Chromatin condensation and DNA damage of human epididymal spermatozoa in obstructive azoospermia

Sperm degradation after vasectomy follows a sperm chromatin fragmentation dependent mechanism causing DNA breaks in the toroid linker regions

Vasectomy is a widely used surgical technique creating an obstructive azoospermia. Although sperm cannot be ejaculated, the testis maintains sperm production in vasectomized males. The continuous accumulation of sperm deposited in the epididymis and the vas deferens fraction necessarily need to be degraded and eliminated. While the elimination process is carried out by granulomas that form after vasectomy, the detailed mechanisms of sperm degradation are still not known. The aim was to assess whether sperm chromatin fragmentation (SCF), a mechanism that degrades the entire sperm genome at the toroid linker regions (TLRs), is activated after vasectomy in sperm cells. We vasectomized mice and evaluated the presence of TLR-specific double-strand breaks through pulsed-field gel electrophoresis and the Comet assay at 1, 2 and 3 weeks after surgery. Results for DNA damage (Olive tail moment) at single-cell level showed an increase of double-strand breaks after vasectomy for vas deferens sperm after 1, 2 and 3 weeks postvasectomy (21.78 ± 2.29; 19.71 ± 1.79 and 32.59 ± 1.81, respectively), compared to mock surgery (7.04 ± 1.03; 10.10 ± 1.29 and 8.64 ± 0.85, respectively; P < 0.001). Similar findings were obtained for cauda epididymis sperm (P < 0.001), but not for caput epididymis (P > 0.05). Pulsed-field gel electrophoresis showed the presence of double-stranded breaks between 15 and 145 kb, indicating that DNA breaks were produced mainly in the sperm TLRs. Results presented here suggest that SCF is a mechanism activated in vas deferens after vasectomy to degrade sperm DNA when they cannot be ejaculated, preventing their function.

Sperm characteristics in normal and abnormal ejaculates are differently influenced by length of ejaculatory abstinence

BACKGROUND

No association between the length of ejaculatory abstinence (LEA) and semen characteristics has been confirmed. A short LEA has been linked to improved sperm characteristics and a higher pregnancy rate, but its negative influence on sperm chromatin maturity and longevity may adversely affect reproductive outcomes.

OBJECTIVES

We sought to determine the influence of LEA on: (i) semen parameters in normozoospermic and abnormal ejaculates; and (ii) the outcomes of sperm-preparation methods in a large number of sub-fertile men undergoing infertility workups.

MATERIALS AND METHODS

This retrospective registry-based cohort study analyzed the data of 10,674 ejaculates from 7,972 sub-fertile men, who were then segregated into normozoospermic, oligozoospermic, asthenozoospermic, and oligo-asthenozoospermic cohorts. Variations in semen characteristics and post-wash outcomes were studied between 4 LEA intervals across 0-15 days.

RESULTS

An age-adjusted analysis of covariance (ANCOVA) model linked significant increases in ejaculate volume, sperm concentration (except in the oligozoospermic cohort), and total sperm number to an increased LEA (p < 0.05). LEA was negatively associated with motility (except in the asthenozoospermic cohort) and vitality (p < 0.05). Large-headed spermatozoa were less common with an increased LEA only in the oligoasthenozoopermic cohort (p < 0.05). In the normozoospermic cohort, a longer LEA led to fewer sperm with amorphous heads but more sperm with tapered heads and cytoplasmic droplets (p < 0.05). LEA extension resulted in greater sperm DNA fragmentation in the abnormal cohort (p < 0.01). The post-wash sperm concentration and total motile sperm count were significantly improved with a longer LEA in the normozoopsermic cohort (p < 0.05).

DISCUSSION AND CONCLUSION

Considering the findings in this study and existing literature, a generalized recommendation for long LEA has no clinical value. The LEA should be individualized based on the ejaculate profile and the need for specific clinical intervention. This article is protected by copyright. All rights reserved.

