Is neonatal uterine bleeding involved in the pathogenesis of endometriosis as a source of stem cells?

Is Neonatal Uterine Bleeding Involved in Early-Onset Endometriosis?

BACKGROUND

There has been considerable progress in our understanding of endometriosis, but its pathophysiology remains uncertain. Uncovering the underlying mechanism of the rare instances of endometriosis reported in early postmenarcheal years and in girls before menarche can have wide implications.

METHODS

We conducted a literature review of all relevant articles on Medline.

RESULTS

In the review, we explore the pathogenetic theories of premenarcheal endometriosis, the role of retrograde menstruation in the adult and its potential role in early-onset disease, as well as the factors that argue against the existence of a link between early-onset endometriosis (EOE) and neonatal uterine bleeding (NUB).

CONCLUSIONS

As with endometriosis in adult women, the pathogenesis of early-onset disease remains unclear. A link between NUB and EOE is plausible, but there are considerable challenges to collating supporting evidence. The state of our understanding of early uterine development and of the pathophysiology of NUB leaves many unknowns that need exploration. These include proof of the existence of viable endometrial cells or endometrial mesenchymal stem cells in NUB, their passage to the pelvic cavity, their possible response to steroids, and whether they can reside within the pelvic cavity and remain dormant till menarche.

Omics-based novel strategies in the diagnosis of endometriosis

Endometriosis, an enigmatic and chronic disorder, is considered a debilitating condition despite being benign. Globally, this gynecologic disorder affects up to 10% of females of reproductive age, impacting almost 190 million individuals. A variety of genetic and environmental factors are involved in endometriosis development, hence the pathophysiology and etiology of endometriosis remain unclear. The uncertainty of the etiology of the disease and its complexity along with nonspecific symptoms have led to misdiagnosis or lack of diagnosis of affected people. Biopsy and laparoscopy are referred to as the gold standard for endometriosis diagnosis. However, the invasiveness of the procedure, the unnecessary operation in disease-free women, and the dependence of the reliability of diagnosis on experience in this area are considered the most significant limitations. Therefore, continuous studies have attempted to offer a noninvasive and reliable approach. The recent advances in modern technologies have led to the generation of large-scale biological data sets, known as -omics data, resulting in the proceeding of the -omics century in biomedical sciences. Thereby, the present study critically reviews novel and noninvasive biomarkers that are based on -omics approaches from 2020 onward. The findings reveal that biomarkers identified based on genomics, epigenomics, transcriptomics, proteomics, and metabolomics are potentially able to diagnose endometriosis, predict prognosis, and stage patients, and potentially, in the near future, a multi-panel of these biomarkers will generate clinical benefits.

Neonatal uterine bleeding: Risk factors and its association with endometriosis-related symptoms later in life

OBJECTIVE

We examined the prevalence and risk factors in association with neonatal uterine bleeding (NUB) by retrospective search of contemporary and historical medical records and investigated the possible association between the history of NUB at birth and endometriosis-related symptoms later in life who are now young women.

STUDY DESIGN

This was a retrospective case-controlled cohort study and prospective evaluation of web-based questionnaire survey on symptoms related to endometriosis among young women born with and without NUB. Multiple regression analysis was performed incorporating various confounding variables that may influence the occurrence of NUB or the reporting of endometriosis symptoms later in life.

RESULTS

Among the 1093 female neonates born between 1996 and 2000, 105 of them had NUB, yielding with a prevalence of 9.6 %. Of the 807 female babies born between 2013 and 2017, 25 (3.1 %) had NUB. Multiple Logistic regression analysis indicated that younger age of the mother [odds ratio (OR) = 0.92, 95 % confidence interval (CI) = 0.85-1.00, P = 0.048] and longer gestational age of 39 weeks (OR = 3.04, 95 % CI = 1.43-6.45, P = 0.004) and of ≥ 40 weeks (OR = 4.54, 95 % CI = 2.20-9.39, P < 0.0001) of gestation were significantly associated with the occurrence of NUB. While the possibility of recall bias cannot be ruled out, newborn females who had a history of NUB appeared to complain of various endometriosis-related symptoms later in life during adulthood.

CONCLUSIONS

We confirmed the validity of the reported prevalence and risk factors of NUB. NUB indeed occurs with a prevalence of 3-10% during the historical and contemporary period. Longer gestational age and younger maternal age may be considered as high-risk factors for the occurrence of NUB. The clinical relevance of our findings remains to be elucidated. Future prospective studies, preferably with larger sample sizes and the inclusion of NUB cases after discharge from the hospital, may further illuminate some unresolved issues. We also need to confirm the endometriosis-related symptoms in women with and without history of NUB via more definitive diagnosis such as imaging and histology.

