Preliminary experience with subcutaneous human ovarian cortex transplantation in the NOD-SCID mouse

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.

Xenograft model of heterotopic transplantation of human ovarian cortical tissue and its clinical relevance

In brief

Xenografts of human ovarian cortical tissue provide a tractable model of heterotopic autotransplantation that is used for fertility preservation in patients undergoing ablative chemo/radiotherapy. This study describes the behavior of hundreds of xenografts to establish a framework for the clinical function of ovarian cortex following autotransplantation over short- and long-term intervals.

Abstract

More than 200 live births have been achieved using autotransplantation of cryopreserved ovarian cortical fragments, yet challenges remain to be addressed. Ischemia of grafted tissue undermines viability and longevity, typically requiring transplantation of multiple cortical pieces; and the dynamics of recruitment within a graft and the influence of parameters like size and patient age at the time of cryopreservation are not well-defined. Here, we describe results from a series of experiments in which we xenografted frozen/thawed human ovarian tissue (n = 440) from 28 girls and women (age range 32 weeks gestational age to 46 years, median 24.3 ± 4.6). Xenografts were recovered across a broad range of intervals (1-52 weeks post-transplantation) and examined histologically to quantify follicle density and distribution. The number of antral follicles in xenografted cortical fragments correlated positively with the total follicle number and was significantly reduced with increased patient age. Within xenografts, follicles were distributed in focal clusters, similar to the native ovary, but the presence of a leading antral follicle coincided with increased proliferation of surrounding follicles. These results underscore the importance of transplanting ovarian tissue with a high density of follicles and elucidate a potential paracrine influence of leading antral follicles on neighboring follicles of earlier stages. This temporal framework for interpreting the kinetics of follicle growth/mobilization may be useful in setting expectations and guiding the parameters of clinical autotransplantation.

Two-Decade Experience of Royan Institute in Obtaining Mature Oocyte from Cryopreserved Ovarian Tissue: In Vitro and In Vivo Approaches

Ovarian tissue cryopreservation (OTC) holds promise for preservation of fertility among women who have lost their fertility due to diseases such as cancer. OTC has significantly assisted such cases by helping them maintain normal hormonal levels and menstrual cycles. Appropriate strategies to develop and extract mature oocytes from OTC could overcome a range of complications that are associated with ovarian dysfunction, caused by aging, and primary or secondary ovarian insufficiency. Scientists from different departments at The Royan Institute (Tehran, Iran) have been conducting studies to find the best way to extract mature oocytes from animal and human cryopreserved ovarian tissues. The various studies conducted in this area in the past 20 years, by researchers of the Royan Institute, are collated and provided in this review, in order to provide an idea of where we are now in the area of fertility preservation.

Molecular Mechanism and Prevention Strategy of Chemotherapy- and Radiotherapy-Induced Ovarian Damage

Fertility preservation is an emerging discipline, which is of substantial clinical value in the care of young patients with cancer. Chemotherapy and radiation may induce ovarian damage in prepubertal girls and young women. Although many studies have explored the mechanisms implicated in ovarian toxicity during cancer treatment, its molecular pathophysiology is not fully understood. Chemotherapy may accelerate follicular apoptosis and follicle reservoir utilization and damage the ovarian stroma via multiple molecular reactions. Oxidative stress and the radiosensitivity of oocytes are the main causes of gonadal damage after radiation treatment. Fertility preservation options can be differentiated by patient age, desire for conception, treatment regimen, socioeconomic status, and treatment duration. This review will help highlight the importance of multidisciplinary oncofertility strategies for providing high-quality care to young female cancer patients.

Delaying Reproductive Aging by Ovarian Tissue Cryopreservation and Transplantation: Is it Prime Time?

Ovarian tissue cryopreservation and autotransplantation can restore ovarian endocrine function and fertility and recently were changed from experimental to fertility preservation procedures for medical indications by the American Society of Reproductive Medicine. Such advances have resulted in discussions around the utility of ovarian cryopreservation in healthy women to preserve fertility and delay menopause or as a hormone replacement approach. Such 'elective' use of ovarian tissue cryopreservation requires a risk-benefit assessment. Here, we review evidence for and against the utility of ovarian tissue harvesting in healthy women, scrutinize recent and needed advances to enhance the feasibility of such an approach, and provide practice and future research guidelines.

Is Ovarian Tissue Transport at Supra-zero Temperatures Compared to Body Temperature Optimal for Follicle Survival?

BACKGROUND/AIM

Transportation of ovarian cortex prior to freezing is used clinically; however, basic investigations of ovarian storage are limited and the question remains what temperature is optimal for transport over long distances and time periods. The aim of this study was to evaluate the rate of follicular loss over various time periods under two different temperatures and assess whether ovarian follicle viability is affected following cryopreservation and thawing subsequent to the transportation of ovarian tissue.

MATERIALS AND METHODS

Pig ovaries were transported at 4°C (n=10) or at 38°C (n=10) prior to cryopreservation. At 0, 4, 12 and 24 h tissues were fixed for histological examination and a LIVE/DEAD Assay. At the same time-points ovarian tissues were cryopreserved and analysed after thawing.

RESULTS

Histological evaluation and LIVE/DEAD Assay of freshly transported ovarian tissue showed significantly better follicle survival at 4°C during transportation duration. In cryopreserved ovarian tissues the LIVE/DEAD Assay showed a significant difference in the number of intact and dead follicles at 24 h in favor of 4°C (p<0.05).

CONCLUSION

Ovarian tissue transportation should be kept at a minimum to prevent potential damage.

Hormonal Stimulation of Human Ovarian Xenografts in Mice: Studying Folliculogenesis, Activation, and Oocyte Maturation

Ovarian tissue cryopreservation and banking provides a fertility preservation option for patients who cannot undergo oocyte retrieval; it is quickly becoming a critical component of assisted reproductive technology programs across the world. While the transplantation of cryopreserved ovarian tissue has resulted in over 130 live births, the field has ample room for technological improvements. Specifically, the functional timeline of grafted tissue and each patient's probability of achieving pregnancy is largely unpredictable due to patient-to-patient variability in ovarian reserve, lack of a reliable method for quantifying follicle numbers within tissue fragments, potential risk of reintroduction of cancer cells harbored in ovarian tissues, and an inability to control follicle activation rates. This review focuses on one of the most common physiological techniques used to study human ovarian tissue transplantation, xenotransplantation of human ovarian tissue to mice and endeavors to inform future studies by discussing the elements of the xenotransplantation model, challenges unique to the use of human ovarian tissue, and novel tissue engineering techniques currently under investigation.

Slow-Freezing Cryopreservation Ensures High Ovarian Tissue Quality Followed by In Vivo and In Vitro Methods and Is Safe for Fertility Preservation

Background and objectives: Cancer incidence is growing with younger patients diagnosed with this disease every year. Improved cancer diagnostics and treatment lead to better survival of cancer patients. However, after aggressive chemo- or radiotherapy, cancer survivors suffer from various degrees of subfertility or infertility. Several fertility preservation technologies have been developed for young cancer patients: cryopreservation of germ cells, embryos, or reproductive tissues. The best results have been shown by cryopreservation of sperm and embryos. Yet the success of using cryopreserved oocytes or reproductive tissues (ovarian and testicular) is still insufficient. Therefore, this study was designed to assess the vitality, viability, general quality, and safety of frozen-thawed human ovarian tissue for retransplantation using modern molecular tests. Materials and Methods: The new miRNA array test was used to evaluate miRNA expression in thawed ovarian tissue in combination with standard xenotransplantation and pathological examination of microslides. Results: Our results demonstrated that slow freezing is an efficient way (80%) to cryopreserve ovarian tissue with no structural damage afterwards. We have shown that xenotransplantation into immunodeficient mice, histology, and immunohistochemistry could be potentially replaced by more recent molecular methods. Conclusions: The latter method has shown that altered expression of miRNAs might be used as identifiers of normal/damaged tissue after further analysis. Newer, safer, and more specific approaches need to be developed in order to eliminate the risk of disease reoccurrence.

