Shearing forces during sperm preparation for assisted reproduction techniques may lead to excessive production of reactive oxygen species (ROS) which may have an unpleasant effect on embryonic development. In the current study, we assessed the effect of alpha‐lipoic acid (ALA) on ROS‐induced damages during sperm preparation process. Semen samples were collected from 15 normozoospermic men. Each semen sample was divided into two parts; one part was washed and centrifuged with sperm washing medium plus 0.02 mM ALA. Then, sperm pellet was diluted and incubated for 1 hr at 37°C in sperm washing media in the absence (ALA−) or presence of 0.02 mM ALA (ALA+). The second part was washed and centrifuged with sperm washing media in the absence of ALA, and then, sperm pellet was incubated for 1 hr at 37°C in sperm washing media in the absence (ALA−) or presence of 0.02 mM ALA (ALA+). Sperm viability, motility, intracellular oxidative stress and DNA fragmentation were assessed by eosin‐nigrosin, computer‐assisted sperm analysis system, H2DCFDA staining and acridine orange staining respectively. Our results showed that addition of ALA as a fat‐ and water‐soluble antioxidant to sperm washing media maintains sperm viability and motility by reduction in ROS production and can also protect sperm DNA integrity.

The reduction of sperm motility and subsequently reduced ability to undergo capacitation and acrosome reaction are considered as common causes of male infertility. The β‐defensin family is a group of well‐known secretory proteins with antimicrobial activity that contribute to the process of “sperm maturation” during the passage of spermatozoa in the epididymis when spermatozoa attain its motility. One member of this family is “β‐defensin 1” which is present in seminal plasma and spermatozoa. The aim of this study was the incubation of human processed spermatozoa with recombinant β‐defensin 1 (500 ng/ml) for 1, 2 and 3 hr at 37°C under 5% CO2 atmosphere and assessment of sperm viability and motility in 59 semen samples. The analysis of semen samples such as sperm concentration, motility, viability, morphology and semen volume was performed according to the World Health Organization (2010; World health organization laboratory manual for the examination and processing of human semen (p. 287). Geneva, Switzerland: World Health Organization) criteria. The result of the current study shows that the incubation of spermatozoa with recombinant β‐defensin significantly maintained percentage of sperm viability and motility compared to processed spermatozoa incubate in the absence of β‐defensin in the studied time intervals (p < .05). Therefore, we concluded that recombinant β‐defensin 1 protein as an agent with antimicrobial activity can maintain sperm viability and motility in in vitro condition.

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