Progress with oocyte cryopreservation

Reproductive health in Turner's syndrome: from puberty to pregnancy

Turner syndrome (TS) is a genetic pathology that affects about 1/2500 newborn females. Turner's syndrome is characterized by highly variable genetic anomalies that consist in a partial or complete deletion of the X sexual chromosome; it can be present as a monosomy or as a mosaicism with two o three different cellular lines. 50% of the patients with Turner's syndrome has a 45 XO karyotype while the remaining cases have karyotypes with mosaicism or X isochromosome or with partial or whole Y chromosome. This pathology is characterized by multiple anomalies that involve physical and cognitive development and in particular endocrine, cardiovascular, reproductive, auditive and visual systems. Integrity of the X chromosome in essential for fertility. In TS is accelerated germ cells apoptosis. About 30% of TS girls have some pubertal development, 10-20% undergo menarche and 2-8% go through spontaneous pregnancy. Women with TS should be informed about the risk of premature menopause and should be referred, if possible, to a specialist evaluation with a doctor expert in assisted reproductive techniques. In adolescents and in adults, Premature Ovarian Insufficiency (POI) can be evaluated clinically and biochemically with the classic combination of amenorrhea and elevated FSH concentrations (hypergonadotropic hypogonadism). However, in postpubertal adolescents and adult women, reproductive hormones may remain within the normal range before POI is clinically evident, despite significant depletion of the ovarian reserve. Today, reproductive medicine offers the opportunity of fertility preservation in women with premature ovarian insufficiency (POI). Two techniques have been suggested such as ovarian cortex cryopreservation and oocytes cryopreservation.

Successful Pregnancies, Births, and Child Development Following Oocyte Cryostorage in Female Cancer Patients During 25 Years of Fertility Preservation

Simple Summary

The study goal is to demonstrate that oocyte cryopreservation is a feasible and efficient option for fertility preservation in cancer patients through the comparison of in vitro fertilization treatments in nononcological patients.

Abstract

The preservation of fertility in cancer patients is a crucial aspect of modern reproductive medicine. Amenorrhea and infertility often occur after cancer therapy, worsening the quality of life. Cryopreservation of oocytes in young cancer patients is a therapeutic option for preserving fertility. A prospective study was conducted on 508 cancer patients who underwent oocyte cryopreservation to preserve fertility between 1996 and 2021 including the COVID-19 pandemic period. Patients underwent ovarian stimulation, followed by egg retrieval, and oocytes were cryopreserved by slow freezing or vitrification. Sixty-four thawing/warming cycles were performed. Survival, fertilization, pregnancy, and birth rate over the thawing/warming cycles were obtained. The data were compared with those from a group of 1042 nononcological patients who cryopreserved supernumerary oocytes. An average of 8.8 ± 6.9 oocytes were retrieved per cycle, and 6.1 ± 4.2 oocytes were cryopreserved. With their own stored oocytes, 44 patients returned to attempt pregnancy. From a total of 194 thawed/warmed oocytes, 157 survived (80%). In total, 100 embryos were transferred in 57 transfer/cycles, and 18 pregnancies were achieved. The pregnancy rate per transfer and pregnancy rate per patient were 31% and 41%, respectively. No statistically significant differences were observed between oncological patients and nononcological patients. A total of 15 babies were born from oncological patients. Children born showed normal growth and development. One minor malformation was detected.

Microfluidic Encapsulation of Ovarian Follicles for 3D Culture

The ovarian follicle that contains one single oocyte is the fundamental functional tissue unit of mammalian ovary. Therefore, isolation and in vitro culture of ovarian follicles to obtain fertilizable oocytes are regarded as a promising strategy for women to combat infertility. In this communication, we performed a brief survey of studies on microfluidic encapsulation of ovarian follicles in core-shell hydrogel microcapsules for biomimetic 3D culture. These studies highlighted that recapitulation of the mechanical heterogeneity of the extracellular matrix in ovary is crucial for in vitro culture to develop early pre-antral follicles to the antral stage, and for the release of cumulus-oocyte complex (COC) from antral follicles in vitro. The hydrogel encapsulation-based biomimetic culture system and the microfluidic technology may be invaluable to facilitate follicle culture as a viable option for restoring women's fertility in the clinic.

