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

The paternal clock: Uncovering the consequences of advanced paternal age on sperm DNA fragmentation

The objective of the study was to investigate the relationship between advanced paternal age and sperm DNA fragmentation (SDF) levels, specifically identifying the age at which a significant increase in SDF occurs. This is a retrospective cohort study involving 4250 consecutive semen samples from patients presenting for infertility evaluation. Patients were stratified into seven age groups: < 26 (n = 36; 0.8 %), 26-30 (n = 500; 11.8 %), 31-35 (n = 1269; 29.9 %), 36-40 (n = 1268; 29.8 %), 41-45 (n = 732; 17.2 %), 46-50 (n = 304; 7.2 %), > 50 (n = 141; 3.3 %). The main outcome measures included comparing mean SDF levels throughout different age groups and assessing the prevalence of normal, intermediate, and high SDF among the age groups. A positive correlation was observed between paternal age and SDF (r = 0.17, p < 0.001). SDF remained relatively constant until the age of 35 but increased significantly beyond age 35. Mean SDF levels in the older age groups (36-40, 41-45, 46-50, and >50 years) were significantly higher than in the younger age groups (<26, 26-30, and 31-35 years) (p < 0.001). The prevalence of normal SDF was highest among the younger age groups, whereas the prevalence of high SDF was highest among the older age groups. Interestingly, the prevalence of intermediate SDF was relatively constant throughout the age groups (ranging between 29.8 % to 37.2 %). The increase in SDF after the age of 35 highlights the importance of considering male age in infertility evaluations. Assessing SDF in men over the age of 35 is crucial in couples seeking to conceive.

Impact of short abstinence versus testicular sperm on sperm DNA fragmentation: a systematic review and meta-analysis

PURPOSE

Optimal sperm DNA integrity is essential for fertilization and embryo health. Research indicates that testicular sperm (TS), obtained via TESA or TESE, typically show lower sperm DNA fragmentation (SDF) than ejaculated sperm after standard abstinence. Shortening abstinence to less than 2 days might reduce SDF, offering a less invasive and more cost-effective alternative to surgical sperm retrieval. Yet, no studies have directly compared the efficacy of shorter abstinence against TS extraction for lowering SDF. Our meta-analysis aims to address this gap by comparing SDF levels in TS to those in ejaculated sperm after a short abstinence period.

METHODS

Meta-analysis of 16 randomized controlled and prospective observational studies included 4 on TS and 12 on short abstinence ejaculation. The meta-analysis followed MOOSE guidelines, scrutinizing databases including Cochrane Library, Web of Science, Embase, MEDLINE(R), and PUMBED up to November 16, 2023. The analysis was conducted using RevMan. The observational studies' methodological quality was assessed using the Newcastle-Ottawa Scale, and the overall evidence quality was evaluated following the GRADE criteria. To compare short ejaculation duration and TS (are not directly compared in the literature) for SDF levels, we analyzed relevant data from studies of each method. We adjusted the participant numbers in the TS group by 1/3 and included each TS study three times, to perform a comparison against the short duration studies which were in a ratio of 1:3. This approach maintained an unaltered cumulative subject count for the meta-analysis of TS studies.

RESULTS

A total of 641 patients were included, comprising 120 and 521 patients with SDF measurements following TS and ejaculation after a short abstinence period, respectively. The studies had varied inclusion criteria, with not all patients having an initial elevated SDF. Some studies had incomplete details on age and other demographics. However, the mean ± SD age of 93 TS patients was 38.15 ± 5.48 years vs. 37.7 ± 6.0 years of 444 short abstinence patients, demonstrating no significant difference (P = 0.544). Short abstinence durations ranged from 1 to 48 h. Diverse DNA fragmentation tests were used: TUNEL assay in three testicular sperm studies, SCD assay in one, and in the short abstinence group, four used TUNEL and six used SCD assays, along with one each using SCSA and Halosperm. The mean ± SD SDF was lower in the TS group than in the short abstinence group (mean difference - 9.48, 95%CI - 12.45 to - 6.52, P < 0.001, I2 = 85%). Sensitivity analysis revealed that no single study significantly influenced the results. Employing the GRADE criteria, the initial assessment categorized the overall quality of evidence as low due to the observational nature of the acquired data. All studies were of medium to high quality.

CONCLUSION

This study suggests testicular sperm may be better than ejaculated sperm for improving SDF in infertility cases. Direct comparisons are needed, before deeming short abstinence less effective. Future research should directly compare reproductive outcomes using both methods.

Clinical Utility of Sperm Function Tests in Predicting Male Fertility: A Systematic Review

Routine semen analysis provides considerable information regarding sperm parameters; however, it is not solely adequate to predict male fertility potential. In the past two decades, several advance sperm function tests have been developed. The present systematic review intends to assess the clinical utility of available advance sperm function tests in predicting the male fertility potential. A systematic literature search was conducted as per PRISMA guidelines using PubMed, MEDLINE, Google Scholar, and Cochrane Library. Different keywords either singly or in combination were used to retrieve the relevant articles related to sperm function tests, male fertility, and pregnancy outcomes. A total of 5169 articles were obtained, out of which 110 meeting the selection criteria were included in this review. The majorly investigated sperm function tests are hypo-osmotic swelling test, acrosome reaction test, sperm capacitation test, hemizona binding assay, sperm DNA fragmentation test, seminal reactive oxygen species test, mitochondrial dysfunction tests, antisperm antibody test, nuclear chromatin de-condensation (NCD) test, etc. The different advance sperm function tests analyse different aspects of sperm function. Hence, any one test may not be helpful to appropriately predict the male fertility potential. Currently, the unavailability of high-quality clinical data, robust thresholds, complex protocols, high cost, etc., are the limiting factors and prohibiting current sperm function tests to reach the clinics. Further multi-centric research efforts are required to fulfil the existing lacunas and pave the way for these tests to be introduced into the clinics.

An Alternative Application of Magnetic-Activated Cell Sorting: CD45 and CD235a Based Purification of Semen and Testicular Tissue Samples

Magnetic activated cell sorting (MACS) is a well-known sperm selection technique, which is able to remove apoptotic spermatozoa from semen samples using the classic annexinV based method. Leukocytes and erythrocytes in semen samples or in testicular tissue processed for in vitro fertilization (IVF) could exert detrimental effects on sperm. In the current study, we rethought the aforementioned technique and used magnetic microbeads conjugated with anti-CD45/CD235a antibodies to eliminate contaminating leukocytes and erythrocytes from leukocytospermic semen samples and testicular tissue samples gained via testicular sperm extraction (TESE). With this technique, a 15.7- and a 30.8-fold reduction could be achieved in the ratio of leukocytes in semen and in the number of erythrocytes in TESE samples, respectively. Our results show that MACS is a method worth to reconsider, with more potential alternative applications. Investigations to find molecules labeling high-quality sperm population and the development of positive selection procedures based on these might be a direction of future research.

