Role of the PI3K and Hippo pathways in follicle activation after grafting of human ovarian tissue

PURPOSE

Our aim was to elucidate the mechanisms involved in follicle activation of the ovarian reserve after human ovarian tissue transplantation, with specific focus on the role of the effectors of the PI3K (mTOR and FOXO1) and Hippo (YAP) signaling pathways and whether they are somehow altered.

METHODS

Frozen-thawed ovarian tissue was collected from six women (age 25-35 years) undergoing surgery for non-ovarian pathologies and divided into 4 fragments in each case: one for non-grafted controls and three for grafting to immunodeficient mice for 3, 7 and 21 days. The tissue was processed for hematoxylin and eosin staining, immunohistochemistry and immunofluorescence at different timepoints before and after grafting. Activation of the PI3K and Hippo signaling pathways was investigated by analysis of mTOR phosphorylation, FOXO1 cytoplasmic localization and YAP nuclear localization.

RESULTS

No change in mTOR levels was observed in primordial follicles post-transplantation, but a significant upturn was recorded in growing follicles compared with primordial follicles, irrespective of grafting time. A higher percentage of primordial follicles was also found with FOXO1 in the cytoplasm after 3 days of transplantation than in non-grafted controls. Finally, a greater proportion of primordial follicles was detected with YAP in the nucleus at all timepoints after grafting.

CONCLUSIONS

This study supports the hypothesis that follicle activation may occur as an early event after transplantation, with follicle growth and death both contributing to the burnout phenomenon. This is the first time that the effectors of the PI3K and Hippo pathways have been investigated in grafted human ovarian tissue and their role in burnout documented.

Uterine fibroid management: Today and tomorrow

Current treatments for fibroids are mainly surgical and expensive, so alternatives need to be found. It is, therefore, vital to develop and evaluate alternatives to surgical procedures, especially when fertility preservation is the goal. Selective progesterone receptor modulators (SPRMs) are synthetic compounds that have either an agonistic or antagonistic impact on target tissues determined by their binding to progesterone receptors. Their mixed activity depends on recruitment of cofactors that regulate transcription along so-called genomic pathways, as well as nongenomic interactions with other signaling pathways. There is no doubt that surgery remains indicated in some instances, but we must now establish whether use of SPRMs (notably ulipristal acetate) allows less invasive surgery or even complete avoidance of surgery. Long-term intermittent administration of ulipristal acetate will undoubtedly change our approach to the management of uterine fibroids according to the International Federation of Gynecology and Obstetrics classification, which provides a comprehensive basis for different treatment options. When considering less invasive techniques (uterus-sparing options like myomectomy), the choice is guided by the size, number and location of fibroids, as well as the personal experience of the gynecologist and available equipment. There is now a growing body of evidence pointing to the crucial role of progesterone pathways in the pathophysiology of uterine fibroids. SPRMs should, therefore, be considered an alternative to surgical therapy, or at least an adjunct to surgery, as illustrated in the algorithms. © 2019 Japan Society of Obstetrics and Gynecology.

Two-step transplantation with adipose tissue-derived stem cells increases follicle survival by enhancing vascularization in xenografted frozen-thawed human ovarian tissue

STUDY QUESTION

Do adipose tissue-derived stem cells (ASCs) enhance vascularization and follicle survival in xenografted ovarian tissue using a two-step transplantation approach?

SUMMARY ANSWER

Higher rates of oxygenation and vascularization of ovarian tissue, as well as increased follicle survival rates, were detected in the early post-grafting period.

WHAT IS KNOWN ALREADY

ASCs have multilineage differentiation potential, proangiogenic properties and enhance vascularization in a peritoneal grafting site. Some studies suggest that using ASCs may improve ovarian tissue quality by enhancing graft angiogenesis.

