Ovarian tissue cryopreservation and transplantation: a review

Fertility preservation in cancer patients using stored ovarian tissue: clinical aspects

PURPOSE OF REVIEW

This review covers the medical approach and laboratory guidelines needed for fertility preservation using stored ovarian tissue in cancer patients. Indications, careful patient selection and timing are essential. Techniques for tissue harvesting and storage are evaluated. Up-to-date information on publications reporting on transplantation, recovery of endocrine function, pregnancy and delivery of healthy babies is reviewed as well as relevant data on safety measures to detect cancer cells in stored ovarian tissue.

RECENT FINDINGS

Recent literature review indicates 12 pregnancies, five deliveries of healthy babies and two ongoing pregnancies after transplantation of ovarian tissue using different methods. To increase the safety of ovarian tissue cryopreservation-reimplantation procedures, algorithm and methods to identify tumor involvement in the ovaries and detection of small numbers of cancer cells in ovarian tissue were recently reported.

SUMMARY

Cryopreservation of ovarian tissue has been practiced for over a decade in an attempt to preserve fertility before the commencement of potentially sterilizing chemotherapy. With more than a few recent reports on pregnancies and deliveries after transplantation of ovarian tissue, there will be more patients requesting the storage of ovarian tissue in order to preserve fertility prior to cancer treatments.

Beneficial effect of desialylated erythropoietin administration on the frozen-thawed canine ovarian xenotransplantation

PURPOSE

The main drawback of ovarian cryopreservation followed by transplantation is that a large proportion of follicles are lost after transplantation. Thus, effects of erythropoietin (EPO) and desialylated EPO administration on the frozen-thawed canine ovarian xenotransplantation were examined.

METHODS

The protective and survival-promoting effects of EPO and desialylated EPO on the follicles of frozen-thawed canine ovaries after transplantation were examined using NOD-SCID mice. Frozen-thawed dog ovarian tissue with 400 U/kg of EPO or asialo EPO was placed into the ovarian bursa.

RESULTS

At 4 weeks after the transplantation, the ovaries were removed and subjected to histological examination. The survival rate of early primary follicles was 15.2% in the EPO group and 157.6% in the asialo EPO group, in contrast to 10.1% in the untreated group.

CONCLUSIONS

These results demonstrate that administration of asialo EPO could be effectively used to enhance the survival of the follicles of transplanted cryopreserved ovaries.

Cryopreservation/transplantation of ovarian tissue and in vitro maturation of follicles and oocytes: challenges for fertility preservation

Cryopreservation of ovarian tissue and in vitro follicle maturation are two emerging techniques for fertility preservation, especially in cancer patients. These treatment regimes are opening up more options and allow for more suitable choices to preserve fertility according to the patient's specific circumstances. If these technologies are to become widely accepted, they need to be safe, easy to perform and must obtain favorable results. The generation of healthy eggs with the normal genetic complement and the ability to develop into viable and healthy embryos requires tight regulation of oocyte development and maturation. Novel freezing techniques such as vitrification, along with whole ovary cryopreservation and three-dimensional follicle cultures, have shown favorable outcomes. The scope of this article is to take a comprehensively look at the challenges still faced in order for these novel technologies to be routinely employed with the aim of successful fertility preservation.

Orthotopic transplantation of neonatal GFP rat ovary as experimental model to study ovarian development and toxicology

