Ovarian tissue cryostorage and grafting: an option to preserve fertility in pediatric patients with malignancies

Ethical, legal, social, and policy issues of ovarian tissue cryopreservation in prepubertal girls: a critical interpretive review

PURPOSE

Despite the increasing number of childhood cancer survivors, significant advances in ovarian tissue cryopreservation (OTC) technique and medical societies' recommendations, fertility preservation (FP) and FP discussions are not always offered as a standard of care in the pediatric context. The aim of this literature review is to understand what ethical, legal, social, and policy issues may influence the provision of FP by OTC in prepubertal girls with cancer.

METHODS

A critical interpretive review of peer-reviewed papers published between 2000 and January 2023 was conducted, guided by the McDougall's version of the critical interpretive synthesis (Dixon-Woods), to capture recurring concepts, principles, and arguments regarding FP by OTC for prepubertal girls.

RESULTS

Of 931 potentially relevant papers, 162 were included in our analysis. Data were grouped into seven thematic categories: (1) risks of the procedure, (2) unique decision-making issues in pediatric oncofertility, (3) counseling, (4) cultural and cost issues, and (5) disposition of cryopreserved reproductive tissue.

CONCLUSION

This first literature review focusing on ethical, legal, social, and policy issues surrounding OTC in prepubertal girls highlights concerns in the oncofertility debate. Although OTC is no longer experimental as of December 2019, these issues could limit its availability and the child's future reproductive autonomy. This review concludes that specific actions must be provided to enable the offer of FP, such as supporting families' decision-making in this unique and complex context, and providing pediatric patients universal and full access to free or highly subsidized OTC.

Evaluating the safety and efficacy of cryopreserved ovarian tissue transplantation in leukemia patients with different bone marrow remission status using xenotransplantation

Background

Leukemia patients undergoing cryopreserved ovarian tissue transplantation (OTT) may carry a high risk of disease induction. Measurable residual disease (MRD) in bone marrow is linked to an elevated risk of relapse. It is controversial whether leukemia patients must be allowed to achieve measurable residual disease negative (MRD-negative) status instead of measurable residual disease positive (MRD-positive) status before ovarian tissue cryopreservation (OTC).

Objective

To explore the safety and efficacy of OTT in acute leukemia patients with different MRD status by using xenotransplantation.

Method

Cryopreserved ovarian tissue from 19 leukemia patients was thawed and xenotransplanted to ovariectomized BALB/C nude mice (n=36). The mice were divided into 2 groups based on the patient's MRD status before OTC: MRD-negative group (n=18) and MRD-positive group (n=18), additionally, a control group consisted of ovariectomized mice (n=9). Body weight was measured weekly and mortality, emaciation, and other abnormalities were recorded. Twenty-six weeks post-surgery, livers, spleens, uteruses, and ovarian grafts were removed for macroscopic and histological examinations to evaluate the efficacy of xenotransplantation and assess malignant cell contamination in mice.

Results

Follicle growth was visible in the ovarian grafts of the MRD-negative and MRD-positive groups. Compared with the ovariectomized group, a significant decrease in body weight (p<0.01) was noted, the uterine volume was notably larger, estradiol (E2) levels were significantly higher (p<0.01), and follicle-stimulating hormone (FSH) levels were significantly lower (p<0.001) in the other two groups. Mice in the MRD-positive group showed a significantly higher incidence of death (p<0.001) and emaciation (p<0.01), compared to the MRD-negative group. Histological observation revealed the presence of malignant cells in the grafts, livers, and spleens of 3 mice in the MRD-positive group. No abnormalities were observed in the mice from the MRD-negative group in both macroscopic and histological observations except one mouse was sacrificed for ascites unrelated to leukemia relapse.

Conclusion

For leukemia patients having ovarian tissue preserved in the first and only centralized human ovarian tissue cryobank in China, immunodeficient mice xenotransplantation can be a method to evaluate the safety and efficacy of OTT; the risk of malignant cell reimplantation due to OTT is higher in leukemia patients with MRD-positive status than those with MRD-negative status before OTC.

Whole-ovary decellularization generates an effective 3D bioscaffold for ovarian bioengineering

PURPOSE

To develop a new protocol for whole-ovary decellularization for the production of a 3D bioscaffold suitable for in vitro/ex vivo studies and for the reconstruction of a bioengineered ovary.

