DNA fragmentation of human sperm can be detected by ligation-mediated real-time polymerase chain reaction

Effects of Sargassum virgatum extracts on the testicular measurements, genomic DNA and antioxidant enzymes in irradiated rats

BACKGROUND

Oxidative stress and reactive oxygen species (ROS) are primarily responsible for the development of male infertility after exposure to γ-irradiation. The present work aimed to assess the ameliorative and therapeutic roles of the aqueous and ethanolic extracts of the edible seaweed Sargassum virgatum (S. virgatum) on spermatogenesis and infertility in γ-irradiated Wistar rats.

MATERIALS AND METHODS

Induction of infertility was performed by exposing the rats to 137Cs-gamma rays, using a single dose of 3.5 Gy. γ-irradiated rats were given the S. virgatum ethanolic (S. virgatum-EtOH) and aqueous extracts intraperitoneally on a daily base for two consecutive weeks at doses of 100 and 400 mg/kg body weight (b.wt.) for each seaweed extract. Morphometric data of the testes, semen quality indices, antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and glutathione peroxidase (GPx), and deoxyribonucleic acid (DNA) fragmentation were assessed. The results obtained were taken during two-time intervals of 15 and 60 days from the commencement of the algal treatments. In vitro antioxidant assays and polyphenolic compounds of S. virgatum were characterized.

RESULTS

Significant negative changes in the semen quality and morphometric data of the testes, as well as remarkable DNA fragmentation, were detected in the irradiated rats compared to the control. The levels of the endogenous antioxidant enzymes (SOD, CAT, GSH, and GPx) were also significantly diminished. Nonetheless, treatments of γ-irradiated rats with the S. virgatum-EtOH and aqueous extracts significantly improved the above-mentioned enzymes, in addition to noteworthy amendments in the dimensions of the testes, the semen quality, as well as the DNA structure.

CONCLUSIONS

The ameliorative potency of S. virgatum to cure γ-irradiation-induced male infertility, particularly 400 mg/kg ethanolic extract for 60 days, is the result of the consistent therapeutic interventions of its potent antioxidant and anti-apoptotic polyphenols, particularly protocatechuic, p-hydroxybenzoic, rosmarinic, chlorogenic, cinnamic and gentisic acids, as well as the flavonoids catechin, hesperidin, rutin and quercetin. Besides its high-value nutraceutical importance, S. virgatum could be a natural candidate for developing well-accepted radioprotectant products capable of treating γ-irradiation-induced male infertility.

Effects of Pulsed-Wave Photobiomodulation Therapy on Human Spermatozoa

BACKGROUND AND OBJECTIVES

Previous studies reported that photobiomodulation (PBM) positively affects the mitochondrial respiratory chain in sperm, resulting in improved motility and velocity. As laser settings are not yet fully established, the present study aimed at optimizing PBM on human sperm. In addition, possible side-effects of PBM on sperm DNA fragmentation level and acrosomal integrity have been analyzed.

STUDY DESIGN/MATERIALS AND METHODS

A pulsed laser-probe (wavelength 655 nm, output power 25 mW/cm², impulse duration 200 nanoseconds) was used. Native fresh liquefied semen samples underwent radiation with energy doses of 0 (control), 4, 6, and 10 J/cm². Sperm parameters were assessed at 0, 30, 60, 90, and 120 minutes after radiation using a computer-assisted sperm analysis system. Motility and velocity of sperm from asthenozoospermic patients (n = 42) and normozoospermic controls (n = 22) were measured. The amount of DNA strand breaks was analyzed using ligation-mediated quantitative polymerase chain reaction in patients with asthenozoospermia (n = 18) and normozoospermia (n = 13). Post-irradiance acrosomal integrity was investigated using flow cytometry based on CD46 protein expression (n = 7).

RESULTS

Exposure to laser energy-doses of 4 and 6 J/cm² improved sperm motility and velocity in asthenozoospermic patients. PBM exhibited no significant effect on DNA fragmentation level and expression of CD46 serving as a biomarker for acrosome integrity.

CONCLUSION

PBM improves sperm motility parameters by maintaining DNA and acrosome integrity and, therefore, represents a promising new tool for assisted reproductive therapy. In particular, improving sperm motility in asthenozoospermic patients by PBM in future may contribute to increasing the chance for successful intrauterine insemination. The present trial has no clinical registration number, as only in vitro studies were performed. The study was approved by the local ethics committee and performed according to the Declaration of Helsinki. Lasers Surg. Med. © 2021 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC.

Progress in Research on Sperm DNA Fragmentation

With the increasing incidence of male infertility, routine detection of semen is insufficient to accurately assess male fertility. Infertile men, who have lower odds of conceiving naturally, exhibit high levels of sperm DNA fragmentation (SDF). The mechanisms driving SDF include abnormal spermatogenesis, oxidative stress damage, and abnormal sperm apoptosis. As these factors can induce SDF and subsequent radical changes leading to male infertility, detection of the extent of SDF has become an efficient routine method for semen analysis. Although it is still debated, SDF detection has become a research hotspot in the field of reproductive medicine as a more accurate indicator for assessing sperm quality and male fertility. SDF may be involved in male infertility, reproductive assisted outcomes, and growth and development of offspring. The effective detection methods of SDF are sperm chromatin structure analysis (SCSA), terminal transferase-mediated dUTP end labeling (TUNEL) assay, single-cell gel electrophoresis (SCGE) assay, and sperm chromatin dispersion (SCD) test, and all of these methods are valuable for assisted reproductive techniques. Currently, the preferred method for detecting sperm DNA integrity is SCSA. However, the regulation network of SDF is very complex because the sperm DNA differs from the somatic cell DNA with its unique structure. A multitude of molecular factors, including coding genes, non-coding genes, or methylated DNA, participate in the complex physiological regulation activities associated with SDF. Studying SDF occurrence and the underlying mechanisms may effectively improve its clinical treatments. This review aimed to outline the research status of SDF mechanism and detection technology-related issues, as well as the effect of increased SDF rate, aiming to provide a basis for clinical male infertility diagnosis and treatment.