Two base pair deletion in IL2 receptor γ gene in NOD/SCID mice induces a highly severe immunodeficiency

Genome editing has recently emerged as a powerful tool for generating mutant mice. Small deletions of nucleotides in the target genes are frequently found in CRISPR/Cas9 mediated mutant mice. However, there are very few reports analyzing the phenotypes in small deleted mutant mice generated by CRISPR/Cas9. In this study, we generated a mutant by microinjecting sgRNAs targeting the IL2 receptor γ gene and Cas9 protein, into the cytoplasm of IVF-derived NOD.CB17/Prkdcscid/JKrb (NOD/SCID) mice embryos, and further investigated whether a 2 bp deletion of the IL2 receptor γ gene affects severe deficiency of immune cells as seen in NOD/LtSz-scid IL2 receptor γ^−/− (NSG) mice. Our results show that the thymus weight of mutant mice is significantly less than that of NOD/SCID mice, whereas the spleen weight was marginally less. T and B cells in the mutant mice were severely deficient, and NK cells were almost absent. In addition, tumor growth was exceedingly increased in the mutant mice transplanted with HepG2, Raji and A549 cells, but not in nude and NOD/SCID mice. These results suggest that the NOD/SCID mice with deletion of 2 bp in the IL2 receptor γ gene shows same phenotype as NSG mice. Taken together, our data indicates that small deletions by genome editing is sufficient to generate null mutant mice.

Investigation on revascularization time and initial damage after transplantation of fresh and cryopreserved ovarian tissue in domestic cats

The present study evaluated revascularization time of fresh and cryopreserved cat ovarian tissue after transplantation to subcutaneous tissue. Ovaries of five cats were used and eight pieces of ovarian tissue were taken from each pair of ovaries. Immediately after removal, three pieces were transplanted and one fixed for fresh control. The remaining four pieces were cryopreserved and, after thawing, one was fixed for cryopreservation control and three were transplanted. Grafts were recovered on days 2 (D2), 4 (D4) and 6 (D6) post-transplantation. Blood vessels were identified by immunohistochemistry and doppler ultrasound. Immunohistochemistry showed that the percentages of total tissue area occupied by blood vessels were similar (P > 0.05) in fresh and cryopreserved tissues. In both cases, blood vessel area was significantly higher (P < 0.05) on D4 and D6 compared to D0. Ultrasound analysis showed vascularization improvement on the periphery of grafts from D2 to D4 and from D4 to D6, both in fresh and cryopreserved tissue samples. Nonetheless, there was a significant decrease (P < 0.05) in the percentage of morphologically normal follicles (MNF) after transplantation compared to non-transplanted tissue (D0), both for fresh and cryopreserved samples. Moreover, the number of follicles found in samples was considerably smaller after grafting. In conclusion, revascularization of ovarian tissue autotransplanted to subcutaneous tissue in domestic cats occurs within 4 days after transplantation, both for fresh and cryopreserved tissue. However, large follicular loss has been observed in the first days post-transplantation, especially in cryopreserved tissues.

Ovarian tissue vitrification is more efficient than slow freezing to preserve ovarian stem cells in CF-1 mice

OBJECTIVE

The aim of this study was to investigate the efficacy of protocols for mice ovary cryopreservation to compare the differences in Mouse Vasa Homologue expression (a germline cell marker) and ovarian viability after vitrification or slow freezing.

METHODS

Female CF1 mice aged 40-45 days were randomly divided into three groups: Control, vitrification or slow freezing. Their ovaries were surgically removed, rinsed in saline solution and cryopreserved. For vitrification, we used a commercial protocol and for slow freeze, we used 1.5 M ethylene glycol (EG) as cryoprotectant. After that, the ovaries were processed for histological an immunohistochemical analysis, and counting of primordial, primary, pre-antral and antral follicles.

RESULTS

No significant difference was found in the proportion of high-quality primordial, primary and pre-antral follicles after thawing/warming in the slow freezing and vitrification groups. The immunohistochemistry for MVH antibody demonstrated that the slow freeze group had a higher number of unmarked cells (p=0.012), indicating a harmful effect on the MVH expression in the ovarian tissue, where the cell structure is complex.

CONCLUSION

Although both protocols indicated similar results in the histological analysis of follicular counts, the vitrification protocol was significantly better to preserve ovarian stem cells, an immature germ cell population. These cells are able to self-renew having regeneration potential, and may be effective for the treatment of ovarian failure and consequently infertility.

Influence of graft size, histocompatibility,and cryopreservation on reproductive outcome following ovary transplantation in mice

Purpose

Transplantation of ovarian tissue is a valuable method to rescue mouse strains with fertility problems and to revitalize archived strains. The purpose of this study was to investigate the effect of (i) different sizes of transplanted ovary pieces on reproductive outcome, (ii) use of immunodeficient recipients to overcome the limitation of histocompatibility, and (iii) to compare different protocols for cryopreservation of ovarian tissue.

Methods

Halves, quarters, and eights of mouse ovaries were transplanted. Half ovaries from B6 donors were transferred into immunodeficient mice. Halves of ovaries were frozen according to four different protocols, thawed and transferred.

Results

Pregnancy rate after transplantation of ovarian tissue was high (90–100%) independent of the transplant size. Although, the average litter size was significantly lower for recipients of quarters and eights (4.4 and 4.6 vs. 6.5), the total number of offspring produced per donor ovary was higher compared with recipients of halves. Pregnancy rate of immunodeficient recipients was 40% (mean 4.7 offspring per litter). All four cryopreservation protocols used were able to preserve functionality of the ovarian tissue.

Conclusions

Transplantation of ovarian tissue smaller than halves resulted in reduced litter sizes. The distribution of ovarian tissue of one donor female to 4 or 8 recipients will therefore yield in a higher total number of offspring in a certain time period. The use of immunodeficient recipients is an option for non-histocompatible donors. Cryopreservation of ovarian tissue is generally feasible but the function of frozen-thawed ovary halves after transplantation differs depending on the freezing protocol used.

Current state and future possibilities of ovarian tissue transplantation

BACKGROUND

As a result of recent developments in cancer treatment, cancer survivorship and survivors' quality of life have been emphasized. Although ovarian tissue cryopreservation (OTC) is an experimental technique, it would be the sole technique for fertility preservation treatment for girls with malignant disease. Indeed, OTC requires ovarian tissue transplantation (OTT) for conception. As for OTC, there is room to investigate OTT. The present review focused on the current state and progress of OTT.

METHOD

The literature regarding OTT, which is currently under development, was reviewed.

MAIN FINDINGS

To improve the outcome of OTT, both efficacy and safety are important. Good surgical technique and the optimal site are important surgical factors, with orthotopic transplantation increasing. Treatment of growth factors, gonadotropins, antioxidants, apoptosis suppression factors, and cell therapy may improve the efficacy of OTT by inducing neo-angiogenesis and preventing damage. Artificial ovaries, complete in vitro primordial follicle culture technique, and non-invasive ovarian imaging techniques, such as optical coherence tomography, to select the best ovarian tissue are future possibilities.