Gaussian clustering and quantification of the sperm chromatin dispersion test using convolutional neural networks

Sperm DNA fragmentation is a sign of sperm nuclear damage. The sperm chromatin dispersion (SCD) test is a reliable and economical method for the evaluation of DNA fragmentation. However, the cut-off value for differentiation of DNA fragmented sperms is fixed at 1/3 with limited statistical justification, making the SCD test a semi-quantitative method that gives user-dependent results. We construct a collection of deep neural networks to automate the evaluation of bright-field images for SCD tests. The model can detect valid sperm nuclei and their locations from the input images captured with a 20× objective and predict the geometric parameters of the halo ring. We construct an annotated dataset consisting of N = 3120 images. The ResNet 18 based network reaches an average precision (AP50) of 91.3%, a true positive rate of 96.67%, and a true negative rate of 96.72%. The distribution of relative halo radii is fit to the multi-peak Gaussian function (p > 0.99). DNA fragmentation is regarded as those with a relative halo radius 1.6 standard deviations smaller than the mean of a normal cluster. In conclusion, we have established a deep neural network based model for the automation and quantification of the SCD test that is ready for clinical application. The DNA fragmentation index is determined using Gaussian clustering, reflecting the natural distribution of halo geometry and is more tolerable to disturbances and sample conditions, which we believe will greatly improve the clinical significance of the SCD test.

Carboxylated Poly-L-lysine Potentially Reduces Human Sperm DNA Fragmentation after Freeze-Thawing, and Its Function Is Enhanced by Low-Dose Resveratrol

Sperm DNA fragmentation (SDF) that occurs during the freezing-thawing of sperm may negatively impact the treatment outcomes of assisted reproductive technologies (ART). In a previous study, we developed a human sperm cryopreservation reagent containing carboxylated poly-L-lysine (CPLL) that reduced SDF after freeze-thawing compared with clinically popular cryopreservation reagents containing human serum albumin. However, it is unclear whether CPLL reduces SDF, as it differed from the constituents of the commercial cryopreservation reagents used for comparison. Therefore, here, we examined whether CPLL reduces the SDF of human sperm and evaluated reactive oxygen species (ROS) levels and lipid peroxidation (LPO), which are the causes of SDF; mitochondrial injury, ROS production; and impaired sperm motility. Furthermore, optimal antioxidants and their concentrations that could further enhance the reduction in SDF were determined for future clinical application in ART and underwent the same functional evaluations. CPLL can reduce SDF via inhibition of intracytoplasmic ROS and LPO. Furthermore, the addition of 0.1 mM resveratrol avoided the enhancement of SDF, which potentially affects mitochondrial and cytoplasmic ROS and LPO. This novel human sperm cryopreservation reagent containing CPLL and resveratrol has the potential to improve treatment outcomes in ART using frozen sperm.

Unraveling the Impact of Sperm DNA Fragmentation on Reproductive Outcomes

In recent years, there has been a growing interest in identifying subcellular causes of male infertility, and sperm DNA fragmentation (SDF) research has been at the forefront of this focus. DNA damage can occur during spermatogenesis due to faulty chromatin compaction or excessive abortive apoptosis. It can also happen as sperm transit through the genital tract, often induced by oxidative stress. There are several methods for SDF testing, with the sperm chromatin structure assay, terminal deoxynucleotidyl transferase d-UTI nick end labeling (TUNEL) assay, comet assay, and sperm chromatin dispersion test being the most commonly used. Numerous studies strongly support the negative impact of SDF on male fertility potential. DNA damage has been linked to various morphological and functional sperm abnormalities, ultimately affecting natural conception and assisted reproductive technology outcomes. This evidence-based review aims to explore how SDF influences male reproduction and provide insights into available therapeutic options to minimize its detrimental impact.

Evaluation of Sperm DNA Fragmentation Using Two Different Methods: TUNEL via Fluorescence Microscopy, and Flow Cytometry

Background and Objectives: Sperm DNA fragmentation refers to any break in one or both of the strands of DNA in the head of a sperm. The most widely used methodologies for assessing sperm DNA fragmentation are the sperm chromatin structure assay (SCSA), the sperm chromatin dispersion assay (SCD), the single-cell gel electrophoresis assay (SCGE-comet), and the terminal-deoxynucleotidyl-transferase (TdT)-mediated dUTP nick end labelling (TUNEL) assay. The aim of this study was to compare the efficiency and sensitivity of the analysis of sperm DNA fragmentation using TUNEL via fluorescence microscopy, and flow cytometry. Materials and Methods: Semen samples were collected and analyzed for standard characteristics using light microscopy, and for sperm DNA fragmentation using both TUNEL via fluorescence microscopy, and flow cytometry. Results: There were no significant differences in the values of the sperm DNA fragmentation index (DFI) obtained when the analysis was performed using TUNEL or flow cytometry (p = 0.543). Spearman's correlation analysis revealed a significant negative correlation between sperm motility (%) and sperm DNA fragmentation (p < 0.01), as well as between sperm concentration and sperm DNA fragmentation (p < 0.05). The Mann-Whitney U test showed no significant difference in the DFI among couples with repeated implantation failure (RIF) and miscarriages (p = 0.352). Conclusions: Both methods (TUNEL via fluorescence microscopy, and flow cytometry) have a high efficiency and sensitivity in accurately detecting sperm DNA fragmentation, and can be effectively used to assess male fertility.

Impact of waterpipe and tobacco cigarette smoking on global DNA methylation and nuclear proteins genes transcription in spermatozoa: a comparative investigation

BACKGROUND

Waterpipe smoking is harmful and dangerous, and it is a growing threat to public health.

OBJECTIVES

This study was performed to evaluate the influence of waterpipe smoking on global DNA methylation, DNA fragmentation, and protamine deficiency in spermatozoa compared to cigarette heavy smokers and nonsmokers, and to determine whether the transcription levels of spermatozoa nuclear proteins genes 'PRM1, PRM2, and H2BFWT' in waterpipe smokers are different compared to cigarette heavy smokers and nonsmokers.

METHODS

A total of 900 semen samples were collected from males with a mean age of 32.5 ± 6.3 years (300 waterpipe smokers, 300 cigarette heavy smokers, and 300 nonsmokers). The nucleic acids were isolated from purified spermatozoa, and then the global DNA methylation and transcription levels of the PRM1, PRM2, and H2BFWT genes were assessed using ELISA and qPCR, respectively.

RESULTS

A significant increase was found in the level of global DNA methylation (8.6 ± 0.6 ng/μl vs. 7.1 ± 0.6 ng/μl and 4.7 ± 0.6 ng/μl, p < 0.001), protamine deficiency (72.8 ± 15.3 vs. 51.7 ± 19.2 and 15.3 ± 5.9%, p < 0.001), and DNA fragmentation (73.4 ± 13.4 vs. 50.5 ± 18.9 and 9.3 ± 4.3%, p < 0.001) in waterpipe smokers compared to cigarette heavy smokers and nonsmokers. A significant increase was shown in the transcription levels of PRM1, PRM2, and H2BFWT genes in waterpipe smokers compared to cigarette heavy smokers and nonsmokers (p < 0.001). A down-regulation was found in the transcription level of these genes in different smoker groups compared to nonsmokers (<0.001).

