The effects of aging on semen parameters and sperm DNA fragmentation

Impact of aging on spermatogenic function and reproductive outcomes in repro57 heterozygous male mice: A model for age-related infertility

PURPOSE

This study aims to investigate the histological changes, sperm parameters, and their impact on embryo development rates and offspring numbers in advanced-age male repro57 heterozygous mice, corresponding to approximately 40 years of age in humans.

METHODS

Sperm parameters were assessed in both young and advanced-age repro57 heterozygous mice, as well as in young and advanced-age wild-type mice. Additionally, testis weight and histological analysis of seminiferous tubules were conducted to identify degenerative changes. Male mice from each group were mated with young wild-type females to compare offspring numbers, and in vitro fertilization (IVF) was used to evaluate fertilization and blastocyst formation rates.

RESULTS

No significant differences in sperm concentration and motility were observed between young and aged wild-type mice or between young wild-type and young repro57 heterozygous mice. However, advanced-age repro57 heterozygous mice exhibited significantly lower sperm parameters and testis weight compared to advanced-age wild-type mice. Histological analysis revealed increased Sertoli cell vacuolation in the seminiferous tubules of advanced-age repro57 heterozygous mice. Additionally, these advanced-age mice exhibited significantly lower blastocyst formation rates and produced fewer offspring compared to advanced-age wild-type mice.

CONCLUSION

Advanced reproductive aging in repro57 heterozygous male mice is associated with marked senescence-like degenerative changes, leading to a decline in offspring numbers, attributed to increased Sertoli cell vacuolation and diminished sperm quality.

Abnormal sperm tails correlate with the sperm DNA fragmentation index, irrespective of progressive motility, according to an analysis of 5125 semen reports

PURPOSE

Sperm progressive motility (PR) is correlated with the sperm DNA fragmentation index (SDF). Moreover, abnormalities in sperm tails are closely associated with the quality of sperm PR. However, the correlation of abnormal sperm tails with the SDF remains unknown.

METHODS

Routine semen examination was performed according to the World Health Organization guidelines with a computer-assisted semen analysis system. SDF analysis was conducted via the sperm chromatin structure assay method. Spearman correlation was used to test the correlation of the SDF with age and conventional semen parameters. The relationship between the SDF and abnormal tails was explored by binary logistic regression analysis, restricted cubic spline (RCS) analyses and subgroup analysis. ROC curves were used to assess the predictive capacity of age, abnormal tails and PR for the SDF.

RESULTS

The SDF was associated with sperm morphology, with a significant correlation observed with abnormal sperm tails (r = 0.491, P < 0.001). Binary regression analysis revealed that abnormal sperm tails were an independent influencing factor of the SDF. RCS analyses and Trend analysis suggested that as the number of abnormal sperm tails increased, the risk of an abnormal SDF also increased, and the trend was statistically significant (P for trend < 0.001). The ROC curve demonstrated that abnormal sperm tails had good discriminatory ability for the SDF (AUC: 0.757, P < 0.001).

CONCLUSION

Abnormal sperm tails are an independent influencing factor of the SDF, and a higher number of abnormal tails is associated with an increased risk of an abnormal SDF.

Modifiable life style factors and male reproductive health: a cross-sectional study in IVF clinic attendees in Ghana

Background

Male infertility is a significant global public health issue, with modifiable lifestyle factors such as smoking, obesity, and psychological stress contributing to impaired semen quality and hormonal dysregulation. This study investigates the relationships between modifiable lifestyle factors, reproductive hormones, and semen quality in Ghanaian males attending an IVF clinic.

Methods

A cross-sectional study was conducted with 212 male participants recruited from a fertility clinic in Ghana. Lifestyle factors were assessed using standardized questionnaires, and semen samples were analyzed following WHO guidelines. Hormonal profiles (LH, FSH, testosterone, estradiol) were measured using the enzyme-linked fluorescent assay (ELFA). Statistical analyses included Pearson's product-moment correlation and Bonferroni correction.

Results

Smoking and psychological stress were significantly associated with reduced sperm motility, viability, and concentration (p < 0.05). Elevated BMI correlated negatively with sperm concentration and testosterone levels (p < 0.05). Alcoholic bitters was linked to decreased semen quality, while caffeine consumption showed a positive association with progressive sperm motility.

