The role of cryopreservation for women prior to treatment of malignancy

Adipose-derived stem cell-secreted factors promote early stage follicle development in a biomimetic matrix

Development of primary follicles in vitro benefits from a three-dimensional matrix that is enriched with paracrine factors secreted from feeder cells and mimics the in vivo environment. In this study, we investigated the role of paracrine signaling from adipose-derived stem cells (ADSCs) in supporting primary follicle development in a biomimetic poly(ethylene glycol) (PEG)-based matrix. Follicles co-cultured with ADSCs and follicles cultured in conditioned medium from ADSCs encapsulated in gels (3D CM) exhibited significantly (p < 0.01 and p = 0.09, respectively) improved survival compared to follicles cultured in conditioned medium collected from ADSCs cultured in flasks (2D CM) and follicles cultured without paracrine support. The gene expression of ADSCs suggested that the stem cells maintained their multipotency in the 3D PEG environment over the culture period, regardless of the presence of the follicles, while under 2D conditions the multipotency markers were downregulated. The differences in cytokine signatures of follicles exposed to 3D and 2D ADSC paracrine factors suggest that early cytokine interactions are key for follicle survival. Taken together, the biomimetic PEG scaffold provides a three-dimensional, in vivo-like environment to induce ADSCs to secrete factors which promote early stage ovarian follicle development and survival.

Update on fertility preservation from the Barcelona International Society for Fertility Preservation-ESHRE-ASRM 2015 expert meeting: indications, results and future perspectives

STUDY QUESTION

What progress has been made in fertility preservation (FP) over the last decade?

SUMMARY ANSWER

FP techniques have been widely adopted over the last decade and therefore the establishment of international registries on their short- and long-term outcomes is strongly recommended.

WHAT IS KNOWN ALREADY

FP is a fundamental issue for both males and females whose future fertility may be compromised. Reproductive capacity may be seriously affected by age, different medical conditions and also by treatments, especially those with gonadal toxicity. There is general consensus on the need to provide counselling about currently available FP options to all individuals wishing to preserve their fertility.

STUDY DESIGN, SIZE, DURATION

An international meeting with representatives from expert scientific societies involved in FP was held in Barcelona, Spain, in June 2015.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Twenty international FP experts belonging to the American Society of Reproductive Medicine, ESHRE and the International Society of Fertility Preservation reviewed the literature up to June 2015 to be discussed at the meeting, and approved the final manuscript. At the time this manuscript was being written, new evidence considered relevant for the debated topics was published, and was consequently included.

MAIN RESULTS AND THE ROLE OF CHANCE

Several oncological and non-oncological diseases may affect current or future fertility, either caused by the disease itself or the gonadotoxic treatment, and need an adequate FP approach. Women wishing to postpone maternity and transgender individuals before starting hormone therapy or undergoing surgery to remove/alter their reproductive organs should also be counselled accordingly. Embryo and oocyte cryopreservation are first-line FP methods in post-pubertal women. Metaphase II oocyte cryopreservation (vitrification) is the preferred option. Cumulative evidence of restoration of ovarian function and spontaneous pregnancies after ART following orthotopic transplantation of cryopreserved ovarian tissue supports its future consideration as an open clinical application. Semen cryopreservation is the only established method for FP in men. Testicular tissue cryopreservation should be recommended in pre-pubertal boys even though fertility restoration strategies by autotransplantation of cryopreserved testicular tissue have not yet been tested for safe clinical use in humans. The establishment of international registries on the short- and long-term outcomes of FP techniques is strongly recommended.

LIMITATIONS, REASONS FOR CAUTION

Given the lack of studies in large cohorts or with a randomized design, the level of evidence for most of the evidence reviewed was three or below.

WIDER IMPLICATIONS OF THE FINDINGS

Further high quality studies are needed to study the long-term outcomes of FP techniques.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

N/A.

Update on fertility preservation from the Barcelona International Society for Fertility Preservation-ESHRE-ASRM 2015 expert meeting: indications, results and future perspectives

STUDY QUESTION

What progress has been made in fertility preservation (FP) over the last decade?

SUMMARY ANSWER

FP techniques have been widely adopted over the last decade and therefore the establishment of international registries on their short- and long-term outcomes is strongly recommended.

WHAT IS KNOWN ALREADY

FP is a fundamental issue for both males and females whose future fertility may be compromised. Reproductive capacity may be seriously affected by age, different medical conditions and also by treatments, especially those with gonadal toxicity. There is general consensus on the need to provide counselling about currently available FP options to all individuals wishing to preserve their fertility.

