLs (P < 1.13 × 10⁻¹⁰) and 434 sentinel trans-mQTLs (P < 2.29 × 10⁻¹²) were detected in endometrium and 6615 sentinel cis-mQTLs (P < 1.13 × 10⁻¹⁰) and 590 sentinel trans-mQTLs (P < 2.29 × 10⁻¹²) were detected in blood. Following secondary analyses, conducted to test for overlap between mQTLs in the two tissues, we found that 62% of endometrial cis-mQTLs were also observed in blood and the genetic effects between tissues were highly correlated. A number of mQTL SNPs were associated with reproductive traits and diseases, including one mQTL located in a known risk region for endometriosis (near GREB1).

Conclusions

We report novel findings characterising genetic regulation of methylation in endometrium and the association of endometrial mQTLs with endometriosis risk and other reproductive traits and diseases. The high correlation of genetic effects between tissues highlights the potential to exploit the power of large mQTL datasets in endometrial research and identify target genes for functional studies. However, tissue-specific methylation profiles and genetic effects also highlight the importance of also using disease-relevant tissues when investigating molecular mechanisms of disease risk.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0648-7) contains supplementary material, which is available to authorized users.

The multi-functional roles of menstrual blood-derived stem cells in regenerative medicine

Menstrual blood-derived stem cells (MenSCs) are a novel source of mesenchymal stem cells (MSCs). MenSCs are attracting more and more attention since their discovery in 2007. MenSCs also have no moral dilemma and show some unique features of known adult-derived stem cells, which provide an alternative source for the research and application in regenerative medicine. Currently, people are increasingly interested in their clinical potential due to their high proliferation, remarkable versatility, and periodic acquisition in a non-invasive manner with no other sources of MSCs that are comparable in adult tissue. In this review, the plasticity of pluripotent biological characteristics, immunophenotype and function, differentiative potential, and immunomodulatory properties are assessed. Furthermore, we also summarize their therapeutic effects and functional characteristics in various diseases, including liver disease, diabetes, stroke, Duchenne muscular dystrophy, ovarian-related disease, myocardial infarction, Asherman syndrome, Alzheimer’s disease, acute lung injury, cutaneous wound, endometriosis, and neurodegenerative diseases. Subsequently, the clinical potential of MenSCs is investigated. There is a need for a deeper understanding of its immunomodulatory and diagnostic properties with safety concern on a variety of environmental conditions (such as epidemiological backgrounds, age, hormonal status, and pre-contraceptive). In summary, MenSC has a great potential for reducing mortality and improving the quality of life of severe patients. As a kind of adult stem cells, MenSCs have multiple properties in treating a variety of diseases in regenerative medicine for future clinical applications.

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.

Pathogenesis of endometriosis: the genetic/epigenetic theory

OBJECTIVE

To study the pathophysiology of endometriosis.

DESIGN

Overview of observations on endometriosis.

SETTING

Not applicable.

PATIENT(S)

None.

INTERVENTIONS(S)

None.

MAIN OUTCOME MEASURE(S)

The hypothesis is compatible with all observations.

RESULT(S)

Endometriosis, endometrium-like tissue outside the uterus, has a variable macroscopic appearance and a poorly understood natural history. It is a hereditary and heterogeneous disease with many biochemical changes in the lesions, which are clonal in origin. It is associated with pain, infertility, adenomyosis, and changes in the junctional zone, placentation, immunology, plasma, peritoneal fluid, and chronic inflammation of the peritoneal cavity. The Sampson hypothesis of implanted endometrial cells following retrograde menstruation, angiogenic spread, lymphogenic spread, or the metaplasia theory cannot explain all observations if metaplasia is defined as cells with reversible changes and an abnormal behavior/morphology due to the abnormal environment. We propose a polygenetic/polyepigenetic mechanism. The set of genetic and epigenetic incidents transmitted at birth could explain the hereditary aspects, the predisposition, and the endometriosis-associated changes in the endometrium, immunology, and placentation. To develop typical, cystic ovarian or deep endometriosis lesions, a variable series of additional transmissible genetic and epigenetic incidents are required to occur in a cell which may vary from endometrial to stem cells. Subtle lesions are viewed as endometrium in a different environment until additional incidents occur. Typical cystic ovarian or deep endometriosis lesions are heterogeneous and represent three different diseases.

CONCLUSION(S)

The genetic epigenetic theory is compatible with all observations on endometriosis. Implications for treatment and prevention are discussed.

Human menstrual blood: a renewable and sustainable source of stem cells for regenerative medicine

Stem cells (SCs) play an important role in autologous and even allogenic applications. Menstrual blood discharge has been identified as a valuable source of SCs which are referred to as menstrual blood-derived stem cells (MenSCs). Compared to SCs from bone marrow and adipose tissues, MenSCs come from body discharge and obtaining them is non-invasive to the body, they are easy to collect, and there are no ethical concerns. There is, hence, a growing interest in the functions of MenSCs and their potential applications in regenerative medicine. This review presents recent progress in research into MenSCs and their potential application. Clinical indications of using MenSCs for various regenerative medicine applications are emphasized, and future research is recommended to accelerate clinical applications of MenSCs.

