Antioxidants in Sperm Cryopreservation

Abstract

Cryopreservation and thawing expose spermatozoa to various stresses that could lead eventually to loss of fertilizing potential. Despite various advances in cryopreservation methodology, the recovery rate of functional post-thaw spermatozoa remains to be improved. The use of cryoprotectants such as glycerol, ethylene glycol, dimethyl sulfoxide (DMSO), and 1, 2-propanediol (PROH) marked one of the most significant advancements in cryopreservation. Cryoprotectants are low-molecular-weight, highly permeable chemicals that serve to protect spermatozoa from freeze damage induced by ice crystallization. Cryoprotectants act by decreasing the freezing point of a substance, reducing the amount of salts and solutes present in the liquid phase of the sample, and decreasing ice formation within the spermatozoa. Oxidative stress (OS), resulting from an imbalance between reactive oxygen species (ROS) and antioxidants, is detrimental to human spermatozoa resulting in significant loss of function. Increased ROS production and decreased antioxidant levels are known to occur during sperm cryopreservation and thawing. Therefore, OS does play a role in injury sustained by spermatozoa during cryopreservation. Subsequently, antioxidants which counteract the effects of ROS could be of use in preventing OS-induced cryoinjury.