Congenital Bilateral Absence of the Vas Deferens

Congenital bilateral absence of the vas deferens (CBAVD) is clinically characterized by the absence of the bilateral vas deferens; the main clinical manifestation is infertility, accounting for 1–2% of male infertility cases. CBAVD may be accompanied by congenital abnormalities in the urogenital system and cystic fibrosis (CF)-related clinical manifestations. CBAVD can develop as a mild manifestation of CF or can be isolated. The main pathogenic mechanism of CBAVD is gene mutation, and CBAVD and CF have a common genetic mutation background. CFTR mutation is the main pathogenic cause of CBAVD and CF, and ADGRG2 mutation is the second most common cause. Although lack of the vas deferens in CBAVD patients causes infertility due to the inability to release sperm, the testes of CBAVD patients have spermatogenic function. Therefore, CBAVD patients can achieve fertility through sperm retrieval surgery and assisted reproductive technology (ART). However, gene mutations in CBAVD patients can have an impact on the ART outcome, and there is a risk of passing on gene mutations to offspring. For CBAVD patients and their spouses, performing genetic counseling (which currently refers mainly to CFTR mutation screening) helps to reduce the risks of genetic mutations being passed on to offspring and of offspring having CF with concomitant CBAVD.

High fat diet-induced obesity prolongs critical stages of the spermatogenic cycle in a Ldlr-/-.Leiden mouse model

Obesity can disturb spermatogenesis and subsequently affect male fertility and reproduction. In our study, we aim to elucidate at which cellular level of adult spermatogenesis the detrimental effects of obesity manifest. We induced high fat diet (HFD) obesity in low-density lipoprotein receptor knock-out Leiden (Ldlr^−/−.Leiden) mice, and studied the morphological structure of the testes and histologically examined the proportion of Sertoli cells, spermatocytes and spermatids in the seminiferous tubules. We examined sperm DNA damage and chromatin condensation and measured plasma levels of leptin, testosterone, cholesterol and triglycerides. HFD-induced obesity caused high plasma leptin and abnormal testosterone levels and induced an aberrant intra-tubular organisation (ITO) which is associated with an altered spermatids/spermatocytes ratio (2:1 instead of 3:1). Mice fed a HFD had a higher level of tubules in stages VII + VIII in the spermatogenic cycle. The stages VII + VII indicate crucial processes in spermatogenic development like initiation of meiosis, initiation of spermatid elongation, and release of fully matured spermatids. In conclusion, HFD-induced obese Ldlr^−/−.Leiden mice develop an aberrant ITO and alterations in the spermatogenic cycle in crucial stages (stages VII and VII). Thereby, our findings stress the importance of lifestyle guidelines in infertility treatments.

Retrospective Monocentric Clinical Study on Male Infertility: Comparison between Two Different Therapeutic Schemes Using Follicle-Stimulating Hormone

Follicle-stimulating hormone (FSH) is a therapeutic option in patients with idiopathic oligozoospermia and normal FSH serum levels. However, few studies have evaluated which dose of FSH is more effective. The aim of this study was to compare the clinical efficacy of the two most frequently used FSH treatment regimens: 75 IU daily vs. 150 IU three times a week. Patients were retrospectively assigned to two groups. The first group (n = 24) was prescribed highly purified FSH (hpFSH) 75 IU/daily (Group A), and the second group (n = 24) was prescribed hpFSH 150 IU three times a week (Group B) for three months. Before and after treatment, each patient underwent semen analysis, evaluation of the percentage of DNA-fragmented spermatozoa, assessment of testicular volume (by ultrasonography), and measurement of FSH and total testosterone (TT) serum levels. Treatment with hpFSH significantly improved conventional sperm parameters. In detail, sperm concentration increased significantly after treatment only in Group A, whereas total sperm count, percentage of spermatozoa with progressive motility, normal morphology, or alive improved significantly in both groups. Interestingly, the percentage of sperm DNA fragmentation decreased significantly in both groups after treatment with hpFSH. FSH serum levels were expectably higher at the end of the treatment than before hpFSH was administered to both groups. Remarkably, TT serum levels only increased significantly in Group A. Finally, testicular volume was significantly higher in Group A after treatment, while it did not change significantly compared to baseline in Group B. The percentage of FSH responders did not differ significantly between the two groups (8/24 vs. 6/24). The daily administration of hpFSH 75 IU seems more effective than using 150 IU three times a week. However, this therapeutic scheme implies a higher number of injections and slightly higher costs.