Deep Infiltrating Endometriosis in Adolescence: Early Diagnosis and Possible Prevention of Disease Progression

Endometriosis has a prevalence of 10% worldwide in premenopausal women. Probably, endometriosis begins early in the life of young girls, and it is commonly diagnosed later in life. The prevalence of deep infiltrating endometriosis (DIE) in adolescence is currently unknown due to diagnostic limits and underestimation of clinical symptoms. Dysmenorrhea is a common symptom in adolescents affected by DIE, often accompanied by dyspareunia and chronic acyclic pelvic pain. Ultrasonography-either performed transabdominal, transvaginal or transrectal-should be considered the first-line imaging technique despite the potential for missed diagnosis due to early-stage disease. Magnetic resonance imaging should be preferred in the case of virgo patients or when ultrasonographic exam is not accepted. Diagnostic laparoscopy is deemed acceptable in the case of suspected DIE not responding to conventional hormonal therapy. An early medical and/or surgical treatment may reduce disease progression with an immediate improvement in quality of life and fertility, but at the same time, painful symptoms may persist or even recur due to the surgery itself. The aim of this narrative review is to report the prevalence of DIE in adolescents, describe the pathogenetic theories and discuss the management in adolescent women, including the challenging road to diagnosis and the treatment alternatives.

Identification of central genes for endometriosis through integration of single-cell RNA sequencing and bulk RNA sequencing analysis

This study aimed to identify the key genes involved in the development of endometriosis and construct an accurate predictive model to provide new directions for the diagnosis and treatment of endometriosis. Using bioinformatics analysis, we employed the single-cell cell communication method to identify the key cell subtypes. By combining chip data and integrating differential analysis, WGCNA analysis, and the least absolute shrinkage and selection operator (LASSO) model, key genes were identified for immune infiltration and functional enrichment analyses. Cell communication analysis identified tissue stem cells as the key subtype. Differential analysis revealed 1879 differentially expressed genes, whereas WGCNA identified 357 module genes. The LASSO model further selects 4 key genes: Adipocyte Enhancer Binding Protein 1(AEBP1), MBNL1, GREM1, and DES. All 4 key genes showed significant correlations with immune cell content. Moreover, these genes were significantly expressed in single cells. The predictive model demonstrated good diagnostic performance. Through scRNA-seq, WGCNA, and LASSO methodologies, DES, GREM1, MBNL1, and AEBP1 emerged as crucial core genes linked to tissue stem cell markers in endometriosis. These genes have promising applications as diagnostic markers and therapeutic targets for endometriosis.

How to Manage Endometriosis in Adolescence: The Endometriosis Treatment Italian Club Approach

The evaluation of endometriosis in an adolescent girl is a challenging topic. The initial stage of the disease and the limited diagnostic instrument appropriate for the youth age and for its typical features can reduce the ability of the gynecologist. At the same time, missing a prompt diagnosis can delay the beginning of specific and punctual management of endometriosis, which could avoid a postponed diagnosis from 6 to 12 years, typical of adolescent girls complaining of dysmenorrhea. This article aimed to answer all the potential questions around the diagnosis and management of endometriosis in adolescents starting from a clinical case looking at the possible solution that is easily reproducible in the clinical practice.

In Memory of Ivo Brosens: Reflections on the Pathophysiology of Neonatal Uterine Bleeding

BACKGROUND

The occurrence of vaginal bleeding in early neonatal life has been observed for centuries and was considered a consequence of the sudden drop in circulating hormones following birth. As such, neonatal uterine bleeding was dismissed as having no clinical significance. Interest in the phenomenon was renewed when a new theory suggested a link between neonatal uterine bleeding (NUB) and accelerated endometrial maturation. This theory was based on the observation of a higher incidence of NUB in babies born post-term or after pregnancies complicated by intrauterine growth restriction, preeclampsia, or blood group incompatibility.

OBJECTIVE

The objective of this study was to review of available evidence on the pathogenesis of NUB.

METHOD

Review of available literature using Medline search (August 2022, no limit on start date or language) to identify articles that may link NUB with features of the uterus and/or endometrium.

