The human periconceptional maternal-embryonic space in health and disease.

Pregnancy is established during the periconceptional period as a continuum beginning with blastocyst attachment to the endometrial epithelial surface followed by embryo invasion and placenta formation. This period sets the foundation for the child and mother's health during pregnancy. Emerging evidence indicates that prevention of downstream pathologies in both the embryo/newborn and pregnant mother may be possible at this stage. In this review, we discuss current advances in the periconceptional space, including the preimplantation human embryo and maternal endometrium. We also discuss the role of the maternal decidua, the periconceptional maternal-embryonic interface, the dialogue between these elements, and the importance of the endometrial microbiome in the implantation process and pregnancy. Finally, we discuss the myometrium in the periconceptional space and review its role in determining pregnancy health.

A 5-year multicentre randomized controlled trial comparing personalized, frozen and fresh blastocyst transfer in IVF.

RESEARCH QUESTION: Does clinical performance of personalized embryo transfer (PET) guided by endometrial receptivity analysis (ERA) differ from frozen embryo transfer (FET) or fresh embryo transfer in infertile patients undergoing IVF? DESIGN: Multicentre, open-label randomized controlled trial; 458 patients aged 37 years or younger undergoing IVF with blastocyst transfer at first appointment were randomized to PET guided by ERA, FET or fresh embryo transfer in 16 reproductive clinics. RESULTS: Clinical outcomes by intention-to-treat analysis were comparable, but cumulative pregnancy rate was significantly higher in the PET (93.6%) compared with FET (79.7%) (P = 0.0005) and fresh embryo transfer groups (80.7%) (P = 0.0013). Analysis per protocol demonstrates that live birth rates at first embryo transfer were 56.2% in PET versus 42.4% in FET (P = 0.09), and 45.7% in fresh embryo transfer groups (P = 0.17). Cumulative live birth rates after 12 months were 71.2% in PET versus 55.4% in FET (P = 0.04), and 48.9% in fresh embryo transfer (P = 0.003). Pregnancy rates at the first embryo transfer in PET, FET and fresh embryo transfer arms were 72.5% versus 54.3% (P = 0.01) and 58.5% (P = 0.05), respectively. Implantation rates at first embryo transfer were 57.3% versus 43.2% (P = 0.03), and 38.6% (P = 0.004), respectively. Obstetrical outcomes, type of delivery and neonatal outcomes were similar in all groups. CONCLUSIONS: Despite 50% of patients dropping out compared with 30% initially planned, per protocol analysis demonstrates statistically significant improvement in pregnancy, implantation and cumulative live birth rates in PET compared with FET and fresh embryo transfer arms, indicating the potential utility of PET guided by the ERA test at the first appointment.

Cellular therapies for the endometrium: An update.

An update on the current state of endometrial cell therapies in terms of cell types, mechanisms of action, delivery, safety, regulatory frameworks and future perspectives. This review focuses on clinical trials using angiogenesis-promoting therapies and stromal therapies piloted in the last 10 years for alleviating Asherman's syndrome and long-term infertility. All studies present promising preliminary results, indicating increased endometrial thickness and resumed menstruation. Further characterization of individual cell products, their mode of action and larger clinical trials will be essential to establishing cell therapy as a viable option for the treatment of infertility and fertility preservation.

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.

Endometrial Stromal Cells Circulate in the Bloodstream of Women with Endometriosis: A Pilot Study.

Endometriosis is characterized by the presence of endometrial tissue outside the uterus. While endometriotic tissue is commonly localized in the pelvic cavity, it can also be found in distant sites, including the brain. The origin and pathophysiology of tissue migration is poorly understood; retrograde menstruation is thought to be the cause, although the presence of endometrium at distant sites is not explained by this hypothesis. To determine whether dissemination occurs via the bloodstream in women with endometriosis, we analyzed circulating blood for the presence of endometrial cells. Circulating endometrial stromal cells were identified only in women with endometriosis but not in controls, while endometrial epithelial cells were not identified in the circulation of either group. Our results support the hypothesis that endometrial stromal cells may migrate through circulation and promote the pathophysiology of endometriosis. The detection of these cells in circulation creates avenues for the development of less invasive diagnostic tools for the disease, and opens possibilities for further study of the origin of endometriosis.