Conclusion

Modifiable lifestyle factors, such as smoking, psychological stress, and increased body mass index (BMI), play a crucial role in male reproductive health by adversely affecting semen parameters and hormonal balance. These findings emphasize the need for public health interventions targeting modifiable behaviors to improve fertility outcomes.

Physical activity and male reproductive function

Fecundity is declining in humans, which is partly due to male infertility. Poor sperm parameters, the main contributors to male infertility, are associated with sedentary, unhealthy lifestyle and poor dietary habits. Long periods of sedentary work lead to visceral adiposity and persistently elevated scrotal temperatures, which adversely affect spermatogenesis. Apart from increasing scrotal temperatures, excessive visceral adiposity exacerbates adipocyte dysfunction with increased pro-inflammatory adipokine release, like leptin. These, together with the increased scrotal temperature, are responsible for the poor sperm quality. The importance of regular physical activity in male fertility remains a matter of debate, as not all forms of exercises have been found to benefit sperm function. Sperm parameters are, nevertheless, somewhat better in active than in sedentary men. It now appears that low-to-moderate intensity exercises are more beneficial for male reproductive health than high-intensity exercises, which have a negative effect on spermatozoa. Low-to-moderate intensity exercises, in general, improve the overall organ-system function in the body, improve the management of body weight and oxidative stress, consequently improving sperm parameters. The detrimental effects of high-intensity exercises on spermatozoa result from disruption in the hypothalamus-pituitary-gonadal-axis, raised testicular temperature and increased oxidative stress. It, therefore, seems that not all types of exercises are beneficial for male reproductive health. Although some low-to-moderate intensity exercises improve male reproductive function, there remains a need to identify the best form of low-to-moderate intensity exercises, particularly those that do not increase testicular temperature or oxidative stress, to help maintain normal body weight and male reproductive health.

The effects of vitamin E supplementation on sperm parameters, chromatin integrity, and gene expression before and after freezing in aged mice

OBJECTIVE

Some age-related testicular changes, such as Sertoli cell vacuolization and blood-testis barrier breakdown, reduce total sperm production and male fertility. Therefore, this study investigated the effect of vitamin E on restoring testicular function in aged mice. Sperm cryo-resistance was also assessed.

METHODS

Twenty-eight 48-week-old male Naval Medical Research Institute mice were divided into four groups for a daily gavage of vitamin E: the control group received distilled water, while the three treatment groups were administered 100, 200, and 400 mg/kg, respectively, for 4 weeks. Subsequently, semen analyses, DNA fragmentation index (DFI), and protamine deficiency tests were conducted. Testicular histology, tissue antioxidant enzyme activity, and gene expression levels were also assessed.

RESULTS

The two higher dosages of vitamin E were associated with a higher sperm count, greater progressive motility, and improved sperm morphology (p<0.05). These benefits were also evident after sperm freezing (p<0.05). Although chromatin abnormalities increased following vitrification, the treatment groups showed better outcomes (p<0.05). The tubular diameter, epithelium height, and luminal diameters remained unchanged with age. The tissue antioxidant capacity was greater in the groups receiving the high doses of vitamin E. Additionally, significant increases in inhibitor of DNA binding protein-4 (Id4) and GDNF family receptor alpha-1 (Gfra1) expression were observed in the higher vitamin E dosage groups, and promyelocytic leukemia zinc finger protein (Plzf) expression was notably present in the 400 mg/kg treatment group compared to the control group (p<0.05).

CONCLUSION

Antioxidant supplementation might enhance reproductive outcomes in aging males. The observed effects included improved sperm cryo-resistance, which is advantageous for future applications such as sperm freezing or fertility preservation.

Effect of paternal age on clinical outcomes of in vitro fertilization-embryo transfer cycles

Purpose

This study aimed to investigate the impact of paternal age > 40 years on clinical pregnancy and perinatal outcomes among patients undergoing in vitro fertilization treatment.

Methods

We selected 75 male patients (aged > 40 years) based on predefined inclusion and exclusion criteria. Propensity score matching was performed in a 1:3 ratio, resulting in a control group (aged ≤ 40 years) of 225 individuals. Various statistical tests, including the Mann-Whitney U test, Chi-square test, Fisher's exact test, and binary logistic regression, were used to analyze the association between paternal age and clinical outcomes.

