Sperm DNA and detection of DNA fragmentations in sperm

A 2-step remote TUNEL approach for sperm DNA fragmentation assessment. Analysis in donors and patients

OBJECTIVES

Infertility is a disease of the male or female reproductive systems. Male reproductive workup is based on routine semen analysis, although of limited value. The 2021 WHO Manual incorporated Sperm DNA Fragmentation (SDF) assessment, and highlighted the need for individual laboratories to define suitable thresholds. This study aimed to present an alternative to address this issue, determine an SDF cut-off value with fertile donors, and characterize SDF in a patient cohort and their relationship with semen parameters.

STUDY DESIGN

A service unit was established to remotely perform TUNEL assay in a 2 step-process. Semen samples were received at andrology laboratories, subjected to routine semen analysis (WHO, 2010), partially processed and transported to the service unit for SDF evaluation. Using this setting, studies were done in fertile donors (n = 15) to define the cut-off value, and in men undergoing infertility workup (n = 318).

RESULTS

A cut-off value of 9.17 % was determined with the fertile donor cohort. With this cut-off, a 64.46 % abnormal SDF incidence was determined in the patient cohort. SDF negatively correlated with sperm number, vitality and motility, and positively with abnormal morphology and male age (P < 0.05). TUNEL-positive cases depicted lower sperm quality and higher male age (P < 0.05). A similar abnormal SDF incidence was determined among patients with semen abnormalities. Asthenozoospermic and ≥40 years patient samples depicted higher (P < 0.05) SDF than those of the general population. SDF incidence was also high in normozoospermic patients.

CONCLUSIONS

Using a 2-step remote approach with a standardized procedure and an SDF cut-off value established with fertile donors, high SDF incidence in semen samples depicting normal and abnormal quality were identified in men consulting for infertility, highlighting the relevance of its evaluation as part of the male fertility workup.

Aberrant protamination in sperm correlates to anomalous nuclear and cytoplasmic architectures in infertile males with sperm dysmorphology

Aberrant sperm protamination is linked to sperm dysmorphology and nuclear chromatin condensation. Yet, its effects on sperm cytoplasmic maturation remain largely unexplored. The relationships of protamines, sperm morphology, DNA damage, and cytoplasmic remodeling were illustrated in this study to provide fresh perspectives on the mechanisms of male infertility. A total of 205 infertile males were allocated into 5 groups according to the percentage of spermatozoa exhibiting abnormal morphology within their samples. Sperm concentration, motility, abnormal sperm morphology, cytoplasmic droplets (CDs), and excess residual cytoplasm (ERC) were analyzed according to the World Health Organization manual (2010). Sperm nuclear vacuoles (NVs) were determined by propidium iodide (PI) staining. Sperm protamine expressions (P1 and P2) were detected by western blot. DNA damage was measured by acridine orange test (AOT) to calculate the proportion of sperm with single-strand DNA breaks (SSBs). Our data showed that sperm concentration and motility in infertile males significantly decreased with the severity of abnormal sperm morphology (both P < 0.01). P1 level, P1/P2 ratio, and SSB rate increased with the severity of sperm dysmorphology, whilst the P2 level decreased (all P < 0.01). NVs, CDs, and ERC were more common in males with sperm dysmorphology and positively correlated with the SSB rate (all P < 0.01). The relationships between the SSB rate and the P1/P2 ratio were also significant ( P < 0.01). Aberrant protamination may cause sperm dysmorphology and compromise male fertility by impairing sperm's nucleus and cytoplasm maturation, with the P1/P2 ratio potentially serving as a valuable indicator of sperm quality and male fertility.

Study on Sperm-Cell Detection Using YOLOv5 Architecture with Labaled Dataset

Infertility has recently emerged as a severe medical problem. The essential elements in male infertility are sperm morphology, sperm motility, and sperm density. In order to analyze sperm motility, density, and morphology, laboratory experts do a semen analysis. However, it is simple to err when using a subjective interpretation based on laboratory observation. In this work, a computer-aided sperm count estimation approach is suggested to lessen the impact of experts in semen analysis. Object detection techniques concentrating on sperm motility estimate the number of active sperm in the semen. This study provides an overview of other techniques that we can compare. The Visem dataset from the Association for Computing Machinery was used to test the proposed strategy. We created a labelled dataset to prove that our network can detect sperms in images. The best not-super tuned result is mAP 72.15.

