Search Results (82)

With the continuous advancement in reproductive biology, oocyte vitrification has become a critical technology for preserving female germplasm and protecting it from environmental disruptions. This technique also eliminates temporal and spatial constraints in animal embryo engineering research. However, during the vitrification of animal oocytes, exposure to low temperatures and high concentrations of cryoprotectants can cause various forms of damage, including cytoskeletal disruption, spindle abnormalities, mitochondrial dysfunction, apoptosis, oxidative stress and epigenetic modifications. These issues are now understood to severely restrict the subsequent developmental competence of oocytes, resulting in lower cleavage and blastocyst formation rates than those of fresh oocytes. Currently, the mechanisms of cryodamage in vitrified oocytes remain poorly understood, and standardized strategies to enhance vitrification efficiency have yet to be firmly established. This review provides a formal overview of the physiological factors underlying oocyte sensitivity to vitrification, alongside the mechanisms of cryodamage and the variables influencing post-thaw survival and reproductive success. It evaluates strategies for mitigating vitrification-induced stress, compares interspecies differences, and addresses current research limitations. By identifying future directions, this review offers new insights for optimizing mammalian oocyte cryopreservation techniques. Full article

Background/Objectives: Women undergoing fertility preservation by oocyte vitrification before oncological treatments often have a poorer ovarian response to stimulation than healthy women. This indicates that cancer itself can adversely affect ovarian function. However, this impact remains unclear, and its underlying mechanisms are poorly understood. We investigated in this study whether breast cancer, the most common form of cancer in women of reproductive age, alters ovarian function by itself. Methods: For this purpose, we compared the ovarian response to hormonal stimulation in women with breast cancer undergoing oocyte cryopreservation with that in oocyte donors, adjusting for age and BMI. We analysed our data according to the molecular subtype of breast cancer, tumour grade, lymph node invasion, and BRCA1 mutation status. Secondly, we evaluated whether breast cancer alters cholesterol homeostasis in cumulus cells, given its essential role in oocyte quality. The expression of genes involved in cholesterol biosynthesis was analysed in cumulus cells using RT-qPCR, while the concentrations of cholesterol and its intermediates were quantified in follicular fluid using GC-FID and GC-MS/SIM. Results: Compared with oocyte donors, breast cancer patients exhibited a significant decrease in collected oocytes after stimulation. At the molecular level, our data revealed a significant deregulation of cholesterol biosynthesis gene expression in cumulus cells of women with breast cancer. The quantification of cholesterol and its intermediates in follicular fluid revealed altered concentrations in women with breast cancer, suggesting a disrupted follicular microenvironment. Conclusions: These findings suggest that breast cancer impairs ovarian function, at least in part, by disrupting cholesterol homeostasis, which can lead to reduced oocyte competence. Full article

Due to its high efficiency and safety, oocyte vitrification finds broad application in many fields of life sciences, such as clinical assisted reproduction and conservation of animal genetic resources. However, vitrification may cause cellular damage and reduce the quality of oocytes and their cumulus cells (CCs), which could be closely related to disorders in lipid metabolism. At present, the impact of vitrification upon the lipid profile of oocytes and CCs has not been systematically elucidated. In this study, we used porcine germinal vesicle cumulus–oocyte complexes (COCs) as a model to analyze their lipid characteristics after vitrification and in vitro maturation (IVM), utilizing untargeted lipid metabolomics. Our results showed that an overall count of 37 down-regulated and 8 up-regulated differential lipids was identified in the vitrified oocytes. Pathway analysis confirmed the enrichment in glycerophospholipid metabolism and fat digestion and absorption, etc. Combined with transcriptomic analysis, three enriched pathways were revealed, including the AMPK signaling pathway, metabolic pathways, and fatty acid elongation. On the other hand, a total of four down-regulated and eight up-regulated differential lipids were detected in the vitrified CCs. Pathway enrichment implicated autophagy, glycerophospholipid metabolism, etc. A joint analysis of metabolomic and transcriptomic data revealed four enrichment pathways, including cholesterol metabolism, fat digestion and absorption, regulation of lipolysis in adipocytes, and metabolic pathways. Notably, the supplementation of lysophosphatidylcholine during IVM attenuated oxidative stress, enhanced mitochondrial activity, and enhanced the viability and embryonic development of cryopreserved porcine oocytes. The results indicate that vitrification alters lipids in oocytes and CCs, and the supplementation of lipids plays a role in improving the quality of vitrified oocytes. Full article

