Ischemia and vasculogenesis after transplantation of frozen and vitrified human ovarian tissue onto Chick Embryo Chorioallantoic Membrane (CAM)

OBJECTIVES

The first days of post-ovarian transplantation are critical periods, as the ischemic injury can diminish the success rate. In this study, the first day's events of ovarian transplantation in two dimensions of structure and ultrastructure following slow freezing and vitrification were assessed.

STUDY DESIGN

Ovarian tissues (OTs) from 10 cancerous patients were frozen in two methods of slow freezing and vitrification. Tissues were transplanted onto the CAM and then retrieved at 5 and 10 days of culture. Nine groups were assigned as follows; I-III; fresh, 5 and 10 days culture, IV-VI; vitrification, 5 and 10 days culture, and VII-IX; slow freezing, 5 and 10 days culture. Structural and ultra-structural studies were done to assess the tissue viability and integrity following CAM transplantation. Image J software was used to measure the amounts of fibrosis and necrosis.

RESULTS

The first sign of successful transplantation was found on day 3 post-transplantation. Vitrified tissues showed higher viability and transplantation rate compared to the slow frozen group (65% vs 57.5%) (p = 0.7). Tissue fibrosis and areas didn't increase significantly after cryopreservation using two methods (p > 0.05). The areas of fibrosis and necrosis and avian vessels increased significantly after 5 and 10 days of culture (p < 0.05). Large ultra-structural follicular deformities were noticed after 10 days of CAM transplantation. Better stromal ultrastructure features can be found after vitrified tissue culture. Also, the CAM transplantation technique had negative effects on the integrity of follicles, independent of the freezing procedure.

CONCLUSION

Evaluation of early events of the ovarian post-transplantation is of amount importance, since the hypoxia during this period may accelerate follicular pool depletion, before the tissue stability. Vitrification can be considered a reliable alternative for slow freezing. CAM transplantation is a good technique for confirmation of tissue viability after warming but damaged the follicle ultrastructure in a short period.

Why Turner patients with 45, X monosomy should not be excluded from fertility preservation services

In this case report, we highlight the practical dilemma, i.e. to perform ovarian tissue cryopreservation surgery in a 45, X Turner Syndrome patient or not, by reporting on the presence of follicles in a 13-year-old female diagnosed with 45, X monosomy and an unmeasurable anti-müllerian hormone serum level. We compare our results with previous research, highlight the challenges we faced in this case and provide recommendations for daily practice. Hereby, we demonstrate that excluding certain subgroups of Turner Syndrome patients (e.g. monosomy patients, and/or girls with an anti-müllerian hormone level below 2.0 ng/l) may be premature, especially based on the current state of published research data. This practical example of a challenging dilemma in the counselling of Turner Syndrome patients for fertility preservation is of interest for clinicians involved in fertility counselling and Turner Syndrome care.

Shortening the duration between ovarian removal and cryopreservation helps preserve fertility and maintain ovarian reserve after transplantation in mice

OBJECTIVE

To evaluate the effect of storage of ovaries before cryopreservation on long-term fertility and ovarian reserve after transplantation in mice.

DESIGN

Experimental study.

SETTING

University hospital.

ANIMAL(S)

C57BL/6J and C57BL/6J-Tg (CAG-GFP) female mice.

INTERVENTION(S)

Storage and cryopreservation of mouse ovaries. Long-term fertility analysis of mice transplanted with thawed ovaries.

MAIN OUTCOME MEASURE(S)

Estrous cycles, number of live births, ovarian weight, and follicular counts of ovarian grafts.

RESULT(S)

At the first mating 3 months after ovarian transplantation, the mean number of live births was 2.6 ± 0.6 in the control group (no storage); in the storage groups, the mean number of live births was 2.9 ± 0.7 after 4 hours, 1.3 ± 0.5 after 8 hours, 0.2 ± 0.2 after 12 hours, and 0.8 ± 0.5 after 24 hours of storage; the difference from the control group was significant in the 12-hour storage group. At the second mating 6 months after ovarian transplantation, the mean number of live births was 1.8 ± 0.6 in the control group and 2.4 ± 0.6 and 0.3 ± 0.2 in the 4- and 8-hour storage groups, respectively; no live births occurred in the 12- and 24-hour storage groups. Seven months after ovarian transplantation, the numbers of primordial, primary, early secondary, and late secondary follicles were significantly lower in the 8-, 12-, and 24-hour storage groups than in the control group.

