Differential impact of four sperm preparation techniques on sperm motility, morphology, DNA fragmentation, acrosome status, oxidative stress and mitochondrial activity: a prospective study.

BACKGROUND Suboptimal human semen handling in vitro may induce sperm damage. However, the effects of semen swim-up (S-SU), pellet swim-up (P-SU), density gradient (DG) and DG followed by SU (DG/SU) on sperm motility, morphology, DNA fragmentation, acrosome reaction, intracellular reactive oxygen species (ROS) and mitochondrial activity were not fully understood. OBJECTIVES To study the impact of four sperm preparation techniques on sperm functional parameters MATERIALS AND METHODS: This study was conducted on 60 infertile men with a minimum sperm concentration of 20 x 106 /ml and total sperm motility of ≥ 30%. Each raw semen sample was divided into four aliquots. Each aliquot was prepared by one of the tested techniques. Various sperm characteristics were assessed before and after sperm preparation. RESULTS DG and DG/SU resulted in significantly higher DNA fragmentation percentages compared to S-SU (p<0.001 and p<0.001, respectively) and P-SU (p<0.001 and p<0.001, respectively). Significantly higher percentages of sperm with intact acrosome were detected in S-SU (p<0.001) and P-SU (p<0.001) compared to raw semen. The percentage of ROS positive spermatozoa was significantly higher after P-SU (p<0.001), DG (p<0.001) and DG/SU (p<0.001) than raw semen. In addition, the percentages of 100 % stained midpiece (active mitochondria) were significantly higher in S-SU (p<0.001) and P-SU (p<0.001) compared to raw semen. DISCUSSION AND CONCLUSION To the best of our knowledge, this is the first report comparing the impact of these techniques on various sperm functional parameters. S-SU was more effective than DG in selecting better spermatozoa in terms of DNA integrity, ROS levels, acrosome status and mitochondrial activity. Randomized clinical trials comparing these four techniques are required to test their impact on embryo development and pregnancy outcomes.