This study aimed to evaluate the impact of coenzyme Q10 (CoQ10) supplementation during in vitro maturation (IVM) and/or vitrification of immature dromedary camel oocytes on their subsequent in vitro developmental competence. Additionally, total antioxidant capacity (TAC) and malondialdehyde (MDA) concentrations were assessed in the IVM spent medium. In experiment 1, cumulus–oocyte complexes (COCs, n = 808) collected from slaughtered dromedary camel ovaries were cultured in IVM media supplemented with either 0, 25, 50, or 100 μM CoQ10 for 36 h. Matured oocytes were then fertilized in vitro with epididymal camel spermatozoa. Eighteen hours post-insemination (pi), presumptive zygotes were cultured in vitro for 7 days. In experiment 2, a total of 875 COCs were randomly allocated to one of four experimental groups, namely (a) Vit−/IVM− (control) group, where COCs were vitrified in vitrification solution (VS; 25% DMSO + 25% EG) and matured in IVM media without CoQ10 supplementation; (b) Vit+/IVM− group, in which COCs were vitrified in a VS supplemented with 50 µM CoQ10 and matured in IVM media without CoQ10 supplementation; (c) Vit−/IVM+ group, where COCs were vitrified in VS without CoQ10 supplementation and matured in IVM media supplemented with 50 µM CoQ10; and (d) Vit+/IVM+ group, where COCs were vitrified in VS and matured in IVM media, both supplemented with 50 µM CoQ10. Following vitrification and warming, oocyte viability was evaluated morphologically and by trypan blue staining. Viable oocytes were then matured, fertilized, and cultured in vitro. In experiment 3, TAC and MDA concentrations in the IVM spent media were analyzed. Results showed that 50 µM CoQ10 supplementation to IVM media enhanced cumulus expansion, nuclear maturation, cleavage, and blastocyst rates (experiment 1). Adding 50 µM CoQ10 to the VS enhanced (p ≤ 0.05) oocyte viability compared to those vitrified in CoQ10-free media. Cumulus cell expansion and nuclear maturation rates were higher (p ≤ 0.05) in Vit−/IVM+ than in Vit+/IVM+ and Vit−/IVM− groups. Furthermore, cleavage and blastocyst rates were the highest (p ≤ 0.05) in Vit−/IVM+ group (experiment 2). The concentrations of TCA were higher, and the concentrations of MDA were lower (p ≤ 0.05) in Vit−/IVM+ than in other groups (experiment 3). In conclusion, supplementation of CoQ10 in the maturation medium of vitrified–warmed immature dromedary camel oocytes may enhance their in vitro developmental competence. Full article