Lgr5 Does Not Vary Throughout the Menstrual Cycle in Endometriotic Human Eutopic Endometrium.

Endometriosis is characterized by the abnormal presence of endometrium outside of the uterus, resulting in pelvic pain and infertility. The leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) has been postulated to be a marker of stem cells in the endometrium. However, LGR5⁺ cells have a macrophage-like phenotype in this tissue, so it is unclear what role LGR5⁺ cells actually play in the endometrium. Macrophages serve an important function in the endometrium to maintain fertility, while LGR5⁺ cells generally have a role in tumor progression and are involved in invasion in some cancers. We sought to determine whether LGR5⁺ cells vary across the menstrual cycle in women with endometriosis and whether there are implications for LGR5 in the aggressiveness of endometriosis and reproductive outcomes. We performed immunofluorescence, flow cytometry, and primary culture in vitro experiments on eutopic and ectopic endometrium from healthy and endometriosis patients and observed that neither LGR5⁺ cells nor LGR5 expression varied throughout the cycle. Interestingly, we observed that LGR5⁺ cell percentage overexpressing CD163 (anti-inflammatory marker) was higher in healthy endometrium, suggesting that in endometriosis, endometrium presents a more pro-inflammatory phenotype that likely leads to poor obstetric outcomes. We also observed higher levels of LGR5⁺ cells in ectopic lesions compared to eutopic endometrium and specifically in deep infiltrating endometriosis, indicating that LGR5 could be involved in progression and aggressiveness of the disease.

Autologous cell therapy with CD133+ bone marrow-derived stem cells for refractory Asherman's syndrome and endometrial atrophy: a pilot cohort study.

STUDY QUESTION: Could cell therapy using autologous peripheral blood CD133+ bone marrow-derived stem cells (BMDSCs) offer a safe and efficient therapeutic approach for patients with refractory Asherman's syndrome (AS) and/or endometrial atrophy (EA) and a wish to conceive? SUMMARY ANSWER: In the first 3 months, autologous cell therapy, using CD133+ BMDSCs in conjunction with hormonal replacement therapy, increased the volume and duration of menses as well as the thickness and angiogenesis processes of the endometrium while decreasing intrauterine adhesion scores. WHAT IS KNOWN ALREADY: AS is characterized by the presence of intrauterine adhesions and EA prevents the endometrium from growing thicker than 5 mm, resulting in menstruation disorders and infertility. Many therapies have been attempted for these conditions, but none have proved effective. STUDY DESIGN, SIZE, DURATION: This was a prospective, experimental, non-controlled study. There were 18 patients aged 30-45 years with refractory AS or EA were recruited, and 16 of these completed the study. Medical history, physical examination, endometrial thickness, intrauterine adhesion score and neoangiogenesis were assessed before and 3 and 6 months after cell therapy. PARTICIPANTS/MATERIALS, SETTING, METHODS: After the initial hysteroscopic diagnosis, BMDSC mobilization was performed by granulocyte-CSF injection, then CD133+ cells were isolated through peripheral blood aphaeresis to obtain a mean of 124.39 million cells (range 42-236), which were immediately delivered into the spiral arterioles by catheterization. Subsequently, endometrial treatment after stem cell therapy was assessed in terms of restoration of menses, endometrial thickness (by vaginal ultrasound), adhesion score (by hysteroscopy), neoangiogenesis and ongoing pregnancy rate. The study was conducted at Hospital Clínico Universitario of Valencia and IVI Valencia (Spain). MAIN RESULTS AND THE ROLE OF CHANCE: All 11 AS patients exhibited an improved uterine cavity 2 months after stem cell therapy. Endometrial thickness increased from an average of 4.3 mm (range 2.7-5) to 6.7 mm (range 3.1-12) ( ITALIC! P = 0.004). Similarly, four of the five EA patients experienced an improved endometrial cavity, and endometrial thickness increased from 4.2 mm (range 2.7-5) to 5.7 mm (range 5-12) ( ITALIC! P = 0.03). The beneficial effects of the cell therapy increased the mature vessel density and the duration and intensity of menses in the first 3 months, with a return to the initial levels 6 months after the treatment. Three patients became pregnant spontaneously, resulting in one baby boy born, one ongoing pregnancy and a miscarriage. Furthermore, seven pregnancies were obtained after fourteen embryo transfers, resulting in three biochemical pregnancies, one miscarriage, one ectopic pregnancy, one baby born and one ongoing pregnancy. LIMITATIONS, REASONS FOR CAUTION: Limitations of this pilot study include the small sample size and the lack of control group. WIDER IMPLICATIONS OF THE FINDINGS: This novel autologous cell therapy is a promising therapeutic option for patients with these incurable pathologies and a wish to conceive. STUDY FUNDING/COMPETING INTERESTS: This study was funded by the Spanish Ministry of Science and Innovation (SAF 2012-31017, Principal Investigator C.S.), Spanish Ministry of Health (EC11-299, Principal Investigator C.S.) and Regional Valencian Ministry of Education (PROMETEOII/2013/018, Principal Investigator C.S.). Four authors (X.S., I.C., A.P. and C.S.) are co-inventors of the patent resulting from this work (Application number: 62/013,121). S.C., C.A., F.R., J.F., J.P. and J.R. have no conflict of interest in relation to this work. TRIAL REGISTRATION NUMBER: This study was registered with ClinicalTrials.gov (NCT02144987).