Cytogenetic and Transcriptomic Analysis of Human Endometrial MSC Retaining Proliferative Activity after Sublethal Heat Shock

Temperature is an important exogenous factor capable of leading to irreversible processes in the vital activity of cells. However, the long-term effects of heat shock (HS) on mesenchymal stromal cells (MSC) remain unstudied. We investigated the karyotype and DNA repair drivers and pathways in the human endometrium MSC (eMSC) survived progeny at passage 6 after sublethal heat stress (sublethal heat stress survived progeny (SHS-SP)). G-banding revealed an outbreak of random karyotype instability caused by chromosome breakages and aneuploidy. Molecular karyotyping confirmed the random nature of this instability. Transcriptome analysis found homologous recombination (HR) deficiency that most likely originated from the low thermostability of the AT-rich HR driving genes. SHS-SP protection from transformation is provided presumably by low oncogene expression maintained by tight co-regulation between thermosensitive HR drivers BRCA, ATM, ATR, and RAD51 (decreasing expression after SHS), and oncogenes mTOR, MDM2, KRAS, and EGFR. The cancer-related transcriptomic features previously identified in hTERT transformed MSC in culture were not found in SHS-SP, suggesting no traits of malignancy in them. The entrance of SHS-SP into replicative senescence after 25 passages confirms their mortality and absence of transformation features. Overall, our data indicate that SHS may trigger non-tumorigenic karyotypic instability due to HR deficiency and decrease of oncogene expression in progeny of SHS-survived MSC. These data can be helpful for the development of new therapeutic approaches in personalized medicine.

The Clinical Anatomy of Endometriosis: A Review

Endometriosis is a gynecological disorder identified by the presence of ectopic endometrial tissue outside the uterus. Largely, it affects reproductive-aged women and is a major cause of infertility. Clinical manifestations of endometriosis include dyspareunia, cyclic menstrual pain, chronic pelvic pain, and dyschezia, all of which can affect the patient's quality of life and health severely; therefore, it is paramount that medical treatment is initiated as soon as endometriosis is suspected clinically. In this review, we examine the known anatomic principles of endometriosis in the literature and outline ways to manage patients with this condition better.

Endometrial Stem Cells in Farm Animals: Potential Role in Uterine Physiology and Pathology

The endometrium is an accessible source of mesenchymal stem cells. Most investigations of endometrial mesenchymal stem cells (eMSCs) have been conducted in humans. In animals, particularly in livestock, eMSC research is scarce. Such cells have been described in the bovine, ovine, caprine, porcine, and equine endometrium. Here we provide the state of the art of eMSCs in farm animals with a focus on the bovine species. In bovines, eMSCs have been identified during the phases of the estrous cycle, during which their functionality and the presence of eMSC-specific markers has been shown to change. Moreover, postpartum inflammation related to endometritis affects the presence and functionality of eMSCs, and prostaglandin E₂ (PGE₂) may be the mediator of such changes. We demonstrated that exposure to PGE₂ in vitro modifies the transcriptomic profile of eMSCs, showing its potential role in the fate of stem cell activation, migration, and homing during pathological uterine inflammation in endometritis and in healthy puerperal endometrium. Farm animal research on eMSCs can be of great value in translational research for certain uterine pathologies and for immunomodulation of local responses to pathogens, hormones, and other substances. Further research is necessary in areas such as in vivo location of the niches and their immunomodulatory and anti-infective properties.

Comparison of CD9 & CD146 markers in endometrial stromal cells of fertile & infertile females

Background & objectives

CD9 and CD146 are important adhesion molecules that play a role in the implantation of an embryo. This study was undertaken to correlate the expression of these markers in fertile and infertile women's endometrial stromal cells.

Methods

Human endometrial stromal cell culture from endometrial biopsies of fertile (n=50) and infertile females (n=50) was performed and primary cell lines were established. Expression of CD9 and CD146 was studied for all the 100 cell lines with the help of flow cytometry. Gene expression of CD9 and CD146 was performed by real-time polymerase chain reaction.

Results

There was a significant difference in endometrial stromal cells of fertile and infertile females. Flow cytometric results revealed significantly lower expression of CD9 (P=0.0126) and CD146 (P=0.0006) in the infertile endometrial stromal cells as compared to fertile endometrial stromal cells. These results were comparable with real-time data.

Interpretation & conclusions

This study showed that endometrial stromal cells from infertile females had lower expression of adhesion molecules, CD9 and CD146. Our findings suggest that CD9 and CD146 may have a role in infertility. Infertile female's endometrial stromal cells have decreased expression of CD9 and CD146 which can be the cause of infertility related to implantation failure.

Human menstrual blood-derived stem cells promote functional recovery in a rat spinal cord hemisection model

Spinal cord injury (SCI) is associated with a dismal prognosis including severe voluntary motor and sensory deficits in the presence of the current therapies, thus new and efficient treatment strategies are desperately required. Along with several advantages, such as easy accessibility, high-yield, potential of enormous proliferation, menstrual blood-derived mesenchymal stem cells (MenSCs) have been proposed as a promising strategy in regeneration medicine. In this study, the MenSCs were transplanted into incomplete thoracic (T10) spinal cord injury (SCI) rats, all rats were sacrificed at 7, 14, and 28 days after surgery. Based on the results, we found that MenSCs transplantation improved the hind limb motor function. Besides, H&E staining showed that MenSCs treatment markedly reduced cavity formation in the lesion site. Furthermore, treatment by MenSCs showed more MAP2-positive mature neurons, as well as axonal regeneration manifested by NF-200 and less expression of chondroitin sulfate proteoglycans (CSPGs) than the non-treatment in the lesion site. Additionally, immunofluorescence, Western blot, and qRT-PCR methods showed that levels of brain-derived neurotrophic factor (BDNF) were significantly higher in the injured spinal cord after implantation of MenSCs. Results of qRT-PCR indicated that inflammatory factors, including TNF-α and IL-1β were inhibited after MenSCs transplantation. The improved motor function of hind limb and the increased cell body area of motor neurons were suppressed by blocking of the BDNF-TrkB signaling. It was eventually revealed that MenSCs implantation had beneficial therapeutic effects on the rehabilitation of the rat spinal cord hemisection model, mainly by enhancing the expression of BDNF. MenSCs transplantation may provide a novel therapeutic strategy for patients with SCI in the future.

