Obstetric and perinatal outcome in 200 infants conceived from vitrified oocytes

[Vitrification: Principles and results]

Sperm and embryos cryopreservation is a commonly applied technique for several years. Recently authorized in France, vitrification tends to replace gradually the conventional technique of slow freezing, so upsetting the practices in the management of patients. It allows from now on the cryopreservation of oocytes and opens new perspectives in egg donation either still in fertility preservation. This review thus attempted to examine the contribution of vitrification in the freezing of oocytes and human embryos at various stages of development. If obviously vitrification appears as the current method of choice for the cryopreservation of oocytes as well as blastocysts, the results are less cut as regards embryos to early stages. No increase in adverse obstetric and perinatal outcomes in children conceived from vitrified oocytes or embryos is noted in the literature.

Assessment of aneuploidy formation in human blastocysts resulting from cryopreserved donor eggs

Background

Increased embryo implantation rates were reported after transfer of euploid embryos selected by preimplantation genetic screening (PGS). Egg cryopreservation by vitrification has become one of the most important assisted human reproduction technologies. Although reports indicate that development and implantation of human embryos derived from frozen donor eggs are comparative to fresh eggs, it is still unknown whether egg vitrification increases chromosomal abnormalities in eggs, which in turn causes formation of embryonic aneuploidy. Therefore, in this study, we evaluated the aneuploidy formation in the blastocysts derived from frozen donor eggs and also evaluated the efficiency of egg vitrification as an advanced technology for egg cryopreservation.

Results

In this study, donated human eggs from young women were cryopreserved by vitrification and PGS was performed in the resulted blastocysts by DNA microarray. A total of 764 frozen eggs from 75 egg thawing cycles were warmed and 38 blastocysts were biopsied for PGS before embryo transfer. A 97.1% of egg survival rate was obtained and 59.1% of embryos developed to blastocyst stage. After biopsy and PGS, it was found that 84.2% of blastocysts were euploid and 15.8% were aneuploid. Aneuploidy rates varied among donors. Transfers of blastocysts without PGS resulted in higher clinical pregnancy and implantation rates as compared with transfer of blastocysts with PGS.

Conclusions

Although the overall aneuploidy rate was low in the blastocysts derived from frozen donor eggs, high aneuploidy rates were observed in the embryos resulting from some donated eggs. Clinical pregnancy rate was not improved by PGS of embryos resulting from donor eggs, indicating that PGS may not be necessary for embryos derived from donor eggs in most cases.

Electronic supplementary material

The online version of this article (doi:10.1186/s13039-015-0117-8) contains supplementary material, which is available to authorized users.

Comparative efficiency study of fresh and vitrified oocytes in egg donation programs for different controlled ovarian stimulation protocols

The aim of this study was to compare the efficacy when using vitrified and fresh eggs depending on the applied controlled ovarian stimulation protocols in egg donation programs. Study results showed that the controlled ovarian stimulation protocol does not affect the outcome of IVF/ICSI. Vitrification provided survival and pregnancy rates similar to the fresh donor oocyte ones.

Ultrastructure of immature and mature human oocytes after cryotop vitrification

In vitro maturation of vitrified immature germinal vesicle (GV) oocytes is a promising fertility preservation option. We analyzed the ultrastructure of human GV oocytes after Cryotop vitrification (GVv) and compared it with fresh GV (GVc), fresh mature metaphase II (MIIc) and Cryotop-vitrified mature (MIIv) oocytes. By phase contrast microscopy and light microscopy, the oolemmal and cytoplasmic organization of fresh and vitrified oocytes did not show significant changes. GVv oocytes showed significant ultrastructural alterations of the microvilli in 40% of the samples; small vacuoles and occasional large/isolated vacuoles were abnormally present in the ooplasm periphery of 50% of samples. The ultrastructure of nuclei and mitochondria-vesicle (MV) complexes, as well as the distribution and characteristics of cortical granules (CGs), were comparable with those of GVc oocytes. MIIv oocytes showed an abnormal ultrastructure of microvilli in 30% of the samples and isolated large vacuoles in 70% of the samples. MV complexes were normal, but mitochondria-smooth endoplasmic reticulum aggregates appeared to be of reduced size. CGs were normally located under the oolemma but presented abnormalities in distribution and matrix electron density. In conclusion, Cryotop vitrification preserved main oocyte characteristics in the GV and MII stages, even if peculiar ultrastructural alterations appeared in both stages. This study also showed that the GV stage appears more suitable for vitrification than the MII stage, as indicated by the good ultrastructural preservation of important structures that are present only in immature oocytes, like the nucleus and migrating CGs.

