Cryopreservation is a modern convenient method of storing biological material. However, cryopreservation can also lead to undesirable effects caused by damage of biological material. To protect cells from damage, cryoprotective media are used, including components penetrating into the cell (glycerin, DMSO) and non-penetrating (disaccharides, proteins). Egg Yolk is a non-penetrating component. Earlier in our work, it was shown that the modification of cryoprotectants with egg yolk suspension is one of the most effective methods for improving the survival of spermatozoa. However using compounds that are received from the animal for storing human cells is difficult. In this work the protocol of preparation of an egg yolk components: lecithin and cholesterol and the scheme of basic cryoprotectant SpermFreeze modification are suggested. Cytotoxicity tests have been done for various cholesterol solvents, the concentrations of all components were selected, changes in the sperm motility index after freezing and thawing were determined in all studied modifications of the cryoprotective medium. In this paper methods for measuring cholesterol concentration in sperm membranes were compared to select the optimal protocol. It has been also shown that modification of the base cryoprotectant with cyclodextrin-cholesterol complexes increases the survival rate of spermatozoa by 13% and is effective as with the addition of a suspension of egg yolk; the addition of lecithin does not significantly increase the effectiveness of the base cryoprotector.
cryoprotectant, egg yolk, lecithin, cholesterol, sperm motility, ART
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