STUDY DESIGN, SIZE, DURATION

A total of 15 severe combined immunodeficient (SCID) mice were intraperitoneally grafted with frozen-thawed human ovarian tissue (OT) from five different patients. A peritoneal transplantation site had been previously prepared in a first step using either empty fibrin (Fi+OT group [n = 5]) or ASC-loaded fibrin (Fi/ASCs+OT group [n = 5]) for 14 days prior to grafting. Five mice underwent the standard one-step transplantation procedure and served as controls (OT group). Lithium phthalocyanine (LiPc) crystals were inserted into all grafted human ovarian tissue before transplantation. Levels of partial pressure of oxygen (pO2) in grafts were monitored in vivo by electron paramagnetic resonance (EPR) oximetry on Days 3 and 7. Samples for histology and immunohistochemistry (IHC) were collected after euthanizing the mice on Day 7 following EPR. One piece of ovarian tissue per patient was fixed for analysis to serve as non-grafted controls.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Prospective experimental study conducted at the Gynecology Research Unit, Université Catholique de Louvain. All materials were used to perform pO2 measurements (EPR oximetry), histological (haematoxylin and eosin staining), immunohistochemistry (anti-mouse and human double CD34 and anti-human Ki-67) and TUNEL analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

A significant increase in pO2 was observed in all groups between Days 3 and 7 (P < 0.001). A significantly higher pO2 level was observed in the Fi/ASCs+OT group compared to the OT group on Day 7 (P = 0.028). Total CD34-positive vessel area on Day 7 was greater in the Fi/ASCs+OT group than in any other group (vs non-grafted group: P = 0.0014; vs OT group: P = 0.013; vs Fi+OT group: P = 0.018). Primordial follicle survival rates after grafting were higher in the Fi/ASCs+OT group than in the OT (P = 0.0059) or Fi+OT groups (P = 0.0307). TUNEL-positive follicle percentages after grafting were significantly lower in the Fi/ASCs+OT group than in any other grafted tissue (vs OT group: P = 0.045; vs Fi+OT group: P = 0.0268). Percentages of Ki-67-positive primordial follicles were significantly higher in all grafted groups compared to non-grafted tissue controls (P < 0.01).

LIMITATIONS REASONS FOR CAUTION

As demonstrated by our results, the proposed two-step ovarian tissue transplantation procedure using ASCs enhances vascularization in the early post-grafting period, leading to increased follicle survival rates and decreased apoptosis. However, mechanisms involved in the proangiogenic behavior of ASCs remain to be elucidated.

WIDER IMPLICATIONS OF THE FINDINGS

Our results suggest that the proposed transplantation procedure with ASCs is a promising step towards potentially solving the problem of massive follicle loss after ovarian tissue grafting.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by grants from the Fonds National de la Recherche Scientifique de Belgique (FNRS-PDR Convention T.0077.14, grant Télévie No. 7.6515.16 F to DDM and grant 5/4/150/5 awarded to MMD and CAA is research associate, FRS-FNRS), Fonds Spéciaux de Recherche, Fondation St Luc, and Foundation Against Cancer, and donations from the Ferrero family.

Fibroid management in premenopausal women

Uterine fibroids are the most common tumors affecting premenopausal women, responsible for bleeding, pain, and reduced quality of life. When symptomatic, their management mainly involves surgery, which is all too often radical (hysterectomy). While surgical options sparing the uterus (hysteroscopic and laparoscopic myomectomy) and other non-surgical approaches do indeed exist, drug-based therapies are associated with lower costs and morbidity rates. Since progesterone is required for fibroid growth, gonadotropin agonists have been used to control bleeding and decrease fibroid volume, but they only represent a temporary remedy due to adverse events. Ulipristal acetate (UPA), a selective progesterone receptor modulator, is indicated for fibroid management. It is safe, provides fast control of bleeding, and causes sustained fibroid volume reduction in the vast majority of cases (80%). Indeed, UPA-treated fibroids shrink by a combination of inhibition of cell proliferation, stimulation of cell death, and fibrosis resorption. In the case of symptom recurrence, repeated intermittent 3-month courses of daily UPA considerably maximize the impact of treatment, sometimes resulting in complete disappearance of treated fibroids. Despite the therapeutic dose of UPA being very well tolerated, patients with liver anomalies or disorders should be excluded at screening according to European Medicines Agency-Pharmacovigilance Risk Assessment Committee (PRAC) recommendations. We therefore propose new algorithms for fibroid management in premenopausal women with symptomatic fibroids, depending on their localization, the patient's wishes, and clinical response, while monitoring liver enzymes and bilirubin, as recommended by the PRAC, in order to minimize the risks of possible liver toxicity.

