Sperm chromatin structure assay (SCSA): a tool in diagnosis and treatment of infertility

Frequency and spectrum of mutations in human sperm measured using duplex sequencing correlate with trio-based de novo mutation analyses

De novo mutations (DNMs) are drivers of genetic disorders. However, the study of DNMs is hampered by technological limitations preventing accurate quantification of ultra-rare mutations. Duplex Sequencing (DS) theoretically has < 1 error/billion base-pairs (bp). To determine the DS utility to quantify and characterize DNMs, we analyzed DNA from blood and spermatozoa from six healthy, 18-year-old Swedish men using the TwinStrand DS mutagenesis panel (48 kb spanning 20 genic and intergenic loci). The mean single nucleotide variant mutation frequency (MF) was 1.2 × 10- 7 per bp in blood and 2.5 × 10- 8 per bp in sperm, with the most common base substitution being C > T. Blood MF and substitution spectrum were similar to those reported in blood cells with an orthogonal method. The sperm MF was in the same order of magnitude and had a strikingly similar spectrum to DNMs from publicly available whole genome sequencing data from human pedigrees (1.2 × 10- 8 per bp). DS revealed much larger numbers of insertions and deletions in sperm over blood, driven by an abundance of putative extra-chromosomal circular DNAs. The study indicates the strong potential of DS to characterize human DNMs to inform factors that contribute to disease susceptibility and heritable genetic risks.

Assessing testicular morphofunctionality under Roundup WG® herbicide exposure in zebrafish

Glyphosate-based herbicides, like Roundup WG® (RWG) used for a range of crops, such as corn, soybean, coffee, sugarcane, rice, apple, and citrus, can reach aquatic ecosystems and impact non-target organisms like fish. Thus, the fish were exposed to three RWG concentrations plus one negative control, which represents the concentration allowed for inland Brazilian waters and concentrations found in surface water worldwide (0.0, 0.065, 0.65, and 6.5 mg a.i./L) for 7 and 15 days. Morphological analysis revealed significant alterations in the testicular structure, particularly in Sertoli cell extensions and cytoplasmic bridges between germ cells. Subcellular compartments also displayed alterations, including dilated mitochondria and the loss of electron density and autophagic vesicles. Gene transcript levels related to autophagy and steroidogenic regulation were upregulated in exposed fish. Germ cell quality was also affected, increasing ROS (reactive oxygen species) production and DNA fragmentation. The study highlighted the RWG reproductive toxicity, providing valuable insights into understanding the morphofunctional alterations in somatic and germ cells of Danio rerio. In conclusion, the environmental relevant concentrations used in this study were toxic to male somatic and germ cells, which raises a concern about the concentrations considered safe for human and animal use.

Mean number of DNA breakpoints: illuminating sperm DNA integrity and in vitro fertilization outcomes

OBJECTIVE

To verify the capacity of the mean number of DNA breakpoints (MDB) for evaluating sperm integrity and its relationship with in vitro fertilization (IVF) outcomes.

DESIGN

Retrospective cohort study.

SETTING

Reproductive center in a tertiary hospital.

PATIENT(S)

All men whose female partners underwent IVF from March to October 2022 in the reproductive center.

INTERVENTION(S)

The MDB and DNA fragmentation index (DFI) were used to assess sperm DNA integrity. The patients were stratified into two groups according to MDB and DFI cutoffs: sperm DNA-normal and sperm DNA-impaired.

MAIN OUTCOME MEASURES

Semen parameters: concentration, progressive motility (PR), MDB, and the DFI; IVF outcome measures: two pronuclei (2-PN), fertilization rate, fertilization cleavage rate, high-quality embryo rate, biochemical pregnancy rate, clinical pregnancy rate, and implantation rate.

RESULTS

Sperm MDB had a higher negative correlation with PR compared with the DFI (r = -0.43; r = -0.37, respectively). Sperm MDB did not have a statistical correlation with sperm concentration, whereas the DFI correlated significantly with concentration (r = -0.17; r = -0.27, respectively). Logistic regression analysis controlling for age and semen concentration demonstrated that an increase in MDB increased the risk of asthenospermia (odds ratio = 1.018, 95% confidence interval [CI] 1.003-1.034). An increasing DFI also increased the risk of asthenospermia (odds ratio = 1.044, 95% CI 1.002-1.087). The MDB showed a stronger clinical relevance with sperm PR than the DFI, as indicated using the area under the curve values (0.754, 95% CI 0.649-0.859 vs. 0.691, 95% CI 0.556-0.825). A threshold of the MDB >0.37 nM was calculated to define sperm DNA-impaired. Comparison of IVF results showed that the high-quality embryo rate (χ2 = 13.00) was significantly lower in the DNA-impaired group than in the DNA-normal group stratified using the MDB, although there were no significant differences in IVF outcomes in DFI-stratified groups.

CONCLUSION

The MDB has been verified to correlate closely with semen PR and may serve as a predictive parameter for IVF outcomes. Rigorous prospective studies are required to explore MDB performance and to further validate and reinforce the potential application of MDB as a parameter for male infertility.

Fluorescent enzyme-based biosensor for sensitive analysis of DNA damage in cryopreserved sperm

The freeze-thaw process can induce irreversible structural and functional changes in human sperm, particularly sperm DNA damage. Selecting a more accurate and sensitive detection method for evaluating sperm DNA integrity is crucial. To accurately assess sperm DNA integrity following the freeze-thaw process and significantly improve the clinical and scientific utilization of cryopreserved sperm. In this study, we utilized a novel fluorescent biosensor, assisted by terminal deoxynucleotidyl transferase (TdT) and Endonuclease IV, to detect DNA breakpoints during sperm cryopreservation. We evaluated the biosensor's performance by comparing it with the conventional DNA fragmentation index (DFI) measured using sperm chromatin structure analysis (SCSA). The cryopreserved group exhibited a significantly higher sperm DFI compared to the fresh group. No significant difference was observed between the antioxidant group and the cryopreserved group. However, the new method revealed a significant reduction in the number of DNA breakpoints in the antioxidant group compared to the cryopreserved group. The novel biosensor demonstrated superior accuracy and effectiveness in assessing sperm DNA integrity during cryopreservation compared to the conventional SCSA method. We believe that the biosensor holds significant potential for widespread use in the field of reproductive medicine.

A DNA Methylation Perspective on Infertility

Infertility affects a significant number of couples worldwide and its incidence is increasing. While assisted reproductive technologies (ART) have revolutionized the treatment landscape of infertility, a significant number of couples present with an idiopathic cause for their infertility, hindering effective management. Profiling the genome and transcriptome of infertile men and women has revealed abnormal gene expression. Epigenetic modifications, which comprise dynamic processes that can transduce environmental signals into gene expression changes, may explain these findings. Indeed, aberrant DNA methylation has been widely characterized as a cause of abnormal sperm and oocyte gene expression with potentially deleterious consequences on fertilization and pregnancy outcomes. This review aims to provide a concise overview of male and female infertility through the lens of DNA methylation alterations.

Novel sperm chromatin dispersion test with artificial intelligence-aided halo evaluation: A comparison study with existing modalities

BACKGROUND

Sperm chromatin dispersion test is a common and inexpensive technique to assess sperm DNA fragmentation, but its subjectivity in assessing a small number of spermatozoa is a disadvantage.

OBJECTIVES

To study the efficacy of a new sperm chromatin dispersion test kit (R10) combined with an artificial intelligence-aided halo-evaluation platform (X12) and compare the results to those of existing sperm DNA fragmentation testing methods.

MATERIALS AND METHODS

Semen samples from normozoospermic donors (n = 10) and infertile men with abnormal semen parameters (n = 10) were enrolled. DNA fragmentation indices were examined by multiple assays, including R10, Halosperm G2 (G2), sperm chromatin structure assay, and terminal deoxynucleotidyl transferase deoxynucleotidyl transferase nick end labeling. In R10 assay, the DNA fragmentation indices were obtained both manually (manual R10) and by X12 (AI-R10). The obtained DNA fragmentation indices were analyzed by agreement analyses.