Birth and perinatal outcomes and complications for babies conceived following ART

Children born after assisted reproductive techniques (ART) have an increased risk of several adverse perinatal outcomes compared with their naturally conceived peers. This has various causes such as higher multiple birth rates, parental characteristics and higher maternal age, with more being nulliparous. Furthermore the in-vitro techniques, the controlled ovarian stimulation, culture media, and possibly additional freezing or vitrification procedures seem to play a role. However, when analyzing the perinatal trends over time, the differences between ART and naturally conceived children appear to have diminished. This is probably due to ART being more accessible and therefore couples have shorter duration of infertility before referral to ART; hence couples are nowadays less reproductively ill than in the past. A refinement of both clinical and laboratory skills during the past three decades of assisted reproduction may be another explanation. However, caution should be taken, as we do not yet know the full consequences of the observed increase in fetal growth and potential epigenetic changes in the early embryonic stages of fetal development.

L’« horloge biologique » des femmes : un modèle naturaliste en question. Les normes et pratiques françaises face à la croissance de l’infertilité liée à l’âge

La croissance de l’infertilité liée à l’âge dans les sociétés industrielles avancées suscite un accroissement de demandes en matière d’assistance médicale à la procréation (AMP) et amène ainsi chaque société à s’interroger sur ses normes et pratiques. En France, cette question est un révélateur de la spécificité du modèle bioéthique qui encadre les techniques d’AMP ainsi que de ses tensions et contradictions croissantes. La particularité de ce modèle est de se présenter comme strictement « thérapeutique » et de reposer sur la notion d’« infertilité pathologique ». Or c’est justement la simplicité apparente de cette distinction entre pathologie et convenance que met en question l’infertilité liée à l’âge : elle ouvre vers une approche plus complexe de l’infertilité comme phénomène liant à la fois le somatique et le social. À partir d’une enquête auprès de professionnels qui font face à l’infertilité, nous montrerons la prégnance de ce modèle thérapeutique dans leur pratique. Mais nous verrons également que le contexte sociodémographique contemporain amène à une évolution de la notion même d’infertilité et interroge ce modèle de référence. De plus, l’apparition de nouvelles techniques telles que la congélation ovocytaire renforce la mise en question du modèle bioéthique et amène à penser autrement l’opposition pathologie/convenance sur laquelle il est construit. La question est de savoir si ce modèle saura évoluer vers une vision plus complexe et moins idéologique de l’infertilité, ce qui s’avère être un enjeu important pour la société française dans les années à venir et qui va bien au-delà de l’accès aux techniques favorisant ce dépassement.

Cryopreservation of embryos and oocytes in human assisted reproduction

Both sperm and embryo cryopreservation have become routine procedures in human assisted reproduction and oocyte cryopreservation is being introduced into clinical practice and is getting more and more widely used. Embryo cryopreservation has decreased the number of fresh embryo transfers and maximized the effectiveness of the IVF cycle. The data shows that women who had transfers of fresh and frozen embryos obtained 8% additional births by using their cryopreserved embryos. Oocyte cryopreservation offers more advantages compared to embryo freezing, such as fertility preservation in women at risk of losing fertility due to oncological treatment or chronic disease, egg donation, and postponing childbirth, and eliminates religious and/or other ethical, legal, and moral concerns of embryo freezing. In this review, the basic principles, methodology, and practical experiences as well as safety and other aspects concerning slow cooling and ultrarapid cooling (vitrification) of human embryos and oocytes are summarized.

Live birth using vitrified--warmed oocytes in invasive ovarian cancer: case report and literature review

