Correlation between male age, WHO sperm parameters, DNA fragmentation, chromatin packaging and outcome in assisted reproduction technology

Advanced Paternal Age in Focus: Unraveling Its Influence on Assisted Reproductive Technology Outcomes

As global demographics shift toward increasing paternal age, the realm of assisted reproductive technologies (ARTs), particularly in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), faces new challenges and opportunities. This study provides a comprehensive exploration of the implications of advanced paternal age on ART outcomes. Background research highlights the social, cultural, and economic factors driving men toward later fatherhood, with a focus on the impact of delayed paternity on reproductive outcomes. Methods involve a thorough review of existing literature, centering on changes in testicular function, semen quality, and genetic and epigenetic shifts associated with advancing age. Study results point to intricate associations between the father's age and ART outcomes, with older age being linked to diminished semen quality, potential genetic risks, and varied impacts on embryo quality, implantation rates, and birth outcomes. The conclusions drawn from the current study suggest that while advanced paternal age presents certain risks and challenges, understanding and mitigating these through strategies such as sperm cryopreservation, lifestyle modifications, and preimplantation genetic testing can optimize ART outcomes. Future research directions are identified to further comprehend the epigenetic mechanisms and long-term effects of the older father on offspring health. This study underscores the need for a comprehensive approach in navigating the intricacies of delayed fatherhood within the context of ART, aiming for the best possible outcomes for couples and their children.

The impact of paternal age on cumulative assisted reproductive technology outcomes

Objective

To investigate the impact of paternal age on cumulative live birth rate in ART.

Design

Retrospective single-center cohort study.

Patients

All female patients aged 18-43 years and male patients aged 18-60 years, who performed their first ART cycle between January 2018 and December 2020, were included.

Main outcome measures

The primary outcome, cumulative live birth rate (cLBR), was estimated following fresh or frozen embryo transfers issued from an ART cycle. Secondary outcomes included the cumulative pregnancy rate (cPR) and miscarriage rate. Subgroup analyzes were performed as follows: men <45 and ≥ 45; female <35, 35-38, and > 38 years.

Results

A total of 2,358 couples were included in this study. The sperm quantity of male patients within both age groups was divided in two groups: normal and abnormal, which were found to be in significantly equal proportions. There were significantly fewer current smokers in the male group ≥45. The cPR was 0.5301 in the group <45 and 0.3111 in the group ≥45, with a p-value <0.001. Analysis according to the female age revealed that, in the female group >38, the cLBR rate was 0.26 for men <45 and 0.19 for men ≥45, with a p-value of 0.061. Additionally, the cPR was 0.34 in the male group <45 and 0.21 in the group ≥45, with a p-value <0.001. In the female group between 35 and 38 years of age, the cLBR was 0.44 in the male group <45 and 0.3 in the male group ≥45, with a p-value of 0.031. The cPR was 0.49 in the male group <45 and 0.34 in the group ≥45, p = 0.036. Within the female group <35, we observed non-significant results. The miscarriage rate results were not significantly different for women ≤38.

Conclusion

According to the results from our study, male age ≥ 45 has a significant impact on cumulative ART outcomes.

Sperm chromatin structure assay (SCSA®) and flow cytometry-assisted TUNEL assay provide a concordant assessment of sperm DNA fragmentation as a function of age in a large cohort of approximately 10,000 patients

BACKGROUND

Sperm DNA integrity is increasingly seen as a critical characteristic determining reproductive success, both in natural reproduction and in assisted reproductive technologies (ART). Despite this awareness, sperm DNA and nuclear integrity tests are still not part of routine examinations for either infertile men or fertile men wishing to assess their reproductive capacity. This is not due to the unavailability of DNA and sperm nuclear integrity tests. On the contrary, several relevant but distinct tests are available and have been used in many clinical trials, which has led to conflicting results and confusion. The reasons for this are mainly the lack of standardization between different clinics and between the tests themselves. In addition, the small number of samples analyzed in these trials has often weakened the value of the analyses performed. In the present work, we used a large cohort of semen samples, covering a wide age range, which were simultaneously evaluated for sperm DNA fragmentation (SDF) using two of the most frequently used SDF assays, namely the TUNEL assay and the sperm chromatin structure assay (SCSA®). At the same time, as standard seminal parameters (sperm motility, sperm morphology, sperm count) were available for these samples, correlations between age, SDF and conventional seminal parameters were analyzed.

RESULTS

We show that the SCSA® and TUNEL assessments of SDF produce concordant data. However, the SDF assessed by TUNEL is systematically lower than that assessed by SCSA®. Regardless of the test used, the SDF increases steadily during aging, while the HDS parameter (High DNA stainability assessed via SCSA®) remains unchanged. In the cohort analyzed, conventional sperm parameters do not seem to discriminate with aging. Only sperm volume and motility were significantly lower in the oldest age group analyzed [50-59 years of age].

CONCLUSIONS

In the large cohort analyzed, SDF is an age-dependent parameter, increasing linearly with aging. The SCSA® assessment of SDF and the flow cytometry-assisted TUNEL assessment are well correlated, although TUNEL is less sensitive than SCSA®. This difference in sensitivity should be taken into account in the final assessment of the true level of fragmentation of the sperm nucleus of a given sample. The classical sperm parameters (motility, morphology, sperm count) do not change dramatically with age, making them inadequate to assess the fertility potential of an individual.

Does reciprocal translocation affect the meiotic segregation products of non-translocation chromosomes?

This retrospective cohort study aimed to assess the effect of chromosomal reciprocal translocation on meiotic segregation products of non-translocation chromosomes. A total of 744 reciprocal translocation carriers and 875 non-carriers were included in this study. A total of 6,832 blastocysts were biopsied and tested by next-generation sequencing. Blastocysts from the carrier group were classified into five subgroups according to the theoretical segregation pattern of quadrivalent structure. For carrier patients, normal meiotic segregation products of the non-translocation chromosome were classified after excluding the segregation modes of the quadrivalent structure. The proportion of normal non-translocation chromosome meiotic segregation products was similar between the carrier and noncarrier groups (p = 0.69). The generalized Estimation Equation revealed that there was no correlation between reciprocal translocation and meiotic segregation products of non-translocation chromosomes. Moreover, subgroup analyses showed that the segregation modes of quadrivalent structure (p = 0.00) and carrier's gender (p = 0.00) may affect the meiotic segregation products of non-translocation chromosomes. In conclusion, reciprocal translocation does not directly reduce the proportion of normal segregation products of non-translocation chromosomes. The difference among subgroups of different quadrivalent segregation patterns implied that interchromosomal effect may exist but the high incidence of chromosomal abnormalities for reciprocal translocation carriers should not be attributed to interchromosomal effect.

