Maturation outcomes are improved following Cryoleaf vitrification of immature human oocytes when compared to choline-based slow-freezing

C-phycocyanin improves the developmental potential of cryopreserved human oocytes by minimizing ROS production and cell apoptosis

PURPOSE

The cryopreservation process damages oocytes and impairs development potential. As a potent antioxidant, C-phycocyanin (PC) regulates reproductive performance. However, its beneficial effects on vitrified human oocytes remain unknown.

METHODS

In this study, human GV-stage oocytes obtained from controlled ovarian hyperstimulation (COH) cycles were randomly allocated to three groups: fresh oocyte without freezing (F group), vitrification in medium supplemented with PC (P group), and vitrification in medium without PC as control group (C group). After warming, viable oocytes underwent in vitro maturation.

RESULTS

Our results showed that 3 μg/mL PC treatment increased the oocyte maturation rate after cryopreservation. We also found that PC treatment maintains the regular morphological features of oocytes. After PC treatment, confocal fluorescence staining showed a significant increase in the mitochondrial membrane potential of the vitrified oocytes, along with a notable decrease in intracellular reactive oxygen species and the early apoptosis rate. Finally, after in vitro maturation and parthenogenetic activation, vitrified oocytes had a higher potential for cleavage and blastocyst formation after PC treatment.

CONCLUSION

Our results suggest that PC improves the developmental potential of cryopreserved human GV-stage oocytes by attenuating oxidative stress and early apoptosis and increasing the mitochondrial membrane potential.

Cryopreservation of Mammalian Oocytes: Slow Cooling and Vitrification as Successful Methods for Cryogenic Storage

Two basic methods for the laboratory-focused cryopreservation of mammalian oocytes are described, based on work with murine oocytes. One method uses a relatively low concentration of the cryoprotectant propanediol plus sucrose and requires controlled rate cooling equipment to achieve a slow cooling rate. This method has also produced live births from cryopreserved human oocytes. The second method, which is described here, employs a high concentration of the cryoprotectant dimethyl sulfoxide plus a low concentration of polyethylene glycol. This is a vitrification method, which involves ultra-rapid cooling by plunging standard straws into liquid nitrogen vapor, hence avoiding the need for specialized equipment, but requires technical ability to manipulate the oocytes quickly in the highly concentrated cryoprotectant solutions. Murine oocytes that have been vitrified using this technique have resulted in live births. Vitrification using other cryoprotectant mixtures is now a popular clinically accepted method for cryobanking of human oocytes.

Fertility preservation for trans men: frozen-thawed in vitro matured oocytes collected at the time of ovarian tissue processing exhibit normal meiotic spindles

PURPOSES

At the moment of sex reassignment surgery (SRS), the ovarian tissue is sometimes cryopreserved as fertility preservation option for female-to-male trans men, also called trans men. During this preparation, cumulus-oocyte-complexes (COCs) can be found and in vitro matured. It is not known if these oocytes are developmentally competent. In order to use these oocytes for fertility preservation and subsequent fertilization, a normal spindle structure before and after vitrification is necessary.

METHODS

A total of 680 COCs were collected from trans men (n = 16) at the time of SRS and after testosterone treatment. The COCs were subjected to in vitro maturation and those that reached the metaphase II stage (MII) were collected and split into two groups; group 1 was immediately fixed for spindle staining and group 2 was first vitrified and warmed followed by spindle staining. Statistical analysis was performed by Fisher's exact test.

RESULTS

After 48 h in vitro maturation, 38.1% of COCs were at MII stage. Those oocytes were split in two groups: (1) 126 MII oocytes in the noncryopreservation group and (2) 133 MII oocytes underwent cryopreservation through vitrification. The oocyte survival rate, after 2 h warming, was 67.7%. Both the noncryopreserved and the vitrified group showed comparable results concerning normal spindle structure and chromosomes alignment, 85.7% vs. 92.2% (P = 0.27).

CONCLUSIONS

Spindle structure analysis and chromosomal alignment after vitrification seem normal in in vitro matured COCs collected during the tissue processing of ovaries in trans men at the time of SRS. The MII oocytes do not seem to be morphologically affected by prolonged testosterone treatment.

In vitro maturation of human immature oocytes for fertility preservation and research material

Aim

In recent years, the importance of fertility preservation (FP) has increased. In vitro maturation (IVM), an important technique in FP, has started to be used in the clinic, but controversies persist regarding this technique. Here, a survey of IVM for FP is provided.

