Outcome of 518 salvage oocyte-cryopreservation cycles performed as a routine procedure in an in vitro fertilization program

Mitochondrial Dysfunction and Oxidative Stress Caused by Cryopreservation in Reproductive Cells

Mitochondria, fundamental organelles in cell metabolism, and ATP synthesis are responsible for generating reactive oxygen species (ROS), calcium homeostasis, and cell death. Mitochondria produce most ROS, and when levels exceed the antioxidant defenses, oxidative stress (OS) is generated. These changes may eventually impair the electron transport chain, resulting in decreased ATP synthesis, increased ROS production, altered mitochondrial membrane permeability, and disruption of calcium homeostasis. Mitochondria play a key role in the gamete competence to facilitate normal embryo development. However, iatrogenic factors in assisted reproductive technologies (ART) may affect their functional competence, leading to an abnormal reproductive outcome. Cryopreservation, a fundamental technology in ART, may compromise mitochondrial function leading to elevated intracellular OS that decreases sperm and oocytes' competence and the dynamics of fertilization and embryo development. This article aims to review the role played by mitochondria and ROS in sperm and oocyte function and the close, biunivocal relationships between mitochondrial damage and ROS generation during cryopreservation of gametes and gonadal tissues in different species. Based on current literature, we propose tentative hypothesis of mechanisms involved in cryopreservation-associated mitochondrial dysfunction in gametes, and discuss the role played by antioxidants and other agents to retain the competence of cryopreserved reproductive cells and tissues.

Sucrose ‘Versus’ Trehalose Cryoprotectant Modification in Oocyte Vitrification : A Study of Embryo Development

Numerous studies reported that vitrification, an ultra-rapid cooling technique, seems to be highly effective and could increase oocyte survival rate rather than slow freezing. The successful of oocyte vitrification depends on the proper combination of type and concentration of cryoprotectant. This study was addressed to determine the effects of the combination of type and concentration of cryoprotectants of vitrification media, notably in the embryo development. This experimental research was conducted by using oocyte obtained from thirty-two adult female Deutschland, Denken and Yoken (DDY) mice (7-8 weeks old). The MII mice oocytes were vitrified within 24 h after retrieval using the Cryotop method with cryoprotectants as follow : sucrose (16.5% EG, 16.5% DMSO, 0.5 mol/l sucrose), trehalose (16.5% EG, 16.5% DMSO, 0.5 mol/l trehalose) and Kitazato. The embryo development and morphological grading was observed at 2-cell and 8-cells under reverse phase light microscope and inverted microscope. This study demonstrated a good embryo development and morphological grading in sucrose and trehalose vitrification media. In embryo development, trehalose medium seems more superior compared to sucrose medium, even though Kitazato was the most superior compared to both. In the morphological grading, in 2-cells embryo, there were no significant differences between the three cryoprotectants, While, in 8-cells embryo, trehalose medium appeared to be superior compared to sucrose medium, even though seemed more inferior compared to Kitazato. The appropriate type and concentration of sugar as extracellular cryoprotectant was trehalose in oocyte vitrification based on embryo development, compared to sucrose.

Oocyte, embryo and blastocyst cryopreservation in ART: systematic review and meta-analysis comparing slow-freezing versus vitrification to produce evidence for the development of global guidance

BACKGROUND

Successful cryopreservation of oocytes and embryos is essential not only to maximize the safety and efficacy of ovarian stimulation cycles in an IVF treatment, but also to enable fertility preservation. Two cryopreservation methods are routinely used: slow-freezing or vitrification. Slow-freezing allows for freezing to occur at a sufficiently slow rate to permit adequate cellular dehydration while minimizing intracellular ice formation. Vitrification allows the solidification of the cell(s) and of the extracellular milieu into a glass-like state without the formation of ice.

OBJECTIVE AND RATIONALE

The objective of our study was to provide a systematic review and meta-analysis of clinical outcomes following slow-freezing/thawing versus vitrification/warming of oocytes and embryos and to inform the development of World Health Organization guidance on the most effective cryopreservation method.

SEARCH METHODS

A Medline search was performed from 1966 to 1 August 2016 using the following search terms: (Oocyte(s) [tiab] OR (Pronuclear[tiab] OR Embryo[tiab] OR Blastocyst[tiab]) AND (vitrification[tiab] OR freezing[tiab] OR freeze[tiab]) AND (pregnancy[tiab] OR birth[tiab] OR clinical[tiab]). Queries were limited to those involving humans. RCTs and cohort studies that were published in full-length were considered eligible. Each reference was reviewed for relevance and only primary evidence and relevant articles from the bibliographies of included articles were considered. References were included if they reported cryosurvival rate, clinical pregnancy rate (CPR), live-birth rate (LBR) or delivery rate for slow-frozen or vitrified human oocytes or embryos. A meta-analysis was performed using a random effects model to calculate relative risk ratios (RR) and 95% CI.