Advanced Paternal Age Affects the Sperm DNA Fragmentation Index and May Lead to Lower Good-quality Blastocysts

Several studies show reductions in some seminal parameters in aged men and describe them as a consequence of many age-dependent changes in male organisms. This study aims to evaluate the impact of age on seminal parameters, particularly the DNA fragmentation index (DFI), and outcomes after in vitro fertilization (IVF) cycles. This is a retrospective study that includes 367 patients who underwent sperm chromatin structure assay testing between 2016 and 2021. The participants were split into three groups according to age: < 35 years (younger group, n = 63), 35-45 years (intermediate group, n = 227), and ≥ 45 years (older group, n = 77). The mean DFI (%) was compared. Among all patients, 255 received IVF cycles after DFI evaluation. For these patients, the sperm concentration, motility, and volume, as well as the fertilization rate, mean oocyte age, and good-quality blastocyst formation rate, were analyzed. One-way ANOVA was applied. The older group showed a significantly higher sperm than did the younger group (28.6% vs. 20.8% p = 0.0135). Despite not presenting a significant difference, the DFI level tends to be inversely related to good-quality blastocyst formation since the oocyte age was similar between the groups (32.0 v.s 33.6 vs. 32.3 years, respectively, p = 0.1183). Among aged men, the sperm DFI level is increased but other seminal parameters are not modified. Considering that men with a high sperm DFI can present some degree of infertility due to high sperm chromatin damage, male age should also be considered a limiting factor of IVF.

Impact of Advanced Paternal Age on Fertility and Risks of Genetic Disorders in Offspring

The average age of fathers at first pregnancy has risen significantly over the last decade owing to various variables, including a longer life expectancy, more access to contraception, later marriage, and other factors. As has been proven in several studies, women over 35 years of age have an increased risk of infertility, pregnancy problems, spontaneous abortion, congenital malformations, and postnatal issues. There are varying opinions on whether a father's age affects the quality of his sperm or his ability to father a child. First, there is no single accepted definition of old age in a father. Second, much research has reported contradictory findings in the literature, particularly concerning the most frequently examined criteria. Increasing evidence suggests that the father's age contributes to his offspring's higher vulnerability to inheritable diseases. Our comprehensive literature evaluation shows a direct correlation between paternal age and decreased sperm quality and testicular function. Genetic abnormalities, such as DNA mutations and chromosomal aneuploidies, and epigenetic modifications, such as the silencing of essential genes, have all been linked to the father's advancing years. Paternal age has been shown to affect reproductive and fertility outcomes, such as the success rate of in vitro fertilisation (IVF), intracytoplasmic sperm injection (ICSI), and premature birth rate. Several diseases, including autism, schizophrenia, bipolar disorders, and paediatric leukaemia, have been linked to the father's advanced years. Therefore, informing infertile couples of the alarming correlations between older fathers and a rise in their offspring's diseases is crucial, so that they can be effectively guided through their reproductive years.

The role of spermatozoa-zona pellucida interaction in selecting fertilization-competent spermatozoa in humans

Human fertilization begins when a capacitated spermatozoon binds to the zona pellucida (ZP) surrounding a mature oocyte. Defective spermatozoa-ZP interaction contributes to male infertility and is a leading cause of reduced fertilization rates in assisted reproduction treatments (ARTs). Human ejaculate contains millions of spermatozoa with varying degrees of fertilization potential and genetic quality, of which only thousands of motile spermatozoa can bind to the ZP at the fertilization site. This observation suggests that human ZP selectively interacts with competitively superior spermatozoa characterized by high fertilizing capability and genetic integrity. However, direct evidence for ZP-mediated sperm selection process is lacking. This study aims to demonstrate that spermatozoa-ZP interaction represents a crucial step in selecting fertilization-competent spermatozoa in humans. ZP-bound and unbound spermatozoa were respectively collected by a spermatozoa-ZP coincubation assay. The time-course data demonstrated that ZP interacted with a small proportion of motile spermatozoa. Heat shock 70 kDa protein 2 (HSPA2) and sperm acrosome associated 3 (SPACA 3) are two protein markers associated with the sperm ZP-binding ability. Immunofluorescent staining indicated that the ZP-bound spermatozoa had significantly higher expression levels of HSPA2 and SPACA3 than the unbound spermatozoa. ZP-bound spermatozoa had a significantly higher level of normal morphology, DNA integrity, chromatin integrity, protamination and global methylation when compared to the unbound spermatozoa. The results validated the possibility of applying spermatozoa-ZP interaction to select fertilization-competent spermatozoa in ART. This highly selective interaction might also provide diagnostic information regarding the fertilization potential and genetic qualities of spermatozoa independent of those derived from the standard semen analysis.

Paternal age impairs in vitro embryo and in vivo fetal development in murine

The association between advanced paternal age and impaired reproductive outcomes is still controversial. Several studies relate decrease in semen quality, impaired embryo/fetal development and offspring health to increased paternal age. However, some retrospective studies observed no alterations on both seminal status and reproductive outcomes in older men. Such inconsistency may be due to the influence of intrinsic and external factors, such as genetics, race, diet, social class, lifestyle and obvious ethical issues that may bias the assessment of reproductive status in humans. The use of the murine model enables prospective study and owes the establishment of homogeneous and controlled groups. This study aimed to evaluate the effect of paternal age on in vitro embryo development at 4.5 day post conception and on in vivo fetal development at 16 days of gestation. Murine females (2–4 months of age) were mated with young (4–6 months of age) or senile (18–24 months of age) males. We observed decreased in vitro cleavage, blastocyst, and embryo development rates; lighter and shorter fetuses in the senile compared to the young group. This study indicated that advanced paternal age negatively impacts subsequent embryo and fetal development.

Factors Affecting Artificial Insemination Pregnancy Outcome

Objective

The aim of the present study was to explore related clinical pregnancy outcome factors in intrauterine insemination (IUI).

Materials and Methods

The clinical data of 3984 IUI cycles in 1862 couples experiencing infertility who attended the Reproductive Center of Binzhou Medical University Hospital between July 2006 and July 2017 were retrospectively analyzed. Female and male patient age, endometrial thickness (EMT), the post-wash total motile sperm count (PTMC), artificial insemination timing, insemination frequency, and ovarian stimulation protocols were compared between the study’s pregnant group and non-pregnant group in order to explore any correlation.

Results

There were statistically significant differences in female and male age, EMT, artificial insemination timing, insemination frequency, and ovarian stimulation protocols between the two groups (p < 0.05). The clinical pregnancy rate was significantly higher in ovarian stimulation cycles than in natural cycles (21.2% and 11.6%, respectively; p < 0.01), the clinical pregnancy rate was significantly higher in double IUI than in single IUI (17.8% and 12.1%, respectively; p < 0.01), and EMT was significantly greater in the pregnant group than in the control group (p < 0.05). However, the differences in clinical pregnancy rates among the PTMC groups were not statistically significant (14.8%, 14.4%, 17.3%, and 17.3%, respectively; p > 0.05).

