Global decline in semen quality: ignoring the developing world introduces selection bias

Associations between Sperm Epigenetic Age and Semen Parameters: An Evaluation of Clinical and Non-Clinical Cohorts

The well-documented relationship between chronological age and the sperm methylome has allowed for the construction of epigenetic clocks that estimate the biological age of sperm based on DNA methylation, which we previously termed sperm epigenetic age (SEA). Our lab demonstrated that SEA is positively associated with the time taken to achieve pregnancy; however, its relationship with semen parameters is unknown. A total of 379 men from the Longitudinal Investigation of Fertility and Environment (LIFE) study, a non-clinical cohort, and 192 men seeking fertility treatment from the Sperm Environmental Epigenetics and Development Study (SEEDS) were included in the study. Semen analyses were conducted for both cohorts, and SEA was previously generated using a machine learning algorithm and DNA methylation array data. Association analyses were conducted via multivariable linear regression models adjusting for BMI and smoking status. We found that SEA was not associated with standard semen characteristics in SEEDS and LIFE cohorts. However, SEA was significantly associated with higher sperm head length and perimeter, the presence of pyriform and tapered sperm, and lower sperm elongation factor in the LIFE study (p < 0.05). Based on our results, SEA is mostly associated with defects in sperm head morphological factors that are less commonly evaluated during male infertility assessments. SEA shows promise to be an independent biomarker of sperm quality to assess male fecundity.

Oxidative Stress and Toxicity in Reproductive Biology and Medicine: A Comprehensive Update on Male Infertility Volume II - Conclusion

Infertility is a globally under-recognized public health problem significantly impacting individual health and socioeconomics affecting millions of couples. The reasons for infertility are manifold and not only include many couples decision to postpone having children but also diseases (e.g., diabetes, infections, or varicocele), lifestyle (e.g., obesity), and environmental factors (e.g., bisphenol A, DTT or dioxin). In the pathology of many causes of infertility, oxidative stress plays a significant role as reactive oxygen species (ROS) exert significant detrimental effects. On the other hand, a small amount of ROS is essential to trigger physiological events such as capacitation. Therefore, a fine balance between oxidation and reduction has to be maintained. Apart from treating the underlying disease or correcting the cause of the infertility, oxidative stress can be treated by antioxidant supplementation. Since plants and their extracts contain numerous phytochemicals which exhibit antioxidant activity, many people tend to use herbal products. Alternatively, isolated antioxidants such as vitamin C or E are also used. However, when using purified antioxidants, it is essential that the redox balance is maintained to avoid a "reductive stress" situation, which is as harmful as oxidative stress.

Simplified sperm testing devices: a possible tool to overcome lack of accessibility and inconsistency in male factor infertility diagnosis. An opportunity for low- and middle- income countries

Background

Manual semen assessment (MSA) is a key component in a male’s fertility assessment. Clinicians rely on it to make diagnostic and treatment decisions. When performed manually, this routine laboratory test is prone to variability due to human intervention which can lead to misdiagnosis and consequently over- or under- treatment. For standardisation, continuous training, quality control (QC) programs and pricy Computer-Assisted Sperm Analysis (CASA) systems have been proposed, yet, without resolving intra- and inter-laboratory variability. In response, promising simplified sperm testing devices, able to provide cost-effective point-of-care male infertility diagnosis are prospected as a plausible solution to resolve variability and increase access to sperm testing.

Materials and methods

A throughout literature research for semen testing, sperm analysis, smart-phone assisted semen analysis, ‘at-home’ semen testing, male infertility, infertility in developing countries, infertility in low- and middle-income countries (LMIC) and quantitative sperm analysis was performed. A total of 14 articles, specific to ‘at-home’ simplified sperm assessment, were included to treat the core subject.

Results

Continuous training and consistent QC, are sine qua none conditions to achieve accurate and comparable MSA. Compliance does not rule-out variability, nevertheless. Emerging simplified sperm assessment devices are an actual alternative to resolve the lack of standardisation and accessibility to sperm analysis. YO ® , SEEM ® , and ExSeed ® are commercially available, user-friendly smartphone-based devices which can accurately measure volume, sperm concentration (millions/ml) and total motile sperm count. More broadly, by cost-effectiveness, availability, accuracy and convenient application, these devices could effectively select patients for first-line artificial reproduction treatments such as intrauterine insemination.

