Problems of human spermatozoa cryopreservation: research methods, solutions

Cryopreservation of male gametes is one of the most important methods of assisted reproductive technologies, which allows preserving gametes for research or further use. However, the fertilizing ability of spermatozoa after cryopreservation decreases by 30-70%, which makes it urgent to search for new substances with cryoprotective properties. The review considers the main causes of cell damage during cryopreservation. The relevance of methods for assessing the formation of crystals and the physicochemical properties of cryoprotective media depending on various compositions is discussed. The problem of stabilization of the spermatozoa membrane during cryopreservation is considered. A possible solution to the problem of membrane integrity may consist in modification of the basic cryoprotective media with yolk emulsion or development of methods for saturation of the membrane phospholipid layer with cholesterol.

Apple Pectin as a New Component for Cryopreservation of Nucleated Cells

This study explored the ability of apple pectin AU-701 to change the freezing point of water in cryoprotectant solutions with different penetrating abilities using glycerol, dimethyl sulfoxide (DMSO), 1,2-propanediol (1,2-PD), dimethyl acetamide (DMAC), hydroxyethyl starch (HES), hexamethylenebistetraoxyethylurea (or substance A-378), and in biological fluid (human venous blood). An effective interaction was used to protect human blood leukocytes at ultrafreezer temperature (-80°C). Apple pectin affects the freezing temperature of water in different ways and it depends on the medium in which it is dissolved, as it either slows down the freezing process (in glycerol) or accelerates it (venous blood). The addition of apple pectin to the cryosolution increases the activity of the base cryoprotector (glycerol) even at low concentrations. Therefore, the combination of these substances can be effective in freezing biological substances, which is proved by indicators of safety of leukocytes during the freezing process at low temperature (-80°C) for 14 days.