Endometriotic cell culture contamination and authenticity: a source of bias in in vitro research?

Particulate matter exposure induces adverse effects on endometrium and fertility via aberrant inflammatory and apoptotic pathways in vitro and in vivo

This study aimed to evaluate the adverse effects of particulate matter (PM) exposure on endometrial cells and fertility and to identify possible underlying mechanisms. Thirteen women (aged 15-52 years) were included in this study. Enrolled patients underwent laparoscopic surgery at Gangnam Severance Hospital between 1 January and 31 December 2021. For in vivo experiments, 36 female and nine male C57BL/6 mice were randomly divided into control(vehicle), low-dose(10 mg/kg/d), and high-dose exposure groups(20 mg/kg/d). PM was inhaled nasally for four weeks and natural mating was performed. NIST® SRM® 1648a was used for PM exposure. qRT-PCR, western blotting and Masson's trichrome staining were performed. PM treatment in human endometrial stromal cells induced inflammation with significant upregulation of IL-1β, p-NF-kB, and p-c-Jun compared to those of controls. Additionally, PM treatment significantly increased apoptosis in human endometrial stromal cells by downregulating p-AKT and upregulating p-p53/p53, Cas-3, BAX/Bcl-2, p-AMPK, and p-ERK. After PM treatment, the relative expression of IL-1β, IL-6, TNF-α, p-NF-κB, p-c-Jun, and p-Nrf2/Nrf2 significantly increased in murine endometrium compared to those of the controls. Expression of apoptotic proteins p53, p27, and Cas-3, was also significantly elevated in murine endometrium of the PM exposure group compared to that of the controls. A significant increase in expression of procollagen Ⅰ, and Masson's trichrome staining scores in the murine endometrium was noted after PM treatment. PM treatment significantly decreased ERα expression. After natural mating, all 3 female mice in the control group gave birth to 25 offspring (mean 8.1), whereas in the low-dose PM treatment group, two of three female mice gave birth to nine offspring (mean 4.5). No pregnant mice or offspring was present in the high-dose PM treatment group. PM exposure induces adverse effects on the endometrium through aberrant activation of inflammatory and apoptotic pathways and is associated with detrimental effects on murine fertility.

Endometriosis: Molecular Pathophysiology and Recent Treatment Strategies-Comprehensive Literature Review

Endometriosis is an enigmatic disease, with no specific cause or trigger yet discovered. Major factors that may contribute to endometriosis in the pelvic region include environmental, epigenetic, and inflammatory factors. Most experts believe that the primary mechanism behind the formation of endometrial lesions is associated with Sampson's theory of "retrograde menstruation". This theory suggests that endometrial cells flow backward into the peritoneal cavity, leading to the development of endometrial lesions. Since this specific mechanism is also observed in healthy women, additional factors may be associated with the formation of endometrial lesions. Current treatment options primarily consist of medical or surgical therapies. To date, none of the available medical therapies have proven effective in curing the disorder, and symptoms tend to recur once medications are discontinued. Therefore, there is a need to explore and develop novel biomedical targets aimed at the cellular and molecular mechanisms responsible for endometriosis growth. This article discusses a recent molecular pathophysiology associated with the formation and progression of endometriosis. Furthermore, the article summarizes the most current medications and surgical strategies currently under investigation for the treatment of endometriosis.

A newly improved method of primary cell culture: Tissue block with continuous adhesion subculture in skin fibroblast

BACKGROUND

Fibroblasts (FBs) have been widely used as a typical in vitro cell model for investigating the biological processes and cell pathophysiological mechanisms. However, FBs are prone to senescence in cell culture process after several passages. Thus, a new approach to cell culture is quite required to enhance the viability of cells.

OBJECTIVE

To explore a novel method of cell culture based on skin FBs.

METHODS

Dermal tissue blocks were obtained from BALB/c neonatal mice and randomly divided into experimental group and control group. The experimental group received the newly improved culture method, namely, continuous adherence subculture of tissue block (CASTB) method; while the traditional subculture method was applied in the control group. Cells at 1st, 5th and 10th passages were collected and identified by using histological/immunohistochemical and western blot analysis. Cellular viability, proliferation, senescence and apoptosis were analyzed through application of cell growth curve, CCK-8 assay, Ki67 assay, PCNA protein analysis, β-galactosidase staining, flow cytometry and western blot analysis.