OUTCOME

The fetal endometrial responses differ from that of the adult. In the fetus, the endometrium features progestogenic response only in a minority of cases. The endometrium in most newborn girls does not exhibit secretory or decidual changes which indicate lack of progesterone response. Most newborn girls do not have visible bleeding. Animal studies linked exogenous progestogen exposure during the period of organogenesis to poor endometrial gland development, progesterone resistance, and to alterations of reproductive performance. Although the fetal endometrium may not exhibit a full proliferative response, it is clearly sensitive to circulating estrogens. Molecular mechanisms involved in NUB may include "ontogenetic progesterone resistance."

CONCLUSION AND OUTLOOK

Endometrial development and its response to withdrawal of hormones at birth varies and may be affected by intrauterine stressors and gestational age. Factors that affect endometrial development during fetal life and in preterm neonates can have implications on future reproductive performance.

Is neonatal uterine bleeding responsible for early-onset endometriosis?

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

not applicable.

Acute Large Bowel Obstruction Caused by Endometriosis Requiring Sigmoidectomy

Large bowel obstruction (LBO) accounts for nearly 25% of all bowel occlusions. LBO is managed as a surgical emergency due to its increased risk of bowel perforation. Nearly, 2% to 4% of all surgical admissions are a result of LBO. The most common pathological development of LBO remains colonic malignancy, representing approximately 60% of cases. Other etiology includes abdominal adhesions, diverticulosis, hernia, inflammatory bowel disease (IBD), and in rare cases endometriosis. In this report, the patient is a 36-year-old female with an LBO, originally thought to be a complication of diverticulitis. However, it was confirmed that the obstruction was a result of endometriosis tissue adherence to the colonic wall narrowing the intestinal lumen. The patient presented to the emergency department (ED) with nausea, vomiting, and abdominal pain that started six weeks prior. In this case report, we will discuss the rare complication of endometriosis causing LBO, clinical presentation, diagnosis, and management.

Endometrial Stem/Progenitor Cells–Their Role in Endometrial Repair and Regeneration

The human endometrium is a remarkable tissue, undergoing ~450 cycles of proliferation, differentiation, shedding (menstruation), repair, and regeneration over a woman's reproductive lifespan. Post-menstrual repair is an extremely rapid and scar-free process, with re-epithelialization of the luminal epithelium completed within 48 h of initiation of shedding. Following menstruation, the functionalis grows from the residual basalis layer during the proliferative phase under the influence of rising circulating estrogen levels. The regenerative capacity of the endometrium is attributed to stem/progenitor cells which reside in both the epithelial and stromal cell compartments of the basalis layer. Finding a definitive marker for endometrial epithelial progenitors (eEPCs) has proven difficult. A number of different markers have been suggested as putative progenitor markers including, N-cadherin, SSEA-1, AXIN2, SOX-9 and ALDH1A1, some of which show functional stem cell activity in in vitro assays. Each marker has a unique location(s) in the glandular epithelium, which has led to the suggestion that a differentiation hierarchy exists, from the base of epithelial glands in the basalis to the luminal epithelium lining the functionalis, where epithelial cells express different combinations of markers as they differentiate and move up the gland into the functionalis away from the basalis niche. Perivascular endometrial mesenchymal stem cells (eMSCs) can be identified by co-expression of PDGFRβ and CD146 or by a single marker, SUSD2. This review will detail the known endometrial stem/progenitor markers; their identity, location and known interactions and hierarchy across the menstrual cycle, in particular post-menstrual repair and estrogen-driven regeneration, as well as their possible contributions to menstruation-related disorders such as endometriosis and regeneration-related disorder Asherman's syndrome. We will also highlight new techniques that allow for a greater understanding of stem/progenitor cells' role in repair and regeneration, including 3D organoids, 3D slice cultures and gene sequencing at the single cell level. Since mouse models are commonly used to study menstruation, repair and regeneration we will also detail the mouse stem/progenitor markers that have been investigated in vivo.

Diagnosis of endometriosis using endometrioma volume and vibrational spectroscopy with multivariate methods as a noninvasive method

Endometriomas are typically an advanced form of endometriosis that leads to the formation of scar tissue, adhesions, and an inflammatory reaction. There is no certain serum marker for the diagnosis of endometriosis. This study aims to research the correlation between the amount of peaks corresponding to proteins and lipids with the volume of endometrioma and determine the chemical structure of blood serum collected from women suffering from endometriosis patients with endometrioma and healthy subjects using Fourier Transform Infrared (FTIR) spectroscopy. FTIR spectroscopy is used as a non-invasive diagnostic technique for the discrimination of endometriosis women with endometrioma and control blood sera. The FTIR spectra of 100 serum samples acquired from 50 patients and 50 healthy individuals were used for this study. For this purpose, multivariate analyses such as Principal Component Analysis (PCA), Partial Last Square analysis (PLS) with Variables Importance in Projection (VIP), and probability models, were performed. Our results showed that FTIR range 1500 cm^-1 and 1700 cm^-1 and around 2700 cm^-1 - 3000 cm^-1, regions may be used for the diagnosis of endometriosis. Also, we find that proteins and lipids fraction increase with the volume of endometrioma. Moreover, PLS and VIP analysis suggested that lipids could be helpful in the diagnosis of endometriosis women with endometrioma.