Water-soluble Yb3+, Er3+ codoped NaYF4 nanoparticles induced SGC-7901 cell apoptosis through mitochondrial dysfunction and ROS-mediated ER stress

BACKGROUND

Nanoparticles are potential luminescent probes; among them, upconversion nanoparticles (UCNP) are currently being developed as fluorescent probes for biomedical applications. However, the molecular mechanisms of UCNP in human gastric cell lines remain poorly understood. Here, we aimed to examine UCNP cytotoxicity to SGC-7901 cells and explore its underlying mechanisms.

METHODS

The effects of 50-400 μg/mL UCNP on human gastric adenocarcinoma (SGC-7901) cells were investigated. Flow cytometry was used to evaluate reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨm), intracellular Ca²⁺ levels, and apoptosis. Activated caspase-3 and nine activities were measured; meanwhile, cytochrome C (Cyt C) in the cytosol and B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X protein (Bax), protein kinase B (Akt), phosphorylated-Akt (p-Akt), 78 kDa glucose-regulated protein (GRP78), 94 kDa glucose-regulated protein (GRP94), calpain-1, and calpain-2 protein levels were also detected.

RESULTS

UCNP inhibited the viability of SGC-7901 cells in a concentration- and time-dependent manner and increased the proportion of cell apoptosis. Exposure to UCNP enhanced the ratio of Bax/Bcl-2, elevated the level of ROS, decreased ΔΨm, increased intracellular Ca²⁺ and Cyt C protein levels, decreased the levels of phosphorylated Akt, increased the activity of caspase-3 and caspase-9, and upregulated the protein expression of GRP-78, GRP-94, calpain-1 and calpain-2 in SGC-7901 cells.

CONCLUSION

UCNP induced SGC-7901 cell apoptosis by promoting mitochondrial dysfunction and ROS-mediated endoplasmic reticulum (ER) stress, initiating the caspase-9/caspase-3 cascade.

Effect of phosphorylation of protamine-like cationic peptide on the binding affinity to DNA

Protamines are more arginine-rich and more basic than histones and are responsible for providing a highly compacted shape to the sperm heads in the testis. Phosphorylation and dephosphorylation are two events that occur in the late phase of spermatogenesis before the maturation of sperms. In this work, we have studied the effect of phosphorylation of protamine-like cationic peptides using all-atom molecular dynamics simulations. Through thermodynamic analyses, we found that phosphorylation reduces the binding efficiency of such cationic peptides on DNA duplexes. Peptide phosphorylation leads to a less efficient DNA condensation, due to a competition between DNA-peptide and peptide-peptide interactions. We hypothesize that the decrease of peptide bonds between DNA together with peptide self-assembly might allow an optimal re-organization of chromatin and an efficient condensation through subsequent peptide dephosphorylation. Based on the globular and compact conformations of phosphorylated peptides mediated by arginine-phosphoserine H-bonding, we furthermore postulate that phosphorylated protamines could more easily intrude into chromatin and participate to histone release through disruption of histone-histone and histone-DNA binding during spermatogenesis.

Correlation of sperm DNA damage with blastocyst formation: systematic review and meta-analysis

Background

The routine semen analysis fails to detect sperm DNA damage which contributes to the majority of male factor infertility. Sperm DNA fragmentation test (DFI) measures the sperm DNA damage. Blastocyst formation is an important step in IVF ± ICSI. At present, the literature lacks any data that correlates DFI and blastocyst formation.

Main body of the abstract

We searched MEDLINE and other databases till 2020 for the studies that reported on sperm DNA damage and blastocyst formation in assisted reproductive technology (ART). The outcomes analyzed were (1) a comparison of blastulation rates in high DFI and low DFI groups. (2) Comparison of blastulation rates in high DFI and low DFI groups based on (a) different sperm DNA fragmentation assays (COMET, SCD, SCSA, TUNEL), (b) different types of ART (IVF/IVF + ICSI/ICSI). 10 studies were included in this review. A non-significant increase in the blastocyst formation was observed in high DFI group (OR = 0.70; 95% CI = 0.4 to 1.21; P = 0.20) and with SCD and TUNEL assays.

Short conclusion

Our study emphasizes on sperm DNA fragmentation (sperm DNA damage) as an important marker of blastocyst formation. The results of this meta-analysis suggest that the high sperm DNA fragmentation may not adversely affect the blastocyst formation.

Protective effects of curcumin on chromatin quality, sperm parameters, and apoptosis following testicular torsion-detorsion in mice

Objective

The chief outcome of testicular torsion in clinical and experimental contexts is testicular ischemia. Curcumin, a compound with anti-inflammatory and antioxidant properties, has fascinated researchers and clinicians for its promise in the treatment of fertility diseases.

