Vitrification of human spermatozoa : the effects of antioxidant supplementation on post-warmed sperm parameters

Abstract

Human sperm cryopreservation provides an option to male patients who wish to retain fertility for medical or personal reasons. Though the development of this technique benefits patients in need, some technical issues related to oxidative damages remain unresolved. Excessive reactive oxygen species (ROS) induced by cryopreservation can exceed the endogenous antioxidant capacity resulting in oxidative stress. The vulnerability of spermatozoa to oxidative damages can result in severe impairment of sperm parameters. The hypothesis of this study was that the supplementation of vitrification medium with exogenous antioxidants protect human spermatozoa against oxidative damages and subsequently improve the post-warmed parameters. The first objective was to evaluate the effects of vitamin E, spermine, vitamin C and lycopene on the pre-vitrified spermatozoa; and identify the optimal concentrations of each treatment group prior to vitrification. The treatment groups of vitamin C at 25, 50, 100 μM, vitamin E at 250, 500, 1000 μM, spermine at 125, 250, 500 μM and lycopene at 1.5, 3.0, 6.0 μM demonstrated no adverse effects on the sperm parameters in terms of motility, viability and capability to undergo acrosome reaction induced by calcium ionophore A23187. The preliminary data of this study demonstrated the detrimental impacts of cryopreservation on post-warmed sperm parameters. The comparison between the pre-vitrified and post-warmed parameters revealed that cryopreservation reduced the post-warmed progressive motility by more than 80% compared to the control. The second objective was to examine whether supplementation of the vitrification medium with vitamin E, spermine, vitamin C and lycopene could improve the post-warmed sperm parameters in terms of motility, viability, capability to undergo acrosome reaction induced by calcium ionophore A23187 and DNA fragmentation. In conclusion, the results of this study validated the protective effects of exogenous antioxidants on human spermatozoa. Vitamin C and spermine respectively improved the post-warmed parameters in terms of progressive motility, viability, acrosomal integrity and DNA fragmentation of vitrified spermatozoa. The use of these antioxidants could potentially protect human spermatozoa against oxidative damages induced by cryopreservation and subsequently improve the fertilizing ability.