Beyond Survival Effects of Vitrification-Warming on Epigenetic Modification and Maternal Transcripts of Oocytes

Oocyte vitrification-warming is a worldwide used technique for human fertility preservation. The question of whether the potential risk is associated with this specific procedure remains unresolved. As a fundamental factor of development, oocytes play an important role in early embryonic development, including epigenetic reprogramming and maternal-to-zygotic transition (MZT), that can develop to term. Vitrification, as a significant stressor, appears to have a significant impact on epigenetic modifiers and maternal transcripts of the oocyte, which ultimately results in lower developmental potential. Due to the rapidly evolving single-cell multi-omics sequencing, there have been many advances in this field. We will discuss recent progress in the impact of oocyte vitrification on epigenetic modification and maternal transcripts in this manuscript, hoping to provide a theoretical basis for the optimization and improvement of vitrification-warming technology

The case for mild stimulation for IVF: recommendations from The International Society for Mild Approaches in Assisted Reproduction.

The practice of ovarian stimulation for IVF is undergoing a fundamental re-evaluation as recent data begin to successfully challenge the traditional paradigm that ovarian stimulation should be aimed at the retrieval of as many oocytes as possible, in the belief that this will increase pregnancy rates. An opposing view is that live birth rate should not be the only end-point in evaluating the success of IVF treatment and that equal emphasis should be placed on safety and affordability. The International Society for Mild Approaches in Assisted Reproduction (ISMAAR) committee has carried out an up-to-date literature search, with the evidence being graded according to the University of Oxford's Centre for Evidence-Based Medicine. The recommendations were formulated taking into account the quality of evidence on the efficacy, risk and cost of each intervention. ISMAAR recommends adopting a mild approach to ovarian stimulation in all clinical settings as an increasing body of evidence suggests that mild stimulation is as effective as conventional stimulation, while being safer and less expensive. Mild ovarian stimulation could replace conventional stimulation, thus making IVF safer and more accessible worldwide

Effects of essential and non-essential amino acids on in-vitro maturation, fertilization and development of immature bovine oocytes

Background: Addition of amino acids to the culture medium is beneficial for embryonic development in many species. Objective: The objective of this study was to investigate the effects of amino acids on the in vitro maturation and embryonic development of the bovine oocyte. Materials and Methods: Bovine ovaries were collected from a local abattoir and brought into laboratory. Cumulus-oocyte complexes (COCs; n=1212) were aspirated from follicles (2-8 mm in diameter) and randomly assigned to four groups for maturation in culture: (1) Basic medium alone as control; (2) Basic medium supplemented with 2% MEM essential amino acids solution; (3) Basic medium supplemented with 1% MEM non-essential amino acids solution; and (4) Basic medium supplemented with 2% MEM essential amino acids solution + 1% MEM non-essential amino acids solution. COCs were incubated in 1 ml maturation medium in an Organ culture dish at 38.5°C in an atmosphere of 5% CO2 with high humidity. After 24 h of culture, 372 oocytes were fixed to determine maturation rate and the remaining oocytes were used for in vitro fertilization (IVF). Following 18 h of insemination, 437 oocytes were fixed and examined for fertilization and 403 oocytes were further cultured. Results:There were no differences in maturation rates and penetration rates among the four groups. Although oocyte cleavage rates were not different in the four groups, embryo development up to the 8-cell stage and blastocyst were significantly higher (p<0.05) in Group (2) and (4) than in the Control and Group (3). Conclusion: These results indicate that the presence of amino acids, especially essential amino acids in the maturation medium is beneficial to oocyte cytoplasmic maturation and subsequent early embryo development in vitro

Mitochondrial Dysfunction and Age - related Oocyte Quality

Fertility disorders have become a growing problem worldwide. It is well known that female fertility decreases with age, previous studies suggested that the age-related decline in female fertility potential was largely due to decrease in oocyte quality and mitochondrial dysfunction. Mitochondria play a crucial role during the process of oocyte maturation. Mitochondrial genetic, numerical and structural defects occur in oocyte aging process, mitochondrial abnormalities are believed to contribute to age-related infertility. Improvement of the mitochondrial function can lead to better fertility outcomes, and application of mitochondria replacement strategy or mitochondrial transfer to age-related infertility will be possible in the future. This review paper, we are trying to discuss current understanding about age-related changes in oocyte quality and mitochondrial dysfunction