Conclusion

The results of the present study demonstrate that the clinical IUI pregnancy rate is correlated with the factors of female age, male age, EMT, artificial insemination timing, insemination frequency, and ovarian stimulation protocols; the ovarian stimulation protocol can noticeably improve the patient pregnancy outcome. Furthermore, compared with single IUI, double IUI can significantly increase the clinical pregnancy rate.

The effect of sperm DNA fragmentation on intracytoplasmic sperm injection outcome

Our study objective was to assess the effect of various sperm DNA fragmentation levels on clinical intracytoplasmic sperm injection outcome. This retrospective study included 392 patients who underwent ICSI and performed sperm DNA fragmentation testing before the procedure. Based on sperm DNA fragmentation cut-off values, the patients were differentiated into 3 groups as <20%, 20%-30% and >30%. According to the female status, patients were differentiated into favourable group (n = 259) with female age <35 years and anti-Mullerian hormone level ≥7.1 pmol/L; and unfavourable group (n = 133) with female age ≥35 years and anti-Mullerian hormone level ≤7.1 pmol/L. The patient's medical records were reviewed, and patient's demographic, laboratory data including semen analysis, sperm DNA fragmentation determined by means of sperm chromatin dispersion, hormonal profile and data regarding intracytoplasmic sperm injection cycle were collected. This cohort reported that the clinical reproductive outcomes of intracytoplasmic sperm injection showed no statistical significance with increase sperm DNA fragmentation levels. In sperm DNA fragmentation above 30%, favourable females had significantly higher clinical pregnancy rate and live birth rate than unfavourable females, while fertilisation rate and miscarriage rate showed no significance between the subgroups. High sperm DNA fragmentation is linked to poor semen parameters.

Advanced Paternal Age and Sperm DNA Fragmentation: A Systematic Review

Purpose

Male ageing is often associated with defective sperm DNA remodeling mechanisms that result in poorly packaged chromatin and a decreased ability to repair DNA strand breaks. However, the impact of advanced paternal age on DNA fragmentation remains inconclusive. The aim of the present systematic review was to investigate the impact of advancing paternal age (APA) on DNA fragmentation.

Materials and Methods

We conducted a thorough search of listed publications in Scopus, PubMed, and EMBASE, in accordance with the PRISMA guidelines.

Results

We identified 3,120 articles, of which nineteen were selected for qualitative analysis, resulting in a sample of 40,668 men. Of the 19 articles evaluating the impact of APA on DFI% (DNA fragmentation Index) included, 4 were on Normozoospermic and subfertile men, 3 on normozoospermic, Oligoasthenoteratozoospermic and Teratozoospermic, 6 on fertile and infertile men, 4 on just infertile men, and 2 evaluated a general population. Seventeen of the ninrnteen studies demonstrated APA's effect and impact on DFI%.

Conclusions

Although there was no universal definition for APA, the present review suggests that older age is associated with increased DFI. In elderly men with normal semen parameters, further studies should be performed to assess the clinical implications of DFI, as a conventional semen analysis can often fail to detect an etiology for infertility.

Age-related changes in human conventional semen parameters and sperm chromatin structure assay-defined sperm DNA/chromatin integrity

RESEARCH QUESTION

What are the correlations between male age, traditional semen parameters, sperm DNA fragmentation index (DFI) and high DNA stainability (HDS) in a sufficiently large sample size?

DESIGN

Retrospective cohort study of 18,441 semen samples, with data divided into seven age groups according to male age: ≤25, 26-30, 31-35, 36-40, 41-45, 46-50 and ≥51 years.

RESULTS

Age was negatively correlated with semen volume, total sperm count, motility and HDS, and positively correlated with sperm concentration and DFI (P < 0.001). After 35 years of age, semen volume and total sperm count began to decline. After 30 years of age, motility and HDS decreased consistently. Sperm concentration and DFI increased from 26-30 years of age. DFI was negatively correlated with sperm concentration, total sperm count, motility and normal morphology (P < 0.001) and positively correlated with semen volume and HDS (P < 0.001). HDS was negatively correlated with all parameters (P < 0.001) except semen volume (r = -0.013, P = 0.074) and DFI (r = 0.124, P < 0.001). Patients aged ≥40 years had higher DFI than those aged <40 years in the entire cohort, in the abnormal semen parameters cohort, and in the normal semen parameters cohort (OR 2.145, 2.042, 1.948, respectively, P < 0.001). The ≥40 years age group had a lower HDS than the <40 years age group in the entire cohort and abnormal semen parameters cohort (OR 0.719, 0.677, respectively, P < 0.001).

CONCLUSIONS

Ageing is a negative effector of sperm quantity and quality, and routine sperm parameters have weak but significant correlations with sperm DNA/chromatin integrity.

Advanced paternal age: effects on sperm parameters, assisted reproduction outcomes and offspring health

Many factors, including postponement of marriage, increased life expectancy, and improved success with assisted reproductive technologies have been contributing to increased paternal age in developed nations. This increased average paternal age has led to concerns about adverse effects of advanced paternal age on sperm quality, assisted reproductive outcomes, and the health of the offspring conceived by older fathers. This review discusses the association between advanced paternal age and sperm parameters, assisted reproduction success rates, and offspring health.

Importance of a semen analysis report for determining the relationship between SCSA sperm DNA fragmentation index and assisted reproductive technology pregnancy rate

In the past, semen parameters have been the primary diagnostic criteria used to establish male infertility. However, with the exception of sperm motility, which is known to be linked to rates of in vitro fertilization success, these parameters are generally unreliable at accurately predicting the potential fertility of a couple. More recent research has suggested that sperm DNA fragmentation index (DFI) may be a more robust and reliable means of predicting assisted reproductive outcomes. The present study aimed to assess the relationship between sperm motility, sperm DFI, and rates of clinical pregnancy by analyzing data from 3000 couples dealing with infertility. Using the most recent semen analysis reports available from male partners in these couples, we assessed these parameters and found that the lower the sperm DFI value, the higher the rate of clinical pregnancy. When we assessed the correlation between sperm DFI, sperm motility, and clinical pregnancy, we observed a strong negative correlation between DFI and motility, but observed no significant relationship between sperm motility and pregnancy rates. These results thus indicate that the measurement of DFI via a sperm chromatin structure assay (SCSA) may be a valuable tool for analyzing semen in order to better predict and improve pregnancy rates in infertile couples.

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.

Bio-Functional Sperm Parameters: Does Age Matter?