OUTCOMES

One RCT study comparing slow-freezing versus vitrification of oocytes was included. Vitrification was associated with increased ongoing CPR per cycle (RR = 2.81, 95% CI: 1.05-7.51; P = 0.039; 48 and 30 cycles, respectively, per transfer (RR = 1.81, 95% CI 0.71-4.67; P = 0.214; 47 and 19 transfers) and per warmed/thawed oocyte (RR = 1.14, 95% CI: 1.02-1.28; P = 0.018; 260 and 238 oocytes). One RCT comparing vitrification versus fresh oocytes was analysed. In vitrification and fresh cycles, respectively, no evidence for a difference in ongoing CPR per randomized woman (RR = 1.03, 95% CI: 0.87-1.21; P = 0.744, 300 women in each group), per cycle (RR = 1.01, 95% CI: 0.86-1.18; P = 0.934; 267 versus 259 cycles) and per oocyte utilized (RR = 1.02, 95% CI: 0.82-1.26; P = 0.873; 3286 versus 3185 oocytes) was reported. Findings were consistent with relevant cohort studies. Of the seven RCTs on embryo cryopreservation identified, three met the inclusion criteria (638 warming/thawing cycles at cleavage and blastocyst stage), none of which involved pronuclear-stage embryos. A higher CPR per cycle was noted with embryo vitrification compared with slow-freezing, though this was of borderline statistical significance (RR = 1.89, 95% CI: 1.00-3.59; P = 0.051; three RCTs; I2 = 71.9%). LBR per cycle was reported by one RCT performed with cleavage-stage embryos and was higher for vitrification (RR = 2.28; 95% CI: 1.17-4.44; P =  0.016; 216 cycles; one RCT). A secondary analysis was performed focusing on embryo cryosurvival rate. Pooled data from seven RCTs (3615 embryos) revealed a significant improvement in embryo cryosurvival following vitrification as compared with slow-freezing (RR = 1.59, 95% CI: 1.30-1.93; P < 0.001; I2 = 93%).

WIDER IMPLICATIONS

Data from available RCTs suggest that vitrification/warming is superior to slow-freezing/thawing with regard to clinical outcomes (low quality of the evidence) and cryosurvival rates (moderate quality of the evidence) for oocytes, cleavage-stage embryos and blastocysts. The results were confirmed by cohort studies. The improvements obtained with the introduction of vitrification have several important clinical implications in ART. Based on this evidence, in particular regarding cryosurvival rates, laboratories that continue to use slow-freezing should consider transitioning to the use of vitrification for cryopreservation.

Chemotherapy for gynaecological malignancies and fertility preservation

Infertility is an increasingly important issue for patients surviving cancer. Significant improvements in cancer management have led to greater numbers of patients living healthy and fulfilling lives for many years after a diagnosis of cancer, and the ability to bear children is a major component of well-being. Infertility is particularly challenging in gynaecological cancer, where multiple treatment modalities are often employed. Surgery may involve the removal of reproductive organs and subsequent chemotherapy may also lead to infertility. Mitigation of this through the use of cryopreservation of embryos, oocytes or ovarian tissue before chemotherapy may enable subsequent pregnancy in the patient or a surrogate mother. Suppression of ovarian function during chemotherapy is less well established, but promises a reduction in infertility without the risks associated with surgery. Similarly, evolving chemotherapy regimens with replacement of alkylating agents will reduce the incidence of infertility. With a combination of these techniques, an increasing proportion of patients may be able to conceive after completion of treatment, and there is no evidence of an increase in congenital abnormalities. This review discusses chemotherapy-induced infertility, interventions and success rates, and demonstrates that individualisation of management is required for optimum outcome.

The current challenges to efficient immature oocyte cryopreservation

Oocyte cryopreservation represents an important tool for assisted reproductive technology. It offers the opportunity to preserve fertility in women at risk of loss of the ovarian function for various pathologies. It also represents a treatment alternative for couples that cannot benefit from embryo cryopreservation because of moral, religious, or legal constrains. On the other hand, in vitro oocyte maturation has a range of applications. It can be applied in patients with a contraindication to ovarian stimulation to prevent ovarian hyperstimulation syndrome or to eliminate the risk of stimulation of hormone-sensitive tumours in cancer patients. However, while mature oocyte cryopreservation has found wide-spread application and oocyte in vitro maturation has a place for the treatment of specific clinical conditions, data on the efficiency of freezing of immature or in vitro matured oocytes are poorer. In this review we will focus on the combination of oocyte in vitro maturation with oocyte cryopreservation with particular emphasis on the biological implications of the cryopreservation of immature or in vitro matured oocytes. The two cryopreservation approaches, slow freezing and vitrification, will be discussed in relation to possible cryodamage occurring to subcellular structures of the oocyte and the functional interaction between oocyte and cumulus cells.

Genotoxicity assessment of mouse oocytes by comet assay before vitrification and after warming with three vitrification protocols

OBJECTIVE

To assess the genotoxicity of three oocyte vitrification protocols.

DESIGN

Murine assay.

SETTING

Biogenotoxicology research laboratory.

ANIMAL(S)

CD1 female mice.

INTERVENTION(S)

Three mouse oocyte groups were exposed to three commercialized human oocyte vitrification protocols. Protocols 1 and 2 contained dimethyl sulfoxide and ethylene glycol (EG), and protocol 3 contained EG and 1,2-propanediol (PrOH). DNA damage was first evaluated by comet assay after oocyte exposure to the three different equilibration and vitrification solutions. Comet assay was also performed after full vitrification and warming procedure and compared with a negative control group (oocytes stored in medium culture only) and a positive control group (oocytes exposed to hydrogen peroxide just before comet assay).

MAIN OUTCOME MEASURE(S)

DNA damage was quantified as Olive tail moment (OTM). Statistical analysis consisted of a Shapiro-Wilk test. Then, median protocol OTM was compared with the negative control group with the Mann-Whitney U test. The difference was considered to be statistically significant if the P value was <.05.

RESULT(S)

In both parts of our study, protocols 1 and 2 did not induce significant DNA damage, whereas protocol 3 induced statistically higher DNA damage compared with the negative control group.