CONCLUSION

This study suggests that waterpipe smoking is more harmful than cigarette smoking on semen parameters, global DNA methylation, and transcription of nuclear protein genes.

Effect of hubble-bubble smoking on global DNA methylation and transcription levels of protamine and histone genes in human spermatozoa

This study was conducted to assess the impact of hubble-bubble smoking on global DNA methylation, DNA fragmentation; protamine deficiency of spermatozoa, and to determine whether the transcription levels of the protamine and histone genes are different in hubble-bubble smokers compared to nonsmokers. Five hundred semen samples were collected from males with an average age of 32.2 ± 6.1 years (300 hubble-bubble smokers "60%" and 200 nonsmokers "40%"). The nucleic acid was isolated from purified sperm, then ELISA and qPCR were used to evaluate the global DNA methylation and transcription level of protamine and histone, respectively. A significant elevation in global DNA methylation, protamine deficiency, and DNA fragmentation was found in hubble-bubble smokers compared to nonsmokers (P < 0.0001). A significant decline was shown in transcription levels of protamine and histone genes in hubble-bubble compared to nonsmokers (P < 0.0001). Additionally, a down-regulation in the transcription levels of protamine and histone was revealed in hubble-bubble compared to nonsmokers with fold change (0.0001 and 0.007, respectively). In conclusion, this study provided proof that hubble-bubble smoking has a negative impact on global DNA methylation, DNA fragmentation, protamine deficiency, and the transcription of protamine and histone genes in spermatozoa, and these findings influence negatively males' fecundity.

Risk of embryo aneuploidy is affected by the increase in sperm DNA damage in recurrent implantation failure patients under ICSI-CGH array cycles

This study investigates the relationship between sperm DNA damage in recurrent implantation failure (RIF) patients treated with comparative genomic hybridisation array-intracytoplasmic sperm injection (CGH array-ICSI) cycles and embryo aneuploidy screening. Forty-two RIF couples were selected. Sperm DFI was measured using TUNEL by flow cytometry. Two groups were defined as follows: (i) sperm with high DFI (> 20%); and (ii) low DFI (< 20%). Semen parameters, total antioxidant capacity (TAC), and malondialdehyde formation (MDA) were also measured in both groups. Following oocyte retrieval and ICSI procedure, blastomere biopsy was performed at the 4th day of development and evaluated with CGH-array. The high DFI group had a significant (p = 0.04) increase in the number of aneuploid embryos compared to the low one. According to Poisson regression results, the risk of aneuploidy embryos in the high DFI group was 55% higher than the low DFI group (RR = 1.55; 95% CI = 1.358-1.772). Moreover, chromosomal analysis showed an elevation of aneuploidy in chromosomes number 16 and 20 in the high DFI group compared to the low DFI group (p < 0.05). The high DFI in RIF patients may significantly affect the risk of aneuploidy embryos. Therefore, embryo selection by CGH-array should be considered for couples with high levels of sperm DNA fragmentation.

A systematic review identifying fertility biomarkers in semen: a clinical approach through Omics to diagnose male infertility

OBJECTIVE

To identify the most robust molecular biomarkers in sperm and seminal plasma for the diagnosis of male infertility, and to evaluate their clinical use.

DESIGN

Systematic review.

SETTING

Not applicable.

PATIENT(S)

Accessible studies reporting well-defined (in)fertile populations and semen molecular biomarkers were included in this review.

INTERVENTION(S)

A systematic search of the literature published in MEDLINE-PubMed and EMBASE databases was performed, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

MAIN OUTCOME MEASURE(S)

The primary outcome was the content, expression, or activity of molecular biomarkers in human semen samples. Only studies reporting a receiver-operating characteristic (ROC) analysis values were included.

RESULT(S)

Eighty-nine studies were included. Direct evaluation of sperm DNA damage has high potential as a diagnostic biomarker of fertility and assisted reproductive technology outcomes (area under the curve [AUCs] median = 0.67). Regarding strand break-associated chromatin modifications, γH2AX levels show good predictive value for the diagnosis of male infertility (AUCs median = 0.93). Some noncoding ribonucleic acid (RNA) exhibit excellent predictive values; miR-34c-5p in semen is the most well-characterized and robust transcriptomic biomarker (AUCs median = 0.78). While many proteins in semen show fair diagnostic value for sperm quality and fertilizing capacity, the levels of some, such as TEX101, in seminal plasma have an excellent diagnostic potential (AUCs median = 0.69). Although individual metabolites and metabolomic profiles in seminal plasma present good predictive value, the latter seem to be better than the former when inferring sperm quality and fertilizing capacity.

CONCLUSION(S)

The current review supports that some Omics (e.g., DNA structure and integrity, genomics and epigenomics, transcriptomics, metabolomics, and proteomics) could be considered relevant molecular biomarkers that may help identify infertility etiologies and fertilization prognosis with cost-effective, simple, and accurate diagnosis.

Sperm DNA integrity and male infertility: a narrative review and guide for the reproductive physicians

Background and Objective

Conventional semen analysis (SA) remains an essential tool in the initial male fertility evaluation and subsequent follow-up. However, it neither provides information about the functional status of spermatozoa nor addresses disorders such as idiopathic or unexplained infertility (UI). Recently, assessment of sperm DNA fragmentation (SDF) has been proposed as an extended sperm test that may help overcome these inherent limitations of basic SA. In this review, we aim to: (I) discuss the pathophysiological aspects of SDF, including natural repair mechanisms, causes, and impact on reproductive outcomes; (II) explain different assessment tools of SDF, and describe potential therapeutic options to manage infertile men with high SDF; and (III) analyse the strengths, weaknesses, opportunities and threats (SWOT) of current research on the topic.

Methods

This review was constructed from original studies, systematic reviews and meta-analyses that were published over the years up until August 2021, related to the various aspects of SDF.

Key Content and Findings

Different mechanisms lead to high SDF, including defective chromatin packaging, apoptosis, and seminal oxidative stress. The relevance of sperm DNA integrity to male fertility/infertility has been supported by the frequent observation of high levels of SDF in infertile men, and in association with risk factors for infertility. Additionally, high SDF levels have been inversely correlated with the outcomes of natural pregnancy and assisted reproduction. Terminal deoxynucleotidyl transferase dUTP nick end labelling, sperm chromatin structure assay, sperm chromatin dispersion, and Comet assay are four commonly used assays for measurement of SDF. Addressing lifestyle risks and underlying conditions, antioxidants, hormonal therapy, and advanced sperm selection techniques have all been proposed as potential therapeutic options to lower SDF.

Conclusions

The sum of literature provides evidence of detrimental effects of high SDF on both natural and assisted fertility outcomes. Standardization of the techniques used for assessment of SDF and their incorporation into the work up of infertile couples may have significant implications on the future management of a selected category of infertile men with high SDF.

