Biopolymer gels as components of protective medium for cryopreservation of spermatogonial stem cells.

Biopolymer gels attract a lot of attention in a field of biothechnology due to their excellent compatibility and degradation. Their application is also promising for cryopreservation of spermatogonial stem cells (SSCs) which is so necessary to preserve the fertility of young patients. The aim of the study was to determine the effectiveness of biopolymer gels as a component of cryopreservation medium for SSCs of immature rats at the stage of exposure to cryoprotectants. It was found that 30-min exposure to cryopreservation media based on collagen or fibrin gel with an addition of 5% MeSO or 6% glycerol did not lead to significant changes in membrane integrity, cytochrome C content, metabolic, mitochondrial and antioxidant activities in SSCs compared to the control (Leibovitz-based cryomedium). But fibrin gel more than collagen reduced the toxic effects of MeSO and glycerol on SSCs increasing exposure time up to 45 min without significant changes in cell viability. The same cryoprotectants in Leibovitz-based media showed significant toxicity starting from the 15th minute of exposure. Necrosis was the main cause of cell death at this stage of cryopreservation in all experimental groups. The obtained results can be used to optimize SSC cryopreservation protocols for further cell autotransplantation for spermatogenesis initiation in boys who undergo gonadotoxic therapy in prepubertal age.