Ovarian tissue cryopreservation and transplantation: scientific implications

Single-cell analysis comparing early-stage oocytes from fresh and slow-frozen/thawed human ovarian cortex reveals minimal impact of cryopreservation on the oocyte transcriptome

STUDY QUESTION

Does the slow-freezing and thawing process have a negative impact on the transcriptome of oocytes isolated from early-stage human follicles compared to fresh controls?

SUMMARY ANSWER

The transcriptional profiles of fresh and frozen/thawed oocytes did not cluster separately, indicating undetectable differences between the two groups when compared to within-donor heterogeneity.

WHAT IS KNOWN ALREADY

Previous studies using histological analysis of follicle morphology, density, and stage distribution in slow-frozen/thawed human ovarian cortex compared to fresh controls showed no differences between the two groups. Clinical cases reported in the past 10 years have demonstrated that transplanted slow-frozen/thawed and fresh ovarian cortex restored normal serum FSH levels and regular menstrual cycles by 5 months. However, the slow-frozen and thawed tissue resulted in lower rates of pregnancies and live births, albeit not statistically significant.

STUDY DESIGN, SIZE, DURATION

We utilized single-cell RNA-sequencing (scRNAseq) of 144 human oocytes isolated from cadaver ovaries obtained from three donors.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Human ovarian cortex from three healthy premenopausal donors 16, 18, and 27 years old was cut into squares measuring 10 × 10 × 1 mm3 and either slow-frozen and thawed or processed fresh. First, using a novel method for isolating live oocytes from primordial and primary follicles, the ovarian cortex squares were fragmented with a McIlwain tissue chopper and enzymatically digested. Next, oocytes were mechanically denuded under a dissection microscope and placed individually into wells containing lysis buffer for scRNAseq. Lysed single oocytes were subjected to library prep using the seqWell PlexWell rapid single-cell RNA protocol. Pooled libraries were subjected to 150-bp paired-end sequencing on the NovaSeq6000 Illumina platform. In total, we sequenced 144 oocytes-24 oocytes isolated fresh and 24 oocytes isolated after slow-freezing and thawing from each of the three donors. Additionally, we performed histological analysis of fresh and frozen/thawed ovarian cortex tissue from all three donors using hematoxylin and eosin staining and analyzed morphology, follicle density, and follicle stage distribution differences between fresh and cryopreserved ovarian cortex.

MAIN RESULTS AND THE ROLE OF CHANCE

The histological analysis revealed no differences in follicle stage distribution or follicle morphology between conditions, with the percentage of normal follicles in fresh and frozen/thawed tissue, respectively, as 86.7% and 91.0% for Donor 1, 91.7% and 92.5% for Donor 2, and 96.1% and 91.1% for Donor 3. The follicle density per mm3 in fresh and frozen/thawed tissue, respectively, was 279.4 and 235.8 for Donor 1, 662.2 and 553.5 for Donor 2, and 55.8 and 71.4 for Donor 3. The difference in follicle density was not statistically significant between fresh and frozen/thawed conditions for Donors 2 and 3, and significant (P = 0.017) for Donor 1. The stromal cell densities in fresh and frozen/thawed tissue, respectively, were 0.014 in both conditions for Donor 1, 0.014 and 0.016 for Donor 2, and 0.013 and 0.014 for Donor 3. There was no statistically significant difference in stromal cell density between conditions in Donor 1 and Donor 3, though it was statistically significant (P ≤ 0.001) for Donor 2. The transcriptional profiles of fresh and frozen/thawed oocytes did not cluster separately, suggesting insignificant differences between the two groups. However, at the group mean level, there was a small shift between the fresh and frozen/thawed oocytes and the shifts were parallel across the three donors. In this comparison, fresh oocytes were enriched for gene ontology terms related to chromosome segregation and mitosis, whereas frozen/thawed oocytes were enriched for terms related to wound response, cAMP signaling, and extracellular matrix organization.

LARGE SCALE DATA

Datasets available on Zenodo.org. DOI: https://zenodo.org/records/13224872.

LIMITATIONS, REASONS FOR CAUTION

In this study, we only sequenced the oocytes isolated from early-stage follicles due to technical challenges collecting and sequencing the somatic cells surrounding the oocytes. Investigating the transcriptomic changes after freezing and thawing in the somatic cells would need to be studied in the future. Additionally, we built RNAseq libraries immediately after thawing focusing on the immediate changes. Investigation of the effects that manifest at later timepoints, either in culture or upon implantation in an animal model, may reveal additional effects of the freeze/thaw process on the transcriptome.

WIDER IMPLICATIONS OF THE FINDINGS

The only clinically approved method of fertility preservation for prepubertal cancer patients and adult patients who cannot delay cancer treatment is ovarian tissue cryopreservation. Investigation of cryopreservation-induced changes in follicles at all stages is critical to further our understanding of the safety and efficacy of using these tissues for fertility preservation in the clinic. Our study is the first to analyze transcriptomic changes between individual fresh and slow-frozen/thawed human oocytes collected from early-stage follicles. To accomplish this, we developed a novel method for dissociating both fresh and frozen/thawed human ovarian cortex to obtain live denuded oocytes from early-stage follicles. Our findings provide insights into the use of cryopreserved tissue and follicles for fertility preservation efforts.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by National Institutes of Health (NIH) R01HD099402, Career Training in Reproductive Biology (CTRB) Training Grant National Institutes of Health (NIH) T32 to Jordan Machlin, National Institutes of Health (NIH) F31-HD106626 and National Institutes of Health (NIH) T31H-D079342 to Andrea Jones, National Institutes of Health (NIH) T32-GM70449 to D. Ford Hannum, and The Chan Zuckerberg Initiative Grant CZF2019-002428. We have no conflicts of interest to declare.

First successful ovarian cortex allotransplant to a Turner syndrome patient requiring immunosuppression: wide implications

OBJECTIVE

To determine whether we can safely and successfully transplant an ovary tissue allograft from a nonidentical donor to her Turner syndrome sister.

DESIGN

Transplantation of cryopreserved ovary tissue, as well as fresh transplantation of ovarian tissue between identical twins, is now well established with numerous reported successful cases. However, there have not yet been any ovary transplants between nonidentical women requiring immunosuppression (ovary allotransplant). This could be a much more common indication for ovary tissue transplantation if safe and reliable immunosuppression were available.

PATIENT(S)

A 20-year-old amenorrheic woman with nonmosaic 45-XO Turner syndrome requested ovary tissue transplantation from her fertile 22-year-old 46-XX sister. They were an human leukocyte antigens match but were ABO incompatible, a well-known contra-indication to solid tissue or organ transplantation. The Turner syndrome sister strongly preferred to be able to become pregnant naturally without donor egg in vitro fertilization and to avoid hormone replacement therapy. In her religious group, that would also be important for finding a marital match. Despite the poor prognosis associated with ABO incompatibility, an ovary from her 22-year-old nonidentical fertile sister was transplanted to her employing the immunosuppression protocol now used for kidney transplant patients in our centers at Washington University and Johns Hopkins.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Post operatively at 5 months she developed normal monthly menstrual ovarian function, and she became spontaneously pregnant with a normal infant girl. The relation between her postoperation follicle stimulating hormone and antimüllerian hormone levels continue to support the theory that tissue pressure controls primordial follicle recruitment. The fact that ABO incompatibility did not prevent success suggests that diffusion and not revascularization may be all that is required for successful long-term ovarian cortex transplant survival with spontaneous pregnancy.

RESULT(S)

Ovary allotransplantation with safe immunosuppression allows natural conception, and also normal hormone function obviates the need for hormone replacement therapy. Orthotopic placement of the graft and surgical technique is critical for natural conception and a higher pregnancy rate.

CONCLUSION(S)

Allotransplantation requiring safe immunosuppression, if successful, maybe a much more commonly used indication for ovary transplantation in the future than frozen ovary grafts or grafts between identical twins.

Prospective solutions to ovarian reserve damage during the ovarian tissue cryopreservation and transplantation procedure

Birth rates continue to decline as more women experience fertility issues. Assisted reproductive technologies are available for patients seeking fertility treatment, including cryopreservation techniques. Cryopreservation can be performed on gametes, embryos, or gonadal tissue and can be used for patients who desire to delay in vitro fertilization treatment. This review focuses on ovarian tissue cryopreservation, the freezing of ovarian cortex containing immature follicles. Ovarian tissue cryopreservation is the only available treatment for the restoration of ovarian function in patients who undergo gonadotoxic treatments, and its wide adoption has led to its recent designation as "no longer experimental" by the American Society for Reproductive Medicine. Ovarian tissue cryopreservation and subsequent transplantation can restore native endocrine function and can support the possibility of pregnancy and live birth for the patient. Importantly, there are multiple steps in the procedure that put the ovarian reserve at risk of damage. The graft is highly susceptible to ischemic reperfusion injury and mass primordial follicle growth activation, resulting in a "burnout" phenomenon. In this review, we summarize current efforts to combat the loss of primordial follicles in grafts through improvements in freeze and thaw protocols, transplantation techniques, and pharmacologic adjuvant treatments. We conducted a review of the literature, with emphasis on emergent research in the last 5 years. Regarding freeze and thaw protocols, we discuss the widely accepted slow freezing approach and newer vitrification protocols. Discussion of improved transplantation techniques includes consideration of the transplantation location of the ovarian tissue and the importance of graft sites in promoting neovascularization. Finally, we discuss pharmacologic treatments being studied to improve tissue performance postgraft. Of note, there is significant research into the efficacy of adjuvants used to reduce ischemic injury, improve neovascularization, and inhibit hyperactivation of primordial follicle growth activations. Although the "experimental" label has been removed from ovarian tissue cryopreservation and subsequent transplantation, there is a significant need for further research to better understand sources of ovarian reserve damage to improve outcomes. Future research directions are provided as we consider how to reach the most hopeful results for women globally.