Relationship between Serum Vitamin D in Male, Sperm Function and Clinical Outcomes in Infertile Men Candidate for ICSI: A Cohort Study

Background

Today, vitamin D deficiency (VDD) is one of the major health issues around the world and VDD is associated with several diseases. This study was conducted to find the relationship between vitamin D status in male's serum with sperm function and clinical outcomes in infertile men candidate for intracytoplasmic sperm injection (ICSI).

Materials and Methods

In this cohort study, different parameters of male fertility such as sperm parameters, oxidative stress, and sperm chromatin status were evaluated in sperm samples of 30 infertile couples candidate for ICSI. Clinical outcomes like fertilization, embryo quality, and implantation were also assessed. Data were analyzed using SPSS Statistics 25.0 software. Besides, assessment of the correlation between aforementioned parameters with the level of serum vitamin D, in this study, ICSI candidates were divided into three groups [individuals with sufficient vitamin D levels (>30 ng/ml), insufficient vitamin D levels (between 20-29 ng/ml), and VDD (<20 ng/ml)]. The aforementioned parametesr were also compared between these study groups.

Results

Analysis of all the data revealed a significant correlation between the level of vitamin D with sperm concentration (P=0.000, r=0.5), sperm count (P=0.03, r=0.31) and sperm reactive oxygen species (ROS) level (P=0.000, r=-0.77). Moreover, comparing clinical outcomes within study groups showed a significant difference in implantation rate between sufficient and other groups (insufficient and deficient) (P=0.02).

Conclusion

Considering the association between sperm concentration and level of ROS with vitamin D and, higher implantation rate in individuals with vitamin D sufficient group compared to other two groups, our data call for vitamin D supplementation as part of male infertility treatment. But considering our sample size, further research is needed to verify these findings.

Association among sperm chromatin condensation, sperm DNA fragmentation and 8-OHdG in seminal plasma and semen parameters in infertile men with oligoasthenoteratozoospermia

The present study aimed to investigate the clinical role of standard sperm diagnosis parameters (sperm concentration, motility, morphology) as well as aniline blue staining of histones, 8-OHdG, TUNEL assay were performed on semen samples in infertile men with oligoasthenoteratozoospermia (OAT). Thirty-two infertile and ten proven fertile men were included in the study. Chromatin condensation sperm in infertile men was significantly lower compared to the fertile men (p < 0.0001). Age, sperm concentration, morphology and motility were significantly negatively correlated with chromatin condensation (p < 0.05). However, no significant correlations among the chromatin condensation, SDF and sperm DNA damage were detected in terms of 8-OHdG concentration.

Reliability of the sperm chromatin dispersion assay to evaluate sperm deoxyribonucleic acid damage in men with infertility

OBJECTIVE

To investigate the intraindividual agreement of the sperm chromatin dispersion (SCD) assay results to assess sperm DNA fragmentation (SDF) in men with infertility.

DESIGN

Diagnostic test reliability study.

SETTING

Andrology laboratories.

PATIENT(S)

A total of 219 men with infertility.

INTERVENTION(S)

Sperm DNA fragmentation assessment in two ejaculates of the same subjects within a 3-month interval, using the SCD assay performed and analyzed by the same observers under similar testing conditions.

MAIN OUTCOME MEASURE(S)

Cohen's κ statistics to assess the degree of agreement between the pairs of results after converting the nominal SCD values into categorical data, that is, normal (<20%), intermediate (21%-29%), and high (≥30%) SDF rates. We also assessed the pairs of results using reliability measures for numerical variables (intraclass correlation coefficient for consistency using the two-way mixed-effects model and Bland-Altman plots).

RESULT(S)

The degree of agreement in classifying patients according to normal and pathological SDF classes was overall substantial (κ = 0.632; 95% confidence interval [CI], 0.546-0.718). A total of 76.7% of individuals were classified under the same class using paired ejaculates. The agreement rate was highest (approximately 80%) in ejaculates initially classified as either normal or high and lowest (approximately 60%) among those with intermediate SDF levels. The frequency of intermediate SDF ejaculates downgraded to normal or upgrade to high SDF classes in the second test was similar (approximately 20%). The intraclass correlation coefficient was 0.856 (95% CI, 0.812-0.887), and the mean difference between the pairs of observations was 0.80% (95% CI, -0.72 to 2.23), indicating no systematic difference between paired observations.

CONCLUSION(S)

Our study indicates a substantial intraindividual agreement of paired SCD assay results to classify men with infertility into three SDF categories: normal, intermediate, and high. The reliability of the SCD assay was adequate and exceeded 0.80 using two ejaculates analyzed within a 3-month interval under similar conditions. Although this evidence overall supports a single SCD test for patient classification using predefined SDF thresholds, particularly when the first test shows normal or high SDF levels, one in four men will have discordant values in paired ejaculates. Clinicians should be judicious when using SDF test results in decision-making.

Carboxylated Poly-l-Lysine as a Macromolecular Cryoprotective Agent Enables the Development of Defined and Xeno-Free Human Sperm Cryopreservation Reagents

In human sperm cryopreservation, test yolk buffer and human serum albumin have been used as permeating macromolecular-weight cryoprotectants. In clinical reproductive medicine, human serum albumin is frequently used because of low risks of zoonoses and allergic reactions. However, the risk of allogeneic infectious diseases exists, and the supply may be unstable because human serum albumin is derived from human blood. Therefore, the development of xeno-free human sperm cryopreservative reagents that could overcome the aforementioned problems is warranted. We succeeded in developing a new xeno-free and defined sperm cryopreservation reagent containing glycerol, carboxylated poly-l-lysine, and raffinose. The cryopreservation reagent was not significantly different in terms of sperm motility, viability, and DNA fragmentation and was comparable in performance to a commercial cryopreservation reagent containing human serum albumin. Moreover, the addition of saccharides was essential for its long-term storage. These results may help elucidate the unknown function of macromolecular-weight permeating cryoprotective agents.

DNA Fragmentation in Human Spermatozoa and Pregnancy Rates after Intrauterine Insemination. Should the DFI Threshold Be Lowered?

Sperm DNA fragmentation index (DFI) can be analyzed by a flow cytometric assay after treatment with acid and acridine orange. In this prospective, cohort study, the value of DFI was determined in a semen analysis collected before fertility treatment (baselineDFI) in 146 couples and during 1–3 intrauterine inseminations (IUI) in 211 couples (511 cycles). The pregnancy rate (PR)/cycle was 9.9% if baselineDFI was >10 and 21.7% if baselineDFI was ≤10, (p < 0.005). The live birth rate (LBR)/cycle was 5% if baselineDFI was >10 and 14.2% if baselineDFI was ≤10 (p < 0.005). PR/patient was 23.1% if baselineDFI was >10 and 45.5% if baselineDFI was ≤10 (p < 0.005). LBR/patient was 12.4% if baselineDFI was >10 and 34% if baselineDFI was ≤10 (p < 0.005). When isolating non-stimulated IUI cycles and couples with female age < 35, a significant difference in PR and LBR between couples with high DFI and low DFI was seen. Results suggest that DFI > 10 could advice against timed coitus and non-stimulated IUI cycles. Analysis for DFI performed before treatment provides information about PR and LBR after IUI.