Three hour abstinence as a treatment for high sperm DNA fragmentation: a prospective cohort study

PURPOSE

This study sought to compare sperm DNA fragmentation (SDF) in semen specimens after 3 days and then after 3 h of abstinence in men presenting for initial infertility evaluation.

METHODS

A prospective cohort study of 112 men undergoing their first semen analysis as part of an infertility work-up was conducted. All participants presented with 3 days of abstinence for a semen analysis and DNA-fragmentation test. Both tests were repeated on a second sample collected 3 h after the first ejaculation. DNA-fragmentation was evaluated with the halo test by one of two technicians blinded to duration of abstinence. Variables analyzed include ejaculate volume, sperm concentration and motility, smoking status, cannabis use, initial specimen DNA fragmentation, and use of sperm-directed anti-oxidant formulations.

RESULTS

Among all subjects, DNA fragmentation improved in the 3-h abstinence specimen (34.6 ± 19.4% vs. 23.7 ± 16.0%, p = 0.0001). Among subjects with high DNA fragmentation (> 35%) on the initial specimen, 55% improved into the normal range. Semen volume and sperm concentration decreased (3.1 ± 3.3 ml vs. 1.9 ± 0.8 ml, p < 0.01 and 41 ± 39 vs. 32 ± 31 (millions/ml), p = 0.01), while progressive motility tended to increase. Fifty-eight subjects demonstrated ≥ 30% improvement in SDF in the second specimen as compared to the first. Factors found to correlate with > 30% improvement in DNA fragmentation in the 3-h abstinence specimen compared to 3 days were younger age and use of anti-oxidants.

CONCLUSION

High SDF can often be managed with a second ejaculation 3 h after the first in infertile couples, including in males with abnormal semen analyses per the 2010 WHO guide. Apart from SDF levels, changes in sperm quality were not clinically significant in the second specimen and did not increase rates of ICSI. However, a second ejaculation after 3 h probably may reduce the necessity of costly and/or invasive ART strategies.

Relationship between sperm telomere length and sperm quality in infertile men

Telomeres, noncoding and repetitive DNA sequences play a significant function in chromatin integrity. Telomere length is age-dependent in somatic cells, while it increases in sperm cell with age. Therefore, we aimed to assess sperm chromatin, leucocyte and sperm telomere length (LTL, STL) in spermatozoon of 38 infertile and 19 fertile men aged between 20 and 50 years. Protamine deficiency (chromomycin A3 test), DNA fragmentation (TUNEL assay), lipid peroxidation (Bodipy probe) and telomere length (quantitative real-time PCR) were assessed. A significant decrease in mean of sperm concentration and motility and a significant increase in means of sperm abnormal morphology, DNA fragmentation, lipid peroxidation and protamine deficiency were observed in infertile compared with fertile men. In addition, the mean of LTL and STL were significantly shorter in infertile men compared with fertile individuals. We observed significant associations between telomere length with sperm concentration, DNA fragmentation and lipid peroxidation. We hypothesised that increased oxidative stress in spermatozoa of infertile men can result in abnormal packaging of chromatin, damage of DNA and shorter sperm telomere length. Together, these anomalies may account for fertility failure in these individuals.

Measuring Sperm DNA Fragmentation and Clinical Outcomes of Medically Assisted Reproduction: A Systematic Review and Meta-Analysis