Microfluidic chips in female reproduction: a systematic review of status, advances, and challenges

The female reproductive system is essential to women's health, human reproduction and societal well-being. However, the clinical translation of traditional research models is restricted due to the uncertain effects and low efficiency. Emerging evidence shows that microfluidic chips provide valuable platforms for studying the female reproductive system, while no paper has ever comprehensively discussed the topic. Here, a total of 161 studies out of 14,669 records are identified in PubMed, Scopus, Web of Science, ScienceDirect and IEEE Xplore databases. Among these, 61 studies focus on oocytes, which further involves culture, cell surgeries (oocyte separation, rotation, enucleation, and denudation), evaluation and cryopreservation. Forty studies investigate embryo manipulation via microfluidic chips, covering in vitro fertilization, cryopreservation and functional evaluation. Forty-six studies reconstitute both the physiological and pathological statuses of in vivo organs, mostly involved in placenta and fetal membrane research. Fourteen studies perform drug screening and toxicity testing. In this review, we summarize the current application of microfluidic chips in studying the female reproductive system, the advancements in materials and methods, and discuss the future challenges. The present evidence suggests that microfluidic chips-assisted reproductive system reconstruction is promising and more studies are urgently needed.

Shear wave elastography to assess stiffness of the human ovary and other reproductive tissues across the reproductive lifespan in health and disease†

The ovary is one of the first organs to show overt signs of aging in the human body, and ovarian aging is associated with a loss of gamete quality and quantity. The age-dependent decline in ovarian function contributes to infertility and an altered endocrine milieu, which has ramifications for overall health. The aging ovarian microenvironment becomes fibro-inflammatory and stiff with age, and this has implications for ovarian physiology and pathology, including follicle growth, gamete quality, ovulation dynamics, and ovarian cancer. Thus, developing a non-invasive tool to measure and monitor the stiffness of the human ovary would represent a major advance for female reproductive health and longevity. Shear wave elastography is a quantitative ultrasound imaging method for evaluation of soft tissue stiffness. Shear wave elastography has been used clinically in assessment of liver fibrosis and characterization of tendinopathies and various neoplasms in thyroid, breast, prostate, and lymph nodes as a non-invasive diagnostic and prognostic tool. In this study, we review the underlying principles of shear wave elastography and its current clinical uses outside the reproductive tract as well as its successful application of shear wave elastography to reproductive tissues, including the uterus and cervix. We also describe an emerging use of this technology in evaluation of human ovarian stiffness via transvaginal ultrasound. Establishing ovarian stiffness as a clinical biomarker of ovarian aging may have implications for predicting the ovarian reserve and outcomes of Assisted Reproductive Technologies as well as for the assessment of the efficacy of emerging therapeutics to extend reproductive longevity. This parameter may also have broad relevance in other conditions where ovarian stiffness and fibrosis may be implicated, such as polycystic ovarian syndrome, late off target effects of chemotherapy and radiation, premature ovarian insufficiency, conditions of differences of sexual development, and ovarian cancer. Summary sentence:  Shear Wave Elastography is a non-invasive technique to study human tissue stiffness, and here we review its clinical applications and implications for reproductive health and disease.

In Vitro Maturation, In Vitro Oogenesis, and Ovarian Longevity

This paper will review a remarkable new approach to in vitro maturation "IVM" of oocytes from ovarian tissue, based on our results with in vitro oogenesis from somatic cells. As an aside benefit we also have derived a better understanding of ovarian longevity from ovary transplant. We have found that primordial follicle recruitment is triggered by tissue pressure gradients. Increased pressure holds the follicle in meiotic arrest and prevents recruitment. Therefore recruitment occurs first in the least dense inner tissue of the cortico-medullary junction. Many oocytes can be obtained from human ovarian tissue and mature to metaphase 2 in vitro with no need for ovarian stimulation. Ovarian stimulation may only be necessary for removing the oocyte from the ovary, but this can also be accomplished by simple dissection at the time of ovary tissue cryopreservation. By using surgical dissection of the removed ovary, rather than a needle stick, we can obtain many oocytes from very small follicles not visible with ultrasound. A clearer understanding of ovarian function has come from in vitro oogenesis experiments, and that explains why IVM has now become so simple and robust. Tissue pressure (and just a few "core genes" in the mouse) direct primordial follicle recruitment and development to mature oocyte, and therefore also control ovarian longevity. There are three distinct phases to oocyte development both in vitro and in vivo: in vitro differentiation "IVD" which is not gonadotropin sensitive (the longest phase), in vitro gonadotropin sensitivity "IVG" which is the phase of gonadotropin stimulation to prepare for meiotic competence, and IVM to metaphase II. On any given day 35% of GVs in ovarian tissue have already undergone "IVD" and "IVG" in vivo, and therefore are ready for IVM.

The Combination of Estradiol and N-Acetylcysteine Reduces Ischemia-Reperfusion Injuries of Mice Autografted Ovarian Tissue

Ischemia-reperfusion injuries are important issues after ovarian tissue transplantation (OTT). Our study examined the effects of N-acetylcysteine (NAC) and estradiol (E2) on mouse ovarian autografts. Mice (6-8 weeks) were divided into ovarian autograft as follows: Control: fresh OTT; Sham: cryopreserved/warmed OTT; NAC: cryopreserved/warmed OTT with NAC treatment; E2: cryopreserved/warmed OTT with E2 treatment; NAC+E2: cryopreserved/warmed OTT with the treatment of NAC and E2. In all groups, grafts were harvested on days 2, 7, and 28 after transplantation to evaluate histological parameters, inflammation relative to genes expression, and oxidative status. Histological analysis showed that NAC, E2, and a combination of NAC+E2 significantly increased the primordial, preantral, and antral follicular number. When NAC was used, it significantly reduced the expression of Tnf-α and Fgf-2, whereas it increased Il-1β, Il-6, and Vegf expression levels. The levels of Il-6, Fgf-2, and VEGF were dramatically increased in the E2-treated group. The combination of NAC and E2 significantly increased levels of Il-1β, Il-6, Fgf-2, and Vegf. NAC and E2 alone or in combination significantly increased total antioxidant capacity but did not affect the superoxide dismutase and glutathione peroxidase activities. In conclusion, after transplantation, NAC and E2 alone or in combination, could improve follicular development and angiogenesis as well as decline inflammation and ovarian oxidative damage.

Kisspeptin decreases the adverse effects of human ovarian vitrification by regulating ROS-related apoptotic occurrences

Kisspeptin is characterized as a neuropeptide with a pivotal function in female and male infertility, and its antioxidant properties have been demonstrated. In this study, the effects of kisspeptin on the improvement of the vitrification and thawing results of human ovarian tissues were investigated. In this work, 12 ovaries from patients who underwent hysterectomy were collected laparoscopically, and then 32 samples from each of their tissues were taken. Haematoxylin and eosin (H&E) staining was performed to check the normality of the ovarian tissue and, subsequently, the samples were allocated randomly into four groups, including: (1) fresh (control), (2) vitrification, (3) vitrified + 1 μM kisspeptin, and (4) vitrified + 10 μM kisspeptin groups. After vitrification, thawing, and tissue culture processes, H&E staining for tissue quality assessment, terminal deoxynucleotidyl transferase dUTP nick end labelling assay for apoptosis evaluation, and malondialdehyde (MDA), superoxide dismutase (SOD), and ferric reducing ability of plasma tests for oxidative stress appraisal were carried out. Our histological results showed incoherency of ovarian tissue morphology in the vitrification group compared with other groups. Other findings implicated increased apoptosis rate and MDA concentration and reduced SOD activity and total antioxidant capacity (TAC) in the vitrification group compared with the control group (P < 0.05). Moreover, decreased apoptosis rate and MDA concentration, and increased TAC and SOD function were observed in the vitrification with kisspeptin groups (1 μM and 10 μM) compared with the vitrified group (P < 0.05). Our reports express that kisspeptin is an effective agent to overcome the negative effects of vitrification by regulating reactive oxygen species-related apoptotic processes.