Evaluation of Vav3.1 as prognostic marker in endometrial cancer

PURPOSE

Vav3 is a guanine nucleotide exchange factor that regulates the activity of Rho/Rac family GTPases. In a study on ovarian cancer, we recently demonstrated pronounced prognostic and predictive value of Vav3.1, a specific truncation variant of the parental Vav3 gene. Here, we sought to investigate the role of Vav3.1 in the most prevalent gynecological tumor entity, endometrial cancer.

METHODS

Vav3.1 transcript levels were determined in a large cohort of endometrial cancer patients using variant-specific PCR (n = 239), and non-malignant endometrial tissue served as control (n = 26). Expression levels of Vav3.1 were stratified according to established clinicopathological characteristics and correlated to long-term patient survival (average follow-up of > 7.5 years). Type 1 and type 2 cancers were separately investigated.

RESULTS

While Vav3.1 was markedly overexpressed in endometrial cancer tissue, we could not detect associations with clinical parameters related to prognosis, such as FIGO stage and tumor grade. Kaplan-Meier estimators of different measures of survival failed to show prognostic significance of Vav3.1 in endometrial cancer. Lack of prognostic value was observed for both type 1 and type 2 cancers.

CONCLUSIONS

Our study shows that Vav3.1 is not suited as a marker of cancer progression and/or treatment response in endometrial cancer. Feasibility and potential benefit of targeting Vav3.1 in endometrial cancer needs to be evaluated in future studies, proceeding from its clear, roughly ten-fold, induction in the malignant endometrium.

Inflammatory cytokine profile of co‑cultivated primary cells from the endometrium of women with and without endometriosis

Endometriosis is a chronic gynecological disorder defined as the presence of endometrial tissue within extra-uterine sites. The primary symptoms are infertility and chronic pain. The inflammatory environment and aberrant immune responses in women with endometriosis may be directly associated with the initiation and progression of endometriotic lesions. In the present study, the secretion of inflammatory cytokines was evaluated in cultures of primary endometrial cells (ECs) isolated from the endometrium of women with and without endometriosis. The presence of endometriotic cells leads to alterations in the secretory profile of healthy ECs. The expression of the inflammatory cytokines interleukin (IL)‑6 and IL‑8 was significantly increased in endometriotic and co‑cultured cells compared with healthy ECs. IL‑6 expression was strongly correlated with IL‑8 expression in endometriotic cells. IL‑1β expression was increased on day 10 of co‑culture to 48.30 pg/ml and may be associated with the long‑term co‑culture, rather than IL‑6 and IL‑8 expression. IL‑6 expression was strongly correlated with cell number, whereas IL‑8 expression was moderately correlated with cell number. Additionally, it was observed that co‑cultured cells exhibited a different population of cells, with expression of the mesenchymal stem cell marker cell surface glycoprotein MUC18, indicating a putative role of endometrial mesenchymal stem cells in the secretion of cytokines and disease development. These results indicate a predominant role of primary endometriotic cells in the secretion of cytokines, which contributes to the disrupted peritoneal and endometrial environment observed in the women with endometriosis.

Endometriosis

Endometriosis is a common inflammatory disease characterized by the presence of tissue outside the uterus that resembles endometrium, mainly on pelvic organs and tissues. It affects ~5-10% of women in their reproductive years - translating to 176 million women worldwide - and is associated with pelvic pain and infertility. Diagnosis is reliably established only through surgical visualization with histological verification, although ovarian endometrioma and deep nodular forms of disease can be detected through ultrasonography and MRI. Retrograde menstruation is regarded as an important origin of the endometrial deposits, but other factors are involved, including a favourable endocrine and metabolic environment, epithelial-mesenchymal transition and altered immunity and inflammatory responses in genetically susceptible women. Current treatments are dictated by the primary indication (infertility or pelvic pain) and are limited to surgery and hormonal treatments and analgesics with many adverse effects that rarely provide long-term relief. Endometriosis substantially affects the quality of life of women and their families and imposes costs on society similar to those of other chronic conditions such as type 2 diabetes mellitus, Crohn's disease and rheumatoid arthritis. Future research must focus on understanding the pathogenesis, identifying disease subtypes, developing non-invasive diagnostic methods and targeting non-hormonal treatments that are acceptable to women who wish to conceive.

Eminent Sources of Adult Mesenchymal Stem Cells and Their Therapeutic Imminence

In the recent times, stem cell biology has garnered the attention of the scientific fraternity and the general public alike due to the immense therapeutic potential that it holds in the field of regenerative medicine. A breakthrough in this direction came with the isolation of stem cells from human embryo and their differentiation into cell types of all three germ layers. However, the isolation of mesenchymal stem cells from adult tissues proved to be advantageous over embryonic stem cells due to the ethical and immunological naivety. Mesenchymal Stem Cells (MSCs) isolated from the bone marrow were found to differentiate into multiple cell lineages with the help of appropriate differentiation factors. Furthermore, other sources of stem cells including adipose tissue, dental pulp, and breast milk have been identified. Newer sources of stem cells have been emerging recently and their clinical applications are also being studied. In this review, we examine the eminent sources of Mesenchymal Stem Cells (MSCs), their immunophenotypes, and therapeutic imminence.