STUDY DESIGN, SIZE, DURATION

An international meeting with representatives from expert scientific societies involved in FP was held in Barcelona, Spain, in June 2015.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Twenty international FP experts belonging to the American Society of Reproductive Medicine, ESHRE and the International Society of Fertility Preservation reviewed the literature up to June 2015 to be discussed at the meeting, and approved the final manuscript. At the time this manuscript was being written, new evidence considered relevant for the debated topics was published, and was consequently included.

MAIN RESULTS AND THE ROLE OF CHANCE

Several oncological and non-oncological diseases may affect current or future fertility, either caused by the disease itself or the gonadotoxic treatment, and need an adequate FP approach. Women wishing to postpone maternity and transgender individuals before starting hormone therapy or undergoing surgery to remove/alter their reproductive organs should also be counselled accordingly. Embryo and oocyte cryopreservation are first-line FP methods in postpubertal women. Metaphase II oocyte cryopreservation (vitrification) is the preferred option. Cumulative evidence of restoration of ovarian function and spontaneous pregnancies after ART following orthotopic transplantation of cryopreserved ovarian tissue supports its future consideration as an open clinical application. Semen cryopreservation is the only established method for FP in men. Testicular tissue cryopreservation should be recommended in pre-pubertal boys even though fertility restoration strategies by autotransplantation of cryopreserved testicular tissue have not yet been tested for safe clinical use in humans. The establishment of international registries on the short- and long-term outcomes of FP techniques is strongly recommended.

LIMITATIONS, REASONS FOR CAUTION

Given the lack of studies in large cohorts or with a randomized design, the level of evidence for most of the evidence reviewed was 3 or below.

WIDER IMPLICATIONS OF THE FINDINGS

Further high quality studies are needed to study the long-term outcomes of FP techniques.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

N/A.

The Effect of Erythropoietin in Preventing Ischemia-Reperfusion Injury in Ovarian Tissue Transplantation

Condensation Erythropoietin improved the survival of follicles in ovarian grafts most likely by reducing ischemic injury, by improving neoangiogenesis, and by its antioxidant effects.

OBJECTIVE

Ovarian tissue cryopreservation and transplantation are the only options accepted for prepubertal girls and women requiring immediate chemotherapy. Ischemia-reperfusion injury is the main obstacle for ovarian tissue transplantation. In the present study, we aimed to evaluate the effects of recombinant human erythropoietin (EPO) on tissue viability in autotransplanted rat ovaries.

STUDY DESIGN

Seventeen female rats were randomized into 3 groups as sham control group (n = 5), EPO-treated group (n = 6), and EPO-untreated group (n = 6). Both ovaries were excised and transplanted into a subcutaneous pouch formed at the anterior abdominal wall in the EPO-treated and untreated groups. In the EPO group, 5000 U/kg EPO was applied as local injection to the site that ovarian tissue was placed and the dose was repeated with the same route at the end of the fourth week. After 2 months, ovaries were removed and blood samples were obtained. Levels of estradiol (E₂), vascular endothelial growth factor (VEGF), VEGF-C, and lipid hydroperoxidase (LPO) and the activity of glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase (CAT) were measured both in blood and tissue samples. Histopathological and morphometric analyses were also performed on tissue samples.

RESULTS

Considering serum levels, mean CAT was significantly higher ( P = .003) and mean SOD ( P = .033), LPO ( P = .050), VEGF ( P = .001), and VEGF-C ( P = .024) were significantly lower in the EPO-treated group than in the untreated group. Mean serum GPX levels were similar. Significantly higher levels of E₂ were determined in the EPO group than in the untreated group. Highest serum E₂ levels were found in the sham group ( P = .001). Tissue levels of GPX (1.23) and CAT (53.17) were significantly higher in the EPO group ( P = .002 and P = .001, respectively). However, tissue levels of SOD and LPO, VEGF, and VEGF-C levels were significantly lower in the EPO group than those in the untreated group ( P = .033, P = .050, P = .002, and P = .003, respectively). In tissue examination, the highest values of x, y axis and epithelial height were in the sham group. Mean value of the EPO group was found statistically significantly higher than that of the untreated group ( P ≤ .05). In terms of antral follicle count, ordering was found as sham > EPO-treated > EPO-untreated group. Follicle counts in the EPO group were significantly higher than those in the untreated group ( P ≤ 0.05).

CONCLUSION

Erythropoietin improved the survival of follicles in ovarian grafts most likely by reducing ischemic injury, by improving neoangiogenesis, and by its antioxidant effects.