CONCLUSION

Improving neo-angiogenesis and preventing damage with optimization, as well as investigation of future techniques, may bring us to the next stage of a fertility preservation strategy.

Repetitive Maturation of Oocytes From Non-Stimulated Xenografted Ovarian Tissue From a Prepubertal Patient Indicating the Independence of Human Ovarian Tissue

Introduction

Modern anti-cancer strategies have distinctly increased survival rates; nevertheless, often accompanied by sterility. Currently, the only option for preserving fertility in prepubertal females is to cryopreserve ovarian tissue and re-transplant frozen-thawed tissue to restore fertility after treatment. Our aim was to report the occurrence of repetitive antral follicle formation and oocyte maturation in a prepubescent ovarian tissue xenograft without exogenous hormone stimulation.

Material and Methods

Frozen-thawed ovarian tissue from a 6-year-old patient suffering from nephroblastoma was xenotransplanted in oophorectomized severe combined immunodeficiency (SCID) mice to evaluate follicle development.

Ergebnisse

Repetitive follicle development to the antral stage occurred in the same xenograft of prepubertal ovarian tissue without exogenous hormone administration; 37 days after retrieving a maturing oocyte (this first retrieval has been previously published), another, completely mature oocyte was harvested from the xenograft. Subsequent histological evaluation of the grafted tissue showed primordial follicles, nearly all stages of developing follicles, as well as large atretic ones. Many clusters with dormant primordial follicles were also present.

Conclusion

Xenotransplanted prepubertal ovarian tissue has the potential for repetitive oocyte retrieval cycles without administering exogenous hormones. The results indicate that the human ovarian tissue might be able to synchronize the hypothalamus-hypophysis-axes of the mouse to the physiological human cycle; this should be investigated in future studies.

Comparison of Allotransplantation of Fresh and Vitrified Mouse Ovaries to The Testicular Tissue under Influence of The Static Magnetic Field

Objective

The aim of this study was to investigate the effects of static magnetic field (SMF) during transplantation of the ovarian tissue into the testis.

Materials and Methods

In this experimental study, ovaries of 6- to 8-week-old female Naval Medical Research Institute (NMRI) mice were randomly divided into four groups: i. Fresh ovaries were immediately transplanted into the testicular tissue (FOT group), ii. Fresh ovaries were exposed to the SMF for 10 minutes and then transplanted into the testicular tissue (FOT+group), iii. Vitrified-warmed ovaries were transplanted into the testicular tissue (VOT group), and iv. Vitrified-warmed ovaries were transplanted into the testicular tissue and the transplantation site was then exposed to the SMF for 10 minutes (VOT+group).

Results

The lowest percentages of morphologically dead primordial follicles and the highest percentages of morphologically intact primordial follicles were seen in the FOT+ group (4.11% ± 2.88 and 41.26% ± 0.54, respectively). Although the lowest significant percentage of maturation, embryonic development and fertility was observed in the VOT group as compared to the other groups, the difference in the fertility rate was not significant between the VOT and VOT+groups. Estrogen and progesterone concentrations were significantly higher in the FOT+group than those of the control mice.

Conclusion

It is concluded that, exposure of the vitrified-warmed ovaries to SMF retains the structure of the graft similar to that of fresh ovaries.

Human umbilical cord stem cell conditioned medium versus serum-free culture medium in the treatment of cryopreserved human ovarian tissues in in-vitro culture: a randomized controlled trial

BACKGROUND

To reduce young female fertility loss, the in-vitro culture of cryopreserved ovarian cortical tissues (OCTs) is considered an effective approach without delaying treatment and undergoing stimulation medicine. However, ischemic damage and follicular loss during the in-vitro culture of OCTs are major technical challenges. Human umbilical cord stem cells (HUMSCs) and their conditioned medium (HUMSC-CM) have been considered to be potential resources for regeneration medicine because they secrete cytokines and enhance cell survival and function. The aim of this study was to determine whether HUMSC-CM improves the development of frozen-thawed in-vitro cultured ovarian tissues compared with a serum-free culture medium (SF-CM).

METHODS

The thawed OCTs (n = 68) were cultivated in HUMSC-CM and SF-CM in vitro for 8 days, and the ovarian tissues were processed and analyzed by a classical histological evaluation. The microvessel density (MVD) and apotosis detection during in-vitro culture of OCTs were also performed.

RESULTS

A significant difference in the rate of morphologically normal primordial follicles in the HUMSC-CM group was observed compared to that in the SF-CM group (group C) from days 2 to 4 (day 2: group B 58.0 ± 2.45% vs group C 32.0 ± 5.83%, p = 0.002; day 3: group B 55.5 ± 4.20% vs group C 21.0 ± 9.80%, p = 0.048; day 4: group B 52.0 ± 4.08% vs group C 21.5 ± 8.19%, p = 0.019). The microvessel density (MVD) detection showed a time-dependent increase and peaked on day 4. There was a significant difference between groups B (49.33 ± 0.58) and C (24.33 ± 3.79) (p = 0.036). The percentage of apoptotic follicles in group B was lower than that in group C on day 1 (13.75 ± 2.50% vs 27.0 ± 10.10%, p = 0.003), day 5 (11.75 ± 1.50% vs 51.0 ± 10.5%, p = 0.019) and day 7 (15.0 ± 5.10% vs 46.5 ± 21.75%, p = 0.018).

CONCLUSIONS

These data have provided the first experimental evidence of the effect of HUMSC-CM on frozen-thawed OCTs in vitro. The results showed that the HUMSC-CM group provided a better protecting effect on the in-vitro culture of the cryopreserved OCTs compared to the SF-CM group.

Cryopreservation and xenografting of human ovarian fragments: medulla decreases the phosphatidylserine translocation rate

BACKGROUND

Phosphatidylserine is the phospholipid component which plays a key role in cell cycle signaling, specifically in regards to necrosis and apoptosis. When a cell affected by some negative factors, phosphatidylserine is no longer restricted to the intracellular side of membrane and can be translocated to the extracellular surface of the cell. Cryopreservation can induce translocation of phosphatidylserine in response to hypoxia, increasing intracellular Ca²⁺, osmotic disruption of cellular membranes, generation of reactive oxygen species and lipid peroxidation. As such the aim of this study was to test the level of phosphatidylserine translocation in frozen human medulla-contained and medulla-free ovarian tissue fragments.

METHODS

Ovarian fragments from twelve patients were divided into small pieces of two types, medulla-free cortex (Group 1, n = 42, 1.5-3.0 × 1.5-3.0 × 0.5-0.8 mm) and cortex with medulla (Group 2, n = 42, 1.5-3.0 × 1.5-3.0 × 1.5-2.0 mm), pre-cooled after operative removal to 5 °C for 24 h and then conventionally frozen with 6 % dimethyl sulfoxide, 6 % ethylene glycol and 0.15 M sucrose in standard 5-ml cryo-vials. After thawing at +100 °C and step-wise removal of cryoprotectants in 0.5 M sucrose, ovarian pieces were xenografted to SCID mice for 45 days. The efficacy of tissues cryopreservation, taking into account the presence or absence of medulla, was evaluated by the development of follicles (histology with hematoxylin-eosin) and through the intensity of translocation of phosphatidylserine (FACS with FITC-Annexin V and Propidium Iodide).