The evaluation of biofunctional sperm parameters can explain some cases of idiopathic male infertility. Among these, sperm DNA fragmentation (fDNA) is the most studied biofunctional sperm parameter. Mitochondrial membrane potential (MMP) correlates positively with sperm motility, the evaluation of sperm apoptosis by flow cytometry allows us to identify a population of spermatozoa not recognizable at the optical microscopy and finally, lipid peroxidation (LP) and mitochondrial superoxide levels measurements are rational oxidative stress indices. Male age seems to affect sperm concentration and sperm fDNA. For these reasons, this study was undertaken to evaluate the correlation, if any, between male age and biofunctional sperm parameters evaluating their possible impact on fDNA. To accomplish this, MMP, degree of chromatin compactness, sperm apoptosis/vitality, fDNA, LP, and mitochondrial superoxide levels were evaluated by flow cytometry in a cohort of 874 men. A significant negative correlation was found between age and the percentage of alive spermatozoa (r = -0.75, p < 0.05). The percentage of spermatozoa with low MMP (L-MMP) correlated positively with the percentage of spermatozoa with abnormal chromatin compactness (r = 0.24, p < 0.05). Spermatozoa with abnormal chromatin compactness and L-MMP correlated negatively with the percentage of alive spermatozoa (r = 0.83, p < 0.05) and positively with spermatozoa with PS externalization (r = 0.13, p < 0.01). The percentage of alive spermatozoa correlated negatively with both the percentage of spermatozoa with PS externalization (r = 0.24, p < 0.01) and of the spermatozoa with fDNA (r = 0.10, p < 0.05). Spermatozoa with PS externalization correlated positively with the percentage of spermatozoa with fDNA (r = 0.09, p < 0.05). Spermatozoa with LP correlated positively with the percentage of spermatozoa with increased mitochondrial superoxide (r = 0.11, p < 0.01) In conclusion, these findings in a large number of men suggest that age, mitochondrial damage, and alteration of chromatin compactness could activate the apoptotic cascade which could result in an increased fDNA rate.

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.

Evidence that fertility trades off with early offspring fitness as males age

Models of ageing predict that sperm function and fertility should decline with age as sperm are exposed to free radical damage and mutation accumulation. However, theory also suggests that mating with older males should be beneficial for females because survival to old age is a demonstration of a male's high genetic and/or phenotypic quality. Consequently, declines in sperm fitness may be offset by indirect fitness benefits exhibited in offspring. While numerous studies have investigated age-based declines in male fertility, none has taken the integrated approach of studying age-based effects on both male fertility and offspring fitness. Here, using a cohort-based longitudinal study of zebrafish (Danio rerio), we report a decline in male mating success and fertility with male age but also compensating indirect benefits. Using in vitro fertilization, we show that offspring from older males exhibit superior early survival compared to those from their youngest counterparts. These findings suggest that the high offspring fitness observed for the subset of males that survive to an old age (approx. 51% in this study) may represent compensating benefits for declining fertility with age, thus challenging widely held views about the fitness costs of mating with older males.

JG. The effects of male age on sperm DNA damage: an evaluation of 2,178 semen samples

OBJECTIVE

This study aimed to evaluate the effects of male age on sperm DNA damage.

METHODS

This cross-sectional study included semen samples collected from 2,178 men seen at an infertility clinic. For DNA integrity analysis, the proportions of spermatozoa showing DNA fragmentation (TUNEL assay), abnormal chromatin packaging/underprotamination (chromomycin A3), abnormal mitochondrial membrane potential (MMP/MitoTracker Green), and apoptosis (annexin V) were recorded. For group comparisons, enrolled subjects were divided into three groups based on their ages: ≤35 years; 36-44 years; and ≥45 years. The associations between age and sperm parameters were assessed using Spearman's rank correlation coefficient.

RESULTS

Although aging did not affect sperm apoptosis (p>.05), sperm DNA fragmentation and MMP deteriorated significantly with age (p<.05). Chromatin packaging/protamination improved significantly with age (p<.05).

CONCLUSION

Sperm DNA fragmentation worsened with age and was apparently associated with mitochondrial damage. The age-related increase in sperm DNA damage suggests that delaying childbearing, not only in women but also in men, might jeopardize a couple's reproductive capacity. The increase seen in chromatin packaging might represent a protective feature for DNA. However, additional studies must be performed to confirm the results concerning chromatin packaging/protamination.

Paternal age and assisted reproductive technology: problem solver or trouble maker?

In our society, the number of couples with advanced reproductive age seeking fertility treatment is increasing steadily. While the negative effect of female age on assisted reproductive technology (ART) outcomes is well established, the impact of paternal age needs to be clarified. We reviewed the current literature to determine whether advanced paternal age affects the results of ART and the health of resulting offspring. We found that the published literature is overall supportive of a positive association between advanced paternal age (>40 years) and semen quality deterioration. However, the existing evidence does not corroborate nor discard the influence of advanced paternal age on ART outcomes. Similarly, the effect of paternal age on the health of ART offspring remains equivocal, although data from naturally-conceived children clearly indicates that advanced paternal age increases the frequency of genetic, neurodevelopmental, and psychiatric diseases in the progeny. Noteworthy, the current literature is limited and subjected to bias due to the impact of maternal age as a critical confounder. Health care providers should discuss with concerned couples the available options to counteract the possible negative influence of advanced paternal age on ART outcomes and health of resulting offspring. These include identification and treatment of underlying conditions with potential negative long-term effects on fertility, sperm freezing at a young age, and use of antioxidant supplements for men at risk of excessive oxidative stress. Aged male partner from couples undergoing ART, in particular men of 50 years and older, should consider use of preimplantation genetic testing as a means to detect embryo abnormalities and select euploid embryos for transfer to the uterine cavity.

Investigation on the origin of sperm morphological defects: oxidative attacks, chromatin immaturity, and DNA fragmentation

DNA fragmentation can be deleterious on spermatozoon morphology but the pathogenesis of teratozoospermia associated with DNA breaks is not fully understood, even if oxidative attacks and defects in chromatin maturation are hypothesized. Therefore, this study is one of the first to clarify on the underlying hypothesizes behind such observations. The objectives of our study were to assess the role of oxidative attacks in DNA damage pathogenesis in ejaculated spermatozoa from patients with isolated teratozoospermia. We aimed to assess the correlation of DNA breaks with morphologically abnormal spermatozoa, as well as ROS level and impairment chromatin condensation. A total of 90 patients were divided into two groups, men with isolated teratozoospermia (n = 60) and men with normal semen parameters (n = 30) as controls. DNA fragmentation was evaluated by TUNEL assay; chromatin immaturity was studied using acridine orange and toluidine blue staining. We evaluated the ability of spermatozoa to produce reactive oxygen species with nitro blue tetrazolium staining. Patient with teratozoospermia when compared to fertile men showed significantly higher rates of semen ROS production, sperm hypocondensated chromatin, denaturated DNA, and fragmented DNA. All these parameters were positively correlated with abnormal sperm morphology. The studied DNA integrity markers were also correlated with ROS production. Fragmented DNA is the main pathway leading to morphology defects in the sperm. In fact, impaired chromatin compaction may induce DNA breaks and free radicals, which can break the DNA backbone indirectly, by reducing protamination and disulphide bond formation, as oxidative attack appears to be the major cause of poor semen morphology.