Stromal fibroblasts from perimenopausal endometrium exhibit a different transcriptome than those from the premenopausal endometrium

Human endometrium undergoes extensive regeneration on a cyclic basis in premenopausal women and likely occurs through the contribution of stem/progenitor cells. Menopause results in the permanent cessation of menstrual cycles and is preceded by perimenopause, a period of several years in which endocrine and biological changes occur and is a period of risk for endometrial proliferative disorders. The objectives of this study were to identify endometrial mesenchymal stem cells (eMSC) and endometrial stromal fibroblasts (eSF) in endometrium of perimenopausal women and perform expression profile analysis of perimenopausal eMSC and eSF to gain insight into the biology of stem/progenitor and lineage cell populations during the transition to menopause. Endometrial tissue was collected from perimenopausal and premenopausal women (n = 9 each). Microarray analysis was performed on fluorescence-activated cell sorting-isolated eSF and eMSC, and data were validated by quantitative real-time PCR. Principal component analysis showed that cells clustered into three distinct groups in 3-dimensional space: perimenopausal eMSC and premenopausal eMSC clustered together, while perimenopausal eSF and premenopausal eSF formed two discrete clusters separate from eMSC. Hierarchical clustering revealed a branching pattern consistent with principle clustering analysis results, indicating that eMSC from premenopausal and perimenopausal women exhibit similar transcriptomic signatures. Pathway analysis revealed dysregulation of cytoskeleton, proliferation, and survival pathways in perimenopausal vs. premenopausal eSF. These data demonstrate that cell populations have altered gene expression in perimenopausal vs. premenopausal endometrium, and that perimenopausal eSF had altered pathway activation when compared to premenopausal eSF. This study provides insight into aging endometrium with relevance to function in reproductively older women.

Synchrotron- and focal plane array-based Fourier-transform infrared spectroscopy differentiates the basalis and functionalis epithelial endometrial regions and identifies putative stem cell regions of human endometrial glands

The cyclical process of regeneration of the endometrium suggests that it may contain a cell population that can provide daughter cells with high proliferative potential. These cell lineages are clinically significant as they may represent clonogenic cells that may also be involved in tumourigenesis as well as endometriotic lesion development. To determine whether the putative stem cell location within human uterine tissue can be derived using vibrational spectroscopy techniques, normal endometrial tissue was interrogated by two spectroscopic techniques. Paraffin-embedded uterine tissues containing endometrial glands were sectioned to 10-μm-thick parallel tissue sections and were floated onto BaF₂ slides for synchrotron radiation-based Fourier-transform infrared (SR-FTIR) microspectroscopy and globar focal plane array-based FTIR spectroscopy. Different spectral characteristics were identified depending on the location of the glands examined. The resulting infrared spectra were subjected to multivariate analysis to determine associated biophysical differences along the length of longitudinal and crosscut gland sections. Comparison of the epithelial cellular layer of transverse gland sections revealed alterations indicating the presence of putative transient-amplifying-like cells in the basalis and mitotic cells in the functionalis. SR-FTIR microspectroscopy of the base of the endometrial glands identified the location where putative stem cells may reside at the same time pointing towards ν_sPO₂⁻ in DNA and RNA, nucleic acids and amide I and II vibrations as major discriminating factors. This study supports the view that vibration spectroscopy technologies are a powerful adjunct to our understanding of the stem cell biology of endometrial tissue.

Graphical abstract

A comparison study on the behavior of human endometrial stem cell-derived osteoblast cells on PLGA/HA nanocomposite scaffolds fabricated by electrospinning and freeze-drying methods

Background

An engineered tissue structure is an artificial scaffold combined with cells and signaling factors. Among various polymers, the polylactide-co-glycolide/hydroxyapatite (PLGA/HA) has attracted much attention due to their optimal properties. The aim of this study was to study the behavior of human endometrial stem cell (hEnSC)-derived osteoblast cells cultured on PLGA/HA nanocomposite scaffolds.

Methods

hEnSCs were isolated and exposed to osteogenic media for 21 days. Differentiated cells were cultured on PLGA/HA synthetic scaffolds. The PLGA/HA-based nanocomposite scaffolds were fabricated using either electrospinning or freeze-drying methods. Behavior of the cells was evaluated a week after seeding hEnSC-derived osteoblast-like cells on these scaffolds. Osteogenesis was investigated in terms of alkaline phosphatase activity, gene expression, immunocytochemistry (ICC), proliferation, and scanning electron microscopy (SEM). Moreover, scaffold properties, such as pore size and morphology of the cells, onto the scaffolds were evaluated using SEM. Furthermore, biocompatibility of these scaffolds was confirmed by 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

Results

The matrix mineralization was proved by alizarin red staining, and the osteogenic media-treated cultures positively expressed osteocalcin and osteopontin markers. Moreover, qRT-PCR results confirmed the positive gene expression of osteopontin and osteonectin in the differentiated osteoblast-like cells. The results of behavior assessment of the cultured cells on electrospinning and freeze-dried scaffolds showed that the behavior of the cultured cells on the freeze-dried PLGA/HA scaffolds was significantly better than the electrospinning PLGA/HA scaffolds.

Conclusion

It has been shown that the freeze-dried PLGA/HA nanocomposite scaffolds can appropriately support the attachment and proliferation of the differentiated osteoblast cells and are a suitable candidate for bone tissue engineering.

Stem cell therapy in Asherman syndrome and thin endometrium: Stem cell- based therapy

The endometrium is one of the essential components of the uterus. The endometrium of human is a complex and dynamic tissue, which undergoes periods of growth and turn over during any menstrual cycle. Stem cells are initially undifferentiated cells that display a wide range of differentiation potential with no distinct morphological features. Stem cell therapy method recently has become a novel procedure for treatment of tissue injury and fibrosis in response to damage. Currently, there is massive interest in stem cells as a novel treatment method for regenerative medicine and more specifically for the regeneration of human endometrium disorder like Asherman syndrome (AS) and thin endometrium. AS also known as intrauterine adhesion (IUA) is a uterine disorder with the aberrant creation of adhesions within the uterus and/or cervix. Patients with IUA are significantly associated with menstrual abnormalities and suffer from pelvic pain. In addition, IUA might prevent implantation of the blastocyst, impair the blood supply to the uterus and early fetus, and finally result in the recurrent miscarriage or infertility in the AS patients. It has been evidenced that the transplantation of different stem cells with a diverse source in the endometrial zone had effects on endometrium such as declined the fibrotic area, an elevated number of glands, stimulated angiogenesis, the enhanced thickness of the endometrium, better formed tissue construction, protected gestation, and improved pregnancy rate. This study presents a summary of the investigations that indicate the key role of stem cell therapy in regeneration and renovation of defective parts.