RESULTS

For Groups 1 and 2, the mean densities of follicles per 1 mm³ were 9.8, and 9.0, respectively. In these groups, 90 and 90 % preantral follicles appeared morphologically normal. However, FACS analysis showed a significantly decreased intensity of translocation of phosphatidylserine (FITC-Annexin V positive) after cryopreservation of tissue with medulla (Group 2, 59.6 %), in contrast with tissue frozen without medulla (Group 1, 78.0 %, P < 0.05). In Groups 1 and 2 it was detected that 21.6 and 40.0 % cells were viable (FITC-Annexin V negative, Propidium Iodide negative).

CONCLUSION

The presence of medulla in ovarian pieces is beneficial for post-thaw development of cryopreserved human ovarian tissue.

Contribution of in vitro systems to preservation and utilization of porcine genetic resources

Historically, the conservation or preservation of mammalian genetic resources, especially farm animals, has been conducted under in situ conditions by maintaining living individuals as "livestock." However, systems for laboratory in vitro embryo production using gametes such as spermatozoa and oocytes are now available, in addition to ex situ preservation methods for mammalian genetic resources. One of these methods is the cryopreservation of gametes, embryos, and gonadal tissues. In pigs, freezing of sperm is the most reliable and well-established method for this purpose. On the other hand, cryopreservation of female gametes (oocytes) and gonadal tissues-usually by vitrification-has been associated with very low efficacies. Recently, in our laboratory, some research themes related to this issue have been pursued. We have been focusing on advances in porcine in vitro embryo production systems, and here, we introduce recent data on the vitrification of porcine immature oocytes and gonadal tissues followed by their xenografting into host mice to produce gametes.

Ethical aspects of creating human-nonhuman chimeras capable of human gamete production and human pregnancy

In this paper I explore some of the moral issues that could emerge from the creation of human-nonhuman chimeras (HNH-chimeras) capable of human gamete production and human pregnancy. First I explore whether there is a cogent argument against the creation of HNH-chimeras that could produce human gametes. I conclude that so far there is none, and that in fact there is at least one good moral reason for producing such types of creatures. Afterwards I explore some of the moral problems that could emerge from the fact that a HNH-chimera could become pregnant with a human conceptus. I focus on two sets of problems: problems that would arise by virtue of the fact that a human is gestated by a nonhuman creature, and problems that would emerge from the fact that such pregnancies could affect the health of the HNH-chimera.

Follicle Development of Xenotransplanted Sheep Ovarian Tissue into Male and Female Immunodeficient Rats

Background

This study aimed to assess follicle survival after xenotransplantation of sheep ovarian tissue into male and female immunodeficient rats. We evaluated the effects of gonadotropin treatment on follicular development in the transplanted tissue.

Materials and Methods

In this experimental study, sheep ovarian cortical strips were transplanted into the neck back muscles of 8 male and 8 female immunodeficient, castrated rats. Fourteen days after surgery, each rat was treated with human menopausal gonadotropin (hMG) for 9 weeks. One day after the last injection, ovarian tissues were removed and fixed for histology assessment. Histology analyses were performed before and after grafting. Estradiol (E₂) levels were measured before and after gonadectomy, and at the end of the experiment. The control group consisted of 7 male and 7 female noncastrated/non-grafted rats and the sham group comprised 7 male and 7 female castrated/ non-grafted rats for comparison of serum E₂ concentrations.

Results

The percentage of primordial follicles decreased after transplantation in male (25.97%) and female (24.14%) rats compared to the control group (ovarian tissue nongrafted; 37.51%). Preantral follicles increased in the male (19.5%) and female (19.49%) transplanted rats compared to the control group (11.4%). Differences in antral follicles between male (0.06 ± 0.0%) and female (0.06 ± 0.0%) rats were not noticeable compared to control (1.25 ± 0.0%) rats. We observed a significantly higher percent of mean E₂ secretion in grafted males compared to grafted females (P˂0.05).

Conclusion

Despite significant differences in E₂ secretion between xenografted male and female rats, we observed no statistical differences in terms of follicular development.

Effects of L-carnitine on follicular survival and graft function following autotransplantation of cryopreserved-thawed ovarian tissues

The aim of this study was to investigate the effects of L-carnitine (LC) on follicular survival and ovarian function following cryopreservation-thawing and autotransplantation of ovarian tissues. ICR mice were divided into three groups: control; saline group (cryopreservation+autograft+saline); and LC group (cryopreservation+autograft+L-carnitine). The ovarian tissues from control group, saline group, and LC group were histological assessed. There were no significant differences in the percentage of morphologically normal primordial follicles between the LC group and the saline group. After 28 days of autotransplantation, apoptosis rates, plasma malondialdehyde (MDA), progesterone (P4) and estradiol (E2) concentrations, and follicular densities of grafts were evaluated. Apoptosis rate and the concentration of MDA in the LC group were significantly lower than those in the saline group. The concentration of E2 and follicular densities of grafts in LC group were significantly higher than that in saline group. LC inhibits follicle apoptosis and increases follicular survival and function of ovarian graft.

Effect of antifreeze protein on mouse ovarian tissue cryopreservation and transplantation

PURPOSE

To investigate the effect of antifreeze protein (AFP) supplementation on ovarian vitrification and transplantation.

MATERIALS AND METHODS

In this experimental study, we researched a total of 182 ovaries from 4-week-old ICR mice. The equilibration solution included 20% ethylene glycol (EG), and the vitrification solution included 40% EG, 18% Ficoll, and 0.3 M sucrose. Intact ovaries were first suspended in 1 mL of equilibration solution for 10 min, and then mixed with 0.5 mL of vitrification solution for 5 min. Ovaries were randomly assigned to 3 groups and 0, 5, or 20 mg/mL of type III AFP was added into the vitrification solution (control, AFP5, and AFP20 groups, respectively). The vitrified ovaries were evaluated after warming and 2 weeks after autotransplantation. The main outcome measurements are follicular morphology and apoptosis assessed by histology and the TUNEL assay.

RESULTS

A significantly higher intact follicle ratio was shown in the AFP treated groups (control, 28.9%; AFP5, 42.3%; and AFP20, 44.7%). The rate of apoptotic follicles was significantly lower in the AFP treated groups (control, 26.6%; AFP5, 18.7%; and AFP20, 12.6%). After transplantation of the vitrified-warmed ovaries, a significantly higher intact follicle ratio was shown in the AFP20 group. The rate of apoptotic follicles was similar among the groups.

CONCLUSION

The results of the present study suggest that supplementing AFP in the vitrification solution has beneficial effects on the survival of ovarian tissue during cryopreservation and transplantation.

Xenotransplantation of cryopreserved human ovarian tissue--a systematic review of MII oocyte maturation and discussion of it as a realistic option for restoring fertility after cancer treatment

OBJECTIVE

To systematically review the reporting of MII (MII) oocyte development after xenotransplantation of human ovarian tissue.

DESIGN

Systematic review in accordance with the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA).

SETTING

Not applicable.

PATIENT(S)

Not applicable.

INTERVENTION(S)

Formation of MII oocytes after xenotransplantation of human ovarian tissue.

MAIN OUTCOME MEASURE(S)

Any outcome reported in Pubmed.

RESULT(S)

Six publications were identified that report on formation of MII oocytes after xenotransplantation of human ovarian tissue.