Impact of prepubertal bovine ovarian tissue pre-freeze holding duration on follicle quality

Ovarian tissue cryopreservation prior to gonadotoxic treatment is the only recommended option for fertility preservation in prepubertal girls. Due to the technical complexity of this technique, limited number of centres across the world are equipped to offer the facility. Hence, the retrieved ovarian tissue needs to be maintained at hypothermic temperature (4 °C) for long time during shipment. The time taken between tissue retrieval and cryopreservation could influence the functionality of cells during fertility restoration. This study explored the tissue integrity and follicle quality of ovarian cortical slices subjected to pre-freeze holding for various time durations in vitro. Prepubertal bovine ovarian tissue from < 12 months old animals were handled at hypothermic holding (4 °C) for 0, 24, 48 and 72 h. The tissues were assessed for follicle viability through confocal analysis of live-dead labelled samples, and follicle quality and tissue integrity through histology. Results have shown that follicle viability, and overall follicle quality were not significantly affected at the end of 72 h hypothermic holding. Though, the observation reassures extended hypothermic holding prior to freezing, findings need to be validated in human tissue prior to use in clinical fertility preservation programs.

Fertility preservation in pediatric healthcare: a review

Survival rates for children and adolescents diagnosed with malignancy have been steadily increasing due to advances in oncology treatments. These treatments can have a toxic effect on the gonads. Currently, oocyte and sperm cryopreservation are recognized as well-established and successful strategies for fertility preservation for pubertal patients, while the use of gonadotropin-releasing hormone agonists for ovarian protection is controversial. For prepubertal girls, ovarian tissue cryopreservation is the sole option. However, the endocrinological and reproductive outcomes after ovarian tissue transplantation are highly heterogeneous. On the other hand, immature testicular tissue cryopreservation remains the only alternative for prepubertal boys, yet it is still experimental. Although there are several published guidelines for navigating fertility preservation for pediatric and adolescent patients as well as transgender populations, it is still restricted in clinical practice. This review aims to discuss the indications and clinical outcomes of fertility preservation. We also discuss the probably effective and efficient workflow to facilitate fertility preservation.

Novel Approaches Used in Ovarian Tissue Transplantation for Fertility Preservation: Focus on Tissue Engineering Approaches and Angiogenesis Capacity

Due to the impact of the modern lifestyle, female infertility has been reduced because of different reasons. For example, in combined chemotherapeutic therapies, a small fraction of cancer survivors has faced different post-complications and side effects such as infertility. Besides, in modern society, delayed age of childbearing has also affected fertility. Nowadays, ovarian tissue cryopreservation and transplantation (OTC/T) is considered one of the appropriate strategies for the restoration of ovarian tissue and bioactivity in patients with the loss of reproductive function. In this regard, several procedures have been considered to improve the efficacy and safety of OTT. Among them, a surgical approach is used to transplant ovaries into the optimal sites, but the existence of ischemic changes and lack of appropriate revascularization can lead to bulk follicular atresia. Besides, the role of OTC/T is limited in women of advanced maternal age undergoing lifesaving chemo-radiation. As a correlate, the development of de novo approaches with efficacious regenerative outcomes is highly welcomed. Tissue engineering shows high therapeutic potentialities to restore fertility in males and females using the combination of biomaterials, cells, and growth factors. Unfortunately, most synthetic and natural materials are at the experimental stage and only the efficacy has been properly evaluated in limited cases. Along with these descriptions, strategies associated with the induction of angiogenesis in transplanted ovaries can diminish the injuries associated with ischemic changes. In this review, the authors tried to summarize recent techniques, especially tissue engineering approaches for improving ovarian function and fertility by focusing on angiogenesis and neovascularization.

Three major reasons why transgenerational effects of radiation are difficult to detect in humans

PURPOSE

Ionizing radiation can induce mutations in germ cells in various organisms, including fruit flies and mice. However, currently, there is no clear evidence for the transgenerational effects of radiation in humans. This review is an effort to identify possible reasons for the lack of such observations.

METHODS

Literature search and narrative review.

RESULTS

1) In both mice and humans, resting oocytes locate primarily in the cortical region of the ovary where the number of blood vessels is very low especially when young and extra-cellular material is rich, and this region is consequently hypoxic, which probably leads to immature oocytes being resistant to the cell killing and mutagenic effects of radiation. 2) In studies of spermatogonia, the mouse genes used for specific locus test (SLT) studies, which include coat color genes, were hypermutable when compared to many other genes. Recent studies which examined over 1000 segments of genomic DNA indicate that the induction rate of deletion mutation per segment was on the order of 10-6 per Gy, which is one order of magnitude lower than that obtained from the SLT data. Therefore, it appears possible that detecting any transgenerational effects of radiation following human male exposures will be difficult due to a lack of mutable marker genes. 3) Fetal malformations were examined in studies in humans, but the genetic component in such malformations is low, and abnormal fetuses are prone to undergo miscarriage which does not occur in mice, and which leads to difficulties in detecting transgenerational effects.

CONCLUSION

The lack of clear evidence for radiation effects in humans probably does not result from any problem in the methodologies used but may be due largely to biological properties. Currently, whole genome sequencing studies of exposed parents and offspring are planned, but ethical guidelines need to be followed to avoid discrimination, which had once happened to the atomic bomb survivors.

A bioengineered in situ ovary (ISO) supports follicle engraftment and live-births post-chemotherapy

Female cancer patients who have undergone chemotherapy have an elevated risk of developing ovarian dysfunction and failure. Experimental approaches to treat iatrogenic infertility are evolving rapidly; however, challenges and risks remain that hinder clinical translation. Biomaterials have improved in vitro follicle maturation and in vivo transplantation in mice, but there has only been marginal success for early-stage human follicles. Here, we developed methods to obtain an ovarian-specific extracellular matrix hydrogel to facilitate follicle delivery and establish an in situ ovary (ISO), which offers a permissive environment to enhance follicle survival. We demonstrate sustainable follicle engraftment, natural pregnancy, and the birth of healthy pups after intraovarian microinjection of isolated exogenous follicles into chemotherapy-treated (CTx) mice. Our results confirm that hydrogel-based follicle microinjection could offer a minimally invasive delivery platform to enhance follicle integration for patients post-chemotherapy.

Bone marrow mesenchymal stem cells in premature ovarian failure: Mechanisms and prospects

Premature ovarian failure (POF) is a common female reproductive disorder and characterized by menopause, increased gonadotropin levels and estrogen deficiency before the age of 40 years old. The etiologies and pathogenesis of POF are not fully clear. At present, hormone replacement therapy (HRT) is the main treatment options for POF. It helps to ameliorate perimenopausal symptoms and related health risks, but can't restore ovarian function and fertility fundamentally. With the development of regenerative medicine, bone marrow mesenchymal stem cells (BMSCs) have shown great potential for the recovery of ovarian function and fertility based on the advantages of abundant sources, high capacity for self-renewal and differentiation, low immunogenicity and less ethical considerations. This systematic review aims to summarize the possible therapeutic mechanisms of BMSCs for POF. A detailed search strategy of preclinical studies and clinical trials on BMSCs and POF was performed on PubMed, MEDLINE, Web of Science and Embase database. A total of 21 studies were included in this review. Although the standardization of BMSCs need more explorations, there is no doubt that BMSCs transplantation may represent a prospective therapy for POF. It is hope to provide a theoretical basis for further research and treatment for POF.

Medical Grade Honey as a Promising Treatment to Improve Ovarian Tissue Transplantation

Ovarian tissue cryopreservation is a female fertility preservation technique that presents major challenges for the maintenance of follicular viability after transplantation. The aim of this study was to evaluate and compare the application of L-Mesitran Soft®, a product containing 40% medical grade honey (MGH), with other strategies to improve ovarian grafts' viability. For this purpose, bovine ovarian tissue was vitrified, warmed and randomly assigned to culture groups: (1) control, (2) MGH 0.2% in vitro, (3) MGH in vivo (direct application in the xenotransplantation), (4) vascular endothelial growth factor (VEGF 50 ng/mL) and (5) vitamin D (100 Nm), during a 48 h period. A sixth group (6) of fragments was thawed on transplantation day and was not cultured. The tissue was xenotransplanted into immunodeficient (Rowett nude homozygous) ovariectomized rats. Grafts were analyzed 48 h after culture, and 7 and 28 days after transplantation. The tissue was subjected to histological and immunohistochemical analysis. Treatments using MGH showed the highest angiogenic and cell proliferation stimulation, with cellular apoptosis, within a healthy cellular turnover pathway. In conclusion, MGH should be considered as a potentially effective and less expensive strategy to improve ovarian tissue transplantation.

Age-related fertility decline: is there a role for elective ovarian tissue cryopreservation?

Age-related fertility decline (ARFD) is a prevalent concern amongst western cultures due to the increasing age of first-time motherhood. Elective oocyte and embryo cryopreservation remain the most established methods of fertility preservation, providing women the opportunity of reproductive autonomy to preserve their fertility and extend their childbearing years to prevent involuntary childlessness. Whilst ovarian cortex cryopreservation has been used to preserve reproductive potential in women for medical reasons, such as in pre- or peripubertal girls undergoing gonadotoxic chemotherapy, it has not yet been considered in the context of ARFD. As artificial reproductive technology (ART) and surgical methods of fertility preservation continue to evolve, it is a judicious time to review current evidence and consider alternative options for women wishing to delay their fertility. This article critically appraises elective oocyte cryopreservation as an option for women who use it to mitigate the risk of ARFD and introduces the prospect of elective ovarian cortex cryopreservation as an alternative.