Age-dependent phenotypes of ovarian endometriomas

Purpose

To analyze the characteristics of the ovarian endometrioma (OE) across the life span of a woman. In the past, the OE has traditionally been viewed as a single, monolithic disease. Today, there are emerging data indicating that OE phenotypes differ according to the age of the woman.

Method

A narrative review of original articles on OE indexed by PubMed.

Results

When appearing in infancy and early adolescence, OE may be the consequence of endometrial cells retrogradely shed with neonatal uterine bleeding. The post-menarcheal variant, manifesting itself during full adolescence, is singularly frequent in the presence of vaginal or uterine outflow obstructive anomalies. The typical and most frequent adult phenotype is characterized by increasing fibrosis and a tendency to progress; its mere presence exerts a detrimental effect on the surrounding healthy ovarian tissue. In postmenopause, an old lesion may be reactivated in the presence of exogenous or endogenous estrogens, or even be produced ex novo; rarely, it can spread to a variety of organs and structures and even degenerate causing malignancies.

Conclusions

Given the existence of these variants, it is important to agree on management guidelines that take into consideration these different phenotypes.

A History of Neonatal Uterine Bleeding and Its Significance

Bleeding in newborns and young girls fascinated writers for more than a millennium. Initially, there was confusion between neonatal bleeding, early menstruation due to precocious puberty, and hemorrhage due to disease. During the 19th century descriptions appeared of what is referred to today as ‘neonatal menstruation’ or ‘neonatal uterine bleeding’. By the turn of the century, Halban linked bleeding to active substances present during pregnancy and hypothesized that, while the maternal uterus reacts with decidua formation, the “weaker” fetal uterus reacts only with menstrual-like changes. Despite this clear description, several alternative theories endured for decades. Bleeding was believed to be due to a ‘catarrhal’ or neoplastic state of the genital tract, pulmonary circulatory disorder, congenital heart malformations, closure of the umbilical cord or affections of the intestine. During the 1950s, progesterone response and resistance were proposed to explain the pathogenesis of bleeding and its low incidence. The fetal endometrium is resistant to the high circulating progesterone. A decidual response is infrequent and results in menstrual shedding upon progesterone withdrawal after birth. Further research linked fetal stress consequent to pregnancy complications and post-maturity to increased incidence and preterm birth to reduced incidence of neonatal uterine bleeding.

Endometriosis in adolescent and young women

Endometriosis in adolescence represents a specific variant of the disease with its own characteristics and, in some cases, even a possibly different pathogenesis. It has its own clinical presentation, diagnostic and therapeutic modalities. The condition is not rare as once thought and certainly deserves attention in view of increasing evidence of its likely progressive nature. Numerous theories for Its pathogenesis have been formulated and they have been divided into two main categories: the 'in-situ' and the 'transplantation' hypotheses. Clinical manifestations include as the prevailing symptom a persistent chronic pelvic pain, despite medical treatment, manifested under various forms: dysmenorrhea, acyclic chronic pain, acute abdominal pain and migraines. These symptoms can substantially affect the quality of life on an adolescent. At histopathology, adolescent endometriosis is characterized by a high proportion of subtle, clear, red or vesicular implants and by the rarity of deep nodules. Frequently, the picture includes ovarian endometriomas. In some adolescent girls, lesions may regress or even disappear, probably through immune suppression; in others, chronic stress, unhealthy diet or lifestyle such as high-fat diet, may accelerate lesional progression and cause symptoms. Classically, management of adolescent endometriosis has been centered on attempts to treat dysmenorrhea; today both medical and surgical modalities have the potential to improve quality of life, alleviate symptoms, prevent the development of more severe disease and minimize risks for future fertility in adolescents. Nonetheless, at present, medical treatments are considered the first line of interventions in treating young women.