CONCLUSION(S)

Vitrification protocols containing PrOH induced significant DNA damage on mouse oocytes, both before cooling and after warming. Therefore, for the moment, we prefer vitrification techniques without PrOH while we await more studies on PrOH toxicity and long-term evaluation.

Current trends and progress in clinical applications of oocyte cryopreservation

PURPOSE OF REVIEW

To delineate the current trends in the clinical application of oocyte cryopreservation.

RECENT FINDINGS

Although the first live birth from oocyte cryopreservation was reported approximately three decades ago, significant improvement in the clinical application of oocyte cryopreservation took place only over the past decade. On the basis of the available evidence suggesting that success rates with donor oocyte vitrification are similar to that of IVF with fresh donor oocytes, the American Society of Reproductive Medicine has recently stated that oocyte cryopreservation should no longer be considered experimental for medical indications, outlying elective oocyte cryopreservation. Meanwhile, a few surveys on the attitudes toward oocyte cryopreservation revealed that elective use for the postponement of fertility is currently the most common indication for oocyte cryopreservation. Most recently, a randomized controlled trial revealed important evidence on the safety of nondonor oocyte cryopreservation, and confirmed that the clinical success of vitrification is comparable to that of IVF with fresh oocytes.

SUMMARY

The evidence suggesting similar IVF success rates with both donor and nondonor cryopreserved oocytes compared with fresh oocytes will increase the utilization of elective oocyte cryopreservation. Appropriate counseling of women for oocyte cryopreservation requires the establishment of age-based clinical success rates with cryopreserved oocytes for various indications.

Age-specific probability of live birth with oocyte cryopreservation: an individual patient data meta-analysis

OBJECTIVE

To estimate age-specific probabilities of live birth with oocyte cryopreservation in nondonor (ND) egg cycles.

DESIGN

Individual patient data meta-analysis.

SETTING

Assisted reproduction centers.

PATIENT(S)

Infertile patients undergoing ND mature oocyte cryopreservation.

INTERVENTION(S)

PubMed was searched for clinical studies on oocyte cryopreservation from January 1996 through July 2011. Randomized and nonrandomized studies that used ND frozen-thawed mature oocytes with pregnancy outcomes were included. Authors of eligible studies were contacted to obtain individual patient data.

MAIN OUTCOME MEASURE(S)

Live birth probabilities based on age, cryopreservation method, and the number of oocytes thawed, injected, or embryos transferred.

RESULT(S)

Original data from 10 studies including 2,265 cycles from 1,805 patients were obtained. Live birth success rates declined with age regardless of the freezing technique. Despite this age-induced compromise, live births continued to occur as late as ages 42 and 44 years with slowly frozen and vitrified oocytes, respectively. Estimated probabilities of live birth for vitrified oocytes were higher than those for slowly frozen.

CONCLUSION(S)

The live birth probabilities we calculated would enable more accurate counseling and informed decisions for infertile women considering oocyte cryopreservation. Given the success probabilities, we suggest that policy makers should consider oocyte freezing as an integral part of prevention and treatment of infertility.

The 2004 Italian legislation on the application of assisted reproductive technology: epilogue

OBJECTIVE

To evaluate how the unique Italian fertility regulations (≤3 inseminated oocytes/cycle, transfer of all embryos, prohibition of embryo cryopreservation) affected outcomes of ART.

STUDY DESIGN

Case-control study from the Center of Reproductive Medicine, Arcispedale Santa Maria Nuova, Reggio Emilia, Italy. We compared outcomes of ART patients between five years before (n=1791) and five years after (n=2474) the implementation of the law.

RESULTS

The mean embryo transfer (ET) rate was 3.1±2.1 and 1.7±1.1 before and after the law. Significantly more ICSI procedures were performed in women above 35 years old during the post-law period. The ET rate was higher before (88.6%) than after (80.5%) the law (OR 1.9, 95% CI 1.6, 2.2) especially in women >37 years undergoing ICSI (88.2 vs. 76.1%; OR 2.3, 95% CI 1.3, 4.2). The clinical pregnancy rates were practically unchanged but the proportion of triplet births significantly decreased after the law (10.3 vs. 4.1%, OR 2.7, 95% CI 1.4, 5.0).

CONCLUSION

In contrast to interim analyses, we found that the statutory obligation to transfer all available embryos produced from up to three inseminated oocytes reduced the ET rates, especially in older women, and decreased the triplet births rate.

Implantation rates of embryos generated from slow cooled human oocytes from young women are comparable to those of fresh and frozen embryos from the same age group

Previous reports of slow cooling of human mature oocytes have shown a reduced clinical efficiency relative to fresh oocytes. This study reports that equivalent fertilization and implantation rates to those obtained using fresh oocytes and cryopreserved embryos can be achieved with human mature oocytes dehydrated in 1.5 M propanediol and 0.2 M sucrose at 37°C and cryopreserved using slow cooling rates.

Detection of follicular fluid and serum antibodies by protein microarrays in women undergoing in vitro fertilization treatment

A protein microarray serological assay was used to assess the antibody profile of 102 women subjected to in vitro fertilization treatment. The studies were conducted on pairs of serum and follicular fluid samples, collected from each woman on the same day at the time of oocyte recovery. The samples, stored as frozen aliquotes, were assessed by both microarray and ELISA. Follicular fluids and sera were screened to detect the presence of specific IgG and IgM antibodies against seven vertically transmitted pathogens. The IgG reactivity of follicular fluids closely mirrored that of serum in all the patients and for all the antigens, with an agreement of more than 85%. IgM antibodies were undetectable in follicular fluids. The antibody patterns were subsequently related to the biological and clinical outcomes of in vitro fertilization cycles. The results showed that varicella zoster virus (VZV) IgG positive women and cytomegalovirus (CMV) IgG negative women had on average a higher number of inseminated, good quality oocytes compared to VZV IgG negative and CMV IgG positive women. In addition, the rate of successful embryo transfers was significantly higher in Toxoplasma gondii IgG negative women than in their positive counterparts. Overall, the microarray was proven to be a suitable tool for detecting analytes in follicular fluids, therefore supporting its application in a wide spectrum of investigations.