Methods

Based on a literature review, the applications of FP, methods of FP, IVM of oocytes that had been collected in vivo and ex vivo, maturation of oocytes after IVM for FP, cryopreservation of oocytes for FP, explanation of the procedures to patients, and recent research on FP using IVM were investigated.

Results

Although IVM for FP remains controversial, the application of FP is expected to expand. Depending on the age and disease status of the patient, various methods of oocyte collection and ovarian stimulation, as well as various needle types and aspiration pressures, have been reported. The maturation rate of IVM in FP ranges widely and requires optimization in the future. In regard to cryopreservation for matured oocytes, the vitrification method is currently recommended.

Conclusion

Regarding FP for patients with cancer, the treatment of cancer is prioritized; thus, the time and use of medicines are often constrained. As several key points regarding IVM remain unclear, well‐designed and specific counseling for patients is necessary.

Female fertility: is it safe to "freeze?"

Objective:

To evaluate the safety and risk of cryopreservation in female fertility preservation.

Data sources:

The data analyzed in this review were the English articles from 1980 to 2013 from journal databases, primarily PubMed and Google scholar. The criteria used in the literature search show as following: (1) human; embryo; cryopreservation/freezing/vitrification, (2) human; oocyte/immature oocyte; cryopreservation/ freezing/vitrification, (3) human; ovarian tissue transplantation; cryopreservation/freezing/vitrification, (4) human; aneuploidy/DNA damage/epigenetic; cryopreservation/freezing/vitrification, and (5) human; fertility preservation; maternal age.

Study selection:

The risk ratios based on survival rate, maturation rate, fertilization rate, cleavage rate, implantation rate, pregnancy rate, and clinical risk rate were acquired from relevant meta-analysis studies. These studies included randomized controlled trials or studies with one of the primary outcome measures covering cryopreservation of human mature oocytes, embryos, and ovarian tissues within the last 7 years (from 2006 to 2013, since the pregnancy rates of oocyte vitrification were significantly increased due to the improved techniques). The data involving immature oocyte cryopreservation obtained from individual studies was also reviewed by the authors.

Results:

Vitrifications of mature oocytes and embryos obtained better clinical outcomes and did not increase the risks of DNA damage, spindle configuration, embryonic aneuploidy, and genomic imprinting as compared with fresh and slow-freezing procedures, respectively.

Conclusions:

Both embryo and oocyte vitrifications are safe applications in female fertility preservation.

In-vitro maturation of germinal vesicle and metaphase I eggs prior to cryopreservation optimizes reproductive potential in patients undergoing fertility preservation

PURPOSE OF REVIEW

To evaluate current and previous findings related to a timely implementation of in-vitro maturation (IVM) of germinal vesicle, metaphase I and metaphase II oocytes with an optimal cryopreservation to determine whether IVM should be attempted prior to (fresh IVM) or IVM after cryopreservation (postthaw IVM). Mitochondrion, chromatin and spindle formation in both groups were interpreted from referenced studies to establish best management of all oocytes.

RECENT FINDINGS

The postthaw survival of germinal vesicle, metaphase I, fresh IVM-metaphase II and control metaphase II oocytes did not differ significantly [83.3% (n=9), 86.7% (n=12), 83% (n=57) and 86% (n=68), respectively]. Overall, combined survival and maturation were significantly higher (P<0.05) in the fresh IVM group at 63.8% (44 of 69) compared with the postthaw IVM group at 33.3% (nine of 27).

SUMMARY

Conservation of retrieved immature oocytes after vaginal oocyte retrieval has become a major concern for patients, as they strive to maximize the reproductive viability of all oocytes obtained during treatment. Oocyte cryopreservation is important for patients at risk of ovarian cancer, elective fertility preservation and potentially for ovum donation. The superior maturation rate of germinal vesicle and metaphase I oocytes in the fresh IVM vs. postthaw groups provides strong impetus to mature oocytes to the metaphase II stage prior to cryopreservation.

Evaluation of the impact of vitrification on the actin cytoskeleton of in vitro matured ovine oocytes by means of Raman microspectroscopy

PURPOSE

Investigation of the changes induced by vitrification on the cortical F-actin of in vitro matured ovine oocytes by Raman microspectroscopy (RMS).