This article reports the live birth of a healthy newborn using vitrified-warmed oocytes in a young patient with invasive mucinous ovarian carcinoma (stage Ic). Diagnosis was performed after a laparoscopic left adnexectomy. She underwent two cycles of ovarian stimulation, and 14 oocytes were vitrified before fertility-sparing surgery with uterus preservation went ahead. One year later, a transfer of two embryos was performed after insemination of warmed oocytes. Eighteen days after the transfer, she underwent a laparotomy because of abdominal pain, vaginal bleeding and haemoperitoneum. A right cornual ectopic pregnancy in the uterus was diagnosed and a wedge resection was performed to resolve it. One week later, a viable intrauterine pregnancy was confirmed under ultrasound. An elective Caesarean section was performed at week 38 of gestation, resulting in the birth of a healthy boy weighing 2650 g. As far as is known, this is the first live birth reported through vitrified-warmed oocytes in a patient with invasive ovarian cancer. Although oocyte vitrification is an alternative to be considered for fertility preservation in highly selected cases of ovarian cancer, controversial issues are discussed. Fertility preservation is a proven possibility in some cancer patients according to their age, disease and time available until the beginning of their oncological treatment. Although oocyte vitrification is an alternative to be considered for fertility preservation in highly selected cases of ovarian cancer, no live birth has been reported. We report the live birth of a healthy newborn through vitrified-warmed oocytes in a young patient with invasive mucinous ovarian carcinoma (stage Ic). Diagnosis was performed after a laparoscopic left adnexectomy. She underwent two cycles of ovarian stimulation, and 14 oocytes were vitrified before fertility-sparing surgery with uterus preservation went ahead. One year later, a transfer of two embryos was performed after the insemination of the warmed oocytes. Eighteen days after the transfer she underwent a laparotomy because of abdominal pain, vaginal bleeding and haemoperitoneum. A right cornual ectopic pregnancy in the uterus was diagnosed and a wedge resection was performed to resolve it. One week later, a viable intrauterine pregnancy was confirmed under ultrasound. An elective Caesarean section was performed at week 38 of gestation, resulting in the birth of a healthy boy weighing 2650 g. To our knowledge, this is the first live birth reported using vitrified-warmed oocytes in invasive ovarian cancer. Controversial issues are reviewed and discussed.

Fertility issues in cancer survivorship

Breakthroughs in cancer diagnosis and treatment have led to dramatic improvements in survival and the need to focus on survivorship issues. Chemotherapy and radiotherapy can be gonadotoxic, resulting in impaired fertility. Techniques to help cancer survivors reproduce have been improving over the past decade. Discussion of the changes to a patient's reproductive health after cancer treatment is essential to providing comprehensive quality care. The purpose of this review is to aid in pre- and posttreatment counseling, focusing on fertility preservation and other strategies that may mitigate risks to the patient's reproductive, sexual, and overall health.

Oocyte vitrification: advances, progress and future goals

BACKGROUND

Recent advances in vitrification technology have markedly improved the efficacy of oocyte cryopreservation in terms of oocyte survival and pregnancy, as well as live birth rates. However, there still remains room for improvement in terms of vitrification techniques.

OBJECTIVE

The remaining challenges include the development of a less cytotoxic vitrification solution and of a safe vitrification device in order to have vitrification techniques considered as a standard clinical laboratory procedure.

METHODS

A systematic electronic literature search strategy has been conducted using PubMed (Medline) databases with the use of the following key words: oocyte, vitrification, cryoprotectant, preservation, pregnancy, and live birth. A list of published papers focused on the improvement of vitrification techniques to have the vitrification protocol standardized have been evaluated in full text for this review. Only key references were cited.

CONCLUSIONS

Vitrification technology has made significant advancements and holds great promise, but many issues remains to be addressed before it becomes a standardized procedure in clinical laboratories such as the fact that oocyte vitrification may not require a high concentration of cryoprotectant in the vitrification solution when it has a suitable cooling and warming rate. There is also no consistent evidence that indicates the absence of risk to the vitrified oocytes when they are stored for a prolonged period of time in direct-contact with liquid nitrogen. The long-term development of infants born as a result of this technology equally remains to be evaluated.

Vitrification in human and domestic animal embryology: work in progress

According to the analysis of papers published in major international journals, rapidly increasing application of vitrification is one of the greatest achievements in domestic animal and especially human embryology during the first decade of our century. This review highlights factors supporting or hampering this progress, summarises results achieved with vitrification and outlines future tasks to fully exploit the benefits of this amazing approach that has changed or will change many aspects of laboratory (and also clinical) embryology. Supporting factors include the simplicity, cost efficiency and convincing success of vitrification compared with other approaches in all species and developmental stages in mammalian embryology, while causes that slow down the progress are mostly of human origin: inadequate tools and solutions, superficial teaching, improper application and unjustified concerns resulting in legal restrictions. Elimination of these hindrances seems to be a slower process and more demanding task than meeting the biological challenge. A key element of future progress will be to pass the pioneer age, establish a consensus regarding biosafety requirements, outline the indispensable features of a standard approach and design fully-automated vitrification machines executing all phases of the procedure, including equilibration, cooling, warming and dilution steps.