In vitro Activation Prior to Transplantation of Human Ovarian Tissue: Is It Truly Effective?

Research Question: What are the true benefits, if any, of disrupting the Hippo signaling pathway and stimulating the Akt pathway in xenotransplanted human ovarian tissue using an in vitro activation (IVA) approach? Design: Human ovarian tissue was retrieved from 18 young patients by laparoscopy and grafted to 54 severe combined immunodeficient mice. The experiment was conducted using fresh ovarian tissue (group I; n = 6 women), slow-frozen-thawed ovarian tissue (group II; n = 6 women), and vitrified-warmed ovarian tissue (group III; n = 6 women). Slow-freezing and vitrification procedures were performed according to Gosden's and Kawamura's protocols, respectively. The tissue (fresh, slow-frozen, and vitrified) was fragmented into small cubes (1 × 1 × 1 mm) to disrupt the Hippo signaling pathway and cultured or not in IVA medium for 48 h with Akt stimulators (PI3K stimulator and PTEN inhibitor), before being transplanted to the mice. All the grafts were maintained for 28 days. Results: (1) Follicular density: Follicular density decreased in all groups after transplantation, most significantly in the vitrification group. Culture with IVA had no impact. (2) Follicle activation: Addition of PI3K stimulator and PTEN inhibitor for 48 h prior to grafting did not significantly change the proportion of primordial follicles in any of the groups (fresh, slow-frozen, or vitrified tissue) compared to 48 h of control culture without these molecules. Particularly, vitrification and culture in IVA medium yielded no benefits in terms of growing follicle percentages or follicle proliferation rates. The large proportion of growing follicles in the vitrified tissue group after grafting may have been responsible for the higher rate of atresia. Conclusion: We were unable to demonstrate any significant benefits of cutting ovarian tissue into small cubes and applying IVA with Akt stimulators. The association of vitrification and transplantation was actually found to be the most deleterious combination with respect to the follicle reserve, and even worse when culture with Akt stimulators was performed.

Techniques for ovarian tissue transplantation and results

Fertility preservation has emerged as a field of growing interest thanks to increasingly effective cancer treatments in women. For young women with good prospects of surviving cancer, fertility preservation counseling before gonadotoxic treatment is imperative to offer them a potential chance of future childbearing. Ovarian tissue cryopreservation and transplantation emerges as a strategy for fertility preservation, especially for prepubertal girls, adolescents and women in whom cancer treatment cannot be delayed. Numerous surgical techniques have been reported and are currently being used for frozen-thawed ovarian tissue reimplantation, but successful approaches all adhere to the same fundamental micro-surgical principles: 1) finding a well vascularized orthotopic transplantation site, and 2) fixing the ovarian tissue by means of stitches, Interceed® and/or fibrin glue. Orthotopic reimplantation has proved to be the most effective technique in terms of resumption of ovarian endocrine function in more than 95% of all reported cases, and fertility restoration in over than 40% of patients in our series.

Ovarian endometriosis and fertility preservation: a challenge in 2018

Endometriosis is a benign, estrogen-dependent gynecological disorder. It is now well established that three different forms of endometriosis can occur in the pelvic cavity, namely peritoneal endometriosis, ovarian endometriosis and deep endometriotic nodules of the rectovaginal septum. Treatment of endometriosis-associated infertility has been investigated using both medical and surgical modalities. Surgery for ovarian endometriosis can lead to premature ovarian insufficiency (POI) and further infertility, so one of the most important goals of therapy should be preserving fertility. Procedures combining stripping and ablation should be considered the first-line approach for ovarian endometrioma-related infertility, in order to protect the ovarian reserve, which may already be depleted even before surgery. Autotransplantation of ovarian tissue should be considered in case of mandatory radical treatment (oophorectomy), or if conservative treatment poses a risk. For patients at risk of POI, particularly those undergoing gonadotoxic treatment, two main fertility preservation options exist: oocyte vitrification or reimplantation of fresh or frozen ovarian tissue. Both have advantages and disadvantages.

From isolation of human ovarian follicles to the artificial ovary: tips and tricks

Cryopreservation and transplantation of ovarian tissue has proved to restore both endocrine and reproductive functions in cancer patients. However, women with a high risk of ovarian involvement cannot undergo ovarian tissue transplantation due to possible recurrence of the disease. Therefore, different teams worldwide are now working on the development of experimental strategies, like the transplantable artificial ovary (TAO), with the noble goal to offer to these patients hope for future conception. This article discusses some essential points for the creation of a TAO and reviews the latest progress made.