Ovarian tissue cryopreservation: a committee opinion

Ovarian tissue cryopreservation is an option to preserve reproductive potential in patients who must urgently undergo aggressive chemotherapy and/or radiotherapy or who have other medical conditions requiring treatment that may threaten ovarian function and subsequent fertility. Ovarian tissue cryopreservation may be the only option available to prepubertal girls undergoing such treatments. However, these techniques are still considered to be experimental. This document outlines the current technology, clinical outcomes, and risks of ovarian tissue cryopreservation and recommendations for clinical applications. This document and the document "Mature Oocyte Cryopreservation: A Guideline" published in 2013 (Fertil Steril 2013;99:37-43) replace the document "Ovarian Tissue and Oocyte Cryopreservation" last published in 2008 (Fertil Steril 2008;90:S241-6).

Regulation of follicle growth and apoptosis in cultured mouse ovaries by NGF and oxygen

Cryopreservation of ovarian tissue has been proposed for use in preserving female fertility before anticancer chemo-radiotherapy, because ovarian tissue contains a large pool of non-growing, primordial follicles. The mechanisms that regulate the exit of follicles from the pool are poorly understood. To determine optimal conditions for in vitro ovarian culture, we investigated the effects of nerve growth factor (NGF) and oxygen concentration on follicle growth and apoptosis. Oxygen concentration affected both cell proliferation and apoptosis. Under 20% oxygen, but not 1.5% or 5%, NGF decreased apoptosis in mouse ovaries by down-regulating the pro-apoptotic genes Bax and p53. In conclusion, high oxygen tension during in vitro ovarian culture promotes follicle growth and, in conjunction with NGF, suppresses apoptosis. The efficiency of this method to preserve fertility depends in part on the level of atresia. These results suggest that oxygen and NGF may be used to increase numbers of preantral follicles and mature oocytes in the culture of mammalian ovarian cortical strips.

Beneficial effect of hyperbaric oxygen therapy on the follicular survival in the mouse ovary after transplantation

A large proportion of follicles are lost during the initial ischemia that occurs after transplantation of ovarian tissues. Thus, the effect of hyperbaric oxygen therapy (HBO) on the follicular loss of ovarian tissues after transplantation was examined in mice. Ovarian slices from ICR mice were transplanted under the kidney capsule in ovariectomized ICR. Hyperbaric oxygen with 100% oxygen was initiated for 30 min at 2.5 atmospheres absolute immediately after transplantation, and this treatment was repeated at 48-h intervals for 2 weeks. The number of follicles was dramatically reduced at 2 weeks post transplantation. However, HBO was significantly effective in enhancing the survival of transplanted ovarian follicles. The survival rates of primordial and primary follicles in ovarian tissues of mice with HBO were significantly higher than those without HBO. These results indicate HBO can be effectively used for the enhancement of survival of transplanted ovarian tissues.

Examination of viability and quality of ovarian tissue after cryopreservation using simple laboratory methods in ewe

BACKGROUND

The objective of the present study is to assess viability tests and to evaluate follicle ovarian tissue quality after freezing-thawing procedures.

METHODS

Ewe's ovaries were harvested at the slaughterhouse, after dissection each ovarian specimen was divided into two groups: fresh tissue (control group) and frozen tissue.In the first part of the study, the follicles viability was assessed by trypan blue staining, calcein AM/ethidium homodimer-1 staining (LIVE/DEAD viability/cytotoxicity kit, Molecular Probes) and morphology in the two groups. In the second part of the study the quality of the whole ovarian tissue was evaluated by the quantification of the release of lactate dehydrogenase measurement (Cytotoxicity Detection kit ROCHE), DNA fragmentation by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling (TUNEL) in primordial and primary follicles (ApopDETEK Kit system Enzo) and morphology in the two groups. 100 Follicles (primordial and primary) were counted on both fresh and frozen hemiovary to assess this various tests.

RESULTS

Ovarian follicle viability assessment was similar using trypan blue or calcein/ethidium staining. Follicles showed a decreased viability after freezing-thawing.After cryopreservation, a significant correlation between the percentage of normal follicles and viability rate was found using trypan blue (r=0.82, p<0.05) or calcein AM/ethidium homodimer-1 staining (r=0.76, p<0.05). Increased cytotoxicity showed by enhancement of LDH release was found after cryopreservation (21.60+/-1.1% vs 52.2+/-7.7%). A significant negative correlation between the percentage of morphologically normal follicles and cytotoxicity was observed. No significant difference in DNA fragmentation rate between frozen and control groups was found (26±8.2% vs 38±4.5%).

CONCLUSION

We suggest the use of trypan blue staining for the histological assessment of viability, the use of LDH assay for the cytotoxicity assessement and finally the use of DNA fragmentation assessment to valid different freezing-thawing protocols.

Mouse ovarian follicle cryopreservation using vitrification or slow programmed cooling: assessment of in vitro development, maturation, ultra-structure and meiotic spindle organization

AIM

To compare different outcomes of vitrification and slow freezing of isolated pre-antral follicles and to evaluate different cryo-devices for vitrification of isolated follicles.

