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Vitrification, is an ultra-rapid, manual cooling process that produces glass-like (ice crystal-free) solidification. Water is prevented from forming intercellular and intracellular ice crystals during cooling as a result of oocyte dehydration and the use of highly concentrated cryoprotectant. Though oocytes can be cryopreserved without ice crystal formation through vitrification, it is still not clear whether the process of vitrification causes any negative impact (temperature change/chilling effect, osmotic stress, cryoprotectant toxicity, and/or phase transitions) on oocyte quality, which translates to diminished embryo developmental potential or subsequent clinical outcomes. In this review, we attempt to assess the technique's potential effects and the consequence of these effects on outcomes. Summary Sentence: The osmolarity changes and water movement during oocyte vitrification and warming procedures are illustrated. Graphical Abstract

PurposeThe main purpose and research question of the study are to compare the efficacy of high-security closed versus open devices for human oocytes’ vitrification.MethodsA prospective randomized study was conducted. A total of 737 patients attending the Infertility and IVF Unit at S.Orsola University Hospital (Italy) between October 2015 and April 2020 were randomly assigned to two groups. A total of 368 patients were assigned to group 1 (High-Security Vitrification™ - HSV) and 369 to group 2 (Cryotop® open system). Oocyte survival, fertilization, cleavage, pregnancy, implantation, and miscarriage rate were compared between the two groups.ResultsNo statistically significant differences were observed on survival rate (70.3% vs. 73.3%), fertilization rate (70.8% vs. 74.9%), cleavage rate (90.6% vs. 90.3%), pregnancy/transfer ratio (32.0% vs. 31.8%), implantation rate (19.7% vs. 19.9%), nor miscarriage rates (22.1% vs. 21.5%) between the two groups. Women’s mean age in group 1 (36.18 ± 3.92) and group 2 (35.88 ± 3.88) was not significantly different (P = .297). A total of 4029 oocytes were vitrified (1980 and 2049 in groups 1 and 2 respectively). A total of 2564 were warmed (1469 and 1095 in groups 1 and 2 respectively). A total of 1386 morphologically eligible oocytes were inseminated by intracytoplasmic sperm injection (792 and 594 respectively, P = .304).ConclusionsThe present study shows that the replacement of the open vitrification system by a closed one has no impact on in vitro and in vivo survival, development, pregnancy and implantation rate. Furthermore, to ensure safety, especially during the current COVID-19 pandemic, the use of the closed device eliminates the potential samples’ contamination during vitrification and storage.

Increasing numbers of women are undergoing oocyte or tissue cryopreservation for medical or social reasons to increase their chances of having genetic children. Social egg freezing (SEF) allows women to preserve their fertility in anticipation of age-related fertility decline and ineffective fertility treatments at older ages. The purpose of this study was to summarize recent findings focusing on the challenges of elective egg freezing. We performed a systematic literature review on social egg freezing published during the last ten years. From the systematically screened literature, we identified and analyzed five main topics of interest during the last decade: (a) different fertility preservation techniques, (b) safety of freezing, (c) usage rate of frozen oocytes, (d) ethical considerations, and (e) cost-effectiveness of SEF. Fertility can be preserved for non-medical reasons through oocyte, embryos, or ovarian tissue cryopreservation, with oocyte vitrification being a new and optimal approach. Elective oocyte cryopreservation is better accepted, supports social gender equality, and enhances women’s reproductive autonomy. Despite controversies, planned oocyte cryopreservation appears as a chosen strategy against age-related infertility and may allow women to feel that they are more socially, psychologically, and financially stable before motherhood.

