Utility of sperm DNA fragmentation testing in different clinical scenarios of male reproductive abnormalities and its influence in natural and assisted reproduction

tau.amegroups.com © Translational Andrology and Urology. All rights reserved. One of the measurements of sperm quality that can be assessed with validated protocols is DNA fragmentation, the subject was profoundly dissected in the article by Agarwal et al. and that constitutes the backbone of this commentary (1). Authors quoted: “Over the past decade, Sperm DNA Fragmentation (SDF) measurements have been extensively investigated and correlated with various disease entities. While SDF is increasingly being available in the urologists’ armamentarium for the evaluation of infertile men, its accurate clinical implication is still poorly understood. Few metaanalyses have been made withdrawing valuable conclusions on the significance of SDF in various contexts of male infertility, yet a precise understanding of the specific utility of such test in different clinical scenarios is still lacking.” The abnormal sperm nuclear condensation process involves a complex sequence of events including topological rearrangements, transition of DNAbinding proteins, transcriptional alterations, nucleosomal structure loss and abnormal condensation of chromatin resulting in disturbances in the organization of genomic material in the sperm nuclei and decreasing sperm functional ability. Ultimately this reduces normal fertilization, affects early embryonic development and interferes with the primary mission of the sperm DNA which is reliable transmission of paternal genetic information (2-4). The end-result of these abnormalities is translated into the SDF test. A higher SDF level is found in men with abnormal semen parameters and normozoospermic partners of infertile couples, and the mechanism in SDF analysis relies in oxidative stress induced DNA damage during migration of mature sperm with reactive oxygen species (ROS) producing immature and defective sperm through the epididymis and seminal tract (5). This is the rationale behind all SDF tests described in the article by Agarwal et al. who described that there are two types of assays that have been developed to measure SDF: those that can directly measure the extent of DNA fragmentation using probes and dyes and those that measure the susceptibility of DNA to denaturation, which occurs more commonly in fragmented DNA. They described eight standardized methods, although the most used tests are terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), the COMET assay, the sperm chromatin dispersion (SCD) test, and the sperm chromatin structure assay (SCSA), we will focus on these four for this discussion, as they are the most reliable and reproducible among the eight and as we are trying to add a reliable step into the laboratory evaluation of the infertile male and, of course reliability and ease of reproducibility are fundamental pre-requisites. SCSA (6) is the flow cytometric measurement of the susceptibility of sperm DNA to acid-induced denaturation after staining with acridine orange, a fluorescent dye. The use of a flow cytometer allows that 5,000 to 10,000 sperm cells can be evaluated in a few seconds and thus Commentary