Conclusions

Accuracy and cost-effectiveness make smart-phone based sperm testing devices a practical and realistic solution to overcome variability in MSA. Importantly, these tools represent an actual opportunity to standardise and improve male subfertility diagnosis and treatment, especially in LMIC. However, before clinical application is possible, guidelines, further testing with special attention on accuracy in washed sperm, availability, cost-benefit and reliability are required.

Perspectives of Nanoparticles in Male Infertility: Evidence for Induced Abnormalities in Sperm Production

Advancement in the field of nanotechnology has prompted the need to elucidate the deleterious effects of nanoparticles (NPs) on reproductive health. Many studies have reported on the health safety issues related to NPs by investigating their exposure routes, deposition and toxic effects on different primary and secondary organs but few studies have focused on NPs’ deposition in reproductive organs. Noteworthy, even fewer studies have dealt with the toxic effects of NPs on reproductive indices and sperm parameters (such as sperm number, motility and morphology) by evaluating, for instance, the histopathology of seminiferous tubules and testosterone levels. To date, the research suggests that NPs can easily cross the blood testes barrier and, after accumulation in the testis, induce adverse effects on spermatogenesis. This review aims to summarize the available literature on the risks induced by NPs on the male reproductive system.

Repeated administrations of Mn3O4 nanoparticles cause testis damage and fertility decrease through PPAR-signaling pathway

Potential health hazards of nanomaterials on male reproductive system have received raising concerns. Even though Mn₃O₄ nanoparticles (Mn₃O₄-NPs) is highly effective in clinical diagnostic and therapeutic applications of human disease, its potential toxic effect on the male reproductive system has not been reported. In this study, the testis damage and fertility decrease of male rats were conducted to testify the experimental reproductive injury induced by Mn₃O₄-NPs. After repeated tail vein injection with 10 mg/kg/week Mn₃O₄-NPs for 0, 60 and 120 days, Mn₃O₄-NPs accumulated in the testes resulted in oxidative stress and disorder of normal serum sex hormones. Experiments in vivo and in vitro indicated that mitochondria-mediated cell apoptosis were triggered via oxidative stress, demonstrated by the upregulation of malondialdehyde (MDA) and the depolarization of mitochondrial membrane potential. Notably, Mn₃O₄-NPs significantly resulted in a reduction of the quantity/quality of sperm and finally caused astonishing fertility decrease. Our preliminary result implied that the application of Mn₃O₄-NPs could be a double-edged sword and careful consideration should be given to the clinical uses.

Exposure to PbSe Nanoparticles and Male Reproductive Damage in a Rat Model

PbSe nanoparticles (PbSe-NPs) attract ever-growing interest owing to their great promise in various fields. However, potential toxic effects of PbSe-NPs on male reproductive systems have not been reported. This study aimed to determine whether early-life exposure to PbSe-NPs could affect male reproductive systems and other related health effects in rats. The male rats were intraperitoneally injected with 10 mg/kg/week PbSe-NPs for 60 days followed by a series of reproductive-related analyses. We found that the nanoparticles could accumulate in testes in a size-dependent manner. Furthermore, accumulation of PbSe-NPs resulted in oxidative stress and disorder of normal serum sex hormones. Endoplasmic reticulum and mitochondria-mediated cell apoptosis were triggered via oxidative stress, as shown by upregulation of cytoplasmic Cyt-c, Bax, cleaved Caspase-3, GRP78, and Caspase-12. Notably, PbSe-NP administration led to reduction in the quantity and quality of sperm, which caused a great fertility decrease. In contrast, released Pb²⁺ from PbSe-NPs did not result in any testis toxicity and fertility declines. These results demonstrate that PbSe-NPs could cause severe reproductive toxicity in a size-dependent manner and these toxic effects should be responsible for PbSe-NPs themselves rather than released Pb²⁺. The application of PbSe-NPs might be a double-edged sword, and corresponding measures should be taken before use.

Semen quality of young men in Switzerland: a nationwide cross-sectional population-based study

BACKGROUND

Sperm counts have been steadily decreasing over the past five decades with regional differences in the Western world. The reasons behind these trends are complex, but numerous insights indicate that environmental and lifestyle factors are important players.

OBJECTIVE

To evaluate semen quality and male reproductive health in Switzerland.