Closed vitrification of mouse oocytes using the CryoLogic vitrification method: A modification that improves developmental competence

Objective

To compare the mouse oocyte vitrification outcomes of the CryoLogic vitrification method (CVM) and the conventional open method using a Cryotop. Two CVM methods (original CVM and modified CVM) were tested.

Methods

Mature oocytes obtained from female BDF-1 mice were vitrified by two-step exposure to equilibrium and vitrification solutions. Three vitrification protocols were tested on three groups: the CVM-kit, modified CVM, and Cryotop groups. After exposure to the two solutions, the oocytes were vitrified. After warming, the oocytes were fertilized in vitro, and the embryo development was assessed. Blastomeres positive for caspase were counted using an in situ assay kit. The spindle morphology and chromosome configurations of warmed vitrified oocytes were also assessed.

Results

The modified CVM and Cryotop groups showed similar developmental capacities, and similar proportions of cells with intact spindles and chromosome configurations. The modified CVM protocol was superior to the original CVM protocol for developmental competence and intact spindle preservation. However, the CVM group showed a relatively higher number of apoptotic cells in blastocysts.

Conclusion

Closed vitrification using the modified CVM protocol may be used as an alternative to the conventional open method, but strategies to decrease apoptosis in the blastomere need to be investigated.

The effect of minimal concentration of ethylene glycol (EG) combined with polyvinylpyrrolidone (PVP) on mouse oocyte survival and subsequent embryonic development following vitrification

PURPOSE

Vitrification techniques employ a relatively high concentration of cryoprotectant in vitrification solutions. Exposure of oocytes to high concentrations of cryoprotectant is known to damage the oocytes via both cytotoxic and osmotic effects. Therefore, the key to successful vitrification of oocytes is to strike a balance between the usage of minimal concentration of cryoprotectant without compromising their cryoprotective actions.

METHODS

The minimal concentration of ethylene glycol (EG) on mouse oocyte survival and subsequent embryonic development was evaluated following vitrification-warming and parthenogenetic activation. Polyvinylpyrrolidone (PVP) combined with EG on mouse oocyte survival and subsequent embryonic development as well as morphology of the spindle and chromosome alignment were also evaluated. Vitrification system was adapted with JY Straw and the cooling rate was approximately 442-500 °C/min. In contrast, the warming rate was approximately 2,210-2,652 °C/min.

RESULTS

Survival rate of oocytes increased significantly when 15 % EG was combined with 2 % PVP in vitrification solution (VS). The effect of combination of EG and PVP was not significant when the concentration of EG was 20 % and higher. Although there were no significant differences in embryonic development, the percentage of abnormal spindle and chromosome alignment was significantly higher in the oocytes without 2 % PVP in VS.

CONCLUSIONS

Our data provide a proof of principle for oocyte vitrification that may not require a high concentration of cryoprotectant. There are synergic effects of EG combined with PVP for oocyte vitrification, which may provide important information to the field in developing less cytotoxic VS.

Optimization of cryoprotectant loading into murine and human oocytes

Loading of cryoprotectants into oocytes is an important step of the cryopreservation process, in which the cells are exposed to potentially damaging osmotic stresses and chemical toxicity. Thus, we investigated the use of physics-based mathematical optimization to guide design of cryoprotectant loading methods for mouse and human oocytes. We first examined loading of 1.5 M dimethyl sulfoxide (Me(2)SO) into mouse oocytes at 23°C. Conventional one-step loading resulted in rates of fertilization (34%) and embryonic development (60%) that were significantly lower than those of untreated controls (95% and 94%, respectively). In contrast, the mathematically optimized two-step method yielded much higher rates of fertilization (85%) and development (87%). To examine the causes for oocyte damage, we performed experiments to separate the effects of cell shrinkage and Me(2)SO exposure time, revealing that neither shrinkage nor Me(2)SO exposure single-handedly impairs the fertilization and development rates. Thus, damage during one-step Me(2)SO addition appears to result from interactions between the effects of Me(2)SO toxicity and osmotic stress. We also investigated Me(2)SO loading into mouse oocytes at 30°C. At this temperature, fertilization rates were again lower after one-step loading (8%) in comparison to mathematically optimized two-step loading (86%) and untreated controls (96%). Furthermore, our computer algorithm generated an effective strategy for reducing Me(2)SO exposure time, using hypotonic diluents for cryoprotectant solutions. With this technique, 1.5 M Me(2)SO was successfully loaded in only 2.5 min, with 92% fertilizability. Based on these promising results, we propose new methods to load cryoprotectants into human oocytes, designed using our mathematical optimization approach.