Results

We found no statistically significant differences in semen routine parameters, clinical pregnancy outcomes, and perinatal outcomes between paternal aged > 40 and ≤ 40 years. However, in the subgroup analysis, the live birth rate significantly decreased in those aged ≥ 45 compared to those aged 41-42 and 43-44 years (31.25% vs. 69.23% and 65%, respectively; all p < 0.05). Additionally, the clinical pregnancy rate was significantly lower among those aged ≥ 45 than among those aged 41-42 (43.75% vs. 74.36%; p=0.035).

Conclusion

Paternal age ≥ 45 years was associated with lower live birth and clinical pregnancy rates.

Secondary azoospermia after a successful natural pregnancy: a primary prospective study

BACKGROUND

To date, there is a lack of studies conducted on males with secondary azoospermia as a potential cause of male infertility who had previously fathered children through natural conception. The current study aims to investigate the potential causes of secondary azoospermia as a presentation of male infertility as well as the prognostic factors that can impact sperm retrieval rate (SRR) while undergoing microdissection testicular sperm extraction (microTESE).

RESULTS

Thirty two patients were recruited from the andrology outpatient clinic from August 2023 till January 2024. The mean age of the patients was sixty-two years old. All patients had varicoceles. Twenty seven patients (84%) had palpable varicocele grade 2 and 3 on both sides. Further multivariate logistic regression analysis of the significant factors in the univariate regression revealed that younger age (OR 0.7, 95% C.I. 0.7-1.0, p = 0.03) and having a history of coronary artery disease (CAD) were predictable factors for negative TESE outcome (OR 123.1, 95% C.I. 3.2-4748.5, P = 0.01).

CONCLUSION

It appears that the etiopathogenesis of secondary azoospermia are multifactorial. Varicocele and CAD are major factors to be considered. Future studies should be implemented deploying larger pools of patients suffering from the same condition to affirm the findings of this primary study.

Influence of Age, Obesity, Smoking, Sleep duration, and Sleep Quality on Concentration, Morphology, and Sperm Motility: A Cross-Sectional Study

BACKGROUND

Age, smoking, sleep duration, sleep quality, and obesity are risk factors that can affect the amount of sperm concentration, morphology, and motility. The aim of this study is to assess the lifestyle effects: of age, smoking, sleep duration, sleep quality, and obesity on the amount of concentration, morphology, and motility of sperm.

MATERIALS AND METHODS

The study utilized an analytical observational approach with a cross-sectional design. The study subjects comprised 70 male partners of infertile couples admitted to the Sekar Fertility Clinic at the Dr. Moewardi General Hospital between March and August 2022. The study assessed variables including age, body mass index (BMI), smoking status, sleep duration, sleep quality, sperm concentration, sperm morphology, and sperm motility. Furthermore, the data were analyzed using univariate, bivariate, and multivariate methods with SPSS 25 software.

RESULTS

The research findings demonstrate that obesity is significantly associated with abnormal sperm concentration [odds ratio (OR)=40.07, confidence interval (CI)=3.90-411.67, P=0.002]. Furthermore, moderate or heavy smoking is significantly associated with abnormal sperm concentration (OR=17.45, CI=1.83-166.15, P=0.013) and sleep quality with severe disorders (OR=5.73, CI=1.12-29.21, P=0.036). Moreover, obesity is significantly associated with abnormal sperm motility (OR=12.97, CI=2.66-63.15, P=0.002), while moderate or heavy smoking (OR=5.89, CI=1.23- 28.20, P=0.026) and poor sleep duration (OR=6.21, CI=1.43-26.92, P=0.015) also exhibit significant associations with abnormal sperm motility. However, no significant findings were observed regarding sperm morphology.

CONCLUSION

The findings of this study indicate that obesity, moderate or heavy smoking, and sleep quality have statistically significant effects on sperm concentration, while obesity, moderate or heavy smoking, and sleep duration have statistically significant effects on sperm motility. However, no statistically significant influence was observed on sperm morphology. Further research with larger sample sizes and more diverse populations is needed to validate these findings and explore other potential factors that may impact male fertility.