Methods

Thirty-five fully grown male mice were randomly classified into five groups: control, sham, testicular torsion, treatment group 1 (testicular torsion+short-term curcumin), and treatment group 2 (testicular torsion+long-term curcumin). Thirty-five days later, spermatozoa from the right cauda epididymis were analyzed with regard to count and motility. Toluidine blue (TB), aniline blue (AB), and chromomycin A3 (CMA3) staining assays were used to evaluate the sperm chromatin integrity. In addition, the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) test was used to assess apoptosis.

Result

Treatment group 1 exhibited a remarkably elevated sperm count compared to the testicular torsion group. Additionally, notably lower sperm motility was found in the testicular torsion group compared to the control, treatment 1, and treatment 2 groups. Staining (CMA3, AB, and TB) and the TUNEL test indicated significantly greater testicular torsion in the torsion group compared to the control group (p<0.05). The data also revealed notably lower results of all sperm chromatin assays and lower apoptosis in both treatment groups relative to the testicular torsion group (p<0.05). Significantly elevated (p<0.05) AB and TB results were noted in treatment group 1 compared to treatment group 2.

Conclusion

Curcumin can compensate for the harmful effects of testicular ischemia and improve sperm chromatin quality in mice.

The effects of broccoli and caraway extracts on serum oxidative markers, testicular structure and function, and sperm quality before and after sperm cryopreservation

Despite studies on the effects of medicinal plants on reproductive performance, the effect of extracts broccoli and caraway on serum and testicular oxidative biomarkers, testicular structure and function and sperm quality before and after cryopreservation has not been studied. Sixty-three male mice were divided into nine controlled and treated groups as follow: control, broccoli (200 mg/kg), broccoli (300 mg/kg), caraway (200 mg/kg), caraway (300 mg/kg), broccoli -caraway (200 mg/kg), broccoli (300 mg/kg)-caraway (200 mg/kg), broccoli (200 mg/kg)-caraway (300 mg/kg), broccoli-caraway (300 mg/kg). After 42 days of treatment, the animals were sacrificed and blood sample and testicular tissue were collected for biochemical and histological measurements. Sperm quality was also measured before and after cryopreservation. The results showed that the diameter and number of spermatogonium, primary spermatocytes, spermatids and sperm count were significantly increased by broccoli (300 mg/kg), while level of them were significantly decreased by caraway (300 mg/kg) compared to other groups (p < 0.01). Sperm viability and motility after thawing significantly improved by broccoli (300 mg/kg) compared to control. Testosterone levels significantly increased by broccoli (300 mg/kg) compared to control and caraway (300 mg/kg). The serum and testicular SOD and CAT activity significantly increased by broccoli (300 mg/kg) compared to other groups (p < 0.05). MDA and DNA fragmentation levels significantly increased by caraway (200 and 300 mg/kg) compared to others (p < 0.01). It can be concluded that broccoli extract in a dose-dependent manner than caraway extract could improve serum and testes oxidative biomarkers, testicular structure and function, and sperm quality before and after cryopreservation.

Sperm DNA fragmentation index with unexplained recurrent spontaneous abortion: A systematic review and meta-analysis

BACKGROUND

A high sperm DNA fragmentation index (DFI) influences human reproduction and is observed in infertile men. However, the influence of DFI on unexplained recurrent spontaneous abortion (RSA) remains controversial.

OBJECTIVE

We explored the influence of DFI on unexplained recurrent spontaneous abortion.

DATA SOURCES

We conducted a meta-analysis of DFI (assessed by sperm chromatin structure assay(SCSA), terminal deoxynucleotidyl transferase-mediated deoxyuridine (TdT)triphosphate (dUTP) nick end labeling assay(TUNEL), sperm chromatin dispersion(SCD), single cell gel electrophoresis assay(COMET assay), and acridine orange test(AOT) with unexplained RSA from the Cochrane Library, EMBASE, Pubmed and Web of Science database.

METHODS

Records were screened for eligible studies and data were extracted to an online data extraction form. The main outcome was the sperm DFI. Summary measures were reported as the mean difference(MD) and Odds Ratio(OR) with 95 % confifidence interval (CI).

RESULT

We identified 27 articles including 3, 2, 9, 9, and 8 studies using AO, COMET, SCSA, SCD and TUNEL respectively; 7 articles used qualitative methods and 21 articles used in quantitative methods. The combined MD estimates of 7 SCSA studies (MD=5.4; 95 % CI: 1.76-9.03; P<0.01), 9 SCD studies (MD=11.16; 95 % CI:6.70-15.62; P<0.01), and 8 TUNEL studies (MD=12.12; 95 % CI: 3.34-20.91; P<0.01) showed significant differences. Notably, qualitative studies showed consistent results with quantitative studies.