The rat is one of the most commonly used experimental animal species in biomedical research. The availability of new research tools in rats could therefore provide considerable advances in the areas where this mammal is extensively used. We report the development of a new green fluorescent protein (GFP) rat strain suitable for organ transplantation and the birth of GFP rats following orthotopic transplantation of neonatal ovaries from this newly developed GFP rat strain to a wild-type Fischer 344 (F344) strain. A new GFP rat strain was developed by backcrossing eGFP Sprague-Dawley (SD-Tg(CAG-EGFP)Cz-004Osb) to wild-type F344 for eight generations. Whole ovaries from postnatal day (PND) 8 or PND 21 GFP rats were transplanted orthotopically to bilaterally ovariectomized wild-type adult females (n=6). All recipients were mated, and three of the five resulting litters contained GFP pups. In the PND 8 group, all recipients cycled regularly and the ovarian morphology appeared normal when collected at 9 months post-transplantation. In the PND 21 group, 60% of the recipients displayed regular estrous cycles at 9 months post-transplantation, but showed reduced ovarian size. This new strain and neonatal orthotopic transplantation could be useful for many biomedical fields including transplantation, development, and reproductive toxicology.

Abnormally low expression of connexin 37 and connexin 43 in subcutaneously transplanted cryopreserved mouse ovarian tissue

PURPOSE

To analyze the gap junction proteins connexin 37 (Cx37) and connexin 43 (Cx43) after subcutaneous transplantation of cryopreserved mouse ovarian tissue.

METHODS

Expression of gap junction genes was assessed by immunohistochemistry and real-time polymerase chain reaction (PCR) in transplanted cryopreserved ovarian tissue compared with that of normal ovarian tissue. Apoptosis of ovarian cells was evaluated by using the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphates nick end-labeling method.

RESULTS

After subcutaneous transplantation, Cx37 and Cx43 mRNA and protein expression were significantly lower in cryopreserved than in normal ovarian tissue. Apoptosis was increased in granulosa cells from antral follicles of the cryopreserved tissue.

CONCLUSION

After cryopreservation and subcutaneous transplantation of ovarian tissue, proteins forming gap junctions between oocytes and granulosa cells are under-expressed compared with normal controls.

Preservation of fertility in young cancer patients: contribution of transmission electron microscopy

During the last decade, new technologies in reproductive medicine have emerged to preserve the fertility of women whose gonadal function is threatened by premature menopause or gonadotoxic treatments. To offer an individualized approach to these patients, different experimental procedures are under investigation, including oocyte cryopreservation and cryopreservation and transplantation of ovarian tissue in the form of cortical fragments, whole ovary or isolated follicles. This review shows that transmission electron microscopy (TEM), combined with other in-vivo and in-vitro analysis techniques, is a valuable tool in the establishment of new experimental protocols to preserve female fertility. Ultrastructural studies allow in-depth evaluation of the oocyte's unique morpho-functional characteristics, which explain its low cryotolerance, and provide essential information on follicular, stromal and endothelial cell integrity, as well as cellular interactions crucial for normal folliculogenesis. In order to be able to offer appropriate and efficient options in every clinical situation, oocyte in-vitro maturation and ovarian tissue transplantation need to be optimized. Further development of new approaches, such as follicular isolation and whole ovary transplantation, should be encouraged. Fine ultrastructural details highlighted by TEM studies will be useful for the further optimization of these emerging technologies.

Electron paramagnetic resonance as a tool to evaluate human ovarian tissue reoxygenation after xenografting

OBJECTIVE

To develop electron paramagnetic resonance (EPR) oximetry as a tool to characterize the oxygen environment in human ovarian xenografts in the early postgrafting period.

DESIGN

Prospective experimental study.

SETTING

Gynecology research unit in a university hospital.

PATIENT(S)

Biopsies were obtained from 6 women aged 22-35 years.

INTERVENTION(S)

Frozen-thawed human ovarian tissue fragments were grafted to an intraperitoneal site in nude mice. Before grafting, lithium phthalocyanine, an oxygen reporter, was implanted inside the fragments.

MAIN OUTCOME MEASURE(S)

To monitor partial pressure of oxygen (pO(2)) by EPR on postgrafting days 3, 5, 7, 10, 14, 17, and 21 and validate the technique by histologic assessment.