Sperm DNA fragmentation has been associated with reduced fertilization rates, embryo quality, pregnancy rates and increased miscarriage rates. Various methods exist to test sperm DNA fragmentation such as the sperm chromatin structure assay (SCSA), the sperm chromatin dispersion (SCD) test, the terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labelling (TUNEL) assay and the single cell gel electrophoresis (Comet) assay. We performed a systematic review and meta-analysis to assess the value of measuring sperm DNA fragmentation in predicting chance of ongoing pregnancy with IVF or ICSI. Out of 658 unique studies, 30 had extractable data and were thus included in the meta-analysis. Overall, the sperm DNA fragmentation tests had a reasonable to good sensitivity. A wide variety of other factors may also affect the IVF/ICSI outcome, reflected by limited to very low specificity. The constructed hierarchical summary receiver operating characteristic (HSROC) curve indicated a fair discriminatory capacity of the TUNEL assay (area under the curve (AUC) of 0.71; 95% CI 0.66 to 0.74) and Comet assay (AUC of 0.73; 95% CI 0.19 to 0.97). The SCSA and the SCD test had poor predictive capacity. Importantly, for the TUNEL assay, SCD test and Comet assay, meta-regression showed no differences in predictive value between IVF and ICSI. For the SCSA meta-regression indicated the predictive values for IVF and ICSI were different. The present review suggests that current sperm DNA fragmentation tests have limited capacity to predict the chance of pregnancy in the context of MAR. Furthermore, sperm DNA fragmentation tests have little or no difference in predictive value between IVF and ICSI. At this moment, there is insufficient evidence to recommend the routine use of sperm DNA fragmentation tests in couples undergoing MAR both for the prediction of pregnancy and for the choice of treatment. Given the significant limitations of the evidence and the methodological weakness and design of the included studies, we do urge for further research on the predictive value of sperm DNA fragmentation for the chance of pregnancy after MAR, also in comparison with other predictors of pregnancy after MAR.

CASA derived human sperm abnormalities: correlation with chromatin packing and DNA fragmentation

PURPOSE

The present study was undertaken to evaluate the effects of morphokinetic abnormalities of human spermatozoa on chromatin packing and DNA integrity and possible beneficial effects of sperm selection in ICSI.

METHODS

Semen samples from 1002 patients were analysed for morphology and motility using CASA. Protamine status and DNA fragmentation were analysed by chromomycin A3 staining and sperm chromatin dispersion assay respectively.

RESULTS

Sperms with elongated, thin, round, pyri, amorphous, micro and macro forms were significantly higher in teratozoospermic and oligoasthenoteratozoospermic groups. Significant difference in chromatin packing and DNA fragmentation index was observed in these abnormal groups compared with normal. Similarly significant correlation was also seen between abnormal motility parameters and DNA fragmentation index in asthenozoospermic group compared with normal.

CONCLUSIONS

Specific abnormal morphological forms have higher incidence of chromatin packing abnormalities and DNA fragmentation. Using these sperms in ICSI might have an impact on fertilization, embryo development and abortion rates. These can be selectively avoided during ICSI procedure to improve ART outcome.

Characterization of sperm chromatin quality in testicular cancer and Hodgkin's lymphoma patients prior to chemotherapy

BACKGROUND

Although the incidences of testicular cancer and Hodgkin's lymphoma have increased in young men over the past decade, combination chemotherapy has improved survival. As fertility is of importance to these patients, characterization of sperm chromatin structure is needed. We assessed sperm chromatin in testicular cancer and Hodgkin's lymphoma patients prior to chemotherapy, in comparison with control community and idiopathic infertile volunteers.

METHODS

DNA damage was assessed with the sperm chromatin structure assay (SCSA), terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and comet assays; reactive thiols (SH) and DNA compaction were determined with the monobromobimane (mBBr) and chromomycin A3 (CMA3) assays, respectively.

RESULTS

Both testicular cancer (37%) and Hodgkin's lymphoma (81%) patients had normospermic samples with increased DNA damage, compared with controls. Cancer patients also had higher reactive thiols and CMA3 staining, indicating low DNA compaction.

CONCLUSIONS

Sperm DNA integrity and compaction were affected in testicular cancer and Hodgkin's lymphoma patients prior to chemotherapy. Although SCSA, TUNEL and comet assays all detected DNA damage, the latter was optimal for use in cancer patients. A combination of the comet assay with tests that evaluate sperm DNA compaction, such as flow cytometry-based CMA3 and mBBr assays, is a reliable strategy to characterize sperm chromatin quality in cancer patients at the time of sperm banking.

Sperm integrity pre- and post-chemotherapy in men with testicular germ cell cancer

BACKGROUND

While (partial) recovery of spermatogenesis, observed by means of standard semen analysis, has been seen in testicular cancer patients after chemotherapy with cisplatin, sperm genomic integrity and its implication for the patient's fertility are poorly understood.