Neonatal Uterine Bleedings: An Ignored Sign but a Possible Cause of Early-Onset Endometriosis - A Systematic Review

OBJECTIVE

Based on the hypothesis that neonatal uterine bleedings (NUB), occurring mostly in the first week after birth, could represent a pathogenetic mechanism for early-onset endometriosis, this systematic review (SR) was undertaken to evaluate the prevalence and screening strategies used to assess and quantify NUB.

DESIGN

Both a SR and a sample literature search in PubMed and Embase were conducted to gather information on NUB prevalence and screening techniques. This was performed by an information specialist. Only full-text articles regarding the assessment of NUB in neonates in the first 2 weeks after birth were included. No limit on language or publication data was used.

MATERIALS AND METHODS

The SR was registered in PROSPERO (CRD42019138121). Data was first assessed for eligibility on title and abstract by 2 blinded review authors. Any disagreements were discussed with a third reviewer if necessary. Subsequently, full-text articles were read and assessed for quality using the Cochrane Collaboration Handbook.

RESULTS

Out of 1,988 articles in the systematic search, 10 relevant articles were selected, of which 8 were identified through the systematic search and 2 were found through other sources. The sample search of 4,445 articles did not bring up relevant articles. Results were not comparable due to the heterogeneity of screening techniques, although data showed consensus. The prevalence of visible bleeding ranged from 3.3 to 53.8% and the prevalence of occult bleeding from 25.4 to 96.7%. The occurrence was the highest between the 3rd and 7th day postpartum (PP) and the bleeding lasted for 3-4 days on average. Various screening techniques for detecting NUB were found in the literature, including the use of hemoglobin detection devices (such as Hemastix) in the vaginal vestibulum, comparison of diapers with stains of known volume, colposcopy, and ultrasonography.

CONCLUSION

The reported prevalence of NUB varies considerably, with a consistent occurrence between the 3rd and the 7th day PP. Literature to assess NUB is dated. The techniques are poorly described and heterogeneous. Future research should focus on prospective cohort studies in order to attempt to correlate NUB cases to (early-onset) endometriosis.

Inflammation to Infertility: Panoramic View on Endometriosis

Endometriosis is a disease caused by the implantation of endometrial glands and stroma outside the uterine cavity. It affects 10% of the reproductive-age women this means that 190 million women are affected worldwide. The definitive diagnosis requires surgical exploration or a laparoscopy which is of a high expense. The pathogenesis of the disease is heterogeneous and poorly understood despite the progress in the research field. Infertility is one of the main symptoms of Endometriosis. The mechanism behind this remains unclear. Literature suggests that Endometriosis reduces implantation capacity, increases the risk of pregnancy loss, and causes anatomical obstruction imposed by endometriotic lesions. The disease has a high burden to it by decreasing the quality of women's life and imposing negative consequences for their productivity, social life, and emotional wellbeing. Since inflammation is considered the hallmark of endometriosis, it is worth looking at the mechanism of how inflammation is linked to infertility in endometriosis patients. In this study, we summarized the recent finding of how inflammation can affect oocyte, endometrium, hormones, and sperm.

Endometriosis-Associated Macrophages: Origin, Phenotype, and Function

Endometriosis is a complex, heterogeneous, chronic inflammatory condition impacting ~176 million women worldwide. It is associated with chronic pelvic pain, infertility, and fatigue, and has a substantial impact on health-related quality of life. Endometriosis is defined by the growth of endometrial-like tissue outside the uterus, typically on the lining of the pelvic cavity and ovaries (known as "lesions"). Macrophages are complex cells at the center of this enigmatic condition; they are critical for the growth, development, vascularization, and innervation of lesions as well as generation of pain symptoms. In health, tissue-resident macrophages are seeded during early embryonic life are vital for development and homeostasis of tissues. In the adult, under inflammatory challenge, monocytes are recruited from the blood and differentiate into macrophages in tissues where they fulfill functions, such as fighting infection and repairing wounds. The interplay between tissue-resident and recruited macrophages is now at the forefront of macrophage research due to their differential roles in inflammatory disorders. In some cancers, tumor-associated macrophages (TAMs) are comprised of tissue-resident macrophages and recruited inflammatory monocytes that differentiate into macrophages within the tumor. These macrophages of different origins play differential roles in disease progression. Herein, we review the complexities of macrophage dynamics in health and disease and explore the paradigm that under disease-modified conditions, macrophages that normally maintain homeostasis become modified such that they promote disease. We also interrogate the evidence to support the existence of multiple phenotypic populations and origins of macrophages in endometriosis and how this could be exploited for therapy.

