Endometrial organoids derived from Mayer-Rokitansky-Küster-Hauser syndrome patients provide insights into disease-causing pathways

Prevalence of endometriosis in Mayer-Rokitansky-Küster-Hauser syndrome variants: a systematic review and meta-analysis

STUDY QUESTION

In patients with Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS; population), is the presence of functional endometrium (FE) in uterine remnants (URs) (exposure), compared with the absence of FE in UR/absence of UR (comparison), associated with a higher prevalence of endometriosis (outcome)?

SUMMARY ANSWER

The aggregate prevalence of endometriosis was considerably higher in MRKHS patients with FE (MRKHSFE+) than in those without FE (MRKHSFE-).

WHAT IS KNOWN ALREADY

The pathogenesis of endometriosis is not fully understood. The finding of pelvic endometriosis in patients with MRKHS is one of the main objections to the retrograde menstruation (RM) hypothesis. The recent advent of high-resolution ultrasonography and magnetic resonance imaging (MRI) allowed the reliable preoperative identification of FE concealed within UR, and histopathological examination after UR removal is no longer the only means of verifying the presence of a mucosal component. A similar prevalence of endometriosis in MRKHSFE+ and MRKHSFE- patients, as assessed by preoperative ultrasound (US) and/or MRI, would essentially rule out the RM/implantation theory, whereas a substantially higher prevalence of endometriosis in MRKHSFE+ than in MRKHSFE- patients would challenge the embryonic remnants/coelomic metaplasia hypothesis.

STUDY DESIGN, SIZE, DURATION

This systematic review was restricted to full-length, English-language articles published in peer-reviewed journals between 1 January 1980 and 1 June 2024. The electronic PubMed and Embase databases were searched in June 2024. The keyword 'endometriosis' was used in combination with 'Mayer-Rokitansky-Küster-Hauser syndrome', 'Müllerian agenesis', 'uterine agenesis', 'vaginal agenesis', 'Müllerian anomalies', and 'female genital malformations'. References from relevant publications were screened, and PubMed's 'similar articles' and 'cited by' functions were used.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Studies were selected if they reported the presence or absence of FE within UR investigated by preoperative US or MRI or histology after surgical removal, and the presence or absence of surgically confirmed endometriosis. Case series and case reports were deemed eligible for inclusion. Studies not specifically stating the intent to search for the presence of endometrium within UR, or not reporting the results of ultrasonography or MRI, or histological examinations were excluded. Two reviewers independently abstracted data. The risk of bias was assessed using a tool specifically devised to ascertain the methodological quality of case series and case reports.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 102 studies (29 case series and 73 case reports), comprising 666 MRKHS patients in whom the presence or absence of FE was verified were included. Endometriosis was detected in 71 participants (10.7%; 95% CI, 8.5-13.2%), and its prevalence was 8.6% (51/593; 95% CI, 6.6-11.2%) in case series and 27.4% (20/73; 95% CI, 18.4-38.6%) in case reports (P<0.0001). When considering only the 19 case series with ≥10 participants, the proportion of MRKHS patients with endometriosis was 3.4% (41/1219; 95% CI, 2.5-4.5%). Among the 71 MRKHS patients with endometriosis, 64 had coexisting FE, and only seven had no evidence of FE within UR or did not have UR. The proportion of patients with endometriosis was 32.0% in the subgroup with FE (64/200; 95% CI, 25.9-38.8%) and 1.5% (7/466; 95% CI, 0.7-3.1%) in the subgroup without FE within UR/without UR. At meta-analysis considering case series, the overall prevalence estimates of endometriosis in patients with and without FE were, respectively, 16.8% (95% CI, 1.8-38.5%) and 0% (95% CI, 0-0%). In order to evaluate the association between FE and endometriosis we also conducted a meta-analysis that included case series reporting both FE+ and FE- patients. A significantly increased risk of endometriosis was observed in MRKHSFE+ patients compared with MRKHSFE- patients (overall odds ratio estimate was 12.0; 95% CI, 5.1-28.3%). The quality of the evidence score was higher in the case series subgroup (median score, 4 points; interquartile range, 3-5 points) than in the case reports subgroup (median score, 3 points; interquartile range, 2-4 points).