The Correlation of Paternal Age on Semen Parameters in Assisted Reproduction: A Retrospective Study in Qassim, Saudi Arabia

INTRODUCTION

In the past, fertility concerns have predominantly revolved around the effect of a woman's age on the quality of her eggs and the success of her pregnancy. While men generally retain their ability to father children throughout their lives, there is evidence suggesting a decline in natural conception rates as paternal age increases. A growing body of research indicates a potential link between advanced paternal age (APA) and various adverse outcomes, including changes in sperm genetics, reduced conception rates, higher rates of miscarriage, lower live birth rates, and even long-term health consequences in offspring. However, it remains unclear whether there is an association between APA and the effectiveness of assisted reproductive technology (ART). This study aims to shed light on the relationship between APA and semen parameters.

METHODOLOGY

This is a retrospective, descriptive study analyzing data from electronic medical records of men undergoing ART at a fertility clinic in Saudia Arabia (2017-2022). Men aged 21-60 with at least one semen analysis and no missing data/hormonal treatment were included. Data on age and semen parameters (count, motility, and morphology) were extracted and analyzed using Jeffreys's Amazing Statistics Program (JASP; University of Amsterdam, Amsterdam, Netherlands) (descriptive statistics, Spearman's rank correlation).

RESULTS

Analysis of 1506 men undergoing ART revealed a mean age of 37 years (SD=6.94) and a mean sperm count of 55.0 million/mL (SD=46.05). The correlation between age and sperm count indicates a minimal association (r=0.075, p<0.01); moderate positive correlations were observed between sperm count and motility (r=0.406); count and morphology (r=0.543); and motility and morphology (r=0.458).

CONCLUSION

Age may not be a major factor in overall sperm parameters for this population, but a strong positive correlation was observed between sperm count, motility, and normal morphology. These findings suggest that these semen parameters are interconnected, with higher sperm counts potentially indicating better overall sperm quality.

Small extracellular vesicles from young plasma reverse age-related functional declines by improving mitochondrial energy metabolism

Recent investigations into heterochronic parabiosis have unveiled robust rejuvenating effects of young blood on aged tissues. However, the specific rejuvenating mechanisms remain incompletely elucidated. Here we demonstrate that small extracellular vesicles (sEVs) from the plasma of young mice counteract pre-existing aging at molecular, mitochondrial, cellular and physiological levels. Intravenous injection of young sEVs into aged mice extends their lifespan, mitigates senescent phenotypes and ameliorates age-associated functional declines in multiple tissues. Quantitative proteomic analyses identified substantial alterations in the proteomes of aged tissues after young sEV treatment, and these changes are closely associated with metabolic processes. Mechanistic investigations reveal that young sEVs stimulate PGC-1α expression in vitro and in vivo through their miRNA cargoes, thereby improving mitochondrial functions and mitigating mitochondrial deficits in aged tissues. Overall, this study demonstrates that young sEVs reverse degenerative changes and age-related dysfunction, at least in part, by stimulating PGC-1α expression and enhancing mitochondrial energy metabolism.

Sperm HSP70: may not be an age-dependent gene but is associated with field fertility in Bali bulls (Bos sondaicus)

This study aimed to analyze the characteristics of the HSP70 gene and protein in spermatozoa of Bali bulls of different age groups and to examine its potential as a biomarker determining bull fertility. This study used frozen semen produced from six Bali bulls divided into two groups based on age (≤ 9 years and ≥ 12 years). Parameters of frozen semen quality analyzed included sperm motility and kinetics using computer-assisted semen analysis, sperm morphological defects using Diff-Quick staining, acrosome integrity using FITC-PNA staining, and DNA fragmentation using acridine orange staining. HSP70 gene expression characterization was analyzed using qRT-PCR, and HSP70 protein abundance was analyzed using enzyme immunoassays. Fertility field data were obtained by analyzing the percentage conception rate for each bull based on the artificial insemination service data contained in the Indonesian-integrated system of the National Animal Health Information System (iSIKHNAS). The results showed significant differences (P<0.05) in total and progressive motility, morphological defects of the neck and midpiece, and tail of sperm, and acrosome integrity between the age groups of Bali bulls. HSP70 gene expression and protein abundance showed no significant differences (P>0.05) in different age groups. HSP70 gene expression correlated with fertility rate (P<0.05). Age affected several semen quality parameters but did not affect HSP70 gene expression and protein abundance. The HSP70 gene molecule could be a biomarker that determines the fertility of Bali bulls.