Fertility preservation for cancer patients: a review

Infertility can arise as a consequence of treatment of oncological conditions. The parallel and continued improvement in both the management of oncology and fertility cases in recent times has brought to the fore-front the potential for fertility preservation in patients being treated for cancer. Oncologists must be aware of situations where their treatment will affect fertility in patients who are being treated for cancer and they must also be aware of the pathways available for procedures such as cryopreservation of gametes and/or embryos. Improved cancer care associated with increased cure rates and long term survival, coupled with advances in fertility treatment means that it is now imperative that fertility preservation is considered as part of the care offered to these patients. This can only be approached within a multidisciplinary setting. There are obvious challenges that still remain to be resolved, especially in the area of fertility preservation in prepubertal patients. These include ethical issues, such as valid consent and research in the area of tissue retrieval, cryopreservation, and transplantation.

Prospective randomized comparison of human oocyte cryopreservation with slow-rate freezing or vitrification

OBJECTIVE

To compare cryopreservation of mature human oocytes with slow-rate freezing and vitrification and determine which is most efficient at establishing a pregnancy.

DESIGN

Prospective randomized.

SETTING

Academically affiliated, private fertility center.

PATIENT(S)

Consenting patients with concerns about embryo cryopreservation and more than nine mature oocytes at retrieval were randomized to slow-rate freezing or vitrification of supernumerary (more than nine) oocytes.

INTERVENTION(S)

Oocytes were frozen or vitrified, and upon request oocytes were thawed or warmed, respectively.

MAIN OUTCOME MEASURE(S)

Oocyte survival, fertilization, embryo development, and clinical pregnancy.

RESULT(S)

Patient use has resulted in 30 thaws and 48 warmings. Women's age at time of cryopreservation was similar. Oocyte survival was significantly higher following vitrification/warming (81%) compared with freezing/thawing (67%). Fertilization was more successful in oocytes vitrified/warmed compared with frozen/thawed. Fertilized oocytes from vitrification/warming had significantly better cleavage rates (84%) compared with freezing/thawing (71%) and resulted in embryos with significantly better morphology. Although similar numbers of embryos were transferred, embryos resulting from vitrified oocytes had significantly enhanced clinical (38%) pregnancy rates compared with embryos resulting from frozen oocyte (13%). Miscarriage and/or spontaneous abortion rates were similar.

CONCLUSION(S)

Our results suggest that vitrification/warming is currently the most efficient means of oocyte cryopreservation in relation to subsequent success in establishing pregnancy.

Multicenter observational study on slow-cooling oocyte cryopreservation: clinical outcome

OBJECTIVE

To evaluate the efficacy of oocyte cryopreservation by a single slow-cooling protocol involving sucrose (0.2 mol/L) in the freezing solution.

DESIGN

Observational comparison of the clinical outcome in fresh and frozen thawed cycles.

SETTING

Public and private IVF centers.

PATIENT(S)

Infertile couples undergoing IVF treatment.

INTERVENTION(S)

Use of a maximum three oocytes in fresh cycles, as established by local law, and cryopreservation and later use of surplus oocytes. Likewise fresh cycles, maximum three thawed oocytes were used per cycle. All thawed oocytes were microinjected.

MAIN OUTCOME MEASURE(S)

Embryologic and clinical parameters of fresh and thawed cycles.

RESULT(S)

Two thousand forty-six patients underwent 2,209 oocyte retrievals involving oocyte cryopreservation. Overall, the survival rate of thawed oocytes was 55.8%. In 940 thaw cycles, the mean numbers of inseminated oocytes and fertilization rates were significantly decreased vs. fresh cycles outcomes (2.6 ± 0.7 vs. 2.9 ± 0.2 and 72.5% vs. 78.3%, respectively), as were the rates of implantation (10.1% vs. 15.4%), pregnancy rates per transfer (17.0% vs. 27.9%), and pregnancy rates per cycle (13.7% vs. 26.2%). Differences in clinical outcome were found among centers. A pregnancy rate per thawing cycle above 14% was achieved by most clinics. Fifty-seven retrievals involving oocyte cryopreservation achieved a pregnancy after fresh embryo replacement. Implantation and pregnancy rates per embryo transfer and per thawing cycles were 17.5%, 28.6%, and 24.6%, respectively.

CONCLUSION(S)

Under the conditions tested, the clinical outcome of oocyte slow-cooling cryopreservation is reduced compared with fresh cycles. Nevertheless, in cases of inapplicability of embryo cryopreservation, oocyte cryopreservation should be offered to patients with surplus oocytes.