Paternal age: Negative impact on sperm genome decays and IVF outcomes after 40 years

This study assessed sperm quality declining on relation to paternal age and its impact on in vitro fertilization (IVF) outcomes in order to estimate the APA (Advanced Paternal Age) cutoff. For this, 83 couples undergoing IVF treatment for male factor infertility were enrolled. The women age was ≤39 years, whereas the men were divided in two groups: APA (n = 41; age ≥ 40 years) and young (Y) (n = 42; age < 40 years). Conventional semen parameters (volume, concentration, motility, vitality, and morphology) were analyzed in the collected sperm samples. Furthermore, sperm genome decays (SGD) was assessed by TUNEL assay (DNA fragmentation), aniline blue staining (chromatin decondensation), and fluorescent in situ hybridization (aneuploidy). No significant difference was found concerning the conventional semen parameters between APA and Y groups. Conversely, SGD analysis showed increased DNA fragmentation; chromatin decondensation and sperm aneuploidy rates in the APA group (respectively, 41%, 43%, and 14% vs. 25%, 23%, and 4% in Y group). IVF outcomes also were affected by paternal age as indicated by the rates of cancelled embryo transfers, clinical pregnancy and miscarriage in the two groups APA and Y (29%, 17%, and 60% vs. 10%, 32%, and 42%). Finally, statistical analysis of the results suggests that the age of 40 should be considered as the APA cutoff during ART attempts.

A systematic review and meta-analysis to determine the effect of sperm DNA damage on in vitro fertilization and intracytoplasmic sperm injection outcome

Sperm DNA damage is prevalent among infertile men and is known to influence natural reproduction. However, the impact of sperm DNA damage on assisted reproduction outcomes remains controversial. Here, we conducted a meta-analysis of studies on sperm DNA damage (assessed by SCSA, TUNEL, SCD, or Comet assay) and clinical pregnancy after IVF and/or ICSI treatment from MEDLINE, EMBASE, and PUBMED database searches for this analysis. We identified 41 articles (with a total of 56 studies) including 16 IVF studies, 24 ICSI studies, and 16 mixed (IVF + ICSI) studies. These studies measured DNA damage (by one of four assays: 23 SCSA, 18 TUNEL, 8 SCD, and 7 Comet) and included a total of 8068 treatment cycles (3734 IVF, 2282 ICSI, and 2052 mixed IVF + ICSI). The combined OR of 1.68 (95% CI: 1.49–1.89; P < 0.0001) indicates that sperm DNA damage affects clinical pregnancy following IVF and/or ICSI treatment. In addition, the combined OR estimates of IVF (16 estimates, OR = 1.65; 95% CI: 1.34–2.04; P < 0.0001), ICSI (24 estimates, OR = 1.31; 95% CI: 1.08–1.59; P = 0.0068), and mixed IVF + ICSI studies (16 estimates, OR = 2.37; 95% CI: 1.89–2.97; P < 0.0001) were also statistically significant. There is sufficient evidence in the existing literature suggesting that sperm DNA damage has a negative effect on clinical pregnancy following IVF and/or ICSI treatment.

The impact of male age on embryo quality: a retrospective study using time-lapse imaging

OBJECTIVE

This study aimed to correlate male age with embryo morphokinetic parameters on D3 considering the timing and the exact moment of embryo cleavage.

METHODS

Time-lapse imaging was used to produce an ideal cleavage curve for the embryos analyzed. The percentage of embryos under the curve was analyzed and correlated with male age.

RESULTS

32.6% of the embryos from patients aged 28-33 years were under the curve; 36.2% of the embryos from patients aged 34-39 years were under the curve; 41.3% of the embryos from patients aged 40-45 years were under the curve; and 26.3% of the embryos fro patients aged 46-57 years were under the curve.

CONCLUSIONS

a statistically non-significant decrease was observed in the percentage of embryos under the optimal cleavage curve on D3 in the group of men aged between 40 and 45 years. Further studies looking into embryos in the blastocyst stage (D5 or D6) are required.

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.

HBA score in relation to donor semen profiles and live birth rates: a preliminary study

We sought to determine whether sperm donor selection could be improved by using the hyaluronan binding assay (HBA) score to predict live birth rates (LBRs) in donor insemination treatments. Thirty donor samples were included: five fresh samples to assess whether HBA score is affected by cryopreservation and 25 frozen samples from donors whose sperm gave rise to known live births, divided into three groups, with success rates ≥50%, <50-33% and <33%, to examine whether HBA score correlates with LBRs. Correlations with semen analysis parameters, as well as donor demographic factors, known causes of patient subfertility and/or the type of treatment provided were also assessed. There was no significant difference in the mean HBA score pre- and post-cryopreservation (p = 0.998) nor in the HBA score of the three different outcome groups (p = 0.89). HBA score was not significantly affected by other semen analysis parameters (r²=0.394, p = 0.127) or any of the other examined factors. This was the first study to investigate HBA score for cryopreserved donor samples with known LBRs. HBA score was not correlated with LBRs in this small pilot study. Larger studies are required to validate HBA score as a tool for sperm donor selection and predictor of LBRs.

Effect of male age on oxidative stress markers in human semen

This study conducted a comprehensive analysis of oxidative stress markers in human semen within the context of assisted reproductive technology (ART) and investigated if these markers varied according to male age. 148 semen samples were collected from 139 men presenting at Concept Fertility Centre, Western Australia, from 2009 to 2012. Semen analyses were performed and demographic information including smoking status and abstinence period was collected. Reactive oxygen species production, lipid peroxidation, oxidative DNA damage (8-hydroxy-2′-deoxyguanosine (8-OHdG)), total antioxidant capacity and DNA fragmentation ( terminal deoxynucleotidyl transferase-mediated deoxyuridine diphosphate nick-end labelling) were measured as markers of oxidative stress. Semen parameters and oxidative stress markers were compared against age as a continuous variable, and between males <40 and males ≥40 years of age. Older males aged ≥40 years exhibited higher levels of sperm oxidative DNA damage (8-OHdG) compared to younger males ( p = 0.029), but no other oxidative stress marker significantly varied with age. An age-related decrease in sperm concentration ( p = 0.011) and motility ( p = 0.015) was observed after processing. Lower sperm concentration and reduced motility pre- and post-semen processing were significantly correlated with elevated oxidative DNA damage (all p < 0.001). Our results suggest that oxidative stress may be an important mediator between male age and fertility. This is concerning within the context of an ageing ART cohort, as sperm oxidative DNA damage is associated with a range of suboptimal fertility outcomes.