CONCLUSION(S)

In mice, shortening the storage time of ovaries before cryopreservation preserved fertility and ovarian reserve after transplantation, indicating that human ovaries might be cryopreserved immediately after harvesting or transported as quickly as possible to a cryopreservation facility to allow young patients with cancer to preserve long-term fertility and ovarian reserve.

Methods of Ovarian Tissue Cryopreservation: Is Vitrification Superior to Slow Freezing?-Ovarian Tissue Freezing Methods

After cancer treatment, female survivors often develop ovarian insufficiency or failure. Oocyte and embryo freezing are well-established fertility preservation options, but cannot be applied in pre-pubescent girls, in women with hormone-sensitive malignancies, or when gonadotoxic treatment cannot be delayed. Although ovarian tissue cryopreservation (OTC) has been used to restore fertility and endocrine function, the relative efficacy of its two major protocols, slow freezing and vitrification, remains controversial. This literature review evaluates clinical and lab-based studies published between January 2012 and June 2020 to determine whether vitrification, the optimal technique for oocyte and embryo cryopreservation, preserves ovarian tissue more effectively than slow freezing. Due to limited clinical data involving ovarian tissue vitrification, most clinical studies focus on slow freezing. Only 9 biochemical studies that directly compare the effects of slow freezing and vitrification of human ovarian tissue were noted. Most studies report no significant difference in follicular morphology and distribution between cryopreservation methods, but these findings must be interpreted in the context of high methodological variability. Discrepant findings regarding the effects of cryopreservation method on follicle viability, gene expression, and hormone production require further evaluation. Early clinical outcomes appear favorable for vitrification, but additional studies and longer term follow-up are needed to establish its efficacy. Sharing data through national or international registries would expedite this analysis. However, even if research corroborates conclusions of no clinical or biochemical difference between cryopreservation methods, the decreased costs and increased efficiency associated with vitrification make this method more accessible and cost-effective.

Fertility preservation in women for medical and social reasons: Oocytes vs ovarian tissue

Approximately 10% of cancers occur in women under 45 years of age. Chemotherapy, radiotherapy, and bone marrow transplantation cure more than 90% of cancer in women, but can result in premature ovarian insufficiency depending on follicular reserve, age, and drugs used. Some benign diseases are also indications for fertility preservation, particularly those requiring chemotherapy (like thalassemia and lupus), recurrent endometriosis, and family history of premature menopause. Social reasons also account for a large proportion of women who wish to postpone pregnancy. This article discusses the two main strategies for fertility preservation, namely oocyte vitrification and ovarian tissue cryopreservation, examining the indications and results of these options. Oocyte cryopreservation is an effective approach, but further studies are needed in cancer patients to ensure the excellent outcomes obtained in women without cancer or in egg donation programs. For prepubertal girls or cases where immediate therapy is required, cryopreservation of ovarian tissue is the only available option.

Vitrification leads to transcriptomic modifications of mice ovaries that do not affect folliculogenesis progression

Ovarian tissue cryopreservation is emerging as a promising alternative for fertility preservation of cancer survivors. To date, more than a hundred couples have successfully had babies using this procedure, although it is still considered experimental and demands further investigation. In this work, we evaluated the effects of vitrification, warming and autotransplantation procedures on the morphology and gene expression of murine ovaries. Ovaries were removed from adult female C57BL6 mice (n = 15), vitrified, warmed and autotransplanted (vitrified group), additionally, ovaries were autotransplanted without vitrification (control group, n = 15). After twenty days, grafted ovaries were harvested and used for histological and ultrastructural analysis, germinal vesicle (GV) oocyte collection, RNA sequencing, and Transmission Electron Microscopy (TEM). All classes of follicles and GV were observed in both control and vitrified/warmed transplanted ovaries, and the numbers of primordial, antral and atretic follicles were not different (p > 0.05). Using RNA-seq, we detected 16,602 vs 13,527 expressed genes in vitrified and control ovaries, respectively; and 623 significantly dysregulated genes (fold change >1.5; 332 up-regulated and 291 down-regulated). Cellular membranes, cytoskeletons, and extracellular matrices were found as the main functions of the differentially expressed genes. Moreover, vitrified samples also presented ultrastructural alterations in the cytoskeleton, cell junctions, and endoplasmic reticulum. Taken together, this work showed for the first time that ovarian cells might trigger a compensatory gene regulation mechanism to maintain cellular structure and folliculogenesis progression after vitrification and autotransplantation.