What do reproductive-age women who undergo oocyte cryopreservation think about the process as a means to preserve fertility?

OBJECTIVE

To better understand women's beliefs, priorities, and attitudes toward oocyte cryopreservation, to appreciate the extent of their reproductive education, and to track the reproductive paths of women who chose to undergo oocyte cryopreservation treatment.

DESIGN

An anonymous 30-question survey.

SETTING

Not applicable.

PATIENT(S)

From 2005-2011, 478 women completed ≥1 oocyte cryopreservation treatment cycle at our center to defer reproduction.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Demographics, motivations, desires, fertility knowledge, and outcomes related to oocyte cryopreservation.

RESULT(S)

A total of 183 patients (38%) completed the survey with >80% being aged ≥35 years; white; having no partner at time of oocyte cryopreservation; undergoing oocyte cryopreservation after an optimal reproductive age; feeling they had improved their reproductive future after oocyte cryopreservation and being empowered by the process; aware of age-related infertility; sensing popular media falsely portrayed the upper age limit for natural conception; and recorded lack of partner as the primary rationale for not yet starting a family. Nineteen percent of respondents added that workplace inflexibility contributed to their reproductive dilemma. Half stated they learned about oocyte cryopreservation from a friend; others became aware through a medical provider, the media, and the internet. Most patients (93%) have not yet returned to use their frozen oocytes; 11 stated they had. Overall, 20% reported a successful conception after oocyte cryopreservation.

CONCLUSION(S)

Surveying oocyte cryopreservation patients provides a glimpse into the knowledge base and motivations surrounding current female reproductive practices. Oocyte cryopreservation technology may prove to bridge the gap between reproductive prime and when a woman is realistically "ready" to have children.

The root of reduced fertility in aged women and possible therapentic options: current status and future perspects

It is well known that maternal ageing not only causes increased spontaneous abortion and reduced fertility, but it is also a high genetic disease risk. Although assisted reproductive technologies (ARTs) have been widely used to treat infertility, the overall success is still low. The main reasons for age-related changes include reduced follicle number, compromised oocyte quality especially aneuploidy, altered reproductive endocrinology, and increased reproductive tract defect. Various approaches for improving or treating infertility in aged women including controlled ovarian hyperstimulation with intrauterine insemination (IUI), IVF/ICSI-ET, ovarian reserve testing, preimplantation genetic diagnosis and screening (PGD/PGS), oocyte selection and donation, oocyte and ovary tissue cryopreservation before ageing, miscarriage prevention, and caloric restriction are summarized in this review. Future potential reproductive techniques for infertile older women including oocyte and zygote micromanipulations, derivation of oocytes from germ stem cells, ES cells, and iPS cells, as well as through bone marrow transplantation are discussed.

Fertility and borderline ovarian tumor: a systematic review of conservative management, risk of recurrence and alternative options

BACKGROUND

The aim of this systematic review was to evaluate the fertility outcome after borderline ovarian tumor (BOT) management and the results of conservative management, risk of recurrence and alternative options.

METHODS

The search strategy was based on relevant terms concerning BOT using Medline and the Central Cochrane Library. Both early and advanced stages of serous and mucinous BOT were included, but not rare entities such as endometrioid, Brenner or clear-cell BOT because of their low incidence. We considered all articles-case reports, original studies, meta-analyses and reviews-in English and French.

RESULTS

Overall, 230 articles were screened of which 120 were retained for review. Most pregnancies were spontaneous but some data were obtained from studies analyzing the contribution of assisted reproductive technology (ART). However, not all studies differentiated spontaneous pregnancy from those obtained after fertility treatment including ovulation induction, intrauterine insemination and IVF. Conservative management of early stage BOT resulted in a pooled estimate for spontaneous pregnancy rate of 54% with a low risk of lethal recurrence (pooled estimate: 0.5%). In patients with advanced stage BOT, the spontaneous pregnancy rates was lower (34% in the single series reporting pregnancy rate in this context) and the risk of lethal recurrence increased (pooled estimate: 2%).

CONCLUSIONS

This systematic review underlines that fertility subsequent to treatment of BOT depends mainly on histology and initial staging to distinguish early from advanced stages. In patients with advanced stage BOT, several alternative options to conservative management are available to allow patients to conceive without compromising their prognosis.