In-vitro maturation and transplantation of cryopreserved ovary tissue: understanding ovarian longevity

RESEARCH QUESTION

Is it possible to use experience gained from 24 years of frozen ovarian transplantation, and from recent experience with in-vitro gametogenesis to accomplish simple and robust in-vitro maturation (IVM) of oocytes from human ovarian tissue?

DESIGN

A total of 119 female patients between age 2 and 35 years old underwent ovary cryopreservation (as well as in-vitro maturation of oocytes and IVM in the last 13 individuals) over a 24-year period. Up to 22 years later, 17 returned to have their ovary tissue thawed and transplanted back.

RESULTS

Every woman had a return of ovarian function 5 months after transplant, similar to previous observations. As observed before, anti-Müllerian hormone (AMH) concentration rose as FSH fell 4 months later. The grafts continued to work up to 8 years. Of the 17, 13 (76%) became pregnant with intercourse at least once, resulting in 19 healthy live births, including six live births from three women who had had leukaemia. Of the harvested germinal vesicle oocytes, 35% developed with simple culture media into mature metaphase II oocytes.

CONCLUSIONS

The authors concluded the following. First, ovary tissue cryopreservation is a robust method for preserving fertility even for women with leukaemia, without a need to delay cancer treatment. Second, many mature oocytes can often be obtained from ovary tissue with simple media and no need for ovarian stimulation. Third, ovarian stimulation only be necessary for removing the oocyte from the ovary, which can also be accomplished by simple dissection at the time of ovary freezing. Finally, pressure and just eight 'core genes' control primordial follicle recruitment and development.

Female Oncofertility: Current Understandings, Therapeutic Approaches, Controversies, and Future Perspectives

Recent advances in early detection and oncological therapies have ameliorated the survival rate of young cancer patients. Yet, ovarian impairment induced by chemotherapy and radiotherapy is still a challenging issue. This review, based on clinical and lab-based studies, summarizes the evidence of gonadotoxicity of chemoradiotherapy, the recent approaches, ongoing controversies, and future perspectives of fertility preservation (FP) in female patients who have experienced chemo- or radio-therapy. Existing data indicate that chemotherapeutic agents induce DNA alterations and massive follicle activation via the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. Meanwhile, the radiation causes ionizing damage, leading to germ cell loss. In addition to the well-established methods, numerous therapeutic approaches have been suggested, including minimizing the follicle loss in cryopreserved ovarian grafts after transplantation, in vitro activation or in vitro growing of follicles, artificial ovarian development, or fertoprotective adjuvant to prevent ovarian damage from chemotherapy. Some reports have revealed positive outcomes from these therapies, whereas others have demonstrated conflictions. Future perspectives are improving the live birth rate of FP, especially in patients with adverse ovarian reserve, eliminating the risk of malignancy reintroducing, and increasing society’s awareness of FP importance.

Ovarian tissue features assessed in bovine fetuses after vitrification and xenotransplantation procedures

Cryopreservation and transplantation of ovarian tissue are proposed methods for the restoration of endocrine function and reproductive potential. Therefore, this study aimed to evaluate the effects of vitrification and xenotransplantation on follicle viability, activation, stromal cell integrity, vascularization, and micronuclei formation. Bovine fetal ovaries were fragmented and assigned to the following groups: Fresh control (FC), ovarian fragments immediately fixed; Vitrified control (VC), ovarian fragments vitrified; Vitrified xenotransplanted (VX), ovarian fragments vitrified and xenotransplanted; and Fresh xenotransplanted (FX), ovarian fragments xenotransplanted. Ovarian fragments were grafted in female BALB/c mice and recovered after 14 days. Follicular viability was preserved (P >  0.05) in VC group. The rate of developing follicles was greater (P <  0.05) in the FX group compared to other groups. Follicular density was higher (P <  0.05) in the VC group than the FC, VX, and FX groups. A decrease (P <  0.05) of stromal cell density was recorded after vitrification (VC vs. FX). Blood vessel density decreased in VC, VX, and FX groups compared with the FC group, and blood vessel density was correlated with follicular viability (positively; P =  0.07) and developing follicles (negatively; P <  0.001). Both vitrification and xenotransplantation groups (VC, VX, and FX) had a greater (P <  0.05) number of cells with one MN compared to the FC group. In summary, our findings showed that both vitrification and xenotransplantation modified blood vessel, follicular and stromal cell densities, follicular viability and activation, and micronuclei formation in ovarian tissue.

Post-thawing and culture comparison of three routine slow freezing methods for human ovarian tissue cryopreservation: Histological, molecular, and hormonal aspects

To find the gold standard out of three pre-established routine slow freezing (SF) methods, ovarian cortex tissues of nine transsexual individuals were cryopreserved and compared to each other, as well as the control (fresh) samples. Histological, genomic, and endocrinological effects of the SFs were assessed post-thawing and after a seven-day culture period. SF1 included 10% dimethyl-sulfoxide (Me2SO) in the base medium (BM), SF2 had 1.5 M/L ethylene-glycol (EG) and 0.1 M/L sucrose in the BM, and SF3 consisted of 6% Me2SO, 6% EG and 0.15 M/L sucrose in the BM. The cortical tissue strips went under a programmed cooling process and were stored in liquid nitrogen. Histological criteria (tissue damage and follicular quality), as well as gene expression levels, were assessed in the thawed and control tissues. Half of the thawed and control tissues were cultured for seven days and their histology, genetic profile, and hormonal status were examined as the reflection of the avascular tension effect. Post-thawing tissue damage was similar between all groups but significantly increased post-culture (P < 0.05). The percentages of high-quality follicles diminished in all SFs after thawing and culture (P < 0.05) except for the similarity of post-thawing SF3, compared to control. The genetic profile of the tissue after thawing and culture suggested quiescence/activation balance in SF1 and 2 and significant down-regulation in SF3, compared to the control specimens (P < 0.05). Post-thawing BAX:BCL2 was higher than control in SF1 and SF3 (P < 0.05), while this ratio in SF2 was similar to the control. However, after culture this ratio was similar to that of control in SF3 and diminished in SF1 and 2 (P < 0.05). The expression levels of gap-junction genes showed dramatic pre- and post-thawing fluctuations in all groups. After culture, estradiol in SF3 was significantly higher than SF1 and 2 (P < 0.05). In addition, progesterone in SF3 was similar to control but significantly lower in SF1 and 2 (P < 0.05). In conclusion, all SFs showed advantages and disadvantages, and the follicular quality and its function depend on the type of cryoprotectant and the speed of thawing. The effects of freezing/thawing continue to appear during the seven days of culture. According to the results of this study, SF3 seems to be more promising in keeping the follicles functional and safe from cell damage during culture.

Applying plastic surgery principles to ovarian tissue transplantation

Ovarian tissue cryopreservation (OTC) and transplantation is an innovative procedure increasingly utilized to help preserve fertility after gonadotoxic treatments especially in cancer patients. Approximately 30% of autotransplanted patients are able to achieve live birth, typically with the help of in-vitro fertilization. Numerous techniques and grafting sites have been described to continue to increase this figure. In the field of plastic surgery, tissue grafting has been successful performed for thousands of years and knowledge in this area has been significantly refined. A qualitative review of the literature using PubMed, Cochrane, SCOPUS and Medline databases was performed to look for articles relating to ovarian tissue transplantation (OTT) and comparisons made to plastic surgery tissue grafting. Many parallels were found between the principles of grafting in plastic surgery and the principles of OTT, including pre-operative patient optimization, suitable donor site selection, tissue harvest and preparation, graft site choice, immobilization of the graft and post-operative care. Consideration of the benefits and risks of using orthotopic versus heterotopic recipient sites is also highly important with regards to graft take, morbidity and ease of access of oocyte collection. We believe that ongoing discussion between disciplines can have the potential to improve knowledge, surgical techniques and patient outcomes.

Autotransplantation of the ovarian cortex after in-vitro activation for infertility treatment: a shortened procedure

STUDY QUESTION

Is it possible to establish a new in-vitro activation (IVA) protocol for infertility treatment?

SUMMARY ANSWER

A new IVA procedure is an efficient and easily performed approach for infertility treatment of patients with diminished ovarian reserve (DOR).

WHAT IS KNOWN ALREADY

IVA of primordial follicles with or without stimulators has been developed to treat patients with primary ovarian insufficiency (POI) successfully. However, the efficiency of the procedure is still very low. There is a requirement to optimize the protocol with increased efficiency for clinical application.

STUDY DESIGN, SIZE, DURATION

Newborn mouse ovaries were used to establish a new 1-h IVA protocol with the mechanistic target of rapamycin (mTOR) stimulator phosphatidic acid (PA, 200 µM) and the phosphatidylinositol-3-kinase (PI3K) stimulator 740Y-P (250 µg/ml); a prospective observational cohort study in POI patients was performed on 15 POI patients and 3 poor ovarian response (POR) patients in three different centers of reproductive medicine in China.