Endometrial 'scratching': what the data show.

PURPOSE OF REVIEW: Since its first description in 2003, the endometrial scratching procedure has been the topic of over 1000 studies. This procedure, used to improve endometrial receptivity for assisted reproduction, is accessible - any gynecologist can easily perform it - and has been adapted into clinical routine by some reproductive units. However, the available data are controversial, and no biological plausibility exists to support the use of this intervention. This study aims to critically review the existing data, focusing on the last 2 years, regarding the efficiency of endometrial scratching. RECENT FINDINGS: A total of five randomized controlled studies, one meta-analysis, and a systematic review related to endometrial scratching/injury were published in 2014 and 2015. Considerable heterogeneity exists among these studies regarding the selected population, type of treatment, and even timing and devices used to perform the endometrial injury. Importantly, none of these studies reported improved reproductive outcomes in terms of live birth rates following endometrial scratching. SUMMARY: Overall, data from properly designed and powered randomized controlled studies demonstrate no beneficial effect of this intervention that is based on unknown biological effects. Endometrial scratching produces pain, costs money, and the side-effects of systematic scratching in the production of Asherman syndrome remain to be seen. Think before scratching.

Normothermic Machine Perfusion Systems: Where Do We Go From Here?

Normothermic machine perfusion (NMP) aims to preserve organs ex vivo by simulating physiological conditions such as body temperature. Recent advancements in NMP system design have prompted the development of clinically effective devices for liver, heart, lung, and kidney transplantation that preserve organs for several hours/up to 1 d. In preclinical studies, adjustments to circuit structure, perfusate composition, and automatic supervision have extended perfusion times up to 1 wk of preservation. Emerging NMP platforms for ex vivo preservation of the pancreas, intestine, uterus, ovary, and vascularized composite allografts represent exciting prospects. Thus, NMP may become a valuable tool in transplantation and provide significant advantages to biomedical research. This review recaps recent NMP research, including discussions of devices in clinical trials, innovative preclinical systems for extended preservation, and platforms developed for other organs. We will also discuss NMP strategies using a global approach while focusing on technical specifications and preservation times.

Decoding the endometrial niche of Asherman's Syndrome at single-cell resolution.

Asherman's Syndrome is characterized by intrauterine adhesions or scarring, which cause infertility, menstrual abnormalities, and recurrent pregnancy loss. The pathophysiology of this syndrome remains unknown, with treatment restricted to recurrent surgical removal of intrauterine scarring, which has limited success. Here, we decode the Asherman's Syndrome endometrial cell niche by analyzing data from over 200,000 cells with single-cell RNA-sequencing in patients with this condition and through in vitro analyses of Asherman's Syndrome patient-derived endometrial organoids. Our endometrial atlas highlights the loss of the endometrial epithelium, alterations to epithelial differentiation signaling pathways such as Wnt and Notch, and the appearance of characteristic epithelium expressing secretory leukocyte protease inhibitor during the window of implantation. We describe syndrome-associated alterations in cell-to-cell communication and gene expression profiles that support a dysfunctional pro-fibrotic, pro-inflammatory, and anti-angiogenic environment.