RESULTS

The DNA fragmentation indices obtained by manual R10 and those obtained by AI-R10 showed a strong significant correlation (r = 0.97, p < 0.001) and agreement. The number of spermatozoa evaluated by AI-R10 was 2078 (680-5831). The DNA fragmentation indices obtained by manual R10 and AI-R10 both correlated with those of G2 (r = 0.90, p < 0.001; r = 0.88, p < 0.001). Between the AI-R10 and G2 results, Passing-Bablok regression showed no systematic or proportional difference, and Bland-Altman plots revealed overall agreement and a mean bias of 6.3% with an SD of 6.9% (95% limit of agreement: -7.2% to 19.9%). AI-R10 and sperm chromatin structure assays showed systematic differences with a mean bias of -1.9%, while AI-R10 and terminal deoxynucleotidyl transferase deoxynucleotidyl transferase nick end labeling revealed proportional differences with a mean bias of -10.7%.

CONCLUSIONS

The novel sperm chromatin dispersion kit and artificial intelligence-aided platform demonstrated significant correlation and agreement with existing sperm chromatin dispersion methods by assessing greater number of spermatozoa. This technique has the potential to provide a rapid and accurate assessment of sperm DNA fragmentation without technical expertise or flow cytometry.

Explaining the Unexplained: Examining the Predictive Value of Semen Parameters, Sperm DNA Fragmentation and Metal Levels in Unexplained Infertility

Background

There is ongoing research to find an optimum modality to predict male fertility potential.

Aims

To compare the semen parameters, sperm DNA damage and seminal metal levels of Zinc, Lead and Aluminium among the male partners of couples with unexplained infertility and men with proven fertility.

Settings and Design

Prospective case-control study at a tertiary level teaching hospital.

Materials and Methods

One hundred male partners of couples with unexplained subfertility and 50 men with proven fertility were included in the study. Male partners of unexplained infertility couples and fertile men were compared for their semen parameters, sperm DNA Fragmentation Index (DFI) and seminal metal levels in semen.

Statistical Analysis Used

Chi-square test, Student's t-test, sensitivity and specificity analysis, binomial logistic regression analysis.

Results

Fertile men had statistically significantly higher mean progressive sperm motility than male partners of unexplained infertility (53.12 ± 9.89% vs. 44.81 ± 19.47%, P = 0.005). Semen volume and sperm concentration were comparable among the cases and control population. The mean sperm DFI was significantly lower among fertile men (10.83 ± 6.28 vs. 21.38 ± 10.28, P < 0.0001). Plotting the receiver-operating characteristic curve the threshold for discrimination was calculated to be 18% DFI. The sensitivity specificity and overall accuracy were 43%, 84% and 56.67%, respectively when the DFI cut-off was set at 18%. Zinc concentration in the semen had a strong positive correlation (Point Biserial correlation coefficient = 0.831) with fertility, whereas lead and aluminium had a moderate negative correlation.

Conclusion

Conventional semen analysis had limited differentiating ability for unexplained infertility. The sperm DFI may be employed for explanatory purposes among couples with unexplained subfertility. A lower discriminatory threshold of DFI (18%) has better overall accuracy as opposed to a 30% cutpoint for unexplained subfertility. Among metals, Zinc was strongly correlated with fertility status.

Double strand DNA breaks in sperm: the bad guy in the crowd

PURPOSE

The main objective of this opinion paper was to bring to light and enhance our understanding of the amount of double-strand DNA breaks in sperm and whether there is a threshold of no return when considering repair by the oocyte/embryo.

METHODS

A brief review of literature related to the theories proposed for the appearance of double-strand breaks in human spermatozoa. Further commentary regarding their detection, how oocytes or embryos may deal with them, and what are the consequences if they are not repaired. Finally, a strategy for dealing with patients who have higher levels of double-strand DNA breaks in sperm is proposed by reviewing and presenting data using testicular extracted sperm.

RESULTS

We propose a theory that a threshold may exist in the oocyte that allows either complete or partial DNA repair of impaired sperm. The closer that an embryo is exposed to the threshold, the more the effect on the ensuing embryo will fail to reach various milestones, including blastocyst stage, implantation, pregnancy loss, an adverse delivery outcome, or offspring health. We also present a summary of the role that testicular sperm extraction may play in improving outcomes for couples in which the male has a high double-strand DNA break level in his sperm.

CONCLUSIONS

Double-strand DNA breaks in sperm provide a greater stress on repair mechanisms and challenge the threshold of repair in oocytes. It is therefore imperative that we improve our understanding and diagnostic ability of sperm DNA, and in particular, how double-strand DNA breaks originate and how an oocyte or embryo is able to deal with them.

Longitudinal semen parameter assessments and live birth: variability and implications for treatment strategies

OBJECTIVE

To examine whether semen parameters are associated with live birth among couples seeking infertility treatment after accounting for semen parameter variability.

DESIGN

Folic Acid and Zinc Supplementation Trial (FAZST) prospective cohort.

SETTING

Four US reproductive endocrinology and infertility care study centers, 2013-2017.

PATIENT(S)

Couples (n = 2,369) seeking fertility consultations at 4 US infertility care study centers.

INTERVENTION(S)

Semen volume, pH, sperm viability, morphology, progressive and total motility, concentration, count, and total and progressive motile count assessed at baseline and at 2, 4, and 6 months after enrollment.

MAIN OUTCOME MEASURE(S)

Log-binomial models stratified by fertility treatment received (in vitro fertilization [IVF], intrauterine insemination [IUI], ovulation induction [OI], or no treatment) estimated risk differences (RDs) between semen parameter quartiles and live birth and accounted for multiple semen assessments per person. We accounted for abstinence time, the biological interdependence of semen parameters, and potential selection bias because of loss to follow-up.

RESULT(S)

Among couples using OI only or no treatment, 39% had a live birth, and relative to the highest quartile, the lowest quartiles of morphology (RD, -19 [95% CI, -23 to -15] per 100 couples), motility (RD, -13 [95% CI, -17 to -9]), concentration (RD, -22 [95% CI, -26 to -19]), and total motile count (RD, -18 [95% CI, -22 to -14]) were associated with fewer live births. For IUI, 26% had a live birth, and the lowest quartiles of volume (RD, -6 [95% CI, -11 to -0.4]), concentration (RD, -6 [95% CI, -11 to -0.1]), count (RD, -10 [95% CI, -15 to -4]), and total motile count (RD, -7 [95% CI, -13 to -1]) were associated with fewer live births. For IVF, 61% had a live birth, and only morphology (Q1 RD, -7 [95% CI, -14 to 0.2]; Q2 RD, -10 [95% CI, -17 to -2.2]) was associated with live birth.

CONCLUSION(S)

Semen parameters are critical in couples undergoing OI/IUI. Only low morphology was important for live birth after IVF. Although data supporting the use of semen parameters are fragmented across differing populations, current findings are generalizable across the range of male fertility and couple fertility treatments, providing evidence about which semen parameters are most relevant in which settings.

CLINICAL TRIAL REGISTRATION NUMBER

NCT#01857310.

The effect of SSRIs on Semen quality: A systematic review and meta-analysis

Selective serotonin reuptake inhibitors (SSRIs) are widely used for a variety of diseases, and their impact on semen quality is unclear. We performed a systematic search in PubMed and Embase, and after a strict screening, we included 4 studies with a total of 222 male participants. In result, SSRIs reduced normal sperm morphology (95% CI [−16.29, −3.77], p = 0.002), sperm concentration (95%CI [−43.88, −4.18], p = 0.02), sperm motility (95%CI [−23.46, −0.47], p = 0.04) and sperm DNA fragmentation index (DFI) (95% CI [6.66,21.93], p = 0.0002), without a statistically significant effect on semen volume (95%CI [−0.75,0.65], p = 0.89). Moreover, the impact on both sperm morphology and sperm concentration were observed within the 3-month period of SSRIs use. In general, our meta-analysis showed that SSRIs have a negative effect on semen quality. More larger, randomized, well-controlled clinical studies should be conducted to support our conclusion.