To improve the vitrification efficiency of bovine germinal vesicle (GV) oocytes, the use of hydroxyapatite (HA) nanoparticles as a novel cryopreservation additive represents a promising approach. This study aimed to investigate the effects of HA nanoparticles and permeable cryoprotective agents (CPAs) on the ultrastructure, developmental competence, and gene expression of bovine GV oocytes following vitrification. Oocytes were vitrified in vitrification solutions containing HA nanoparticles of different sizes (20, 40, or 60 nm) and concentrations (0.01%, 0.05%, or 0.1%) to determine the optimal conditions based on survival rate, mitochondrial membrane potential (MMP) level, and developmental competence. Subsequently, the synergistic effects of HA nanoparticles and permeable CPAs (VS: 20% EG + 20% DMSO; VS1: 17.5% EG + 17.5% DMSO) were further evaluated. The optimal treatment (40 nm 0.05% HA nanoparticles) significantly increased MMP level, and improved developmental competence compared with the vitrified control group (p < 0.05). Among the vitrified groups, vitrified oocytes in the VS1-HA group (combining HA nanoparticles with reduced concentrations of permeable CPAs) exhibited the highest MMP level (1.89), maturation rate (50.39%), cleavage rate (27.07%), and blastocyst rate (10.53%) (p < 0.05). Ultrastructural analysis further revealed that the VS1-HA group maintained more intact zona pellucida structures and showed reduced mitochondrial swelling compared with the vitrified control group. Moreover, the expression levels of genes associated with zona pellucida formation (ZP3), mitochondrial fusion (MFN1), and chromatin remodeling (NPM2) were significantly upregulated in the VS1-HA group relative to the vitrified control group. Overall, these findings indicate that the combination of HA nanoparticles with lower concentrations of permeable CPAs enhances MMP level, alleviates vitrification-induced ultrastructural damage, and upregulates the expression of key developmental genes, thereby improving the developmental competence of vitrified bovine GV oocytes. Full article

Oocyte vitrification imposes oxidative stress that compromises maturation competence. Aquaporin-7 (AQP7) has been implicated in cellular redox regulation, but its specific role in cryopreserved oocytes remains unclear. Here, germinal vesicle (GV) stage oocytes were vitrified and warmed with AQP7 inhibitor Z433927330 (0.5, 5, 50 μM). AQP7 inhibition disrupted redox balance, compromised mitochondrial function. Consequently, it severely compromised developmental competence, leading to significantly reduced cleavage (39.90% ± 6.17 vs. 52.93% ± 3.37) and blastocyst formation rates (1.67% ± 2.89 vs. 5.17% ± 2.49) in vitro. To confirm, we performed microinjection-mediated AQP7 knockdown and overexpression and assessed their effects on maturation. AQP7 knockdown further reduced the maturation rate of vitrified oocytes (20.22% ± 3.14 vs. 36.31% ± 2.10), whereas overexpression partially restored it (43.98% ± 4.71 vs. 33.74% ± 2.21). The mitochondrial-targeted antioxidant MitoQ partially rescued the maturation rate (53.13% ± 2.75 vs. 43.52% ± 2.71). Thus, AQP7 is essential for the maturation of vitrified sheep oocytes by safeguarding intracellular redox homeostasis, thereby preventing mitochondrial dysfunction and cytoskeletal damage, and loss of embryonic developmental potential. Full article

Dimethyl sulfoxide (DMSO) is widely utilized in the vitrification of oocytes, but DMSO exhibits concentration-dependent toxicity, which can compromise oocyte developmental potential by disrupting key cellular processes. This study reports the first successful use of cold shock protein B (CspB protein) as a substitute for DMSO in vitrification solutions for oocyte vitrification. Combining dynamics simulations and experimental validation, we demonstrated CspB’s ability to inhibit ice crystallization and recrystallization by stabilizing its position at the ice–water interface and reducing ice formation rates. Recombinant CspB was successfully expressed and shown to bind to the oolemma. In vitrification solutions, CspB (1–2 mg/mL) effectively reduced ice crystal size and enabled a significant reduction or complete replacement of DMSO. This strategy markedly improved the post-thaw survival rates of both mouse and bovine metaphase II (MII) oocytes. Furthermore, oocytes vitrified with an optimized formulation (15% ethylene glycol + 2 mg/mL CspB) exhibited developmental competence (cleavage and blastocyst rates), oxidative stress markers (ROS, GSH), mitochondrial function (membrane potential and content), and apoptosis levels (Caspase-3/9) comparable to those treated with a standard DMSO-containing system. Transcriptomic analysis revealed that CspB’s cryoprotection involves the modulation of the mTOR signaling pathway. This role was functionally confirmed, as activation of mTOR abolished CspB’s beneficial effects, reinstating oxidative damage, mitochondrial dysfunction, and apoptosis. Thus, the CspB protein replaces DMSO with direct ice crystal formation suppression and mTOR-mediated oxidative stress regulation. This study offers a protein-based alternative to conventional permeable cryoprotectants. This approach holds promise for improving reproductive biotechnologies across species. Full article

