Surgical Induction of Endometriosis in Female Mice

Endometriotic tissue fragments are viable after cryopreservation in an ex vivo tissue model recapitulating the fibrotic microenvironment

STUDY QUESTION

Is it possible to establish an ex vivo endometriosis model using cryopreserved endometriotic tissue fragments?

SUMMARY ANSWER

Cryopreserved endometriotic tissue fragments remain viable after thawing and during at least 3 days of culture and can therefore be used to establish an ex vivo endometriosis model to efficiently test potential therapeutic agents.

WHAT IS KNOWN ALREADY

Endometriosis is the most prevalent benign gynecologic disease with an enormous societal burden; however, curative therapies are still lacking. To efficiently test potential new therapies, an ex vivo model based on previously cryopreserved endometriotic tissue that recapitulates the different endometriosis subtypes and their microenvironment is highly desirable.

STUDY DESIGN, SIZE, DURATION

Endometriotic tissue fragments of three different subtypes were obtained from 28 patients by surgical resection. After cryopreservation and thawing, viability and metabolic activity of these tissue fragments were assessed. Viability was compared with fresh fragments from 11 patients directly after surgical removal. Experimental intervention studies were performed in cryopreserved and thawed tissue fragments from two patients to confirm the usability of these tissues for ex vivo intervention studies.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Endometriotic tissue fragments (n = 45) were cryopreserved according to three different protocols. After thawing, fragments were cultured for 24 h. A resazurin-based assay was performed to assess the metabolic activity of the tissue fragments. In addition, cell type-specific viability was analyzed by VivaFix, Hoechst 33342, and α-smooth muscle actin immunofluorescence staining and confocal microscopy. The presence of endometriosis was histologically confirmed based on hematoxylin-eosin staining. Cryopreserved and thawed tissue fragments were treated for 72 h with pirfenidone or metformin and COL1A1 and CEMIP gene expressions were assessed using RT-PCR and RT-qPCR, either in the whole tissue fragments or in myofibroblasts isolated by laser capture microdissection.

MAIN RESULTS AND THE ROLE OF CHANCE

Metabolic activity of endometriotic tissue fragments obtained from peritoneal (PER), ovarian (OMA), and deep (DE) endometriotic lesions was well preserved after cryopreservation in a dimethyl sulfoxide-based medium and was comparable with fresh tissue fragments. Relative metabolic activity compared to fresh tissue was 70% (CI: 92-47%) in PER, 43% (CI: 53-15%) in OMA and 94% (CI: 186-3%) in DE lesions. In fragments from PE lesions 92% (CI: 87-96%), from OMA lesions 95% (CI: 91-98%), and from DE lesions 88% (CI: 78-98%) of cells were viable after cryopreservation and thawing followed by a 24-h culture period. Differences in gene expression of fibrotic markers COL1A1 and CEMIP after 72-h treatment with pirfenidone or metformin could be detected in whole tissue fragments and in isolated myofibroblasts, indicating that cryopreserved and thawed endometriotic tissue fragments are suitable for testing anti-fibrotic interventions.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Viability and metabolic activity of the endometriotic tissue fragments may have been partially compromised by damage sustained during the surgical procedure, contributing to inter-sample variance.

WIDER IMPLICATIONS OF THE FINDINGS

The storage of viable endometriotic tissue fragments for later usage in an ex vivo model creates the possibility to efficiently test potential new therapeutic strategies and facilitates the exchange of viable endometriotic tissue between different research laboratories.

STUDY FUNDING/COMPETING INTEREST(S)

This study was not financially supported by external funding. The authors declare no competing interest.

TRIAL REGISTRATION NUMBER

N/A.

Targeting the chemerin/CMKLR1 axis by small molecule antagonist α-NETA mitigates endometriosis progression

Endometriosis is a common gynecological disease, characterized by the presence of endometrial-like lesions outside the uterus. This debilitating disease causes chronic pelvic pain and infertility with limited therapeutics. Chemerin is a secretory protein that acts on CMKLR1 (Chemokine-Like Receptor 1) to execute functions vital for immunity, adiposity, and metabolism. Abnormal chemerin/CMKLR1 axis underlies the pathological mechanisms of certain diseases including cancer and inflammatory diseases, but its role in endometriosis remains unknown. Herein, our results showed that chemerin and CMKLR1 are up-regulated in endometriotic lesions by analyzing the human endometriosis database and murine model. Knockdown of chemerin or CMKLR1 by shRNA led to mesenchymal-epithelial transition (MET) along with compromised viability, migration, and invasion of hEM15A cells. Most importantly, 2-(α-naphthoyl) ethyltrimethylammonium iodide (α-NETA), a small molecule antagonist for CMKLR1, was evidenced to exhibit profound anti-endometriosis effects (anti-growth, anti-mesenchymal features, anti-angiogenesis, and anti-inflammation) in vitro and in vivo. Mechanistically, α-NETA exhibited a dual inhibition effect on PI3K/Akt and MAPK/ERK signaling pathways in hEM15A cells and murine endometriotic grafts. This study highlights that the chemerin/CMKLR1 signaling axis is critical for endometriosis progression, and targeting this axis by α-NETA may provide new options for therapeutic intervention.

Contribution of CD4+ cells in the emotional alterations induced by endometriosis in mice

Endometriosis is a disease defined by the presence of endometrial tissue in extrauterine locations. This chronic condition is frequently associated with pain and emotional disorders and has been related with altered immune function. However, the specific involvement of immune cells in pain and behavioral symptoms of endometriosis has not been yet elucidated. Here, we implement a mouse model of non-surgical endometriosis in which immunocompetent mice develop abdomino-pelvic hypersensitivity, cognitive deficits, anxiety and depressive-like behaviors. This behavioral phenotype correlates with expression of inflammatory markers in the brain, including the immune cell marker CD4. Depletion of CD4 + cells decreases the anxiety-like behavior of mice subjected to the endometriosis model, whereas abdomino-pelvic hypersensitivity, depressive-like behavior and cognitive deficits remain unaltered. The present data reveal the involvement of the immune response characterized by CD4 + white blood cells in the anxiety-like behavior induced by endometriosis in mice. This model, which recapitulates the symptoms of human endometriosis, may be a useful tool to study the immune mechanisms involved in pain and behavioral alterations associated to endometriosis.

Kappa opioid receptor modulation of endometriosis pain in mice

The kappa opioid receptor is a constituent of the endogenous opioid analgesia system widely expressed in somatosensory nervous pathways and also in endometrial tissues. This work investigates the possible involvement of kappa opioid receptor on the nociceptive, behavioral and histopathological manifestations of endometriosis in a murine model. Female mice receiving endometrial implants develop a persistent mechanical hypersensitivity in the pelvic area that is stronger during the estrus phase of the estrous cycle. The kappa opioid receptor agonist U50,488H produces a dose-dependent relief of this mechanical hypersensitivity, regardless of the cycle phase. Repeated exposure to a low dose of U50,488H (1 mg/kg/day s.c. for one month) provides sustained relief of mechanical hypersensitivity, without tolerance development or sedative side effects. Interestingly, this treatment also inhibits a decreased rearing behavior associated with spontaneous pain or discomfort in endometriosis mice. This KOR-mediated pain relief does not prevent the anxiety-like behavior or the cognitive impairment exhibited by endometriosis mice, and the growth of endometriotic cysts is also unaltered. These data provide evidence of strong pain-relieving properties of kappa opioid receptor stimulation in female mice with endometriosis pain. The persistence of affective and cognitive manifestations suggests that these comorbidities are independent of pelvic pain and simultaneous treatment of these comorbidities may be necessary for successful management of endometriosis.