METHODS

Pre-antral follicles were isolated from mouse ovaries and cryopreserved using vitrification and slow freezing. A preliminary experiment was carried out to select the optimal cryo-device for vitrification of isolated follicles. A total of 414 follicles were randomly distributed among four groups: control (CT) fresh (n=100), nylon mesh (n=96), electron microscopy grid (n=102), and micro-capillary tips (n=116). Subsequently, a total of 979 follicles were randomly assigned to three different groups: CT fresh (n=256), vitrification (n=399) and slow freezing (n=324). CT and cryopreserved/thawed follicles were cultured in vitro and examined daily for development. Final maturation was triggered with human chorionic gonadotrophin and rates of oocyte maturation were calculated. The ultra-structure of cryopreserved/thawed follicles was studied using electron microscopy. Meiotic spindle presence and organization in mature oocytes were examined using the Oosight imaging system.

RESULTS

  Micro-capillary tips resulted in poor immediate post-warming survival but no differences were observed in the subsequent in vitro development characteristics between different cryo-devices. Nylon mesh proved to be the easiest carrier, particularly when large numbers of follicles were to be vitrified. Compared to vitrification, slow freezing resulted in a significantly lower number of intact follicles at the end of the culture period (P<0.0001). However all other outcome measures were comparable between both techniques.

CONCLUSIONS

Isolated follicles were more vulnerable to cryodamage after slow freezing as compared to vitrification.

Granulocyte colony-stimulating factor in conjunction with vascular endothelial growth factor maintains primordial follicle numbers in transplanted mouse ovaries

OBJECTIVE

To determine whether granulocyte colony-stimulating factor (G-CSF), stem cell factor (SCF), or vascular endothelial growth factor (VEGF) improve the outcome of ovarian grafting.

DESIGN

Experimental animal study.

SETTING

Tertiary care hospital, animal facilities.

ANIMAL(S)

Young adult (6- to 8-week-old) C57BL/6 female mice.

INTERVENTION(S)

Orthotopic transplantation of the frozen-thawed ovary. Group 1 (n = 6) received VEGF (8 g/kg/day); group 2 (n = 6) received VEGF and G-CSF (50 g/kg/day), group 3 (n = 6) received G-CSF and SCF (100 g/kg/day), and group 4 (n = 5) received saline (vehicle controls). All injections were given once daily for 5 days starting the day after surgery. Ovaries were collected 2 weeks after transplantation.

MAIN OUTCOME MEASURE(S)

Number of nonatretic immature (primordial, primary, and small preantral) follicles.

RESULT(S)

Transplanted ovaries in mice injected with VEGF concurrently with G-CSF maintained a statistically significantly larger pool of primordial follicles compared with transplanted ovaries in saline-injected controls. Follicle numbers (total immature and primordial) in transplanted ovaries showed no statistically significant difference in mice injected with VEGF alone or G-CSF plus SCF compared with saline-injected controls.

CONCLUSION(S)

After ovarian transplantation, mice treated with VEGF and G-CSF maintain a significantly greater number of primordial follicles compared with the transplanted ovaries in control animals, suggesting that the combination of G-CSF and VEGF minimizes ischemic damage and thus improves the viability and function of the ovarian graft.

Which are the ideal donor and recipient vessels for a whole ovarian transplantation?

OBJECTIVE

To compare deep circumflex iliac (DCI) and deep inferior epigastric (DIE) pedicles as potential recipient vessels for a whole ovarian microvascular transplantation.

DESIGN

Anatomical study.

SETTING

Laboratory of anatomy, university center.

PATIENT(S)

Ten fresh human female cadavers.

INTERVENTION(S)

Anatomical dissections, vascular injections, histologic analysis.

MAIN OUTCOME MEASURE(S)

Morphological analysis of the gonadic, DCI, and DIE pedicles; diameter of the vessels at regular intervals along their entire length. Comparisons of the caliber values between receiving (DCI and DIE) and gonadic pedicles aiming to determine the optimal size match.

RESULT(S)

We highlight a tortuous appearance of the gonadic artery. This morphology contrasted with the venous system that included two or three straight veins, one of them being wider than the others. The gonadic vessels converge into a wider artery and vein at 5 cm from the ovary. An optimal size match existed between gonadic and DCI arteries and veins sections, in 13 of 14 gonadic pedicles.

CONCLUSION(S)

A safe microsurgical whole ovarian transplantation is feasible if the gonadic pedicle is harvested with a minimal length of 5 cm from the ovary. The DCI pedicle seems to have the best size match with the ovarian vessels to perform a reliable end-to-end microvascular anastomosis.