With increasing life expectancy driven by rapid biomedical science advancement, reproductive longevity has become a key concept in women’s health. Preventing reproductive senescence is important not only to extend fertility potential but also to preserve endocrine health, enhance quality of life, and promote healthy aging. The end of ovarian function and fertility is symbolized by menopause, as the most eminent index of reproductive aging. Hormone replacement therapy (HRT) remains the mainstay for managing menopausal symptoms. However, as the use of HRT is often limited, there is a need for safe and effective alternatives. This narrative review summarizes current and emerging approaches targeting different stages of reproductive aging. Both hormonal and non-hormonal therapies for vasomotor and genitourinary symptoms are discussed alongside developing fertility preservation techniques, including oocyte vitrification, ovarian tissue cryopreservation, in vitro follicle maturation, and artificial ovary engineering. Furthermore, evolving and experimental ovarian regenerative strategies, such as stem cell transplantation, intraovarian platelet-rich plasma (PRP) injections, antioxidants, metabolic modulators, telomerase activators, and stem cell-derived extracellular vesicles, offer new prospects for delaying or reversing ovarian aging. Overall, personalized regenerative strategies and innovative solutions may reshape the future of women’s reproductive health and longevity. Full article

The preservation of porcine oocytes is critically important for advancing superior breeds and conserving genetic resources in pig production. Vitrification has gained traction as a preferred alternative to slow freezing for porcine oocytes because of its effectiveness in reducing ice crystal formation, yet it can still negatively affect oocyte quality, compromising their in vitro maturation (IVM) and later embryonic development. Long non-coding RNAs (lncRNAs) have proven to be key players in numerous biological processes, such as oocyte growth, maturation, and early embryogenesis. Despite this, the effects of vitrified porcine germinal vesicle (GV) oocytes, particularly regarding IVM and the dynamic expression patterns of lncRNAs during embryonic development, remain largely unclear. To address this gap, this study conducted lncRNA sequencing at the metaphase II (MII), parthenogenetic 4-cell embryo, and parthenogenetic blastocyst stages sourced from both fresh and vitrified GV oocytes. This method enabled us to ascertain the impact of vitrification on lncRNA expression throughout oocyte maturation and embryonic development. Results identified 773 differentially expressed lncRNAs (DELs) at the MII stage, 1973 at the parthenogenetic 4-cell, and 1192 at the parthenogenetic blastocyst. Enrichment analysis of forecasted target genes revealed their involvement in key regulatory pathways associated with the cell cycle, meiosis, stress response, and metabolic activity. Overall, this study provides a comprehensive overview of lncRNA expression during oocyte maturation and embryonic development following porcine GV oocyte vitrification, thereby shedding light on the molecular mechanisms behind vitrification-induced damage. Full article

Fertility-sparing treatments (FSTs) have gained importance for young female cancer patients, especially those with early-stage cervical, ovarian, and endometrial cancers. However, concerns about the long-term safety of these procedures, particularly in more advanced cancers, persist. A literature review was conducted using databases such as PubMed, Scopus, and Web of Science. The search terms included “fertility preservation” and “gynaecological cancer”. Articles published between 2014 and 2024 were considered, with 39 articles cited in the paper. The inclusion criteria were female patients undergoing FST. Studies were excluded if prior treatments impacted fertility or if oncological outcomes were inadequately reported. Radical trachelectomy, laparoscopic fertility-sparing surgeries, and cryopreservation techniques, such as ovarian tissue vitrification and oocyte cryopreservation, offer viable options for preserving fertility in early-stage gynecological cancer patients. Radical trachelectomy and cryopreservation showed positive reproductive outcomes, with pregnancy rates of 30–50% in early-stage cases. GnRH analogs during chemotherapy also demonstrated benefits in maintaining fertility. Despite these advances, recurrence in more advanced stages (FIGO IA2 and beyond) remains a concern. Minimally invasive surgeries like robotic-assisted procedures demonstrated comparable fertility outcomes to traditional methods but with fewer complications. FST is a promising option for women with early-stage cancer, offering favorable reproductive and survival outcomes. However, further research is needed to confirm long-term oncological safety in advanced stages. Multidisciplinary approaches and individualized treatment planning are essential for optimizing outcomes. Full article

