A comparison of DNA damage in testicular and proximal epididymal spermatozoa in obstructive azoospermia

Unraveling the Impact of Sperm DNA Fragmentation on Reproductive Outcomes

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

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.

Modern surgical treatment of azoospermia

PURPOSE OF REVIEW

To review noteworthy research from the last 2 years on surgical management of azoospermia.

RECENT FINDINGS

The recommended treatments for nonobstructive and obstructive azoospermia have not appreciably changed. However, recent level-1 evidence has reinforced superiority of micro-dissection testicular sperm extraction over sperm aspiration in men with nonobstructive azoospermia, and several studies have identified genetic and other clinical factors that may aid in selecting candidates for testicular sperm extraction. Machine learning technology has shown promise as a decision support system for patient selection prior to sperm retrieval as well a tool to aid in sperm identification from testis tissue.

SUMMARY

Most men with obstructive azoospermia who desire fertility can be offered either surgical reconstruction or sperm retrieval. For men with nonobstructive azoospermia, sperm retrieval with microdissection testicular sperm extraction remains the gold standard treatment. Uncovering more genetic causes of nonobstructive azoospermia may aid in properly counseling and selecting patients for microdissection testicular sperm extraction. Neural networks and deep learning may have a future role in patient selection for surgical sperm retrieval and postprocedural sperm identification.

Sperm DNA fragmentation testing: Summary evidence and clinical practice recommendations

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

Peijingsu effectively improves sperm DNA integrity

Intact human sperm DNA is an essential prerequisite for successful fertilization and embryo development. Abnormal sperm DNA fragmentation is a independent factor for male infertility. The objective of this study was to investigate the effects of Peijingsu, a health product, on the DNA integrity of human sperm. Peijingsu was administered for 15 days to 22 patients who had an abnormal sperm DNA fragmentation index (DFI). The DFIs before and after treatment were compared and analyzed using paired t-test. DFIs decreased significantly (P = 0.0008) after treatment, therefore it was concluded that Peijingsu effectively improved sperm DNA integrity in infertile patients who had an abnormal sperm DFI.

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

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

DNA fragmentation of human spermatozoa: Simple assessment of single- and double-strand DNA breaks and their respective dynamic behavioral response

BACKGROUND

Procedures to detect sperm DNA fragmentation (SDF), like the sperm chromatin dispersion (SCD) test, determine the "global" SDF without discriminating between spermatozoa with single-strand DNA breaks only (SDF-SSBs) and those containing double-strand DNA breaks (SDF-DSBs).

OBJECTIVES

(a) To validate a test to distinguish human spermatozoa with massive DSBs (DSB-SCD assay), (b) to study the baseline SDF-SSBs and SDF-DSBs, and (c) to assess their dynamics in vitro.

MATERIALS AND METHODS

(a) SDF-DSBs were determined by visualization of diffused DNA fragments from spermatozoa lysed under non-denaturing conditions. This was validated by in vitro incubation with DNase I and the comet assay. (b) Baseline SDF-DSBs and SDF-SSBs were determined in ejaculates from 95 males. (c) Their dynamic appearance was studied in samples untreated or exposed to hyperthermia, acidic pH, nitric oxide released by sodium nitroprusside (SNP), and the metabolic energy inhibitors 2-deoxy-D-glucose and antimycin A.

RESULTS

(a) DNase I and comet assay experiments confirmed that the assay successfully determined SDF-DSBs. (b) The higher the SDF of the semen sample, the higher the frequency of SSBs, whereas DSBs behaved independently. Abnormal samples showed higher SDF than normozoospermic, the difference being only significant for SDF-SSBs. (c) During the first hours of incubation, the linear rate of increase in SDF-SSBs was 3.7 X higher than that of SDF-DSBs. All hazardous agents accelerated the SDF rate when compared to untreated spermatozoa, primarily being associated with SDF-SSBs. SNP treatment was the most damaging, rapidly inducing spermatozoa with SSBs which progressively evolved to DSBs. Remarkably, this phenomenon was also evidenced after acute SNP exposure, revealing cryptic sperm damage.

CONCLUSION

The DSBs-SCD is an easy complement for SDF assessment. The dynamic study of SSBs and DSBs may improve the evaluation of sperm quality in clinical settings, particularly "unmasking" the presence of non-specific cryptic sperm damage that might otherwise go undetected.