METHODS

Porcine ovaries were subjected to the decellularization process (DECELL; n = 20) that involved a freeze-thaw cycle, followed by sequential incubations in 0.5% SDS for 3 h, 1% Triton X-100 for 9 h, and 2% deoxycholate for 12 h. Untreated ovaries were used as a control (CTR; n = 6). Both groups were analyzed to evaluate cell and DNA removal as well as ECM preservation. DECELL bioscaffolds were assessed for cytotoxicity and cell homing ability.

RESULTS

DECELL ovaries maintained shape and homogeneity without any deformation, while their color turned from red to white. Histological staining and DNA quantification confirmed a decrease of 98.11% in DNA content, compared with the native tissue (CTR). Histochemical assessments demonstrated the preservation of intact ECM microarchitecture after the decellularization process. This was also confirmed by quantitative analysis of collagen, elastin, and GAG contents. DECELL bioscaffold showed no cytotoxic effects in co-culture and, when re-seeded with homologous fibroblasts, encouraged a rapid cell adhesion and migration, with repopulating cells increasing in number and aggregating in cluster-like structures, consistent with its ability to sustain cell adherence, proliferation, and differentiation.

CONCLUSION

The protocol described allows for the generation of a 3D bioscaffold that may constitute a suitable model for ex vivo culture of ovarian cells and follicles, as well as a promising tool for the reconstruction of a bioengineered ovary.

Fertility Preservation for Prepubertal Girls: Update and Current Challenges

With increasing rates of diagnosis of childhood cancers and the evolution of more effective treatment options resulting in prolonged life spans, fertility preservation counseling is an integral component of the discussion at the time of diagnosis of childhood cancers. The primary fertility preservation option that exists for prepubertal girls is ovarian tissue cryopreservation. Although ovarian tissue cryopreservation is still considered to be experimental in nature, live births have resulted from orthotopic tissue transplantation. Fertility preservation should be offered to all prepubertal girls at high-risk for premature ovarian failure as a result of gonadotoxic treatment. Ethical and legal questions surrounding these issues must be considered as more and more pediatric patients pursue fertility preservation.

Fertility preservation for women with malignant diseases: ethical aspects and risks

As cancer treatment becomes more and more effective, there is greater life expectancy for cancer patients. Because of this, depending upon the modality used in the treatment of cancer, the matter of infertility emerges before us as an issue of increasing significance. Sperm cryopreservation and embryo cryopreservation are well-established methods of fertility preservation (FP). Besides these validated FP options, some FP techniques such as oocyte cryopreservation and ovarian tissue cryopreservation are as yet in the experimental stage. FP medicine has experienced some rapid developments in recent years. The advances in this branch of medicine, however, have also brought about new ethical, medical and legal issues. Some of these include problems with obtaining the informed consent of minors, issues that arise because of the experimental nature of some methods, financial problems and the accessibility of FP methods, and the question of what happens to gametes when a patient dies. This review seeks to discuss, in the light of current literature, some ethical and technical issues and risks related to the implementation of FP methods in women with cancer.

Fertility-preserving treatment options in patients with malignant hematological diseases

The number of patients of reproductive age diagnosed with various malignant hematological diseases increases every year. These patients undergo chemotherapy, radiotherapy, and various other treatments that may have gonadotoxic effects. The life expectancy of these patients is increasing rapidly due to the variety of treatment options. As such, an increasing number of patients-as well as their parents and spouses-express their concerns about the patient's fertility post treatment. In the present review it was aimed to provide an overview of current fertility-preserving treatment options and the future of fertility preservation.

Ovarian tissue and follicle transplantation as an option for fertility preservation

OBJECTIVE

To review and summarize data from the scientific literature on ovarian tissue and follicle transplantation as an option for fertility preservation.

DESIGN

Review of pertinent literature.

SETTING

University hospital.

PATIENT(S)

Women having undergone ovarian tissue transplantation.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Review of the literature.

RESULT(S)

Over the last decade, the field of ovarian transplantation and cryopreservation has significantly progressed, becoming applicable in humans. Indeed, fresh and frozen cortical ovarian tissue transplantations have been successfully reported worldwide, resulting in around 28 healthy babies. Although ovarian-tissue harvesting seems to be safe, the risk of reimplantation of cancer from ovarian cortical transplants cannot be estimated at this time. As a consequence, auto-transplantation of ovarian tissue in women having suffered from systemic hematological malignancies is not recommended. In these situations, reimplantation of isolated ovarian follicles might represent an interesting option in the future.