METHODS

Cumulus-oocyte complexes, recovered from the ovaries of slaughtered sheep, were matured in vitro and vitrified following the Minimum Essential Volume method using cryotops. The cortical region of metaphase II (MII) oocytes (1) exposed to vitrification solutions but not cryopreserved (CPA-exp), (2) vitrified/warmed (VITRI), and (3) untreated (CTR) was analyzed by RMS. A chemical map of one quadrant of single CPA-exp, VITRI and CTR oocytes was, also, performed. In order to identify the region of Raman spectra representative of the cortical F-actin modification, a group of in vitro matured oocytes were incubated with latrunculin-A (LATA), a specific F-actin destabilizing drug, and processed for RMS analysis. Thereafter, all the oocytes were stained with rhodamine phalloidin and evaluated by fluorescence confocal microscopy. Raman spectra of the oocytes were, statistically, analyzed using Principal Component Analysis (PCA).

RESULTS

The PCA score plots showed a marked discrimination between CTR oocytes and CPA-exp/ VITRI groups. The main differences, highlighted by PCA loadings, were referable to proteins (1657, 1440 and 1300 cm(-1)) and, as indicated by LATA experiments, also included the changes of the F-actin. Analysis by confocal microscopy revealed a clear alteration of the cortical F-actin of CPA-exp and VITRI oocytes confirming RMS results.

CONCLUSIONS

Raman microspectroscopy may represent an alternative analytical tool for investigating the biochemical modification of the oocyte cortex, including the F-actin cytoskeleton, during vitrification of in vitro matured ovine oocytes.

Bisphenol-A and human oocyte maturation in vitro

STUDY QUESTION

Does exposure to bisphenol-A (BPA) affect the maturation of human oocytes in vitro?

SUMMARY ANSWER

There was a dose-response association of BPA exposure with altered human oocyte maturation in vitro.

WHAT IS KNOWN ALREADY

There is widespread exposure of the general population to BPA. BPA has been detected in the human follicular fluid. Animal studies have shown that BPA exposure is associated with maturation arrest and spindle abnormalities in maturing oocytes.

STUDY DESIGN, SIZE, DURATION

A randomized trial, using 352 clinically discarded oocytes from 121 patients.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study population was drawn from patients undergoing IVF/ICSI cycles in our program at Brigham and Women's Hospital from March 2011 to April 2012. Oocytes from only one cycle for each patient were included in the study. Cycles with at least two germinal vesicle stage oocytes were included with random allocation of one oocyte to culture for 30 h without BPA and remaining sibling oocytes to medium-containing BPA (20, 200 ng/ml or 20 µg/ml). Oocytes were fixed and labeled for tubulin, actin and chromatin and examined with immunofluorescence and confocal microscopy. Oocytes were assessed for meiotic stage (n = 292), and those at metaphase II (MII, n = 175) were further classified according to their spindle configurations and patterns of chromosome alignment. McNemar's test was used to compare dichotomized maturation status. Generalized estimating equations were used to account for the correlation between oocytes from the same woman and for the spindle analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

As the BPA dose increased, there was a decrease in the percentage of oocytes that progressed to MII (P = 0.002) and increases in the percentage of oocytes that were degenerated (P = 0.01) or that had undergone spontaneous activation (P = 0.007). Among MII oocytes, as the BPA dose increased, there was a significant trend (by test for trend) for a decreased incidence of bipolar spindles (P < 0.0001) and aligned chromosomes (P = 0.02).

LIMITATIONS, REASONS FOR CAUTION

Although we used sibling oocytes to overcome potential confounders, such as infertility diagnosis and maternal age, additional studies with a larger number of oocytes are required to confirm the present results. Having access only to clinically discarded oocytes, we were limited to evaluating only those oocytes that failed to mature in vivo despite having been exposed to gonadotrophin stimulation and the ovulatory trigger of HCG.

WIDER IMPLICATIONS OF THE FINDINGS

To our knowledge, this is the first study investigating the effect of BPA on oocyte meiotic maturation, spindle morphology and chromosome alignment in human oocytes. Together with prior animal studies, the data support the negative influences of BPA on cell cycle progression, spindle architecture and chromosome organization during oocyte maturation. Furthermore, the increased rates of abnormal maturation in oocytes exposed to BPA may be relevant to our understanding of the decrease in fertility reported in the last decades.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the NIEHS Center Grant Pilot Project (P30-ES000002). R.M. was sponsored by a fellowship from the Environmental Health Fund, Israel and by the Frederick L. Hisaw Endowment, Harvard School of Public Health. There are no conflicts of interest.

TRIAL REGISTRATION NUMBER

n/a.

Optimizing human oocyte cryopreservation for fertility preservation patients: should we mature then freeze or freeze then mature?

OBJECTIVE

To evaluate the maturation and post-thaw survival rates of immature oocytes to determine whether in vitro maturation (IVM) should be attempted prior to or after cryopreservation.

DESIGN

Nonrandomized observational study.

SETTING

Private academic and clinical reproductive center.