PARTICIPANTS/MATERIALS, SETTING, METHODS

One-third of ovarian cortex was removed and processed into bigger strips (1 × 1 cm2, 1-2 mm thickness). Strips were then sutured back after treatment. The new approach only requires one laparoscopic surgery.

MAIN RESULTS AND THE ROLE OF CHANCE

Follicular activation and development increased in cultured mouse and human ovarian tissues after 1 h of stimulator treatment. Compared with tiny ovarian cortex pieces (1 × 1 mm2), large ovarian strips (1 × 1 cm2) showed the lowest apoptotic signals after incubation. We applied the orthotropic transplantation procedure with large strips in the clinic, and 9 of 15 POI patients showed at least one-wave follicular growth during the monitoring period. One patient was reported with one healthy delivery after natural conception and another patient with a healthy singleton delivery after IVF. All the contacted patients (n = 13) responded with no side effects on their health 2-4 years after IVA procedure.

LIMITATIONS, REASONS FOR CAUTION

Further clinical trials with a large number of well-defined patients are required to compare different IVA protocols. A long-term follow-up system should be set up to monitor patient's health in the future cohort study.

WIDER IMPLICATIONS OF THE FINDINGS

By using stimulators, the findings in the study provide a more efficient IVA protocol for the treatment of patients with DOR. It requires only one laparoscopic surgery and thus minimizes patients' discomfort and costs. This strategy could be useful for patients diagnosed with POI and desire pregnancy as soon as possible after the operation.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Key Research and Development Program of China (2018YFC1003703 and 2018YFC1004203); the National Natural Science Foundation of China (81871221); Co-construction of Provincial Department (201601006). The authors have no conflict of interest to disclose.

TRIAL REGISTRATION NUMBER

ChiCTR2000030872.

Novel Approaches in Addressing Ovarian Insufficiency in 2019: Are We There Yet?

Ovarian insufficiency is described as a multifaceted issue typically encountered in the field of assisted reproduction. The three main identified diagnoses of ovarian insufficiency include premature ovarian failure (POF), poor ovarian response (POR), and advanced maternal age (AMA). Patient heterogeneity in the era of individualized medicine drives research forward leading to the emergence of novel approaches. This plethora of innovative treatments in the service of adequately managing ovarian insufficiency is called to undertake the challenge of addressing infertile patients exploring their reproductive options. This review provides an all-inclusive presentation and critical analysis on novel treatments that have not achieved routine clinical practice status yet, but have recently emerged as promising. In light of the lack of randomized controlled trials conveying safety and efficiency, clinicians are left puzzled in addressing the "how" and "for whom" these approaches may be beneficial. From ovarian injection employing platelet-rich plasma (PRP) or stem cells to artificial gametes and ovaries, ovarian transplantation, and mitochondrial replacement therapy, this descriptive review provides insight toward assisting the practitioner in decision making regarding these cutting-edge treatments. Biological mechanisms, invasiveness levels, efficiency, as well as possible complications, the current status along with bioethical concerns are discussed in the context of identifying future optimal treatment.

Therapeutic Angiogenesis for Ovarian Transplantation through Ultrasound-Targeted Microbubble Destruction

Timely angiogenesis and effective microcirculation perfusion are essential for the survival and functional recovery of transplanted ovaries. Ultrasound-targeted microbubble destruction (UTMD) can lead to angiogenesis and increase flow perfusion by causing transient inflammation. The purpose of this study was to evaluate the effects of UTMD on transplanted ovarian revascularization and survival. In vitro, for the criteria of cell viability and tube formation capability, the optimal exposure parameters were determined to be a microbubble concentration of 1 × 10⁸/mL, mechanical index of 1 and exposure time of 30 s. After ovarian transplantation, 40 female Sprague Dawley rats were divided into four groups: transplantation alone, ultrasound alone, microbubbles alone and ultrasound and microbubbles (UTMD). At 7 d after transplantation, ovarian perfusion was assessed using qualitative and quantitative methods. The effect of angiogenesis was assessed by contrast-enhanced ultrasound, laser Doppler perfusion imaging and histologic analysis. The results, in which ovarian perfusion was highest in the UTMD group, suggest that UTMD can effectively improve ovarian perfusion. Compared with the other three groups, the number of follicles, microvascular density and rate of Ki-67-positive cells increased significantly in the UTMD group, while apoptosis decreased significantly (p < 0.05). The study indicates that UTMD promoted ovarian re-vascularization after ovarian transplantation and maintained follicular reserve.

Cryopreservation and Transplantation of Laboratory Rodent Ovarian Tissue for Genome Banking and Biomedical Research

Genetic modifications in combination with highly sophisticated assisted reproductive technologies such as in vitro oocyte maturation and development, in vitro fertilization, intracytoplasmic sperm injection, and in vitro embryo culture have opened many research avenues and treatment options for both animals and humans. The number of genetically modified (GM) rodent strains increased considerably during the last several decades, and their numbers are expected to increase due to efficient gene editing technologies including the CRISPR/Cas9. Rodent ovarian tissues (OT) cryopreservation and transplantation procedures have several applications in biomedical field: they provide a fertility restoration option for GM rodent strains in some circumstances. They also serve as models to investigate OT cryopreservation as potential alternatives for human infertility patients as well as other domestic and wildlife species for the development of improved cryopreservation and subsequent transplantation strategies. The modeling studies enable determining effective cryoprotective agents (CPA), CPA and water permeability kinetics, and cooling and warming rates during the development of OT cryopreservation procedures. Furthermore, rodent models are extremely useful for determining post-thaw OT graft sites as well as potential medical interventions in an effort to expedite angiogenesis and inhibit inflammatory/immune response, OT longevity, and follicular integrity. Here we describe methodologies for rodent OT cryopreservation and potential transplantation sites for frozen-thawed rat and mouse OT.

Preservation of connexin 43 and transzonal projections in isolated bovine pre-antral follicles before and following vitrification

PURPOSE

Gap junctions and transzonal projections play a crucial role in intercellular communication between different follicular components and are necessary for follicle development. We aimed to demonstrate gap junction protein connexin 43 (Cx43) and transzonal projections (TZPs) in viable, category 1, isolated bovine pre-antral follicles (PAFs) during short-term culture and after vitrification and warming.

METHODS

This study involved four experimental groups: fresh control, 2-day culture, 4-day culture, and vitrified secondary PAFs. Isolated PAFs were vitrified using a simple and efficient cryopreservation method by means of mini cell strainers.

RESULTS

Cx43 and TZPs were detected in pre-antral follicles of all stages, as well as in every experimental group. The group fresh follicles showed a higher percentage of follicles that were positive for Cx43 (91.7%) than the follicles that were vitrified (77.4%). All follicles that were cultured for 2 days were Cx43-positive (100%). Follicles cultured for 4 days (65.8%) (P = 0.002) showed the lowest percentage of follicles that were Cx43-positive. The percentages of the presence or (partial) absence of the TZP network were shown to be very heterogeneous between follicles in different treatment groups.

CONCLUSIONS

These results suggest the maintenance of communication between the oocyte and the somatic companion cells after vitrification and warming. The varying percentages of the expression of the TZP network within groups suggests that it will be of interest to investigate whether this is truly due to variability in TZP integrity and follicle quality or due to methodological limitations.

Changes in telomere length and senescence markers during human ovarian tissue cryopreservation

Ovarian tissue cryopreservation is considered as a useful option to preserve fertility for cancer patients. This study purposed to evaluate the change of telomere length and senescence markers during human ovarian tissue cryopreservation. Ovarian tissues were obtained from women who underwent benign ovarian surgery in the gynecology research unit of a university hospital with prior consent and IRB approval. DNA was extracted from the ovarian tissues using a DNeasy tissue kit and telomere lengths in the DNA samples were determined by real time PCR before and after cryopreservation. All tissues were stained with hematoxylin–eosin and subjected to immunohistochemistry and TUNEL assays. Other senescence markers, including p53, p16, p21, and phospho-pRb proteins, were evaluated using western blot analysis. Ovarian tissues were collected from ten patients and prepared for slow freezing with the same size of diameter 4 mm and 1 mm thickness. Mean age of patients was 26.7 ± 6.2 years (range, 16–34 years), and ovarian tissues were cryopreserved and thawed 4 weeks after cryopreservation. The mean telomere length was significantly decreased after cryopreservation (9.57 ± 1.47 bp vs. 8.34 ± 1.83 bp, p = 0.001). Western blot analysis revealed that p53, p16, and p21 proteins increased and phospho-pRb protein expression decreased after ovarian tissue cryopreservation. Ovarian tissue cryopreservation and transplantation is regarded as one of promising options for fertility preservation. However, clinicians and researchers should be aware of possible irreversible DNA changes such as shortening of telomere length and alterations of other senescence markers in human ovarian tissues.