Sperm DNA fragmentation negatively influences the cumulative live birth rate in the intracytoplasmic sperm injection cycles of couples with unexplained infertility

Objective: This study aimed to determine the effect of sperm DNA fragmentation (SDF) on the cumulative live birth rate (CLBR) in intracytoplasmic sperm injection (ICSI) cycles in couples with unexplained infertility.Methods: We conducted a prospective study of 145 couples who underwent ICSI cycles for unexplained infertility. Based on the SDF rate, patients were categorized into a low SDF group (SDF ≤30%, n=97) and a high SDF group (SDF >30%, n=48). SDF was assessed using the acridine orange test on density gradient centrifugation prepared samples. The CLBR was calculated as the first live birth event per woman per egg collection over 2 years.Results: The high SDF group (SDF >30%) showed a significantly lower CLBR (p<0.05) and a significantly higher miscarriage rate (p<0.05) than the low SDF group (SDF ≤30%). No significant difference was observed in the implantation and cumulative pregnancy rates between the two SDF groups. The total number of embryo transfers was stratified further into fresh and frozen embryo transfers. In the fresh embryo transfers, there were significant differences in the implantation rates, clinical pregnancy rates, and live birth rates (p<0.05) between the low SDF and high SDF groups. However, in the frozen embryo transfers, there were no significant differences in clinical outcomes between the two groups. In the multivariable logistic regression analysis, SDF was a predictor of CLBR (p<0.05) when adjusted for possible confounding factors.Conclusion: High SDF was associated with a lower CLBR and a higher miscarriage rate in the ICSI cycles of couples with unexplained infertility.

Correlation between serum levels of reproductive hormones and testicular spermatogenic function in men with azoospermia

To investigate the serum levels of reproductive hormones in men with azoospermia and explore the correlation between abnormal reproductive hormones and the results of testicular biopsy and seminiferous extraction. The serum levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone (T), and pituitary prolactin (PRL), were measured by Radio immunoassay. Testicular biopsy was used to determine whether patient's had spermatozoa. Spearman's correlation analysis was used to analyse the correlation between LH, FSH, testicular volume, and spermatogenic function. Receiver operator characteristic (ROC) curves were used to evaluate the efficacy and significance of LH and FSH for the detection of spermatozoa and copy number variation sequencing (CNV-seq). Compared with the control group, the serum levels of FSH and LH in the azoospermia group were significantly up-regulated (p < 0.001). Prolactin (PRL) and testosterone levels did not differ significantly between the two groups (p > 0.05). The serum levels of FSH and LH were negatively correlated with testicular spermatogenic function and testicular volume. The areas under the ROC curves for determining FSH and LH potency by testicular biopsy with or without spermatozoa were 0.640 and 0.622, respectively. The areas under the ROC curves for the potency of FSH and LH, as judged by CNV detection results, were 0.523 and 0.534, respectively. Serum levels of FSH and LH are associated with azoospermia and may be of predictive significance in the clinical setting for the acquisition of spermatozoa by testicular biopsy.

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.

The association between serum estradiol levels and sperm DNA integrity

In men from the general population, BMI has been associated with a lower sperm DNA fragmentation index (DFI). We wondered whether this could be due to estradiol, which is associated with BMI and reported important for sperm function. Our objective was to investigate the association between estradiol and DFI. In 2008-2010, we recruited 284 young men from the general population to deliver samples of semen and blood and answer questionnaires. Serum concentrations of reproductive hormones and DFI were analyzed, the latter using the Sperm Chromatin Structure Assay. Associations were studied using general linear models. The first model utilized metric values of estradiol, whereas the second model compared men with high and low levels, dichotomized by the median value. A possible interaction between estradiol and testosterone was also examined. When investigating metric estradiol levels and DFI, an inverse association was seen without adjustments (p = .02), but the statistical significance was lost at adjustments for potential confounders (p = .08). Men with lower estradiol levels (<88 pmol/L, mean 71 pmol/L) had a statistically significantly higher DFI than men with higher levels of estradiol (≥88 pmol/L, mean 110 pmol/L). Mean ratio difference was 1.21 (p = .002) without adjustments and 1.18 (p = .01) with adjustments. A statistically significant difference in DFI was observed in men with testosterone levels below median when comparing high and low estradiol (p < .001). This study supports the idea that serum estradiol levels are protective for sperm DNA integrity, at least at lower testosterone levels.

Evaluation of selected semen parameters and biomarkers of male infertility - preliminary study

Background: Because the etiopathogenesis of male infertility is multifactorial our study was designed to clarify the relationship between standard semen parameters, testicular volume, levels of reproductive hormones and the fragmentation of sperm nuclear DNA (SDF). Methods: Patients (n = 130) were clustered as subjects: 1) with an abnormal volume (utrasonography) of at least one testis (<12 mL) or with a normal volume of testes and 2) with abnormal levels of at least one of the reproductive hormones (FSH, LH, PRL, TSH, total T - electrochemiluminescence method) or with normal hormonal profiles and 3) with high level of SDF (>30%), moderate (>15-30%) or low (≤15%) (sperm chromatin dispersion test). Results: In subjects with a decreased testicular volume and in subjects with abnormal levels of reproductive hormones, decreased basic semen parameters were found. Participants with abnormal testicular volume had a higher percentage of SDF and a higher level of FSH (Mann-Whitney U test). In turn, men with a high level of SDF had lower testicular volume and conventional sperm parameters than men with a low level of SDF (Kruskal-Wallis test). Conclusions: We showed that spermatogenesis disorders coexisted with decreased testicular volume and increased FSH levels. The disorders of spermatogenesis were manifested by reduced basic sperm characteristics and a high level of sperm nuclear DNA damage.

Protamines and DNA integrity as a biomarkers of sperm quality and assisted conception outcome

Present research aim was to identify functional tests in semen associated with DNA damage and chromatin maturity (protamination) which predict the outcome in assisted reproduction. Couples were grouped according to male partner semen parameters, into normozoospermia (NZs), severe male factor (SMF) and mild male factor (MMF). DNA fragmentation index (DFI) in spermatozoa was analysed by sperms chromatin dispersion (SCD), sperm chromatin structure assay (SCSA) and acridine orange testing (AOT). Chromomycin A3 (CMA3) and toluidine blue (TB) staining to measure sperm chromatin maturity (CM). DFI and chromatin decondensation were significantly lower in N compared to male factor categories (MMF and SMF). Aneuploidy embryos were significantly higher in couples with male factor infertility (MMF and SMF). A positive correlation was observed between fertilization rate (FR) and live birth rate (LBR) with sperm concentration, motility, vitality, normal sperm morphology and negative correlation between sperm DFI and sperm CM. No correlation was observed between embryo aneuploidy and sperm DFI or CM. Lower percentage of spermatozoa chromatin integrity are associated with low fertilization and live birth rate. Male factor infertility, due to impaired semen parameters and chromatin defects could be regarded in future as an indication of IVF/ICSI, and predictor of assisted reproductive techniques outcome.

Exposure to polycyclic aromatic hydrocarbons and nicotine, and associations with sperm DNA fragmentation

Background

Tobacco smoking has been reported to cause DNA fragmentation and has been suggested to cause mutations in spermatozoa. These effects have been ascribed to the action of polycyclic aromatic hydrocarbons (PAH) present in the smoke. Simultaneously, DNA fragmentation has been associated with mutagenesis.

Objective

The aim of this study was to investigate whether levels of urinary biomarkers of PAH and nicotine exposure were associated with sperm DNA fragmentation.