Extended indications for sperm retrieval: summary of current literature

Sperm retrieval combined with intracytoplasmic sperm injection (ICSI) is the treatment of choice for couples with untreatable azoospermia-related infertility. However, an increasing body of evidence has been mounting, suggesting that ICSI with testicular sperm instead of ejaculated sperm (when both are available) increases pregnancy outcomes in some specific scenarios. This has led to the exploration of extended indications for sperm retrieval. This review summarizes the current literature concerning sperm retrieval and ICSI for non-azoospermic men with elevated sperm DNA fragmentation, oligozoospermia, and cryptozoospermia.

Interventions to Prevent Sperm DNA Damage Effects on Reproduction

Excessive oxidation and antioxidant imbalance resulting from several conditions may cause sperm DNA damage, which, in turn, affect male fertility, both natural and assisted. Sperm DNA damage transferred to the embryo might also affect the health of offspring. Several conditions associated with excessive oxidative stress are modifiable by the use of specific treatments, lifestyle changes, and averting exposure to environmental/occupational toxicants. Here, we discuss the strategies to reduce sperm DNA damage with a focus on clinical and surgical interventions.

Use of testicular sperm for intracytoplasmic sperm injection in men with high sperm DNA fragmentation: a SWOT analysis

Spermatozoa retrieved from the testis of men with high levels of sperm DNA fragmentation (SDF) in the neat semen tend to have better DNA quality. Given the negative impact of SDF on the outcomes of Assisted Reproductive Technology (ART), an increased interest has emerged about the use of testicular sperm for intracytoplasmic sperm injection (Testi-ICSI). In this article, we used a SWOT (strengths, weaknesses, opportunities, and threats) analysis to summarize the advantages and drawbacks of this intervention. The rationale of Testi-ICSI is bypass posttesticular DNA fragmentation caused by oxidative stress during sperm transit through the epididymis. Hence, oocyte fertilization by genomically intact testicular spermatozoa may be optimized, thus increasing the chances of creating a normal embryonic genome and the likelihood of achieving a live birth, as recently demonstrated in men with high SDF. However, there is still limited evidence as regards the clinical efficacy of Testi-ICSI, thus creating opportunities for further confirmatory clinical research as well as investigation of Testi-ICSI in clinical scenarios other than high SDF. Furthermore, Testi-ICSI can be compared to other laboratory preparation methods for deselecting sperm with damaged DNA. At present, the available literature supports the use of testicular sperm when performing ICSI in infertile couples whose male partners have posttesticular SDF. Due to inherent risks of sperm retrieval, Testi-ICSI should be offered when less invasive treatments for alleviating DNA damage have failed. A call for continuous monitoring is nonetheless required concerning the health of generated offspring and the potential complications of sperm retrieval.

Low transcriptional activity of PON2 in recurrent abortion: A novel therapeutic agent?

OBJECTIVE

Oxidative stress has been reported to be associated with various pregnancy complications and to play key roles in many of them. An inadequate level of antioxidant defense may eventually lead to an early pregnancy loss. There is a lack of information about the roles of the PON2 and PON3 enzymes in the etiology of the cases of unexplained recurrent abortus. The aim of our study is to determine and present the data regarding the roles of these enzymes for the first time.

MATERIALS AND METHODS

We measured the transcriptional levels of the PON2 and PON3 enzymes in the curettage materials obtained from the patients with unexplained recurrent abortus (n=25) and compared the results with those measured in the abortus materials from healthy pregnant women (n=50) who had undergone a voluntary abortion. The transcriptional activities of PON2 and PON3 enzymes were measured through quantification of their respective mRNAs by RT-qPCR assay. For each gene, 2^-ΔCt replication values of the control and the patient groups were compared using the Student's t-test, and the p values were calculated thereafter. Fold-changes in the enzyme transcription levels were interpreted as up- or down-regulation.

RESULTS

PON2 mRNA expressions were found to be highly decreased in the patient group (p=0.000002). PON3 transcription, when compared to the healthy pregnant women, was found to be down-regulated in the patient group; however, the difference was not statistically significant (p=0.69).