Effects of platelet-rich plasma on the activity of human menstrual blood-derived stromal cells in vitro

Background

Human menstrual blood-derived stromal cells (MenSCs) are highly proliferative and show multiple differentiation capacity. The convenience and non-invasiveness make MenSC a novel cell source for regenerative medicine applications. Platelet-rich plasma (PRP) contains abundant growth factors which are beneficial to wound healing. However, the influence of PRP on MenSCs remains elusive. Here, we evaluated the role of PRP in MenSCs proliferation and assessed the effects of PRP on endometrial receptivity regulation in vitro.

Methods

MenSCs cultured with 10% activated PRP were compared with those cultured with 10% fetal bovine serum (FBS). Differences in cell proliferation, differentiation, and endometrial receptivity-related gene expression were evaluated.

Results

Notably, 10% activated PRP significantly promoted MenSCs proliferation and adipogenic/osteogenic differentiation while suppressing apoptosis. Expression of the mesenchymal stem cells (MSCs) marker CD105 and the perivascular markers SUSD2 and CD146 were elevated after PRP treatment. Moreover, short-term PRP stimulation activated the phosphorylation of Akt and signal transducer and activator of transcription 3 (STAT3) pathways, upregulated expression of FoxO1, LIF, and IL1-β, and downregulated IL-6.

Conclusions

In summary, PRP could promote MenSC proliferation, markedly accelerate cell stemness, and evaluate MenSC functions by enhancing the expression of angiogenesis and endometrial receptivity markers, suggesting its potential use as a promising supplement for MenSCs in endometrial regenerative medicine. Our results provide a theoretical basis for the clinical application of co-transplantation of PRP combined with MenSCs.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0795-3) contains supplementary material, which is available to authorized users.

Pathogenesis of endometriosis: Interaction between Endocrine and inflammatory pathways

Despite an estimated prevalence of 11% in women and plausible historical descriptions dating back to the 17th century, the etiology of endometriosis remains poorly understood. Classical theories of the histological origins of endometriosis are reviewed below. Clinical presentations are variable, and signs and symptoms do not correlate well with the extent of disease. In this summary, we have attempted to synthesize the growing evidence that hormonal and immune factors conspire to activate a local inflammatory microenvironment that encourages endometriosis to persist and elaborate mediators of its two cardinal symptoms: pain and infertility. Surprisingly, in the search for novel therapeutics for medical treatment of endometriosis, some compounds appear to have dual pharmacological functions, simultaneously modifying the endocrine and immune system facets of this complex gynecologic syndrome. We predict that these lead drugs will provide more therapeutic choices for patients in the future.

Endometriosis risk alleles at 1p36.12 act through inverse regulation of CDC42 and LINC00339

Genome-wide association studies (GWAS) have identified markers within the WNT4 region on chromosome 1p36.12 showing consistent and strong association with increasing endometriosis risk. Fine mapping using sequence and imputed genotype data has revealed strong candidates for the causal SNPs within these critical regions; however, the molecular pathogenesis of these SNPs is currently unknown. We used gene expression data collected from whole blood from 862 individuals and endometrial tissue from 136 individuals from independent populations of European descent to examine the mechanism underlying endometriosis susceptibility. Association mapping results from 7,090 individuals (2,594 cases and 4,496 controls) supported rs3820282 as the SNP with the strongest association for endometriosis risk (P = 1.84 × 10−5, OR = 1.244 (1.126-1.375)). SNP rs3820282 is a significant eQTL in whole blood decreasing expression of LINC00339 (also known as HSPC157) and increasing expression of CDC42 (P = 2.0 ×10−54 and 4.5x10−4 respectively). The largest effects were for two LINC00339 probes (P = 2.0 ×10−54; 1.0 × 10−34). The eQTL for LINC00339 was also observed in endometrial tissue (P = 2.4 ×10−8) with the same direction of effect for both whole blood and endometrial tissue. There was no evidence for eQTL effects for WNT4. Chromatin conformation capture provides evidence for risk SNPs interacting with the promoters of both LINC00339 and CDC4 and luciferase reporter assays suggest the risk SNP rs12038474 is located in a transcriptional silencer for CDC42 and the risk allele increases expression of CDC42. However, no effect of rs3820282 was observed in the LINC00339 expression in Ishikawa cells. Taken together, our results suggest that SNPs increasing endometriosis risk in this region act through CDC42, but further functional studies are required to rule out inverse regulation of both LINC00339 and CDC42.

The significance and evolution of menstruation

Historically, the evolutionary origins of menstruation have been based on two theories: the ability to eliminate infectious agents carried to the uterus with spermatozoa and the comparative conservation of energy with menstruation compared to its absence. In the menstruating species, more recent theories have identified spontaneous decidualization as the key adaptive mechanism. Spontaneous decidualization is seen as a mechanism to provide the mother with protection from the invasive characteristics of the embryo. Physiologically, menstruation involves complex interactions of inflammation and vascular mechanisms to stabilize the endometrium and allow a regulated loss of endometrial tissues and blood. A variety of human illnesses can be better understood as vulnerabilities associated with these evolutionary developments, including recurrent pregnancy loss, placenta accreta, ectopic pregnancy, endometriosis, adenomyosis, dysmenorrhea, and chronic pelvic pain. While the evolutionary aspects of these diseases indicate why such illnesses can occur, in some instances, they also provide a basis for treatment, prevention and future research direction.