LIMITATIONS, REASON FOR CAUTION

Due to the uncontrolled and non-experimental study design, case series and case reports are associated with an increased risk of selection, performance, detection, attrition, and reporting bias. In the seven cases of endometriosis in patients purportedly without detected FE, a preoperative MRI was not systematically performed or erroneous findings were reported, the anatomical description at surgery was incomplete or inconsistent, the histopathological diagnosis of endometriosis was missing or questionable, and precise microscopic features were not always described. Whether FE (exposure) was truly absent in all these cases and/or whether all lesions diagnosed as endometriosis (outcome) were indeed true disease, seems uncertain.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings should raise awareness of the importance of accurately assessing and reporting the presence or absence of FE within UR, and of systematically performing biopsies of visually diagnosed endometriosis in MRKHS patients. Considering the high risk of bias, the detection of endometriosis in MRKHS patients allegedly without FE in the few relevant case reports published in the last four decades should no longer be interpreted tout court as proof for the coelomic metaplasia/embryonic remnants theory.

STUDY FUNDING/COMPETING INTEREST(S)

No funding was received for this review. P.Ve. is a member of the Editorial Board of Human Reproduction Open, the Journal of Obstetrics and Gynaecology Canada, and the International Editorial Board of Acta Obstetricia et Gynecologica Scandinavica; has received royalties from Wolters Kluwer for chapters on endometriosis management in the clinical decision support resource UpToDate; and maintains both a public and private gynaecological practice. E.S. is Editor-in-Chief of Human Reproduction Open; discloses payments from Ferring for research grants and honoraria from Merck-Serono for lectures; and maintains both a public and private gynaecological practice. P.Vi. is Co-Editor-in-Chief of Journal of Endometriosis and Uterine Disorders. All other authors declare they have no conflict of interest.

REGISTRATION NUMBER

The study protocol was registered on PROSPERO (registration number, CRD42024512351).

Harnessing 2D and 3D human endometrial cell culture models to investigate SARS-CoV-2 infection in early pregnancy

Vertical transmission of SARS-CoV-2 during human pregnancy remains highly controversial as most studies have focused on the third trimester or the peripartum period. Given the lack of early trimester data, determining the prevalence of vertical transmission during early pregnancy and assessing the potential risks for fetal morbidity and mortality pose a challenge. Therefore, we analysed the impact of SARS-CoV-2 infection on an endometrial 3D spheroid model system. The 3D spheroids are capable of decidualization and express angiotensin-converting enzyme 2 (ACE2) as well as transmembrane protease serine 2 (TMPRSS2), rendering them susceptible to SARS-CoV-2 infection. Employing this 3D cell model, we identified that SARS-CoV-2 can infect both non-decidualized and decidualized endometrial spheroids. Infection significantly increased the chemokine Monocyte chemoattractant protein-1 (MCP-1) compared to non-infected spheroids. Decidualized spheroids exhibited upregulated Interleukin (IL)-8 levels. Furthermore, RNA sequencing revealed dysregulation of several genes involved in tissue-specific immune response, Fc receptor signalling, angiotensin-activated signalling and actin function. Gene expression changes varied between SARS-CoV-2 infected non-decidualized and decidualized spheroids and genes associated with the innate immune system (CD38, LCN2 and NR4A3) were dysregulated as a potential mechanism for immune evasion of SARS-CoV-2. Altogether, our study demonstrates that endometrial spheroids are a useful model to examine the clinical implications of SARS-CoV-2 vertical transmission, warranting further investigations.

