Sperm Oxidative Stress during In Vitro Manipulation and Its Effects on Sperm Function and Embryo Development

Abstract

Reactive oxygen species (ROS) generated at low levels during mitochondrial respiration have key roles in several signaling pathways. Oxidative stress (OS) arises when the generation of ROS exceeds the cell’s antioxidant scavenging ability and leads to cell damage. Physiological ROS production in spermatozoa regulates essential functional characteristics such as motility, capacitation, acrosome reaction, hyperactivation, and sperm-oocyte fusion. OS can have detrimental effects on sperm function through lipid peroxidation, protein damage, and DNA strand breakage, which can eventually affect the fertility of an individual. Substantial evidence in the literature indicates that spermatozoa experiencing OS during in vitro manipulation procedures in human- and animal-assisted reproduction are increasingly associated with iatrogenic ROS production and eventual impairment of sperm function. Although a direct association between sperm OS and human assisted reproductive techniques (ART) outcomes after in vitro fertilization (IVF) and/or intracytoplasmic sperm injection (ICSI) is still a matter of debate, studies in animal models provide enough evidence on the adverse effects of sperm OS in vitro and defective fertilization and embryo development. This review summarized the literature on sperm OS in vitro, its effects on functional ability and embryo development, and the approaches that have been proposed to reduce iatrogenic sperm damage and altered embryonic development.

Supplementation of Mito TEMPO and acetovanillone in semen extender improves freezability of buffalo spermatozoa

“…Significantly lower MDA production was also observed in acetovanillone supplemented (50 μM) group than the control group, which might be because of targeted minimization of ROS production at the plasma membrane level. Relatively greater membrane intact and progressive motile spermatozoa in this group might have contributed to more MDA production than other treatment groups because of a procedural time lag in LPO estimation 70 …”

Oxidative Stress and Assisted Reproduction: A Comprehensive Review of Its Pathophysiological Role and Strategies for Optimizing Embryo Culture Environment

“…In an ART setting, gametes undergo in vitro manipulation, which inevitably expose these cells to OS [51]. This is particularly true in sperm that have a limited amount of intracellular AOXs [52].…”

“…This is particularly true in sperm that have a limited amount of intracellular AOXs [52]. During sperm preparation for ART, semen samples are usually washed, and the seminal plasma removed [51]. Seminal plasma physiologically provides AOX protection, as it contains a wide range of both enzymatic [e.g., superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), etc.]…”

“…compounds with antioxidant properties [52]. In addition, during swim-up, sperm may come in close contact with leukocytes and immature germ cells (both of which represent major sources of ROS) before migrating to the surface [51]. Furthermore, the centrifugation steps of sperm preparation techniques further result in increased ROS generation [52], with longer centrifugation time being associated with higher amounts of ROS and sperm damage [53].…”

The Sixth Edition of the WHO Manual for Human Semen Analysis: A Critical Review and SWOT Analysis

“…Due to the production of excessive amounts of ROS in numerous medical conditions, including varicocele [43], leukocytospermia [44], diabetes mellitus [45], and obesity [46], seminal OS develops. Consequently, OS negatively affects all sperm functions, including sperm DNA integrity [47,48], and thereby the fertilization process and reproductive outcomes [49][50][51][52][53][54][55].…”