MATERIALS AND METHODS

A nationwide cross-sectional study was conducted on 2523 young men coming from all regions of Switzerland, recruited during military conscription. Semen volume, sperm concentration, motility, and morphology were analyzed. Anatomy of the genital area and testicular volume was recorded. Testicular cancer incidence rates in the general population were retrieved from Swiss regional registries.

RESULTS

Median sperm concentration adjusted for period of sexual abstinence was 48 million/mL. Comparing with the 5th percentile of the WHO reference values for fertile men, 17% of men had sperm concentration below 15 million/mL, 25% had less than 40% motile spermatozoa, and 43% had less than 4% normal forms. Disparities in semen quality among geographic regions, urbanization rates, and linguistic areas were limited. A larger proportion of men with poor semen quality had been exposed in utero to maternal smoking. Furthermore, testicular cancer incidence rates in the Swiss general population increased significantly between 1980 and 2014.

DISCUSSION

For the first time, a systematic sampling among young men has confirmed that semen quality is affected on a national level. The median sperm concentration measured is among the lowest observed in Europe. No specific geographical differences could be identified. Further studies are needed to determine to what extent the fertility of Swiss men is compromised and to evaluate the impact of environmental and lifestyle factors.

CONCLUSION

A significant proportion of Swiss young men display suboptimal semen quality with only 38% having sperm concentration, motility, and morphology values that met WHO semen reference criteria.

CASA-Mot in mammals: an update

Sperm motility is one of the most widely used parameters of sperm quality. Computer-aided sperm motility analysis (CASA-Mot) systems were developed to reduce the subjectivity of sperm motility assessment, and have had broad scientific and practical acceptance. In this review, the sources of variation and current applications of this technology and its relationships with other sperm quality tests are described in detail. Despite remarkable advances in the technique, there is still great need for standardisation in many species, and the numerous factors that affect the results make it difficult to provide universally accepted criteria for classifying semen samples based on sperm motility characteristics. The main fields for CASA-Mot include the study of male fertility and pathologies, evaluation of the effects of physical and chemical agents, improvement of epidemiological survey studies, more precise calculation of seminal doses for farm animals, realisation of basic studies about sperm function, improvement of sperm technologies such as cryopreservation and quality control analysis. Numerous relationships have been established between CASA-Mot and other sperm quality tests, although most of these parameters are complementary. Future CASA-Mot systems will probably be able to integrate several sperm quality parameters with motility.

Male Infertility Problem: A Contemporary Review on Present Status and Future Perspective

Semen quality plays a pivotal role in maintaining healthy fertilizing ability of spermatozoa. Male infertility is a rising global problem with an increasing declining in male semen quality among men living in Africa, Europe, North American, and Asia. Though the sperm acquire proactive mechanisms during spermatogenesis and their epididymal maturation, they still remain viable for toxic insult. Declining semen quality is a major contributor to infertility. Studies have postulated that different factors, such as exposure to pesticides, industrial chemicals, heavy metals, obesity, alcoholism, tobacco smoking, sedentary lifestyles, poor nutrient intake, oxidative stress, physiological factors, genetic factors can influence male fertility. Routine semen analysis and assays for sperm chromatin integrity are the most widely utilized and best studied adjunctive diagnostics in male infertility. Over the years, scientists have developed different treatment options for male infertility. Male infertility with known etiology can be treated successfully, but other causes like genetic factors require pragmatic approaches. This article summarizes protective mechanisms of spermatogenesis, causes, diagnosis, and both modern and traditional treatment approaches of male infertility. Further, this article highlights present issues and direction for future exploration of the male infertility problem.

Ubiquitous Flame-Retardant Toxicants Impair Spermatogenesis in a Human Stem Cell Model

Sperm counts have rapidly declined in Western males over the past four decades. This rapid decline remains largely unexplained, but exposure to environmental toxicants provides one potential explanation for this decline. Flame retardants are highly prevalent and persistent in the environment, but many have not been assessed for their effects on human spermatogenesis. Using a human stem cell-based model of spermatogenesis, we evaluated two major flame retardants, hexabromocyclododecane (HBCDD) and tetrabromobisphenol A (TBBPA), under acute conditions simulating occupational-level exposures. Here we show that HBCDD and TBBPA are human male reproductive toxicants in vitro. Although these toxicants do not specifically affect the survival of haploid spermatids, they affect spermatogonia and primary spermatocytes through mitochondrial membrane potential perturbation and reactive oxygen species generation, ultimately causing apoptosis. Taken together, these results show that HBCDD and TBBPA affect human spermatogenesis in vitro and potentially implicate this highly prevalent class of toxicants in the decline of Western males' sperm counts.