The aim was to evaluate the effectiveness of semen cryopreservation and oocyte vitrification in roe deer as a potential method of gamete preservation for endangered deer species. Sperm were isolated from the cauda epididymis of fourteen bucks (n = 14). The motility measure (CASA) and morphology of fresh semen (FS) and frozen–thawed semen (TS) were compared. A hyaluronic binding assay was used to distinguish between mature FS spermatozoa expressing hyaluronan receptors and immature FS lacking these receptors, and the mitochondrial membrane potential (MMP) in TS was determined (flow cytometry). A Sperm–Hyaluronan Binding Assay (HBA) showed a viability rate of 61.9% in FS and 78.2% in TS. Oocytes received from eight does (n = 8) underwent a viability test and vitrification, and fresh oocytes from the other eight does (n = 8) were fertilized with TS and embryos were cultured until the blastocyst stage. The number of isolated oocytes, cumulus–oocyte complexes (COCs), cleaved embryos, and expanded blastocysts was evaluated. Higher percentages of morphological factors (acrosome, head, midpiece, and tail shape) were observed in FS compared to TS, whereas the motility and progressive movement were greater in TS (p ≤ 0.001). The viability was 50.5% and MMP was 40.6% in TS. A total of 311 oocytes were collected and from 150 COCs and 125 blastocysts developed. The viability of thawed oocytes after vitrification was 81%. The viability of vitrified oocytes and cryopreserved sperm confirmed the effectiveness of freezing protocols and highlights the potential for their implementation in other deer species. Full article

Background/Objectives: Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare autoimmune disorder caused by mutations in the AIRE gene. Approximately 60% of affected females develop premature ovarian insufficiency (POI) by age 30, often most commonly due to steroidogenic autoantibodies. Although APECED is typically diagnosed in childhood, its reproductive implications are underrecognized. This study reports a case of successful fertility preservation in an adult woman with APECED and reviews the relevant literature. Methods: We describe the clinical course of a 37-year-old woman with genetically confirmed APECED who underwent ovarian stimulation for fertility preservation. A comprehensive PubMed search was also conducted to identify English-language case reports on fertility preservation in APECED-associated POI. Results: The patient experienced menarche at age 13, adrenal insufficiency at 14, and menstrual irregularities from age 18. Genetic analysis confirmed an AIRE mutation (NM_000383: exon 11: c.1400+1G>A). Given her relatively high anti-Müllerian hormone level, she opted for fertility preservation and underwent six cycles of ovarian stimulation, resulting in the cryopreservation of 17 mature oocytes. During ovarian stimulation, multiple follicular developments were observed, but serum E2 levels remained low. The literature review identified fewer than 20 reported cases addressing fertility preservation in APECED, highlighting its rarity and the lack of standardized management. Conclusions: Although APECED frequently leads to early POI due to impaired steroidogenesis, residual ovarian function may persist. Early assessment of ovarian reserve and timely fertility counseling are crucial, even in asymptomatic patients or those diagnosed in childhood. Reproductive planning should be integrated into the long-term care of women with APECED. Full article