CONCLUSION(S)

Although the clinical experience is limited, the robust results obtained open new perspectives for the management of premature ovarian failure resulting or not from gonadotoxic treatments.

Vitrification of in vitro matured oocytes collected from antral follicles at the time of ovarian tissue cryopreservation

BACKGROUND

In the past few years, cryopreservation of ovarian tissue has become an established procedure proposed in many centers around the world and transplantation has successfully resulted in full-term pregnancies and deliveries in human. This prospective study aims to evaluate the feasibility of vitrifying in vitro matured oocytes (IVM) isolated at the time of ovarian tissue cryopreservation to improve the efficiency of fertility preservation programs.

METHODS

Oocyte-cumulus complexes were retrieved from freshly collected ovarian cortex by aspirating antral follicular fluid, and were matured in vitro for 24-48 h prior to vitrification. Oocytes were matured in an IVM commercial medium (Copper Surgical, USA) supplemented with 75 mIU/ml FSH and 75 mIU/ml LH and vitrified using a commercial vitrification kit (Irvine Scientific, California) in high security vitrification straws (CryoBioSystem, France). Oocyte collection and IVM rates were evaluated according to the age, the cycle period and the amount of tissue collected.

RESULTS

Immature oocyte retrieval from ovarian tissue was carried out in 57 patients between 8 and 35 years of age, undergoing ovarian tissue cryopreservation. A total of 266 oocytes were isolated, 28 of them were degenerated, 200 were at germinal vesicle stage (GV), 35 were in metaphase I (MI) and 3 displayed a visible polar body (MII). The number of oocytes collected was positively correlated with the amount of tissue cryopreserved (p < 0.001) and negatively correlated with the age of the patients (p = 0.005). Oocytes were obtained regardless of menstrual cycle period or contraception. A total maturation rate of 31% was achieved, leading to the vitrification of at least one mature oocyte for half of the cohort.

CONCLUSIONS

The study showed that a significant number of immature oocytes can be collected from excised ovarian tissue whatever the menstrual cycle phases and the age of the patients, even for prepubertal girls.

Ethical issues regarding fertility preservation in adolescents and children

Certain forms of treatment for cancer in children and adolescents may significantly affect their fertility. Oncologists and specialists in reproductive medicine are attempting to use various methods of fertility preservation to address this problem. However, major medical/biological issues must be resolved before many of these methods can be considered accepted medical treatments. In addition, ethical considerations that such treatments bring to the fore, including those relevant to assent by children and the provision of experimental treatment to children, must be taken into account. This article addresses the current and future medical and ethical status of the development of fertility-preserving treatment for adolescents and children who are to receive cancer treatment.

Orthotopic and heterotopic ovarian tissue transplantation

BACKGROUND

Transplantation of ovarian tissue is, at present, the only clinical option available to restore fertility using cryopreserved ovarian tissue. More than 30 transplantations of cryopreserved tissue have been reported, and six babies have been born, worldwide, following this procedure. Despite these encouraging results, it is essential to optimize the procedure by improving the follicular survival, confirming safety and developing alternatives. Here, we review the different factors affecting follicular survival and growth after grafting.

METHODS

Relevant studies were identified by searching Pubmed up to January 2009 with English language limitation. The following key words were used: (ovarian tissue or whole ovary) AND (transplantation) AND (cryopreservation or pregnancy). Using the literature and personal experience, we examined relevant data on the different exogenous and clinical factors affecting follicular development after grafting.

RESULTS

Clinical factors such as the patient's age and the transplantation sites influenced the lifespan of the graft. A heterotopic transplantation site is not optimal but offers some advantages and it may also promote the hormonal environment after a combined heterotopic and orthotopic transplantation. Exogenous factors such as antioxidants, growth factors or hormones were tested to improve follicular survival; however, their efficiency regarding further follicular development and fertility potential remains to be established.

CONCLUSION

Additional evidence is required to define optimal conditions for ovarian tissue transplantation. Alternatives such as whole ovary or isolated follicles transplantations require further investigation but are likely to be successful in humans in the future.