Mitochondrion-Dependent Apoptosis Is Essential for Rickettsia parkeri Infection and Replication in Vector Cells

Apoptosis is an innate immune response induced by infection in eukaryotes that contributes significantly to protection from pathogens. However, little is known about the role of apoptosis in the interactions of arthropod vectors with the rickettsiae that they transmit. Rickettsia spp. are vector-borne obligately intracellular bacteria and display different degrees of virulence in their eukaryotic hosts. In this study, we found that infection with Rickettsia parkeri (Rp) activated the apoptosis pathway in an Amblyomma americanum tick cell line (AAE2), as evidenced by the loss of phospholipid membrane asymmetry and DNA fragmentations. Additionally, infection with Rp also led to apoptosis activation in cell lines of different tick species. Interestingly, suppressing apoptosis decreased Rp infection and replication, while the activation of apoptosis increased Rp accumulation at the early stage of infection. Moreover, mitochondrion-dependent apoptosis was essential for Rp infection and replication in vector cells, and apoptosis induction required intracellular rickettsia replication. We further showed that Rp utilizes two different survival strategies to modulate apoptosis in the arthropod vectors and mammalian host cells. There was no direct correlation between apoptosis activation in vector cells and rickettsial pathogenicity. These novel findings indicate a possible mechanism whereby apoptosis facilitates infection and replication of a Rickettsia sp. in an arthropod vector. These results contribute to our understanding of how the vector's responses to pathogen infection affect pathogen replication and therefore transmission.

IMPORTANCE Rickettsioses, infections caused by the genus Rickettsia, are among the oldest known infectious diseases. Ticks are essential arthropod vectors for rickettsiae, and knowledge about the interactions between ticks, their hosts, and pathogens is fundamental for identifying drivers of tick-borne rickettsioses. Despite the rapid development in apoptosis research with rickettsiae, little is known regarding the role of apoptosis in the interactions between Rickettsia spp., vertebrate hosts, and arthropod vectors. Here, we demonstrated that mitochondrion-dependent apoptosis is essential for rickettsial infection and replication in vector cells and that apoptosis induction requires intracellular rickettsial replication. However, rickettsial pathogenicity is not linked with apoptosis activation in tick cells. Our findings improve understanding of the apoptosis mechanism in arthropods exploited by rickettsiae and also the potential to discover specific targets for new vaccines and drugs to prevent or treat rickettsial infections.

Sperm DNA fragmentation testing: Summary evidence and clinical practice recommendations

We herein summarise the evidence concerning the impact of sperm DNA fragmentation in various clinical infertility scenarios and the advances on sperm DNA fragmentation tests. The collected evidence was used to formulate 41 recommendations. Of these, 13 recommendations concern technical aspects of sperm DNA fragmentation testing, including pre-analytical information, clinical thresholds and interpretation of results. The remaining 28 recommendations relate to indications for sperm DNA fragmentation testing and clinical management. Clinical scenarios like varicocele, unexplained infertility, idiopathic infertility, recurrent pregnancy loss, intrauterine insemination, in vitro fertilisation/intracytoplasmic sperm injection, fertility counselling for men with infertility risk factors and sperm cryopreservation have been contemplated. The bulk evidence supporting the recommendations has increased in recent years, but it is still of moderate to low quality. This guideline provides clinicians with advice on best practices in sperm DNA fragmentation testing. Also, recommendations are provided on possible management strategies to overcome infertility related to sperm DNA fragmentation, based on the best available evidence. Lastly, we identified gaps in knowledge and opportunities for research and elaborated a list of recommendations to stimulate further investigation.

European Association of Urology Guidelines Panel on Male Sexual and Reproductive Health: A Clinical Consultation Guide on the Indications for Performing Sperm DNA Fragmentation Testing in Men with Infertility and Testicular Sperm Extraction in Nonazoospermic Men

Accumulating evidence has highlighted the contribution of oxidative stress and sperm DNA fragmentation (SDF) in the pathophysiology of male infertility. SDF has emerged as a novel biomarker of risk stratification for patients undergoing assisted reproductive technologies. Studies have also supported the use of testicular over ejaculated sperm at the time of intracytoplasmic sperm injection, as testicular sperm may have lower SDF than ejaculated samples. The European Association of Urology Working Panel on Male Sexual and Reproductive Health provides an evidence-based consultation guide on the indications for SDF testing in male infertility and also for testicular sperm extraction (TESE) in nonazoospermic men. We present the limitations and advantages of SDF testing and a framework to ensure that it is appropriately utilised in clinical practice. Furthermore, we critically appraise the current literature advocating the use of TESE in nonazoospermic men. PATIENT SUMMARY: This article reviews the evidence supporting the use of sperm DNA fragmentation testing in the assessment of male infertility and testicular sperm extraction in nonazoospermic men.

Semiquantitative promoter methylation of MLH1 and MSH2 genes and their impact on sperm DNA fragmentation and chromatin condensation in infertile men

To investigate the semiquantitative methylation alterations of MLH1 and MSH2 and the possible association among methylation of MLH1 and MSH2, sperm DNA fragmentation and sperm chromatin condensation in idiopathic oligoasthenoteratozoospermic men. Seventy-five idiopathic infertile men and 52 fertile and/or normozoospermic men were included in the study. SDF was analysed using the TUNEL assay in semen samples of 100 men. Promoter methylation of MLH1 and MSH2 genes was assessed by semiquantitative methylight analysis in semen samples of 39 and 40 men respectively. Sperm chromatin condensation was evaluated using aniline blue staining in 114 men. MLH1 promoter methylation was positively correlated with the percentage of aniline blue positive spermatozoa (r = 0.401, p = 0.0188). On the other hand, MSH2 promoter methylation was negatively correlated with sperm concentration and total sperm count (r = -0.421, p = 0.0068 and r = 0.4408, p = 0.009 respectively). The percentage of aniline blue positive spermatozoa in the control group was significantly lower than in the OAT group (p < 0.0001) and negatively correlated with total sperm count (r = -0.683, p < 0.0001), progressive sperm motility (r = -0.628, p < 0.0001), total motility (r = -0.639, p < 0.0001) and normal morphology (r = -0.668, p < 0.0001). Promoter methylation profile of MLH1 and MSH2 genes may play role on sperm DNA packaging and conventional semen parameters respectively.

Silibinin-hydroxypropyl-β-cyclodextrin (SLB-HP-β-CD) complex prevents apoptosis in liver and kidney after hepatic ischemia-reperfusion injury

BACKGROUND

We investigated the protective effect of silibinin on rat liver and kidney after hepatic inschemia/reperfusion (I/R) injury.

METHODS AND MATERIALS

Sixty three male Wistar-type rats (median age 13 weeks; average weight 314 g) were subjected to I/R injury of the liver. They were randomly divided into three groups: Sham (n = 7), Control (C, n = 28) and Silibinin (Si, n = 28). The last group received intravenously silibinin. The C and Si groups were each subdivided in four subgroups according to euthanasia times (i.e., 60, 120, 180, 240 min). We assessed expression of caspase-3 and TUNEL assay, and biochemical and histological parameters.