RESULT(S)

A period of hypoxia was identified before day 5, followed by gradual but significant oxygenation over the next 5 days, suggesting an active process of graft revascularization. Reoxygenation kinetics in human ovarian xenotransplants were quantified.

CONCLUSION(S)

Our data validated the EPR oximetry technique as a tool to monitor pO(2) in ovarian grafting. The critical early period of hypoxia was identified, and the first steps of reoxygenation were characterized. In the future, our model may be used to evaluate new freezing and grafting protocols with the aim of reducing potential cryoinjury and initial ischemia-reperfusion damage.

Ovarian cryopreservation for fertility preservation: indications and outcomes

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

Fertility and impact of pregnancies on the mother and child in classic galactosemia

Despite the high prevalence of premature ovarian failure (POF) and subsequent infertility in galactosemic women, spontaneous pregnancies occur and may not be as rare as is generally assumed. This is important for counseling these women on fertility. The purpose of this review is to assess the occurrence and predicting factors of pregnancy, and to evaluate the impact of pregnancy on the mother's and child's health. The female Dutch galactosemia population (age > 18 years) was studied, and a literature search on articles reporting pregnancy in galactosemic women, published between January 1971 and December 2007, was performed. Twenty-two galactosemic women were studied. Nine women have tried to conceive, of which 4 were successful. Three mothers were diagnosed with POF before the first pregnancy and/or in between pregnancies. In literature, 50 pregnancy reports were found. In 10 pregnancy reports from the literature, the mother's genotype is known. Four women were homozygous for the Q188R mutation, which equals the incidence of 40-45% of classic galactosemia caused by this mutation. This study challenges the current opinion that the chance of becoming pregnant is small in classic galactosemia. Despite POF in most galactosemic women, pregnancies do occur. The genotype and GALT-activity do not seem to predict the chance of becoming pregnant, whereas the occurrence of spontaneous menarche might. No evidence for the need of additional check-ups during the pregnancy and puerperium was found. Elevations in galactose-metabolites do occur, but without evidence of clinical impact for the mother or the child, although possible long-term effects have not been thoroughly investigated.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to summarize the purported causes and sequelae of galactosemia, explain the possible sequelae of galactosemia, distinguish alterations of the ovary and the hypothalamic-pituitary axis, identify the frequency of pregnancy and the possible outcome of the offspring, and outline dietary management of patients with galactosemia.

Indirect evaluation of estrogenic activity post heterotopic ovarian autograft in rats

PURPOSE

To morphologically evaluate the estrogenic effect on the uterus and vagina of rats submitted to ovarian autografts.

METHODS

Twenty Wistar EPM-1 adult rats were bilaterally ovariectomized, followed by ovarian transplants in retroperitoneal regions. The animals were divided in four groups of five animals, according to the day of euthanasia: G4, G7, G14 and G21, corresponding to the 4th, 7th, 14th and 21st day after surgery, respectively. Vaginal smears were collected from the first day of surgery until euthanasia day. After that, the vagina and uterus were removed, fixed in 10% formaldehyde and submitted to histological analysis and stained with hematoxiline and eosine.

RESULTS

All animals showed estrous cycle changes during the experiment. In 4th day, the uterus showed low action of estrogen with small number of mitosis and eosinophils as well as poor development. On the 7th day, the endometrium was atrophic without mitotic signals and presented a small number of eosinophils. On the 14th and 21th days the histological findings were similar, with the presence of mitosis in the endometrial glands and intense leucocyte infiltration with a large number of eosinophils. Morphometric results showed that the endometrial and myometrial thickness as well as the number of eosinophils presented the highest values during the 14th and 21th days of the evaluation. The 7th day group also presented the lowest eosinophil numbers. Vaginal epithelium features were: 4th and 7th day groups presented non-keratinized stratified epithelium with 5 and 2 cell layers, respectively. The 14th and 21st day groups presented non-keratinized stratified epithelium with 14 and 15 cell layers.