Clinical grade vitrification of human ovarian tissue: an ultrastructural analysis of follicles and stroma in vitrified tissue

BACKGROUND

Cancer therapy is one of many conditions which may diminish the ovarian reserve. Banking of human ovarian tissue has become an option for the preservation of female fertility. We have shown that vitrification is an excellent method to cryopreserve ovarian tissue. To carry out vitrification in a clinical setting, we have developed a clinical grade closed system to avoid direct contact of ovarian tissue with liquid nitrogen.

METHODS

Ovarian tissue was obtained by biopsy from 12 consenting women undergoing Caesarean section. Tissues were vitrified in cryotubes, using dimethyl sulphoxide, 1,2-propanediol, ethylene glycol and polyvinylpyrrolidon as cryoprotectants. Non-vitrified and warmed-vitrified tissue was compared by light and electron microscopic morphology of the follicles within the tissues.

RESULTS

We did not see any differences in the light or electron microscopic ultrastructure of oocytes between non-vitrified and vitrified tissues. No irreversible subcellular alterations in vitrified tissues were seen.

CONCLUSIONS

The ultrastructure of follicles within the vitrified human ovarian tissue was well preserved using cryotube in a closed vitrification system to avoid direct contact of liquid nitrogen. The system is compatible with the European tissue directive.

Successful cryoloop vitrification and subsequent in vitro maturation of mouse preantral follicles

The purpose of this study was to assess follicular viability and competence through in vitro maturation (IVM) of cryoloop vitrified mouse preantral follicles. Early mouse preantral follicles were isolated and vitrified using the cyroloop vitrification technique. After thawing, the preantral follicles and oocytes were cultured and in vitro matured for 10 d to the metaphase two stage (M2). Oocytes were assessed for viability at 2 and 10 d of IVM and compared to a control group of freshly isolated preantral follicles undergoing IVM. Of vitrified follicles, 94.0% (345/367) were recovered after thawing. The survival rate after the first two-days of IVM culture was 82.3% (284/345) for the cryoloop vitrified follicles and 100% for the control follicles (437/437). The percentage of oocytes in the cryoloop group that developed to M2 was 70.2% (174/248), comparable to that of the control group at 68.7% (241/351) (p value 0.12). Our results indicate that cyroloop vitrification is a viable and practical technique for cryopreservation of mouse preantral follicles. Human oocyte cryopreservation by means of cryoloop vitrification may prove to be useful as a possible treatment modality for human fertility preservation.

Reproduction after breast cancer

Breast cancer is the most frequently occurring cancer in women of developed countries, and as a result of new developments in breast cancer treatment, more women are cured after being diagnosed with this disease. It is important that fertility preservation strategies are addressed before chemotherapy, because chemotherapy may induce premature ovarian failure (depending on the woman's age, the drugs used, the dosage and duration of treatment). Among possible solutions are embryos or oocytes cryopreservation, ovarian tissue cryopreservation-freezing with a subsequent orthotopic and heterotopic autotransplantation, whole ovary cryopreservation, ovarian suppression with gonadotropin-releasing hormone (GnRH) analogues, which inhibit ovarian follicular depletion induced by chemotherapeutic agents and in vitro fertilisation (IVF) after ovulation induction with aromatase inhibitors or tamoxifen.

Preserving female fertility following cancer treatment: current options and future possibilities

Children and women of reproductive age are increasingly surviving cancer diagnoses, and therefore long-term quality-of-life issues are of greater importance at the time of diagnosis. Cancer therapies including radiation and chemotherapy can be detrimental to fertility, and therefore many patients are motivated to preserve fertility prior to cancer treatment. The only highly successful method in preserving fertility to date is embryo cryopreservation, which may not be appropriate for some patients due to age, delay in treatment, cancer type and stage, as well as availability of an acceptable sperm donor. Alternative methods including oocyte cryopreservation and ovarian tissue banking may also preserve fertility while providing additional flexibility to patients. In vitro ovarian follicle maturation following tissue banking is one potential approach that would not require a delay in cancer therapy for ovarian stimulation, would not require an immediate sperm donor, and does not carry the risk of reintroducing malignant cells following tissue transplantation. In vitro follicle culture systems have resulted in successful live births in the mouse. However, many challenges must be addressed in translating the system to the human. This review summarizes current approaches to fertility preservation and discusses recent developments and future challenges in developing a human in vitro follicle culture system.

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.

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.

[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.