RESULTS

At 240 min, expression of caspase-3 and TUNEL assay were statistically significantly lower in the Si compared to the C group for both liver and kidney. SGOT and SGPT were also statistically significantly lower in the Si than in the C group at all time points. Histological parameters of the liver were also improved in the Si group.

CONCLUSION

Silibinin was found to exhibit a protective effect on liver and kidney after hepatic I/R injury. The present results are encouraging for further studies and future clinical application.

An update on the techniques used to measure oxidative stress in seminal plasma

Reactive oxygen species (ROS) are produced in significant amounts by spermatozoa and leucocytes. They are necessary to carry out various physiological functions such as sperm capacitation, hyperactivation, acrosome reaction, sperm-zona binding and cellular signalling pathways. Oxidative stress (OS) results when the ROS levels overwhelm the available antioxidant reserve. A number of direct and indirect tests have been developed to assess oxidative stress. In this manuscript, we discuss these common direct and indirect tests as well as their advantages and disadvantages. Tests measuring sperm dysfunction secondary to oxidative stress such as lipid peroxidation, DNA fragmentation and protein alterations are also described.

Critical evaluation of two models of flow cytometers for the assessment of sperm DNA fragmentation: an appeal for performance verification

Lack of standardized, reproducible protocols and reference values is among the challenges faced when using new or upgraded versions of instruments in reproductive laboratories and flow cytometry. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay combined with flow cytometry routinely used for diagnostic measurement of sperm DNA fragmentation (SDF) is a unique example. Any change in the setting of the standard instrument, including upgrades of hardware or software, can lead to different results and may affect clinicians’ decision for treatment. Therefore, we compared TUNEL results of SDF obtained from a standard (C6) flow cytometer with a newer version of the same instrument (C6 Plus) and examined the cutoff, sensitivity, and specificity without calibration (adjustment) and after adjustment. Identical sperm preparation and matched acquisition settings were used to examine the performance of two flow cytometers. The strength of agreement of the results between the two observers was also assessed. After adjustment of the settings, overall concordance became high and the two cytometers showed 100% positive and negative predictive value with 100% area under the curve. The overall correlation coefficient observed between C6 and C6 Plus was highly significant (P < 0.0001; r = 0.992; 95% confidence interval [CI]: 0.982–0.997). After adjustment, the two cytometers showed very high precision of 98% and accuracy of >99%. The interobserver agreement on C6 flow cytometer for the two observers was 0.801 ± 0.062 and 0.746 ± 0.044 for C6 Plus. We demonstrated a strong agreement between the samples tested on the two flow cytometers after calibration and established the robustness of both instruments.

TUNEL assay-Standardized method for testing sperm DNA fragmentation

Sperm DNA integrity is important for normal functions such as fertilization, implantation, pregnancy and fetal development. Sperm DNA fragmentation (SDF) is more common in infertile men and may be responsible for poor reproductive function. Although there are a number of tests available to measure SDF, the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-nick end labelling TUNEL) assay using flow cytometry is becoming more popular to measure the sperm DNA fragmentation. It is a direct test that measures both single- and double- DNA strand breaks. In this review, we describe the protocol, quality control and measurement of sperm DNA fragmentation using a benchtop flow cytometer. We also briefly discuss the factors that can affect the results, challenges and clinical implications of TUNEL in assessing male infertility.

Evolving a Thermostable Terminal Deoxynucleotidyl Transferase

Terminal deoxynucleotidyl transferase (TdT) catalyzes template free incorporation of arbitrary nucleotides onto single-stranded DNA. Due to this unique feature, TdT is widely used in biotechnology and clinical applications. One particularly tantalizing use is the synthesis of long de novo DNA molecules by TdT-mediated iterative incorporation of a 3' reversibly blocked nucleotide, followed by deblocking. However, wild-type (WT) TdT is not optimized for the incorporation of 3' modified nucleotides, and TdT engineering is hampered by the fact that TdT is marginally stable and only present in mesophilic organisms. We sought to first evolve a thermostable TdT variant to serve as backbone for subsequent evolution to enable efficient incorporation of 3'-modified nucleotides. A thermostable variant would be a good starting point for such an effort, as evolution to incorporate bulky modified nucleotides generally results in lowered stability. In addition, a thermostable TdT would also be useful when blunt dsDNA is a substrate as higher temperature could be used to melt dsDNA. Here, we developed an assay to identify thermostable TdT variants. After screening about 10 000 TdT mutants, we identified a variant, named TdT3-2, that is 10 °C more thermostable than WT TdT, while preserving the catalytic properties of the WT enzyme.

Best laboratory practices and therapeutic interventions to reduce sperm DNA damage

Conventional semen analysis is considered the cornerstone investigation for infertile men. Nonetheless, this routine test does not provide information on important sperm functions like sperm DNA fragmentation (SDF). Abnormalities of human spermatozoal nucleus and chromatin have a detrimental impact on both natural and assisted reproductive outcomes. In vivo, SDF results from abnormalities in chromatin compaction, abortive apoptosis and oxidative stress, while in vitro, a number of factors may be implicated. Various SDF testing methods are available, and the most commonly utilised assays include terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL), sperm chromatin dispersion (SCD) test, sperm chromatin structure assay (SCSA) and Comet assay. SDF testing has shown beneficial effects on treatment decision-making; however, its routine use in the initial evaluation of infertile men is still not recommended. One of the treatment options to reduce sperm DNA damage is the use of antioxidants. Despite the documented improvement in semen parameters and sperm DNA integrity following antioxidant therapy, no definitive recommendation is reached due to lack of large, well-designed, randomised, placebo-controlled trials assessing their exact role in male factor infertility. The objectives of this review article are to illustrate the aetiologies of SDF, to describe the effects of SDF on male factor fertility, to explore the common techniques utilised in SDF testing, to review the clinical indications for SDF testing and to review the effect of antioxidant therapy as a method to alleviate SDF.

Comparative analysis of tests used to assess sperm chromatin integrity and DNA fragmentation

Male infertility has a complex etiology, and many times, the cause is unknown. While routine semen analysis provides an overview of basic semen parameters, such as sperm concentration, motility, viability and morphology, a significant overlap of these parameters has been reported in fertile and infertile men. Moreover, conventional semen parameters do not reveal the cellular or molecular mechanisms of sperm dysfunctions leading to infertility. Therefore, sperm functional parameters, including sperm chromatin integrity, are evaluated to provide information on subtle sperm defects that are not routinely identified. Incomplete or defective sperm chromatin condensation increases the susceptibility of the sperm DNA to oxidative damage or other factors. To evaluate sperm chromatin integrity, different methods with varying degrees of diagnostic and prognostic capabilities are available. Among these assays, SCSA, TUNEL and SCD assays are most commonly used. While these assays rather evaluate the DNA directly for damages, the aniline blue and chromomycin A3 stains test for the quality of chromatin condensation. Thus, this review discusses and compares different methods used to evaluate sperm chromatin integrity and condensation, and their inclusion in the routine evaluation of the male infertility.