Endometrial stem/progenitor cells and their role in the pathogenesis of endometriosis

Human endometrium regenerates on a cyclical basis each month, likely mediated by endometrial stem/progenitor cells. Several types of stem/progenitor cells have been identified: CD140b⁺CD146⁺ or SUSD2⁺ endometrial mesenchymal stem cells (eMSCs), N-cadherin⁺ endometrial epithelial progenitor cells (eEPs), and side population (SP) cells, a heterogeneous population predominantly comprising endothelial cells. eMSCs reside in a perivascular niche and likely mediate angiogenesis and stromal regeneration. Human eEPs are located in the bases of glands in the basalis and are likely more primitive than SSEA-1⁺ basalis epithelial cells. Endometrial stem/progenitor cells may contribute to the pathogenesis of endometriosis by their retrograde shedding into the pelvic cavity, either after menarche or as a result of neonatal uterine bleeding. eMSCs may have a role in the generation of progesterone-resistant phenotype of endometrial stromal fibroblasts (eSFs) in endometriosis. In future clinical practice, endometrial stem/progenitor cells may be used to establish diagnosis of endometriosis or as therapeutic targets.

In vitro evidence that platelet-rich plasma stimulates cellular processes involved in endometrial regeneration

PURPOSE

The study aims to test the hypothesis that platelet-rich plasma (PRP) stimulates cellular processes involved in endometrial regeneration relevant to clinical management of poor endometrial growth or intrauterine scarring.

METHODS

Human endometrial stromal fibroblasts (eSF), endometrial mesenchymal stem cells (eMSC), bone marrow-derived mesenchymal stem cells (BM-MSC), and Ishikawa endometrial adenocarcinoma cells (IC) were cultured with/without 5% activated (a) PRP, non-activated (na) PRP, aPPP (platelet-poor-plasma), and naPPP. Treatment effects were evaluated with cell proliferation (WST-1), wound healing, and chemotaxis Transwell migration assays. Mesenchymal-to-epithelial transition (MET) was evaluated by cytokeratin and vimentin expression. Differential gene expression of various markers was analyzed by multiplex Q-PCR.

RESULTS

Activated PRP enhanced migration of all cell types, compared to naPRP, aPPP, naPPP, and vehicle controls, in a time-dependent manner (p < 0.05). The WST-1 assay showed increased stromal and mesenchymal cell proliferation by aPRP vs. naPRP, aPPP, and naPPP (p < 0.05), while IC proliferation was enhanced by aPRP and aPPP (p < 0.05). There was no evidence of MET. Expressions of MMP1, MMP3, MMP7, and MMP26 were increased by aPRP (p < 0.05) in eMSC and eSF. Transcripts for inflammation markers/chemokines were upregulated by aPRP vs. aPPP (p < 0.05) in eMSC and eSF. No difference in estrogen or progesterone receptor mRNAs was observed.

CONCLUSIONS

This is the first study evaluating the effect of PRP on different human endometrial cells involved in tissue regeneration. These data provide an initial ex vivo proof of principle for autologous PRP to promote endometrial regeneration in clinical situations with compromised endometrial growth and scarring.

Does migrative and proliferative capability of epithelial cells reflect cellular developmental competence?

Mammalian epithelial and epithelial-like cells are significantly involved in various processes associated with tissue development, differentiation and oncogenesis. Because of that, high number of research is focused on identifying cells that express stem-like or progenitor characteristics. Identifying such cells and recognizing their specific markers, would open new clinical opportunities in transplantology and oncology. There are several epithelia characterized by their ability to rapidly proliferate and/or differentiate. Due to their function or location they are subject to cyclic changes involving processes of apoptosis and regeneration. Literature presenting well-structured studies of these types of epithelia was analyzed in order to compare various results and establish if epithelial cells’ migrative and proliferative ability indicates their stemness potential. Endometrial, ovarian, oviductal and oral mucosal epithelia were analyzed with most of the publications delivering relatively unified results. The ability to rapidly proliferate/differentiate usually indicated the presence of some kind of stem/stem-like/progenitor cells. Most of the papers focused on pinpointing the exact location of these kind of cells, or analyzing specific markers that would be used for their future identification. There have also been substantial proportion of research that focused on discovering growth factors or intercellular signals that induced proliferation/differentiation in analyzed epithelia. Most of the research provided valuable insights into the modes of function and characteristics of the analyzed tissue, outlining the importance of such study for the possible clinical application of in vitro derived cell cultures.

Mesenchymal Stem Cell Therapy Prevents Abortion in CBA/J × DBA/2 Mating

Immunological disorders are among the main causes of recurrent spontaneous abortions (RSAs). Mesenchymal stem cells (MSCs) have been shown to modulate various aspects of immune responses. It seems that MSCs may improve the immunological conditions in immune-mediated RSA. The aim of this study is the reduction of resorption in RSA mouse model through MSCs therapy. The adipose-derived MSCs were administered intraperitoneal to pregnant CBA/J mice on day 4.5 of gestation in abortion-prone matting. On day 13.5 of pregnancy, abortion rates were calculated and transforming growth factor-β (TGF-β), interleukin 10 (IL-10), interferon γ (IFN-γ), and tumor necrosis factor α (TNF-α) gene expression in deciduas were evaluated by real-time polymerase chain reaction (PCR). The level of TGF-β in serum was also determined by enzyme linked immunosorbent assay (ELISA) method. The obtained results showed that MSCs therapy could reduce the abortion rate significantly in test group compared to controls. MSCs therapy also caused a significant upregulation of TGF-β and IL-10 and downregulation of IFN-γ and TNF-α genes expression in deciduas. However, the levels of TGF-β didn't change in mice sera. Due to the significant decrease in abortion rate, we concluded that MSCs therapy could modulate the immune responses in fetomaternal interface and protect fetus from undesirable immune responses. So, these cells might be considered as a new therapeutic for spontaneous pregnancy loss. The local upregulation of TGF-β and IL-10 and downregulation of IFN-γ and TNF-α gene expression in decidua could be considered as one possible mechanism of immune regulation, which could protect the fetus.