RESULTS

Cells under two culture patterns exhibited spindle/irregular shape and vimentin positive expression. With the increase of passage times, the cellular growth rate in the control group gradually decreased, but no alterations emerged from the experimental group. CASTB method remarkably promoted cell growth and proliferation. Moreover, a greatly lower apoptosis and senescence tendency appeared in the experimental group than the control group with passages increasing.

CONCLUSION

The method of CASTB is superior to traditional subculture, offering a large number of primary FBs with higher efficiency and success rate and being worth of further popularization and application.

FDX1 enhances endometriosis cell cuproptosis via G6PD-mediated redox homeostasis

Cuproptosis is a new form of programmed cell death, which is associated with the mitochondrial TCA (tricarboxylic acid) cycle. But the functions of cuproptosis in endometriosis progression are still unknown. Here, we find that cuproptosis suppresses the growth of endometriosis cells and the growth of ectopic endometrial tissues in a mouse model. FDX1 as a key regulator in cuproptosis pathway could promote cuproptosis in endometriosis cells. Interestingly, FDX1 interacts with G6PD, and reduces its protein stability, which predominantly affects the cellular redox-regulating systems. Then, the reduced G6PD activity enhances cuproptosis via down-regulating NADPH and GSH levels. Collectively, our study demonstrates that FDX1 mediates cuproptosis in endometriosis via G6PD pathway, resulting in repression of endometriosis cell proliferation and metastasis.

PIK3CA mutation in endometriotic epithelial cells promotes viperin-dependent inflammatory response to insulin

Endometrial epithelia are known to harbor cancer driver mutations in the absence of any pathologies, including mutations in PIK3CA. Insulin plays an important role in regulating uterine metabolism during pregnancy, and hyperinsulinemia is associated with conditions impacting fertility. Hyperinsulinemia also promotes cancer, but the direct action of insulin on mutated endometrial epithelial cells is unknown. Here, we treated 12Z endometriotic epithelial cells carrying the PIK3CAH1047R oncogene with insulin and examined transcriptomes by RNA-seq. While cells naively responded to insulin, the magnitude of differential gene expression (DGE) was nine times greater in PIK3CAH1047R cells, representing a synergistic effect between insulin signaling and PIK3CAH1047R expression. Interferon signaling and the unfolded protein response (UPR) were enriched pathways among affected genes. Insulin treatment in wild-type cells activated normal endoplasmic reticulum stress (ERS) response programs, while PIK3CAH1047R cells activated programs necessary to avoid ERS-induced apoptosis. PIK3CAH1047R expression alone resulted in overexpression (OE) of Viperin (RSAD2), which is involved in viral response and upregulated in the endometrium during early pregnancy. The transcriptional changes induced by insulin in PIK3CAH1047R cells were rescued by knockdown of Viperin, while Viperin OE alone was insufficient to induce a DGE response to insulin, suggesting that Viperin is necessary but not sufficient for the synergistic effect of PIK3CAH1047R and insulin treatment. We identified interferon signaling, viral response, and protein targeting pathways that are induced by insulin but dependent on Viperin in PIK3CAH1047R mutant cells. These results suggest that response to insulin signaling is altered in mutated endometriotic epithelial cells.

Progranulin promotes proliferation, migration and invasion via the PI3K/Akt signalling pathway in a model of endometriosis

RESEARCH QUESTION

What are the levels of progranulin (PGRN) expression in primary endometrial stromal cells (ESC) and endometrial tissue in patients with endometriosis (EMS)? What is the role and mechanism of action of PGRN in EMS?

DESIGN

Endometrial tissue was collected from 30 patients, 15 with EMS (EMS group) and 15 without EMS (non-EMS group). PGRN expression in endometrial tissue and ESC was analysed by immunohistochemistry, immunofluorescence, western blotting and quantitative reverse transcription polymerase chain reaction. PGRN overexpression and silencing ESC were established with lentivirus to detect the effect on proliferation, invasion and migration. The relationship between PGRN and the phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) signalling pathway was verified by western blotting. A rescue assay was performed with PI3K inhibitor treatment.