Combining ovarian tissue cryobanking with retrieval of immature oocytes followed by in vitro maturation and vitrification: an additional strategy of fertility preservation

OBJECTIVE

To report an additional strategy of fertility preservation, which combines ovarian tissue cryobanking with retrieval of immature oocytes from excised ovarian tissue, followed by in vitro maturation (IVM) and vitrification.

DESIGN

Retrospective analysis of case series.

SETTING

University teaching hospital.

PATIENT(S)

Women who underwent oophorectomy or ovarian wedge resection before receiving chemotherapy and/or radiotherapy.

INTERVENTION(S)

Immature oocyte retrieval, IVM, oocyte vitrification, ovarian tissue cryobanking.

MAIN OUTCOME MEASURE(S)

Oocytes retrieved from the excised ovarian tissue, oocyte maturation rate, and number of oocytes cryopreserved by vitrification.

RESULT(S)

Four consecutive patients underwent retrieval of immature oocytes from the antral follicles of the excised ovarian tissue. The mean number of immature oocytes recovered was three (1, 3, 4, and 3, respectively). The mean maturation rate following IVM was 79% (100%, 100%, 50%, and 67%, respectively). In total, eight mature oocytes were vitrified.

CONCLUSION(S)

Oocytes can be retrieved from excised ovarian tissue, matured in vitro, and cryopreserved by vitrification. This fertility preservation technique could be combined with ovarian tissue cryobanking.

Fertility preservation: successful transplantation of cryopreserved ovarian tissue in a young patient previously treated for Hodgkin's disease

Cryopreservation of ovarian tissue is now offered as an experimental procedure to preserve the fertility of young patients with a high risk for premature ovarian failure resulting from cancer therapy. This is the only available option to preserve the fertility of prepubertal patients treated with gonadotoxic chemotherapy. At present, thousands of patients all over the world have undergone this procedure with the hope of later restoring their fertility. Although the efficiency of the transplantation of cryopreserved ovarian tissue to restore ovarian function has been established, reports of pregnancy are still very scarce. Here, we describe the second published full-term spontaneous pregnancy after an orthotopic and heterotopic transplantation of cryopreserved ovarian tissue in a 31-year-old woman previously treated by conditioning therapy for bone marrow transplantation for Hodgkin's disease. This birth gives compelling evidence for the graft origin of the gamete and confirms the efficacy of ovarian tissue transplantation in restoring human natural fertility after oncological treatment. This case report stresses the importance of proposing the ovarian tissue cryopreservation procedure to all young patients who require potentially sterilizing treatment, with all alternative options to preserve fertility being duly taken into consideration.

Preservation of female fertility during cancer treatment

Improvements in the success of cancer treatments have resulted in increased awareness of the long-term effects of treatment, of which gonadal failure is the most significant. Thus, preservation of fertility potential has become a major goal and could be realized by preventing ovarian toxicity or by cryopreservation of reproductive cells/tissues. This review aimed to critically discuss the current protocols for the management of chemotherapy-inducced/radiotherapy-induced premature ovarian failure (POF). A medical approach using the gonadotropin-releasing hormone analog (GnRHa) may act to protect the gonads during radiation and/or chemotherapy by preferentially steering cells into cell cycle arrest with a decline in responsibility to the chemotherapeutic agents. Ovarian protection by GnRHa cotreatment against chemotherapy can enable the preservation of future fertility in survivors and prevent the bone demineralization and osteoporosis associated with hypestrogenism and POF. In vitro fertilization of retrieved oocytes could enable embryo freezing in some patients. Embryo cryopreservation is considered standard practice and widely available, but may seldom be used because of a lack of a male partner, the need to postpone cancer therapy for a few weeks and the possibility that an estrogen rise may be undesirable in sensitive cancer patients. Improvement in oocyte cryopreservation may offer additional possibilities; the prolonged culture of primordial and primary follicles in vitro is still unfeasible. Currently, the cryopreservation of ovarian cortex, which hosts thousands of immature follicles, is an investigational method, but has the advantage of requiring neither a sperm donor nor ovarian stimulation. Fertility preservation is often possible in women undergoing cancer treatment. To preserve the full range of options, fertility preservation procedures should be considered as early as possible during therapy planning. (Reprod Med Biol 2008; 7: 17-27).