Successful pregnancy in ovariectomized mice using a combination of heterotopic autotransplantation of ovarian tissues and embryo transfer

Aim:  The present report is the first to show that, after ovariectomy, female mice with autotransplanted ovarian sections can maintain pregnancy after embryo transfer (ET) independent of the transplantation site. Methods:  Three-month-old ICR females were ovariectomized, and sections from their own ovaries were transplanted either under their kidney capsule (KC group) or into a subcutaneous space (SC group) just after ovariectomy. In vitro fertilized blastocysts were transferred into uterine horns of the pseudopregnant mice that had received the transplanted ovarian tissues. Cesarean sections were carried out 17 days after ET to deliver any live fetuses that were present, and the numbers of implantation sites and fetuses were noted. Transplanted ovarian sections were removed and fixed for histological analysis. Results:  Of the 10 mice in the KC group that received 107 blastocysts, two females (20%) became pregnant; they showed 12 implantation sites (11.2%) and produced four pups (3.7%). In the SC group, 101 blastocysts were transferred to eight females, and three females (37.5%) became pregnant; there were seven implantation sites (6.9%), and three pups (3.0%) were born. There were no statistically significant differences between the two groups in any of the parameters evaluated. On histological examination, luteinization and vascularization of the ovarian sections that were transplanted in the pregnant SC and KC females were noted. Conclusion:  The pregnancy and full-term fetal development were obtained in ovariectomized mice using a combination of heterotopic ovarian tissue autotransplantation and transfer of embryos produced by in vitro fertilization.

Membrane Transport Properties of Equine and Macaque Ovarian Tissues Frozen in Mixtures of Dimethylsulfoxide and Ethylene Glycol

The rate at which equine and macaque ovarian tissue sections are first cooled from +25°Cto+4°C has a significant effect on the measured water transport when the tissues are subsequently frozen in 0.85M solutions of glycerol, dimethylsulfoxide (DMSO), or ethylene glycol (EG). To determine whether the response of ovarian tissues is altered if they are suspended in mixtures of cryoprotective agents (CPAs), rather than in solutions of a single CPA, we have now measured the subzero water transport from ovarian tissues that were suspended in mixtures of DMSO and EG. Sections of freshly collected equine and macaque ovaries were suspended either in a mixture of 0.9M EG plus 0.7M DMSO (equivalent to a mixture of ∼5%v∕v of EG and DMSO) or in a 1.6M solution of only DMSO or only EG. The tissue sections were cooled from +25°Cto+4°C and then frozen to subzero temperatures at 5°C∕min. As the tissues were being frozen, a shape-independent differential scanning calorimeter technique was used to measure water loss from the tissues and, consequently, the best fit membrane permeability parameters (Lpg and ELp) of ovarian tissues during freezing. In the mixture of DMSO+EG, the respective values of Lpg and ELp for equine tissue first cooled at 40°C∕min between +25°C and +4°C before being frozen were 0.15μm∕minatm and 7.6kcal∕mole. The corresponding Lpg and ELp values for equine tissue suspended in 1.6M DMSO were 0.12μm∕minatm and 27.2kcal∕mole; in 1.6M EG, the values were 0.06μm∕minatm and 21.9kcal∕mole, respectively. For macaque ovarian tissues suspended in the mixture of DMSO+EG, the respective values of Lpg and ELp were 0.26μm∕minatm and 26.2kcal∕mole. Similarly, the corresponding LLg and ELp values for macaque tissue suspended in 1.6M DMSO were 0.22μm∕minatm and 31.4kcal∕mole; in 1.6M EG, the values were 0.20μm∕minatm and 27.9kcal∕mole. The parameters for both equine and macaque tissue samples suspended in the DMSO+EG mixture and first cooled at 0.5°C∕min between +25°C and +4°C were very similar to the corresponding values for samples cooled at 40°C∕min. In contrast, the membrane parameters of equine and macaque samples first cooled at 0.5°C∕min in single-component solutions were significantly different from the corresponding values for samples cooled at 40°C∕min. These results show that the membrane properties of ovarian cells from two species are different, and that the membrane properties are significantly affected both by the solution in which the tissue is suspended and by the rate at which the tissue is cooled from +25°Cto+4°C before being frozen. These observations suggest that these variables ought to be considered in the derivation of methods to cryopreserve ovarian tissues.

Fertility preservation options for women with malignancies

Cancer is not rare in younger women. There has been a remarkable improvement in the survival rates due to progress in cancer treatment. The necessary treatment for most of the common cancer types occurring in younger women implies either removal of the reproductive organs or cytotoxic treatment that could partially or definitively affect reproductive function. Early loss of ovarian function not only puts the patients at risk for menopause-related complications at a very young age, but is also associated with loss of fertility. Further, women in the western hemisphere have been delaying initiation of childbearing to later in life. The results of these changes have led to an increase in patients facing the risk of premature ovarian failure, and therefore seeking help in preserving their fertility. This increase in demand has resulted in a proliferation of techniques to preserve fertility. Indeed, the number of options is increasing; some are more established procedures, such as embryo cryopreservation, and some are still experimental, such as ovarian cryopreservation. Because of the variations in type and dose of chemotherapy, the type of cancer, the time available before onset of treatment, the patient's age and the partner status, each case is unique and requires a different strategy of fertility preservation.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to recall the potential early loss of ovarian function secondary to radiotherapy and/or chemotherapy for cancer at a young age; explain the increasing demands for fertility preservation; and summarize the limited number of proven, safe, and efficacious methods.