Indications for fertility preservation in women from malignant diseases to benign conditions to age-related fertility decline

Oocyte vitrification and ovarian tissue cryopreservation are two common fertility preservation options. Oocyte vitrification provides the highest yield for women with benign diseases or those seeking fertility preservation for age-related fertility decline. This technique is also indicated for cancer women if cancer treatment can be postponed. Ovarian tissue cryopreservation has some specific indications. There is indeed no other alternative for fertility preservation in prepubertal girls, and in cancer women in whom cancer treatment cannot be postponed. This review focuses on the indications for fertility preservation from malignant diseases to benign conditions to age-related fertility decline.

Matrix Metalloproteinase Activity Correlates With Uterine Myoma Volume Reduction After Ulipristal Acetate Treatment

CONTEXT

Ulipristal acetate (UPA), a selective progesterone receptor modulator, clinically reduces uterine myoma size in 80% of cases. However, the molecular mechanism of action is still poorly understood, as is the reason why 20% of myomas do not respond to treatment.

OBJECTIVE

To elucidate whether matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are associated with myoma volume shrinkage after UPA therapy.

DESIGN

Prospective study.

SETTING

Academic research unit of a university hospital.

PATIENTS

Uterine biopsies were obtained from 59 patients with symptomatic myomas undergoing myomectomy, 45 of whom were treated preoperatively with either one or greater than or equal to two, 3-month courses of UPA and 14 not given any hormone therapy to serve as controls. Myoma volume was individually monitored during UPA therapy to determine any substantial clinical response (defined as a reduction in volume of >25%). Three groups were established based on the response to treatment: responsive (R) after one course (n = 12); R after two to four courses (n = 15); and nonresponsive (NR; n = 18).

INTERVENTIONS

UPA treatment given as preoperative management for symptomatic myomas.

MAIN OUTCOME MEASURES

MMP and TIMP expression assessed by zymography and immunohistochemistry.

RESULTS

Compared with controls and NR myomas, responders showed significantly higher expression levels for MMP-1 (P < 0.0001) and MMP-2 (P = 0.009) and significantly lower expression levels for TIMP-1 (P = 0.040).

CONCLUSIONS

The correlation found between MMP expression and volume fold change supports the notion that MMPs play a key role in UPA-induced myoma shrinkage.

Further insights into the impact of mouse follicle stage on graft outcome in an artificial ovary environment

STUDY QUESTION

Are mouse preantral follicles differently affected by isolation, encapsulation and/or grafting procedures according to stage?

SUMMARY ANSWER

Isolated secondary follicles showed superior ability to survive and grow after transplantation, which was not related to a particular effect of the isolation and/or grafting procedure, but rather to their own ability to induce neoangiogenesis.

WHAT IS KNOWN ALREADY

Isolated and encapsulated mouse preantral follicles can survive (6-27%) and grow (80-100%) in a fibrin matrix with a low concentration of fibrinogen and thrombin (F12.5/T1) after short-term transplantation.

STUDY DESIGN, SIZE, DURATION

An in vivo experimental model using 20 donor Naval Medical Research Institute (NMRI) mice (6-25 weeks of age) and 14 recipient severe combined immunodeficient (SCID) mice (11-39 weeks of age) was applied. Each NMRI mouse underwent mechanical disruption of both ovaries and isolation of primordial-primary and secondary follicles with ovarian stromal cells, in order to encapsulate them in an F12.5/T1 matrix. Twelve out of 40 fibrin clots were immediately fixed as controls (D0) (10 for histology and 2 for scanning electron microscopy [SEM]) and the others (n = 28) were grafted to the inner part of the peritoneum for 2 (16 fibrin clots) or 7 (12 fibrin clots) days (D2 and D7).

PARTICIPANTS/MATERIALS, SETTING, METHODS

This study involved the participation of the Gynecology Research Unit (Universitè Catholique de Louvain) and the Physiological Sciences Department (University of Brasília). Specific techniques were used to analyze the follicle recovery rate (hematoxylin-eosin staining), vascularization (CD34) and follicle ultrastructure (transmission electron microscopy [TEM] and SEM).

