Sperm cryostorage in a dry tank: An accurate alternative

Stéphanie Mestres (1) , Hanae Pons-Rejraji (1, 2) , Bruno Pereira (3) , Cyril Bouche (1) , Aurelie Vega (1) , Laure Chaput (1, 2) , Solène Vorilhon (1) , Laurent Janny (1) , Florence Brugnon (1, 2)

1 CHU Estaing [Clermont-Ferrand]
2 IMoST - Imagerie Moléculaire et Stratégies Théranostiques
3 CHU Clermont-Ferrand

This prospective study aimed to determine the effects of dry nitrogen cryostorage on human sperm characteristics in comparison with liquid nitrogen cryostorage. For this purpose, 42 men undergoing routine semen analysis (21 normozoospermia and 21 with altered semen parameters) were analyzed. After slow freezing, half of the straws of each sample were randomly stored in liquid and dry tanks, at the top and bottom levels of the latter. After 6 months storage, thawed samples were treated by density gradient centrifugation and sperm characteristics were compared. There was no difference in sperm progressive motility (15.1% ± 14.2% vs. 15.1% ± 12.7%; p = 0.76), sperm vitality (25.5% ± 17.7% vs. 26.2% ± 19%; p = 0.71), percentages of acrosome-reacted spermatozoa (38% ± 8.5% vs. 38.5% ± 7.4%; p = 0.53) and DNA fragmentation spermatozoa (27.3% ± 12.4% vs. 28.5% ± 12.9%, p = 0.47) after cryostorage in the dry or the liquid nitrogen tank. Moreover, we did not observe differences between either cryostorage system for normal and altered sperm samples. This lack of difference was also observed whatever the floor level of cryostorage in the dry tank. The temperature measurement of the dry tank showed a stable temperature at −194 °C throughout storage whatever the storage floor level, guaranteeing the stability of the low temperatures suitable for human sperm storage. Because of its greater safety, dry storage without contact with the liquid phase should be preferred and can be a useful alternative for the cryostorage of human sperm samples.

Mots clés: Cryostorage; Human sperm; Dry tank; Liquid nitrogen tank; Motility; Vitality; Acrosome integrity; DNA fragmentation

Domaines: Sciences du Vivant [q-bio]

Stéphanie Mestres, Hanae Pons-Rejraji, Bruno Pereira, Cyril Bouche, Aurelie Vega, et al.. Sperm cryostorage in a dry tank: An accurate alternative. Cryobiology, 2020, 94, pp.32-39. ⟨10.1016/j.cryobiol.2020.05.002⟩. ⟨hal-03045782⟩