Cryostorage and retransplantation of ovarian tissue as an infertility treatment

While still considered an experimental procedure in most countries, ovarian tissue cryopreservation and transplantation has been increasingly applied worldwide to restore fertility in patients with malignant and non-malignant pathologies with risk of premature ovarian insufficiency. It has yielded more than 130 live births up to now and almost all transplanted patients recovered their ovarian function. This study summarizes ovarian tissue cryopreservation and transplantation indications, procedures, their efficacy and main results and proposes different strategies to improve this strategy. Although the main focus of this study is on ovarian tissue cryopreservation and transplantation as a strategy to restore fertility, we believe that it is also important to discuss other applications for this approach.

Fertility preservation in adolescent and young adult cancer patients: From a part of a national survey on oncofertility in Japan

PURPOSE

This study evaluated the current status of reproductive disorders and provision of information on oncofertility to female adolescent and young adult (AYA) cancer patients in Japan.

METHODS

A national survey of AYA cancer survivors was conducted. Children were <15 years old, and AYAs were 15-39 years old. Results from the survivors of other than gynecological disease who underwent chemotherapy were analyzed.

RESULTS

Among the survivors, 41.4% were concerned about their reproductive function and infertility, and 36.2% were aware of menstrual cycle abnormalities. Among them, 15.5% (n = 20) of all and 21.2% (n = 17) of the AYA-onset survivors suffered infertility due to chemo- or radiotherapy and gave up childbearing. These rates were significantly higher than those of healthy AYAs. Although 80.8% of AYA-onset survivors answered that they had received information on reproductive function and infertility, only 55.8% had received information on fertility preservation methods. Furthermore, only 22.4% of all and 42.3% of AYA-onset survivors had received pretreatment information on fertility preservation methods.

CONCLUSIONS

Not a few AYA cancer survivors reported reproductive dysfunction. These findings indicate that information provided on therapy-related problems before cancer treatment in Japan was insufficient and highlight the need to improve patient decision-making and support systems for fertility preservation.

Chinese Society of Gynecological Endocrinology affiliated to the International Society of Gynecological Endocrinology Guideline for Ovarian Tissue Cryopreservation and Transplantation

In order to promote the standard application of ovarian tissue cryopreservation in China, and to provide effective scientific medical services of fertility preservation for patients, the First Chinese Guideline of Ovarian Tissue Cryopreservation and Transplantation is established according to the agreements between gynecologists, embryologists, oncologists, pediatricians, breast oncologists, hematologists, and experts on Traditional Chinese Medicine (TCM), based on already successful treated cases within Beijing Obstetrics and Gynecology Hospital, Capital Medical University, China, and based on already existing international guidelines on fertility preservation including important publications in this field. The guideline includes selection criteria, evaluation, and indications; SOPs of ovarian tissue removal, transportation, preparation, freezing, and thawing; approaches of ovarian tissue transplantation and follow-up; practical recommendations for ovarian tissue cryopreservation and transplantation including recommendations of the diseases where this method could be available, and treatment of menopausal symptoms during the peri-transplantation period (time between cryopreservation and retransplantation). The aim of this guideline was to be scientific, practical, and operable.

Fertility preservation for adolescent and young adult cancer patients in Japan

Adolescent and young adult (AYA) patients are generally defined as being from 15 to 39 years old. For preservation of fertility in AYA cancer patients, the best-known guideline in this field was released by the American Society of Clinical Oncology (ASCO) in 2006. However, the ASCO guideline is not necessarily applicable to Japanese cancer patients. The Japan Society for Fertility Preservation (JSFP) was formed in 2012, and a system and guideline for fertility preservation in Japanese AYA cancer patients plus children was released in July 2017. According to this guideline, patients should receive psychological and social support from health care providers such as doctors, nurses, psychologists, pharmacists, and social workers. In 2013, the American Society for Reproductive Medicine stated that freezing oocytes is a method that has passed beyond the research stage. However, freezing ovarian tissue is still a research procedure. While slow freezing of ovarian tissue is generally performed, rapid freezing (vitrification) is more popular in Japan. We have developed a new closed technique for ovarian tissue cryopreservation. It has been suggested that optical coherence tomography might be applied clinically to measure the true ovarian reserve and localize follicles in patients undergoing ovarian tissue transplantation. Combining gonadotropin-releasing hormone agonist therapy with anticancer agents might be useful for ovarian protection and it is expected that discussion of such combined treatment will continue in the future. This article outlines practical methods of fertility preservation using assisted reproductive techniques for AYA cancer patients in Japan.