Abstract PurposeTo report the case of a young woman diagnosed with Turner syndrome (TS) who achieved a live birth using her own oocytes that had been vitrified for fertility preservation.MethodsA 25-year-old woman with mosaic (45,X/46,XX) TS was referred for fertility preservation (FP) counseling. Serum anti-Müllerian hormone (AMH) level was normal (6.4 µg/L). In view of the unpredictable rate of follicle loss in TS individuals, she requested FP and underwent two cycles of ovarian stimulation (OS) for oocyte cryopreservation (OoC) using a GnRH antagonist protocol and recombinant follicle stimulating hormone (rFSH), 200–250 IU daily for 8 resp. 12 days.ResultsIn total, 29 metaphase II oocytes (MII) were vitrified after OS. After conceiving spontaneously and achieving a live birth, she returned to the clinic five years after OoC with a desire for pregnancy using in vitro fertilization (IVF) of her cryopreserved oocytes and preimplantation genetic testing (PGT-A). All 29 MII oocytes were thawed; 23 oocytes survived (79.3%) and were inseminated with partner sperm using intracytoplasmic sperm injection (ICSI). Thirteen oocytes were fertilized resulting in three good quality blastocysts which were vitrified after trophectoderm biopsy for PGT-A using array-CGH. Two blastocysts were found to be euploid. One was thawed and transferred to the uterus using a HRT priming protocol. An uneventful pregnancy occurred. The patient delivered a healthy baby girl weighing 3490 g at 40 weeks of gestation.ConclusionsWe report the first live birth achieved using cryopreserved oocytes in a woman diagnosed with mosaic TS. Cryopreservation of oocytes after ovarian stimulation is a realistic option for FP in selected post menarche individuals with mosaic TS. Whether PGT-A may reduce the risk of pregnancy loss in TS has to be confirmed by further studies.

PurposeAlthough recent in vitro maturation (IVM) studies in pediatric patients have demonstrated successful retrieval and maturation of oocytes, the studies included only a small number of premenarchal patients. In the present study, we examined the potential use of oocyte retrieval and maturation for pediatric patients who undergo ovarian tissue cryopreservation (OTC).MethodsWe retrospectively examined the clinical records of pediatric patients who underwent OTC at our institution between October 2015 and December 2022. Data on the age, primary disease, menstrual history, pre-procedure chemotherapy, anti-Müllerian hormone (AMH) level, number of oocytes collected ex vivo from ovarian tissue, and number of mature oocytes from IVM were examined.ResultsData of 60 pediatric patients (aged 1 to 17 years) were included for analysis. Oocytes were retrieved from 36 patients; the oocytes of 18 of these patients could be cryopreserved. The IVM rate was significantly lower in the premenarchal patients than in the postmenarchal patients. The number of mature oocytes retrieved from IVM was higher in the no-chemotherapy group than in the chemotherapy group. A significant positive correlation was observed between the AMH level and the IVM outcomes.ConclusionOocyte retrieval and maturation in pediatric patients undergoing OTC is particularly useful in those not receiving chemotherapy. In patients receiving chemotherapy, the AMH level may be useful for predicting the IVM outcome. Activation of the oocyte maturation process in vivo in pediatric patients and better understanding of the major regulators of oocyte maturation are necessary to improve the utility of the IVM procedure.

Purpose The efficacy of oocyte cryopreservation still requires enhancement. Current understanding of cryodamage is largely limited to the organelle level, and the impact of freezing on oocyte gene expression remains unclear. Methods In this study, we employed an innovative dual-omics approach to assess the transcriptional and translational profiles of mouse metaphase II (MII) oocytes during the initial 4 h post-thaw. Results Our mapping of the translational recovery in vitrified mouse oocytes post-thaw revealed a critical 2-h window that is optimal for recovery. We confirmed the mitochondrial damage associated with vitrification and identified the activation of autophagy and proteasomal degradation during this period. Additionally, our analysis indicates that vitrified oocytes have another repair response to counteract cryoinjury, involving spindle remodeling and membrane recycling. Conclusions These findings can guide future efforts to improve oocyte vitrification outcomes by improving repair processes and not focusing solely on the damage processes.

PurposeTo evaluate embryo ploidy in a cohort of patients who underwent preimplantation genetic testing for aneuploidy (PGT-A) with vitrified oocytes compared to fresh oocytes.MethodsPatients who underwent their first autologous oocyte vitrification and warming followed by in vitro fertilization (IVF) and trophectoderm biopsy for PGT-A between 1/1/2017 and 12/31/2021 at a single academic institution were included. Patients were compared 1:3 to age-matched controls who underwent their first IVF cycle with fresh oocytes and subsequent trophectoderm biopsy for PGT-A. The primary outcome was the proportions of euploid, mosaic, and aneuploid embryos between those using vitrified versus fresh oocytes.Results117 patients who cryopreserved a total of 1,272 mature oocytes were included in the study and were matched with 351 controls using fresh oocytes. The average age was 36.9 ± 2.6 years, and the median interval between oocyte vitrification and warming was 38 months. There were similar numbers of mature oocytes (10.9 ± 4.9 vs. 11.1 ± 6.3, P = .67), fertilized oocytes (7.8 ± 4.0 vs. 8.7 ± 5.5, P = .10), and blastocysts per patient (5.1 ± 3.1 vs. 5.8 ± 4.3, P = .10) between those using vitrified versus fresh oocytes. In terms of embryo ploidy results, there were no statistically significant differences in rates of euploidy (40.1% vs. 41.6%), mosaicism (15.7% vs. 12.0%), or aneuploidy (44.3% vs. 46.4%) (P = .06) between the two groups.ConclusionsOocyte vitrification with subsequent warming, fertilization, and trophectoderm biopsy for PGT-A was not associated with adverse chromosomal competence when compared to age-matched controls utilizing fresh oocytes.