Strategies of infertility treatment with human immature oocytes

Human immature oocytes can be matured in vitro following culture. In vitro maturation (IVM) refers to maturation in culture of immature oocytes at different stages that may or may not have been exposed to short courses of gonadotropins. The source of immature oocytes is an important feature for the subsequent embryonic development and pregnancy, as well healthy live births. IVM is an efficient treatment that has already achieved significant outcomes in terms of acceptable pregnancies and implantation rates and resulted in the births of several thousands of healthy babies. As the development of IVM treatment continues, an attractive possibility for improving the already successful outcome is to combine a natural cycle in vitro fertilization (IVF) treatment with an immature oocyte retrieval followed by IVM of those immature oocytes. If the treatment processes can be simplified with immature oocyte retrieval, different types of infertile women may be able to take advantage of these treatments. Although IVM treatment is still considered experimental by the society, it is time to reconsider the IVM technological evolution. Mild stimulation IVF combined with IVM treatment represents a viable alternative to the standard treatment, and as data accumulate over time, it may prove to be an optimal first-line treatment approach

In vitromaturation of human immature oocytes for fertility preservation

Cryopreservation of embryos, oocytes, or ovarian tissues is the main option for female fertility preservation. Oocyte cryopreservation has emerged as especially important: the dramatic increase in the number of infants born from vitrified oocytes indicates that it is becoming one of the most important intervention options. However, oocyte cryopreservation with standard controlled ovarian hyperstimulation may not be feasible for some cancer patients as there are serious concerns about the effect of ovarian stimulation with hormones on the risk of cancer recurrence. Also, urgent gonadotoxic cancer treatment may not allow sufficient time for a patient to undergo hormonal ovarian stimulation. Thus, immature oocyte retrieval from ovaries without ovarian stimulation followed by in vitro maturation and vitrification is a promising fertility preservation option for women who cannot undergo ovarian stimulation or cannot delay their gonadotoxic cancer treatment. Immature oocytes can be collected from the ovaries during both the follicular and luteal phases, which maximizes the possibility for fertility preservation. The combination of ovarian tissue cryopreservation with immature oocyte collection from the tissue followed by oocyte vitrification via in vitro maturation represents another promising approach of fertility preservation in young women with cancer. (Fertil Steril Ò 2013;-: ---

Comparison of pregnancy outcomes in natural cycle IVF/M treatment with or without mature oocytes retrieved at time of egg collection

The objective of this study is to compare the pregnancy and live birth rates of a natural cycle in vitro fertilization (IVF) combined with in vitro maturation (IVM) treatment (natural cycle IVF/M) by the presence or absence of mature oocytes retrieved. Infertile women were divided into two groups: (A) patients with mature oocytes found at retrieval and (B) patients with only immature oocytes at retrieval. Patients of group A were further divided into three subgroups: (A1) mature oocytes retrieved from both the leading and the small follicles, (A2) mature oocytes retrieved from the leading follicles only, and (A3) mature oocytes retrieved from the small follicles only. Pregnancy and implantation rates were compared. The results indicate that the clinical pregnancy rates were 40.1% (126/314) and 34.5% (19/55) for groups A and B, respectively. There were no differences in pregnancy rates among the subgroups: A1 = 44.0% (66/150), A2 = 34.9% (30/86), and A3 = 38.5% (30/78). In addition there were no differences in implantation rates among the groups (16.2% = 139/859, 15.0% = 22/147, 16.8% = 69/410, 14.7% = 34/232, and 16.6% = 36/217, respectively). However, the live birth and miscarriage rates were significantly different between the group A and group B (29.6% = 93/314 vs. 16.4% = 9/55 and 26.2% = 32/126 vs. 52.6% = 10/19, respectively). In conclusion, for natural cycle IVF/M treatment, although the clinical pregnancy rates are not different regarding the retrieval of mature oocytes or the time of the egg retrieval, the live birth rate is higher (P < 0.05) when the mature oocytes are obtained at the time of the egg retrieval