Impact of equilibration duration combined with temperature on the outcome of bovine oocyte vitrification
Garcia Martinez, Tania (Universitat Autònoma de Barcelona. Departament de Medicina i Cirurgia Animals)
Martínez-Rodero, Iris (Universitat Autònoma de Barcelona. Departament de Medicina i Cirurgia Animals)
Roncero-Carol, Joan (Universitat Autònoma de Barcelona. Departament de Medicina i Cirurgia Animals)
Yánez-Ortiz, Iván (Universitat Autònoma de Barcelona. Departament de Medicina i Cirurgia Animals)
Higgins, Adam Z (Oregon State University. School of Chemical, Biological and Environmental Engineering)
Mogas Amorós, Teresa (Universitat Autònoma de Barcelona. Departament de Medicina i Cirurgia Animals)

Data:	2022
Resum:	The cryopreservation of mammalian oocytes and embryos has become an integral part of assisted reproduction in both humans and veterinary species. However, the methods used to cryopreserve bovine oocytes still have significant shortcomings. A wide variety of approaches has been used to try to improve and optimize methods of cryopreservation. However, these procedures employed are not always designed to specifically take account of the osmotic tolerance response of the cells according to the temperature and time of cryoprotectant (CPA) addition. When these properties are considered, optimal procedures for the addition of CPAs can be designed proactively. Based on in silico and in vitro osmotic observations, we propose shorter dehydration-based protocols at different temperatures (25°C vs. 38. 5°C) towards defining an improved cryopreservation method. In vitro matured oocytes were exposed to equilibration solution (ES) at 25°C and 38. 5°C and effects of optimized exposure times for each temperature were determined prior to vitrification/warming on oocyte spindle configuration, DNA fragmentation, and further embryo development. Upon exposure to standard ES (7. 5% dimethyl sulfoxide + 7. 5% ethylene glycol in TCM199 medium + 20% fetal bovine serum), original oocyte volume was recovered within 2 min 30 s at 38. 5°C and 5 min 30 s at 25°C. In vitro matured oocytes were then exposed to the aforementioned cryoprotectants at both temperature/duration conditions and vitrified/warmed. While similar percentages of oocytes exhibiting a normally configured spindle and DNA fragmentation were observed in the fresh control group and oocytes vitrified at 38. 5°C, significantly higher apoptosis rate and lower percentages of normal spindle configuration were observed in oocytes vitrified at 25°C when compared to control fresh oocytes. Similar cleavage rates and blastocyst yields were observed in the vitrified/38. 5°C and fresh controls, while these rates were lower in vitrified/25°C. These results revealed that the limitation of the exposure time of the oocytes to the ES to the point of osmotic equilibrium volume recovery could be a more efficient approach to prepare them for vitrification. Therefore, exposure time to ES to 2 min 30 s at 38. 5 °C appears to improve the quality of vitrified/warmed oocytes by protecting spindle integrity and reducing DNA fragmentation thus improving blastocyst rates and embryo quality.
Ajuts:	Agència de Gestió d'Ajuts Universitaris i de Recerca 2017 SGR 1229 Ministerio de Ciencia e Innovación PID2020-116531RB-I00
Nota:	Altres ajuts: acords transformatius de la UAB
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Membrane permeability ; Osmotic behavio ; Meiotic spindle ; DNA fragmentation ; Embryo development
Publicat a:	Theriogenology, Vol. 184 (may 2022) , p. 110-123, ISSN 0093-691X

DOI: 10.1016/j.theriogenology.2022.02.024

14 p, 1.8 MB

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