Selection of non-apoptotic, DNA intact spermatozoa: an approach to improve sperm fertilization potential

The impact of seminal reactive oxygen species (ROS), sperm DNA damage and apoptosis on male infertility remains to be fully elucidated. There appears to be a need to develop new sperm preparation techniques that consider these molecular pathways and subsequently may improve outcomes of assisted reproductive techniques (ART). The specific aims of our research were to: 1) examine the role of some sperm morphological attributes in the occurrence of ROS-mediated DNA damage; 2) test the hypothesis of using the magnetic activated cell sorting (MACS) as a sperm preparation method that excludes apoptotic sperm; 3) examine the extent of improvement in sperm parameters following MACS; and 4) identify the MACS protocol limitations and which ART procedures would benefit the most from its application. Based on our findings, we conclude that: 1) a rise in sperm DNA damage should be expected in conjunction with immature spermatozoa due to NADPH-mediated increase in ROS; 2) MACS could be considered as a feasible sorting system for the separation of non-apoptotic spermatozoa; 3) the implementation of MACS yields a sperm population characterized by higher motility, viability, more normal morphology and reduced DNA fragmentation; and 4) separated non-apoptotic spermatozoa display higher tolerance to cryopreservation and potentially better fertilization capacity as documented by higher hamster oocyte penetration. Thus, the use of MACS may significantly enhance the outcome of intrauterine insemination or in vitro fertilization where the sperm DNA integrity is expected to play a significant role in determining success rates.