CONCLUSION

Experimental ovarian autografts in the evaluated organs presented maximum estrogen activity after the 21st day of surgery, according to morphological and morphometric data.

Cryopreservation and xenotransplantation of human ovarian tissue: an ultrastructural study

OBJECTIVE

To analyze the ultrastructure of human ovarian follicles after cryopreservation and short-term xenografting.

DESIGN

Prospective experimental study.

SETTING

Academic gynecology and anatomy research units.

PATIENT(S)

Ovarian cortical biopsy specimens were obtained from 13 patients.

INTERVENTION(S)

Each ovarian biopsy specimen was dissected into pieces of 1 mm(3) and divided into three groups: [1] fresh tissue, [2] frozen-thawed tissue, and [3] frozen-thawed tissue xenografted onto the peritoneum of nude mice for 3 weeks.

MAIN OUTCOME MEASURE(S)

Follicular ultrastructure was assessed by light and transmission electron microscopy in [1] fresh, [2] frozen, and [3] frozen-grafted tissue.

RESULT(S)

Thirty-five ovarian follicles were analyzed by light and transmission electron microscopy. Twenty-five primordial and primary ovarian follicles were found. Most of them exhibited ultrastructurally well preserved features (fresh [N = 8/10], frozen [N = 7/10], and frozen-grafted [N = 4/5] tissue). Ten secondary follicles were present in xenografts. By transmission electron microscopy, all the healthy-looking secondary follicles (70%) were shown to contain intact oocytes, with features typical of earlier developmental stages, surrounded by several layers of follicular cells.

CONCLUSION(S)

The present study demonstrates, for the first time, that cryopreservation and xenotransplantation do not appear to greatly affect human primordial/primary follicle ultrastructure. Interestingly, in frozen-thawed xenografts, secondary human ovarian follicles presented a well preserved ultrastructure, but asynchrony between oocyte and granulosa cell development was detected. The possible causes for this asynchrony are discussed.

Difficulties improving ovarian functional recovery by microvascular transplantation and whole ovary vitrification

OBJECTIVE

To evaluate recovery of endocrine function and fertility after transplantation and vitrification of whole ovaries.

DESIGN

Animal study.

SETTING

Lyon Veterinary School, France.

ANIMAL(S)

Ewes.

INTERVENTION(S)

In group 1 (n = 5), the left ovary was removed with its vascular pedicle and was transplanted onto the contralateral pedicle. In group 2 (n = 5), the left ovary with its pedicle was cryopreserved after a vitrification procedure. After thawing, transplantation was performed by microvascular anastomosis to the contralateral ovarian pedicle.

MAIN OUTCOME MEASURE(S)

Median ischemia time, progesterone levels, histologic examination.

RESULT(S)

Successful microsurgical transplantation was performed in both groups. The median ischemia time was statistically significantly longer in group 2 (287 minutes, range: 226 to 349] versus 129 minutes [range: 125 to 130]) in group 1. In group 1, four sheep recovered spontaneous ovarian endocrine function about 2.5 (range: 2.00 to 3.75) months after transplantation. Two ewes gave healthy live births at 12 and 25 months, respectively, after transplantation. In group 2, one ewe recovered ovarian endocrine function 6 months after transplantation. However, histologic evaluation showed a follicular survival rate of 6% in group 1, and total follicle loss in group 2.

CONCLUSION(S)

Autograft of whole sheep ovaries with microvascular anastomosis seems technically feasible but resulted in a very poor follicle survival rate (6%), in spite of endocrine function recovery and birth of two lambs. Attempts at cryopreservation with vitrification resulted in no follicle survival at all.

Morphology and function of cryopreserved whole ovine ovaries after heterotopic autotransplantation

BACKGROUND

The objective of this study was to perform complex characterization of cryopreserved and then autotransplanted ovaries including determination of the ability to respond to in vivo follicle stimulating hormone (FSH)-treatment, fertilizability of retrieved oocytes, and morphology, vascularization, cellular proliferation and apoptosis in sheep.