Global endometrial DNA methylation analysis reveals insights into mQTL regulation and associated endometriosis disease risk and endometrial function.

Endometriosis is a leading cause of pain and infertility affecting millions of women globally. Herein, we characterize variation in DNA methylation (DNAm) and its association with menstrual cycle phase, endometriosis, and genetic variants through analysis of genotype data and methylation in endometrial samples from 984 deeply-phenotyped participants. We estimate that 15.4% of the variation in endometriosis is captured by DNAm and identify significant differences in DNAm profiles associated with stage III/IV endometriosis, endometriosis sub-phenotypes and menstrual cycle phase, including opening of the window for embryo implantation. Menstrual cycle phase was a major source of DNAm variation suggesting cellular and hormonally-driven changes across the cycle can regulate genes and pathways responsible for endometrial physiology and function. DNAm quantitative trait locus (mQTL) analysis identified 118,185 independent cis-mQTLs including 51 associated with risk of endometriosis, highlighting candidate genes contributing to disease risk. Our work provides functional evidence for epigenetic targets contributing to endometriosis risk and pathogenesis. Data generated serve as a valuable resource for understanding tissue-specific effects of methylation on endometrial biology in health and disease.

Derivation of insulin producing cells from human endometrial stromal stem cells and use in the treatment of murine diabetes.

Pancreatic islet cell transplantation is an effective approach to treat type 1 diabetes, however the shortage of cadaveric donors and limitations due to rejection require alternative solutions. Multipotent cells derived from the uterine endometrium have the ability to differentiate into mesodermal and ectodermal cellular lineages, suggesting the existence of mesenchymal stem cells in this tissue. We differentiated human endometrial stromal stem cells (ESSC) into insulin secreting cells using a simple and nontransfection protocol. An in vitro protocol was developed and evaluated by assessing the expression of pan ß-cell markers, followed by confirmation of insulin secretion. PAX4, PDX1, GLUT2, and insulin, were all increased in differentiated cells compared to controls. Differentiated cells secreted insulin in a glucose responsive manner. In a murine model, differentiated cells were injected into the kidney capsules of diabetic mice and human insulin identified in serum. Within 5 weeks blood glucose levels were stabilized in animals transplanted with differentiated cells, however those treated with undifferentiated cells developed progressive hyperglycemia. Mice transplanted with control cells lost weight and developed cataracts while those receiving insulin producing cells did not. Endometrium provides an easily accessible, renewable, and immunologically identical source of stem cells with potential therapeutic applications in diabetes.

Individual participant data meta-analysis of trials comparing frozen versus fresh embryo transfer strategy (INFORM): a protocol.

INTRODUCTION: Existing randomised controlled trials (RCTs) comparing a freeze-all embryo transfer strategy and a fresh embryo transfer strategy have shown conflicting results. A freeze-all or a fresh transfer policy may be preferable for some couples undergoing in-vitro fertilisation (IVF), but it is unclear which couples would benefit most from each policy, how and under which protocols. Therefore, we plan a systematic review and individual participant data meta-analysis of RCTs comparing a freeze-all and a fresh transfer policy. METHODS AND ANALYSIS: We will search electronic databases (Medline, Embase, PsycINFO and CENTRAL) and trial registries (ClinicalTrials.gov and the International Clinical Trials Registry Platform) from their inception to present to identify eligible RCTs. We will also check reference lists of relevant papers. The search was performed on 23 September 2020 and will be updated. We will include RCTs comparing a freeze-all embryo transfer strategy and a fresh embryo transfer strategy in couples undergoing IVF. The primary outcome will be live birth resulting from the first embryo transfer. All outcomes listed in the core outcome set for infertility research will be reported. We will invite the lead investigators of eligible trials to join the Individual participant data meta-analysis of trials comparing frozen versus fresh embryo transfer strategy (INFORM) collaboration and share the deidentified individual participant data (IPD) of their trials. We will harmonise the IPD and perform a two-stage meta-analysis and examine treatment-covariate interactions for important baseline characteristics. ETHICS AND DISSEMINATION: The study ethics have been granted by the Monash University Human Research Ethics Committee (Project ID: 30391). The findings will be disseminated via presentations at international conferences and publication in peer-reviewed journals. PROSPERO REGISTRATION NUMBER: CRD42021296566.

