Double-in vitro maturation increases the number of vitrified oocytes available for fertility preservation when ovarian stimulation is unfeasible

In vitro maturation (IVM) of human immature oocytes: is it still relevant?

In vitro maturation (IVM) of human immature oocytes has been shown to be a viable option for patients at risk of ovarian hyperstimulation syndrome (OHSS), those seeking urgent fertility preservation and in circumstances where controlled ovarian stimulation is not feasible. Moreover, IVM techniques can be combined with ovarian tissue cryobanking to increase the chances of conception in cancer survivors. The clinical applications of IVM in the field of reproductive medicine are rapidly expanding and the technique is now classified as non-experimental. In contrast to conventional IVF (in vitro fertilization), IVM offers several advantages, such as reduced gonadotropin stimulation, minimal risk of ovarian hyperstimulation syndrome (OHSS), reduced treatment times and lower costs. However, the technical expertise involved in performing IVM and its lower success rates compared to traditional IVF cycles, still pose significant challenges. Despite recent advances, such as innovative biphasic IVM systems, IVM is still an evolving technique and research is ongoing to refine protocols and identify techniques to improve its efficiency and effectiveness. A comprehensive understanding of the distinct mechanisms of oocyte maturation is crucial for obtaining more viable oocytes through in vitro methods, which will in turn lead to significantly improved success rates. In this review, the present state of human IVM programs and future research directions will be discussed, aiming to promote a better understanding of IVM and identify potential strategies to improve the overall efficiency and success rates of IVM programs, which will in turn lead to better clinical outcomes.

Twenty-first century oocyte cryopreservation—in vitro maturation of immature oocytes from ovarian tissue cryopreservation in cancer patients: A systematic review

Objectives:

Our review aimed to consolidate the latest update on the application of in vitro maturation among immature oocyte harvest in combination with ovarian tissue cryopreservation known as ovarian tissue oocyte–in vitro maturation.

Methods:

A thorough search for relevant studies was conducted via PubMed, Google Scholar, EMBASE, and clinical.gov databases up to December 2020. The primary outcome was the oocyte maturation rate, which measured the number of immature oocytes (geminal vesicle stage) that progressed to mature oocytes (meiosis II stage) following in vitro maturation. The secondary outcomes were the fertilization rate following intracytoplasmic sperm injection/in vitro fertilization of these oocytes for the embryo cryopreservation cohort. Our review included pre-pubertal girls and women with cancer who underwent ovarian tissue oocyte–in vitro maturation as fertility preservation.

Results:

The primary search identified 207 studies. Twelve manuscripts were selected for inclusion in our review following duplication assessment, title and abstract screening, and full-text evaluation tailored to our inclusion criteria. All the population belonged to a cancer group and underwent concurrent ovarian tissue oocyte–in vitro maturation. A total of 5724 immature oocytes were obtained following ovarian tissue cryopreservation. Approximately 33.84% of the immature oocytes successfully matured via in vitro maturation, which were cryopreserved as oocytes or fertilized as embryos and subsequently stored for future use.

Conclusion:

Our review proposed the potential application of ovarian tissue oocyte–in vitro maturation in increasing the number of mature oocytes. The acceptable improvement in oocyte maturation rate following in vitro maturation indicates that improving oocyte outcomes is an excellent cost-effective strategy for fertility preservation among women with cancer.

Perspectives on the development and future of oocyte IVM in clinical practice

Oocyte in vitro maturation (IVM) is an assisted reproductive technology designed to obtain mature oocytes following culture of immature cumulus–oocyte complexes collected from antral follicles. Although IVM has been practiced for decades and is no longer considered experimental, the uptake of IVM in clinical practice is currently limited. The purpose of this review is to ensure reproductive medicine professionals understand the appropriate use of IVM drawn from the best available evidence supporting its clinical potential and safety in selected patient groups. This group of scientists and fertility specialists, with expertise in IVM in the ART laboratory and/or clinic, explore here the development of IVM towards acquisition of a non-experimental status and, in addition, critically appraise the current and future role of IVM in human ART.