METHODS

Mature crossbred ewes were divided into two groups; an intact (control) group (n = 4), and autotransplanted group (n = 4) in which oophorectomy was performed laparoscopically and ovaries with intact vascular pedicles frozen, thawed and transplanted back into the same animal at a different site. Approximately five months after autotransplantation, estrus was synchronized, ewes were treated with FSH, and ovaries were collected. For all ovaries, number of visible follicles was determined, and collected cumulus oocyte complexes (COC) were matured and fertilized in vitro. Remaining ovarian tissues were fixed for evaluation of morphology, expression of factor VIII (marker of endothelial cells), vascular endothelial growth factor (VEGF; expressed by pericytes and smooth muscle cells), and smooth muscle cell actin (SMCA; marker of pericytes and smooth muscle cells), and cellular proliferation and apoptosis. Two fully functional ovaries were collected from each control ewe (total 8 ovaries).

RESULTS

Out of eight autotransplanted ovaries, a total of two ovaries with developing follicles were found. Control ewes had 10.6 +/- 2.7 follicles/ovary, oocytes were in vitro fertilized and developed to the blastocyst stage. One autotransplanted ewe had 4 visible follicles from which 3 COC were collected, but none of them was fertilized. The morphology of autotransplanted and control ovaries was similar. In control and autotransplanted ovaries, primordial, primary, secondary, antral and preovulatory follicles were found along with fully functional vascularization which was manifested by expression of factor VIII, VEGF and SMCA. Proliferating cells were detected in follicles, and the rate of apoptosis was minimal in ovaries of control and autotransplanted ovaries.

CONCLUSION

These data demonstrate successful autotransplantation of a portion of frozen/thawed ovaries manifested by restoration of selected ovarian function including in vitro maturation of collected oocytes, presence of follicles from several stages of folliculogenesis and blood vessels expressing specific markers of vascularization, and proliferation and apoptosis of ovarian cells. Thus, heterotopic autotransplantation of a whole frozen/thawed ovary allows for development of preovulatory follicles, oocyte growth, and for restoration of vascularization and cellular function. However, additional improvements are required to enhance the efficiency of autotransplantation of frozen/thawed ovaries to produce more oocytes.

First retransplantation of cryopreserved ovarian tissue following cancer therapy in Germany

INTRODUCTION

New anticancer treatments have increased survival rates for cancer patients but often at the cost of sterility. One way of preserving fertility in these patients is the use of cryopreservation of ovarian tissue with subsequent retransplantation following a period of recurrence-free survival. We report the follow-up of the first case of retransplantation of ovarian tissue in Germany.

METHODS

Immediately following the diagnosis of anal cancer, ovarian tissue was removed laparoscopically, and cryopreserved. The patient was then treated with combined radiochemotherapy, which resulted in iatrogenic premature ovarian failure, and was associated with inhibin B serum levels lower than 10 ng/L. After the 2.5 year period of cancer remission, the cryopreserved ovarian tissue was retransplanted orthotopically.

RESULTS

Five months later estradiol serum levels had risen from lower than 20 pg/mL to 436 pg/mL. Three ovarian follicles were detected ultrasonographically in the pelvic side wall. Finally the patient reported her first menstruation after the intervention. The endocrine activity of the transplanted cryopreserved tissue has demonstrated viability, and the ability to develop.

DISCUSSION

Cycle monitoring and timed intercourse should now help to achieve conception. These first results from Germany for retransplantation of cryopreserved ovarian tissue clearly show its potential for preserving fertility.

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

OBJECTIVE

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

DESIGN

Retrospective analysis of case series.

SETTING

University teaching hospital.