Apoptosis and ultrastructural assessment after cryopreservation of whole human ovaries with their vascular pedicle

OBJECTIVE

To investigate possible damage caused by freeze-thawing whole human ovaries.

DESIGN

Prospective experimental study.

SETTING

Academic gynecology research unit in a university hospital.

PATIENT(S)

Ovaries were obtained from three women (aged 29-36 years).

INTERVENTION(S)

Ovaries were perfused and bathed in cryoprotective solution, and slow freezing was performed. Rapid thawing was achieved by perfusion and bathing with a decreased sucrose gradient.

MAIN OUTCOME MEASURE(S)

Apoptosis was assessed by the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphates nick end-labeling (TUNEL) method and by immunohistochemistry for active caspase-3 in fresh ovaries, after cryoprotectant exposure, and after thawing. Morphometric analysis of TUNEL-positive surface area was performed. Ultrastructure was assessed by transmission electron microscopy (TEM) in the thawed tissue.

RESULT(S)

No primordial or primary follicles were found to be positive for either TUNEL or active caspase-3. No statistically significant difference in mean TUNEL-positive surface area values was found between the three groups: fresh, 0.05% +/- 0.03%, with 134 high-power fields (HPFs); cryoperfused, 0.02% +/- 0.01%, with 130 HPFs; and thawed, 0.09% +/- 0.03%, with 622 HPFs. By means of TEM, follicles and vessels showed a well-preserved ultrastructure, with 96.7% (29/30) healthy-looking primordial and primary follicles, and 96.3% (180/187) healthy-looking endothelial cells.

CONCLUSION(S)

Cryopreservation of intact human ovary with its vascular pedicle, according to the freeze-thawing protocol described here, is not associated with any signs of apoptosis or ultrastructural alterations in any cell types. Whole-organ vascular transplantation may thus be a viable option in the future.

Subzero water transport characteristics and optimal rates of freezing rhesus monkey (Macaca mulatta) ovarian tissue

The purpose of the present study was to examine the effect of two different suprazero (room temperature +25 degrees C to +4 degrees C) cooling conditions on the measured water transport response of primate (Macaca mulatta) ovarian tissue in the presence and absence of cryoprotective agents (CPAs). Freshly collected Macaca mulatta (rhesus monkey) ovarian tissue sections were cooled at either 0.5 degrees C/min or 40 degrees C/min from 25 to 4 degrees C. A shape independent differential scanning calorimeter (DSC) technique was then used to measure the volumetric shrinkage during freezing of ovarian tissue sections at a freezing rate of 5 degrees C/min in the presence and absence of three different CPAs (0.85 M glycerol, 0.85 M dimethylsulfoxide, and 0.85 M ethylene glycol). Thus, water transport during freezing of primate ovarian tissue was obtained at eight different conditions (i.e., at four different freezing media with two different suprazero cooling conditions). The water transport response of ovarian tissue cooled rapidly from 25 to 4 degrees C was significantly different (P < 0.01) than that of slow cooled tissue, in the freezing media without CPAs and with dimethylsulfoxide. However, the differences in the measured water transport response due to the imposed suprazero cooling conditions were reduced with the addition of glycerol and ethylene glycol (statistically different with P < 0.05). By fitting a model of water transport to the experimentally obtained volumetric shrinkage data the best-fit membrane permeability parameters (L(pg) and E(Lp)) were determined. The best-fit parameters of water transport in primate ovarian tissue sections ranged from: L(pg) = 0.7 to 0.15 microm/min-atm and E(Lp) = 22.1 to 32.1 kcal/mol (the goodness of fit parameter, R(2) > 0.96). These parameters suggest that the "optimal rates of cryopreservation" for ovarian tissue are significantly dependent upon suprazero cooling conditions and the choice of CPA.

Ovarian tissue cryopreservation and transplantation: a review

The review covers current options for ovarian tissue cryopreservation and transplantation and provides a systematic review of the existing literature from the last 10 years, taking into account all previously published reviews on the subject. The different cryopreservation options available for fertility preservation in cancer patients are embryo cryopreservation, oocyte cryopreservation and ovarian tissue cryopreservation. The choice depends on various parameters: the type and timing of chemotherapy, the type of cancer, the patient's age and the partner status. The different options and their results are discussed, as well as their putative indications and efficacy. The review concludes that advances in reproductive technology have made fertility preservation techniques a real possibility for patients whose gonadal function is threatened by premature menopause, or by treatments such as radiotherapy, chemotherapy or surgical castration.