Stem cells in human endometrium and endometrial carcinoma.

This study reviews the current knowledge about endometrial somatic stem cells and endometrial cancer stem cells. It describes the main features of somatic stem cells, such as high proliferative potential, self renewal, differentiation into 1 or more lineages, retention of a DNA synthesis label (BrdU), and some methods to identify them (Hoechst dye exclusion test, immunophenotyping). The most likely markers for endometrial somatic stem cells (Oct-4, Musashi-1, CD31, CD34, and CD144) are also mentioned. The study also reviews the literature regarding endometrial cancer stem cells. Results obtained by evaluations of the side population in endometrial cancer cell lines and studies on putative cancer stem cell markers are also discussed. The possible roles of endometrial cancer stem cells in metastasis and resistance to anticancer treatment are also mentioned.

Endometrial Factor in Unexplained Infertility and Recurrent Implantation Failure.

Unexplained infertility (UI) and recurrent implantation failure (RIF) are diagnoses based on failed pregnancy attempts within current infertility treatment models. Both diagnoses are made when fertility is unexplained based on current diagnostic methods and has no clear cause; UI is diagnosed when testing is inconclusive, and RIF is diagnosed after three failed in vitro fertilization cycles. In both cases, interventions are often introduced without an understanding of the cause of the infertility, frequently leading to frustration for patients and caregivers. Here, we review evidence to support an influence of endometrial factor in patients given these poorly defined diagnoses and possible treatments targeting the endometrium to improve outcomes in these patients.

HPV determination in the control after LEEP due to CIN II-III: prospective study and predictive model.

To evaluate the usefulness of the endocervical cytology immediately after loop electrosurgical excision procedure (LEEP) and viral human papilloma virus (HPV) determination as predictive factors of persistence/recurrence (P/R) of squamous intraepithelial lesion (SIL) in the remaining cervix of patients treated with LEEP due to cervical intraepithelial neoplasia (CIN) II or III. We retrospectively selected 105 samples from 100 patients with histologic diagnosis of CIN II-III with cytology immediately after LEEP with a first control post-LEEP between 2 and 6 months after treatment that included HPV determination, a minimal follow-up period of 12 months and maximum of 24 months, and at least 2 colpocytologic controls post-LEEP. In 71 of the 105 patients (67.6%), the determination was negative, finding the presence of HPV in 34 patients (32.4 %). Almost two-thirds of the patients had negative endocervical cytology and absence of HPV. During the follow-up, 20 P/R were detected, 16 (15.2%) of them being high-grade squamous intraepithelial lesions (7 CIN II and 9 CIN III). The combination of endocervical cytology and HPV determination in the remaining cervix seems to be a good strategy to predict the risk of SIL after conization. The probability of P/R can be estimated based on the results of these 2 variables. The negativity of HPV determination together with a negative endocervical cytology guarantees enough security and a favorable evolution.

Macrophages display proinflammatory phenotypes in the eutopic endometrium of women with endometriosis with relevance to an infectious etiology of the disease.