Cryopreservation as a Key Element in the Successful Delivery of Cell-Based Therapies-A Review

Cryopreservation is a key enabling technology in regenerative medicine that provides stable and secure extended cell storage for primary tissue isolates and constructs and prepared cell preparations. The essential detail of the process as it can be applied to cell-based therapies is set out in this review, covering tissue and cell isolation, cryoprotection, cooling and freezing, frozen storage and transport, thawing, and recovery. The aim is to provide clinical scientists with an overview of the benefits and difficulties associated with cryopreservation to assist them with problem resolution in their routine work, or to enable them to consider future involvement in cryopreservative procedures. It is also intended to facilitate networking between clinicians and cryo-researchers to review difficulties and problems to advance protocol optimization and innovative design.

Effect of Selenium on Expression of Apoptosis-Related Genes in Cryomedia of Mice Ovary after Vitrification

Introduction

Freezing of ovarian tissue is used for preservation of fertility. The freezing-thawing process is accompanied by oxidative stress and induction of apoptosis. Apoptosis is a complex process that has been studied in animal models. The present study was aimed at investigating the effect of selenium on suppression of apoptosis during vitrification-thawing process of mice ovary via studying expression of apoptosis-related genes, and also, we aimed to design statistical models for the roles of single genes and gene-gene interactions in suppression of apoptosis.

Methods

A total of 10 right ovary samples from 10 mice were randomly divided into two groups of selenium treatment (at dose 5 μg/ml sodium selenite, through adding to the media) and control group. Vitrification-thawing process was done according to the existed protocols. Real-time PCR was used for gene expression study. The apoptosis gene profile included P53, Bax, Fas, and Bcl-2. General linear model was applied to study single gene associations and gene-gene interactions.

Results

From the studied genes, P53 showed a significant downregulation in the selenium group in comparison to the control group (∆∆CT = 1.96; P = 0.013; relative expression (RE) = 0.28). Bcl-2 showed a significant upregulation in the selenium group in comparison to the control group (∆∆CT = −2.49; P < 0.001; RE = 3.49). No significant result was found for other genes. According to the multiple models, Bcl-2 showed a protective single gene association (beta = −0.33; P = 0.032), and Fas∗Bcl-2 interaction was significantly positive (beta = 0.19; P = 0.036).

Conclusion

Addition of selenium to cryomedia of vitrification-thawing process could reduce the apoptosis induced by freezing-thawing stress in mice ovary via downregulation of P53 and upregulation of Bcl-2 at transcription level. Multivariable statistical models should be performed in future researches to study biological systems.

Optimizing ovarian tissue quality before cryopreservation: comparing outcomes of three decortication methods on stromal and follicular viability

OBJECTIVE

To evaluate whether specific ovarian decortication techniques vary in promoting ovarian cortex cryopreservation and transplant outcomes.

DESIGN

Experimental design.

SETTING

University hospital.

ANIMAL(S)

Nonobese diabetic (NOD)/severe combined immunodeficiency (SCID) female mice.

INTERVENTION(S)

Human ovarian biopsy samples allocated to one of the following decortication procedures: scratching with scalpel blade (B), cutting with microsurgical scissors (M), separation with slicer (S), or no-separation (control, C). Parallel, in vivo experiment: decortication techniques combined with slow freezing (SF) and vitrification (VT) before xenograft into immunodeficient mice.

MAIN OUTCOME MEASURE(S)

Follicular counts, apoptosis, shear stress, Hippo pathway and inflammation. In vivo: recovered grafts analyzed for follicular counts, angiogenesis, proliferation, and fibrosis.

RESULT(S)

There were no differences in follicular density or number of damaged follicles between the decortication techniques in the in vitro study. Nevertheless, the M samples showed statistically significantly increased stromal damage compared with the controls and S samples, and up-regulation of Hsp60 shear stress gene expression. Decortication by both M and S inhibited the Hippo pathway, promoting gene expression changes. In the 21-day xenograft, total follicular density statistically significantly decreased compared with the nongrafted controls in all groups. Nevertheless, no differences were observed between the decortication techniques. Ovarian stroma vascularization was increased in the vitrified samples, but among the slow-freezing samples, the B samples had the lowest microvessel density. The M decorticated xenografts had increased fibrosis.

CONCLUSION(S)

Decortication with a slicer causes less damage to ovarian tissue than other commonly used methods although microsurgical scissors seem to preserve slightly increased follicular numbers. Nevertheless, blade decortication seems to be a reliable technique for maintaining acceptable follicular conditions without inducing serious stromal impairment.

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.

Placenta-Derived Mesenchymal Stem Cells Restore the Ovary Function in an Ovariectomized Rat Model via an Antioxidant Effect

Oxidative stress is one of the major etiologies of ovarian dysfunction, including premature ovarian failure (POF). Previous reports have demonstrated the therapeutic effects of human placenta-derived mesenchymal stem cells (PD-MSCs) in an ovariectomized rat model (OVX). However, their therapeutic mechanism in oxidative stress has not been reported. Therefore, we investigated to profile the exosome of serum and demonstrate the therapeutic effect of PD-MSCs transplantation for the ovary function. We established an OVX model by ovariectomy and PD-MSCs transplantation was conducted by intravenous injection. Additionally, various factors in the exosome were profiled by LC-MS analysis. As a result, the transplanted PD-MSCs were engrafted into the ovary and the existence of antioxidant factors in the exosome. A decreased expression of oxidative stress markers and increased expression of antioxidant markers were shown in the transplantation (Tx) in comparison to the non-transplantation group (NTx) (* p < 0.05). The apoptosis factors were decreased, and ovary function was improved in Tx in comparison to NTx (* p < 0.05). These results suggest that transplanted PD-MSCs restore the ovarian function in an OVX model via upregulated antioxidant factors. These findings offer new insights for further understanding of stem cell therapy for reproductive systems.

Ultrasound Shear Wave Velocity Varies Across Anatomical Region in Ex Vivo Bovine Ovaries

The physical properties of the ovarian extracellular matrix (ECM) regulate the function of ovarian cells, specifically the ability of the ovary to maintain a quiescent primordial follicle pool while allowing a subset of follicles to grow and mature in the estrous cycle. Design of a long-term, cycling artificial ovary has been hindered by the limited information regarding the mechanical properties of the ovary. In particular, differences in the mechanical properties of the two ovarian compartments, the cortex and medulla, have never been quantified. Shear wave (SW) ultrasound elastography is an imaging modality that enables assessment of material properties, such as the mechanical properties, based on the velocity of SWs, and visualization of internal anatomy, when coupled with B-mode ultrasound. We used SW ultrasound elastography to assess whole, ex vivo bovine ovaries. We demonstrated, for the first time, a difference in mechanical properties, as inferred from SW velocity, between the cortex and medulla, as measured along the length (cortex: 2.57 ± 0.53 m/s, medulla: 2.87 ± 0.77 m/s, p < 0.0001) and width (cortex: 2.99 ± 0.81 m/s, medulla: 3.24 ± 0.97 m/s, p < 0.05) and that the spatial distribution and magnitude of SW velocity vary between these two anatomical planes. This work contributes to a larger body of literature assessing the mechanical properties of the ovary and related cells and specialized ECMs and will enable the rational design of biomimetic tissue engineered models and durable bioprostheses. Impact Statement Shear wave (SW) ultrasound elastography can be used to simultaneously assess the material properties and tissue structures when accompanied with B-mode ultrasound. We report a quantitative difference in mechanical properties, as inferred from SW velocity, between the cortex and medulla, with SW velocity being 11.4% and 8.4% higher in the medulla than the cortex when measured along the length and width, respectively. This investigation into the spatial and temporal variation in SW velocity in bovine ovaries will encourage and improve design of more biomimetic scaffolds for ovarian tissue engineering.

Exogenous luteinizing hormone promotes ovarian survival and function during cryopreservation and transplantation

Cryopreservation and transplantation of the ovarian tissue is an alternative method by which malignant tumor survivors can recover fertility. Previously, it was reported that follicle stimulating hormone (FSH) promoted the survival and functioning of the ovarian tissue after in vitro cultivation. In this study, the expression of the luteinizing hormone receptor (LHR) was observed on the granule cell membrane after luteinizing hormone (LH) (0.3 IU/mL) was supplied as an exogenous hormone into the cultivation medium during ovarian vitrification in the postnatal period (PND) (1, 7, 14, 21, 28, 42, and 56 days PND). The expression of vascular endothelial growth factor (VEGF) and Connexins (Cx), and the recovery of ovarian functions were then assessed in mice models. The results showed that LH increased the production of normal follicles, and upregulated the expression of VEGF, Cx37, and Cx43 in vitrified ovaries. LH administration also shortened the recovery time of the estrus cycle in mice models. Additionally, no difference was observed in the rate of pregnancy and size of the first litter between the experimental and control groups. In conclusion, LH could promote the survival and functioning of the ovaries by upregulating the expression of VEGF, Cx43, and Cx37 during ovarian cryopreservation and transplantation.

Vitrification technique for female germinative tissue cryopreservation and banking

Objective

To report on a device designed for the vitrification of germinative tissue, and a systematic vitrification/warming protocol.