Effect of Premature Menopause on Sexuality

Premature menopause, that is, menopause – spontaneous or iatrogenic – occurring at or before the age of 40 years, affects sexual identity, sexual function and sexual relationships. The woman's health, wellbeing and achievement of life's goals may be variably impaired. Factors modulating the individual's sexual outcome after premature menopause include: etiological heterogeneity of premature menopause and associated medical and sexual comorbidities; psychosexual vulnerability to premature menopause and associated infertility in survivors of childhood and adolescent cancers; impact of premature menopause on women's sexual identity, sexual function – particularly the biological basis of desire, arousal, orgasm and vaginal receptivity – and sexual relationships; partner-related factors; fertility issues; and preventive/therapeutic measures. Hormone therapy is indicated but long-term safety data are lacking. An interdisciplinary medical and psychosexual approach comprises appropriate counseling, fertility protection, when feasible, individualized hormone therapy and specific psychosexual treatment(s). Further research on fertility protection and the safety of long-term hormone therapy after premature menopause is needed.

Improved low-CPA vitrification of mouse oocytes using quartz microcapillary

Cryopreservation by low-cryoprotectant (CPA) vitrification has the potential to combine all the advantages of the conventional high-CPA vitrification and slow-freezing approaches while avoiding their drawbacks. However, current low-CPA vitrification protocol for cryopreservation of oocytes requires a lengthy and multi-step procedure for unloading CPAs. In this study, we report a much-simplified procedure of using quartz microcapillary (QMC) for low-CPA vitrification of mouse oocytes with only one step for unloading CPAs. The immediate viability of oocytes after the improved low-CPA vitrification was determined to be more than 90%. Moreover, no significant difference was observed in terms of embryonic development from the two-cell to blastocyst stages between the fresh and vitrified oocytes after in vitro fertilization (IVF). This improved low-CPA vitrification technology has the potential for efficient cryopreservation of oocytes to preserve the fertility of mammals including humans for assisted reproductive medicine, maintenance of animal resource and endangered species, and livestock management.

How developments in cryobiology, reproductive technologies and conservation genomics could shape gene banking strategies for (farm) animals

Many local breeds are currently at risk because of replacement by a limited number of specialized commercial breeds. Concurrently, for many breeds, allelic diversity within breeds declines because of inbreeding. Gene banking of germplasm may serve to secure the breeds and the alleles for any future use, for instance to recover a lost breed, to address new breeding goals, to support breeding schemes in small populations to minimize inbreeding, and for conservation genetics and genomics research. Developments in cryobiology and reproductive technology have generated several possibilities for preserving germplasm in farm animals. Furthermore, in some mammalian and bird species, gene banking of material is difficult or impossible, requiring development of new alternative methods or improvement of existing methods. Depending on the species, there are interesting possibilities or research developments in the use of epididymal spermatozoa, oocytes and embryos, ovarian and testicular tissue, primordial germ cells, and somatic cells for the conservation of genetic diversity in farm- and other animal species. Rapid developments in genomics research also provide new opportunities to optimize conservation and sampling strategies and to characterize genome-wide genetic variation. With regard to gene banks for farm animals, collaboration between European countries is being developed through a number of organizations, aimed at sharing knowledge and expertise between national programmes. It would be useful to explore further collaboration between countries, within the framework of a European gene banking strategy that should minimize costs of conservation and maximize opportunities for exploitation and sustainable use of genetic diversity.