Effect of mouse ovarian tissue cryopreservation by vitrification with Rapid-i closed system

PURPOSE

Currently, open systems are mainly used for cryopreservation of ovarian tissue, oocytes, and embryos, but there is a potential risk of contamination. This study was performed to assess ovarian tissue cryopreservation by a closed vitrification system (Rapid-i vitrification system™), which is already used clinically for oocyte/embryo cryopreservation.

METHODS

Ovaries of C57BL/6J mice were frozen and thawed by using the Rapid-i vitrification system™ (Rapid-i) followed by implantation into recipient mice. Hematoxylin-eosin staining was performed for histological examination of the frozen-thawed ovaries to assess follicle grade. Fertility after implantation of the ovaries was assessed from the live birth rate and the number of live pups.

RESULTS

There was no significant difference in grade 1 primary follicles between fresh ovaries (control group, 94.2 ± 2.9%) and frozen-thawed ovaries (Rapid-i group, 87.1 ± 1.8%). However, there was a significant decrease in grade 1 early and late secondary follicles in the Rapid-i group compared with the control group. The live-birth rate was significantly lower in the Rapid-i group compared with the control group (29.2 vs. 83.3%, p < 0.05). On the other hand, there was no significant difference in the average number of live pups between the control group and the Rapid-i group (3 ± 0.4 vs. 2.7 ± 0.3).

CONCLUSIONS

The Rapid-i seems to be effective for cryopreservation of mouse ovarian tissue. Under appropriate conditions, the Rapid-i could be employed for ovarian tissue cryopreservation and preservation of fertility in humans.

Morphological and Molecular Aspects of In Vitro Culture of Preantral Follicles Derived from Vitrified Ovarian

Objective

This study aimed to evaluate the expression of the genes related to folliculo-genesis after vitrification of mouse ovarian tissues using a two-step in vitro culture.

Materials and Methods

In this experimental study, vitrified and non-vitrified ovaries from 7- day old (neonate) female mice were cultured using alpha-Minimum Essential Medium (α-MEM) supplemented with 5% fetal bovine serum (FBS) for 7 days. Morphology, surface area of ovaries and percentage of normal follicles were evaluated and compared in both groups. After one-week culture, in non-vitrified group, preantral follicles of cultured ovaries were isolated and cultured in a three-dimensional alginate culture system for 12 days. Then, the collected metaphase (M) II oocytes were inseminated with capacitated spermatozoa derived from 7-8-week old (adult) male NMRI mice. Follicular diameter, oocyte maturation, fertilization, embryo development and the expression of genes related to follicular development (Pcna, Fshr and Cyp17a1,) using real time reverse transcription-polymerase chain reaction (RT-PCR) were assessed at the end of last culture period in both groups.

Results

The ovarian area in vitrified group (162468.20 703.78) was less than non-vitrified group (297211.40 6671.71), while the percentage of preantral follicles in vitrified group (18.40%) was significantly lower than those of non-vitrified group (24.50%) on day 7 of culture (P<0.05). There were no significant differences between the two groups in terms of follicular diameter, expression of genes related to development of follicles, oocyte maturation, fertilization, as well as embryo development (P>0.05).

Conclusion

The results of this study showed that vitrification of ovarian tissue following in vitro culture had negative impact on the survival and development of follicles within the tissue. However, no significant alterations were observed in development, gene expression and hormonal production of in vitro culture of isolated follicles derived from vitrified ovarian tissues as compared to the non-vitrified samples.

Accuracy and safety verification of ovarian reserve assessment technique for ovarian tissue transplantation using optical coherence tomography in mice ovary

Except for histological study, there are currently no suitable techniques available for the detection and identification of primordial follicles in ovary of primary ovarian insufficiency patients who have undetectable AMH levels. Also, the ability to locate and quantify follicles on ovarian cortex strips, without fixation, is valuable for patients who could undergo subsequent successful ovarian tissue transplantation. Although optical coherence tomography (OCT) is a well-established high resolution imaging technique without fixation commonly applied in biomedicine, few reports are available on ovarian tissue imaging. In present study, we established standard OCT follicle images at each developmental stage, including the primordial follicle, and demonstrated the efficacy of OCT to estimate IVF outcome in transplanted mice ovary like ovarian reserve tests. Unfortunately, the current commercial OCT could not be used to accurate follicle count the number of follicles for whole ovary, because the maximum depth of examination was 100 μm. And we demonstrated the safety of OCT examination, it did not affect IVF outcome and birth defect rate, and reproductive ability. Although there is room for improvement, these findings will be first step to bring OCT examination a step closer to clinical application for measuring true ovarian reserve and localizing follicles.