Proof-of-Concept for Long-Term Human Endometrial Epithelial Organoids in Modeling Menstrual Cycle Responses

Endometrial disorders, such as infertility and endometriosis, significantly impact reproductive health, thus necessitating better models to study endometrial function. Current in vitro models fail to replicate the complexity of the human endometrium throughout the entire menstrual cycle. This study aimed to assess the physiological response of human endometrial organoids (hEOs) to in vitro hormonal treatments designed to mimic the hormonal fluctuations of the menstrual cycle. Endometrial biopsies from three healthy women were used to develop hEOs, which were treated over 28 days with three hormonal stimulation strategies: (1) estrogen only (E) to mimic the proliferative phase, (2) the addition of progesterone (EP) to simulate the secretory phase, and (3) the further addition of cAMP (EPC) to enhance the secretory functions of hEOs. Gene and protein expression were analyzed using qPCR, IHC, and ELISA. The hEOs exhibited proliferation, gland formation, and appropriate expression of markers such as E-cadherin and Ki67. The hormonal treatments induced significant changes in PR, HSD17B1, PAEP, SPP1, and other genes relevant to endometrial function, closely mirroring in vivo physiological responses. The prominent changes were observed in EPC-treated hEOs (week 4) with significantly high expression of uterine milk components such as glycodelin (PAEP) and osteopontin (SPP1), reflecting mid- to late-secretory phase physiology. This model successfully recapitulates human menstrual cycle dynamics and offers a promising platform for studying endometrial disorders and advancing personalized treatments in gynecology.

Landscape of human organoids: Ideal model in clinics and research

In the last decade, organoid research has entered a golden era, signifying a pivotal shift in the biomedical landscape. The year 2023 marked a milestone with the publication of thousands of papers in this arena, reflecting exponential growth. However, amid this burgeoning expansion, a comprehensive and accurate overview of the field has been conspicuously absent. Our review is intended to bridge this gap, providing a panoramic view of the rapidly evolving organoid landscape. We meticulously analyze the organoid field from eight distinctive vantage points, harnessing our rich experience in academic research, industrial application, and clinical practice. We present a deep exploration of the advances in organoid technology, underpinned by our long-standing involvement in this arena. Our narrative traverses the historical genesis of organoids and their transformative impact across various biomedical sectors, including oncology, toxicology, and drug development. We delve into the synergy between organoids and avant-garde technologies such as synthetic biology and single-cell omics and discuss their pivotal role in tailoring personalized medicine, enhancing high-throughput drug screening, and constructing physiologically pertinent disease models. Our comprehensive analysis and reflective discourse provide a deep dive into the existing landscape and emerging trends in organoid technology. We spotlight technological innovations, methodological evolution, and the broadening spectrum of applications, emphasizing the revolutionary influence of organoids in personalized medicine, oncology, drug discovery, and other fields. Looking ahead, we cautiously anticipate future developments in the field of organoid research, especially its potential implications for personalized patient care, new avenues of drug discovery, and clinical research. We trust that our comprehensive review will be an asset for researchers, clinicians, and patients with keen interest in personalized medical strategies. We offer a broad view of the present and prospective capabilities of organoid technology, encompassing a wide range of current and future applications. In summary, in this review we attempt a comprehensive exploration of the organoid field. We offer reflections, summaries, and projections that might be useful for current researchers and clinicians, and we hope to contribute to shaping the evolving trajectory of this dynamic and rapidly advancing field.

Genetics of Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome: advancements and implications

Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome is a congenital anomaly characterized by agenesis/aplasia of the uterus and upper part of the vagina in females with normal external genitalia and a normal female karyotype (46,XX). Patients typically present during adolescence with complaints of primary amenorrhea where the diagnosis is established with significant implications including absolute infertility. Most often cases appear isolated with no family history of MRKH syndrome or related anomalies. However, cumulative reports of familial recurrence suggest genetic factors to be involved. Early candidate gene studies had limited success in their search for genetic causes of MRKH syndrome. More recently, genomic investigations using chromosomal microarray and genome-wide sequencing have been successful in detecting promising genetic variants associated with MRKH syndrome, including 17q12 (LHX1, HNF1B) and 16p11.2 (TBX6) deletions and sequence variations in GREB1L and PAX8, pointing towards a heterogeneous etiology with various genes involved. With uterus transplantation as an emerging fertility treatment in MRKH syndrome and increasing evidence for genetic etiologies, the need for genetic counseling concerning the recurrence risk in offspring will likely increase. This review presents the advancements in MRKH syndrome genetics from early familial occurrences and candidate gene searches to current genomic studies. Moreover, the review provides suggestions for future genetic investigations and discusses potential implications for clinical practice.