Purpose Fertility preservation in women with cancer represents a major medical challenge at the intersection of oncological and reproductive concerns. With therapeutic advancements, the survival rates of cancer patients have significantly improved, offering the possibility of motherhood. Currently, there is a lack of data on the return of cryopreserved oocytes/embryos and pregnancy outcomes following cancer treatment. Methods We conducted a retrospective, single-center, descriptive cohort study, including women who underwent fertility preservation through oocyte or embryo cryopreservation before a medium risk of gonadotoxicity chemotherapy for cancer at our Department of Reproductive Medicine and Oncofertility between January 2012 and May 2024. Results A total of 327 women were included, with 318 cases of oocyte cryopreservation and nine embryo cryopreservation. The average follow-up duration was 5.1 ± 2.7 years. Among the 49 women who expressed a desire for pregnancy post-cancer treatment, 65.3% of them ( n  = 32/49) reported at least one live birth. Of the 35 live births recorded, 80% (n = 28/35) resulted from spontaneous pregnancies, five were achieved after thawing vitrified oocytes (11.4%), and three after oocyte donation (8.6%). The return rate of cryopreserved oocytes was 6.92% (22/318), with a live birth rate per woman of 22.7% (5/22) following oocyte warming. Conclusion Although fertility preservation (FP) must be proposed systematically in age-reproductive women facing cancer with a medium risk of gonadotoxicity chemotherapy, physicians must be aware of the low rate of oocyte return and the potential for spontaneous pregnancies despite a post-cancer diminished ovarian reserve. Fertility consultations should also be better integrated into oncologic post-treatment care.

Vitrification has been widely used for oocyte cryopreservation, but there is still a need for optimization to improve clinical outcomes. In this study, we compared the routine droplet merge protocol with modified multi-gradient equilibration vitrification for cryopreservation of mouse oocytes at metaphase II. Subsequently, the oocytes were thawed and subjected to intracytoplasmic sperm injection (ICSI). Oocyte survival and spindle status were evaluated by morphology and immunofluorescence staining. Moreover, the fertilization rates and blastocyst development were examined in vitro . The results showed that multi-gradient equilibration vitrification outperformed droplet merge vitrification in terms of oocyte survival, spindle morphology, blastocyst formation, and embryo quality. In contrast, droplet merge vitrification exhibited decreasing survival rates, a reduced proportion of oocytes with normal spindle morphology, and lower blastocyst rates as the number of loaded oocytes increased. Notably, when more than six oocytes were loaded, reduced oocyte survival rates, abnormal oocyte spindle morphology, and poor embryo quality were observed. These findings highlight that the vitrification of mouse metaphase II oocytes by the modified multi-gradient equilibration vitrification has the advantage of maintaining oocyte survival, spindle morphology, and subsequent embryonic development.

PurposeTo investigate the developmental competence of ovarian tissue oocytes from patients with gynecological tumors using a biphasic in vitro maturation system with capacitation (CAPA-IVM) in comparison with standard IVM.MethodsThis sibling pilot study included 210 oocytes in 10 patients with gynecological malignancies. After ovariectomies, ovaries were cut into even halves and immature cumulus-oocyte complexes (COCs) were retrieved from the ovarian tissue. COCs were separately cultured in either a biphasic CAPA-IVM system for 53 h or in standard IVM for 48 h. After IVM, all COCs were denuded and mature oocytes were either vitrified (N=5) or used for ICSI (N=5). Embryos were cultured for 5–6 days and obtained blastocysts were vitrified.ResultsUse of the CAPA-IVM system led to a higher meiotic maturation rate in ovarian tissue oocytes (OTO) compared to standard IVM (56 vs 35%, p=0.0045) and had a tendency to result in lower degeneration after IVM. Only the CAPA-IVM method supported blastocyst formation.ConclusionsThe biphasic in vitro maturation system improved the competence of OTO in comparison to the standard IVM method. The study suggests that fertility preservation programs could become more efficient using IVM after capacitation culture.