Methods

We obtained six fragments of cortical germinative tissue from a human ovary. We randomly chose two fragments and sent them to histological analysis. We vitrified four test samples and stored them for one week in liquid nitrogen (LN), and warmed one week later. We sent the vitrified/warmed fragments to the pathology laboratory, where they analyzed them morphologically under an optical microscope (10-40X). They analyzed the nuclear and cytoplasmic characteristics of the follicular cells, luteal layer, and stroma. The primordial and primary follicles in the fresh and vitrified/warmed fragments were counted and compared with the Mann-Whitney test (p<0.05).

Results

There were ovarian follicles in different phases of maturation in both fresh and vitrified/warmed fragments, with a predominance of healthy-looking primordial and primary follicles. In the test fragments, the fusocellular architecture supporting the stromal cells exhibited some foci of edema, and were associated with cells with hydropic degeneration, with cytoplasmic fragmentation and eosinophilia. However, there were no signs of tissue necrosis or autolysis. There was no statistically significant difference between the number of follicles found in the control and test tissue fragments (p>0.05).

Conclusions

There were no significant morphological changes between fresh and vitrified/warmed germinative tissue. The vitrification device and protocol tested were effective in the preservation of human follicles, and should be considered for the banking germinative tissue for the restoration of fertility of women who are submitted to life-saving sterilizing treatments.

Pretreatment of ovaries with collagenase before vitrification keeps the ovarian reserve by maintaining cell-cell adhesion integrity in ovarian follicles

The mammalian ovarian follicle is comprised of the germ cell or oocyte surrounded by the somatic cells, the granulosa and theca cells. The ovarian stroma, including the collagen-rich matrix that supports the three-dimensional disk-like follicular structure, impacts the integrity of the ovarian follicle and is essential for follicular development. Maintaining follicular integrity during cryopreservation has remained a limiting factor in preserving ovarian tissues for transplantation because a significant proportion of developed follicles in the frozen-thawed ovaries undergo atresia after transplantation. In this study, we show for the first time that during vitrification of the mouse ovary, the attachment of the oocyte to the granulosa cells was impaired by the loss of the cadherin adhesion molecules. Importantly, exposure to a high osmotic solution greatly decreased the ratio of oocyte diameter to the diameter of its follicle but did not alter the collagen-rich matrix surrounding the follicles. By treating ovaries briefly with collagenase before exposure to the hyper-osmotic solution the ratio of oocyte diameter to follicle diameter was maintained, and cadherin adhesion junctions were preserved. When frozen-thawed ovaries were transplanted to the bursa of recipient hosts, pretreatment with collagenase significantly increased serum levels of AMH, the number of intact follicles and the total number of viable offspring compared to frozen-thawed ovaries without collagenase pretreatment, even 6 months after transplantation. Thus, the collagenase pretreatment could provide a beneficial approach for maintaining the functions and viability of cryopreserved ovaries in other species and clinically relevant situations.

Fertility Preservation for Pediatric and Adolescent Patients With Cancer: Medical and Ethical Considerations

Many cancers presenting in children and adolescents are curable with surgery, chemotherapy, and/or radiotherapy. Potential adverse consequences of treatment include sterility, infertility, or subfertility as a result of gonad removal, damage to germ cells as a result of adjuvant therapy, or damage to the pituitary and hypothalamus or uterus as a result of irradiation. In recent years, treatment of solid tumors and hematologic malignancies has been modified in an attempt to reduce damage to the gonadal axis. Simultaneously, advances in assisted reproductive technology have led to new possibilities for the prevention and treatment of infertility. This clinical report reviews the medical aspects and ethical considerations that arise when considering fertility preservation in pediatric and adolescent patients with cancer.

Germinal stage vitrification is superior to MII stage vitrification in prepubertal mouse oocytes

This study investigated if in vitro maturation (IVM) before or after vitrification would be more successful for prepubertal oocytes. To mimic prepubertal conditions in an experimental setup, oocytes were collected from healthy 14, 21 and 28day old Swiss albino mice. The germinal vesicle (GV) stage oocytes and in vitro matured MII oocytes were subjected to vitrification-warming. Both structural (meiotic spindle morphology, mitochondrial integrity, cortical granules) and functional (sperm zona binding, fertilization) characteristics were assessed in oocytes after warming. This study demonstrated that IVM was more detrimental to prepubertal oocytes than to young adults. Further, vitrification of the IVM oocytes resulted in an increase in the number of abnormal meiotic spindles, a change in the cortical distribution pattern, a reduction in sperm zona binding and the fertilization rate. Importantly, oocyte integrity was better when prepubertal oocytes were vitrified before, rather than after, IVM. The above observations support GV stage vitrification for prepubertal oocytes requiring fertility preservation. Understanding the mechanisms behind the differing outcomes for oocytes from immature females will help in refining current protocol, thereby retaining the oocytes' maximum structural and functional integrity Further investigation is necessary to determine whether human prepubertal oocytes also behave in a similar way. It is to be noted here, with great emphasis, that a major limitation of this study is that the oocytes' abilities were tested only until fertilisation, as a consequence of which the study cannot reveal the developmental potentials of the embryos beyond fertilisation.

Fertility preservation in BRCA mutation carriers-efficacy and safety issues: a review

BRCA mutation carriers face various situations that influence their fertility potential. There is still a lack of guideline or expert consensus on Fertility Preservation (FP) in BRCA mutation carriers and the necessity and safety of FP in BRCA mutation carriers is still in dispute. This review aims to focus on the population of BRCA mutation carriers by analyzing the existing FP strategies, comprehensively comparing the pros and cons of each strategy and its applicability.FP is a suggestion for BRCA mutation carriers with birth planning. Different FP strategies have different characteristics. Considering the particularity of BRCA mutation carriers, multiple factors need to be carefully considered. This review focuses on the applicability of each FP method for carriers under various circumstances. Available FP strategies including oocyte cryopreservation, ovarian tissue cryopreservation, preimplantation genetic diagnosis, and egg/embryo donation are analyzed by comparing existing methods comprehensively. In the attempt to provide an up-to-date decision-making guidance. Conditions taking into consideration were the carrier's age, the risk of breast and ovarian metastasis, plans for oncotherapy, FP outcome, time available for FP intervention and accessibility.Overall, FP is necessary and safe for BRCA mutation carriers. Among all available FP methods, oocyte cryopreservation is the most reliable procedure; ovarian tissue cryopreservation is the only way for preserving both fertility and endocrine function, recommended for pre-pubertal carriers and when time is limited for oocyte stimulation. A clear framework provides frontline clinical practitioners a new thought and eventually benefit thousands of BRCA mutation carriers.

Encapsulation of ovarian allograft precludes immune rejection and promotes restoration of endocrine function in immune-competent ovariectomized mice

Premature ovarian insufficiency (POI) is a significant complication of cytotoxic treatments due to extreme ovarian sensitivity to chemotherapy and radiation. POI is particularly devastating for young girls reaching puberty, because it irreversibly affects their physical and cognitive development. Changes occurring during puberty determine their height, bone health, insulin responsiveness, lipid metabolism, cardiovascular health and cognition. The only available treatment for POI during puberty is hormone replacement therapy (HRT), which delivers non-physiological levels of estrogen, lacks other ovarian hormones and pulsatility, and is not responsive to feedback regulation. Here we report that ovarian allografts encapsulated in a hydrogel-based capsule and implanted in ovariectomized mice restore ovarian endocrine function in immune competent mice. Ovarian tissue from BALB/c mice was encapsulated in poly(ethylene-glycol) (PEG) hydrogels, with a proteolytically degradable core and a non-degradable shell. The dual capsules were implanted subcutaneously in immune competent ovariectomized C57BL/6 mice for a period of 60 days. As expected, non-encapsulated ovarian allografts implanted in a control group sensitized the recipients as confirmed with donor-specific IgG in the serum, which increased 26-fold in the 3 weeks following transplantation (p = 0.02) and infiltration of the graft with CD8 T cells consistent with allo-immunity. In contrast, encapsulation in the Dual PEG capsules prevented sensitization to the allograft in all the recipients with no evidence of lymphocytic infiltration. In summary, the approach of hydrogel-based immunoisolation presents a minimally invasive and robust cell-therapy to restore hormonal balance in ovarian insufficiency. This report is the first to demonstrate the application of a tunable PEG-based hydrogel as an immunoisolator of allogeneic ovarian tissue to restore endocrine function in ovariectomized mice and prevent cell-mediated immune rejection in immune competent mice.

Preserving fertility in female patients with hematological malignancies: a multidisciplinary oncofertility approach

Oncofertility is a new interdisciplinary field at the intersection of oncology and reproductive medicine that expands fertility options for young cancer patients. The most common forms of hematological malignancies that occur in girls and young women and therefore necessitate oncofertility care are acute lymphocytic leukemia, acute myeloid leukemia, non-Hodgkin's lymphoma, and Hodgkin's lymphoma. Aggressive gonadotoxic anticancer regimens including alkylating chemotherapy and total body irradiation are used often in treating girls and young women with hematological malignancies. The risks of gonadotoxicity and subsequent iatrogenic premature ovarian insufficiency and fertility loss depend mainly on the type and stage of the disease, dose of anticancer therapy as well as the age of the patient at the beginning of treatment. To avoid or at least mitigate the devastating complications of anticancer therapy-induced gonadotoxicity, effective and comprehensive strategies that integrate different options for preserving and restoring fertility ranging from established to experimental strategies should be offered before, during, and after chemotherapy or radiotherapy. A multidisciplinary approach that involves strong coordination and collaboration between hemato-oncologists, gynecologists, reproductive biologists, research scientists, and patient navigators is essential to guarantee high standard of care.