Optimized protocol for cryopreservation of human eggs improves developmental competence and implantation of resulting embryos

Background

Successful egg cryopreservation has many potential benefits to a variety of patients. However, a superior standard protocol describing all aspects of oocyte cryopreservation has not yet been identified. Oocyte cryopreservation is still a technical challenge for many infertility clinics. To maintain satisfactory clinical outcomes, there is a need to develop an easy to use, yet efficient laboratory protocol. The present study was designed to examine if human embryos resulting from eggs frozen with an optimized vitrification protocol have similar developmental competence as those from fresh eggs.

Methods

Twenty recipients received donated eggs vitrified with a protocol in which short exposure time to the vitrification solution was used and 23 recipients received donated eggs and 6 patients had their own eggs vitrified with a modified protocol in which long exposure time to the vitrification solution was used. After warming, egg survival, fertilization, cleavage, blastocyst formation, clinical pregnancy and implantation rates were compared. The developmental competence of eggs vitrified with the optimized protocol was further compared with fresh eggs donated from the same donors.

Results

There was no difference in the oocyte survival, fertilization, cleavage, clinical pregnancy or implantation rates between the short and long protocol groups. However, blastocyst formation rate was significantly (P < 0.001) higher in the long protocol group (50.8%) than that in short protocol group (26.5%), resulting in more blastocysts being transferred and frozen. When frozen eggs vitrified with long protocol and fresh eggs from the same donors (12) were compared in 39 recipients, no differences were observed in terms of fertilization (86.4 vs 80.1%), blastocyst formation (50.0 vs 59.2%), clinical pregnancy (63.2 vs 60.0%) and implantation (41.7 vs 44.7%) rates. Four out of 6 patients had ongoing pregnancy after transfer of embryos from their own frozen eggs with a 46.2% implantation rate.

Conclusions

These results indicate that blastocyst development is an appropriate measure for egg survival after cryopreservation and frozen eggs have similar developmental potential as fresh eggs if they are frozen with an optimized method.

Fertility preservation for women with malignant diseases: ethical aspects and risks

As cancer treatment becomes more and more effective, there is greater life expectancy for cancer patients. Because of this, depending upon the modality used in the treatment of cancer, the matter of infertility emerges before us as an issue of increasing significance. Sperm cryopreservation and embryo cryopreservation are well-established methods of fertility preservation (FP). Besides these validated FP options, some FP techniques such as oocyte cryopreservation and ovarian tissue cryopreservation are as yet in the experimental stage. FP medicine has experienced some rapid developments in recent years. The advances in this branch of medicine, however, have also brought about new ethical, medical and legal issues. Some of these include problems with obtaining the informed consent of minors, issues that arise because of the experimental nature of some methods, financial problems and the accessibility of FP methods, and the question of what happens to gametes when a patient dies. This review seeks to discuss, in the light of current literature, some ethical and technical issues and risks related to the implementation of FP methods in women with cancer.

New trends in female fertility preservation: in vitro maturation of oocytes

As antineoplastic treatments have become more successful, an increasing number of women with cancer survive to endure the long-term consequences of chemotherapy. One of the most important of these consequences in young females is premature ovarian failure and infertility. Owing to increasing survival rates, many of these young women are seeking methods to preserve their fertility. Currently, embryo/oocyte cryopreservation obtained after controlled ovarian stimulation appears to provide the best fertility preservation option. However, patients may not have enough time to undergo ovarian stimulation prior to chemotherapy and/or have contraindications to exogenous gonadotropin administration owing to estrogen-dependant tumors. In vitro maturation of oocytes is an attractive alternative for fertility preservation in cancer patients because it does not require ovarian stimulation and it can be performed at any time of the menstrual cycle. In addition, this technique can be combined with ovarian tissue cryobanking. In this review, we discuss the position of in vitro maturation of oocytes in the fertility preservation strategy in young women.

Mature oocyte cryopreservation: a guideline

There is good evidence that fertilization and pregnancy rates are similar to IVF/ICSI with fresh oocytes when vitrified/warmed oocytes are used as part of IVF/ICSI for young women. Although data are limited, no increase in chromosomal abnormalities, birth defects, and developmental deficits has been reported in the offspring born from cryopreserved oocytes when compared to pregnancies from conventional IVF/ICSI and the general population. Evidence indicates that oocyte vitrification and warming should no longer be considered experimental. This document replaces the document last published in 2008 titled, "Ovarian Tissue and Oocyte Cryopreservation," Fertil Steril 2008;90:S241-6.