RESULTS

The PGRN expression was significantly higher in EMS samples. PGRN up-regulation promoted proliferation (P = 0.007), migration (P = 0.002) and invasion (P < 0.001) of eutopic endometrial stromal cells (EUESC). The ratio of p-AKT/AKT was higher in the overexpression PGRN (ovPGRN) group than in the overexpression-NC (ovNC) group (P = 0.004). Silencing PGRN produced the opposite results, and LY2940002 addition reversed the effect of PGRN up-regulation on the proliferation, invasion and migration of EUESC.

CONCLUSIONS

PGRN might promote the proliferation, invasion and migration of EUESC via the PI3K/Akt signalling pathway. These preliminary in-vitro findings may present a new perspective and inspire further study of the mechanism of EMS.

The role of phoenixin in the proliferation and migration of ectopic epithelial cells in vitro

AIM

Endometriosis is one of the most common gynecologic diseases in women of reproductive age. The pathophysiology of endometriosis is still not fully understood. Phoenixin (PNX-14) is a newly discovered neuropeptide that regulates the hypothalamo-pituitary-gonadal (HPG) axis and reproductive functions. Recently, we reported that PNX-14, its precursor protein and receptor were expressed in human endometrium. Moreover, PNX-14 serum levels in endometriosis were reduced. This study aimed to evaluate the in vitro biological functions of physiological PNX-14 concentrations on the ectopic endometrium Z12 cells.

METHODS

The proliferation and migration of Z12 cells were assessed using the xCELLigence® RTCA DP system following 72 h of stimulation with 0.05 and 0.2 nM of PNX-14. GPR173 and small integral membrane protein 20 (SMIM20) gene expression was evaluated using quantitative polymerase chain reaction (qPCR) and the protein levels of GPR173 were analyzed using Western blot analysis.

RESULTS

PNX-14 at the concentration observed in the serum of patients with endometriosis (0.05 nM) reduced GPR173 and increased SMIM20 expression, while protein levels of GPR173 remained unchanged. Cell proliferation was increased by the 0.02 nM PNX-14- the concentration found in healthy subjects. The 0.2 nM of PNX-14 decreased SMIM20 expression with no change to GPR173 expression and reduced ectopic epithelial cell proliferation during the first 5 h after stimulation. However, at 72 h, the proliferation increased.

CONCLUSIONS

This study shows that PNX-14 at endometriosis specific concentration desensitized ectopic epithelium to PNX-14, and increased the expression of SMIM20 to restore the physiological levels of PNX-14.

ENDOCELL-Seud: a Delphi protocol to harmonise methods in endometrial cell culturing

In vitro

culturing of endometrial cells obtained from the uterine mucosa or ectopic sites is used to study molecular and cellular signalling relevant to physiologic and pathologic reproductive conditions. However, the lack of consensus on standard operating procedures for deriving, characterising and maintaining primary cells in two- or three-dimensional cultures from eutopic or ectopic endometrium may be hindering progress in this area of research. Guidance for unbiased in vitro research methodologies in the field of reproductive science remains essential to increase confidence in the reliability of in vitro models. We present herein the protocol for a Delphi process to develop a consensus on in vitro methodologies using endometrial cells (ENDOCELL-Seud Project). A steering committee composed of leading scientists will select critical methodologies, topics and items that need to be harmonised and that will be included in a survey. An enlarged panel of experts (ENDOCELL-Seud Working Group) will be invited to participate in the survey and provide their ratings to the items to be harmonised. According to Delphi, an iterative investigation method will be adopted. Recommended measures will be finalised by the steering committee. The study received full ethical approval from the Ethical Committee of the Maastricht University (ref. FHML-REC/2021/103). The study findings will be available in both peer-reviewed articles and will also be disseminated to appropriate audiences at relevant conferences.

Lay summary

Patient-derived cells cultured in the lab are simple and cost-effective methods used to study biological and dysfunctional or disease processes. These tools are frequently used in the field of reproductive medicine. However, the lack of clear recommendations and standardised methodology to guide the laboratory work of researchers can produce results that are not always reproducible and sometimes are incorrect. To remedy this situation, we define here a method to ascertain if researchers who routinely culture cells in the lab agree or disagree on the optimal laboratory techniques. This method will be used to make recommendations for future researchers working in the field of reproductive biology to reproducibly culture endometrial cells in the laboratory.