Methods

In the urine of 381 men recruited from two cohorts of young men (17–21 years old) from the general Swedish population, the PAH metabolites 1‐hydroxypyrene and 2‐hydroxyphenanthrene, as well as the nicotine metabolite cotinine, were measured. The sperm DNA fragmentation index (DFI) was analysed using the sperm chromatin structure assay. Associations between the DFI, and PAH metabolite levels as continuous variables as well as in quartiles, were studied by general linear models adjusted for abstinence time. A similar analysis was carried out for cotinine levels, according to which the men were categorised as “non‐smoking” (n = 216) and “smoking” (n = 165).

Results

No association was found between levels of any of the three biomarkers and DFI, either as a continuous variable (p = 0.87–0.99), or when comparing the lowest and the highest quartiles (p = 0.11–0.61). The same was true for comparison of men categorised as non‐smoking or smoking (DFI 11.1% vs. 11.8%, p = 0.31).

Discussion

We found no evidence of PAH or nicotine exposure to be associated with DFI, which does not exclude that these exposures may have other effects on sperm DNA.

Conclusion

In these young men, levels of biomarkers of nicotine and PAH exposure were not associated with DFI.

The Effect of Sperm DNA Fragmentation on In Vitro Fertilization Outcomes for Women With Polycystic Ovary Syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is a prevalent endocrine disease in reproductive women associated with poor pregnancy outcomes. In modern society, people pay more attention to the female factor, but it is uncertain whether sperm quality is another factor affecting pregnancy outcomes of patients with PCOS.

METHOD

The effect of sperm DNA fragmentation (SDF) on oocyte fertilization, embryonic development, and pregnancy outcomes for patients with PCOS who underwent in vitro fertilization (IVF) treatment was studied. A total of 141 PCOS patients and 332 control patients undergoing IVF treatment were recruited from January 2017 to December 2019. All female patients were designated into two groups according to the Rotterdam criteria. Each group was divided into two sets, DNA fragmentation index (DFI) ≤15% and DFI > 15%, on the basis of sperm DFI.

RESULT

There were no differences in basic clinical characteristics between couples with a sperm DFI ≤ 15% or DFI > 15%. For control patients, no differences were observed in IVF outcomes. However, for PCOS patients, although there were no differences in the fertilization (60.4% vs. 59.9%, p = 0.831), high-quality embryo (68.5% vs. 67.9% p = 0.832), clinical pregnancy (78.4% vs. 66.7%, p = 0.148), and abortion (12.5% vs. 11.5%, p = 1.000) rates, a significantly lower high-quality blastocyst formation rate (26.3% vs. 16.3%, p = 0.023) was observed for couples with a sperm DFI > 15% compared with a sperm DFI ≤ 15%.

CONCLUSION

For PCOS patients undergoing IVF, oocytes fertilized using sperm with higher DFI led to a lower high-quality blastocyst formation rate but had no influence on fertilization, high-quality embryo, clinical pregnancy, and miscarriage rates.

Role of Female Age in Regulating the Effect of Sperm DNA Fragmentation on the Live Birth Rates in Intracytoplasmic Sperm Injection Cycles with Own and Donor Oocytes

Background

Sperm DNA integrity assessment has been progressively used as an unfettered measure of sperm as it proffers more prognostic and diagnostic information than routine semen analysis. The contentious effect of sperm DNA fragmentation (SDF) on clinical outcomes can be attributed to female factors such as age, oocyte quality and ovarian reserve.

Aims

The study is mainly aimed to know the influence of SDF on the live birth rates in intracytoplasmic sperm injection (ICSI) cycles with own and donor oocytes. Second, to know the role of female age in regulating the effect of SDF on the live birth rates in ICSI cycles with own and donor oocytes.

Setting and Design

A prospective cohort study was done at our tertiary care centre attached to the reproductive medicine unit in medical college.

Materials and Methods

The study included 356 patients who underwent first ICSI cycles either with own or donor-oocytes along with day 5 fresh embryo transfers only. The main outcome measures were live birth rates and miscarriage rates.

Statistical Analysis Used

Chi-squared test was used to compare the categorical variables between the groups. The receiver operating characteristic curve was developed to correlate the female age with the live birth rate.

Results

A significant decrease in the live birth rates (42.85% vs. 26.15%, P = 0.023) and an increase in the miscarriage rates (12.30% vs. 34.61%, P = 0.013) were observed in the high-SDF group ICSI cycles of own-oocyte patients. However, there was no significant difference in the live birth rates and miscarriage rates in the low- and high-SDF groups of donor oocyte ICSI cycle patients (P > 0.05). The own-oocyte ICSI cycle patients were further stratified based on the female age. In the female age group ≤30 years there was no significant difference in the live birth and miscarriage rates (P > 0.05) similar to donor oocyte ICSI cycles. Whereas, there was a significant difference in the live birth rates in the females of age >30 years (13.79% vs. 34.37%, P = 0.040).

Conclusion

In conclusion, high-SDF has a negative influence on the live birth rates and a positive influence on the miscarriage rates in patients with own-oocyte ICSI cycles. A similar influence was not observed in patients with donor-oocyte ICSI cycles and in young female patients (age ≤30 years) with own-oocyte ICSI cycles.

Correlation study of male semen parameters and embryo aneuploidy in preimplantation genetic testing for aneuploidy

OBJECTIVE

The purpose of this study was to evaluate the influence of abnormal semen parameters on embryo aneuploidy based on single nucleotide polymorphism microarray (SNP array).

METHODS

A total of 464 blastocysts from 103 PGT-A cycles were analyzed. The embryo quality and embryo aneuploidy rates were compared between different groups which divided by male semen parameters (sperm concentration, motility, morphology, and DFI) according the WHO criteria (2021).

RESULTS

The total blastocysts chromosome aneuploidy rate was 42.3% (191/452). In the teratozoospermia group, the good-quality embryo and blastocyst formation rate were lower than the normal group(44.4% vs 60.7%, P <0.01; 33.3% vs 43.5%, P <0.05), The good-quality embryo rate in normal DFI group was significantly higher than high-DFI group (59.0% vs 48.4%, P < 0.05). The blastocyst aneuploidy rate in low sperm concentration group, and high DFI group was no differences between with that in normal sperm concentration and DFI group (47.7% vs 37.8% and 44.7% vs 37.8%, P>0.05). The aneuploid rate of blastocyst in teratozoospermic and asthenozoospermia group was significantly higher than that of normal morphology and motility group (50.0% vs 34.0% and 46.7% vs 33.7%, P<0.05).

CONCLUSION

Our study revealed that sperm DFI were positively correlated with blastocyst aneuploidy rate, while sperm motility and sperm morphology rate were negatively correlated with blastocyst aneuploidy rate. Abnormal semen parameters may affect embryo quality and increase the aneuploidy rate of blastocyst chromosomes, suggesting that in clinical practice of assisted reproduction patients with abnormal semen parameters can be treated in advance to improve sperm quality, so as to reduce the impact on embryo quality and achieve a better pregnancy outcome.

Effect of varicocele on sperm DNA damage: A systematic review and meta-analysis

The updated meta-analysis was conducted to further verify the effect of varicocele on sperm DNA damage, supplying clinicians and researchers with high-grade evidence. The sperm DNA damage was evaluated by DNA fragmentation index (DFI), associated with the male fertility capability tightly. PubMed, Web of Science and Cochrane Library were searched extensively for eligible studies with the search terms: varicocele, sperm DNA and sperm DNA damage. Finally, a total of 12 studies were included in our meta-analysis with a total of 845 patients diagnosed with varicocele and 2,377 healthy controls. A statistical difference of DFI between varicocele patients and healthy controls was found after pooling the data ((Standardised mean difference) SMD: 1.40, 95%CI: 0.83-1.98, p < .0001), using the random effect model. We conducted subgroup analysis according to study region (Brazil and Other countries), detection methods of DFI (TUNEL, Comet, and SCSA), sample size (<50 and >50) and age (<30 and >30 years), based on substantial heterogeneity among eligible studies. The stability of pooled results was verified by sensitivity analysis. All these statistical analyses were conducted using Stata version 16.0. In conclusion, patients diagnosed with clinical varicocele had higher DFI than healthy controls, which means varicocele could impair sperm DNA, consequently the fertility potential of affected men.