CONCLUSIONS

In this study, we evaluated the expressional regulation of the PON2 and PON3 enzymes in unexplained recurrent abortus. Our results demonstrate for the first time that the expressions of PON2 and PON3 are down-regulated in the abortion specimens of the patients with recurrent miscarriage. Although both enzymes had low expression levels, the decrease in the transcriptional activity of PON2 revealed a high statistical significance. According to these results, it is rational to speculate that PON2 may be a novel therapeutic agent in the management of the cases with unexplained recurrent abortion.

A systematic review on sperm DNA fragmentation in male factor infertility: Laboratory assessment

Objective

To review sperm DNA fragmentation (SDF) testing as an important sperm function test in addition to conventional semen analysis. High SDF is negatively associated with semen quality, the fertilisation process, embryo quality, and pregnancy outcome. Over recent decades, different SDF assays have been developed and reviewed extensively to assess their applicability and accuracy as advanced sperm function tests. Amongst them, the standardisation of the terminal deoxynucleotidyl transferased UTP nick-end labelling (TUNEL) assay with a bench top flow cytometer in clinical practice deserves special mention with a threshold value of 16.8% to differentiate infertile men with DNA damage from fertile men.

Materials and methods

A systematic literature search was performed through the PubMed, Medline, and ScienceDirect databases using the keywords ‘sperm DNA fragmentation’ and ‘laboratory assessment’. Non-English articles were excluded and studies related to humans were only included.

Results

Of the 618 identified, 87 studies (original research and reviews) and in addition eight book chapters meeting the selection criteria were included in this review. In all, 366 articles were rejected in the preliminary screening and a further 165 articles related to non-human subjects were excluded.

Conclusion

There are pros and cons to all the available SDF assays. TUNEL is a reliable technique with greater accuracy and as an additional diagnostic test in Andrology laboratories along with basic semen analysis can predict fertility outcome, and thus direct the choice of an assisted reproductive technology procedure for infertile couples. Also, the TUNEL assay can be used as a prognostic test and results are beneficial in deciding personalised treatment for infertile men.

Reproductive outcomes of testicular versus ejaculated sperm for intracytoplasmic sperm injection among men with high levels of DNA fragmentation in semen: systematic review and meta-analysis

OBJECTIVE

To compare sperm DNA fragmentation (SDF) levels between testicular and ejaculated sperm and to evaluate outcomes of intracytoplasmic sperm injection (ICSI) with the use of testicular (Testi-ICSI) versus ejaculated (Ejac-ICSI) sperm in nonazoospermic men with high SDF.

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENT(S)

Normo- and oligozoospermic men with high levels of SDF in semen subjected to Testi-ICSI or Ejac-ICSI.

INTERVENTION(S)

Summary mean difference (MD) and odds ratio (OR) were calculated with the use of an inverse variance model and fixed- or random-effects models, respectively.

MAIN OUTCOME MEASURE(S)

Primary outcomes were SDF levels, clinical pregnancy rates (CPRs), and live birth rates (LBRs). Secondary outcomes were fertilization and miscarriage rates.

RESULT(S)

Five studies involving 143 patients provided paired SDF rates for testicular and ejaculated sperm, revealing lower SDF in testicular sperm (MD -24.58%). Four studies involving 507 cycles and 3,840 oocytes reported clinical outcomes of Testi-ICSI and Ejac-ICSI. Fertilization rates were not different between sperm sources, but a trend to lower rates was observed with Testi-ICSI. CPRs were higher for Testi-ICSI than for Ejac-ICSI, as were LBRs, whereas miscarriage rates were reduced with Testi-ICSI.

CONCLUSION(S)

Testicular sperm have lower levels of SDF than ejaculated sperm, with Testi-ICSI for high post-testicular SDF men improving reproductive outcomes compared with Ejac-ICSI. Infertile couples may benefit from Testi-ICSI if male partners have confirmed high SDF in the ejaculate.

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.