Background/Objectives: Cellular oxidative stress is crucial for GV stage oocyte vitrification quality. PI3K and the aquaporin family have been shown to facilitate various cellular processes related to redox homeostasis and energy balance; yet, the mechanisms underlying the involvement of aquaporin 7 (AQP7) in vitrified oocyte oxidative stress remain unclear. The purpose of the present investigation was to evaluate the role of AQP7 in vitrified oocytes and the mechanisms involved. Methods: AQP7 inhibitors were employed to investigate the effect of AQP7 on oxidative stress in mouse-vitrified oocytes, whereas PI3K activators were harnessed to ascertain whether AQP7 serves as a functional molecule involved in this process. Results: Our results indicate that AQP7 inhibition in vitrified oocytes results in a significant decrease in glutathione (GSH) levels associated with cellular oxidation and an elevation in H₂O₂ levels. This was accompanied by exacerbated mitochondrial dysfunction, weakened cytoskeletal proteins, accelerated early apoptosis. Consequently, both survival and maturation rates were markedly reduced. Interestingly, PI3K/AKT activation increased AQP7 expression, restored abnormal mitochondrial distribution, as well as calcium homeostasis, and rescued the oocyte survival/maturation rate. Conclusions: Our results provide new insights indicating that PI3K/AKT/AQP7 decreases oxidative stress by regulating mitochondrial morphology, function, and distribution, thereby rescuing oocyte maturation in vitrification. Full article

This study compared the DuoStim protocol with two conventional follicular phase stimulations for vitrified oocyte accumulation in poor-prognosis patients undergoing PGT-A. A retrospective analysis of 112 IVF cycles was conducted, with 66 cycles among patients undergoing DuoStim (DS-Group) and 46 among patients undergoing conventional follicular phase stimulations (DF-Group). The primary outcome was the time to live birth, while secondary outcomes included clinical pregnancy rate, miscarriage rate, live birth rate, and cumulative live birth rate. The final analysis included 66 patients in the DS-Group and 40 in the DF-Group, as 6 women (13%) in the DF-Group discontinued treatment after the first stimulation. Oocyte yield was similar between groups (8.4 ± 3.9 in DS-Group vs. 8.2 ± 4.0 in DF-Group, p = 0.80), as was the number of euploid blastocysts (0.9 ± 1.2 vs. 1.1 ± 1.1, p = 0.37). The cumulative live birth rate was 22.7% in the DS-Group and 25% in the DF-Group (multivariate odds ratio adjusted for maternal age and male factor: 1.05, p = 0.93). The time to live birth was significantly shorter in the DS-Group (81.5 ± 15.5 days) compared to the DF-Group (153.7 ± 78.2 days, p < 0.001). DuoStim showed similar efficacy but a shorter time to live birth. Full article

This study aimed to compare the morphometry, morphology, and maturation capacity of cattle oocytes subjected to vitrification using different vitrification and maturation media. In Experiment 1, a total of 900 oocytes were divided into three groups: (1) matured before vitrification, (2) non-vitrified, and (3) vitrified as immature oocytes using the straw vitrification method. Morphometric parameters, including oocyte diameter, ooplasm, zona pellucida width (ZPW), granulosa cell width (GRSW), and zona pellucida-granulosa cell width (ZP GRSW), were measured (µm) before and after cryopreservation. In Experiment 2, the maturation capacity of three in vitro maturation (IVM) media (VitroMat-Protect™, BO-IVM™, and TCM199) was evaluated based on cumulus–oocyte complex (COC) expansion and polar body (PB) extrusion. Morphological abnormalities such as fragmented polar bodies (FPBs), large vacuoles (LVs), degenerated oocytes (DOs), and cracked cytoplasm (CC) were recorded. While vitrification did not significantly affect the oocyte diameter, ooplasm, or ZPW, it significantly reduced the GRSW and ZP GRSW. BO-IVM™ supported the highest COC expansion rate, while TCM199 had the lowest. Among vitrified oocytes, the highest PB extrusion rates were observed in BO-IVM^TM (35.14 ± 5.01) and Vitromat-Protect^TM (24.60 ± 5.67) as compared to TCM199 (18.44 ± 8.00; p < 0.05). Oocytes with higher CC rates were observed in VitroMat-Protect™ (24.50 ± 10.53) and BO-IVM™ (31.42 ± 7.32) as compared to TCM199 (18.70 ± 7.04). In conclusion, the vitrification process affects the granulosa cells in both vitrified immature and mature oocytes. BO-IVM^TM and VitroMat-Protect^TM supported better oocyte maturation than TCM199, although vitrification increased FPB and CC rates. Full article