A Cohort of 469 Mayer-Rokitansky-Küster-Hauser Syndrome Patients-Associated Malformations, Syndromes, and Heterogeneity of the Phenotype

The Mayer-Rokitansky-Küster-Hauser syndrome is characterized by aplasia of the uterus and upper two-thirds of the vagina. While it can appear as an isolated genital malformation, it is often associated with extragenital abnormalities, with little still known about the pathogenetic background. To provide an overview of associated malformations and syndromes as well as to examine possible ties between the rudimentary tissue and patient characteristics, we analyzed a cohort of 469 patients with MRKHS as well as 298 uterine rudiments removed during surgery. A total of 165 of our patients (35.2%) had associated malformations (MRKHS type II). Renal defects were the most common associated malformation followed by skeletal abnormalities. Several patients had atypical associated malformations or combined syndromes. Uterine rudiments were rarer in patients with associated malformations than in patients without them. Rudiment size ranged from 0.3 cm3 to 184.3 cm3 with a mean value of 7.9 cm3. Importantly, MRKHS subtype or concomitant malformations were associated with a different frequency of uterine tissue as well as a different rudiment size and incidence of endometrial tissue, thereby indicating a clear heterogeneity of the phenotype. Further research into the associated molecular pathways and potential differences between MRKHS subtypes is needed.

Using organoids to investigate human endometrial receptivity

The human endometrium is only receptive to an implanting blastocyst in the mid-secretory phase of each menstrual cycle. Such time-dependent alterations in function require intricate interplay of various factors, largely coordinated by estrogen and progesterone. Abnormal endometrial receptivity is thought to contribute to two-thirds of the implantation failure in humans and therefore significantly hindering IVF success. Despite the incontrovertible importance of endometrial receptivity in implantation, the precise mechanisms involved in the regulation of endometrial receptivity remain poorly defined. This is mainly due to a lack of proper in vitro models that recapitulate the in vivo environment of the receptive human endometrium. Organoids were recently established from human endometrium with promising features to better mimic the receptive phase. Endometrial organoids show long-term expandability and the capability to preserve the structural and functional characteristics of the endometrial tissue of origin. This three-dimensional model maintains a good responsiveness to steroid hormones in vitro and replicates key morphological features of the receptive endometrium in vivo, including pinopodes and pseudostratified epithelium. Here, we review the current findings of endometrial organoid studies that have been focused on investigating endometrial receptivity and place an emphasis on methods to further refine and improve this model.

Matrix scaffolds for endometrium-derived organoid models

The uterus-lining endometrium is essential to mammalian reproduction, receiving and accommodating the embryo for proper development. Despite its key role, mechanisms underlying endometrial biology (menstrual cycling, embryo interaction) and disease are not well understood. Its hidden location in the womb, and thereby-associated lack of suitable research models, contribute to this knowledge gap. Recently, 3D organoid models have been developed from both healthy and diseased endometrium. These organoids closely recapitulate the tissue's epithelium phenotype and (patho)biology, including in vitro reproduction of the menstrual cycle. Typically, organoids are grown in a scaffold made of surrogate tissue extracellular matrix (ECM), with mouse tumor basement membrane extracts being the most commonly used. However, important limitations apply including their lack of standardization and xeno-derivation which strongly hinder clinical translation. Therefore, researchers are actively seeking better alternatives including fully defined matrices for faithful and efficient growth of organoids. Here, we summarize the state-of-the-art regarding matrix scaffolds to grow endometrium-derived organoids as well as more advanced organoid-based 3D models. We discuss remaining shortcomings and challenges to advance endometrial organoids toward defined and standardized tools for applications in basic research and translational/clinical fields.