Allotransplantation of cryopreserved prepubertal mouse ovaries restored puberty and fertility without affecting methylation profile of Snrpn-DMR

OBJECTIVE

To evaluate the genetic safety of vitrification on the methylation imprints and the development and fertility potential of prepubertal mouse ovaries.

DESIGN

Experimental animal study.

SETTING

University-based fertility center.

ANIMAL(S)

Institute of Cancer Research (ICR) 10-day-old female mice, 10-week-old adult female mice, and 12-week-old adult male mice.

INTERVENTION(S)

Vitrification of juvenile mouse ovaries was performed using ED20 and EG5.5/30 solutions followed by retrieval of fresh and vitrified-warmed germinal vesicle (GV) oocytes for Snrpn differentially methylated regions (DMR) methylation analyses, collection of mature oocytes from superovulated ovarian grafts, in vitro fertility(IVF), and early embryonic development after heterotopic allotransplantation.

MAIN OUTCOME MEASURE(S)

Analysis of methylation status of Snrpn-DMR, percentage of fertilization, and blastocysts formation.

RESULT(S)

Methylation status of Snrpn-DMR from vitrified-warmed GV oocytes did not show significant alteration compared with that of controls, although a significant reduction of viable oocytes was observed. Puberty as well as endocrine function was restored, and no significant difference was shown in number of follicles, percentage of mice retaining fertility, and blastocyst formation among three groups.

CONCLUSION(S)

Our study proved that vitrification of prepubertal mouse ovaries did not alter the methylation profile of Snrpn-DMR and subsequent allotransplantation; IVF could restore the development and fertility potential.

ACE consensus meeting report: oocyte and embryo cryopreservation Sheffield 17.05.11

The UK Association of Clinical Embryologists (ACE) held a consensus workshop on Oocyte and Embryo Cryopreservation in Sheffield, UK, on May 17th, 2011. This was organized in response to a number of considerations including the increasing prevalence of vitrification for oocyte and embryo cryopreservation in the UK and worldwide, coupled with an apparent lack of consensus over which methods of cryopreservation are optimal. The workshop included expert opinion and survey data on current practice provided by participating clinics. The workshop highlighted that an increasing number of clinics in the UK are choosing vitrification rather than controlled rate freezing, particularly for the storage of oocytes and blastocysts. It was evident that a variety of solutions are used in conjunction with open and closed containers. Data supplied by the participating clinics suggest that both freezing and vitrification can lead to similar outcomes in early embryos and blastocysts and at the moment there is no evidence base to recommend either method over the other. The delegates arrived at a number of consensus points which reflected current practice in the UK, but recognized the need for well-designed trials with careful follow up of the children born before optimal methods can be agreed.

Relevance of assisted hatching in an oocyte donation programme using egg cryobanking: a prospective randomised study

OBJECTIVE

The objective of this prospective randomised study was to evaluate if there is an improvement in clinical outcomes when assisted hatching (AH) is performed in embryos derived from vitrified/warmed oocytes in an ovum donation programme using egg cryobanking.

STUDY DESIGN

Sixty oocyte recipients in a donation programme using egg cryobanking were randomly allocated to the assisted hatched (AH, n=30) or control group (n=30). The pregnancy and implantation rates were compared between the groups.

RESULTS

A total of 288 vitrified oocytes were warmed for the 60 recipients. Of the 288 vitrified oocytes, 94.8% survived. All surviving oocytes were sperm injected, and 83.5% underwent fertilisation. There were 172 good-quality embryos selected for transfer. The total pregnancy rate was 40%. The pregnancy rate did not differ between the AH and control groups (43.3% and 33.3%, respectively, p=0.1967), but AH resulted in a higher implantation rate (31.6% vs. 18.4%, p=0.0206).

CONCLUSION

Our study demonstrates the effectiveness of AH in embryos derived from warmed oocytes. Our results also suggest that oocyte cryopreservation can be considered as a tool for providing highly successful outcomes in an egg donor programme.

Recent advances in oocyte and ovarian tissue cryopreservation and transplantation

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

Fertility considerations in young women with hematological malignancies

The need for practice guidelines for fertility preservation in young women with hematological malignancies has been increased. To develop recommendations, publications relevant to fertility preservation and hematological cancers were identified through a PubMed database search and reviewed systematically, focusing on the effects of oncological treatments on fertility as well as on the efficacy, feasibility and risks of existing fertility preservation methods.

In-vitro maturation of human oocytes: before or after vitrification?

PURPOSE

This study aims to determine if in-vitro maturation (IVM) of human immature oocytes should be performed before or after vitrification.