Comparison of DNA Fragmentation Assay in Frozen-Thawed Cat Epididymal Sperm

DNA fragmentation of frozen-thawed feline epididymal sperm from corpus and cauda regions was evaluated by three different techniques. The DNA fragmentation index (DFI) was compared between techniques: the sperm chromatin structural assay (SCSA(®) ), acridine orange staining techniques (AOT) and the sperm chromatin dispersion (SCD). There were significant differences in DFI among the techniques (p < 0.05) with no correlations. Only DFI values obtained from SCD revealed a significantly higher DFI in corpus compared with cauda spermatozoa (p < 0.05). The discrepancy between techniques might be due to the sensitivity of each technique, differences in severity of DNA damaged that can be detected. The difference in DFI between epididymal regions from SCD technique might indicate different maturational stages of spermatozoa, with less chromatin condensation of spermatozoa in corpus compared with cauda epididymis.

The paternal genome and the health of the assisted reproductive technology child

As a number of children born by assisted reproductive technology (ART) are increasing each year across the developed world, the health of such offspring is a matter of public concern. Does the integrity of the paternal genome impact on offspring health? In societal terms, as birth rates fall, and the Western population become unsustainable, do the benefits outweigh the costs of creating and providing for this ART conceived subpopulation? There are little data to date to answer these questions. The long-term health of such children has largely been ignored, and success measured only by early (prebirth) outcomes such as embryo quality or pregnancy. However, there are powerful paradigms such as ageing and smoking that give vital clues as to the potential impact of unhealthy spermatozoa on disease risk, mental and physical health, fertility and mortality of these offspring.

Comparison of reproductive outcome in oligozoospermic men with high sperm DNA fragmentation undergoing intracytoplasmic sperm injection with ejaculated and testicular sperm

OBJECTIVE

To investigate the effectiveness of intracytoplasmic sperm injection (ICSI) using testicular sperm as a strategy to overcome infertility in men with high sperm DNA fragmentation (SDF).

DESIGN

Prospective, observational, cohort study.

SETTING

Private IVF centers.

PATIENT(S)

A total of 147 couples undergoing IVF-ICSI and day 3 fresh ETs whose male partner has oligozoospermia and high SDF.

INTERVENTION(S)

Sperm injections were carried out with ejaculated sperm (EJA-ICSI) or testicular sperm (TESTI-ICSI) retrieved by either testicular sperm extraction (TESE) or testicular sperm aspiration (TESA). SDF levels were reassessed on the day of oocyte retrieval in both ejaculated and testicular specimens.

MAIN OUTCOME MEASURE(S)

Percentage of testicular and ejaculated spermatozoa containing fragmented DNA (%DFI) and clinical pregnancy, miscarriage, and live-birth rates.

RESULT(S)

The %DFI in testicular sperm was 8.3%, compared with 40.7% in ejaculated sperm. For the TESTI-ICSI group versus the EJA-ICSI group, respectively, the clinical pregnancy rate was 51.9% and 40.2%, the miscarriage rate was 10.0% and 34.3%, and the live-birth rate was 46.7% and 26.4%.

CONCLUSION(S)

ICSI outcomes were significantly better in the group of men who had testicular sperm used for ICSI compared with those with ejaculated sperm. SDF was significantly lower in testicular specimens compared with ejaculated counterparts. Our results suggest that TESTI-ICSI is an effective option to overcome infertility when applied to selected men with oligozoospermia and high ejaculated SDF levels.

Chromosome abnormalities in embryos derived from microsurgical epididymal sperm aspiration and testicular sperm extraction

OBJECTIVE

To evaluate the patterns of chromosome abnormalities in embryos derived from intracytoplasmic sperm injection (ICSI) in microsurgical epididymal sperm aspiration (MESA) or testicular sperm extraction (TESE) in comparison to embryos that are derived from naturally ejaculated (EJAC) patients.

MATERIALS AND METHODS

Male partners with azoospermia who required MESA or TESE for ICSI were studied for chromosomal abnormalities. The ICSI patients with EJAC sperm served as the control group. Preimplantation genetic diagnosis (PGD) was performed by fluorescence in situ hybridization (FISH). Chromosome abnormalities were categorized as polyploidy, haploidy, aneuploidy, and complex abnormality (which involves more than two chromosomes). Fertilization, embryo development, and patterns of chromosome abnormalities were accessed and evaluated.

