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Closed vitrification of mouse oocytes using the CryoLogic vitrification method: A modification that improves
Jun Woo Jo1, Byung Chul Jee2, Chang Suk Suh2
1Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea. ; Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea. ; Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University, Seoul, Korea.
The modified CryoLogic vitrification method (CVM) shows promise as an alternative to open vitrification for mouse oocytes, offering comparable developmental outcomes. Further research is needed to reduce apoptosis in blastocysts.
Area of Science:
- Reproductive Biology
- Cryopreservation
- Oocyte Vitrification
Background:
- Oocyte cryopreservation is crucial for assisted reproductive technologies and genetic resource preservation.
- Vitrification, a rapid cooling method, is preferred for oocytes due to reduced ice crystal formation.
- Conventional open-pull-pull and Cryotop methods are widely used but carry risks of contamination.
Purpose of the Study:
- To compare the efficacy of the CryoLogic vitrification method (CVM) against the conventional open Cryotop method for mouse oocyte vitrification.
- To evaluate two variations of the CVM: the original CVM and a modified CVM protocol.
Main Methods:
- Mature mouse oocytes were vitrified using a two-step solution exposure protocol.
- Three groups were tested: original CVM, modified CVM, and Cryotop (open method).
- Post-warming assessment included in vitro fertilization, embryo development, blastomere apoptosis, spindle morphology, and chromosome configuration.
Main Results:
- The modified CVM and Cryotop groups demonstrated comparable oocyte developmental capacity and structural integrity (spindle and chromosome).
- The modified CVM protocol significantly outperformed the original CVM in developmental competence and spindle preservation.
- A higher incidence of apoptotic cells was observed in blastocysts derived from the CVM group compared to the Cryotop group.
Conclusions:
- Closed vitrification using the modified CVM protocol is a viable alternative to the conventional open Cryotop method for mouse oocytes.
- Strategies to mitigate blastomere apoptosis in CVM-vitrified oocytes require further investigation.
- The modified CVM offers potential benefits in terms of reduced contamination risk associated with open methods.