Endometriosis

Pelvic endometriosis is a complex syndrome characterized by an estrogen-dependent chronic inflammatory process that affects primarily pelvic tissues, including the ovaries. It is caused when shed endometrial tissue travels retrograde into the lower abdominal cavity. Endometriosis is the most common cause of chronic pelvic pain in women and is associated with infertility. The underlying pathologic mechanisms in the intracavitary endometrium and extrauterine endometriotic tissue involve defectively programmed endometrial mesenchymal progenitor/stem cells. Although endometriotic stromal cells, which compose the bulk of endometriotic lesions, do not carry somatic mutations, they demonstrate specific epigenetic abnormalities that alter expression of key transcription factors. For example, GATA-binding factor-6 overexpression transforms an endometrial stromal cell to an endometriotic phenotype, and steroidogenic factor-1 overexpression causes excessive production of estrogen, which drives inflammation via pathologically high levels of estrogen receptor-β. Progesterone receptor deficiency causes progesterone resistance. Populations of endometrial and endometriotic epithelial cells also harbor multiple cancer driver mutations, such as KRAS, which may be associated with the establishment of pelvic endometriosis or ovarian cancer. It is not known how interactions between epigenomically defective stromal cells and the mutated genes in epithelial cells contribute to the pathogenesis of endometriosis. Endometriosis-associated pelvic pain is managed by suppression of ovulatory menses and estrogen production, cyclooxygenase inhibitors, and surgical removal of pelvic lesions, and in vitro fertilization is frequently used to overcome infertility. Although novel targeted treatments are becoming available, as endometriosis pathophysiology is better understood, preventive approaches such as long-term ovulation suppression may play a critical role in the future.

Endometriosis: advances and controversies in classification, pathogenesis, diagnosis, and treatment

Endometriosis is an enigmatic disease that could start at birth. Its pathogenesis is supported by different theories. Accumulating facts relate it to a multigenic disorder. In this review of recent publications, the principal symptoms of the disease, pain and infertility, as well as its pathogenesis, diagnosis, and classification will be addressed. Endometriosis presents three main variants: superficial peritoneal disease, deep infiltrating endometriosis, and ovarian endometriomas. The management of the disease, surgery, and medical and alternative therapies will be discussed. Special reference will be made to the quality of surgery and how to understand patients with endometriosis and endometriosis.

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.

Müllerianosis, Endocervicosis, and Endosalpingiosis of the Urinary Tract: A Literature Review

INTRODUCTION AND HYPOTHESIS

We reviewed reported cases of endocervicosis, endosalpingiosis, and müllerianosis of the bladder or ureters in women in order to highlight these conditions as distinct from endometriosis or adenomyosis.

METHODS

Medline and Scopus searches of all cases published till the October 1, 2017. All retrieved references were searched manually to identify relevant articles.

RESULTS

Twenty-six articles reported endocervicosis. These included 37 cases described by the authors as endocervicosis of the bladder. We identified 7 case reports of bladder endosalpingiosis. There were 26 publications including 27 cases of müllerianosis of the bladder and 3 cases affecting the lower ureter. Literature descriptions are limited but available accounts do not point to features that uniquely distinguished these conditions. Affected women tended to be older, and in many cases, there was a possible relation to past surgery and particularly to hysterectomy and caesarean sections. Many cases were reported in postmenopausal women. Local excision was sufficient in most cases.

CONCLUSION

The etiology of these conditions remains speculative, but case reports raise a possible link to pelvic surgery. There is a need for more detailed accounts of these lesions, which should be considered in the differential diagnosis of pre- and postmenopausal women with pelvic pain, dyspareunia, lower abdominal pain or discomfort, dysuria, frequency, or hematuria.

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.

Progress in the diagnosis and management of adolescent endometriosis: an opinion

Increasing evidence indicates that early onset endometriosis (EOE), starting around menarche or early adolescence, may have an origin different from the adult variant, originating from neonatal uterine bleeding (NUB). This implies seeding of naïve endometrial progenitor cells into the pelvic cavity with NUB; these can then activate around thelarche. It has its own pathophysiology, symptomatology and risk factors, warranting critical management re-evaluation. It can also be progressive, endangering future reproductive capacity. This variant seems to be characterized by the presence of ovarian endometrioma. Today, the diagnosis of endometriosis in young patients is often delayed for years; if rapidly progressive, it can severely affect pelvic organs, even in the absence of serious symptoms. Given the predicament, great attention must be paid to symptomatology that is often non-specific, justifying a search for new, simple, non-invasive markers of increased risk. Better use of modern imaging techniques will aid considerably in screening for the presence of EOE. Traditional laparoscopy should be limited to cases in which imaging gives rise to suspicion of severity and a stepwise, minimally invasive approach should be used, followed by medical treatment to prevent recurrence. In conclusion, EOE represents a condition necessitating early diagnosis and stepwise management, including medical treatment.