RESULTS

There was no difference between the MESA, TESE, and EJAC patient groups in the rates of fertilization and pregnancy and the percentages of euploid embryos. In all three groups, less than one-half of the embryos for each group were normal (41 ± 31%, 48 ± 38%, and 48 ± 31% in MESA, TESA, and EJAC, respectively). Complex chromosomal abnormality was significantly more frequent in the MESA group than in the EJAC group (48.3% vs. 26.5%, respectively; p < 0.001). Furthermore, the overall pattern of chromosomal aneuploidy was similar among all three studied groups.

CONCLUSION

We suggest that MESA and TESE, followed by ICSI and PGD, appear to be acceptable approaches for treating men with severe spermatogenesis impairment.

Unexplained male infertility: diagnosis and management

Unexplained male infertility is a diagnosis reserved for men in whom routine semen analyses results are within normal values and physical as well as endocrine abnormalities were ruled out. In addition to erectile problems and coital factors, immunologic causes and sperm dysfunction may contribute to such condition. New etiologies of unexplained male infertility include low level leukocytospermia and mitochondrial DNA polymerase gene polymorphism. Contemporary andrology may reveal cellular and sub-cellular sperm dysfunctions which may explain subfertility in such cases, thus aiding the clinician to direct the further work-up, diagnosis and counseling of the infertile male. The objective of this article is to highlight the concept of unexplained male infertility and focuses on the diagnosis and treatment of this condition in the era of modern andrology and assisted reproductive techniques. Extensive literature review was performed using the search engines: Pubmed, Science-direct, Ovid and Scopus.

Cannabinoid receptor 1 influences chromatin remodeling in mouse spermatids by affecting content of transition protein 2 mRNA and histone displacement

Marijuana smokers and animals treated with Δ9-tetrahydrocannabinol, the principal component of marijuana, show alterations of sperm morphology suggesting a role for cannabinoids in sperm differentiation and/or maturation. Because the cannabinoid receptor 1 (CNR1) activation appears to play a pivotal role in spermiogenesis, the developmental stage where DNA is remodeled, we hypothesized that CNR1 receptors might also influence chromatin quality in sperm. We used Cnr1 null mutant (Cnr1-/-) mice to study the possible role of endocannabinoids on sperm chromatin during spermiogenesis. We demonstrated that CNR1 activation regulated chromatin remodeling of spermatids by either increasing Tnp2 levels or enhancing histone displacement. Comparative analysis of wild-type, Cnr1+/-, and Cnr1-/- animals suggested the possible occurrence of haploinsufficiency for Tnp2 turnover control by CNR1, whereas histone displacement was disrupted to a lesser extent. Furthermore, flow cytometry analysis demonstrated that the genetic loss of Cnr1 decreased sperm chromatin quality and was associated with sperm DNA fragmentation. This damage increased during epididymal transit, from caput to cauda. Collectively, our results show that the expression/activity of CNR1 controls the physiological alterations of DNA packaging during spermiogenesis and epididymal transit. Given the deleterious effects of sperm DNA damage on male fertility, we suggest that the reproductive function of marijuana users may also be impaired by deregulation of the endogenous endocannabinoid system.

Does the outcome of ICSI in cases of obstructive azoospermia depend on the origin of the retrieved spermatozoa or the cause of obstruction? A comparative analysis

OBJECTIVE

To compare the outcomes of intracytoplasmic sperm injection (ICSI) for men with obstructive azoospermia and normal spermatogenesis, according to the use of epididymal or testicular spermatozoa and the cause of obstruction.

DESIGN

Retrospective study.

SETTING

Private infertility center.

PATIENT(S)

A detailed chart review of a cohort of 1,121 men with obstructive azoospermia who underwent intracytoplamic sperm injection (ICSI) was performed.

INTERVENTION(S)

Patients were grouped according to the origin of spermatozoa: epididymal (n=331) or testicular (n=790). They were further classified into two subgroups according to the cause of obstruction: congenital bilateral absence of vas deferens (CBAVD; n=434), and other causes of obstruction (n=687).

MAIN OUTCOME MEASURE(S)

Fertilization, clinical pregnancy, and miscarriage rates.

RESULT(S)

Fertilization (64.2% vs. 68.0%), clinical pregnancy (42.3% vs. 43.2%), and miscarriage (17.6% vs. 18.4%) rates did not differ between epididymal spermatozoa and testicular spermatozoa, respectively. Fertilization, clinical pregnancy, and miscarriage rates were also similar in the patients with CBAVD or due to other causes of obstruction.