Influence of sperm fertilising concentration, sperm selection method and sperm capacitation procedure on the incidence of numerical chromosomal abnormalities in IVF early bovine embryos

The occurrence of numerical chromosomal aberrations, widely described as a major cause of mortality in in vitro-produced (IVP) embryos, has been linked to several factors. In the present study we investigated the effect of sperm fertilising concentration and semen handling (sperm selection and capacitation) before IVF on the rate of numerical chromosomal abnormalities in bovine embryos. In all, 466 IVP cattle embryos were karyotyped throughout three sequential experiments, analysing the effects of sperm fertilising concentration (0.1, 1.0 or 10×10(6) spermatozoa mL(-1)), selection method (unselected or Percoll-selected spermatozoa) and capacitation medium (bovine serum albumin (BSA), heparin or their combination). The percentage of normal (diploid) and aberrant (haploid, polyploid or aneuploid) embryos was noted in each experiment. The rate of numerical chromosomal abnormalities was mainly affected by sperm fertilising concentration (P<0.01) and, to a lesser extent, by the sperm capacitation medium (P<0.05). Polyploidy and haploidy rates were only affected by sperm fertilising concentration (P<0.05). Interestingly, the sperm selection technique used in the present study did not reduce the incidence of chromosome abnormalities in IVP cattle embryos (P>0.05). Finally, aneuploidy rates were not affected during the experiments (P>0.05), which suggests that they are not related to sperm-related factors. On the basis of these results, we conclude that sperm fertilising concentration is the 'paternal' key factor that affects the rate of numerical chromosomal abnormalities in IVP bovine embryos. By making small adjustments to fertilising protocols, the rate of cytogenetically aberrant embryos can be markedly reduced.

Sperm selection in natural conception: what can we learn from Mother Nature to improve assisted reproduction outcomes?

BACKGROUND

In natural conception only a few sperm cells reach the ampulla or the site of fertilization. This population is a selected group of cells since only motile cells can pass through cervical mucus and gain initial entry into the female reproductive tract. In animals, some studies indicate that the sperm selected by the reproductive tract and recovered from the uterus and the oviducts have higher fertilization rates but this is not a universal finding. Some species show less discrimination in sperm selection and abnormal sperm do arrive at the oviduct. In contrast, assisted reproductive technologies (ART) utilize a more random sperm population. In this review we contrast the journey of the spermatozoon in vivo and in vitro and discuss this in the context of developing new sperm preparation and selection techniques for ART.

METHODS

A review of the literature examining characteristics of the spermatozoa selected in vivo is compared with recent developments in in vitro selection and preparation methods. Contrasts and similarities are presented.

RESULTS AND CONCLUSIONS

New technologies are being developed to aid in the diagnosis, preparation and selection of spermatozoa in ART. To date progress has been frustrating and these methods have provided variable benefits in improving outcomes after ART. It is more likely that examining the mechanisms enforced by nature will provide valuable information in regard to sperm selection and preparation techniques in vitro. Identifying the properties of those spermatozoa which do reach the oviduct will also be important for the development of more effective tests of semen quality. In this review we examine the value of sperm selection to see how much guidance for ART can be gleaned from the natural selection processes in vivo.

Effects of increased paternal age on sperm quality, reproductive outcome and associated epigenetic risks to offspring

Over the last decade, there has been a significant increase in average paternal age when the first child is conceived, either due to increased life expectancy, widespread use of contraception, late marriages and other factors. While the effect of maternal ageing on fertilization and reproduction is well known and several studies have shown that women over 35 years have a higher risk of infertility, pregnancy complications, spontaneous abortion, congenital anomalies, and perinatal complications. The effect of paternal age on semen quality and reproductive function is controversial for several reasons. First, there is no universal definition for advanced paternal ageing. Secondly, the literature is full of studies with conflicting results, especially for the most common parameters tested. Advancing paternal age also has been associated with increased risk of genetic disease. Our exhaustive literature review has demonstrated negative effects on sperm quality and testicular functions with increasing paternal age. Epigenetics changes, DNA mutations along with chromosomal aneuploidies have been associated with increasing paternal age. In addition to increased risk of male infertility, paternal age has also been demonstrated to impact reproductive and fertility outcomes including a decrease in IVF/ICSI success rate and increasing rate of preterm birth. Increasing paternal age has shown to increase the incidence of different types of disorders like autism, schizophrenia, bipolar disorders, and childhood leukemia in the progeny. It is thereby essential to educate the infertile couples on the disturbing links between increased paternal age and rising disorders in their offspring, to better counsel them during their reproductive years.

Consistent age-dependent declines in human semen quality: a systematic review and meta-analysis

Reduced fertility typically occurs among women in their late 30s, but increasing evidence indicates that advanced paternal age is associated with changes in reproduction as well. Numerous studies have investigated age-based declines in semen traits, but the impact of paternal age on semen parameter values remains inconclusive. Using data from 90 studies (93,839 subjects), we conducted a systematic review and meta-analysis to quantify the effect of male age on seven ejaculate traits (semen volume, sperm concentration, total sperm count, morphology, total motility, progressive motility and DNA fragmentation). Age-associated declines in semen volume, percentage motility, progressive motility, normal morphology and unfragmented cells were statistically significant and results generally seemed to be robust against confounding factors. Unexpectedly, sperm concentration did not decline with increasing male age, even though we found that sperm concentration declined over time. Our findings indicate that male age needs more recognition as a potential contributor to the negative pregnancy outcomes and reduced offspring health associated with delayed first reproduction. We suggest that greater focus on collection of DNA fragmentation and progressive motility in a clinical setting may lead to better patient outcomes during fertility treatments of aging couples.

Infertile men older than 40 years are at higher risk of sperm DNA damage

BACKGROUND

The effect of paternal age on semen quality is controversial. In this retrospective study, the aim was to investigate the effects of advancing age on sperm parameters including reactive oxygen species (ROS), total antioxidant capacity (TAC) and sperm DNA damage in infertile men. We also examined whether paternal age >40 y is associated with higher risk of sperm DNA damage.

METHODS

A total of 472 infertile men presenting for infertility were divided into 4 age groups: group A: patients ≤ 30 y; group B: patients 31- 40 y, group C: ≤ 40 y and group D: patients >40 y. The following tests were performed - semen analysis according to WHO 2010 criteria, seminal ROS by chemiluminescence, TAC by colorimetric assay and sperm DNA damage by TUNEL assay - and the results were compared amongst the 4 age groups.

RESULTS

There was no statistical difference in conventional semen parameters, TAC and ROS with advancing paternal age as well as between different age groups. However, a significant negative association was noted between sperm DNA damage and advancing paternal age. Men >40 y showed higher levels of sperm DNA damage (24.4 ± 18.5%) compared to younger men (<30 y; 16.7 ± 11.2%; p <0.05).

CONCLUSIONS

Infertile men over the age of 40 y have a greater percentage of sperm DNA fragmentation compared to infertile men aged 40 y and below. Advanced paternal age (>40 y) may increase the risk of sperm DNA damage in infertile men.