Quantitative selection of single human sperm with high DNA integrity for intracytoplasmic sperm injection

OBJECTIVE

To study at the single-cell level whether a sperm's motility and morphology parameters reflect its DNA integrity, and to establish a set of quantitative criteria for selecting single sperm with high DNA integrity.

DESIGN

Prospective study.

SETTING

In vitro fertilization center and university laboratories.

PATIENT(S)

Male patients undergoing infertility treatments.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The motility and morphology parameters of each sperm were measured with the use of computer vision algorithms. The sperm was then aspirated and transferred for DNA fragmentation measurement by single-cell gel electrophoresis (comet assay).

RESULT(S)

We adapted the World Health Organization criteria, which were originally defined for semen analysis, and established a set of quantitative criteria for single-sperm selection in intracytoplasmic sperm injection. Sperm satisfying the criteria had significantly lower DNA fragmentation levels than the sample population. Both normal motility and normal morphology were required for a sperm to have low DNA fragmentation. The quantitative criteria were integrated into a software program for sperm selection. In blind tests in which our software and three embryologists selected sperm from the same patient samples, our software outperformed the embryologists and selected sperm with the highest DNA integrity.

CONCLUSION(S)

At the single-cell level, a sperm's motility and morphology parameters reflect its DNA integrity. The developed technique and criteria hold the potential to mitigate the risk factor of sperm DNA fragmentation in intracytoplasmic sperm injection.

Implementation of an in-house flow cytometric analysis of DNA fragmentation in spermatozoa

An increased amount of DNA fragmentation in the spermatozoa (SDF) is linked to male infertility. The Sperm Chromatin Structure Assay (SCSA) is widely used for analysis of SDF. However, the current software (SCSASoft^®) linked to this assay is licensed and often located within larger diagnostic centers. In this study, we present a protocol for using other types of software than SCSASoft^® to determine the SDF index (DFI) with clinical relevance. This protocol is engineered after collecting and analyzing 254 samples from fertility patients and sperm donors over a 15-month period. DFI is analyzed using a strict protocol where the spermatozoa are treated with a strong acid (pH 1.2) followed by acridine orange. DFI is determined by a standard flow cytometric software, FACSDiva 6.1.3. Analysis of the outcome of the fertility treatment is included for 137 patients receiving either intrauterine inseminations (IUI) or timed coitus (TC). The results show that the chance of pregnancy declines as DFI increases. We also found that the male DFI affects the chance of pregnancy independent of the female age. We have shown that a standard flow cytometric software can be used when determining a clinical relevant DFI. These findings are a significant step toward implementing the analysis as a part of the routine, in-house diagnosing of the male fertility patient and subsequently optimizing the treatment course of the couple with reduced human and financial costs.

DNA fragmentation of sperm: a radical examination of the contribution of oxidative stress and age in 16 945 semen samples

STUDY QUESTION

What is the relationship between sperm DNA fragmentation and oxidative stress (OS) with increasing male age?

SUMMARY ANSWER

Sperm DNA fragmentation increases with age and is likely related to both defective spermatogenesis and increasing OS levels.

WHAT IS KNOWN ALREADY

Sperm quality declines with age. The presence of DNA damage in a high fraction of spermatozoa from a raw semen sample is associated with lower male fertility in natural conception and intrauterine insemination.

STUDY DESIGN, SIZE, DURATION

A retrospective cohort study of 16 945 semen samples analysed at a single reference laboratory between January 2010 and December 2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All males were undergoing an infertility evaluation. The cohort was divided into seven age categories: <30, 30-34, 35-39, 40-44, 45-49, 50 to <54 and ≥55 years. The mean age was 37.6 years (SD 6.8). Sperm DNA fragmentation index (DFI) and high DNA stainability (HDS) were calculated using flow cytometry. OS levels were measured using the oxidative stress adducts (OSA) test, by spectrophotometry. ANOVA with weighted polynomial contrast analysis was used to evaluate trends for DFI, OSA and HDS values across age categories.

MAIN RESULTS AND THE ROLE OF CHANCE

Mean DFI significantly increased across all age groups (Ptrend < 0.001). OSA was lowest in patients <30 years old (mean 3.6, SD 1.0) and also increased as age increased (Ptrend < 0.001). There was a statistically significant difference between age groups for each of the three parameters (P < 0.001). There was a significant linear trend for DFI, OSA and HDS across the seven age categories (P < 0.001). Among patients with high DFI, there was a decreasing age-dependent trend in the patients observed with high OSA (P < 0.001).

LIMITATIONS, REASONS FOR CAUTION

This is a retrospective study. All males included in the study were undergoing a work-up for infertility and may not be representative of a fertile population. Additional patient demographics and clinical data were not available.

WIDER IMPLICATIONS OF THE FINDINGS

DNA and/or oxidative damage in sperm may be just as important to understand as the chromosomal aberrations that are carried in the oocyte. Further studies are needed to evaluate the effect of advancing paternal age on the male genome and, ultimately, on the health of the offspring.

STUDY FUNDING/COMPETING INTEREST(S)

No funding was obtained for this study. V.D. is an employee of Reprosource/Quest Diagnostics. D.S. reports he was a Scientific Advisor to Cooper Surgical.

TRIAL REGISTRATION NUMBER

N/A.

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.

Negative Impact of Elevated DNA Fragmentation and Human Papillomavirus (HPV) Presence in Sperm on the Outcome of Intra-Uterine Insemination (IUI)

We wanted to determine the sperm DNA fragmentation index (DFI) cutoff for clinical pregnancies in women receiving intra-uterine insemination (IUI) with this sperm and to assess the contribution of Human Papillomavirus (HPV) infection on sperm DNA damage and its impact on clinical pregnancies. Prospective non-interventional multi-center study with 161 infertile couples going through 209 cycles of IUI in hospital fertility centers in Flanders, Belgium. Measurement of DFI and HPV DNA with type specific quantitative PCRs (HPV 6, 11, 16, 18, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66 and 68) in sperm before its use in IUI. Clinical pregnancy (CP) rate was used as the outcome to analyze the impact on fertility outcome and to calculated the clinical cutoff value for DFI. A DFI criterion value of 26% was obtained by receiver operating characteristic (ROC) curve analysis. Couples with a male DFI > 26% had significantly less CPs than couples with DFI below 26% (OR 0.0326; 95% CI 0.0019 to 0.5400; p = 0.017). In sperm, HPV prevalence was 14.8%/IUI cycle. Sperm samples containing HPV had a significantly higher DFI compared to HPV negative sperm samples (29.8% vs. 20.9%; p = 0.011). When HPV-virions were present in sperm, no clinical pregnancies were observed. More than 1 in 5 of samples with normal semen parameters (17/78; 21.8%) had an elevated DFI or was HPV positive. Sperm DFI is a robust predictor of clinical pregnancies in women receiving IUI with this sperm. When DFI exceeds 26%, clinical pregnancies are less likely and in vitro fertilization techniques should be considered.