[Ovarian cryopreservation: clinical and ethical problems arisen further to study on cases of ovarian cryopreservation]

OBJECTIVE

An early ovarian failure and sterility, on patients often still young, may result from some of the anticancerous treatments. Ovarian cryopreservation is a research way for fertility restoration on patients who will have gonadotoxic treatment. The aim of our work was to study the cases of ovarian tissue preserved in our Department, enabling us to assess the clinical and ethical problems of this technique.

PATIENTS AND METHODS

A retrospective study was conducted from January 2001 onwards up to October 2005, on 14 patients, whose ovarian cortex was frozen our the University Fertility Center (Hôpital de la Conception, Marseille, France).

RESULTS

In our study, the patients' average age was 17+/-5.5 and the median was 14 years [13-24]. Eight patients were under 18 (11+/-3-years-old). The cryopreservation indications were especially haematological (N = 9). More than half of the patients (N = 8) had undergone a gonadotoxic treatment before ovarian cryopreservation.

DISCUSSION AND CONCLUSION

Ovarian cryopreservation is still a recent technology in reproductive medicine. The future of ovarian tissue after thawing, with its different techniques of autograft, is still not consensual. Experimental research remains essential to improve the freezing protocols and ovarian transplant in human medicine.

Suprazero cooling conditions significantly influence subzero permeability parameters of mammalian ovarian tissue

To model the cryobiological responses of cells and tissues, permeability characteristics are often measured at suprazero temperatures and the measured values are used to predict the responses at subzero temperatures. The purpose of the present study was to determine whether the rate of cooling from +25 to +4 degrees C influenced the measured water transport response of ovarian tissue at subzero temperatures in the presence or absence of cryoprotective agents (CPAs). Sections of freshly collected equine ovarian tissue were first cooled either at 40 degrees C/min or at 0.5 degrees C/min from 25 to 4 degrees C, and then cooled to subzero temperatures. A shape-independent differential scanning calorimeter (DSC) technique was used to measure the volumetric shrinkage during freezing of equine ovarian tissue sections. After ice was induced to form in the extracellular fluid within the specimen, the sample was frozen from the phase change temperature to -50 degrees C at 5 degrees C/min. Replicate samples were frozen in isotonic medium alone or in medium containing 0.85 M glycerol or 0.85 M dimethylsulfoxide. The water transport response of ovarian tissue samples cooled at 40 degrees C/min from 25 to 4 degrees C was significantly different (confidence level >95%) from that of tissue samples cooled at 0.5 degrees C/min, whether in the presence or absence of CPAs. We fitted a model of water transport to the experimentally-derived volumetric shrinkage data and determined the best-fit membrane permeability parameters (L(pg) and E(Lp)) of equine ovarian tissue during freezing. Subzero water transport parameters of ovarian tissue samples cooled at 0.5 degrees C/min from 25 to 4 degrees C ranged from: L(pg) = 0.06 to 0.73 microm/min.atm and E(Lp) = 6.1 to 20.5 kcal/mol. The corresponding parameters of samples cooled at 40 degrees C/min from 25 to 4 degrees C ranged from: L(pg) = 0.04 to 0.61 microm/min.atm and E(Lp) = 8.2 to 54.2 kcal/mol. Calculations made of the theoretical response of tissue at subzero temperatures suggest that the optimal cooling rates to cryopreserve ovarian tissue are significantly dependent upon suprazero cooling conditions.

Restoration of ovarian function after orthotopic (intraovarian and periovarian) transplantation of cryopreserved ovarian tissue in a woman treated by bone marrow transplantation for sickle cell anaemia: Case report

Ovarian function after orthotopic transplantation of cryopreserved ovarian tissue has been restored in women with malignant disease. Here the techniques are adapted for a non-cancer patient. In 1999, right oophorectomy was performed in a 21 year old woman before chemotherapy, prior to bone marrow transplantation. Ovarian cortex was frozen, according to a strict protocol. After thawing, ovarian cortex was reimplanted into the ovary and in a peritoneal window close to the ovary in 2004. Four-and-a-half months after reimplantation, LH, FSH, 17beta-estradiol and progesterone levels, as well as ultrasonography, demonstrated the presence of an ovulatory cycle. After this cycle, the patient experienced two other ovulatory cycles, evidenced by FSH and 17beta-estradiol concentrations, as well as ultrasound demonstration of a follicle. Follicular development was clearly observed in both the intraovarian site (1st and 2nd cycle) and the peritoneal window (3rd cycle). Restoration of endocrine ovarian function occurred after ovarian cortical strips, biopsied and cryopreserved before chemotherapy, were reimplanted into the ovary itself and a periovarian peritoneal window.