Sperm deoxyribonucleic acid damage in normozoospermic men is related to age and sperm progressive motility

OBJECTIVE

To evaluate sperm DNA fragmentation in normozoospermic male partners of couples undergoing infertility evaluation.

DESIGN

Retrospective cohort study.

SETTING

Clinical andrology laboratory.

PATIENT(S)

A total of 1,974 consecutive normozoospermic men selected from a larger cohort of 4,345 consecutive, nonazoospermic men presenting for infertility evaluation.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Clinical parameters, conventional semen parameters, and sperm DNA fragmentation assessed by flow cytometry-based TUNEL assay and reported as percent sperm DNA fragmentation (%SDF).

RESULT(S)

The mean (± SD) %SDF and the proportion of men with high %SDF (>30%) were significantly lower in the normozoospermic compared with the entire cohort of 4,345 evaluable infertile men (17.6% ± 10.1% vs. 20.7% ± 12.4% and 11% vs. 20%, respectively). In the group of 1,974 normozoospermic men, %SDF was positively correlated with paternal age (r = 0.17) and inversely correlated with progressive motility (r = -0.26). In the subset of normozoospermic men with sperm parameters above the 50th percentile (≥ 73 × 10(6) sperm/mL, ≥ 55% progressive motility, and ≥ 14% normal forms, World Health Organization 2010 guidelines), 5% (4 of 83) had elevated %SDF (>30%).

CONCLUSION(S)

In this large cohort of normozoospermic men presenting for infertility evaluation, DNA fragmentation level is related to sperm motility and paternal age, and 11% of these men have high levels of sperm DNA fragmentation. Furthermore, the data indicate that a nonnegligible proportion (5%) of normozoospermic men with high-normal sperm parameters may also have significant sperm DNA fragmentation.

Comparative analysis of three sperm DNA damage assays and sperm nuclear protein content in couples undergoing assisted reproduction treatment

STUDY QUESTION

Is there an association between sperm DNA damage, measured by three different assays, sperm nuclear protein content and clinical outcomes in assisted reproduction treatment (ART)?

SUMMARY ANSWER

Sperm DNA damage measured by terminal deoxynucleotidyltransferase-mediated dUTP nick-end labelling (TUNEL) and the Comet assay were significantly associated with ART outcomes in our single institution study.

WHAT IS KNOWN ALREADY

Abnormal protamine expression is known to be associated with sperm DNA damage and male infertility. A number of studies have shown a significant relationship between sperm DNA damage and ART outcomes. To date, there are no large studies providing direct comparisons of DNA damage tests within the same study population. Thus, the prognostic value for each method remains unknown.

STUDY DESIGN, SIZE, DURATION

Cross-sectional study of 238 men from infertile couples undergoing ART at the University Center for Reproductive Medicine, Utah, USA, between April 2011 and March 2013.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Sperm from men undergoing ART were tested for DNA damage using the alkaline Comet assay, TUNEL and flow cytometric chromatin evaluation (FCCE) assays. Histone retention was analysed using the aniline blue staining method, whereas protamine content (proteins P1 and P2) and ratio were analysed using acid urea gel electrophoresis. The prognostic value of each sperm DNA test to predict clinical pregnancy was calculated.

MAIN RESULTS AND THE ROLE OF CHANCE

Histone retention was associated with sperm DNA damage (P < 0.001), reduced embryo quality (P = 0.005) and clinical pregnancies (P < 0.001). The mean percentage of sperm with DNA damage was significantly higher in sperm from non-pregnant couples compared with that from pregnant couples, as measured by TUNEL assay (15.04 ± 1.16% versus 8.79 ± 0.56%; P < 0.001) and alkaline Comet assay (72.79 ± 2.49% versus 55.86 ± 2.29%; P < 0.001). There was no association between clinical pregnancies and DNA fragmentation index measured by FCCE (12.97 ± 1.46 versus 14.93 ± 1.65; P = 0.379). Of the protamine parameters analysed, only the P1/P2 ratio was associated with sperm count (P = 0.013), men's age (P = 0.037), maturity (P = 0.049) and blastocyst quality (P = 0.012). Histone retention and sperm DNA damage measured by Comet and TUNEL assays were associated with fertilization rate (P < 0.05), embryo quality (P < 0.05) and implantation rate (P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

A potential drawback of this study is that it is cross-sectional. Generally in such studies there is more than one variable that could cause the effect. Analysing sperm is one part of the equation; there are also a number of female factors that have the potential to influence ART outcomes. Therefore, given the large and well-established role of female factors in infertility, normal sperm DNA integrity and protamination do not necessarily ensure clinical pregnancy in ART. Thus, female factors can reduce the prognostic value of sperm DNA tests. Further, our use of native semen instead of prepared sperm may have iatrogenically increased the DNA damage.

WIDER IMPLICATIONS OF THE FINDINGS

Alteration in sperm nuclear protein affects sperm DNA integrity. Further, with the current dataset, TUNEL and Comet assays appeared more predictive of ART success than FCCE.

STUDY FUNDING/COMPETING INTEREST(S)

No personal or direct financial support has been received for any of this work. The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Which isolated sperm abnormality is most related to sperm DNA damage in men presenting for infertility evaluation

BACKGROUND

Sperm DNA damage is common in infertile men and is associated with poor semen parameters but the impact of an isolated sperm abnormality on sperm DNA damage has not been studied.

OBJECTIVE

To evaluate sperm DNA damage in a large cohort of infertile men with isolated sperm defects.

DESIGN, SETTING AND PARTICIPANTS

Retrospective study of 1084 consecutive, non-azoospermic infertile men with an isolated sperm defect: isolated oligozoospermia (iOligo), isolated asthenozoospermia (iAstheno) or isolated teratozoospermia (iTerato).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We examined and compared clinical parameters, conventional semen parameters and %sperm DNA fragmentation (%SDF, assessed by flow cytometry-based Terminal deoxynucleotidyl transferase-mediated dUTP Nick End-Labeling assay) in the three groups of men.

RESULTS AND LIMITATIONS

The mean (±SD) %SDF was significantly higher in the iAstheno compared to the iOligo and iTerato groups (25.0 ± 14.0 vs. 19.2 ± 11.6 and 20.7 ± 12.1 %, respectively, P < 0.0001). Similarly, the proportion of men with high %SDF (>30 %) was significantly higher in the iAstheno compared to the iOligo and iTerato groups (31 % vs. 18 % and 19 %, respectively, P < 0.0001). In the group of 713 men with iAstheno, %SDF was positively correlated with paternal age (r = 0.20, P < 0.0001) and inversely correlated with %progressive motility (r = -0.18, P < 0.0001). In the subset of 218 men with iTerato, %SDF was also positively correlated with paternal age (r = 0.15, P = 0.018) and inversely correlated with %progressive motility (r = -0.26, P = 0.0001).