CONCLUSION(S)

Xenografting of human ovarian tissue has proved to be a useful model for examining ovarian function and follicle development in vivo. With human follicles that have matured through xenografting, the possibility of cancer transmission and relapse can also be eliminated, because cancer cells are not able to penetrate the zona pellucida. The reported studies have demonstrated that xenografted ovarian tissue from a range of species, including humans, can produce antral follicles that contain mature (MII) oocytes, and it has been shown that mice oocytes have the potential to give rise to live young. Although some ethical questions remain unresolved, xenotransplantation may be a promising method for restoring fertility. This review furthermore describes the value of xenotransplantation as a tool in reproductive biology and discusses the ethical and potential safety issues regarding ovarian tissue xenotransplantation as a means of recovering fertility.

Influence of mouse strain on ovarian tissue recovery after engraftment with angiogenic factor

Background

For women facing gonadotoxic treatment, cryopreservation of ovarian tissue with subsequent retransplantation during remission is a promising technique for fertility preservation. However, follicle loss within grafted ovarian tissue can be caused by ischemia and progressive revascularization. Several xenograft models using different immunodeficient rodent lines are suitable for studying ovarian tissue survival and follicular viability after frozen-thawed ovarian cortex transplantation. SCID mice, which are deficient for functional B and T cells, are the most commonly used mice for ovarian xenograft studies. However, due to incomplete immunosuppression, NOD-SCID mice displaying low NK cell function and an absence of circulating complement might be more appropriate. The present study aims to define the most appropriate immunodeficient mouse strain for ovarian tissue xenotransplantation by comparing ovarian graft recovery in SCID and NOD-SCID mice following engraftment in the presence of isoform 111 of vascular endothelial growth factor.

Methods

Sheep ovarian cortex fragments were embedded in a collagen matrix, with or without VEGF₁₁₁, before being stitched onto the ovaries of SCID and NOD-SCID mice. Transplants were recovered after 3 days to study early revascularization or after 3 weeks to evaluate follicle preservation and tissue fibrosis through histological analyses.

Results

At day 3, vessels were largely reorganized in the ovarian grafts of both mouse strains. After 3 weeks, the cortical tissue was clearly identifiable in SCID mice but not in NOD-SCID mice. Upon VEGF₁₁₁ treatment, vascularization was significantly improved 3 days after transplantation in SCID mice. This increase in vessel density was correlated with better follicular preservation in SCID mice 3 weeks after transplantation. Fibrosis was not decreased by VEGF treatment in either mouse strain.

Conclusions

Tissue architecture and follicular morphology were better preserved in ovarian tissues grafted in SCID mice in comparison with NOD-SCID mice. Moreover, tissue revascularization was improved in SCID mice by VEGF₁₁₁ graft treatment. Thus, we consider SCID mice to be the best murine model for studying ovarian tissue xenografts.

Ovarian blood vessel occlusion as a surgical sterilization method in rats

PURPOSE

To evaluate the female sterilization by occlusion of the ovarian blood flow, using the rat as experimental model.

METHODS

Fifty-five females rats were divided into four groups: I (n=10), bilateral ovariectomy, euthanized at 60 or 90 days; II (n=5), opening the abdominal cavity, euthanized at 90 days; III (n=20), bilateral occlusion of the ovarian blood supply using titanium clips, euthanized at 60 or 90 days; and IV (n=20), bilateral occlusion of the ovarian blood supply using nylon thread, euthanized at 60 or 90 days. The estrous cycle was monitored by vaginal cytology. After euthanasia, the reproductive tissues were evaluated histologically.

RESULTS

Ovarian atresia was identified macroscopically at 60 days after surgery in the rats in groups III and IV; however, most of the rats in group III maintained cyclicity. Histology of the tissues from group IV revealed that the ovarian tissue was replaced by dense fibrous connective tissue that was slightly vascularized and that intact follicles were absent by 90 days.

CONCLUSION

Ovarian blood vessels occluded caused ischemia, leading to progressive tissue necrosis, and bilateral occlusion using a nylon ligature is a viable method for surgical sterilization.

Effect of necrostatin on mouse ovarian cryopreservation and transplantation

OBJECTIVE

To investigate the effects of necrostatin-1 (Nec-1) supplementation on vitrification, warming and transplantation of ovarian tissue.

STUDY DESIGN

Ovaries from 4-week-old ICR mice were vitrified using a two-step procedure; ovaries were suspended in equilibration solution for 10min, and then mixed with vitrification solution for 5min. Ovaries were divided at random into three groups and 0 (control), 25 or 100μM Nec-1 was added to the vitrification solution. After warming, follicular morphology and apoptosis were assessed. For each group, a sample of vitrified, warmed ovaries was autotransplanted. The same dose of Nec-1 that was added to the vitrification solution was added to each warming solution and injected intraperitoneally. Follicular morphology and apoptosis of transplanted ovaries were assessed after 2 weeks.

RESULTS

After vitrification and warming, morphological analysis revealed that the intact follicle ratio was significantly higher in the Nec-1-treated groups compared with the control group (control, 45.1%; 25μM Nec-1, 51.7%; 100μM Nec-1, 57.9%). The rate of apoptosis was lower in the Nec-1 treated groups compared with the control group (control, 11.2%; 25μM Nec-1, 8.5%; 100μM Nec-1, 7.2%). After transplantation of the vitrified, warmed ovaries, morphological analysis revealed that the intact follicle ratio was significantly higher in the Nec-1 treated groups compared with the control group (control, 43.1%; 25μM Nec-1, 60.6%; 100μM Nec-1, 70.7%). The rate of apoptosis was lower in the Nec-1 treated groups compared with the control group (control, 5.3%; 25μM Nec-1, 2.5%; 100μM Nec-1, 2.0%).

CONCLUSIONS

Nec-1 supplementation during vitrification, warming and transplantation has beneficial effects on the survival of ovarian tissue. These results can help to improve ovarian tissue vitrification and transplantation protocols for fertility preservation.

Whole ovine ovaries as a model for human: perfusion with cryoprotectants in vivo and in vitro

These experiments were performed to test the perfusion of ovine as a model for human ovaries by cryoprotectants in vivo at high temperature when the permeability of capillaries is high and when blood is insensibly replaced by the solution of cryoprotectants. By our hypothetical supposition, ovaries could be saturated by cryoprotectants before their surgical removal. The objective was to examine the effectiveness of perfusion of ovine ovaries with vascular pedicle in vivo and in vitro. Arteria ovarica was cannuled and ovaries were perfused by Leibovitz L-15 medium + 100 IU/mL heparin + 5% bovine calf serum + 6% dimethyl sulfoxide + 6% ethylene glycol + 0.15 M sucrose + Indian ink in vivo and in vitro. In the first and second cycle of experiments, ovaries (n = 13 and n = 23) were perfused in vivo and in vitro, respectively, during 60 min with the rate of perfusion 50 mL/h (0.8 mL/min). It was established with in vivo perfusion that only about 10% of ovarian tissues were perfused due to an appearance of multiple anastomoses when the perfusion medium goes from arteria ovarica to arteria uterina without inflow into the ovaries. It was concluded that in vitro perfusion of ovine intact ovaries with vascular pedicle by freezing medium is more effective than this manipulation performed in vivo.

