Oxidative stress level in fresh ejaculate is not related to semen parameters or to pregnancy rates in cycles with donor oocytes

MiOXSYS® and OxiSperm® II assays appear to provide no clinical utility for determining oxidative stress in human sperm-results from repeated semen collections

BACKGROUND

Oxidative stress in semen contributes up to 80% of all infertility diagnosis. Diagnostics to measure oxidative stress in semen was recently added to the 6th edition WHO methods manual, although diagnostic predictive values need to be interpreted with caution as there are still several research questions yet to be answered.

OBJECTIVES

To determine the natural fluctuations in semen redox indicators (MiOXSYS® and OxiSperm® II) within and between men and their association with markers of sperm oxidative stress.

MATERIALS AND METHODS

Total, 118 repeat semen samples from 31 generally healthy men aged 18-45 years, over 6 months. Standard semen analysis as per 5th WHO manual. Semen redox levels measured via MiOXSYS® and OxiSperm® II. Additional attributes of sperm quality; HBA® binding assay and sperm hyperactivation and oxidative stress; DNA fragmentation (Halo® Sperm) and lipid peroxidation (BODIPY™ 581/591 C11) were assessed.

RESULTS

Samples with high redox-potential (MiOXSYS® ≥1.47 sORP/106 sperm/ml) had lower sperm, motility, morphology and higher DNA fragmentation (P < 0.05). Upon further analysis, these associations were driven solely by the adjustment of sperm concentration (106 /ml) in normalised redox-potential. No significant associations between NBT-reactivity (OxiSperm® II) and measures of the sperm function or oxidative stress were observed (P > 0.05). Fluctuations in semen redox levels varied greater between men than within men over the study period.

DISCUSSION

Neither MiOXSYS® nor OxiSperm® II assays were predictive of sperm function or sperm oxidative stress. This was likely due at least in part to limited understanding of their biochemistry and clinical application. As a result, these assays seem to provide no additional clinical utility beyond that of a standard semen analysis, highlighting the imperative for the development of new robust point-of-care devices for accurately determining sperm oxidative stress.

CONCLUSION

These findings suggest that MiOXSYS® and OxiSperm® II systems for the measurement of sperm oxidative stress may have limited diagnostic potential.

Measuring Reactive Oxygen Species in Semen for Male Preconception Care: A Scientist Perspective

Oxidative stress and elevated levels of seminal and sperm reactive oxygen species (ROS) may contribute to up to 80% of male infertility diagnosis, with sperm ROS concentrations at fertilization important in the development of a healthy fetus and child. The evaluation of ROS in semen seems promising as a potential diagnostic tool for male infertility and male preconception care with a number of clinically available tests on the market (MiOXSYS, luminol chemiluminescence and OxiSperm). While some of these tests show promise for clinical use, discrepancies in documented decision limits and lack of cohort studies/clinical trials assessing their benefits on fertilization rates, embryo development, pregnancy and live birth rates limit their current clinical utility. In this review, we provide an update on the current techniques used for analyzing semen ROS concentrations clinically, the potential to use of ROS research tools for improving clinical ROS detection in sperm and describe why we believe we are likely still a long way away before semen ROS concentrations might become a mainstream preconception diagnostic test in men.

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

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.

Differences between first and second ejaculations regarding seminal plasma calcium, magnesium and total antioxidant capacity in dual-purpose Fleckvieh bulls and their relationships with semen quality

Artificial insemination is a well-established and widely used method for genetic improvement in cattle breeding industry. Recently, researchers have shown an increased interest in the cryoprotective effects of minerals and antioxidants on semen. Previous studies on calcium (Ca) and magnesium (Mg), two main macro-minerals, have mainly investigated their roles in mammalian spermatogenesis and fertility. In addition, the experimental data examining the semen content regarding these minerals and antioxidants from different animal species are rather controversial and there is no general agreement about their associations with semen quality. Therefore, this study was conducted to assess the seminal plasma concentrations of Ca, Mg and total antioxidant capacity (TAC) in first and second ejaculations of dual-purpose Fleckvieh bulls and to link them to the sperm characteristics of fresh and frozen-thawed semen. Sperm progressive motility after thawing was used to classify the data into three groups: < 40.00%, 40.00 to 50.00% and > 50.00%. The measurements of two minerals and TAC were carried out using spectrophotometry and enzyme-linked immunosorbent assays, respectively. The results showed that there were significant differences in several parameters of semen quality between first and second ejaculations. No significant differences were also found on Ca and Mg concentrations and Ca/Mg ratio. The TAC level was significantly higher in the first ejaculation than the second one. The findings of this study suggest that TAC is a potential marker for bull semen quality assessment in the frozen semen production industry.

From Past to Present: The Link Between Reactive Oxygen Species in Sperm and Male Infertility

Reactive oxygen species (ROS) can be generated in mammalian cells via both enzymatic and non-enzymatic mechanisms. In sperm cells, while ROS may function as signalling molecules for some physiological pathways, the oxidative stress arising from the ubiquitous production of these compounds has been implicated in the pathogenesis of male infertility. In vitro studies have undoubtedly shown that spermatozoa are indeed susceptible to free radicals. However, many reports correlating ROS with sperm function impairment are based on an oxidative stress scenario created in vitro, lacking a more concrete observation of the real capacity of sperm in the production of ROS. Furthermore, sample contamination by leukocytes and the drawbacks of many dyes and techniques used to measure ROS also greatly impact the reliability of most studies in this field. Therefore, in addition to a careful scrutiny of the data already available, many aspects of the relationship between ROS and sperm physiopathology are still in need of further controlled and solid experiments before any definitive conclusions are drawn.