Neonatal uterine bleeding as a biomarker for reproductive disorders during adolescence: a worldwide call for systematic registration by nurse midwife

Neonatal uterine bleeding (NUB) occurs in approximately 5% of newborns and is generally considered to be of little clinical significance. However, the real clinical importance of this condition and its long-term implications remain to be determined. The reason why NUB is rare despite high circulating levels of progesterone can be attributed to a progesterone resistance present in a majority of neonates. Recent work indicates that NUB represents a significant biomarker for events that can occur later-on during adolescence. Indeed, clinical studies have shown that "neonatal menstruation" constitutes a sign of fetal distress during late pregnancy, reflecting a stage of endometrium development that may subsequently have an impact on the reproductive life of the adolescent and the young adult. Via retrograde flow, NUB can cause endometrial stem/progenitor cells to arrive into the pelvic cavity and survive there, dormant underneath the peritoneal surface, until menarche activates them. Indeed, there is both clinical and epidemiological evidence of a link between NUB and adolescent endometriosis. In addition, if progesterone resistance persists till the onset of menarche, in case of an early teen pregnancy, it can result in a disorder of deep placentation. Therefore, we propose that NUB should be carefully recorded so that prospective studies can examine its links with reproductive disorders in adolescence and beyond.

Promoting awareness of neonatal menstruation

Neonatal uterine bleeding (NUB) has been carefully studied in the past through case reports, small series, clinical cohort studies, pathology investigations of fetal and neonatal. Following a historical recount, this review summarizes biological mechanisms conditioning NUB, starting from the persistence till birth of an 'ontogenetic progesterone resistance' (OPR), causing decreased responsiveness of target tissues to bioavailable progesterone. Several pregnancy-related conditions, such as preeclampsia, fetal growth restriction, prematurity, post-maturity and even Rhesus or ABO incompatibility, influence the occurrence of NUB. It seems therefore that the phenomenon is precipitated by chronic fetal distress. When present, OPR may persists until telarche; as a consequence, if pregnancy occurs in early teenage, the disorder known as "defective deep placentation" may ensue, increasing the risk of obstetrical syndromes. In the presence of NUB, retrograde shedding into the peritoneal cavity of endometrial stem/progenitor and niche cells may occur. There, given the right environment, these cells can survive and become activated at the time of telarche, causing the specific phenotype of early-onset endometriosis. In conclusion, neonatal menstruation is a fetal distress indicator and can alter the incidence of a variety of pathological conditions later in life. For this reason, it should be carefully recorded and the parents informed.

Adult Stem Cells in the Pathogenesis and Treatment of Endometriosis

The human endometrium is a dynamic tissue that undergoes approximately 400 cyclical episodes of proliferation, differentiation, shedding, and regeneration in a woman's reproductive lifespan. The regenerative capacity of human endometrium is likely mediated by adult stem cells. At the cellular level, endometrial mesenchymal stem/stromal cells, located in both the functionalis and basalis layers, support regeneration of the stromal vascular compartment and epithelial progenitor cells, postulated to reside in the basalis epithelium, likely regenerate the glands. Bone marrow adult stem cells, including endothelial progenitor cells, may also participate. Endometriosis can be considered an endometrial proliferative disorder due to dysregulation of the cellular and molecular regenerative processes.

Endometriosis is primarily thought to occur via retrograde menstruation of endometrial debris. It is postulated that endometrial stem/progenitor cells, which have been identified in menstrual blood, are shed into the peritoneal cavity where they adhere to pelvic organs and initiate endometriotic lesions. The homing of bone-marrow-derived adult stem cells to endometriotic lesions is thought to drive progression of the disease.

New drug therapies are urgently required for the treatment of endometriosis due to frequent disease recurrence with current surgical or medical treatments. Medications directly targeting endometrial stem/progenitor cells during menstruation, or following surgery, or targeting bone marrow cell trafficking, are potential targets for future therapies to manage disease initiation and progression.

In this review, we will summarize the current literature on adult stem cell contributions to the development of endometriosis and will then examine the current potential therapies that may target endometrial stem/progenitor cells.