Fertility preservation and minimizing reproductive damage in cancer survivors

Recent advances in oncology have helped in the survival and cure of increasing numbers of childhood cancer patients and those during their reproductive age period. This has increased the need to improve existing technology, and prompted the search for new technologies, to minimize the gonadotoxic effects of cancer treatment and preserve human fertility. Conservative surgical approaches for cancer treatment have been widely accepted following progress in early detection of cancer and accumulating long-term outcome safety data. Gonadal suppression to increase resistance to cancer treatment by gonadotropin analogues and sex hormones has been suggested. However, while this is unlikely to be effective in males, there is no general consensus on its success in the female. Fertility preservation options for both male and female patients include cryopreservation of embryos, gametes and gonads. While embryo cryopreservation is a well-established and successful technique, there are several obvious limitations. Gamete cryopreservation is very successful in males (sperm freezing) while still experimental in females (oocyte freezing), with growing evidence suggesting its potential success. Gonadal cryopreservation is still in its early stages of experimental development, both in males (testicular tissue cryopreservation and in vitro spermatogenesis) and female (ovarian tissue cryopreservation and in vitro follicular maturation).

Quality and functionality of human ovarian tissue after cryopreservation using an original slow freezing procedure

PURPOSE

To evaluate the efficiency of an original slow freezing protocol on the quality and function of human ovarian cortex.

METHODS

Human ovarian tissues were cryopreserved using a freezing medium supplemented with propanediol and raffinose as cryoprotectants and antioxidants (L-glutamine, taurine). Samples were then frozen using a faster cooling rate than the usual one. Viability and morphology of follicles, DNA fragmentation in follicles and stroma as well as histology of the vascular endothelium were analyzed before and after freezing/thawing. Moreover, a functional analysis was performed based on the evaluation of follicular growth and development in thawed ovarian tissues that were cultured in vitro.

RESULTS

Our freezing/thawing protocol allows preservation of a high proportion of viable follicles and the preservation of the different follicle developmental stages (p>0.05 versus fresh control). 70.5 ± 5.2 % of follicles retained an intact morphology after cryopreservation (p=0.04). Stroma cells but not follicles exhibited a slight increase of DNA fragmentation after thawing (p<0.05). Microvessel endothelium within thawed tissues appeared to be preserved. Granulosa cells showed signs of proliferation in follicles cultured for 12 days. Secretion of 17β-oestradiol significantly increased during in vitro culture.

CONCLUSIONS

This protocol leads to good preservation of ovarian integrity and functionality post-thawing and thus appears as a suitable technique of ovarian tissue cryopreservation in clinical settings. Further research could be extended to optimize conditions of in vitro culture.

Cryopreservation of Ovarian Tissue: Detailed Description of Methods for Transport, Freezing and Thawing

Purpose: In many cases cancer therapy leads to an irreversible reduction or even loss of ovarian reserve. Cryopreservation of ovarian tissue with subsequent thawing and re-transplantation of tissue after the cancer is in remission constitutes a promising method to preserve fertility in women. To date, more than 25 cases of live births after re-transplantation of cryopreserved ovarian tissue have been published worldwide. In Germany the first live birth after re-transplantation of cryopreserved tissue was in 2011. Material and Methods: After surgical removal of ovarian tissue in the Gynaecological Clinic of Dresden University, the tissue was sent to the Gynaecological Clinic of Bonn University in a special transport container at 5 °C and was frozen the next day using 1.5 M dimethyl sulfoxide cryosolution. In 2010 this ovarian tissue was thawed using a sucrose solution in the Gynaecological Clinic of Erlangen University Clinical Centre and was laparoscopically re-transplanted into the patient. Results: The patient became pregnant, the pregnancy was uneventful, and she gave birth to a healthy boy. Conclusion: Freezing of ovarian tissue with subsequent re-transplantation as described here is a viable method to preserve fertility in cancer patients.

Host platelets and, in part, neutrophils mediate lung accumulation of transfused UVB-irradiated human platelets in a mouse model of acute lung injury

We previously reported that ultraviolet light B (UVB)-treated human platelets (hPLTs) can cause acute lung injury (ALI) in a two-event SCID mouse model in which the predisposing event was Lipopolysaccharide (LPS) injection and the second event was infusion of UVB-treated hPLTs. To delineate contributions of host mouse platelets (mPLTs) and neutrophils in the pathogenesis of ALI in this mouse model, we depleted mPLTs or neutrophils and measured hPLT accumulation in the lung. We also assessed lung injury by protein content in bronchoalveolar lavage fluid (BALF). LPS injection followed by infusion of UVB-treated hPLTs resulted in sequestration of both mPLTs and hPLTs in the lungs of SCID mice, although the numbers of neutrophils in the lung were not significantly different from the control group. Depletion of mouse neutrophils caused only a mild reduction in UVB-hPLTs accumulation in the lungs and a mild reduction in protein content in BALF. In comparison, depletion of mPLTs almost completely abolished hPLTs accumulation in the lung and significantly reduced protein content in BALF. UVB-treated hPLTs bound to host mPLTs, but did not bind to neutrophils in the lung. Aspirin treatment of hPLTs in vitro abolished hPLT accumulation in the lung and protected mice from lung injury. Our data indicate that host mPLTs accumulated in the lungs in response to an inflammatory challenge and subsequently mediated the attachment of transfused UVB-hPLTs. Neutrophils also recruited a small percentage of platelets to the lung. These findings may help develop therapeutic strategies for ALI which could potentially result from transfusion of UV illuminated platelets.

The next (re)generation of ovarian biology and fertility in women: is current science tomorrow's practice?

Stem cell-based strategies for ovarian regeneration and oocyte production have been proposed as future clinical therapies for treating infertility in women. However, utilization of embryonic stem cells or induced pluripotent stem cells to produce oocytes has had limited success in vitro. A recent report of the isolation and characterization of endogenous oocyte-producing or oogonial stem cells (OSCs) from ovaries of reproductive age women describes the first stable and pure human female germ cell culture model in which a subset of cells appear to initiate and complete meiosis. In addition, purified human OSCs introduced into adult human ovarian cortical tissue generate oocytes that arrest at the diplotene stage of meiosis and successfully recruit granulosa cells to form new primordial follicles. This overview examines the current landscape of in vitro and in vivo gametogenesis from stem cells, with emphasis on generation of human oocytes. Future research objectives for this area of work, as well as potential clinical applications involving the use of human OSCs, are discussed.

Recent advances in oocyte and ovarian tissue cryopreservation and transplantation

Options for preserving fertility in women include well-established methods such as fertility-sparing surgery, shielding to reduce radiation damage to reproductive organs, and emergency in-vitro fertilisation after controlled ovarian stimulation, with the aim of freezing embryos. The practice of transfering frozen or thawed embryos has been in place for over 25 years, and today is a routine clinical treatment in fertility clinics. Oocytes may also be frozen unfertilised for later thawing and fertilisation by intracytoplasmic sperm injection in vitro. In recent years, oocyte cryopreservation methods have further developed, reaching promising standards. More than 1000 children are born worldwide after fertilisation of frozen and thawed oocytes. Nevertheless, this technique is still considered experimental. In this chapter, we focus on options for fertility preservation still in development that can be offered to women. These include freezing of oocytes and ovarian cortex and the transplantation of ovarian tissue.