PATIENT(S)

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

INTERVENTION(S)

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

MAIN OUTCOME MEASURE(S)

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

RESULT(S)

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

CONCLUSION(S)

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

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

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

Preservation of female fertility during cancer treatment

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

Ovarian and oocyte cryopreservation

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Fertility issues in survivors from adolescent cancers

Infertility is a common and distressing late-effect of cancer treatment. Whist sperm banking for post-pubertal males and embryo freezing for women (who are in a stable relationship at the time of treatment) are highly successful fertility preservation strategies, for females without a partner (including young and pre-pubescent girls) and pre-pubescent boys (or azoospermic men), there remain no effective approaches. Whilst the biological effects of cancer treatments on the reproductive system are well described, there are few data on the relative incidence of infertility (failure to conceive after one year of trying) in cancer survivors. This makes it difficult to advise survivors about their future fertility prospects. Whilst some will undoubtedly conceive naturally with their partner, others will require assisted conception treatment of which in vitro fertilisation (IVF) and intra-cytoplasmic sperm injection (ICSI) are the most common. Pregnancy outcomes of cancer survivors are generally good, although there is increased risk of pre-term birth and low birth-weight in the offspring of women who have received pelvic irradiation. There is no increased incidence of genetic disease or cancer incidence in the offspring of cancer survivors. Current research directions are focussing on alternative fertility preservation strategies including in vitro maturation techniques, xenotransplantation and the development of technology to create artificial gametes in the laboratory. Finally, although the reproductive techniques discussed are highly effective, country specific differences in the legal framework means that cancer survivors may be denied access to certain treatments (e.g. embryo cryopreservation) because they are forbidden by specific national legislation.

La cryopréservation de tissus composites: principe, revue de la littérature et expérience de l'équipe bordelaise

The cryopreservation of cells and human tissues has generated a great interest from the scientific community since 1949 when the cryoprotective activity of glycerol was discovered. For a homogeneous cellular group or a one-layer cellular tissue it is easy to define the optimal technique conditions of its cryopreservation (cryoprotective agents, speed and steps of freezing, speed of warming). It is considered successful when a high recovery of the cellular structures and tissue components after warming is achieved. The cryopreservation of a whole composite tissue is less easy to obtain. Each tissue presents its own parameters and its own reactivity during the cryopreservation process. The challenge consists in, on the one hand, the selection of the ideal cryoprotective agents'combination which can fit the needs of the different tissues and on the other hand, the definition of adequate technical parameters. The aim of this work is to demonstrate the feasability to cryopreserve a composite tissue in order to carry out surgical reconstructive procedures of particular anatomical and functionnal units (metacarpo-phalangeal and proximal interphalangeal joints, flexor system apparatus, extensor system, median nerve, etc.) with complete revitalization of the allograft using vascular microsurgical procedures. To do so, our present work is divided into three different parts. The first chapter deals with the fundamental principles of the cryobiology of biological structures with special interest in the liquid transfer process between the extracellular and intracellular compartments and ice initiation and agregation during the freezing process. The different physical and chemical reactions and their consequences on the biological tissues are described according to the different cryoprotective agents used, should they belong to the extracellular or intracellular cryoprotective groups. The second chapter makes a review of the litterature concerning the results of all experiments made on the cryopreservation of the different tissue structures as skin, vessels, bones, cartilage, periosteum, nerves, cornea, on the one hand, and the different organs as kidneys, liver, heart, trachea, lung, parathyroid glands and ovaries, on the other hand. We are reporting the results of these experiments focusing on the immunomodulation effect of cryopreservation on the antigenic response of biological structures. These experiments were made either on organs or on the cells involved in the immunogenic process. In the third chapter, we are reporting the results of our experiments carried out in the Aquitaine Hand Institute in the field of the cryopreservation of the xenografts of digital segments on the rabbit. These digital segments were cryopreserved, then warmed and revitalized through vascular microsurgical techniques. The preliminary results are very encouraging and pave the way to the allotransplantation of cryopreserved composite organs in our common surgical activity.