Fertilization studies and assisted fertilization in mammals: their development and future

Studies of mammalian fertilization progressed very slowly in the beginning because of difficulties in obtaining a large quantity of fully mature eggs at one time. With progression of techniques to collect and handle eggs and spermatozoa, research in mammalian fertilization advanced rapidly. Today, far more papers are published on mammalian gametes and fertilization than those of all other animals combined. The development of assisted fertilization and related technologies revolutionized basic research as well as human reproductive medicine and animal husbandry. Reproduction is fundamental to human and animal lives. The author lists a few subjects of his personal interest for further development of basic and applied research of gametes and fertilization. Each reader will probably have more exciting subjects of future investigation.

Biotransport phenomena in freezing mammalian oocytes

Water transport across the cell plasma membrane and intracellular ice formation (IIF)-the two biophysical events that may cause cell injury during cryopreservation-were studied by cryomicroscopy and modeling using mammalian (Peromyscus) oocytes. Unusually high activation energy for water transport across the cell plasma membrane was identified indicating that the water transport process is unusually sensitive to temperature (and cooling rate). Although literally all studies on IIF were conducted using protocols with ice-seeding (seeding extracellular ice usually at ≥-7 °C), it is not used for cell cryopreservation by vitrification that is becoming increasingly popular today. In this article, we show that ice-seeding has a significant impact on IIF. With ice-seeding and cooling at 60 °C/min, IIF was observed to occur over a wide range from approximately -8 to -48 °C with a clear change of the ice nucleation mechanism (from surface- to volume-catalyzed nucleation) at approximately -43 °C. On the contrary, without ice-seeding, IIF occurred over a much narrower range from approximately -19 to -27 °C without a noticeable change of the nucleation mechanism. Moreover, the kinetics of IIF without ice-seeding was found to be strongly temperature (and cooling rate) dependent. These findings indicate the importance of quantifying the IIF kinetics in the absence of ice-seeding during cooling for development of optimal vitrification protocols of cell cryopreservation.

Pharmacological interventions for fertility preservation during chemotherapy: a systematic review and meta-analysis

The rate of chemotherapy-induced ovarian failure (CIOF) has been reported as 14-100% and is age- and agent-dependent. The role of GnRH analogs (GnRHa) and oral contraceptives (OC) in the prevention of CIOF is questionable. We performed a systematic review and a meta-analysis of studies assessing the efficacy of hormonal interventions in reducing CIOF in cancer or systemic lupus erythematosus (SLE) patients treated with chemotherapy. MEDLINE, EMBASE, and conference proceedings were searched until October 2009. From 504 potentially relevant references, 21 comparative studies were included for review and analysis. Data were collected to determine the risk ratio (RR) for amenorrhea, FSH levels, pregnancy rate, and biomarkers for ovarian reserve. Sixteen studies (SLE: 4 studies, 85 patients; malignancy: 12 studies, 596 patients) which assessed GnRHa for fertility preservation prior to chemotherapy were included in the meta-analysis. Five studies which evaluated the use of OC were systematically reviewed. Meta-analysis revealed that GnRHa are effective in reducing amenorrhea rates in all patients (RR 0.26, 95% CI 0.14-0.49). Pregnancy rate was higher in the GnRHa arm. The advantage of GnRHa was shown only in observational studies, but not in randomized controlled trials. Biomarkers for ovarian reserve were similar in both arms. Studies evaluating the efficacy of oral contraceptives in preserving ovarian function showed inconclusive results. GnRHa appears to improve menstruation resumption. Nevertheless, randomized prospective trials are less conclusive for their real value in conserving ovarian reserve and pregnancy. Large-scale prospective randomized trials are warranted to evaluate the role of GnRHa in preventing CIOF.

Current status of the approach to assisted reproduction

Assisted reproductive technologies are important tools in the clinical armamentarium used to treat both female and male infertility disorders. Pre-implantation genetic diagnosis offers couples at risk of having children with inheritable disorders the ability to analyze the genetic make-up of embryos before transfer. For patients undergoing treatment of cancer with chemotherapy or radiation therapy, these technologies offer the potential for the preservation of future fertility. As technology evolves, it is likely the clinical applications of assisted reproduction will continue to develop and expand in the future to enhance fertility.