Lack of trusted diagnostic tools for undetermined male infertility

Semen analysis is the cornerstone of evaluating male infertility, but it is imperfect and insufficient to diagnose male infertility. As a result, about 20% of infertile males have undetermined infertility, a term encompassing male infertility with an unknown underlying cause. Undetermined male infertility includes two categories: (i) idiopathic male infertility-infertile males with abnormal semen analyses with an unknown cause for that abnormality and (ii) unexplained male infertility-males with "normal" semen analyses who are unable to impregnate due to unknown causes. The treatment of males with undetermined infertility is limited due to a lack of understanding the frequency of general sperm defects (e.g., number, motility, shape, viability). Furthermore, there is a lack of trusted, quantitative, and predictive diagnostic tests that look inside the sperm to quantify defects such as DNA damage, RNA abnormalities, centriole dysfunction, or reactive oxygen species to discover the underlying cause. To better treat undetermined male infertility, further research is needed on the frequency of sperm defects and reliable diagnostic tools that assess intracellular sperm components must be developed. The purpose of this review is to uniquely create a paradigm of thought regarding categories of male infertility based on intracellular and extracellular features of semen and sperm, explore the prevalence of the various categories of male factor infertility, call attention to the lack of standardization and universal application of advanced sperm testing techniques beyond semen analysis, and clarify the limitations of standard semen analysis. We also call attention to the variability in definitions and consider the benefits towards undetermined male infertility if these gaps in research are filled.

X chromosome variants are associated with male fertility traits in two bovine populations

BACKGROUND

Twenty-five phenotypes were measured as indicators of bull fertility (1099 Brahman and 1719 Tropical Composite bulls). Measurements included sperm morphology, scrotal circumference, and sperm chromatin phenotypes such as DNA fragmentation and protamine deficiency. We estimated the heritability of these phenotypes and carried out genome-wide association studies (GWAS) within breed, using the bovine high-density chip, to detect quantitative trait loci (QTL).

RESULTS

Our analyses suggested that both sperm DNA fragmentation and sperm protamine deficiency are heritable (h2 from 0.10 to 0.22). To confirm these first estimates of heritability, further studies on sperm chromatin traits, with larger datasets are necessary. Our GWAS identified 12 QTL for bull fertility traits, based on at least five polymorphisms (P < 10-8) for each QTL. Five QTL were identified in Brahman and another seven in Tropical Composite bulls. Most of the significant polymorphisms detected in both breeds and nine of the 12 QTL were on chromosome X. The QTL were breed-specific, but for some traits, a closer inspection of the GWAS results revealed suggestive single nucleotide polymorphism (SNP) associations (P < 10-7) in both breeds. For example, the QTL for inhibin level in Braham could be relevant to Tropical Composites too (many polymorphisms reached P < 10-7 in the same region). The QTL for sperm midpiece morphological abnormalities on chromosome X (QTL peak at 4.92 Mb, P < 10-17) is an example of a breed-specific QTL, supported by 143 significant SNPs (P < 10-8) in Brahman, but absent in Tropical Composites. Our GWAS results add evidence to the mammalian specialization of the X chromosome, which during evolution has accumulated genes linked to spermatogenesis. Some of the polymorphisms on chromosome X were associated to more than one genetically correlated trait (correlations ranged from 0.33 to 0.51). Correlations and shared polymorphism associations support the hypothesis that these phenotypes share the same underlying cause, i.e. defective spermatogenesis.

CONCLUSIONS

Genetic improvement for bull fertility is possible through genomic selection, which is likely more accurate if the QTL on chromosome X are considered in the predictions. Polymorphisms associated with male fertility accumulate on this chromosome in cattle, as in humans and mice, suggesting its specialization.

Differences in sperm functionality and intracellular metabolites in Norwegian Red bulls of contrasting fertility

In the dairy breeding industry, prediction of bull fertility in artificial insemination (AI) is important for efficient and economically sustainable production. However, it is challenging to identify bulls with superior fertility applying conventional in vitro sperm assays. In the present study, sperm functionality was investigated to identify a multivariate model that could predict fertility. Two groups of young Norwegian Red bulls were selected, one with inferior fertility (18 bulls) and one with superior fertility (19 bulls) based on non-return rate after 56 days (NR56). Frozen-thawed semen doses were analysed for sperm chromatin integrity, viability, acrosome integrity, motility, and ATP content. A targeted approach was used to study intracellular concentrations of amino acids and trace elements in viable sperm cells. Significant differences between the two groups of bulls were observed, both for sperm functional attributes and intracellular concentrations of metabolites. Pearson correlation analyses indicated a negative relationship between NR56 and chromatin integrity parameters, DNA fragmentation index (DFI) and high DNA stainability (HDS). Several motility parameters correlated positively with NR56. The concentrations of cysteine and glutamic acid in sperm cells correlated negatively with NR56, while the concentrations of aspartic acid, leucine and serine showed a positive NR56-correlation. The sperm intracellular concentrations of the trace elements Fe, Al and Zn, correlated negatively with NR56. Correlations were observed between several sperm parameters and metabolites. Stepwise multiple regression analysis indicated that the best predictor of NR56 was a model containing %DFI, together with the intracellular sperm concentration of aspartic acid, Fe and Zn. This model explained 59% of the variability in NR56.

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.

Sperm DNA Integrity and Male Fertility in Farm Animals: A Review

The accurate prediction of male fertility is of major economic importance in the animal breeding industry. However, the results of conventional semen analysis do not always correlate with field fertility outcomes. There is evidence to indicate that mammalian fertilization and subsequent embryo development depend, in part, on the inherent integrity of the sperm DNA. Understanding the complex packaging of mammalian sperm chromatin and assessment of DNA integrity could potentially provide a benchmark in clinical infertility. In the era of assisted reproduction, especially when in-vitro fertilization or gamete intrafallopian transfer or intracytoplasmic sperm injection is used, assessment of sperm DNA integrity is important because spermatozoa are not subjected to the selection process occurring naturally in the female reproductive tract. Although sperm DNA integrity testing measures a significant biological parameter, its precise role in the infertility evaluation in farm animals remains unclear. In this review, the earlier findings on sperm DNA integrity in relation to male fertility are compiled and analyzed. Furthermore, the causes and consequences of sperm DNA damage are described, together with a review of advances in methods for detection of sperm DNA damage, and the prognostic value of sperm DNA quality on male fertility.

Fractalkine and apoptotic/anti-apoptotic markers in granulosa cells of women with polycystic ovarian syndrome

Owing to the role of fractalkine in regulating cellular apoptosis/proliferation, we investigated fractalkine effects on apoptosis/proliferation signaling of granulosa cells in polycystic ovarian syndrome (PCOS) patients through in vitro and in vivo experiments. In vivo, granulosa cells were collected from 40 women undergoing oocyte retrieval (20 controls and 20 PCOS). The expression levels of fractalkine, BAX, Bcl2, Bcl2-XL, Bad, and TNF-α were assessed using RT-PCR. In vitro, we determined the effect of different doses of fractalkine on the expression of the above mentioned genes in GCs of both groups. We found that the expression levels of fractalkine and Bcl-2 were significantly lower in the GCs of PCOS patients compared to the control group (p < 0.05). In contrast, the expression levels of TNF-α and BAX were higher in the patient's group than in the control group. The results suggested that expression levels of fractalkine were negatively and positively correlated with the number of oocytes and fertilized oocytes respectively. Moreover, fractalkine could dose-dependently increase fractalkine and decrease BAD, BAX, Bcl-xl, and TNF-α expressions in the control GCs. In contrast, GCs collected from PCOS patients revealed an increase in expression of BAD, BAX, and Bcl-xl following fractalkine treatment. Our findings indicated that insufficient expression of fractalkine in PCOS patients is related with elevated apoptotic and inflammatory markers and reduced anti-apoptotic genes in the GCs.

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.