CONCLUSION(S)

The source of sperm used for ICSI in cases of obstructive azoospermia and the etiology of the obstruction do not affect the outcome in terms of fertilization, pregnancy, or miscarriage rates.

Sperm DNA fragmentation: mechanisms of origin, impact on reproductive outcome, and analysis

OBJECTIVE

To review the mechanisms responsible for DNA fragmentation in human sperm, including those occurring during spermatogenesis and transport through the reproductive tract. The mechanisms examined include: apoptosis in the seminiferous tubule epithelium, defects in chromatin remodeling during the process of spermiogenesis, oxygen radical-induced DNA damage during sperm migration from the seminiferous tubules to the epididymis, the activation of sperm caspases and endonucleases, damage induced by chemotherapy and radiotherapy, and the effect of environmental toxicants. The different tests currently used for sperm DNA fragmentation analysis and the factors that determine the predictive value of sperm DNA fragmentation testing and their implications in the diagnosis and treatment of infertility are also discussed. Finally, we also scrutinize how the presence in the embryonic genome of DNA strand breaks or modifications of DNA nucleotides inherited from the paternal genome could impact the embryo and offspring. In particular we discuss how abnormal sperm could be dealt with by the oocyte and how sperm DNA abnormalities, which have not been satisfactorily repaired by the oocyte after fertilization, may interfere with normal embryo and fetal development.

CONCLUSION(S)

Sperm DNA can be modified through various mechanisms. The integrity of the paternal genome is therefore of paramount importance in the initiation and maintenance of a viable pregnancy both in a natural conception and in assisted reproduction. The need to diagnose sperm at a nuclear level is an area that needs further understanding so that we can improve treatment of the infertile couple.

Pregnancies and live births following ICSI with testicular spermatozoa after repeated implantation failure using ejaculated spermatozoa

The use of testicular spermatozoa for IVF/intracytoplasmic sperm injection (ICSI) is currently indicated exclusively for patients with azoospermia, since a favourable outcome is expected even when very few spermatozoa are present in the ejaculate. Here, a series of four couples with long-standing male factor infertility and multiple failed IVF/ICSI cycles are described. In all couples, the use of ejaculated spermatozoa for ICSI resulted in poor embryo quality and repeated implantation failure. Testicular sperm aspiration was performed in subsequent cycles, and testicular spermatozoa were used for ICSI. Embryo implantation and ongoing pregnancies/deliveries were achieved in all four couples. It is postulated that spermatozoa are subjected to post-testicular damage during sperm transport between the seminiferous tubules and epididymis, with the injection of damaged spermatozoa being the cause for repetitive IVF/ICSI failures. In selected patients, the use of testicular spermatozoa for IVF/ICSI should be considered, even when motile spermatozoa can be identified in the ejaculate.

Testicular spermatozoa have statistically significantly lower DNA damage compared with ejaculated spermatozoa in patients with unsuccessful oral antioxidant treatment

OBJECTIVE

To compare DNA damage in ejaculated and testicular spermatozoa in patients with previously unsuccessful oral antioxidant treatment.

DESIGN

Prospective clinical study.

SETTING

University-affiliated teaching hospital.

PATIENT(S)

Twelve men with persistently high sperm DNA damage.

INTERVENTION(S)

Evaluation of DNA damage of ejaculated and testicular spermatozoa by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) assay.

MAIN OUTCOME MEASURE(S)

The DNA damage of ejaculated spermatozoa compared with that of testicular spermatozoa, both samples collected on the day of intracytoplasmic sperm injection.

RESULT(S)

Ejaculated spermatozoa showed a threefold higher DNA damage when compared with testicular samples (39.7% +/- 14.8 vs. 13.3% +/- 7.3).

CONCLUSION(S)

Our results indicated that in patients with previously unsuccessful oral antioxidant treatment the retrieved testicular spermatozoa had a lower degree of DNA damage compared with ejaculated sperm collected on the same day.

