Sperm DNA integrity: a special issue exploring the causes, consequences, and treatment of DNA damage in human spermatozoa

Abstract

Since the pioneering studies by Don Evenson and colleagues first opened our eyes to the existence of DNA damage in subpopulations of human spermatozoa, 1 important questions have been raised concerning the causes, clinical significance, and resolution of this phenomenon. 2 In this Special Issue of Andrology, we have brought together a collection of cutting-edge research articles and reviews, reflecting the most recent advances in this area. We hope that this collection of articles will help andrologists recognize the importance of DNA damage in spermatozoa, understand where the knowledge gaps are, and thoughtfully engage in research designed to enhance our capacity to diagnose and manage this critical element of semen quality. OXIDATIVE STRESS AND SPERM DNA DAMAGEIn terms of the etiology of DNA damage, there appears to be a general consensus that oxidative stress makes a major contribution to its induction. 2 As highlighted in this Special Issue, we are beginning to gather a detailed understanding as to why oxidative stress is so important in the causation of sperm DNA damage, as well as the key role that enzymes such as topoisomerase might play in this process. 2 However, the source of the oxidative stress driving this DNA damage has remained largely unresolved. A complication in this regard is that every semen sample is contaminated with leukocytes, particularly neutrophils, and these cells are many times more active in generat-

Decrease in Sperm Parameters in the 21st Century: Obesity, Lifestyle, or Environmental Factors? An Updated Narrative Review

“…Recent investigations seem to indicate that the main testicular harm might be correlated to increased production of ROS and OS (Figure 3), leading to changes in protein conformation and induction of DNA damage [154][155][156][157]. Increased OS is a condition in which the natural balance between oxidants and antioxidants is disturbed; thus, free radicals are produced containing an uneven number of electrons, which react with other molecules to cause a series of chemical reactions that might be toxic to cells, tissues, and organs, including gametes and embryos [155][156][157][158].…”

“…Recent investigations seem to indicate that the main testicular harm might be correlated to increased production of ROS and OS (Figure 3), leading to changes in protein conformation and induction of DNA damage [154][155][156][157]. Increased OS is a condition in which the natural balance between oxidants and antioxidants is disturbed; thus, free radicals are produced containing an uneven number of electrons, which react with other molecules to cause a series of chemical reactions that might be toxic to cells, tissues, and organs, including gametes and embryos [155][156][157][158]. The effects caused by mobile phones are associated with increased production of seminal ROS and reduction in antioxidant enzymes, chromosomal abnormalities, micronuclei formation, and changes in the sperm membrane potential, as well as increased apoptosis and DNA fragmentation [158][159][160][161][162][163].…”