Comparison of in vitro- and chorioallantoic membrane (CAM)-culture systems for cryopreserved medulla-contained human ovarian tissue

At present, there are three ways to determine effectively the quality of the cryopreservation procedure using ovarian tissue before the re-implantation treatment: evaluation of follicles after post-thawing xenotransplantation to SCID mouse, in-vitro culture in a large volume of culture medium under constant agitation and culture on embryonic chorio-allantoic membrane within a hen's eggs. The aim of this study was to compare the two methods, culture in vitro and culture on embryonic chorioallantoic membrane (CAM) of cryopreserved human ovarian medulla-contained and medulla-free cortex. Ovarian fragments were divided into small pieces (1.5–2.0×1.0–1.2×0.8–1.5) of two types, cortex with medulla and medulla-free cortex, frozen, thawed and randomly divided into the following four groups. Group 1: medulla-free cortex cultured in vitro for 8 days in large volume of medium with mechanical agitation, Group 2: medulla-containing cortex cultured in vitro, Group 3: medulla-free cortex cultured in CAM-system for 5 days, Group 4: medulla-containing cortex cultured in CAM-system. The efficacy of the tissue culture was evaluated by the development of follicles and by intensiveness of angiogenesis in the tissue (von Willebrand factor and Desmin). For Group 1, 2, 3 and 4, respectively 85%, 85%, 87% and 84% of the follicles were morphologically normal (P>0.1). The immunohistochemical analysis showed that angiogenesis detected by von Willebrand factor was lower in groups 1 and 3 (medulla-free cortex). Neo-vascularisation (by Desmin) was observed only in ovarian tissue of Group 4 (medulla-contained cortex after CAM-culture). It appears that the presence of medulla in ovarian pieces is beneficial for post-thaw development of cryopreserved human ovarian tissue. For medical practice it is recommended for evaluation of post-warming ovarian tissue to use the CAM-system as a valuable alternative to xenotransplantation and for cryopreservation of these tissues to prepare ovarian medulla-contained strips.

Oocyte formation by mitotically active germ cells purified from ovaries of reproductive-age women

Germline stem cells that produce oocytes in vitro and fertilization-competent eggs in vivo have been identified in and isolated from adult mouse ovaries. Here we describe and validate a FACS-based protocol that can be used with adult mouse ovaries and human ovarian cortical tissue to purify rare mitotically-active cells that exhibit a gene expression profile consistent with primitive germ cells. Once established in vitro, these cells can be expanded for months and spontaneously generate 35–50 µm oocytes, as determined by morphology, gene expression and attainment of haploid (1n) status. Injection of the human germline cells, engineered to stably express GFP, into human ovarian cortical biopsies leads to formation of follicles containing GFP-positive oocytes 1–2 weeks after xenotransplantation into immunodeficient female mice. Thus, ovaries of reproductive-age women, like adult mice, possess rare mitotically-active germ cells that can be propagated in vitro as well as generate oocytes in vitro and in vivo.

Viability and function of the cryopreserved whole rat ovary: comparison between slow-freezing and vitrification

OBJECTIVE

To investigate four different protocols for cryopreservation of the whole rat ovary with intact vasculature to evaluate whether differences exist in post-thawing viability of the ovary after either vitrification or slow freezing.

DESIGN

Experimental study.

SETTING

Obstetrics and gynecology department.

ANIMAL(S)

Immature Sprague-Dawley female rats.

INTERVENTION(S)

Ovaries were isolated with the vascular tree intact up to the bifurcation of the abdominal aorta and were subsequently cannulated. The ovaries were flushed with increasing concentrations of the cryoprotectant dimethyl sulfoxide (DMSO) to either 1.5 or 7 M. The ovaries underwent cryopreservation by vitrification or passive slow freezing.

MAIN OUTCOME MEASURE(S)

After thawing, the ovaries were subjected to neutral red viability staining to assess the density of viable small follicles and for long-term (48 hours) incubation evaluation of steroid secretion, histology, and apoptosis assay.

RESULT(S)

The follicular viability was decreased in both vitrification groups and in the slow-freezing group with the high concentration of DMSO, as compared with fresh controls. Estradiol levels in the incubation medium followed the same pattern. Light microscopy revealed well-preserved morphology in all groups after 48 hours' incubation. Apoptosis was increased in both vitrified and cryopreserved ovaries.

CONCLUSION(S)

We have developed a new method that can be used in basic studies to improve cryopreservation protocols. Our initial findings suggest that a moderate concentration of the cryoprotectant DMSO is superior to a high DMSO concentration for both vitrification and slow freezing.

Safety of ovarian tissue autotransplantation for cancer patients

Cancer treatments can induce premature ovarian failure in almost half of young women suffering from invasive neoplasia. Cryopreservation of ovarian cortex and subsequent autotransplantation of frozen-thawed tissue have emerged as promising alternatives to conventional fertility preservation technologies. However, human ovarian tissue is generally harvested before the administration of gonadotoxic treatment and could be contaminated with malignant cells. The safety of autotransplantation of ovarian cortex remains a major concern for fertility preservation units worldwide. This paper discusses the main tools for detecting disseminated cancer cells currently available, their limitations, and clinical relevance.

Effect of graft site and gonadotrophin treatment on follicular development of canine ovarian grafts transplanted to NOD-SCID mice

PURPOSE

To investigate the effect of graft site and gonadotrophins administration on the number and survival rate of follicles of canine ovarian grafts transplanted to NOD-severe combined immune deficiency (SCID) mice.

METHODS

Fresh ovarian cortex slices obtained from immature bitches were grafted subcutaneously (SC), under kidney capsule (KC) or into ovarian bursa (OB) in NOD-SCID mice. Two months after surgery, the mice allocated into non-treated and treated gonadotrophins groups that injected with porcine follicle stimulating hormone during 7 days and human chorionic gonadotrophin 48 h later. Ovarian grafts were collected after 10 h of last injection and processed for histology.

RESULTS

The number of transitional and preantral follicles under KC and into OB was significantly higher in gonadotrophins-treated mice than those who received saline. Furthermore, the survival rates of primary, transitional and preantral follicles under KC and into OB grafts were significantly higher than those placed SC in the treated gonadotrophins group, and in the non-treated gonadotrophins group; the proportion of primary and preantral follicle survival was significantly higher under KC and into OB than SC grafts.

CONCLUSIONS

In canine ovarian xenografting, administration of gonadotrophin could be effective for improvement of survival of transplanted ovary. Furthermore, the grafting into OB appeared to be better than grafting under KC, which in turn is better than SC.

Assessment of canine ovaries autografted to various body sites

The influence of graft site on the survival of canine follicles and oocytes after autografting was investigated. Hemi-ovaries were autografted to three locations (quadriceps femoris muscle fascia, kidney capsule, and gastrosplenic ligament), and grafted ovaries were recovered (under anesthesia) 28 to 31 d after transplantation. The grafted hemi-ovaries were bisected: one-quarter ovary was used for histological assessment and another quarter for evaluation of oocyte viability. As controls, the remaining fresh hemi-ovaries were used to assess the viability of follicles and oocytes in non-transplanted ovaries. Most follicles in the histological sections of the grafts were classified as primordial or primary follicles. Antral follicles were not observed in the grafts, irrespective of the graft site. The percentages of viable follicles in the sections from control ovaries, and the ovaries grafted to the kidney capsule, the quadriceps femoris muscle fascia, and the gastrosplenic ligament were 17.4, 22.9, 18.3, and 32.4%, respectively. A total of 12 oocytes was recovered from the 15 hemi-ovaries grafted in five bitches, of which five (41.7%) oocytes from the ovaries grafted to the quadriceps femoris muscle fascia and the kidney capsule were cultured for assessment of meiotic competence. Three oocytes were viable but remained in the germinal vesicle stage after 72 h of maturation culture. The quadriceps femoris muscle fascia might be useful for grafting like the kidney capsule, but improvement of follicle survival and meiotic competence of oocytes in the grafts is necessary.