Assessment of DNA Susceptibility to Denaturation as a Marker of Chromatin Structure

The susceptibility of DNA in situ to denaturation is modulated by its interactions with histone and nonhistone proteins, as well as with other chromatin components related to the maintenance of the 3D nuclear structure. Measurement of DNA proclivity to denature by cytometry provides insight into chromatin structure and thus can be used to recognize cells in different phases of the cell cycle, including mitosis, quiescence (G₀ ), and apoptosis, as well as to identify the effects of drugs that modify chromatin structure. Particularly useful is the method's ability to detect chromatin changes in sperm cells related to DNA fragmentation and infertility. This article presents a flow cytometric procedure for assessing DNA denaturation based on application of the metachromatic property of acridine orange (AO) to differentially stain single- versus double-stranded DNA. This approach circumvents limitations of biochemical methods of examining DNA denaturation, in particular the fact that the latter destroy higher orders of chromatin structure and that, being applied to bulk cell populations, they cannot detect heterogeneity of individual cells. Because the metachromatic properties of AO have also found application in other cytometric procedures, such as differential staining of RNA versus DNA and assessment of lysosomal proton pump including autophagy, to avert confusion between these approaches and the use of this dye in the DNA denaturation assay, these AO applications are briefly outlined in this unit as well. © 2019 by John Wiley & Sons, Inc. Basic Protocol: Differential staining of single- versus double-stranded DNA with acridine orange.

The effect of sperm DNA fragmentation index on assisted reproductive technology outcomes and its relationship with semen parameters and lifestyle

Background

The sperm DNA fragmentation index (DFI) is widely regarded as a key measure for assessing male fertility, but the predictive value of the DFI for outcomes of assisted reproductive technology (ART) remains under debate. In this study, we used a large sample to analyze the effect of sperm DFI on pregnancy outcomes following ART and its relationship with oocyte fertilization and embryo development in in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI). We also explore the value of sperm DNA fragmentation (SDF) and its associated factors in assessing male fertility.

Methods

The relationship between the DFI measured with the sperm chromatin structure assay (SCSA) and pregnancy outcomes following ART were retrospectively analyzed in 2,622 ART treatment cycles, of which 1,185 were intrauterine insemination (IUI) cycles, 1,221 were IVF cycles and 216 were ICSI cycles. Rates of pregnancy, early abortion, oocyte fertilization and good quality embryos from IVF and ICSI cycles were compared between the groups of low DFI (DFI ≤15%), medium DFI (15%< DFI <30%) and high DFI (DFI ≥30%). Additionally, the relationships between sperm DFI and male lifestyle variables such as age, body mass index, smoking, and alcohol consumption, as well as routine semen parameters, were analyzed.

Results

Clinical pregnancy rates following IUI among high, medium, and low sperm DFI groups were 12.5% (11/88), 14.3% (48/336), and 13.4% (102/761), respectively, with no statistical difference between the groups (P=0.88); however, early abortion rates among these groups were 27.3% (3/11), 14.6% (7/48), and 4.9% (5/102), respectively, and the difference was statistically significant (P=0.02). No significant differences in the rates of clinical pregnancy, early abortion, oocyte fertilization, or good quality embryos in IVF or ICSI cycles were detected among different DFI groups (P<0.05). Sperm DFI was negatively associated with sperm density, vitality and normal morphology; It was positively correlated with age, abstinence time and unhealthy lifestyles.

Conclusions

As an increasingly common technique for reproductive testing, sperm DFI has proven to be very valuable in male fertility evaluation, but its significance as a predictor of pregnancy outcomes following ART requires further investigation.

Sperm DNA fragmentation is correlated with poor embryo development, lower implantation rate, and higher miscarriage rate in reproductive cycles of non-male factor infertility

OBJECTIVE

To study the implications of sperm DNA fragmentation (SDF) in intracytoplasmic sperm injection cycles for non-male factor infertility.

DESIGN

Prospective cohort study.

SETTING

Private university-affiliated IVF center.

PATIENT(S)

Data from 475 cycles performed from June 2016 to June 2017.

INTERVENTION(S)

Cycles were divided according to SDF rate into two groups: <30% SDF (n = 433) and ≥30% SDF (n = 42). Laboratory and clinical outcomes were compared between groups by generalized linear models adjusted for potential confounders.

MAIN OUTCOME MEASURE(S)

Embryo quality and miscarriage rates.

RESULT(S)

Fertilization rate was similar between groups (≥30% SDF, 85.28% ± 1.06% vs. <30% SDF, 90.68% ± 3.61%). Significantly lower rates of normal cleavage speed (≥30% SDF, 61.12% ± 4.21% vs. <30% SDF, 72.53% ± 1.24%), high-quality embryos at day 3 (≥30% SDF, 23.07% ± 5.56% vs. <30% SDF, 36.41% ± 1.53%), blastocyst formation (≥30% SDF, 39.09% ± 2.73% vs. <30% SDF, 58.83% ± 7.59%), blastocyst quality (≥30% SDF, 11.97% ± 1.22% vs. <30% SDF, 30.09% ± 2.39%), and implantation (33.24% ± 1.66% vs. <30% SDF, 46.40% ± 4.61%) were observed in cycles with higher SDF, despite similar pregnancy rates (≥30% SDF, 30.40% vs. <30% SDF, 32.40%). A 2.5-fold miscarriage rate was observed in cycles with an SDF above the established cutoff (≥30% SDF, 42.8% vs. <30% SDF, 16.8%).

CONCLUSION(S)

Higher SDF is correlated with poor embryo development, lower implantation rate, and higher miscarriage rate in non-male factor infertility intracytoplasmic sperm injection cycles. Since defects in sperm may be hidden, the SDF test can bring additional information to the sperm quality evaluation of men with unknown infertility history.

Utility and Predictive Value of Human Standard Semen Parameters and Sperm DNA Dispersion for Fertility Potential

Because the assessment of sperm DNA fragmentation (SDF) plays a key role in male fertility, our study was designed to find the relationships between SDF and standard semen parameters. The receiver operating characteristic (ROC) curve showed that 18% SDF is a prognostic parameter for discriminating between men with normal and abnormal standard semen parameters (n = 667). Men with > 18% SDF had significantly lower quality semen, a higher prevalence of abnormal semen characteristics, and a higher odds ratio for abnormal semen parameters compared to men with ≤ 18% SDF. An ROC analysis provided predictive values for age and semen parameters to distinguish between men with SDF > 18% and men with ≤ 18% SDF. SDF was positively correlated with male age and teratozoospermia index but negatively with sperm concentration, total number of spermatozoa, sperm morphology, progressive motility, and vitality. Our study shows that 18% SDF has a predictive value for distinguishing between men with normal and abnormal semen characteristics. Men with >18% SDF have a higher risk for abnormal semen parameters, while age and obtained semen parameters have a predictive value for SDF. There is a relationship between SDF and conventional sperm characteristics, and thus, SDF can be incorporated into male fertility assessment.

Sperm DNA fragmentation valued by SCSA and its correlation with conventional sperm parameters in male partner of recurrent spontaneous abortion couple

The objective of this study is to evaluate the predictive value of sperm DNA fragmentation Index (DFI) in unexplained recurrent spontaneous abortion (RSA) and to investigate its correlation with conventional sperm parameters. Besides, we aimed to reveal the necessity of establishing a DFI clinical threshold of each laboratory for the prognostic diagnosis of RSA and establish our own DFI threshold. Semen samples were collected from male partners of RSA patients (n = 139) and healthy recent fathers (control, n = 200). DFI was tested using SCSA and conventional semen analysis was performed using an automatic semen analyzer. The DFI value and distribution were compared between the two groups using corresponding statistical software. The diagnostic threshold value was established by ROC curve. The correlation between DFI and the conventional semen parameters of the 139 cases was further analyzed using Student's t test and Mann-Whitney U test. Our result showed that DFI was significantly higher in RSA patients compared with normal donor controls. We established our own DFI threshold at 13.59%. There was only a weak partial correlation between DFI values and conventional sperm analysis parameters. Our present study suggested that DFI might be used as a valuable predictor for RSA independent of conventional sperm parameters. Additionally, we recommend that each laboratory should establish its own clinical DFI threshold for more precise prediction of RSA and we recommend that sperm DNA fragmentation test should be included in complete sperm quality assessment in addition to conventional semen analysis for RSA male partners.

Association between semen parameters and chance of fatherhood - a long-term follow-up study

BACKGROUND

Evaluation of male fertility includes standard semen analysis; however, there is uncertainty about the value of sperm parameters in predicting fertility.