A PolScope evaluation of meiotic spindle dynamics in frozen-thawed oocytes

In mature human oocytes, the metaphase II (MII) spindle presence and birefringence signal detected through the PolScope may vary before and after freezing. In particular, spindle dynamics during the first few hours after thawing is still under study. In this study, oocytes from stimulated ovaries were cryopreserved in 1.5 mol/l 1,2-propanediol with 0.3 mol/l sucrose using a slow freezing-rapid thawing method. Oocytes were examined with the PolScope for the presence, intensity of signal birefringence and size of the meiotic spindle before freezing and at 0, 1 and 2 h post-thaw (where 0 h = the time of the end of the thawing procedure). Of the 173 surviving oocytes exhibiting a spindle before freezing, 82.7% (143/173) showed spindle birefringence within 1 h of thawing. However, at the end of the thawing procedure the intensity of spindle birefringence (retardance) and the spindle length were smaller in comparison to the pre-freezing condition. These parameters increased after 1 h, although were not restored to the value observed before freezing. No significant changes were observed by extending the culture to 2 h.

Human oocyte cryopreservation: comparison between slow and ultrarapid methods

The success of reproductive technologies is facilitated by the cryopreservation of embryos and gametes. In Italy, where legislation prohibits zygote and embryo cryopreservation, clinics have extensively introduced oocyte cryopreservation. Two different strategies of oocyte cryopreservation are available: slow freezing or ultrarapid cooling (vitrification). Although the results are very encouraging with both methods, there is still controversy regarding both the procedure itself and the most suitable method to use. This study reports the routine application of the two different oocyte cryopreservation methods in programmes running in two consecutive periods. The study centre carried out 286 thawing cycles for a total of 1348 thawed oocytes cryopreserved by the slow-freezing method and 59 warming cycles for a total of 285 warmed oocytes cryopreserved by vitrification. Comparison of the outcomes obtained with the slow-freezing method versus vitrification in women who underwent IVF for infertility showed survival, fertilization, pregnancy and implantation rates of 57.9% versus 78.9% (P < 0.0001), 64.6% versus 72.8% (P = 0.027), 7.6% versus 18.2% (P = 0.021) and 4.3% versus 9.3% (P = 0.043) respectively. These results suggest that oocyte vitrification is associated with a better outcome than the slow-freezing method.

Embryo development of fresh 'versus' vitrified metaphase II oocytes after ICSI: a prospective randomized sibling-oocyte study

BACKGROUND

A successful oocyte cryopreservation programme is of utmost importance where a limited number of oocytes can be inseminated per cycle, to overcome legal and ethical issues related to embryo storage, for oocyte donation programmes and for fertility preservation (especially for cancer patients). Vitrification has been recently proposed as an effective procedure for this purpose.

METHODS

In order to validate the effectiveness of oocyte vitrification a non-inferiority trial was started on sibling metaphase II (MII) oocytes. To demonstrate the non-inferiority based on an absolute difference of 17% in the fertilization rate per sibling oocyte, a minimum of 222 oocytes were required. After oocyte denudation, MII oocytes with normal morphology were randomly allocated to fresh ICSI insemination or to vitrification procedure. If pregnancy was not obtained a subsequent ICSI cycle was performed with warmed oocytes of the same cohort. In both groups, three oocytes were inseminated per cycle by ICSI procedure. Primary end-points were fertilization rates calculated per warmed and per injected oocytes. Secondary end-points were zygote and embryo morphology.

RESULTS

A total of 244 oocytes were involved in this study. Of the 120 fresh sibling oocytes inseminated, 100 were fertilized (83.3%). Survival rate of sibling vitrified oocytes was 96.8% (120/124 oocytes). Fertilization rate after ICSI was 76.6% (95/124) per warmed oocyte and 79.2% (95/120) per survived/inseminated oocyte. No statistical difference in fertilization rates was observed between the two groups when calculated per sibling oocytes (absolute difference -6.73%; OR: 0.65; 95% CI = 0.33-1.29; P = 0.20) and per inseminated oocyte (absolute difference -4.17%; OR: 0.76; 95% CI = 0.37-1.53; P = 0.50). Embryo development was also similar in both treatment groups up till Day 2. The percentage of excellent quality embryos was 52.0% (52/100) in the fresh group and 51.6% (49/95) in the vitrification group (absolute difference -0.43%; OR: 0.98; 95% CI = 0.53-1.79; P = 0.9). The mean age of the 40 patients included in this study was 35.5 +/- 4.8 years (range 26-42). Fifteen clinical pregnancies were obtained in the vitrification cycles of 39 embryo transfers performed (37.5% per cycle, 38.5% per embryo transfer), with an implantation rate of 20.2% (19/94). Three spontaneous miscarriages occurred (20%). Twelve pregnancies are ongoing (30.0% per cycle, 30.8% per embryo transfer) beyond 12 weeks of gestation.

CONCLUSIONS

Our results indicate that oocyte vitrification procedure followed by ICSI is not inferior to fresh insemination procedure, with regard to fertilization and embryo developmental rates. Moreover, ongoing clinical pregnancy is compatible with this procedure, even with a restricted number of oocytes available for insemination. The promising clinical results obtained, in a population of infertile patients, need to be confirmed on a larger scale.

CLINICAL TRIALS REGISTRATION NUMBER

iSRCTN60158641.