Exposure to non-ionizing electromagnetic radiation of public risk prevention instruments threatens the quality of spermatozoids

The use of artificial insemination in cattle breeding has evolved to global extent, and insemination doses are often shipped via air transport which requires strict radiation-based examinations. For the determination of effect of non-ionizing radiation (NIR), to which are beings frequently exposed due to protection of airport or cultural event security, freshly ejaculated and cryopreserved bovine spermatozoa were used as experimental model. Following radiation with hand-held metal detector in various exposition times (0, 10 s, 15, 30 and 60 min-groups FR, FR10, FR15, FR30 and FR60) the spermatozoa underwent motility and DNA fragmentation analyses. Study on cryoconserved semen treated with NIR was performed in time intervals 0, 10 s, 1 and 5 min (insemination doses radiated before cryoconservation-CB, CB10, CB1, CB5; samples radiated after freezing-CA, CA10, CA1 and CA5). Fresh semen and insemination doses radiated after cryoconservation showed significantly lower total and progressive motility. No effect on motility parameters was detected in semen extended with cryopreservative medium and radiated prior to freezing. Surprisingly, NIR showed a potential to stimulate spermatozoa velocity; however, the effect was modulated throughout the post-thawing incubation. Based on the DNA fragmentation assay, sperm DNA stayed intact. Present study underlines the potential harm of NIR, which is frequently used in everyday life, with overall adverse impact on human and animal reproduction. Current study also points out on interesting short-term spermatozoa stimulation induced by NIR.

Paternal lifestyle factors in relation to semen quality and in vitro reproductive outcomes

This prospective-cohort study aimed at investigating the influence of paternal lifestyle factors on semen parameters and intracytoplasmic sperm injection (ICSI) outcomes. The influence of paternal lifestyle factors on seminal quality and ICSI outcomes was investigated in male patients undergoing conventional semen analysis. Cigarette smoking negatively influenced semen volume (B: -0.417, slope: 1.570, p = 0.047), sperm count/ml (B: -7.363, slope: 52.298, p = 0.014), total sperm count (B: -4.43, slope: 178.165, p = 0.023), total motile sperm count (B: -1.38, slope: 100.276, p = 0.045) and SDF (B: 0.014, slope: 9.767, p = 0.033). Alcohol consumption negatively influenced sperm count/ml (B: -12.527, slope: 42.255, p = 0.040) and sperm DNA fragmentation (B: 5.833, slope: 9.680, p = 0.002). There were no significant influences of other paternal lifestyle factors. Cigarette smoking negatively influenced the fertilisation rate (B: -1.349, slope: 21.950, p = 0.039) and the blastocyst formation rate (B: -14.244, slope: 28.851, p = 0.025). Alcohol consumption negatively influenced fertilisation rate (B: -3.617, slope: 20.138, p = 0.041) and blastocyst formation rate (B: -34.801, slope: 30.044, p = 0.042). Cigarette smoking and alcohol consumption appear to reduce semen quality, fertilisation and blastocyst formation rates; thus, it would be wise to recommend that male partners reconsider their lifestyle during in vitro reproduction treatment.

Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay using bench top flow cytometer for evaluation of sperm DNA fragmentation in fertility laboratories: protocol, reference values, and quality control

PURPOSE

The purpose of this study is to provide a detailed protocol and quality control steps for measuring sperm DNA fragmentation (SDF) by terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL) assay using a new bench top flow cytometer, determine the reference value of SDF, and assess sensitivity, specificity, and distribution of SDF in infertile men and controls with proven and unproven fertility.

METHODS

Semen specimens from 95 controls and 261 infertile men referred to a male infertility testing laboratory were tested for SDF by TUNEL assay using Apo-Direct kit and a bench top flow cytometer. Percentage of cells positive for TUNEL was calculated. Inter- and intraobserver variability was examined. TUNEL cutoff value, sensitivity, specificity, and distribution of different cutoff values in controls and infertile patients were calculated.

RESULTS

The reference value of SDF by TUNEL assay was 16.8 % with a specificity of 91.6 % and sensitivity of 32.6 %. The positive and negative predictive values were 91.4 and 33.1 %, respectively. The upper limit of DNA damage in infertile men was significantly higher (68.9 %) than that in the controls (19.6 %).

CONCLUSIONS

TUNEL assay using flow cytometry is a reproducible and easy method to determine SDF. At a cutoff point of 16.8 %, the test showed high specificity and positive predictive value. The results of this test could identify infertile men whose sperm DNA fragmentation does not contribute to their infertility and confirm that a man who tests positive is likely to be infertile due to elevated sperm DNA fragmentation.