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Fertility Preservation Through Oocyte Vitrification: Clinical and Laboratory Perspectives
Published on: September 16, 2021
Oocyte cryopreservation: oocyte assessment and strategies for improving survival
Sergio Ledda1, Luisa Bogliolo, Sara Succu
1Department of Animal Biology, Veterinary Faculty, University of Sassari, 07100 Sassari, Italy. giodi@uniss.it
Abstract:
Despite significant progress in cryopreservation of mammalian oocytes and embryos, many ofthe molecular and biochemical events that underlie this technology are poorly understood. In recent years, researchers have focused on obtaining viable oocytes that are developmentally competent. Even under the most favourable conditions, experimental approaches have achieved only limited success compared with fresh oocytes used in routine in vitro embryo production. Chilling injuries and toxic effects of the cryoprotectants are the major adverse consequences following cryoprocedures. To overcome these problems, different strategies have been developed for improving cryopreservation results. These strategies include reducing container volumes, increasing the thermal gradient, changing the cell surface/volume ratio, enhancing cryotolerance by supplementation with various additives or modifying the lipid composition of the oocyte membrane. In order to develop new strategies for reducing the various forms of stress associated with oocyte cryopreservation, it is fundamental to gain a better understanding of the major changes responsible for poor post-thaw survival. With this knowledge, we hope that oocyte cryostorage will become a fully reliable reproductive technique in the near future.
Insights
Cryopreservation of mammalian oocytes faces challenges due to chilling injury and cryoprotectant toxicity, limiting developmental competence. Understanding these molecular events is key to improving cryostorage viability for assisted reproduction.
Area of Science:
- Reproductive Biology
- Cryobiology
- Developmental Biology
Background:
- Mammalian oocyte cryopreservation shows progress but lacks full understanding of underlying molecular and biochemical events.
- Current methods achieve limited success compared to fresh oocytes, hindering routine in vitro embryo production.
- Chilling injury and cryoprotectant toxicity are primary causes of poor post-thaw oocyte survival and developmental competence.
Purpose of the Study:
- To investigate the molecular and biochemical mechanisms behind poor post-thaw survival in cryopreserved mammalian oocytes.
- To identify key changes responsible for reduced viability and developmental competence after cryopreservation.
- To inform the development of novel strategies for improving oocyte cryopreservation outcomes.
Main Methods:
- Review and synthesis of existing research on oocyte cryopreservation challenges and strategies.
- Analysis of factors contributing to chilling injury and cryoprotectant toxicity.
- Exploration of techniques to mitigate cryodamage, including container volume, thermal gradients, cell surface/volume ratio, additives, and lipid modification.
Main Results:
- Significant knowledge gaps exist regarding the molecular basis of oocyte cryoinjury.
- Strategies like reduced container volumes and modified lipid composition show potential for enhancing cryotolerance.
- Understanding stress factors is crucial for developing effective cryopreservation protocols.
Conclusions:
- A deeper understanding of molecular and biochemical changes during cryopreservation is fundamental for improving oocyte viability.
- Developing new strategies to reduce cryodamage is essential for reliable oocyte cryostorage.
- Advancements in oocyte cryopreservation could significantly enhance assisted reproductive technologies.