PATIENT(S)

Patients (n = 71) who donated immature unusable oocytes after vaginal oocyte retrieval (VOR) after undergoing controlled ovarian hyperstimulation using a standard GnRH antagonist protocol.

INTERVENTION(S)

Germinal vesicle (GV), metaphase I (MI), and metaphase II (MII) oocytes (n = 175) were obtained from consenting IVF patients for fresh IVM, post-thaw IVM, or control group. In the fresh IVM group, GV- and MI- stage oocytes (n = 69) were cultured for 24 hours, matured in vitro (IVM-MII), cryopreserved, thawed, and evaluated for survival. In the post-thaw IVM group, GV- and MI- stage oocytes (n = 27) were frozen on day 0, thawed, evaluated for survival, and cultured for 24-hour IVM. MII donor oocytes (n = 79) were cryopreserved and thawed as a control.

MAIN OUTCOME MEASURE(S)

Survival postfreeze and oocyte development to the MII stage was analyzed using a χ(2) analysis.

RESULT(S)

Fresh IVM had a significantly higher maturation rate than post-thaw IVM.

CONCLUSION(S)

Oocyte cryopreservation is important for patients at risk of ovarian cancer, elective fertility preservation, and, potentially, for ovum donation. The superior maturation rate of GV and MI oocytes in the fresh versus post-thaw groups provides strong evidence for maturing oocytes to the MII stage before cryopreservation.

Best practices of ASRM and ESHRE: a journey through reproductive medicine

BACKGROUND

The American Society for Reproductive Medicine (ASRM) and the European Society of Human Reproduction and Embryology (ESHRE) are the two largest societies in the world whose members comprise the major experts and professionals working in the field of reproductive medicine and embryology. These societies have never before had a joint scientific meeting.

METHOD(S)

A 3-day meeting was planned and took place in March of 2012. The goal was to present and debate key topics, as well as modes of practice in reproductive medicine and to discuss recent developments in the field.

RESULT(S)

Presentations by members of ASRM and ESHRE were of three types: 'state of the art' lectures, 'back-to-back' presentations of two points of view and debates.

CONCLUSION(S)

For the first time, ASRM and ESHRE held a joint meeting where a special emphasis was given to presentations on the hottest topics in the field. Although different opinions and approaches sometimes exist on the two sides of the Atlantic, an appreciation and acceptance of these differences was evident, and there was more commonality than divergence of opinion.

Best practices of ASRM and ESHRE: a journey through reproductive medicine

BACKGROUND

The American Society for Reproductive Medicine (ASRM) and the European Society of Human Reproduction and Embryology (ESHRE) are the two largest societies in the world whose members comprise the major experts and professionals working in the field of reproductive medicine and embryology. These societies have never before had a joint scientific meeting.

METHODS

A 3-day meeting was planned and took place in March of 2012. The goal was to present and debate key topics, as well as modes of practice in reproductive medicine and to discuss recent developments in the field.

RESULTS

Presentations by members of ASRM and ESHRE were of three types: 'state of the art' lectures, 'back-to-back' presentations of two points of view and debates.

CONCLUSIONS

For the first time, ASRM and ESHRE held a joint meeting where a special emphasis was given to presentations on the hottest topics in the field. Although different opinions and approaches sometimes exist on the two sides of the Atlantic, an appreciation and acceptance of these differences was evident, and there was more commonality than divergence of opinion.

Ultrastructure of human mature oocytes after vitrification

Since the introduction of human assisted reproduction, oocyte cryopreservation has been regarded as an attractive option to capitalize the reproductive potential of surplus oocytes and preserve female fertility. However, for two decades the endeavor to store oocytes has been limited by the not yet optimized methodologies, with the consequence of poor clinical outcome or of uncertain reproducibility. Vitrification has been developed as the promising technology of cryopreservation even if slow freezing remains a suitable choice. Nevertheless, the insufficiency of clinical and correlated multidisciplinary data is still stirring controversy on the impact of this technique on oocyte integrity. Morphological studies may actually provide a great insight in this debate. Phase contrast microscopy and other light microscopy techniques, including cytochemistry, provided substantial morpho-functional data on cryopreserved oocyte, but are unable to unraveling fine structural changes. The ultrastructural damage is one of the most adverse events associated with cryopreservation, as an effect of cryo-protectant toxicity, ice crystal formation and osmotic stress. Surprisingly, transmission electron microsco py has attracted only limited attention in the field of cryopreservation. In this review, the subcellular structure of human mature oocytes following vitrification is discussed at the light of most relevant ultrastructural studies.