Redox considerations in female reproductive function and assisted reproduction: from molecular mechanisms to health implications

Physiological levels of reactive oxygen species (ROS) play an important regulatory role through various signaling transduction pathways in folliculogenesis, oocyte maturation, endometrial cycle, luteolysis, implantation, embryogenesis, and pregnancy. Persistent and elevated generation of ROS leads to a disturbance of redox potential that in turn causes oxidative stress (OS). Our literature review captures the role of ROS in modulating a range of physiological functions and pathological processes affecting the female reproductive life span and even thereafter (i.e., menopause). The role of OS in female reproduction is becoming increasingly important, as recent evidence suggest that it plays a part in conditions such as polycystic ovarian disease, endometriosis, spontaneous abortions, preeclampsia, hydatidiform mole, embryopathies, preterm labor, and intrauterine growth retardation. OS has been implicated in different reproductive scenarios and is detrimental to both natural and assisted fertility. Many extrinsic and intrinsic conditions exist in assisted reproduction settings that can be tailored to reduce the toxic effects of ROS. Laboratory personnel should avoid procedures that are known to be deleterious, especially when safer procedures that can prevent OS are available. Although antioxidants such as folate, zinc, and thiols may help enhance fertility, the available data are contentious and must be evaluated in controlled studies with larger populations.

The outcome of intracytoplasmic sperm injection using occasional spermatozoa in the ejaculate of men with spermatogenic failure

PURPOSE

Men with spermatogenic failure so profound that they are considered as having nonobstructive azoospermia occasionally have spermatozoa in the ejaculate. We compared intracytoplasmic sperm injection outcomes following the injection of ejaculated or surgically retrieved spermatozoa from these men.

MATERIALS AND METHODS

A study was performed of intracytoplasmic sperm injection cycles with no spermatozoa on initial semen analysis and 100 or fewer following centrifugation (cryptozoospermia). Only 16 couples that underwent intracytoplasmic sperm injection cycles with ejaculated spermatozoa and cycles with testicular spermatozoa were included.

RESULTS

Initial analysis was done to compare outcomes between the 2 semen origins. There was no difference in the rate of normal or abnormal fertilization between the 2 groups. The rate of clinical pregnancies seemed to favor testicular spermatozoa (47.4% vs 20.8%), although results were not significant. When a comparison was performed between the first testicular cycle and the ejaculated cycle closest in time to the cycle with testicular spermatozoa, a higher rate of normal fertilization with testicular spermatozoa was observed (60.9% vs 48.5%, p <0.05). Also, in this comparison a clear trend toward a higher percent of clinical pregnancies and deliveries in the testicular group was observed (50.0% vs 14.3%).

CONCLUSIONS

Transit through the male genital tract did not enhance the ability of ejaculated spermatozoa to achieve fertilization with intracytoplasmic sperm injection compared to that of testicular spermatozoa in men with severely impaired production. In ejaculated samples a lower number of spermatozoa available resulted in an impaired chance of achieving pregnancy. Using testicular spermatozoa may be a reasonable alternative for couples in whom multiple attempts at intracytoplasmic sperm injection have failed using ejaculated sperm from men with cryptozoospermia.

Antioxidant therapy in male infertility

Although reports have suggested the benefit of antioxidant treatment of infertile men, many studies also show no effect. Most studies in the literature are not randomized, placebo controlled, or double blinded in design, which makes it difficult to differentiate regression toward the mean from true positive treatment effects. The small patient sample sizes and varying male populations also add to the difficulty in comparing studies. Pregnancy, the most relevant outcome parameter, is rarely reported. Ideally, patients would be selected based on oxidative stress levels, and improvement in these levels would be correlated to improvement in pregnancy rates. Until those studies are performed, the use of antioxidants for the treatment of male infertility remains empiric.

The comet assay in male reproductive toxicology

Due to our lifestyle and the environment we live in, we are constantly confronted with genotoxic or potentially genotoxic compounds. These toxins can cause DNA damage to our cells, leading to an increase in mutations. Sometimes such mutations could give rise to cancer in somatic cells. However, when germ cells are affected, then the damage could also have an effect on the next and successive generations. A rapid, sensitive and reliable method to detect DNA damage and assess the integrity of the genome within single cells is that of the comet or single-cell gel electrophoresis assay. The present communication gives an overview of the use of the comet assay utilising sperm or testicular cells in reproductive toxicology. This includes consideration of damage assessed by protocol modification, cryopreservation vs the use of fresh sperm, viability and statistics. It further focuses on in vivo and in vitro comet assay studies with sperm and a comparison of this assay with other assays measuring germ cell genotoxicity. As most of the de novo structural aberrations occur in sperm and spermatogenesis is functional from puberty to old age, whereas female germ cells are more complicated to obtain, the examination of male germ cells seems to be an easier and logical choice for research and testing in reproductive toxicology. In addition, the importance of such an assay for the paternal impact of genetic damage in offspring is undisputed. As there is a growing interest in the evaluation of genotoxins in male germ cells, the comet assay allows in vitro and in vivo assessments of various environmental and lifestyle genotoxins to be reliably determined.

