Impact of warming of vitrified semen at different temperatures on cryosurvival

Abstract

Background: Vitrification is an ultra-rapid cryopreservation method in which cells are directly exposed to liquid nitrogen (LN2). The warming protocol for vitrification is equally important as the freezing protocol because sperm damage can occur during the warming of sample as well. The warming rate is influenced by the warming medium (air, water) and temperature. A fast warming rate causes unbalanced glycerol efflux and water influx; however, a slow warming rate causes recrystallization of intracellular water microcrystals and leads to subcellular organelles damage. Aim: To determine the optimum devitrification temperature for vitrified human sperm by comparing prefreeze and postwarm motility parameters at different temperatures. Setting and Design: The prospective study was conducted on 100 patient semen samples. Materials and Methods: The semen sample was direct plunged into LN2 and warmed at different temperatures, that is, at room temperature (RT), 37°C and 42°C for 5 minutes. Sperm parameters were evaluated by the computer-assisted semen analyzer system. Statistical analysis was carried out by applying one-way analysis of variance was carried out using SPSS-22. The level of significance was taken as P ≤ 0.05. Results: The statistical significant difference was found in the case of recovery of all semen parameters, that is, motility (P < 0.0001), progressive motility (P < 0.0001), cryosurvival factor (P < 0.0001), curvilinear velocity (P = 0.049), straight-line velocity (P = 0.033), average path velocity (P = 0.0001), and except count (P = 0.083) between the RT, 37°C, and at 42°C. The cryosurvival factor of vitrified semen sample at RT, 37°C, and at 42°C was found to be 25.63 ± 13.885, 29.97 ± 13.212, and 41.99 ± 12.630, respectively. Hence, at 42°C, it was found to be maximum. Conclusion: The cryopreservation of the semen leads to a detrimental effect on spermatozoa. The basal semen parameters such as sperm motility, progressive motility, cryosurvival factor, and velocity parameters were affected by devitrification temperature. There was significantly high-sperm cryosurvival after warming of semen samples at 42°C when compared with warming at 37°C and RT. But velocity parameters were found to be better at 37°C.