Curcumin and endometriosis: Review on potential roles and molecular mechanisms

Endometriosis, an estrogen-dependent inflammatory disease, is one of the most common chronic gynecological disorders affecting women in reproductive age. It is characterized by the presence of endometrial-like tissue outside the uterus. The exact pathophysiology of endometriosis is not still well-known, but the immune system and inflammation have been considered as pivotal factors in disease progression. Turmeric, an important spice all around the world, is obtained from the rhizomes of Curcuma longa, a member of the Zingiberaceae family. It has been used in the prevention and treatment of many diseases since ancient times. Curcumin is the principal polyphenol isolated from turmeric. Several evidences have shown the anti-inflammatory, antioxidant, anti-tumor, anti-angiogenesis, and anti-metastatic activities of curcumin. In this review, relevant articles on the effect of curcumin on endometriosis and possible molecular mechanisms are discussed.

Differentially expressed genes: OCT-4, SOX2, STAT3, CDH1 and CDH2, in cultured mesenchymal stem cells challenged with serum of women with endometriosis

Endometriosis is a common chronic gynecological disorder defined as the presence of ectopic functional endometrial tissues, outside uterine cavity, primarily on the pelvic peritoneum and the ovaries. Several studies revealed a correlation between aberrant stem-cell activity in the endometrium and endometriosis. Yet the molecular and cellular behaviors of mesnchymal stem cells in development of endometriosis are hampered by lack of invitro experiments. Our aim was to explore morphological and molecular changes associated with mesenchymal stem cells (MSCs) exposition to serum derived from women with severe endometriosis. Two cell cultures of MSCs isolated from endometrial tissues of two endometriosis-free women. Each cell culture was treated individually with the serum of women with endometriosis (experimental group/n = 7), and serum of women without endometriosis (control group/ n = 4) for 14 days. Quantitative Real-Time PCR was performed later to reveal expression of OCT-4, CDH1 and CDH2, STAT3 and SOX2 genes. Morphologically, cells showed no significant changes. However from molecular point of view, we found increased expression in OCT-4, CDH1 and CDH2. For STAT3 and SOX2 we did not find a significant difference. This study shows that endometriosis serum induced molecular changes in human endometrial MSCs (EnMSCs) that might be related to altered cell behavior which may be a step in differentiation that may be completed invivo by other factors to complete the process of transition. Further researches are needed for optimization to reach differentiation.

Regeneration of the Fallopian Tube Mucosa Using Bone Marrow Mesenchymal Stem Cell Transplantation After Induced Chemical Injury in a Rat Model

In this study, we describe a novel insight about the use of bone marrow-derived mesenchymal stem cells (BM-MSCs) for fallopian tube (FT) regeneration. Seventy rats' tubes were involved in this study and divided into 4 groups: control (15), ethanol injured (20), mesenchymal stem cell (MSC)-recipient without injury (15), and MSC recipient after injury (20). The BM-MSCs were isolated from male rats, and their incorporation into the tissues was confirmed by the detection of Sry gene in MSC-recipient rats using RT-PCR. Histological and immunohistological sections of the 4 groups were comparably evaluated. We found that direct injection of ethanol into FT caused structural impairment, which was restored largely after receiving MSCs. We have revealed for the first time that prominin 1 (Prom1, stem cell marker) was expressed in the fimbriated distal tubal end. The MSC transplantation caused (1) significant increase in the tissue level and immunoexpresstion of Prom1 ( P < .001 and P = .017, respectively) and vascular endothelial growth factor (VEGF; vasculogenic marker; P < .001 and P = .004, respectively), (2) significant increase in the immunoexpresstion of proliferating cell nuclear antigen (PCNA; proliferation marker; P < .001), and (3) significant decrease in the immunoexpresstion of caspase 3 (CASP-3; apoptotic marker; P < .001) compared to the injured tissues. In conclusion, MSCs could exhibit its restorative effect on FT through their ability to (1) activate the resident stem cells in the distal tubal end, (2) mediate the expression of VEGF and PCNA, and (3) influence tissue apoptosis. This study laid the foundation for assessing the contribution of stem cells in the distal tubal end in direct repair of the tube when required to assist reproduction.

IL-4-secreting eosinophils promote endometrial stromal cell proliferation and prevent Chlamydia-induced upper genital tract damage