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

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

Pregnancy in women who had cancer in childhood

The majority of female cancer survivors will have normal reproductive function and would be expected to have a successful pregnancy. For the minority of young women who have received significant cytotoxic insult to the reproductive organs and yet still manage to conceive, pregnancy must be considered a high risk condition and these patients should be managed by a multidisciplinary specialist team. Female survivors of childhood cancer who are able to become pregnant carry an excess risk of preterm delivery and low birth weight baby. This restricted foetal growth and inability of the uterus to carry the foetus to term is associated with radiation-induced damage to the uterus. Chemotherapy does not appear to be associated with adverse pregnancy outcomes. However, prospective follow-up of cohorts of patients treated with contemporary therapies, frequently involving more intensive therapies are required to determine the risk. A number of large multi-centre studies, are underway and will provide new insights into pregnancy outcomes in survivors of childhood cancer.

Short-term transplantation of isolated human ovarian follicles and cortical tissue into nude mice

This study was designed to evaluate follicular survival and growth after short-term transplantation of fresh isolated human follicles and ovarian cortical tissue to nude mice. Ovarian biopsies were obtained from nine women undergoing laparoscopy. Twelve nude mice were xenografted with an ovarian cortical fragment in the right ovarian bursa, and a clot containing isolated follicles in the left, for a period of 7 days. One ungrafted fragment was used as a control. Histological sections were analyzed to determine follicle number and stage. The proliferative status of follicular cells was assessed by Ki-67 immunostaining. A total of 659 follicles was analyzed by histology and 545 follicles by immunohistochemistry. The percentage of primordial follicles was found to be markedly reduced 1 week post-grafting when compared with ungrafted tissue, while the percentage of primary follicles had significantly increased. Only 8% of follicles showed Ki-67-positive granulosa cells before grafting, whereas 1 week after grafting, 71% of follicles in fragments and 67% of isolated follicles were Ki-67-positive (P<0.001). Moreover, the histological aspect of isolated follicle grafts was similar to that of grafted fragments: follicles were surrounded by vimentin-positive stroma-like tissue of human origin, as confirmed by fluorescent in situ hybridization with human-specific probes. Our results demonstrate, for the first time, that isolated human follicles are able to survive and grow after xenografting. This study also shows massive in vivo follicular activation after transplantation of grafted fragments and isolated follicles. One week after grafting, well-structured stroma-like tissue of human origin was observed around the isolated follicles. The potential origin of this stroma is discussed.

Engineering the follicle microenvironment

In vitro ovarian follicle culture provides a tool to investigate folliculogenesis, and may one day provide women with fertility-preservation options. The application of tissue engineering principles to ovarian follicle maturation may enable the creation of controllable microenvironments that will coordinate the growth of the multiple cellular compartments within the follicle. Three-dimensional culture systems can preserve follicle architecture, thereby maintaining critical cell-cell and cell-matrix signaling lost in traditional two-dimensional attached follicle culture systems. Maintaining the follicular structure while manipulating the biochemical and mechanical environment will enable the development of controllable systems to investigate the fundamental biological principles underlying follicle maturation. This review describes recent advances in ovarian follicle culture, and highlights the tissue engineering principles that may be applied to follicle culture, with the ultimate objective of germline preservation for females facing premature infertility.

[What are at present the real hopes of pregnancy after ovarian cryopreservation?]

