Addition of Tempol in semen cryopreservation medium improves the post-thaw sperm function.

Despite extensive research carried out for optimization and commercialization of sperm cryopreservation media, percentage of motility and viability remain low following cryopreservation. These adverse effects have been partially ascribed to reactive oxygen species (ROS) production during cryopreservation. Therefore, we proposed that addition of a cell permeable antioxidant like Tempol, with superoxide dismutase (SOD) mimetic action, may overcome these effects in an optimized commercially available cryo-protective medium. Therefore, semen samples were cryopreserved in the presence or absence of Tempol. A concentration of 5 μM Tempol was defined as optimal since it significantly improved motility and viability post thawing and reduced DNA fragmented sperm. In addition, percentage of ROS positive sperm was reduced. These effects of Tempol can be attributed to cell permeability characteristic and ability to reduce superoxide production both at intra- and extra-cellular levels. Tempol may hold the potential for clinical applications.