Protective potential of royal jelly against cadmium-induced infertility in male rats

This study aimed to investigate the protective potential of Royal jelly (RJ) against cadmium (Cd)-induced testicular dysfunction in rats. Thirty-five adult male Wistar rats were assigned into five groups. G I; (control) injected intraperitoneally with saline, G II injected intraperitoneally with a single dose of CdCl₂ (1 mg/kg BW), G III received RJ (100 mg/kg BW/day) orally, G IV was pre-treated with RJ for 1 week then, treated with CdCl₂ , and G V was co-treated with RJ and CdCl₂ . After day 56, serum and tissue samples were collected and analysed. The results showed decreased serum testosterone, luteinising hormone (LH), follicle-stimulating hormone (FSH), superoxide dismutase, glutathione reductase, sperm motility and count while increased malondialdehyde, nitric oxide, tumour necrosis factor-α (TNF-α) and sperm abnormalities, along with a severely damaged seminiferous tubules epithelium with cytoplasmic and nuclear disruptions following Cd toxicity. Additionally, Cd stimulated testicular mRNA expression of TNF-α while inhibited those of steroidogenic acute regulatory protein, cytochrome P450 cholesterol side chain cleavage enzyme androgen binding protein, FSH-receptor, LH-receptor, androgen receptor, 3β-hydroxysteroid dehydrogenase (HSD), 17β-HSD, and cytochrome P450 17A1. These negative alterations of cadmium were greatly reduced by RJ treatment. This study concluded that RJ protects against Cd-induced testicular toxicity.

Semen Quality Assessment in Fertile Men in Madrid During the Last 3 Decades

OBJECTIVE

To evaluate semen quality of men with proven fertility in Spain over the last 3 decades.

METHODS

We conduct a retrospective analysis of ejaculate samples of 992 men between 1985 and 2009. All patients had proven fertility as demonstrated by fathering at least 2 children and a semen analysis performed before they underwent vasectomy. A standardized procedure was used for the semen analysis. Semen volume, total sperm count, sperm concentration, motility, and percentage of morphologically normal spermatozoa were assessed. Mean values were calculated by examining microscopic fields of 100 spermatozoa.

RESULTS

Statistically significant differences were found in all semen parameters analyzed. For the periods 1985-1990, 1990-2000, and 2000-2009, the mean (standard deviation [SD]) sperm concentration was 27.7 (22.97), 20.73 (14.79), and 20.18 (20.79) × 10(6) (P <.0001). The mean (SD) progressive motility for each period was 53.19 (20.35), 47.22 (15.84), and 40.57 (15.15; P <.0001). The mean (SD) normal-shaped spermatozoa for each period was 67.69 (10.24), 58.87 (14.67), and 51.02 (15.76; P <.0001). Multivariate analysis using a logistic regression model showed that age had no significant effect in the variation of semen parameters at the cut-points analyzed, except for normal forms at percentile 25 (P = .001). Multivariate analysis revealed a trend for decline of semen in sperm concentration, progressive and nonprogressive motility, and the percentage of morphologically normal spermatozoa (P = .001-.002).

CONCLUSION

Over the last 3 decades, a decline in semen quality was found in all the parameters analyzed in Spanish men with proven fertility.

Identification of optimal concentrations and incubation times for the study of in vitro effects of Pb in ram spermatozoa

In vitro effects of lead (Pb) on ram (Ovis aries) spermatozoa were studied to establish a threshold level that affects sperm function. Spermatozoa were incubated between 15 and 180 min with Pb concentrations ranging from 0 to 5,000 ng/mL. Sperm motility, acrosome integrity, membrane functionality and sperm viability were all negatively affected by Pb and incubation time. Acrosome integrity was linearly affected by Pb levels at an incubation time of 30 min, and 50 ng/mL was the lowest Pb level producing such effect. These experimental conditions can be appropriate for in vitro studies of the mechanisms of action of Pb on spermatozoa.