Survival rates for cancers that occur in childhood and adolescence have improved over the last decades, and preservation of future fertility in these patients has become a relevant issue. Premature ovarian failure is a consequence of exposing women to chemotherapeutic drugs and ionizing radiation. Ovarian cryopreservation is an alternative to cryopreservation of embryos or oocytes for theses patients. Ovarian cryopreservation aims to reimplant ovarian tissue after complete remission into the pelvic cavity (orthotopique site) or a heterotopic site like the abdominal wall or the forearm. In vitro folliculogenesis, that aims at the maturation of ovarian cortex primordial follicles cryopreserved for a FIV, is still in an experimental research stage. In this review, the objective was to evaluate the real hopes of pregnancy after ovarian cryopreservation. Indeed, many teams offer ovarian cryopreservation at present time, although only two pregnancies have been achieved to date. In both cases, it can be discussed whether the fertilized oocyte originated from the transplant or from the native ovary. Furthermore, the potential for reintroduction of cancerous cells may limit this technique in cancers that are known to have a risk of ovarian dissemination. The hopes engendered by ovarian cryopreservation, but also its limits, must be explained to the patients before an ovarian surgery for cryopreservation.

Laparoscopic ovariectomy for whole human ovary cryopreservation: technical aspects

OBJECTIVE

To describe the technique of laparoscopic ovariectomy with a view to cryopreservation of a whole ovary with its vascular pedicle.

DESIGN

Descriptive study.

SETTING

Gynecology research unit in a department of gynecology in a university hospital.

PATIENT(S)

Women with indications for chemotherapy or radiotherapy who are at high risk of premature ovarian failure.

INTERVENTION(S)

Laparoscopic ovariectomy for whole ovary cryopreservation in nine patients.

MAIN OUTCOME MEASURE(S)

Feasibility of laparoscopic ovariectomy for whole ovary cryopreservation and later autotransplantation without delaying chemotherapy.

RESULT(S)

The whole ovary was successfully removed by laparoscopy and cryopreserved by arterial catheterization in all nine patients.

CONCLUSION(S)

Ovariectomy with a view to whole ovary cryopreservation for future transplantation may be performed by laparoscopy. Great care must be taken to remove the ovary, together with a large part (> or =5 cm) of the infundibulopelvic ligament, allowing dissection of the ovarian vessels, perfusion with a cryoprotective medium, and cryopreservation for subsequent autografting of the whole ovary. The period of ischemia between ligation of the ovarian pedicle and ovarian cryopreservation must be as short as possible.

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

Fertility preservation in childhood cancer has become an important area of investigation due to increasing survival rates after cancer therapy. For these patients with an increased risk of infertility and premature ovarian failure, cryopreservation of ovarian tissue is a promising tool to preserve at least part of the reproductive potential. In recent years significant improvements have been achieved in this area, and 2 live births after autografting of frozen-thawed ovarian tissue have been reported. However, further research is needed to assess the clinical effectiveness of ovarian cryopreservation, to optimize the technique, and to limit the risk of reintroducing cancer cells in the patient with the graft.

Production of the first offspring from oocytes derived from fresh and cryopreserved pre-antral follicles of adult mice

Although mammalian ovaries contain hundreds of thousands of pre-antral follicles, fewer than 1% of these reach maturity and ovulation. Obtaining immature eggs from the pre-antral follicles of ovarian tissue could increase the possibility of preserving fertility in women undergoing anti-cancer treatment, and in women who wish to delay pregnancy and child raising until they are older. This study reports the birth of 10 healthy mouse pups derived from oocytes obtained from pre-antral follicles after adult ovary tissue cryopreservation and allotransplantation. High in-vitro maturation (55.1%), fertilization (76.3%) and cleavage (98.3%) rates were achieved using these oocytes, and there was no significant difference between the vitrified and control samples except in maturation rate (55.1 versus 72.8%, P < 0.05). After an ultra-rapid vitrification procedure, the warmed tissue fragments were transplanted beneath the kidney capsule of severe combined immunodeficient mice for onward in-vivo culture. Within 10 days of culture, 138 full size oocytes developed from the 456 transplanted pre-antral follicles. In-vivo growth of follicles was followed by in-vitro oocyte maturation, in-vitro fertilization and subsequent embryo transfer, leading to the birth of 10 healthy pups. These results may lead to increasing the possibility of preserving fertility by cryopreservation of ovarian tissue.