Assessment of ovarian reserve following ovarian tissue banking and/or GnRH-a co-treatment prior to chemotherapy in patients with Hodgkin's disease

PURPOSE

To examine ovarian reserve following chemotherapy in women with Hodgkin's disease.

METHODS

The study included nine patients who underwent ovarian tissue cryopreservation (OTCP) prior to chemotherapy consisting of the ABVD regimen (Adriamycin, bleomycin, vinblastine, and dacarbazine) and co-treatment with gonadotropin-releasing hormone agonist (GnRH-a) (Group A), and 13 patients treated by the ABVD protocol only without GnRH-a (Group B). The average age was 25.2 +/- 2.7 years for the women in Group A and 31.8 +/- 6.8 years for those in Group B.

RESULTS

Six months following the end of chemotherapy, the menstrual cycle resumed in all Group A patients and in four Group B patients who had amenorrhea. Eight Group B patients had regular menses during and after chemotherapy. None of the patients suffered from ovarian failure. Two Group A patients conceived in the first year after completing chemotherapy.

CONCLUSIONS

Co-treatment with GnRH-a has little effect on ovarian protection in women with Hodgkin's disease.

Ovarian cryopreservation for fertility preservation: indications and outcomes

Female fertility preservation provides significantly different challenges to that for the male, with the only established method being cryopreservation of embryos thus necessitating the involvement of a male. Other, experimental, options include oocyte or ovarian tissue cryopreservation. The latter has been regarded as a potential method for more than a decade, but has resulted in the birth of only five babies. It is not possible to be certain how many women have had ovarian tissue cryopreserved. Oocyte cryopreservation also remains experimental, but approximately 100-fold more babies have been born through this technique over the last two decades. Ovarian tissue cryopreservation has the potential advantages of preservation of a large number of oocytes within primordial follicles, it does not require hormonal stimulation when time is short and indeed may be appropriate for the pre-pubertal. Disadvantages include the need for an invasive procedure, and the uncertain risk of ovarian contamination in haematological and other malignancies. We here review this approach in the context of our own experience of 36 women, highlighting issues of patient selection especially in the young, and uncertainties over the effects of cancer treatments on subsequent fertility. Of these 36 women, 11 have died but 5 have had spontaneous pregnancies. So far, none have requested reimplantation of their stored ovarian tissue. Ovarian cryopreservation appears to be a potentially valuable method for fertility preservation, but the indications and approaches best used remain unclear.

Oocyte cryopreservation: the birth of the first Hungarian babies from frozen oocytes

PURPOSE

To present data obtained with clinical application of oocyte cryopreservation.

METHODS

Slow freezing/rapid thawing in PBS based medium containing 1.5 M propanediol + 0.3 M sucrose.

RESULTS

A total of 127 embryos were transferred into 54 patients (1.9 embryo/cycle, 64 transfer cycles). Clinical pregnancy rate of 20% per cycle (13/64) and 24.0% per patient were achieved. Up-to-date, six patients delivered seven healthy babies; there are four ongoing pregnancies. Three abortions (23%) and one biochemical pregnancy (0.7%) was obtained. Implantation rates of 11% per transferred embryos (14/127) and 6.5% (14/215) per thawed eggs were found. In each case, normal karyotype was detected. No difference was found in the ratio of spindle positive oocytes at the polscope analyses done before and after freezing (75.8% vs. 82.5%).

CONCLUSION

Egg freezing is not a routine procedure yet, but there will certainly be a place for it in the future of assisted reproductive medicine.