Expression of RXFP2 receptor on human spermatozoa and the anti-apoptotic and antioxidant effects of insulin-like factor 3

Insulin-like factor 3 (INSL3) has an important role in the human reproductive system; however, its detailed function is still mysterious. We aimed to investigate the possibility of expression of RXFP2 receptor on human spermatozoa and to determine the anti-apoptotic and antioxidant mechanism derived the binding of INSL3 and RXFP2. In this experimental study, the expression/location of the RXFP2 receptor was determined on the spermatozoa of fertile and infertile men. Twenty samples from 20 fertile men were collected and divided into 6 parts (control group, and five groups treated with INSL3 10, 100, 250, 500, 1,000 ng/ml). DNA damage, active caspase, reactive oxygen species (ROS) and sperm parameters were evaluated by TUNEL, flow cytometry, optical microscope and computer-assisted sperm analysis. The expression of RXFP2 was confirmed by Western blot. Immunocytochemistry illustrated that this receptor is expressed in the posterior half of the spermatozoa's head. The INSL3 at concentrations of 500 and 1,000 ng/ml reduced the active caspase and mitochondrial ROS, and also reduced DNA fragmentation at 1,000 ng/ml. Besides, INSL3 500 and 1,000 ng/ml significantly increased the sperm motility. This study confirmed the presence of RXFP2 receptor in fertile and infertile men's spermatozoa, indicating the highly dose-dependent efficacy of the INSL3, which may have promising impacts on the in-vitro fertilisation outcomes.

Diagnostic value of advanced semen analysis in evaluation of male infertility

Conventional semen analysis is the standard of care to initially evaluate the fertility status of a male patient. However, it has some limitations and among these are failure to correctly identify the aetiology underlying fertility problems, intra- and inter-observer variability and incomplete information about sperm function. Considering these drawbacks, advanced semen tests have been developed to assess male infertility, including sperm function tests, oxidative stress (OS) and sperm DNA fragmentation (SDF) tests. This review illustrates the commonly utilised sperm function techniques, along with the assays used to assess SDF and OS and their diagnostic value.

A randomised trial comparing conventional semen parameters, sperm DNA fragmentation levels and satisfaction levels between semen collection at home and at the clinic

The aim of the randomised trial was to compare conventional semen parameters, sperm DNA fragmentation levels and satisfaction levels between semen samples collected at home and at the clinic. We recruited 110 men with a history of infertility for at least 1 year from the outpatient andrology clinic. Each man collected two semen samples, one at home and one at the clinic. Men were randomly assigned into the home first (n = 55) or clinic first (n = 55) groups. The primary outcome was sperm concentration. There was no significant difference in sperm concentration, sperm DNA fragmentation levels or other conventional semen parameters between home first and clinic first samples (p > .05), while satisfaction levels were significantly higher for home first samples (p < .01). Consistent results were obtained when comparing home-collected and clinic-collected samples within individuals. Men can be offered the option to collect semen samples at home for examination or assisted reproduction without compromising semen quality, especially for those with difficulty in producing semen samples at the clinic.

Conventional semen analysis and advanced sperm function tests in diagnosis and management of varicocele

Clinical varicoceles are a common cause of male infertility and affect sperm parameters as measured in a conventional semen analysis. Varicocelectomy has been shown in prospective studies to improve semen parameters in men with a clinical varicocele. Clinical varicoceles are also a well-known source of oxidative stress which may affect the quality of spermatozoa. Spermatozoa are particularly susceptible to oxidative stress due to a limited capacity for DNA repair. The susceptibility of spermatozoa to oxidative stress is modulated by a balance between ROS and antioxidants, which can be quantified by various laboratory assays. Varicocelectomy has been consistently shown to reduce both ROS and sperm DNA fragmentation, and various assays should be utilised in the diagnosis and treatment of infertile men with a clinical varicocele.

Designing Aptamer-Gold Nanoparticle-Loaded pH-Sensitive Liposomes Encapsulate Morin for Treating Cancer

This study proposes the synthesis of a type of anticancer nanoparticle, aptamers and Au nanoparticle (Apt-Au)-modified Morin pH-sensitive liposome (MSL), which exhibits targeting properties. Tumors are difficult to cure because their microenvironment varies from that of normal tissue; its pH is lower than that of normal tissue, which generally impedes the effectiveness of drugs. Thus, pH-responsive drugs have attracted extensive attention. Gold nanoparticles (AuNPs) show potential as drug carriers because of their small size, good biocompatibility, easy surface modification, and strong cell penetration. Apt-Au@MSL exhibits excellent monodispersity and tumor-targeting properties and can be released in partly acidic environment via dialysis. We screened our model cancer cell by MTT assay and found that SGC-7901 cells can effectively suppress proliferation. In vivo results demonstrate that the administration of Apt-Au@MSL could inhibit tumor growth in xenograft mouse models. H&E staining and TUNEL assay further confirmed that Apt-Au@MSL can promote tumor apoptosis. Apt-Au@MSL may induce apoptosis by triggering overproduction of reactive oxygen species (ROS) and regulating multiple signal crosstalk. Both blood biochemistry tests and H&E staining suggested that these materials exhibit negligible acute toxicity and good biocompatibility in vivo. With its powerful function, Apt-Au@MSL can be used as a target-based anticancer material for future clinical cancer treatment.

DNA fragmentation index (DFI) as a measure of sperm quality and fertility in mice

Although thousands of genetically modified mouse strains have been cryopreserved by sperm freezing, the likelihood of cryorecovery success cannot be accurately predicted using conventional sperm parameters. The objective of the present study was to assess the extent to which measurement of a sperm DNA fragmentation index (DFI) can predict sperm quality and fertility after cryopreservation. Using a modified TUNEL assay, we measured and correlated the DFI of frozen-thawed sperm from 83 unique mutant mouse strains with sperm count, motility and morphology. We observed a linear inverse correlation between sperm DFI and sperm morphology and motility. Further, sperm DFI was significantly higher from males with low sperm counts compared to males with normal sperm counts (P < 0.0001). Additionally, we found that viable embryos derived using sperm from males with high DFI (62.7 ± 7.2% for IVF and 73.3 ± 8.1% for ICSI) failed to litter after embryo transfer compared to embryos from males with low DFI (20.4 ± 7.9% for IVF and 28.1 ± 10.7 for ICSI). This study reveals that measurement of DFI provides a simple, informative and reliable measure of sperm quality and can accurately predict male mouse fertility.

Tracking research trends and hotspots in sperm DNA fragmentation testing for the evaluation of male infertility: a scientometric analysis

BACKGROUND

This article describes the research trends in sperm DNA fragmentation (SDF) over the past 20 years (1999-2018) using a scientometric approach.

METHODS

A stepwise approach was adopted to retrieve scientometric data (articles per year, authors, affiliations, journals, countries) from Scopus and analyze the publication pattern of SDF with reference to key areas of research in the field of Andrology.