The effect of the 2004 Italian law on outcomes of assisted reproduction technology in severe male factor infertility

The Italian law regulating assisted reproductive technologies that came into force in 2004 restricts the number of fertilized oocytes per cycle to three, obliges the subsequent transfer of all resulting embryos and prohibits the freezing of surplus embryos. This study evaluates the impact of the law on severe oligozoospermic, cryptozoospermic, obstructive azoospermic and non-obstructive azoospermic patients. Intracytoplasmic sperm injection outcomes of 1066 cycles performed in the 4years before the passing of the law were compared with 804 cycles performed in the 4years after the law came to pass. Globally, analysis of clinical and obstetric outcomes showed a significant decrease in terms of pregnancy and delivery rates per cycle (17.8% versus 10.9% and 14.2% versus 8.5%, respectively) and per embryo transfer (18.8% versus 13.8% and 15.0% versus 10.7%, respectively), and a significant drop in multiple deliveries (35.1% versus 17.6%) in the post-law period. Cryptozoospermic and azoospermic couples were affected by the Italian law more than severe oligozoospermic couples. The results showed that the Italian law limits the efficiency of assisted reproduction treatment in couples with severe male factor. It is hoped that the Italian assisted reproductive technologies law is altered as soon as possible, allowing the insemination of more than three oocytes.

Over 900 oocyte cryopreservation babies born with no apparent increase in congenital anomalies

Over the past decade, the number of reported live births resulting from oocyte cryopreservation has rapidly increased. To appreciate the true number of children born, verified live births were tabulated and assessed. A literature search was performed; authors were then contacted to verify birth outcomes and provide updates. A database including all verified live born infants was constructed. A total of 58 reports (1986-2008) were reviewed, which included 609 live born babies (308 from slow freezing, 289 from vitrification and 12 from both methods). Additionally, 327 other live births were verified. Of the total 936 live borns, 1.3% (12) were noted to have birth anomalies: three ventricular septal defects, one choanal and one biliary atresia, one Rubinstein-Taybi syndrome, one Arnold-Chiari syndrome, one cleft palate, three clubfoot and one skin haemangioma. Compared with congenital anomalies occurring in naturally conceived infants, no difference was noted. With more live born data accumulating, this procedure may become mainstream as a fertility preservation option, particularly for women diagnosed with malignancy requiring cytotoxic therapy. A registry would help to assure the safest, most expeditious development of this technology.

Impact of insemination technique, semen quality and oocyte cryopreservation on pronuclear morphology of zygotes derived from sibling oocytes

Pronuclear morphology seems to be an important predictive value of zygote development and integrity. In this study we want to evaluate the effect of insemination technique, male factor and oocyte cryopreservation on pronuclear morphology of zygotes derived from sibling oocytes in our Centre of Reproductive Medicine, Department of Obstetrics and Gynecology, Arcispedale S. Maria Nuova, Reggio Emilia, Italy. Subjects (n = 190) were submitted to IVF cycles with non-frozen and frozen sibling oocytes. Morphological evaluations were assessed using zygote pronuclear morphology (pronuclei, nucleoli and axis) in four groups: Group 1: 144 zygotes from 85 conventional IVF cycles with non-frozen oocytes; Group 2: 164 zygotes from 85 intracytoplasmic sperm injection (ICSI) cycles with Group 1 patients' sibling frozen oocytes; Group 3: 221 zygotes from 123 ICSI cycles with non-frozen oocytes; Group 4: 197 zygotes from 123 ICSI cycles with Group 3 patients' sibling frozen oocytes. No differences between Group 1 and Group 2 were seen. Group 3 was statistically different from Group 4 in relation to the nucleolar morphology. Oocyte cryopreservation procedure modified the nucleolar morphology of zygotes only in the presence of poor semen quality.

Efficiency of human oocyte slow freezing: results from five assisted reproduction centres

It has been demonstrated previously that freezing oocytes within 2 h of retrieval increases the efficiency of cryopreservation via a slow-freezing/rapid-thawing protocol with 0.3 mol/l sucrose (SF/RT 0.3). The aim of this multicentre survey was to verify this observation on a larger scale. This was a retrospective study on the clinical outcome of 510 SF/RT 0.3 cycles divided into two groups: group A, freezing oocytes within 2 h of retrieval; group B, freezing oocytes more than 2 h after retrieval. The rate of best-quality embryos was significantly higher (33.24%) in group A than in group B (16.20%, P < 0.001). Pregnancy and implantation rates were 30.07% and 15.08% in group A versus 8.97% and 4.57% in group B (P < 0.001). Clinical pregnancy rates per thawed and per injected oocyte in group A were 5.53% and 10.41%, versus 1.46% and 2.77% in group B (P < 0.001). The overall yield from oocytes cryopreserved within 2 h of retrieval (group A) was 6.49 implantations per 100 oocytes thawed versus 1.74 for group B (P < 0.001). Embryo quality, pregnancy and implantation rates, and clinical efficiency of thawing cycles were all significantly improved when cryopreservation was carried out within 2 h of oocyte retrieval.

The effect of the 2004 Italian legislation on perinatal outcomes following assisted reproduction technology

OBJECTIVE

To assess the perinatal outcomes of the first three years under the 2004 Italian reproductive legislation obligating transfer of all embryos resulting from insemination of < or =3 oocytes.

STUDY DESIGN

We compared the perinatal results of clinical assisted reproductive technology (ART) pregnancies during the three years following the new Italian legislation with the previous three years.

RESULTS

There were 583 and 571 clinical pregnancies during the respective periods. Before the law, the overall embryonic and fetal loss rates were significantly higher resulting in a significantly lower rate of live born infants and significantly fewer clinical pregnancies with at least one live born infant. Quadruplet and quintuplet pregnancies were entirely eliminated following the 2004 law but the neonatal mortality rate was not different between the two study periods.

CONCLUSION

The 2004 Italian infertility legislation led to improved quantitative and qualitative outcomes of ART.