[Procedures for fertility preservation in female cancer patients]

Improving survival rates and quality of life following modern combined cancer treatments have resulted a growing number of patients requesting maintenance of reproductive functions. Several methods are currently available to maintain fertility during oncotherapy. Even though most of them are still experimental and their efficacy and safety have not been determined, the future for fertility preservation in women with cancer is promising. In vitro fertilization with embryo cryopreservation offers an established method, but time to delay cancer treatment could be risky regarding the progression of several cancer types. Moreover, exposure to a high oestrogen milieu during ovarian stimulation is undesirable when patients have estrogen-sensitive malignant tumours. Cryopreservation of mature oocytes following in vitro fertilization and intracytoplasmatic sperm injection offers advantages, but it is still limited due to its low success rate. Emerging techniques of ovarian tissue cryopreservation followed by autotransplantation have been clinically explored. Novel technologies of tissue freezing and thawing promise improving results. However, only one live birth following autotransplanted frozen-thawed ovarian tissue has been established. This procedure can be offered in the future for prepubertal girls before cancer treatment to maintain future fertility. Gonadal tissue cryopreservation and transplantation should be considered experimental in humans for the present time until greater evidence regarding efficacy and safety is accrued.

Ovarian and oocyte cryopreservation

PURPOSE OF REVIEW

The present article is an update on progress in the two available techniques of oocyte and ovarian cryopreservation: slow cooling/rapid thawing and vitrification. A new line of research has opened in recent years: freezing the whole ovary with its vascular pedicle, so as to enable vascular grafts limiting ischemia-related follicle reserve loss.

RECENT FINDINGS

The technique of mature oocyte vitrification has advanced significantly, with improved oocyte physiology, increased safety, and higher clinical pregnancy rates. The number of studies on whole ovary freezing has grown, and there has been a large-mammal (sheep) live birth by orthotopic graft with vascular anastomosis of a cryopreserved ovary.

SUMMARY

Ovarian and oocyte cryopreservation is essential to conserving the fertility of young women. Results of mature oocyte freezing techniques have improved significantly over the past few years, but remain poorer than those with embryo freezing. Mature oocyte vitrification is progressing well, but requires safety validation in view of the high cryoprotectant concentrations used. Ovarian cortex fragment freezing is widely used in patients, with two live births after orthotopic graft, worldwide. The problem of rapid graft exhaustion has led to a focus on whole ovary cryopreservation which has resulted in one live birth in a ewe.

Demande de préservation de la fertilité chez la femme en cas de maladie auto-immune: possibilités et pratiques en France

Cancer is not the only disease where the question of the female fertility preservation is asked. In autoimmune diseases, alkylating agents are also used and it is now established that 20 g as a cumulative dose of cyclophosphamide is associated with premature ovarian failure in 50% of 20-year-old patients. Several strategies are discussed and offered to these patients to prevent the ovarian failure: GnRH agonist treatment, in vitro fertilization and embryos cryopreservation, oocytes cryopreservation and ovarian cortex cryopreservation. These techniques might also be associated one with the other. A survey was conducted in France in order to assess the practices realised in these diseases. Four centres were asked for these diseases, concerning 17 patients (mean age: 26.2 +/- 1.8 SEM [15-43]) and systemic lupus erythematosus was the most frequent disease (7/17). Ovarian cortex cryopreservation was realised for 6 patients. Embryos or oocytes cryopreservation was realised for 2 patients including one where ovarian cortex cryopreservation was associated. In 10 cases, considering the treatment and the patient's wish no fertility preservation was realised. Female fertility preservation in autoimmune diseases is a difficult question and a national registry, such as the one conducted by the GRECOT, can help to answer this question.

Follow-up after treatment for breast cancer in young women

The majority (80%) of breast cancers are diagnosed in women over the age of 50; only 5% will be in their 20s and 30s. These women have specific needs that include genetic counselling, psychological support, advice with regard to fertility and pregnancy issues and information on coping with treatment-related morbidity. The primary purpose of follow-up is often regarded as the early detection of recurrence as well as the detection of second primary tumours. Rather than concentrating solely on detecting cancer recurrence, clinicians need to be more susceptive to symptoms related to treatment morbidity and to the information needs of their patients. This paper outlines the specific issues listed above that need to be addressed in follow-up clinics and highlights interventions that may help improve the value of follow-up appointments and quality of life for young women with breast cancer.