OBJECTIVE

To evaluate the association between semen parameters and fatherhood during a long-time period.

MATERIALS AND METHODS

Semen parameters (total sperm count, concentration, motility, and morphology) and sperm DNA fragmentation Index (DFI) assessed on samples collected from 195 Norwegian men from the general population in 2001/2002 were matched with information about fatherhood until 2015, obtained from the Medical Birth Register. The parameters were dichotomized as normal vs. abnormal according to the WHO reference values from 1999 and 2010. Cut-offs at 20% and 30% were used for DFI.

RESULTS

Among men who had no children before 2003, those with normal progressive sperm motility had more often become fathers (WHO 1999, cut-off ≥50%, adjusted OR 2.8, 95% CI 1.3-6.1 and WHO 2010, cut-off ≥32%; aOR 4.2, 95% CI 1.1-15). Based on the WHO 1999 reference value, men with normal sperm concentration (≥20 × 10⁶ /mL) had more often become fathers (aOR 3.1, 95% CI 1.1-8.6). Men with progressive sperm motility ≥50% and concentration ≥20 × 10⁶ /mL did more often achieve fatherhood (aOR 8.4, 95% CI 2.1-34). For DFI, there was a borderline significance at cut-off 20% in the group of men who had ever been fathers (OR 2.7, 95% CI 1.0-7.0 p < 0.05).

DISCUSSION

The results indicate that sperm progressive motility, sperm concentration, and DFI are associated with fatherhood during a longer time period, with sperm motility being most consistent. Although the sample size is relatively small and our results should be replicated in larger studies, they may be of clinical relevance.

CONCLUSION

Semen parameters may have a diagnostic value not only in a short time frame but also for predicting future fertility potential.

Integration of sperm DNA damage assessment into OECD test guidelines for genotoxicity testing using the MutaMouse model

The Organisation for Economic Co-operation and Development (OECD) endorses test guidelines (TG) for identifying chemicals that are genotoxic, such as the transgenic rodent gene mutation assay (TG 488). Current OECD TG do not include assays for sperm DNA damage resulting in a critical testing gap. We evaluated the performance of the Sperm Chromatin Structure Assay (SCSA) and the Terminal Deoxynucleotidyl Transferase-Mediated Deoxyuridine Triphosphate Nick end Labeling (TUNEL) assay to detect sperm DNA damage within the recommended TG 488 protocol. MutaMouse males received 0, 0.5, 1, or 2 mg/kg/day triethylenemelamine (TEM), a multifunctional alkylating agent, for 28 days orally and tissues were collected two (blood) and three (sperm and bone marrow) days later. TEM significantly increased the frequency of lacZ mutants in bone marrow, and of micronuclei (MN) in both reticulocytes (%MN-RET) and normochromatic erythrocytes (%MN-NCE) in a dose-dependent manner (P < 0.05). The percentage of DNA fragmentation index (%DFI) and %TUNEL positive cells demonstrated dose-related increases in sperm (P < 0.05), and the two assay results were strongly correlated (R = 0.9298). Within the same animal, a good correlation was observed between %MN-NCE and %DFI (R = 0.7189). Finally, benchmark dose modelling (BMD) showed comparable BMD₁₀ values among the somatic and germ cell assays. Our results suggest that sperm DNA damage assays can be easily integrated into standard OECD designs investigating genotoxicity in somatic tissues to provide key information on whether a chemical is genotoxic in germ cells and impact its risk assessment.

The male contribution to recurrent pregnancy loss

There are several known causes of recurrent pregnancy loss (RPL) in a couple, which include endocrine abnormalities, immunologic abnormalities, structural uterine abnormalities and karyotype abnormalities. The evaluation largely focuses on the female. The male contribution to RPL remains understudied. With the exception of the karyotype analysis, there is currently no other recommended testing for the male partner of a woman who has suffered multiple pregnancy losses. Chromosomal abnormalities are well defined causes of pregnancy losses in the literature. However, despite the fact that abnormal DNA fragmentation has been implicated in the pathogenesis of unexplained RPL, it is not routinely checked during the evaluation of RPL. This is likely due to the fact that abnormal DNA fragmentation is the end result of multiple different mechanisms including environmental exposures, varicoceles, gene alteration and epigenetic changes resulting in an inherent susceptibility to DNA damage? We are just beginning to scratch the surface of our understanding of the male contribution to RPL and more studies especially focusing on epigenetic modifications and gene alterations are needed.

Impact of a gestational exposure to diesel exhaust on offspring gonadal development: experimental study in the rabbit

The aim of the present work was to address experimentally the possible impact of exposure to air pollution during gestation on the differentiation and function of the gonads of the offspring using a rabbit model. Rabbits were exposed daily to diluted diesel exhaust gas or filtered air from the 3rd until the 27th day of gestation, during which time germ cells migrate in genital ridges and divide, and fetal sex is determined. Offspring gonads were collected shortly before birth (28th day of gestation) or after puberty (7.5 months after birth). The structure of the gonads was analyzed by histological and immunohistological methods. Serum concentrations of testosterone and anti-Müllerian hormone were determined using ELISA. The morphology and the endocrine function of the gonads collected just at the arrest of the exposure were similar in polluted and control animals in both sexes. No differences were observed as well in gonads collected after puberty. Sperm was collected at the head of the epididymis in adults. Sperm motility and DNA fragmentation were measured. Among all parameters analyzed, only the sperm DNA fragmentation rate was increased three-fold in exposed males. Mechanisms responsible for these modifications and their physiological consequences are to be further clarified.

Analysis on the association between sperm DNA fragmentation index and conventional semen parameters, blood microelements and seminal plasma ROS in male patients with infertility

We conducted this study to analyze the sperm DNA fragmentation index, conventional semen parameters, blood microelements and seminal plasma reactive oxygen species (ROS) in patients with male infertility to determine the association between each of the above male physiological parameters and DNA fragmentation index and infertility. Eighty cases of infertile males and 20 cases of normal males with children were divided into the infertility and control groups, respectively. Sperm DNA fragmentation index, conventional semen parameters, serum microelement content and seminal plasma ROS levels were detected, and the existing correlation between sperm DNA fragmentation index and the various physiological parameters were studied. The sperm DNA fragmentation index had no correlation with conventional sperm parameters. Our results demonstrated that zinc, lead and magnesium ions in the serum microelements were correlated with sperm DNA fragmentation (p<0.05). Upon an increase in zinc and lead serum concentration, there was a subsequent increase in sperm DNA fragmentation (p=0.008). Furthermore, when magnesium ion increased, it also caused an increase in sperm DNA fragmentation (p<0.05). The seminal plasma ROS of infertile males was higher than that of males with children (p<0.05). Our results suggest that sperm DNA fragmentation index is closely associated with the infertility rate and microelements of serum and seminal plasma ROS can impact the formation of sperm DNA fragmentation. Therefore, the sperm DNA fragmentation index can serve as an important parameter to assess male infertility.

In vitro study evaluating the instantaneous treatment of ozonised olive oil on human sperm

OBJECTIVE

The aim of our study was to evaluate the effects of ozonised olive oil (OOO) on human sperm in vitro.

METHODS

Human sperm was incubated with OOO for 20 s in vitro. The lowest concentration that completely immobilised all the sperm in 20 s without subsequent recovery of motility was recorded as the minimum effective concentration (MEC). The effects of OOO at MEC on human sperm viability, mitochondrial and acrosomal status, DNA integrity and transmission electron microscopy were observed.

RESULTS

Our findings demonstrate that OOO dose-dependently inhibits sperm motility. The MEC of OOO for 100% sperm immobilisation in 20 s was 6 μg/ml. Further experiments showed that sperm ultrastructure, function and DNA integrity were significantly affected after treatment with 6 μg/ml OOO in vitro.

CONCLUSIONS

OOO has spermicidal potential and may be explored as a promising vaginal contraceptive agent.