Genital Chlamydia trachomatis infections in women typically are asymptomatic and do not cause permanent upper genital tract (UGT) damage. Consistent with this presentation, type 2 innate and T_H2 adaptive immune responses associated with dampened inflammation and tissue repair are elicited in the UGT of Chlamydia-infected women. Primary C. trachomatis infection of mice also causes no genital pathology, but unlike women, does not generate Chlamydia-specific T_H2 immunity. Herein, we explored the significance of type 2 innate immunity for restricting UGT tissue damage in Chlamydia-infected mice, and in initial studies intravaginally infected wild-type, IL-10^-/-, IL-4^-/-, and IL-4Rα^-/- mice with low-dose C. trachomatis inoculums. Whereas Chlamydia was comparably cleared in all groups, IL-4^-/- and IL-4Rα^-/- mice displayed endometrial damage not seen in wild-type or IL-10^-/- mice. Congruent with the aberrant tissue repair in mice with deficient IL-4 signaling, we found that IL-4Rα and STAT6 signaling mediated IL-4-induced endometrial stromal cell (ESC) proliferation ex vivo, and that genital administration of an IL-4-expressing adenoviral vector greatly increased in vivo ESC proliferation. Studies with IL-4-IRES-eGFP (4get) reporter mice showed eosinophils were the main IL-4-producing endometrial leukocyte (constitutively and during Chlamydia infection), whereas studies with eosinophil-deficient mice identified this innate immune cell as essential for endometrial repair during Chlamydia infection. Together, our studies reveal IL-4-producing eosinophils stimulate ESC proliferation and prevent Chlamydia-induced endometrial damage. Based on these results, it seems possible that the robust type 2 immunity elicited by Chlamydia infection of human genital tissue may analogously promote repair processes that reduce phenotypic disease expression.

ZEB1 expression is a potential indicator of invasive endometriosis

INTRODUCTION

Although endometriosis is a benign disease, it shares some features with cancers, such as invasiveness and the potential to metastasize. This study sought to investigate the epithelial-mesenchymal transition status in human endometriotic lesions.

MATERIAL AND METHODS

Thirteen endometriosis patients and 10 control women without endometriosis undergoing surgery for benign indications were recruited. We examined the expression of E-cadherin, vimentin, and epithelial-mesenchymal transition-induced transcriptional factors, such as Snail and ZEB1, by immunohistochemistry. We evaluated the expression of each marker in epithelial cells of both endometriotic lesions (ovarian endometrioma, deep infiltrating endometriosis, adenomyosis) and normal endometria. The correlation between ZEB1 expression and serum level of CA125 was also investigated.

RESULTS

Immunohistochemical analysis revealed that although E-cadherin, vimentin, and Snail were expressed in epithelia of normal endometria and endometriotic lesions, ZEB1 expression was only expressed in epithelia of endometriotic lesions. Additionally, ZEB1 was most frequently observed in epithelial cells of invasive endometriosis. The endometriosis patients with high serum CA125 level were more likely to have ZEB1-positive lesions.

CONCLUSIONS

This is the first observation of ZEB1 expression in epithelial cells of benign disease. The preferential expression of ZEB1 in epithelial cells of endometriotic lesions suggests that these cells may have, at least in part, a higher level of mesenchymal features possibly via ZEB1-driven epithelial-mesenchymal transition than normal endometria and that ZEB1 can be a potential indicator of invasiveness or severity of endometriosis.

Effects of hypoxia on differentiation of menstrual blood stromal stem cells towards tenogenic cells in a co-culture system with Achilles tendon cells

Achilles tendons have a very poor capacity for intrinsic regeneration. The cell-based treatment strategy for Achilles tendinitis includes the application of mesenchymal stem cells (MSCs), which have high proliferative and multipotent differentiation ability, and is a promising approach. The aim of the present study was to explore the tenogenic potential of human menstrual blood stromal stem cells (MenSCs) in a co-culture system and to compare the tenogenic capability under normoxic and hypoxic conditions. MenSCs were co-cultured indirectly with Achilles tendon cells in a Transwell co-culture system for 1, 2, or 3 weeks in two different concentrations of oxygen (20 and 2% O₂), whereas the control contained only MenSCs. The extracellular matrix of MenSCs in each system was evaluated by Alcian blue staining assay, histological staining, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and western blot analysis. Alcian blue staining assay revealed a significant increase (P<0.05) in proteoglycan secretion by the differentiated MenSCs. Identical results were obtained by RT-qPCR for collagen I, which was validated by western blot analysis. Considerably increased collagen I and collagen III gene expression levels were exhibited by cells in the co-culture treatment group when compared with the control (P<0.05); however, no significant difference was detected between the normoxic (20% O₂) and hypoxic treatment (2% O₂) groups. RT-qPCR was utilized to determine the expression levels of thrombospondin 4, scleraxis and tenascin C in the differentiated MenSCs; a significant increase in the expression of these specific genes was indicated in the co-culture treatment group compared with the control (P<0.05). Although the expression levels were markedly higher in hypoxia than in normoxia conditions, this difference was not significant. To conclude, the present study indicated that MenSCs manifested a strong proliferative and multipotent capacity for differentiation and differentiated into Achilles tenogenic cells. Therefore, the use of MenSCs may be considered in Achilles tendinitis therapy.

Development of organoids from mouse and human endometrium showing endometrial epithelium physiology and long-term expandability

The endometrium, which is of crucial importance for reproduction, undergoes dynamic cyclic tissue remodeling. Knowledge of its molecular and cellular regulation is poor, primarily owing to a lack of study models. Here, we have established a novel and promising organoid model from both mouse and human endometrium. Dissociated endometrial tissue, embedded in Matrigel under WNT-activating conditions, swiftly formed organoid structures that showed long-term expansion capacity, and reproduced the molecular and histological phenotype of the tissue's epithelium. The supplemented WNT level determined the type of mouse endometrial organoids obtained: high WNT yielded cystic organoids displaying a more differentiated phenotype than the dense organoids obtained in low WNT. The organoids phenocopied physiological responses of endometrial epithelium to hormones, including increased cell proliferation under estrogen and maturation upon progesterone. Moreover, the human endometrial organoids replicated the menstrual cycle under hormonal treatment at both the morpho-histological and molecular levels. Together, we established an organoid culture system for endometrium, reproducing tissue epithelium physiology and allowing long-term expansion. This novel model provides a powerful tool for studying mechanisms underlying the biology as well as the pathology of this key reproductive organ.