CONCLUSIONS

In this large cohort of infertile men with isolated sperm abnormalities, we have found that the sperm DNA fragmentation level is highest in the men with sperm motility defects and that 31 % of these men have high levels of sperm DNA fragmentation. The data indicate that poor motility is the sperm parameter abnormality most closely related to sperm DNA damage.

Mechanical processing of hyperviscous semen specimens can negatively affect sperm DNA fragmentation

INTRODUCTION

The present study compared the DNA fragmentation in human sperm samples with reduced, physiological, and increased viscosity in order to evaluate whether the process used to reduce viscosity (expulsion of semen through a needle and syringe) alters significantly sperm DNA fragmentation.

METHODS

The seminal parameters of semen samples from 123 patients were evaluated and classified according to their viscosity. Samples with increased viscosity were submitted to a process of expulsion of semen through a 10-mL syringe and an 18-gauge (18G) needle to reduce the seminal viscosity. The DNA fragmentation of all samples was analysed using TUNEL assay (Terminal deoxynucleotidyl transferase mediated dUTP Nick-end labelling assay); in samples with increased viscosity, the fragmentation was assessed before and after the process of expulsion with syringe and needle.

RESULTS

There was no difference in DNA fragmentation between groups with different viscosity (P = 0.857). A significantly increase in sperm DNA fragmentation after expulsion of hyperviscous semen through the syringe was observed (P = 0.035).

CONCLUSION

There was no difference in DNA fragmentation rate between samples with reduced, increased and physiological viscosities; however, the physical process of expulsion of semen through a syringe and needle increased sperm DNA fragmentation.

A qualitative study of Ottawa university students' awareness, knowledge and perceptions of infertility, infertility risk factors and assisted reproductive technologies (ART)

BACKGROUND

Awareness of infertility risk factors is an essential first step to safeguard future fertility. Whereas several studies have examined university students' awareness of female fertility and related risk factors, the topic of male infertility has not been well examined. The objective of this study was to assess young men and women's awareness, knowledge and perceptions of infertility, male and female infertility risk factors and assisted reproductive technologies (ART).

METHODS

Semi-structured interviews were conducted in 2008 with a multi-ethnic sample of sixteen male and twenty-three female Ottawa university students, followed by qualitative data analysis to identify major themes. Interview topics included awareness of male and female infertility risk factors, infertility diagnosis/treatments and personal options in the event of future infertility.

RESULTS

Participants were generally familiar with infertility as a biomedical health problem, could identify sex-specific risk factors but overestimated fertility of women in their thirties and ART success rates. Reproductive health knowledge gaps and confusion of the physiological life-stage of menopause with infertility were apparent. Most participants would pursue in vitro fertilization or international adoption in the event of personal infertility. Some participants wished to use a 'natural' approach and were concerned with potential side effects of ART-related medications.

CONCLUSIONS

The general awareness of infertility in young adults is promising and supports the potential uptake for health promotion of fertility preservation. This study underscores the continued need for comprehensive sexual and reproductive health education and promotion for adolescents and young adults.

High prevalence of isolated sperm DNA damage in infertile men with advanced paternal age

BACKGROUND

Sperm DNA damage is associated with male infertility, lower pregnancy rates and pregnancy loss.

OBJECTIVE

The primary aim of our study was to evaluate the prevalence of sperm DNA damage in younger and older men with normozoospermia.

DESIGN, SETTING AND PARTICIPANTS

We obtained semen from 277 consecutive non-azoospermic men presenting for sperm DNA testing.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The main outcome measures included sperm % DNA fragmentation index (%DFI, using sperm chromatin structure assay), sperm concentration, motility and morphology, and, paternal age.

RESULTS AND LIMITATIONS

Sperm % DFI was positively correlated with paternal age (r = 0.20, P < 0.001) and inversely correlated % progressive motility (r = -0.16, P = 0.01). Sperm %DFI was significantly higher in older (≥40 years) compared to younger (<40 years) normozoospermic men (17 ± 13 vs. 12 ± 8, respectively P = 0.008), whereas, sperm concentration, progressive motility and morphology were not significantly different in these two groups. Moreover, the prevalence of high levels of sperm DNA damage (>30 % DFI) was significantly higher in older compared to younger normozoospermic men (17 % vs. 3 %, respectively, P < 0.001).

CONCLUSION

The data indicate that a conventional semen analysis can often fail to detect a defect in spermatogenesis (high %DFI) in older men and suggest that infertile couples with advanced paternal age, including those with normal semen parameters, should consider sperm DNA testing as part of the couple evaluation.

The utility of sperm DNA damage assay using toluidine blue and aniline blue staining in routine semen analysis

OBJECTIVE

The aim of the present study was to examine the relationship among male age, strict morphology, and sperm chromatin structure and condensation.

METHODS

Sperm samples from a total of 100 men underwent semen analysis, and sperm chromatin structure and condensation were assessed with toluidine blue (TB) and aniline blue (AB) tests.

RESULTS

Prevalence of strict morphology of less than 4%, and abnormal sperm chromatin structure and condensation did not show any statistically significant differences according to male age (p=0.605, p=0.235, and p=0.080). No significant correlation was demonstrated among age of male partners, strict morphology, and abnormal sperm chromatin structure using TB and AB tests. However, abnormal sperm chromatin condensation was positively associated with sperm chromatin structure (r=0.594, p=0.000) and showed negative correlation with strict morphology (r=-0.219, p=0.029).

CONCLUSION

The tests for sperm chromatin condensation showed a significant association with strict morphology. Further study is needed to elucidate the relationship between clinical outcome and sperm chromatin tests.

Processes involved in assisted reproduction technologies significantly increase sperm DNA fragmentation and phosphatidylserine translocation

Sperm preparation techniques in assisted reproduction technologies (ART) are potential generators of exogenous stresses that cause additional DNA damage. DNA fragmentation tests, such as the sperm chromatin structure assay, involve freezing sperm samples in the absence of cryoprotectant. Thermal, oxidative stress (OS) and freezing are detrimental to sperm DNA fragmentation and phosphatidylserine (PS) translocation. The primary aim of this study was to subject mature sperm to environmental insults that normally occur during ART. We tested the hypotheses that OS, thermal stress and freeze-thawing caused sperm nuclear and membrane damage and that a positive correlation exists between PS translocation and DNA fragmentation. Sperm DNA integrity deteriorates in semen samples from men with advancing age and a sperm concentration of <15 m ml(-1) . The significant increase in sperm DNA fragmentation at 37 °C after merely 1 h is important clinically as semen liquefaction and short-term sperm storage in an ART cycle involve incubating samples at this temperature. Freezing without a cryoprotectant significantly increases the level of sperm nuclear damage, so it is important not to freeze neat semen prior to DNA fragmentation testing. This study highlights the importance of minimising the production of exogenous stresses during sperm preparation in ART.