MAIN RESULTS AND THE ROLE OF CHANCE

After follicle isolation and encapsulation, a statistically higher percentage of normal follicles was observed in the secondary group (62%) than in the primordial-primary group (47%). Follicle recovery rates were 34% and 62% for primordial-primary and secondary follicles on D2, respectively, and 12% and 42% on D7, confirming that secondary follicles survive better than primordial-primary follicles after grafting. Concerning vascularization, both follicle stages exhibited similar vascularization to that seen in control mouse ovary on D7, but a significantly higher number of vessels and greater vessel surface area were detected in the secondary follicle group. Despite structural differences in fiber density between fibrin clots and ovarian tissue observed by SEM and TEM, preantral follicles appeared to be well encapsulated in the matrix, also showing a normal ultrastructure after grafting.

LARGE SCALE DATA

Not applicable.

LIMITATIONS, REASONS FOR CAUTION

As demonstrated by our results during the isolation procedure, we encapsulated a significantly higher number of round structures in the primordial-primary group than in the secondary group, which could partially explain the lower recovery rate of early-stage follicles in our previous study. However, it is not excluded that the physical and mechanical properties of the fibrin matrix may also play a role in follicle survival and growth, so further investigations are needed.

WIDER IMPLICATIONS OF THE FINDINGS

This research represents one more key step in the creation of the artificial ovary.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by grants from the Fonds National de la Recherche Scientifique de Belgique (FNRS) to C.A. Amorim as a research associate at FRS-FNRS and (grant 5/4/150/5 awarded to M.M. Dolmans), Fonds Spéciaux de Recherche, Fondation St Luc, Foundation Against Cancer, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES-Brazil) (grant #013/14 CAPES/WBI awarded to C.M. Lucci, with F. Paulini receiving a post-doctoral fellowship), and Wallonie-Bruxelles International, and donations from the Ferrero family. None of the authors have any competing interests to declare in relation to the topic.

Emerging treatment options for uterine fibroids

INTRODUCTION

Uterine fibroids (also known as leiomyomas or myomas) are the most common form of benign uterine tumors. Current management strategies involve mainly surgical interventions, but the choice of treatment is guided by patient age and desire to preserve fertility or avoid 'radical' surgery such as hysterectomy. Areas covered: There is growing evidence of the crucial role of progesterone pathways in the pathophysiology of uterine fibroids, leading to increasing use of selective progesterone receptor modulators (SPRMs) such as ulipristal acetate. We searched all published studies on medical management of fibroids with SPRMs. Expert opinion: The need for alternatives to surgical intervention is very real, especially for women seeking to preserve their fertility. These options now exist, with SPRMs proven to treat fibroid symptoms effectively. Gynecologists now have new tools in their armamentarium, opening up novel strategies for the management of uterine fibroids.

Induction of Endometriosis in Nude Mice by Transplantation of Human Peritoneal Endometriotic Tissue

Purpose

Ectopic endometrial tissue is biochemically and functionally distinct from eutopic endometrium, including differences in receptivity to steroids and invasive potential. For this reason, using ectopic endometrial tissue to induce endometriosis in animal models may be of interest to understand better the pathogenesis of this disease. The aim of this study was to evaluate the potential of human pelvic endometriotic lesions (specifically red lesions) to implant into the peritoneal cavity of nude mice.

Methods

Human peritoneal endometriotic tissue (red lesions) was injected into the pelvic cavity of nude mice. The mice were euthanized after 5 or 14 days, lesions were recovered, and histological analysis was performed. Proliferative activity and neoangiogenesis of lesions were assessed after Ki67 and CD34 immunohistological staining, respectively.

Results

After 5 and 14 days, endometriotic tissue was found to have implanted onto intact mesothelium and reorganized into structured glands and stroma, forming endometriosis-like lesions. These lesions showed considerable proliferative activity and effective neoangiogenesis.

Conclusion

This model represents a promising tool to study in vivo implantation of human ectopic endometrium, which is dissimilar to eutopic endometrium. Moreover, this study shows that glands and stroma detached from red endometriotic lesions are able to implant in other peritoneal sites, as in a metastatic process.