In vitro modeling of endometriosis and endometriotic microenvironment - Challenges and recent advances

Endometriosis is a chronic condition with high prevalence in reproductive age women, defined as the growth of endometrial tissue outside the uterine cavity, most commonly on the pelvic peritoneum. The ectopic endometrial lesions exist in a unique microenvironment created by the interaction of epithelial, stromal, endothelial, glandular, and immune cell components, dominated by inflammatory, angiogenic, and endocrine signals. Current research is directed at understanding the complex microenvironment of the lesions and its relationship with different endometriosis stages, phenotypes, and disease symptoms and at the development of novel diagnostic and therapeutic concepts that minimalize the undesirable side effects of current medical management. Recreating pathophysiological cellular and molecular mechanisms and identifying clinically relevant metrics to assess drug efficacy is a great challenge for the experimental disease models. This review summarizes the complete range of available in vitro experimental systems used in endometriotic studies, which reflect the multifactorial nature of the endometriotic lesion. The article discusses the simplistic in vitro models such as primary endometrial cells and endometriotic cell lines to heterogeneous 2D co-cultures, and recently more common, 3D systems based on self-organization and controlled assembly, both in microfluidic or bioprinting methodologies. Basic research models allow studying fundamental pathological mechanisms by which menstrual endometrium adheres, invades, and establishes lesions in ectopic sites. The advanced endometriosis experimental models address the critical challenges and unsolved problems and provide an approach to drug screening and medicine discovery by mimicking the complicated behaviors of the endometriotic lesion.

Role of Betaglycan in TGF-β Signaling and Wound Healing in Human Endometriotic Epithelial Cells and in Endometriosis

Endometriosis is characterized by the presence of ectopic endometrium most often in the pelvis. The transforming growth factor-beta (TGF-β) superfamily is also involved in the pathogenesis; however, betaglycan (BG, syn. TGF-β type III receptor) as an important co-receptor was not studied. We analyzed mainly BG ectodomain shedding because released soluble BG (sBG) often antagonizes TGF-β signaling. Furthermore, we studied the role of TGF-βs and BG in wound healing and evaluated the suitability of BG measurements in serum and endocervical mucus for non-invasive diagnosis of endometriosis. Evaluation of the BG shedding and signaling pathways involved as well as wound healing was performed with enzyme-linked immune assays (ELISAs), reverse transcription-quantitative polymerase chain reaction (RT-qPCR), small interfering RNA (siRNA) knockdown, and scratch assays with human endometriotic epithelial cells. TGF-β1/2 stimulation resulted in a significant dose-dependent reduction in BG shedding in endometriotic cells, which was TGF-β/activin receptor-like kinase-5 (ALK-5)/mother against decapentaplegic homolog3 (SMAD3)- but not SMAD2-dependent. Inhibition of matrix metalloproteinases (MMPs) using the pan-MMP inhibitor GM6001 and tissue inhibitor of MMPs (TIMP3) equally attenuated BG shedding, signifying the involvement of MMPs in shedding. Likewise, recombinant BG moderately reduced the secretion of TGF-β1/2 and wound healing of endometriotic cells. TGF-β1 significantly enhanced the secretion of MMP2 and MMP3 and moderately promoted wound healing. In order to evaluate the role of BG in endometriosis, serum (n = 238) and mucus samples (n = 182) were analyzed. Intriguingly, a significant reduction in the levels of sBG in endocervical mucus but not in the serum of endometriosis patients compared to controls was observed. Collectively, these observations support a novel role for BG in the pathophysiology of endometriosis.