Xenografting of gonadal tissues into mice as a possible method for conservation and utilization of porcine genetic resources

In vitro production of embryos, including in vitro maturation, fertilization of oocytes and their subsequent culture to the embryo stage, has become the most popular method of studying gametogenesis and embryogenesis in pigs. As well as their utility for basic studies, these procedures now enable us to generate viable embryos and offspring as a means of conserving genetic resources and rare animal breeds. Recently, more advanced technologies such as xenografting of gonadal (testicular and ovarian) tissues into immunodeficient experimental animals have been developed. In combination with in vitro embryo production techniques, this approach may provide many benefits. We have been carrying out studies to acquire basic information about the application of this method to porcine species, and to improve the existing techniques. Recently, we obtained oocytes from ovarian tissue xenografted and grown in nude mice that had the capacity to be fertilized and the ability to develop into early-stage embryos. We also obtained spermatozoa from the xenografted testicular tissues and injected them intracytoplasmically into in vitro-matured oocytes to produce piglets. Here we discuss the further possibilities of conservation and utilization of porcine gonadal tissue by xenografting into immunodeficient mice.

Improving posttransplantation survival of human ovarian tissue by treating the host and graft

OBJECTIVE

To improve posttransplantation survival of frozen-thawed human ovarian tissue in immunodeficient mice.

DESIGN

Histologic study of transplanted human ovaries after treating the host and graft.

SETTING

Infertility unit, university-affiliated tertiary medical center.

PATIENT(S)

Ovarian tissue from six girls/women (aged 5-23 years) who had undergone ovarian laparoscopy for fertility preservation.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Thawed ovarian samples were transplanted into the back muscle of immunodeficient mice divided into four groups: A) no treatment; B) host treatment with vitamin E and gonadotropins before and after grafting; C) graft incubation with vascular endothelial growth factor A (VEGF-A) and vitamin E before transplantation; and D) host as in B, graft as in C. Ungrafted thawed samples served as control. Assessment of graft survival was conducted by follicle counts, apoptosis evaluation, immunohistochemical stainings for proliferating cell nuclear antigen (PCNA) and VEGF-A expression.

RESULT(S)

Only grafts incubated before transplantation (groups C and D) retained their original size. Follicle number was low in all grafts. PCNA expression was found in most grafts. Apoptosis was significantly lower in the untreated and treated grafts transplanted into treated hosts (groups B and D) than in ungrafted-thawed samples and group A grafts. All grafted groups had significantly higher expression of VEGF-A than ungrafted-thawed samples.

CONCLUSION(S)

Survival of transplanted human ovarian tissue may be improved by treatment of the host and graft. Further studies to evaluate treatments with a potential benefit in human ovarian autotransplantation are needed.

In vivo delivery of FTY720 prevents radiation-induced ovarian failure and infertility in adult female nonhuman primates

OBJECTIVE

To determine whether sphingosine-1-phosphate (S1P), or the S1P mimetic FTY720 shields ovaries of adult female rhesus monkeys from damage caused by 15 Gy of targeted radiotherapy, allowing for the retention of long-term fertility, and to evaluate whether S1P protects human ovarian tissue (xenografted into mice) from radiation-induced damage.

DESIGN

Research animal study.

SETTING

Research laboratory and teaching hospital.

PATIENT(S)

Adult female rhesus macaques (8-14 years of age; n = 21) and two women (24 and 27 years of age) undergoing gynecologic surgery for benign reasons, after informed consent and approval.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Ovarian histologic analysis, ovarian reserve measurements, and fertility in mating trials.

RESULT(S)

Rapid ovarian failure was induced in female macaques by ovarian application of 15 Gy of radiation. Females given S1P or FTY720 by direct intraovarian cannulation for 1 week before ovarian irradiation rapidly resumed menstrual cycles because of maintenance of follicles, with greater beneficial effects achieved using FTY720. Monkeys given the S1P mimetic before ovarian irradiation also became pregnant in mating trials. Offspring conceived and delivered by radioprotected females developed normally and showed no evidence of genomic instability, as measured by micronucleus frequency in reticulocytes. Adult human ovarian cortical tissue xenografted into mice also exhibited a reduction in radiation-induced primordial oocyte depletion when preexposed to S1P.

CONCLUSION(S)

S1P and its analogs hold clinical promise as therapeutic agents to preserve ovarian function and fertility in female cancer patients exposed to cytotoxic treatments.

Study on the vaginal smear of rats submitted to autologous ovarian transplant: impact of remote ischemic preconditioning

PURPOSE

To evaluate the remote ischemic preconditioning (R-IPC) impact on the quality of the ovarian graft by means of vaginal smear of transplanted rats.

METHODS

Sixty rats were used divided in six groups: Control; Fresh transplant (TxF); Cryopreserved transplant (TxC); R-IPC; R-IPC + fresh transplant (TxF+R-IPC); R-IPC + cryopreserved transplant (TxC+R-IPC). R-IPC was performed in the common iliac artery. Autologous ovarian tissue was implanted integrally in the retro peritoneum. On the first PO day, vaginal smear collection was daily initiated. After 30 days, the PO day when the estrous cycle was re-initiated was considered for analysis as well as the estrous days and the number of estrous cycles.

RESULTS

R-IPC showed a tendency to an early estrus re-initiation (p>0.05) as well as increase the number of cycles in the fresh transplanted group while in the cryopreserved transplant the number of cycles was similar, regardless of the stimulus R-IPC (p>0.05). The animals which had undergone fresh grafts had a longer estrous period than the ones which had undergone cryopreserved grafts, with or without R-IPC (p<0.05).

CONCLUSION

R-IPC promoted earlier re-initiation of ovarian activity in the PO and greater estrous frequency, with more consistent results in the fresh grafts than in the cryopreserved ones.

Testosterone induces activation of porcine primordial follicles in vitro

Purpose

The mechanism underlying primordial follicle activation is poorly understood. In this study, in-vitro culture and subsequent xenotransplantation were conducted to determine whether testosterone promotes the activation of porcine primordial follicles.

Methods

Prepubertal porcine ovarian cortical strips containing primordial follicles were cultured in the presence of testosterone for 7 days, and subsequently transplanted to immunodeficient mice for 2 months. After culture and transplantation, development of follicles was examined histologically. The presence of androgen receptors in oocytes was assessed by use of western blot and immunohistochemical analyses.

Results

Testosterone at 10^-6 m induced the primordial follicle transition to the intermediate (19 ± 4%) and primary (3 ± 1%) stages after 7-day culture, while 56 ± 5% of primordial follicles remained in the initial pool. Higher concentrations, above 10^-5 m, or lower concentrations, below 10^-6 m, did not induce follicle transition to the primary stage. After 7-day culture with 10^-6 m testosterone, ovarian cortical strips were transplanted to immunodeficient mice. Some of the follicles developed to the secondary (15 ± 3%) and antral (10 ± 3%) stages, whereas 44 ± 7% of primordial follicles remained in the initial pool. In the culture experiment, estradiol-17β (10^-7-10^-5 m) had no significant effect on follicle activation. The androgen receptor antagonist, cyproterone acetate, inhibited the stimulatory effect of testosterone on primordial follicle activation, suggesting an androgen receptor-mediated action of testosterone. Western blot and immunohistochemical analyses revealed that androgen receptors were present in the oocytes of primordial follicles.

Conclusions

These results suggest that testosterone at 10^-6 m promotes the activation of porcine primordial follicles in vitro through the androgen receptors in the oocytes.