Nuclear transfer and oocyte cryopreservation

Somatic cells can be reprogrammed to a totipotent state through nuclear transfer or cloning, because it has been demonstrated that the oocyte has the ability to reprogramme an adult nucleus into an embryonic state that can initiate the development of a new organism. Therapeutic cloning, whereby nuclear transfer is used to derive patient-specific embryonic stem cells, embraces an entire new opportunity for regenerative medicine. However, a key obstacle for human therapeutic cloning is that the source of fresh human oocytes is extremely limited. In the present review, we propose prospective sources of human oocytes by using oocyte cryopreservation, such as an oocyte bank and immature oocytes. We also address some potential issues associated with nuclear transfer when using cryopreserved oocytes. In the future, if the efficacy and efficiency of cryopreserved oocytes are comparable to those of fresh oocytes in human therapeutic cloning, the use of cryopreserved oocytes would be invaluable and generate a great impact to regenerative medicine.

Human oocyte cryopreservation in infertility and oncology

PURPOSE OF REVIEW

To evaluate the present state of research and clinical application of human oocyte cryopreservation in infertility and oncology.

RECENT FINDINGS

Recent literature documents have an increasing interest in cryopreserving human eggs. A number of studies report on different freezing protocols and various types of clinical application. Increasing attention is paid to vitrification as an alternative to slow cooling for oocyte cryopreservation. Several studies cover the modification of meiotic spindle during cryopreservation in order to assess the less damaging cryopreservation system. The first births with cryopreserved oocytes in cancer patients are reported.

SUMMARY

Egg freezing may circumvent the ethical and legal concerns regarding embryo cryopreservation, increase assisted reproduction flexibility and be a concrete option to save fertility in women with cancer. Recently, egg survival and pregnancy rates improved, with the birth of more than 500 children. The birth rate per thawed oocyte is around 5-6%. As regards safety, data on birth defects seems to be reassuring so far but must be monitored by an international registry. Comparative studies between slow freezing and vitrification in the same patient population are needed to elucidate pros and cons of each technique.

Nitric oxide as an early marker of human embryo metabolic cleavage in ART using fresh or thawed oocytes

OBJECTIVE

To study a possible role of nitric oxide (NO) as a marker of development in the early phases of human embryo cleavage during assisted reproduction.

STUDY DESIGN

179 women having ART were included. 123 women used fresh oocytes and 56 oocyte thawing cycles in the Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Arcispedale S. Maria Nuova, between July 2005 and June 2006; 57 patients had IVF and 122 patients had ICSI. NO concentrations in IVF or ICSI embryo culture media were assessed by monitoring levels of NO stable oxidation products (nitrites/nitrates). Analysis of embryo quality was performed. Student's t-test or Mann-Whitney and logistic regression model tests were applied to the data.

RESULTS

In patients using fresh oocytes, there were greater NO production in embryos derived from ICSI than from IVF after 52 h of culture (38.64 micromol/L vs 11.2 micromol/L, p<0.05). No correlation with embryo quality was observed. Embryos derived from fresh oocytes produce more NO than embryos from thawed oocytes both after 48 and 52 h of culture (16.12 micromol/L vs 6.83 micromol/L and 25.93 micromol/L vs 2.98 micromol/L respectively, p<0.05).

CONCLUSION(S)

NO in embryo culture media is not a metabolic cleavage marker or a marker of embryo quality in ART. However, it could be an important parameter in the investigation of metabolism in frozen/thawed oocytes.

Human oocyte and ovarian tissue cryopreservation and its application

PURPOSE

To review the recent progress in human oocyte and ovarian tissue cryopreservation, and in the application of these two technologies for preserving female fertility of patients who are undergoing cancer treatment.

DESIGN

The literature on human oocyte and ovarian tissue freezing was searched with PubMed. The scientific background, current developments and potential future applications of these two methods were reviewed.

RESULTS

Chemotherapy and/or radiotherapy can induce premature ovarian failure in most of female cancer patients. Consequently, there has been a greater need for options to preserve the reproductive potential of these individuals. However, options are somewhat limited currently, particularly following aggressive chemotherapy and/or radiotherapy treatment protocols. In recent years, there have been considerable advances in the cryopreservation of human oocytes and ovarian tissue. For women facing upcoming cancer therapies, cryopreservation of ovarian tissue and oocytes is a technology that holds promise for banking reproductive potential for the future. Recent laboratory modifications have resulted in improved oocyte survival, oocyte fertilization, and pregnancy rates from frozen-thawed oocytes in IVF. This suggests potential for clinical application.

CONCLUSIONS

In the case of patients who are facing infertility due to cancer therapy, oocyte cryopreservation may be one of the few options available. Ovarian tissue cryopreservation can only be recommended as an experimental protocol in carefully selected patients. In ovarian tissue transplantation, more research is needed in order to enhance the revascularization process with the goal of reducing the follicular loss that takes place after tissue grafting. These technologies are still investigational, although tremendous progress has been made. The availability of such treatment will potentially lead to its demand not only from patients with cancer but also from healthy women who chose to postpone childbearing until later in life and therefore wish to retain their fertility.

Human oocyte vitrification: the permeability of metaphase II oocytes to water and ethylene glycol and the appliance toward vitrification

OBJECTIVE

To determine the permeability of human metaphase II oocytes to ethylene glycol and water in the presence of ethylene glycol, and to use this information to develop a method to vitrify human oocytes.

DESIGN

An incomplete randomized block design.

SETTING

A university-affiliated assisted reproductive center.

PATIENT(S)

Women undergoing assisted reproduction in the Center for Reproductive Medicine at Shandong University.