Elevated sperm DNA fragmentation is correlated with an increased chromosomal aneuploidy rate of miscarried conceptus in women of advanced age undergoing fresh embryo transfer cycle

Background

Male sperm DNA fragmentation (SDF) may be associated with assisted reproductive technology (ART) outcomes, but the impact of SDF on the occurrence of aneuploid-related miscarriage remains controversial.

Methods

Genome-wide single-nucleotide polymorphism-based chromosomal microarray analysis was performed on 495 miscarried chorionic villus samples undergone IVF/ICSI treatment from the Reproductive Medicine Center of the First Affiliated Hospital of Zhengzhou University. SDF was assessed using sperm chromatin structure assay. Patients were divided into four groups according to embryo transfer cycle type and maternal age, and the correlation between SDF and chromosome aberration was analyzed. A receiver operating characteristic (ROC) curve was utilized to find the optimal threshold.

Results

Total chromosomal aneuploidy rate was 54.95%, and trisomy was the most common abnormality (71.32%). The chromosomally abnormal group had higher SDF than the normal group (11.42% [6.82%, 16.54%] vs. 12.95% [9.61%, 20.58%], P = 0.032). After grouping, elevated SDF was significantly correlated with an increasing chromosome aneuploidy rate only in women of advanced age who underwent fresh embryo transfer (adjusted odds ratio:1.14 [1.00-1.29], adjusted-P = 0.045). The receiver operating characteristic curve showed that SDF can predict the occurrence of chromosomal abnormality of miscarried conceptus in this group ((area under the curve = 0.76 [0.60-0.91], P = 0.005), and 8.5% was the optimum threshold. When SDF was ≥ 8.5%, the risk of such patients increased by 5.76 times (adjusted odds ratio: 6.76 [1.20-37.99], adjusted-P = 0.030).

Conclusion

For women of advanced maternal age undergoing fresh embryo transfer, older oocytes fertilized using sperm with high SDF in IVF/ICSI treatment might increase the risk of chromosomal abnormality in miscarried conceptus.

Factors associated with embryo mosaicism: a systematic review and meta-analysis

PURPOSE

Evaluate which factors are involved in the increased rate of mosaicism in embryos.

METHODS

A systematic review and meta-analysis was performed. After an exhaustive search of the literature, a total of seven papers were included in the analysis. In addition, data collected from IVF cycles performed in our fertility clinic were also analysed. Day of biopsy, embryo quality, maternal and paternal age and seminal quality were the chosen factors to be studied.

RESULTS

The results of the meta-analysis show that neither embryo quality nor seminal quality were related to mosaic embryo rate (OR: 1.09; 95% CI: 0.94-1.28 and OR: 1.10; 95% CI: 0.87-1.37, respectively). A positive association was observed for the variable "biopsy day" with embryos biopsied at day 6 or 7 having the highest rate of mosaicism (OR: 1.06; 95% CI: 1.01-1.11). In opposite to what happens with aneuploidy rate, which increases with maternal age, embryo mosaicism is higher in younger women (<34 years) rather than in older ones (≥34 years) (OR: 0.95; 95% CI: 0.92-0.98). However, for the "paternal age" factor, no association with mosaicism was found (OR: 1.04; 95% CI: 0.90-1.21).

CONCLUSIONS

With the present study, we can conclude that the factors related to the presence of mosaicism in embryos are the embryo biopsy day and maternal age. The rest of the studied factors showed no significant relationship with mosaicism. These results are of great importance as knowing the possible causes leading to mosaicism helps to improve the clinical results of reproductive treatments.

Single-cell RNA sequencing reveals the local cell landscape in mouse epididymal initial segment during aging

BACKGROUND

Morphological and functional alterations in aging reproductive organs result in decreased male fertility. The epididymis functions as the transition region for post-testicular sperm maturation. And we have previously demonstrated that the epididymal initial segment (IS), a region of the reproductive tract essential for sperm maturation and capacitation, undergoes considerable histological changes and chronic immune activation in mice during aging. However, the local aging-associated cellular and molecular changes in the aged epididymal IS are poorly understood.