OBJECTIVE: To phenotype transcriptomically M1 macrophages (Mϕ1) and M2 macrophages (Mϕ2) in the endometrium of women with endometriosis. DESIGN: Prospective experimental study. SETTING: University research laboratory. PATIENT(S): Six women with endometriosis and five controls without disease, in the secretory phase of the menstrual cycle. INTERVENTION(S): Mϕ1, Mϕ2, uterine natural killer, and T regulatory cells were isolated from human endometrium using a uniquely designed cell-specific fluorescence activating cell sorting panel. Transcriptome profiles were assessed by RNA high sequencing, bioinformatics, and biological pathway analyses. MAIN OUTCOMES MEASURE(S): Differential gene expression between Mϕ1 and Mϕ2 in women with and without endometriosis and in Mϕ1 versus Mϕ2 in each group was determined and involved different biologic and signaling pathways. RESULT(S): Flow cytometry analysis showed no significant differences in total numbers of leukocytes between control and endometriosis groups, although Mϕ1 were higher in the endometriosis group versus controls. Statistical transcriptomic analysis was performed only in Mϕ1 and Mϕ2 populations due to larger sample sizes. Bioinformatic analyses revealed that in women with endometriosis, endometrial Mϕ1 are more proinflammatory than controls and that Mϕ2 paradoxically have a proinflammatory phenotype. CONCLUSION(S): As Mϕ are phenotypically plastic and their polarization state depends on their microenvironment, the altered endometrial environment in women with endometriosis may promote endometrial Mϕ2 polarization and an Mϕ1 proinflammatory phenotype. Moreover, aberrant phenotypes of Mϕ may contribute to abnormal gene expression of the eutopic endometrium and a proinflammatory environment in women with endometriosis relevant to the pathophysiology of the disease and compromised reproductive outcomes.

[New therapeutic strategies for human papillomavirus related anogenital lesions in HIV patients: highly active antiretroviral therapy and HPV vaccines]. / Nuevas estrategias terapéuticas para las lesiones anogenitales relacionadas con el virus del papiloma humano en pacientes con infección por el VIH: tratamiento antirretroviral de gran actividad y vacunas anti-VPH.

This review focuses on the recent therapeutic advances that may affect the management of neoplastic anogenital human papillomavirus (HPV)-related lesions in human immunodeficiency virus patients: highly active antiretroviral therapy (HAART) and HPV vaccines. HAART shows limited benefit on the incidence of high grade intraepithelial lesions and cancer in cervix, vulva and anus. On the other hand, it seems to raise discretely the spontaneous regression rates of cervical low grade lesions -cervical intraepithelial neoplasia (CIN) grade I- and condylomas, as well as the regression after treatment of CIN II-III. The benefit of HAART in squamous intraepithelial lesion seems to be modest, mostly due to the improvement of the immune status. The usefulness of DNA-HPV in HIV is not well established. HPV vaccines represent a mid-term new possibility of prevention for these lesions according to the high effectiveness shown in clinical trials, although the lack of data about effectiveness and security in HIV patients restrict its application. Second generation vaccines, still to be developed, might better adapt the specific needs of these patients.

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.

Aberrant expression of epithelial leucine-rich repeat containing G protein-coupled receptor 5-positive cells in the eutopic endometrium in endometriosis and implications in deep-infiltrating endometriosis.

OBJECTIVE: To characterize leucine-rich repeat containing G protein-coupled receptor 5-positive (LGR5+) cells from the endometrium of women with endometriosis. DESIGN: Prospective experimental study. SETTING: University hospital/fertility clinic. PATIENT(S): Twenty-seven women with endometriosis who underwent surgery and 12 healthy egg donors, together comprising 39 endometrial samples. INTERVENTION(S): Obtaining of uterine aspirates by using a Cornier Pipelle. MAIN OUTCOMES MEASURE(S): Immunofluorescence in formalin-fixed paraffin-embedded tissue from mice and healthy and pathologic human endometrium using antibodies against LGR5, E-cadherin, and cytokeratin, and epithelial and stromal LGR5+ cells isolated from healthy and pathologic human eutopic endometrium by fluorescence-activated cell sorting and transcriptomic characterization by RNA high sequencing. RESULT(S): Immunofluorescence showed that LGR5+ cells colocalized with epithelial markers in the stroma of the endometrium only in endometriotic patients. The results from RNA high sequencing of LGR5+ cells from epithelium and stroma did not show any statistically significant differences between them. The LGR5+ versus LGR5- cells in pathologic endometrium showed 394 differentially expressed genes. The LGR5+ cells in deep-infiltrating endometriosis expressed inflammatory markers not present in the other types of the disease. CONCLUSION(S): Our results revealed the presence of aberrantly located LGR5+ cells coexpressing epithelial markers in the stromal compartment of women with endometriosis. These cells have a statistically significantly different expression profile in deep-infiltrating endometriosis in comparison with other types of endometriosis, independent of the menstrual cycle phase. Further studies are needed to elucidate their role and influence in reproductive outcomes.