Legal and ethical issues in the international transaction of donor sperm and eggs

Pertinent ethical and legal issues in the international transaction of donor sperm and eggs are discussed. Firstly, there may be legislative and ethical "contradiction" by the local health authority in permitting import of donor gametes, due to varying policies on donor reimbursement in different countries. This is particularly significant in countries where the underlying principle of gamete donation is altruistic motivation, and where reimbursement is given only for direct "out-of-pocket" expenses i.e. traveling costs. Secondly, there is a lack of clear and coherent internationally-binding legislation and regulatory guidelines overseeing the exchange of donor gametes across international borders. In particular, provisions should be made for donor traceability if gametes are sourced from abroad. Thirdly, in the case of "frozen-egg donation" from abroad, patients must rightfully be informed that current cryopreservation technology is still sub-optimal, and all studies have consistently shown that the chances of conception are always lower with "frozen-eggs" compared to freshly-retrieved eggs. Finally, regulatory safeguards should be put in place to prevent fertility clinics and medical professionals from "re-selling" imported donor gametes at a profit to the patient, since it would be thoroughly unprofessional for them to earn a profit simply through the 'brokerage' of donated human material.

Does oocyte cryopreservation have a future in Hungary?

The Committee of Human Reproduction established by the Hungarian Ministry of Health is currently working on a proposition that has the intention to ban oocyte cryopreservation in Hungary temporarily. According to the notion of the committee, oocyte cryopreservation and the utilization of frozen oocytes entail enormous risks for future generations. They argue that the safety of the method is unproven. Consequently, their standpoint maintains that cryopreservation invariably remains a grave risk factor with regards to the genetic material of the oocyte by significantly increasing the risk to the offspring. Therefore,the Committee is requesting additional animal experiments to clarify the probability of permanent lesions to the spindle and alterations to the genetic material. According to their point of view, the suspension of the method is further justified since the efficiency of the procedure has yet not reached the level required for clinical adaptation. With the proposed forthcoming step,this commentary takes the opportunity to make critical comments and clarify necessary questions.

Fresh human orthotopic ovarian cortex transplantation: long-term results

BACKGROUND

Ovarian orthotopic transplantation in patients with premature ovarian failure is reported to result in full-term pregnancies. Ischaemia and freezing/thawing are potentially injurious for tissues. This study was designed to analyse the effect of ischaemia on long-term ovarian function in humans.

METHODS

Prospective case-control study. Subjects were 12 premenopausal women undergoing hysterectomy and fresh orthotopic transplantation of the entire ovarian cortex plus a control group of five patients undergoing hysterectomy only. Follow-up lasted 2 years. Serum FSH and anti-Müllerian hormone (AMH) were recorded, and ovulatory cycles were determined by vaginal ultrasound and serum progesterone levels.

RESULTS

Follow-up showed that ovulation was restored in 11 of the 12 patients who received grafts over the duration of the study (9.3 +/- 1.73 ovulations versus 12.0 +/- 0.86 in controls, NS), and 9 of 12 patients remained ovulatory after 2 years. We identified four patterns of FSH secretion during the study, 5 of 12 (41.7%) women having the same pattern as controls. There was a trend for serum AMH levels 7 days after surgery (0.16 +/- 0.02 microg/l) to be lower than pre-surgery levels (0.38 +/- 0.09 microg/l, P = 0.07) and higher in women whose FSH patterns suggested normal ovarian function, but the results did not reach significance. After transplantation, FSH correlated more closely (r = -0.639, P = 0.02) with normal ovarian function than AMH (r = 0.465, P = 0.12).

CONCLUSIONS

Fresh orthotopic ovarian cortex transplantation is a viable procedure. It maintains normal ovarian function after 2 years in 75% of cases and preserves ovarian function against ischaemia in 41.7% of patients.