Rapid cryopreservation of small quantities of human spermatozoa by a self-prepared cryoprotectant without animal component

Abstract

Cryopreservation of small quantities of human spermatozoa whilst maintaining adequate post-thawing motility has been found an essential challenge for male fertility preservation. Therefore, the study used an effective, and convenient rapid-freezing method to freeze small amounts of human spermatozoa by adding self-prepared cryoprotectant (SPC) without animal component. In the feasibility experiment, no significant differences in progressive motility, normal sperm morphology, vitality or DNA fragmentation index between the conventional slow freezing and rapid freezing were realised. The present study prospectively analysed the effects of sperm freezing and resuscitation in 175 patients with severe oligozoospermia (sperm concentration <1 × 106/ml). We observed the 120 severe oligozoospermia specimens had a mean recovery rate of 60.19% ± 10.43% and a mean cryosurvival rate of 68.0% ± 9.17%. In addition, 55 cryptozoospermia specimens were analysed. The small-volume cryopreservation showed advantages. The total sperm recovery, motility recovery and sperm loss rates were 98.48%, 50.17% and 1.52% respectively. In short, the SPC is safe and effective, and can be used to rapidly freeze severe oligozoospermia specimens. That is useful for successful sperm freezing whilst avoiding the risk of azoospermia in the later stages and promoting comprehensive fertility preservation.