Translational Applications of Linear and Circular Long Noncoding RNAs in Endometriosis

Endometriosis is a chronic gynecologic disease that negatively affects the quality of life of many women. Unfortunately, endometriosis does not have a cure. The current medical treatments involve hormonal manipulation with unwanted side effects and high recurrence rates after stopping the medication. Sadly, a definitive diagnosis for endometriosis requires invasive surgical procedures, with the risk of complications, additional surgeries in the future, and a high rate of recurrence. Both improved therapies and noninvasive diagnostic tests are needed. The unique molecular features of endometriosis have been studied at the coding gene level. While the molecular components of endometriosis at the small RNA level have been studied extensively, other noncoding RNAs, such as long intergenic noncoding RNAs and the more recently discovered subset of long noncoding RNAs called circular RNAs, have been studied more limitedly. This review describes the molecular formation of long noncoding and the unique circumstances of the formation of circular long noncoding RNAs, their expression and function in endometriosis, and promising preclinical studies. Continued translational research on long noncoding RNAs, including the more stable circular long noncoding RNAs, may lead to improved therapeutic and diagnostic opportunities.

Targeted inhibition of TAK1 abrogates TGFβ1 non-canonical signaling axis, NFκB/Smad7 inhibiting human endometriotic cells proliferation and inducing cell death involving autophagy

Transforming growth factor (TGFβ) is known to play a major role in establishment and maintenance of endometriosis as reported by our group earlier, the underlying mechanism remains to be explored. We deciphered the involvement of TAK1 in TGFβ1- induced cellular responses and delineated the signaling mechanism in human endometriotic cells. The endometriotic cells showed elevated expression of TGFβ1 signaling-effector molecules. TGFβ1 exposure to endometriotic cells induced the expression of the downstream target molecules indicating that TGFβ1 is implicated in the commencement ofTAK1/NFκB-p65/Smad7 cascade. The silencing of TAK1 in endometriotic cells attenuated the TGFβ1 -induced NFκB transcriptional activation and nuclear translocation of NFκB-p65 subunit. The pharmacological inhibition of NFκB by QNZ or knockdown of TAK1 reduced the expression of Smad7 and Cox2. The knockdown of TAK1 in endometriotic cells showed G1 phase cell-cycle arrest and showed low BrdU-incorporation in the presence of TGFβ1. The inhibition of TAK1 attenuated the TGFβ1 signaling activation indicating that TAK1 is a crucial mediator for TGFβ1 action in endometriotic cells. The exposure of endometriotic cells to TAK1 inhibitor, celastrol caused activation of caspase-3 and -9 that led to PARP cleavage and induced apoptosis. Simultaneously, autophagy occurred in celastrol-treated and TAK1-silenced cells as was evidenced by the formation of autophagosome and the increased expression of autophagic markers. Thus, TAK1 activation appears to protect the growth of endometriotic cells by suppressing the cell death process. Overall, our study provided the evidence that of TAK1 significant in the endometriotic cell regulation and mediates a functional cross-talk between TGFβ1 and NFκB-p65 that promotes the growth and inflammatory response in endometriotic cells.

Endometriosis and Phytoestrogens: Friends or Foes? A Systematic Review

The aim of this systematic review was to provide comprehensive and available data on the possible role of phytoestrogens (PE) for the treatment of endometriosis. We conducted an advanced, systematic search of online medical databases PubMed and Medline. Only full-length manuscripts written in English up to September 2020 were considered. A total of 60 studies were included in the systematic review. According to in vitro findings, 19 out of 22 studies reported the ability of PE in inducing anti-proliferative, anti-inflammatory and proapoptotic effects on cultured cells. Various mechanisms have been proposed to explain this in vitro action including the alteration of cell cycle proteins, the activation/inactivation of regulatory pathways, and modification of radical oxidative species levels. Thirty-eight articles on the effects of phytoestrogens on the development of endometriotic lesions in in vivo experimental animal models of endometriosis have been included. In line with in vitro findings, results also derived from animal models of endometriosis generally supported a beneficial effect of the compounds in reducing lesion growth and development. Finally, only seven studies investigated the effects of phytoestrogens intake on endometriosis in humans. The huge amount of in vitro and in vivo animal findings did not correspond to a consistent literature in the women affected. Therefore, whether the experimental findings can be translated in women is currently unknown.