INTERVENTION(S)

Oocytes were exposed to 1.0 molar ethylene glycol in a single step and photographed during subsequent volume excursions.

MAIN OUTCOME MEASURE(S)

A two-parameter model was employed to estimate the permeability to water and ethylene glycol.

RESULT(S)

Water permeability ranged from 0.15 to 1.17 microm/(min.atm), and ethylene glycol permeability ranged from 1.5 to 30 microm/min between 7 degrees C at 36 degrees C. The activation energies for water and ethylene glycol permeability were 14.42 Kcal/mol and 21.20 Kcal/mol, respectively.

CONCLUSION(S)

Despite the lower permeability of human metaphase II oocytes to ethylene glycol compared with previously published values for propylene glycol and dimethylsulfoxide, methods to add and remove human oocytes with a vitrifiable concentration of ethylene glycol can be designed that prevent excessive osmotic stress and minimize exposure to high concentrations of this compound.

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

OBJECTIVE

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

DESIGN

Animal study.

SETTING

Lyon Veterinary School, France.

ANIMAL(S)

Ewes.

INTERVENTION(S)

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

MAIN OUTCOME MEASURE(S)

Median ischemia time, progesterone levels, histologic examination.

RESULT(S)

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

CONCLUSION(S)

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

The effect of selecting oocytes for insemination and transferring all resultant embryos without selection on outcomes of assisted reproduction

OBJECTIVE

To evaluate the effect of selecting three best oocytes for insemination and transfer of all resultant embryos on outcomes of assisted reproductive technologies (ART).

STUDY DESIGN

Comparative study.

SETTING

The Center of Reproductive Medicine, Arcispedale Santa Maria Nuova, Reggio Emilia, Italy.

PATIENT(S)

Women undergoing ART during the period March 10, 2004 to March 9, 2006.

INTERVENTION(S)

Comparing outcomes of ART following transfers of 3 "excellent" (n = 267) embryos and cycles in which none of the embryos was considered "excellent quality" (n = 176).

MAIN OUTCOME MEASURE(S)

Rates of fertilization, pregnancy, "take-home baby," and multiple pregnancies.

RESULTS

The average number of retrieved oocytes and the average number of inseminated oocytes of good quality were similar in both groups. Intracytoplasmic sperm injection was performed four to five times more often in cycles without "excellent quality" irrespective of the patient's age (odds ratio 4.6, 95% confidence interval 3.0, 7.1). The two groups had similar rates of implantation, total pregnancies/ET, clinical intrauterine pregnancy, singleton and multiple births, and "take-home" baby rate. This similarity persisted irrespective of the patient's age.

CONCLUSION(S)

The selection of oocytes for insemination and transfer of all available embryos irrespective of their quality did not change outcomes of ART.

Human oocyte cryopreservation

The clinical role of oocyte cryopreservation in assisted reproduction, as an adjunct to sperm and embryo cryopreservation, has been comparatively slow to evolve as a consequence of theoretical concerns related to efficacy and safety. Basic biological studies in the 1990's alleviated many of these concerns leading to more widespread adoption of the technology. While a number of babies were born from the approach validated in the 1990's, its perceived clinical inefficiency led to the search for improved methods. Introduction of elevated dehydrating sucrose concentrations during cryopreservation increased survival and fertilization rates, but there is no well-controlled evidence of improved clinical outcome. Similarly, the use of sodium-depleted cryopreservation media has not been demonstrated to increase clinical efficiency. More recently, and in the absence of basic biological studies addressing safety issues, the application of vitrification techniques to human oocytes has resulted in reports of a number of live births. The small number of babies born from clinical oocyte cryopreservation and the paucity of well-controlled studies currently preclude valid comparisons between approaches. Legal restrictions on the ability to select embryos from cryopreserved oocytes in Italy, where many of the available reports originate, also obscure attempts to assess oocyte cryopreservation objectively.

The effect of legislation on outcomes of assisted reproduction technology: lessons from the 2004 Italian law

OBJECTIVE

To evaluate the effect of the 2004 Italian regulations (insemination of <or=3 oocytes/cycle, transfer of all embryos, prohibition of embryo cryopreservation) on outcomes of assisted reproduction treatment (ART).

DESIGN

Case-control study.

SETTING

The Center of Reproductive Medicine, Arcispedale Santa Maria Nuova, Reggio Emilia, Italy.

PATIENT(S)

Women undergoing ART for the first time.

INTERVENTION(S)

Comparing outcomes of ART between 2 years before (n = 900) and after (n = 936) the law's implementation (March 10, 2004).

MAIN OUTCOME MEASURE(S)

Rates of fertilization, pregnancy, "take-home baby," and multiple pregnancies.

RESULT(S)

During the pre-law period, statistically significantly more patients reached embryo transfer (odds ratio 1.9; 95% CI, 1.5, 2.5), and embryo transfer rate per cycle was statistically significantly higher (3.1 +/- 1.7 vs. 2.2 +/- 0.7), but the overall transfer of good embryos was lower (OR 0.6; 95% CI, 0.5, 0.8). The pregnancy rates per aspiration cycle were similar between the periods, but the pregnancy rate per embryo transfer and birth rate with at least one liveborn baby per embryo transfer were statistically significantly lower in the pre-law period (OR 0.7; 95% CI, 0.5, 0.9). The multiple births rate was not different between the two periods.

CONCLUSION(S)

In contrast to prior pessimistic expectations, the obligation to transfer all available embryos produced from <or=3 inseminated oocytes neither reduced success rates of ART nor increased the multiple births rate.

[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.