CONCLUSION(S)

These findings support an association between sperm DFI and recurrent pregnancy loss. Previous studies revealed that DFI negatively impacts unexplained RSA.

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.

Relationship between sperm morphology and sperm DNA dispersion

Background

The pathogenesis of teratozoospermia (<4% morphologically normal sperm cells) and the relationship between sperm morphological abnormalities and abnormal sperm nuclear DNA fragmentation, which are considered indicators of male fertility, have not been elucidated. Our research was designed to determine the prevalence of different sperm DNA fragmentation (SDF) levels in men with teratozoospermia and to establish a discriminating threshold value for SDF in assessing sperm morphology.

Methods

Basic semen characteristics and detailed sperm morphological analysis (head, neck, midpiece, and tail defects and excess residual cytoplasm) (WHO, 2010), and the nuclear sperm DNA dispersion test were performed on semen samples obtained from 523 men with teratozoospermia (n=296) and those without teratozoospermia (n=227).

Results

Subjects with abnormal sperm morphology had not only lower results for standard sperm characteristics, including detailed sperm morphological abnormalities, but also a higher proportion of sperm cells with SDF vs. men with normal sperm morphology. Moreover, significantly fewer subjects with low SDF levels (≤15%), more subjects with high SDF levels (>30%) and a higher odds ratio (OR) for having high SDF levels were found in the group of men with teratozoospermia vs. men without teratozoospermia. However, the receiving operating characteristic (ROC) curve analysis indicated that a SDF >18% was a significant negative predictive value to distinguish between men with normal sperm morphology or men with abnormal sperm morphology. The optimal area under the ROC curve (AUC) was 0.746. In the group of men with teratozoospermia, a higher incidence of men with >18% SDF and a higher OR for having >18% SDF were observed. SDF negatively correlated with sperm number, morphologically normal sperm cells, sperm motility and sperm vitality but positively correlated with the teratozoospermia index (TZI) and detailed sperm morphological abnormalities.

Conclusions

The obtained findings demonstrated that: (I) detailed sperm structural defects coexist with abnormal nuclear sperm DNA dispersion, (II) men with teratozoospermia may have a higher risk for sperm DNA damage, (III) the calculated optimal SDF value of 18% measured by the DNA sperm dispersion test is the best criterion to predict normal and abnormal sperm morphology.

Effects of cooling rates on the quality of Prochilodus lineatus (Valenciennes, 1836) sperm

This study aims to investigate the effect of different cooling rates on the semen cryopreservation of curimba (Prochilodus lineatus). Nineteen ejaculates were obtained from adults males and cryopreserved at 15°C/min (CR15), 30°C/min (CR30) (controlled temperature inside and outside straw, speed was stable during freezing) and direct freezing in liquid nitrogen vapour (~35.6°C/min) (CRNV). The straws were thawed and seminal parameters evaluated. DNA fragmentation through the comet assay was assessed. A fresh sperm sample was not frozen and used for analyses. Data were submitted to an analysis of variance (ANOVA), and means were compared by Scott-Knott test (p < 0.05) using the R Software. Mean motility percentage was 100%, and motility duration was 39.5 ± 5.7 s for the fresh sperm (subjective analysis); 58.9 ± 8.0% and 24.5 ± 5.7 s for CR15; 64.8 ± 4.8% and 26.5 ± 7.1 s for CR30; and 50.1 ± 16% and 25.7 ± 4.7 s for CRNV, respectively. Motility percentages were higher and equal between CR15 and CR30 compared to CRNV (p < 0.05). Some sperm motion kinetics, namely average path velocity (VAP) and straight line velocity (VAS), were higher for CR30 (p < 0.05), while curvilinear velocity (VCL) and velocity progression (PRO) were lower for CRNV (p < 0.05). Straightness (STR) and wobble (WOB) were the same among treatments (p > 0.05). Sperm morphology results indicated higher means for total morphological sperm alterations in CRNV. All cooling rates caused sperm DNA fragmentation, although CR30 provided a less harmful effect. This is the first report for cryopreserved P. lineatus sperm preserved under different controlled cooling rates. The cooling rate of 30°C/min is indicated for the cryopreservation of this fish sperm as it led to the lowest detrimental spermatozoa effects.