RESULTS

A total of 2121 articles were retrieved related to SDF. Our data revealed an increasing research trend in SDF (n = 33 to n = 173) over the past 20 years (R² = 0.894). Most productive country in publications was the USA (n = 450), while Agarwal A. (n = 129) being the most productive author. Most of the articles in SDF were primarily focused on lifestyle (n = 157), asthenozoospermia (n = 135) and varicocele (130). Mechanistic studies on SDF were published twice as much as prognostic/diagnostic studies, with significant emphasis on oxidative stress. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was the most widely used technique to evaluate SDF. Publications on SDF related to assisted reproductive techniques also showed a linear increasing trend (R² = 0.933).

CONCLUSIONS

Our analysis revealed an increasing trend in SDF publications predominantly investigating lifestyle, asthenozoospermia and varicocele conditions with TUNEL being the most widely used technique. A substantial increase in research is warranted to establish SDF as prognostic/diagnostic parameter to evaluate clinical scenarios and ART outcomes.

Oxidation Stress-Mediated MAPK Signaling Pathway Activation Induces Neuronal Loss in the CA1 and CA3 Regions of the Hippocampus of Mice Following Chronic Cold Exposure

Chronic stress can damage homeostasis and induce various primary diseases. Although chronic cold stress is becoming an increasing problem for people who must work or live in extreme environments, risk-induced diseases in the central nervous system remain unstudied. Male C57BL/6 mice were exposed to an environment of 4 °C, 3 h per day for 1, 2, and 3 weeks and homeostasis in the hippocampus and neuronal apoptosis were evaluated by Western blotting, immunohistochemistry, TdT-mediated dUTP Nick-End Labeling (TUNEL) staining, and immunofluorescence. The phenomena of oxidation stress, MAPK signaling pathway activation, anti-oxidation protein release, neuronal apoptosis increases, and neuronal proliferation inhibition were demonstrated in the CA1 and CA3 regions of mouse hippocampal tissues following cold exposure. We speculated that these phenomena were mediated by the MAPK pathway and were closely linked with oxidative stress in the hippocampus. This study provides novel concepts regarding neurodegenerative diseases, suggesting that chronic cold stress may be a critical factor to induce neurodegenerative diseases.

Sperm DNA fragmentation: causes and identification

Sperm DNA fragmentation is referred to as one of the main causes of male infertility. Failures in the protamination process, apoptosis and action of reactive oxygen species (ROS) are considered the most important causes of DNA fragmentation. Action of ROS or changes in sperm protamination would increase the susceptibility of sperm DNA to fragmentation. Routine semen analysis is unable to estimate sperm chromatin damage. Sperm DNA integrity influences sperm functional capability, therefore tests that measure sperm DNA fragmentation are important to assess fertility disorders. Actually, there is a considerable number of methods for assessing sperm DNA fragmentation and chromatin integrity, sperm chromatin stability assay (SCSA modified), sperm chromatin dispersion (SCD), comet assay, transferase dUTP nick end labelling (TUNEL); and protamine evaluation in sperm chromatin assay, such as toluidine blue, CMA3, protamine expression and evaluation of cysteine radicals. This review aims to describe the main causes of sperm DNA fragmentation and the tests commonly used to evaluate sperm DNA fragmentation.

Famotidine does not affect human sperm fertility characteristics (motility, viability and DNA integrity) in vitro

Famotidine, a histamine-2 receptor antagonist, is commonly used to relieve the acid-related gastrointestinal diseases; however, its effect on human sperm parameters, and hence on sperm function, is still undetermined. Here, we intended to measure human sperm motility, viability, and DNA integrity of ejaculated human sperm in the presence of famotidine at 0, 0.1, 1 and 10 mM concentrations in vitro. Forty-nine semen samples of normal count, motility, and morphology were included in this study. Sperm motility was assessed using Makler counting chamber and a phase contrast optics (200× magnification), whereas sperm viability was assessed using eosin-nigrosin staining procedure. The effect of famotidine on sperm DNA integrity was measured using flow cytometry. Famotidine at 0.1, 1 or 10 mM had insignificant effect on human sperm motility (progressive, p = .9594; and total, p = .8420), sperm viability (p = .6471), and content of DNA breaks in sperm (p > .05) compared with the control. In conclusion, famotidine at 0.1, 1 or 10 mM did not alter human sperm motility, viability or DNA integrity in vitro. Although, these findings indicate safety of famotidine in human sperm, further in vivo studies are required to establish the drug's safety.

TUNEL assay: Establishing a sperm DNA fragmentation cut-off value for Egyptian infertile men

Male factor infertility is responsible for half of all infertility cases. Conventional semen analysis is inadequate to evaluate male fertility. Sperm DNA fragmentation (SDF) test can be done by: direct methods such as Terminal deoxynucleotidyl transferase dUTP Nick-End Labeling (TUNEL) and Comet assay, or indirect like Sperm Chromatin Structure Assay (SCSA) and Sperm Chromatin Dispersion (SCD). TUNEL assay measures both single- and double-strand breaks and is technically less demanding, while SCSA tests for the susceptibility for nuclear DNA denaturation and samples should be sent to the reference lab. Studies showed that a single cut-off value does not fit all. Therefore, this study aimed at establishing a cut-off value to discriminate between fertile and infertile Egyptian men. We enrolled 354 infertile men and 40 proven fertile volunteers.TUNEL assay was performed using Apo-Direct kit and bench top flow cytometer.The calculated SDF cut-off value was 20.3% with a sensitivity of 96.6% and specificity of 87.5%, and the overall accuracy of the test was 95.7%. Sperm DNA fragmentation Test using TUNEL assay is valuable tool for male infertility evaluation, and it assists in offering the best treatment options based on it's results.

DNA fragmentation in concert with the simultaneous assessment of cell viability in a subfertile population: establishing thresholds of normality both before and after density gradient centrifugation

PURPOSE

TUNEL assay is the most common, direct test for sperm chromatin integrity assessment. But, lack of standardized protocols makes interlaboratory comparisons impossible. Consequently, clinical thresholds to predict the chance of a clinical pregnancy also vary with the technique adopted. This prospective study was undertaken to assess the incidence of sperm DNA fragmentation in a subfertile population and to establish threshold values of normality as compared to a fertile cohort, both before and after density gradient centrifugation in the total and vital fractions.

METHOD

Men presenting at a university hospital setup for infertility treatment. DNA damage via TUNEL assay was validated on fresh semen samples, as conventional semen parameters, to reduce variability of results.

RESULTS

Total DNA fragmentation in the neat semen was significantly higher in the subfertile group, but the vital fraction was not significantly different between the two cohorts. After gradient centrifugation, DNA fragmentation increased significantly in the total fraction of the subfertile group but decreased significantly in the vital fraction. In the fertile cohort, there was a non-significant increase in total fragmentation and in the vital fraction the trend was unclear.

CONCLUSIONS

Estimating total and vital sperm DNA fragmentation, after density gradient centrifugation, increased both the sensitivity and the specificity, thereby lowering the number of false negatives and false positives encountered. These findings provide opportunities to investigate the significance of the total and the vital fractions after different assisted reproductive technologies.