Endometrioma in Adolescents and Future Reproductive Health

There continues to be debate over the nature and progression of ovarian endometriomas in adolescence due to the possibility that they may have a different origin and to the impossibility to be able to predict progress.

The hypothesis of a different origin traces its roots in the phenomenon called “neonatal menstruation” (NUB), occurring in approximately 5% of newborn. The retrograde shedding of neonatal endometrium may contain progenitor cells and stroma that may lie dormant under the peritoneal surface until being activated when estrogens begin to rise.

In teenagers, ovarian endometriomas are often preceded by highly angiogenic implants in the fossa ovarica, with adhesion formation resulting in the invagination of the ovarian cortex and the creation of a pseudocyst.

Use of imaging techniques makes it possible to diagnose even small endometriomas. This is vital to their management, since there is evidence that the disease in an adolescent represents a severe condition, with tendency to progression. In addition, if intervention is decided, the first surgical procedure can determine the ultimate outcome of her reproductive life, because there is a significantly higher risk of inadvertently removing ovarian tissue in the presence of an endometrioma than of other ovarian pathologies. For this reason, techniques avoiding additional trauma to the ovary should be preferred and those who wish to become pregnant should attempt conception as soon as possible; if pregnancy is not sought, hormonal therapy is strongly advised.

Finally, young age at diagnosis may constitute a pivotal factor in considering fertility preservation.

Endometrial stem/progenitor cells: the first 10 years

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The potential perinatal origin of placentation disorders in the young primigravida

The fetus is exposed to high plasma concentrations of unbound estrogens and progesterone throughout pregnancy. However, secretory or decidual changes in the fetal uterus occur relatively infrequently before birth, suggesting a variable endometrial progesterone response at the time of birth. Arguably, partial progesterone resistance that persists into adolescent years may compromise the physiological transformation of the spiral arteries and predispose for defective placentation in the case of pregnancy. Decidualization of the endometrial stromal compartment and junctional zone myometrium precedes trophoblast invasion. It represents the first step in the process of spiral artery remodeling needed to establish effective uteroplacental blood flow by midpregnancy. The major obstetric syndromes caused by impaired placental bed spiral artery remodeling are prevalent in teenage pregnancies, including preeclampsia, fetal growth restriction, and spontaneous preterm labor. Preconditioning of the uterus in response to cyclic menstruation during adolescence may be critical to achieve full uterine responsiveness to hormonal cues. Understanding the mechanisms of functional maturation of the uterus during the early reproductive years may yield novel insights into the major obstetric syndromes.

Ovarian endometrioma in the adolescent: a plea for early-stage diagnosis and full surgical treatment

The incidence and severity of endometriosis in adolescent are comparable with the incidence in adult women. The mean delay between the onset of symptoms and the final diagnosis varies between 6.4 and 11.7 years. The longer the diagnosis is delayed, the more the endometriosis can progress to a more severe stage certainly in the group of patients with pelvic pain. The evolution of endometriosis and its progressivity are not predictable, and the severity of the disease is not directly related to the degree of pain. Endometriotic cysts have a detrimental effect on the ovarian reserve by the evolution in time and the surgical excision technique. Already, in small endometriotic cysts (<4 cm), loss of follicular reserve is present together with the formation of fibrosis in the cortex of the ovary. Early diagnosis of endometriosis in the adolescent deserves our full attention. Non-invasive imaging techniques like 2-D and 3-D ultrasound are helpful in the early diagnosis. Early ablative surgery is recommendable. Although laparoscopy is traditionally recommended, transvaginal laparoscopy has been shown to be most effective in ablating endometriomas with a maximum diameter of 3 cm. Early detection and intervention will contribute to a better quality of life in these adolescents and also to a lower damage of the ovarian tissue by a less invasive ablative surgery.

Theories on the pathogenesis of endometriosis

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

Endometriosis in adolescents is a hidden, progressive and severe disease that deserves attention, not just compassion

Endometriosis in the adolescent has, in recent years, been discovered to be a challenging problem in gynaecology. Although the pain may start at a young age, even before the onset of menstruation, the diagnosis by laparoscopy is almost always postponed for several years, by which time destructive lesions have affected the tubo-ovarian structures and severely compromised fecundability. Several factors may play a role, but one important reason for this disease progression is likely to be the delay in diagnosis. Therefore, transvaginal ultrasounds and transvaginal access with a less invasive needle endoscopy are recommended for exploration of the pelvis, diagnosis of endometriosis and treatment at an early stage before severe lesions develop.