Ovarian Tissue Transplantation: Experience From Germany and Worldwide Efficacy

Extraction of ovarian tissue prior to oncologic therapy and subsequent transplantation is being performed increasingly often to preserve fertility in women. The procedure can be performed at any time of the cycle and, therefore, generally does not lead to any delay in oncological therapy. Success rates with transplantation of cryopreserved ovarian tissue have reached promising levels. More than 130 live births have been reported worldwide with the aid of cryopreserved ovarian tissue and the estimated birth rate is currently approximately 30%. In Germany, Austria, and Switzerland, the FertiPROTEKT consortium has successfully achieved 21 pregnancies and 17 deliveries generated after 95 ovarian tissue transplantations by 2015, one of the largest case series worldwide confirming that ovarian tissue cryopreservation and transplantation are successful. Approximately, more than 400 ovarian tissue cryopreservation procedures are performed each year in the FertiPROTEKT consortium, and the request and operations for ovarian tissue transplantation have increased in recent years. Therefore, recommendations for managing transplantation of ovarian tissue to German-speaking reproductive medicine centers were developed. In this overview, these recommendations and our experience in ovarian tissue transplantation are presented and discussed with international procedures.

Chitosan Hydrogel Supports Integrity of Ovarian Follicles during In Vitro Culture: A Preliminary of A Novel Biomaterial for Three Dimensional Culture of Ovarian Follicles

Objective

Testing novel biomaterials for the three dimensional (3D) culture of ovarian follicles may ultimately lead to a culture model which can support the integrity of follicles during in vitro culture (IVC). The present study reports the first application of a chitosan (CS) hydrogel in culturing mouse preantral follicles.

Materials and Methods

In this interventional experiment study, CS hydrogels with the concentrations of 0.5, 1, and 1.5% were first tested for fourier transform infrared spectroscopy (FT-IR), Compressive Strength, viscosity, degradation, swelling ratio, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity and live/dead assay. Thereafter, mouse ovarian follicles were encapsulated in optimum concentration of CS (1%) and compared with those in alginate hydrogel. The follicular morphology, quality of matured oocyte and steroid secretion in both CS and alginate were assessed by enzyme-linked immunosorbent assay (ELISA). The expression of folliculogenesis, endocrine, and apoptotic related genes was also evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) and compared with day that in 0.

Results

The rates of survival, and diameter of the follicles, secretion of estradiol, normal appearance of meiotic spindle and chromosome alignment were all higher in CS group compared with those in alginate group (P≤0.05). The expression of Cyp19a1 and Lhcgr in CS group was significantly higher than that of the alginate group (P≤0.05).

Conclusion

The results showed that CS is a permissive hydrogel and has a beneficial effect on encapsulation of ovarian follicle and its further development during 3D culture.

What will the future hold for artificial organs in the service of assisted reproduction: prospects and considerations

Assisted reproduction provides a wide spectrum of treatments and strategies addressing infertility. However, distinct groups of infertile patients with unexplained infertility, congenital disorders, and other complex cases pose a challenge in in vitro fertilization (IVF) practices. This special cohort of patients is associated with futile attempts, IVF overuse, and dead ends in management. Cutting edge research on animal models introduced this concept, along with the development of artificial organs with the aim to mimic the respective physiological functions in reproduction. Extrapolation on clinical application leads to the future use of infertility management in humans. To date, the successful clinical application of artificial reproductive organs in humans is not feasible because further animal model studies are required prior to clinical trials. The application of these artificial organs could provide a solution to infertility cases with no other options. This manuscript presents an overview on the current status, future prospects, and considerations on the potential clinical application of artificial ovary, uterus, and gametes in humans. This paper presents how the IVF practice landscape may be shaped and challenged in the future, along with the subsequent concerns in assisted reproductive treatments.

Comparison between Slow Freezing and Vitrification for Human Ovarian Tissue Cryopreservation and Xenotransplantation

Two methods for the cryopreservation of human ovarian tissue were compared using a xenotransplantation model to establish a safe and effective cryopreservation method. Ovarian tissues were obtained from women who underwent benign ovarian surgery in the gynecology research unit of a university hospital. The tissues were transplanted into 112 ovariectomized female severe combined immunodeficient mice 4 weeks after slow freezing or vitrification cryopreservation. Tissues were retrieved 4 weeks later. Primordial follicular counts decreased after cryopreservation and xenotransplantation, and were significantly higher in the slow freezing group than in the vitrification group (p < 0.001). Immunohistochemistry and TUNEL assay showed that the Ki-67 and CD31 markers of follicular proliferation and angiogenesis were higher in the slow freezing group (p < 0.001 and p = 0.006, respectively) and DNA damage was greater in the vitrification group (p < 0.001). Western blotting showed that vitrification increased cellular apoptosis. Anti-Müllerian hormone expression was low in transplanted samples subjected to both cryopreservation techniques. Electron microscopy revealed primordial follicle deformation in the vitrification group. Slow freezing for ovarian tissue cryopreservation is superior to vitrification in terms of follicle survival and growth after xenotransplantation. These results will be useful for fertility preservation in female cancer patients.

Ovarian tissue cryopreservation: prospective randomized study on thawed ovarian tissue viability to estimate the maximum possible delivery time of tissue samples

Ovarian tissue cryopreservation is one of the most important methods to protect female fertility, but we just recently established the first central laboratory in China, now building a network with other hospitals. The aim was to estimate the thawed ovarian tissue viability and to explore the feasibility of short-distance transportation. Fifteen samples were obtained from each of 11 patients, i.e. in total 165 samples. One fresh sample was used for follicle counts, 14 punches were cryopreserved, thawed, and randomly divided into seven groups depending on the time after thawing: 0, 20, 40, 60, 80, 100, 120 min. Follicle counts, steroid hormones, and lactate levels were assessed. No significant differences for the three parameters of tissue viability comparing the seven groups were seen. The time can last up to two hours for the delivery of tissue samples from the laboratory to the surgery room. To our knowledge, this question has been tested for the first time systematically within a prospective randomized comparative study.

Negative air pressure treatment accelerates the penetration of permeable cryoprotectants into bovine ovarian tissue in vitrification protocol and improves cell density after vitrification

Effects of additional physical treatments during vitrification of the bovine ovarian tissue were examined for increasing of permeability of ethylene glycol (EG) and dimethyl sulfoxide (Me2SO). The concentrations of EG and Me2SO and histological changes in the ovarian tissue were evaluated. In the first equilibration step (7.5% EG and 7.5% Me2SO), all the 10-min physical treatments, i.e., negative (679 hPa) or positive (1347 hPa) air pressure applied with a disposable syringe, and shaking (60 rpm) applied with a laboratory shaker, were comparable to 25-min non-physical treatment (plain) vitrification. When effects of the negative air pressure were examined in the second equilibration step (20% EG and 20% Me2SO), its 10-min treatment was equivalent to 15-min plain vitrification (140-170 mg/g tissue). It was thus indicated that the negative air pressure treatment accelerates the penetration of permeable cryoprotectants into the ovarian tissue slices. Histological examination showed that the cell density and the amount of pan-cadherin in the tunica albuginea of the ovary was reduced by the vitrification, but was improved by the negative air pressure treatment. The amount of pan-cadherin in the tunica albuginea was recommended as a biomarker for evaluation of effectiveness of protocol for cryopreservation of bovine ovarian tissue and considered to be a candidate biomarker for human ovarian tissue cryopreservation.

Vitrification of canine ovarian tissues with polyvinylpyrrolidone preserves the survival and developmental capacity of primordial follicles

Ovarian tissue cryopreservation combined with immature follicle development can preserve female fertility in wildlife, regardless of age or reproductive timing. To investigate the effects of different cryopreservation methods and cryoprotectants on follicular survival and developmental capacity, ovarian cortical pieces from 15 dogs were cryopreserved by slow freezing or vitrification with different additional cryoprotectants as follows: dimethyl sulfoxide (DMSO), polyvinylpyrrolidone (PVP), combined DMSO and PVP (each at half the concentration of when used independently), or none (control). Cryopreserved ovarian tissues were evaluated by neutral red staining, histology, and xenotransplantation assays. Among cryopreservation conditions tested, vitrification with combined DMSO and PVP significantly improved the maintenance of follicular morphology compared to that in control. Furthermore, ovarian tissues vitrified using this condition maintained follicle morphology and developmental capacity 9 weeks after grafting, as shown by an increased percentage of primary and secondary follicles and a significant decrease in the transition stage from primordial to primary stage follicles 5 and 9 weeks after grafting. In contrast, slow freezing and control groups lost intact follicles by 5 weeks after grafting. The described cryopreservation techniques, which preserve canine follicle development, will build the foundation of ovarian tissue cryopreservation to preserve female fertility in wild canids.