METHODS

Semen and serum from 22 patients treated for testicular cancer were analysed pre- and post-chemotherapy. Besides routine semen analysis, sperm samples were evaluated by computerized karyometric image analysis (CKIA), chromomycin-A3 assay (CMA3, chromatin condensation) and TdT-mediated dUTP nick-end labelling assay (TUNEL, DNA damage). Serum FSH, LH and testosterone concentrations were measured.

RESULTS

Ejaculate volume decreased post-chemotherapy (P<0.05). External sperm characteristics (CKIA morphometry) and sperm counts did not deteriorate after chemotherapy. An improvement in DNA condensation was assessed after chemotherapy (37 versus 50% and 47.5 versus 63.7% for CMA3 and CKIA respectively; both P<0.005); yet a high percentage of TUNEL-positive sperm was found in the samples (21 versus 25% for pre- and post-chemotherapy samples respectively). These values were significantly higher than those of a convenience sample of normozoospermic males attending pre-IVF screening. Serum FSH and LH (IU/l) increased after chemotherapy compared with pretreatment levels (8.1 versus 16.7 and 4.5 vs 6.8; both P<0.05, respectively).

CONCLUSIONS

Despite the improvement in sperm chromatin packaging after chemotherapy, an abnormally high percentage of DNA-damaged sperm was found in these samples. As sperm quality does not reach normal levels after treatment, it remains difficult to outline the best strategy and guidance concerning fertility potential of testicular cancer patients.

Fertilization of in vitro matured human oocytes by intracytoplasmic sperm injection (ICSI) using ejaculated and testicular spermatozoa

AIM

To evaluate the fertilization competence of spermatozoa from ejaculates and testicle when the oocytes were matured in vitro following intracytoplasmic sperm injection (ICSI).

METHODS

Fifty-six completed cycles in 46 women with polycystic ovarian syndrome were grouped according to the semen parameters of their male partners. Group 1 was 47 cycles that presented motile and normal morphology spermatozoa in ejaculates and Group 2 was the other nine cycles where male partners were diagnosed as obstructive azoospermia and spermatozoa could only be found in testicular tissue fragment. All female patients received minimal stimulation with gonadotropin. Immature oocytes were matured in vitro and inseminated by ICSI. The spermatozoa from testes were retrieved by testicular fine needle aspiration.

RESULTS

A total of 449 and 78 immature oocytes were collected and cultured for 48 hours, 75.5 % (339/449) and 84.6 % (66/78) oocytes were matured in Groups 1 and 2, respectively. The percentage of oocytes achieving normal fertilization was significantly higher in Group 1 than that in Group 2 (72.9 % vs. 54.5 %, P 0.05). There were no significant differences in the rates of oocytes cleavage and clinical pregnancies in these two groups [87.4 % (216/247) vs. 88.9 % (32/36); 21.3 % (10/47) vs. 44.4 % (4/9)]. A total of 15 babies in the two groups were healthy delivered at term.

CONCLUSION

It appears that IVM combined with ICSI using testicular spermatozoa can produce healthy infants, while the normal fertilization rate of in vitro matured oocytes after ICSI using testicular spermatozoa was significantly lower than using the ejaculated spermatozoa.

Effect of sperm DNA damage and sperm protamine deficiency on fertilization and embryo development post-ICSI

The aim of this study was to evaluate the effect of sperm DNA damage and protamine deficiency on fertilization and embryo development post-intracytoplasmic sperm injection (ICSI), and also to assess the effect of protamine deficiency on DNA damage. Semen samples were collected from 28 patients participating in the ICSI programme. Following sperm preparation and ICSI, the remaining processed semen samples were used to assess protamine deficiency and DNA damage employing chromomycin A3 (CMA3) staining and comet assay, respectively. Comet parameters, CMA3 percentage positivity, fertilization rate, embryo cleavage score and embryo quality score were assessed. Except for CMA3, none of the comet parameters showed significant correlation with fertilization rate. However, among comet parameters, head area and head intensity showed positive correlation with the embryo cleavage score, while comet mean intensity and head mean intensity showed a significant negative correlation with CMA3 positivity. Results of this study demonstrate that DNA fragmentation is more frequent in protamine-deficient spermatozoa. Unlike protamine deficiency, sperm DNA fragmentation does not preclude fertilization. Nonetheless, embryos derived from spermatozoa with high DNA damage have a lower potential to reach blastocyst stage.