METHODS

A total of 184 immature oocytes were randomly divided into two different groups: 100 were vitrified at metaphase II (MII) stage 24 h-48 h after IVM (group 1) and 84 were immediately vitrified at germinal vesicle (GV) or metaphase I (MI) stages and in vitro matured after warming (group 2).

RESULTS

Survival rate after warming was similar in both groups (86.9% versus 84.5%). However, oocyte maturation rate per collected oocyte was significantly higher for oocytes matured before vitrification (group 1, 46%) than for oocytes vitrified before IVM (group 2, 23.8%) (p < 0.01). Consequently, the number of MII oocytes inseminated per oocyte collected was significantly higher for group 1 (40%) than for group 2 (23.8%) (p < 0.05).

CONCLUSION

IVM procedure is more efficient when it is performed before oocyte vitrification.

Novel Approaches to the Cryopreservation of Human Spermatozoa: History and Development of the Spermatozoa Vitrification Technology

Cryobiology is very intensively applied in reproductive and veterinary medicine for preservation of gametes, embryos and reproductive tissues. Sub-zero temperatures combined with appropriate cryoprotective agents preserve the physiological and reproductive functions of the cells making long-term storage possible without loss of viability. With the use of cryoprotective agents it has become possible to develop cryopreservation techniques, such as the slow conventional freezing and vitrification that are in use in the present times. In slow controlled-rate conventional freezing extracellular ice crystals are formed whereas in vitrification no ice crystals are formed. Glass formation is compatible with the survival of the cell and the preservation of its intracellular structures provided the type(s) and concentrations of cryoprotectant used are not chemo- or osmotoxic. However, irrespective of the type of cooling method employed the cryosurvival of cells and tissues is influenced by the size and maturity of cells, amounts of intracellular water, quality and quantity of intracellular lipids, type of cells, their function and morphology. The intracellular milieu of cryopreserved cells and tissues remain less understood. The application of nanotechnology may help reveal and help advance our knowledge of the cryobiological principles involved in cryosurvival. At this moment the methods of cryopreservation that merit further investigation are vitrification and lyophilization. Vitrification is cheap if reagents are prepared in-house and the procedure can be performed rapidly. It has been successfully applied for gametes and embryos (of different stages of development), and reproductive cells/tissues, somatic cells and stem cells. However, vitrification is more demanding technically and requires operation and storage at sub-zero temperatures. On the other hand lyophilization deserves further investigation because it is a cheaper form of cryopreservation that may enable cryostorage at less demanding temperatures of 4°C and may even allow transport at ambient temperature. These possibilities are explored in this review.

Vitrification of in vitro matured oocytes collected from antral follicles at the time of ovarian tissue cryopreservation

BACKGROUND

In the past few years, cryopreservation of ovarian tissue has become an established procedure proposed in many centers around the world and transplantation has successfully resulted in full-term pregnancies and deliveries in human. This prospective study aims to evaluate the feasibility of vitrifying in vitro matured oocytes (IVM) isolated at the time of ovarian tissue cryopreservation to improve the efficiency of fertility preservation programs.

METHODS

Oocyte-cumulus complexes were retrieved from freshly collected ovarian cortex by aspirating antral follicular fluid, and were matured in vitro for 24-48 h prior to vitrification. Oocytes were matured in an IVM commercial medium (Copper Surgical, USA) supplemented with 75 mIU/ml FSH and 75 mIU/ml LH and vitrified using a commercial vitrification kit (Irvine Scientific, California) in high security vitrification straws (CryoBioSystem, France). Oocyte collection and IVM rates were evaluated according to the age, the cycle period and the amount of tissue collected.

RESULTS

Immature oocyte retrieval from ovarian tissue was carried out in 57 patients between 8 and 35 years of age, undergoing ovarian tissue cryopreservation. A total of 266 oocytes were isolated, 28 of them were degenerated, 200 were at germinal vesicle stage (GV), 35 were in metaphase I (MI) and 3 displayed a visible polar body (MII). The number of oocytes collected was positively correlated with the amount of tissue cryopreserved (p < 0.001) and negatively correlated with the age of the patients (p = 0.005). Oocytes were obtained regardless of menstrual cycle period or contraception. A total maturation rate of 31% was achieved, leading to the vitrification of at least one mature oocyte for half of the cohort.

CONCLUSIONS

The study showed that a significant number of immature oocytes can be collected from excised ovarian tissue whatever the menstrual cycle phases and the age of the patients, even for prepubertal girls.