Pharmaceuticals targeting signaling pathways of endometriosis as potential new medical treatment: A review

Endometriosis (EM) is defined as endometrial tissues found outside the uterus. Growth and development of endometriotic cells in ectopic sites can be promoted via multiple pathways, including MAPK/MEK/ERK, PI3K/Akt/mTOR, NF-κB, Rho/ROCK, reactive oxidative stress, tumor necrosis factor, transforming growth factor-β, Wnt/β-catenin, vascular endothelial growth factor, estrogen, and cytokines. The underlying pathophysiological mechanisms include proliferation, apoptosis, autophagy, migration, invasion, fibrosis, angiogenesis, oxidative stress, inflammation, and immune escape. Current medical treatments for EM are mainly hormonal and symptomatic, and thus the development of new, effective, and safe pharmaceuticals targeting specific molecular and signaling pathways is needed. Here, we systematically reviewed the literature focused on pharmaceuticals that specifically target the molecular and signaling pathways involved in the pathophysiology of EM. Potential drug targets, their upstream and downstream molecules with key aberrant signaling, and the regulatory mechanisms promoting the growth and development of endometriotic cells and tissues were discussed. Hormonal pharmaceuticals, including melatonin, exerts proapoptotic via regulating matrix metallopeptidase activity while nonhormonal pharmaceutical sorafenib exerts antiproliferative effect via MAPK/ERK pathway and antiangiogenesis activity via VEGF/VEGFR pathway. N-acetyl cysteine, curcumin, and ginsenoside exert antioxidant and anti-inflammatory effects via radical scavenging activity. Natural products have high efficacy with minimal side effects; for example, resveratrol and epigallocatechin gallate have multiple targets and provide synergistic efficacy to resolve the complexity of the pathophysiology of EM, showing promising efficacy in treating EM. Although new medical treatments are currently being developed, more detailed pharmacological studies and large sample size clinical trials are needed to confirm the efficacy and safety of these treatments in the near future.

Three-Dimensional Biofabrication Models of Endometriosis and the Endometriotic Microenvironment

Endometriosis occurs when endometrial-like tissue grows outside the uterine cavity, leading to pelvic pain, infertility, and increased risk of ovarian cancer. The present study describes the optimization and characterization of cellular spheroids as building blocks for Kenzan scaffold-free method biofabrication and proof-of-concept models of endometriosis and the endometriotic microenvironment. The spheroid building blocks must be of a specific diameter (~500 μm), compact, round, and smooth to withstand Kenzan biofabrication. Under optimized spheroid conditions for biofabrication, the endometriotic epithelial-like cell line, 12Z, expressed high levels of estrogen-related genes and secreted high amounts of endometriotic inflammatory factors that were independent of TNFα stimulation. Heterotypic spheroids, composed of 12Z and T-HESC, an immortalized endometrial stromal cell line, self-assembled into a biologically relevant pattern, consisting of epithelial cells on the outside of the spheroids and stromal cells in the core. 12Z spheroids were biofabricated into large three-dimensional constructs alone, with HEYA8 spheroids, or as heterotypic spheroids with T-HESC. These three-dimensional biofabricated constructs containing multiple monotypic or heterotypic spheroids represent the first scaffold-free biofabricated in vitro models of endometriosis and the endometriotic microenvironment. These efficient and innovative models will allow us to study the complex interactions of multiple cell types within a biologically relevant microenvironment.

ARID1A Mutations Promote P300-Dependent Endometrial Invasion through Super-Enhancer Hyperacetylation

Endometriosis affects 1 in 10 women and is characterized by the presence of abnormal endometrium at ectopic sites. ARID1A mutations are observed in deeply invasive forms of the disease, often correlating with malignancy. To identify epigenetic dependencies driving invasion, we use an unbiased approach to map chromatin state transitions accompanying ARID1A loss in the endometrium. We show that super-enhancers marked by high H3K27 acetylation are strongly associated with ARID1A binding. ARID1A loss leads to H3K27 hyperacetylation and increased chromatin accessibility and enhancer RNA transcription at super-enhancers, but not typical enhancers, indicating that ARID1A normally prevents super-enhancer hyperactivation. ARID1A co-localizes with P300 at super-enhancers, and genetic or pharmacological inhibition of P300 in ARID1A mutant endometrial epithelia suppresses invasion and induces anoikis through the rescue of super-enhancer hyperacetylation. Among hyperactivated super-enhancers, SERPINE1 (PAI-1) is identified as an essential target gene driving ARID1A mutant endometrial invasion. Broadly, our findings provide rationale for therapeutic strategies targeting super-enhancers in ARID1A mutant endometrium.