Effect of pressure at primary drying of freeze-drying mouse sperm reproduction ability and preservation potential

Freeze-dried spermatozoa are capable of participating in normal embryonic development after injection into oocytes and thus useful for the maintenance of genetic materials. We recently reported that long-term preservation of freeze-dried mouse spermatozoa by conventional methods requires temperatures lower than -80 degrees C. Successful permanent preservation of mouse spermatozoa at much higher temperatures requires thorough investigation of the freeze-drying procedure. Thus, we examined the relationship between the pressure at primary drying and the preservation potential of freeze-dried mouse spermatozoa. Three different primary drying pressures were applied to evaluate the effect of pressure on freeze-dried spermatozoa under varying storage conditions and the rate of development measured. The developmental rate of embryos to the blastocyst stage from intracytoplasmic sperm injection by freeze-dried spermatozoa at pressures of 0.04, 0.37, and 1.03 mbar without storage were 59% (337/576), 71% (132/187), and 33% (99/302) respectively. When stored at 4 degrees C for 6 months, the rate was 13% (48/367), 50% (73/145), and 36% (66/182) respectively. These results show that primary drying pressure is an influential factor in the long-term preservation of freeze-dried mouse spermatozoa.

The role of oxidative stress in spontaneous abortion and recurrent pregnancy loss: a systematic review

Human reproduction is not considered a highly efficient biological process. Before the end of the first trimester, 30%-50% of conceptions end in spontaneous abortion. Most losses occur at the time of implantation. 15%-20% of clinical pregnancies end in spontaneous abortions. Recurrent pregnancy loss is a frustrating clinical problem both for clinicians and patients. Recurrent pregnancy loss affects 0.5%-3% of women in the reproductive age group, and between 50%-60% of recurrent pregnancy losses are idiopathic. Oxidative stress-induced damage has been hypothesized to play a role in spontaneous abortion, idiopathic recurrent pregnancy loss, hydatidiform mole, defective embryogenesis, and drug-induced teratogenicity. Some studies implicate systemic and placental oxidative stress in the pathophysiology of abortion and recurrent pregnancy loss. Oxidant-induced endothelial damage, impaired placental vascularization and immune malfunction have all been proposed to play a role in the pathophysiology of idiopathic recurrent pregnancy loss. Oxidative stress-induced placental dysfunction may be a common cause of the multifactorial and polygenic etiologies of abortion, recurrent pregnancy loss, defective embryogenesis, hydatidiform mole, and drug-induced teratogenic effects. Oxidative stress-induced modification of phospholipids has been linked to the formation of antiphospholipid antibodies in the antiphospholipid syndrome. The objective of this review was to examine the association between oxidative stress, spontaneous abortion and recurrent pregnancy loss, based on the published literature. We conducted an extensive literature search utilizing the databases of Medline, CINAHL, and Cochrane from 1986 to 2005. The following keywords were used: oxidative stress, abortion, recurrent pregnancy loss, reactive oxygen species, antioxidants, fetal development, and embryopathies. We conducted an electronic search, as well as a manual search of cross-references. We have included all studies in the English language found in the literature focusing on oxidative stress and its association with abortions, recurrent pregnancy loss and drug-induced teratogenicity. The role of antioxidant vitamins for primary prevention of oxidative stress-induced pathologies needs to be investigated further.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to state that the causes of spontaneous and recurrent abortion are multifaceted, however, some of the causes may be preventable and also explain that the role of oxidative stress during pregnancy and adverse pregnancy outcomes has a basis in pathophysiology, although the role of oxidative stress and the treatment of oxidative stress during or before pregnancy remains speculative.