RESULTS

We conducted single-cell RNA sequencing analysis on the epididymal IS of young (3-month-old) and old (21-month-old) mice. In total, 10,027 cells from the epididymal IS tissues of young and old mice were obtained and annotated. The cell composition, including the expansion of a principal cell subtype and Ms4a4b^HiMs4a6b^Hi T cells, changed with age. Aged principal cells displayed multiple functional gene expression changes associated with acrosome reaction and sperm maturation, suggesting an asynchronous process of sperm activation and maturation during epididymal transit. Meanwhile, aging-related altered pathways in immune cells, especially the "cell chemotaxis" in Cx3cr1^Hi epididymal dendritic cells (eDCs), were identified. The monocyte-specific expression of chemokine Ccl8 increased with age in eDCs. And the aged epididymal IS showed increased inflammatory cell infiltration and cytokine secretion. Furthermore, cell-cell communication analysis indicated that age increased inflammatory signaling in the epididymal IS.

CONCLUSION

Contrary to the general pattern of lower immune responses in the male proximal genital tract, we revealed an inflammaging status in mouse epididymal initial segment. These findings will allow future studies to enable the delay of male reproductive aging via immune regulation.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

Trends in semen parameters of infertile men in South Africa and Nigeria

There are conflicting reports on trends of semen parameters from different parts of the globe. However, in recent times there is dearth of information on the trend in Sub-Saharan countries. Therefore, in this study we aimed at determining the trends in semen parameters in Nigeria and South Africa between 2010 and 2019. A retrospective study of semen analyses of 17,292 men attending fertility hospitals in Nigeria and South Africa in 2010, 2015 and 2019. Patients who had undergone vasectomy and those who had a pH less than 5 or greater than 10 were excluded from this study. The following variables were assessed: ejaculate volume, sperm concentration, progressive motility, total progressively motile sperm count (TPMSC), total sperm count, and normal sperm morphology. Between 2010 and 2019, significant trends of decreasing values were observed in normal sperm morphology (- 50%), and the ejaculatory volume (- 7.4%), indicating a progressive deterioration of the values in both countries. In Nigeria, there were significant decreases in progressive motility (- 87%), TPMSC (- 78%), and sperm morphology (- 55%) between 2010 and 2019 (P < 0.001). Spearman`s rank correlation revealed significant negative associations between age and morphology (ρ =  - 0.24, P < 0.001), progressive motility (ρ =  - 0.31. P < 0.001), and TPMSC (ρ =  - 0.32, P < 0.001). Patients in South Africa were younger than those from Nigeria, with also a significantly higher sperm morphology, sperm concentration, progressive motility, total sperm count and TPMSC. Our findings provide a quantitative evidence of an alarming decreasing trend in semen parameters in Nigeria and South Africa from 2010 to 2019. It also proves that astheno- and teratozoospermia are the leading causes of male infertility in these regions. In addition to this, it also shows empirically that semen parameters decrease with advancement in age. These findings are the first report of temporal trends in semen parameters in Sub-Saharan countries, necessitating a thorough investigation on the underlying factors promoting this worrisome decline.

The effect of aging on semen parameters in normozoospermic men: A cross-sectional study

Background

Semen parameters change with age and are reported differently worldwide.

Objective

This retrospective cross-sectional study aimed to investigate the semen quality pattern among aging men and the age thresholds for semen parameters.

Materials and Methods

The records of men who had normal semen parameters from January 2015-June 2020 were retrospectively evaluated for andrological outpatient at Samsun Training and Research hospital and Gazi hospital in Samsun, Turkey. Adult men meeting the inclusion criteria were divided into 3 groups of I) 18-29 yr (n = 629), II) 30-39 yr (n = 775), and III) 40-49 yr (n = 190). Correlations between age and sperm parameters were then analyzed.

Results

A total of 1594 men were enrolled in the study. Significant differences were observed in total sperm numbers, total motility rates, progressive motility rates, nonprogressive motility rates, normal morphology rates, mean semen volume, and sperm concentrations. The parameters of total sperm number, progressive motility rate, and normal morphology rate were significantly higher in group I than in the other 2 groups (p < 0.001, p < 0.001, and p < 0.001, respectively) and in group II compared to group III (p = 0.001, p = 0.003, and p < 0.001), respectively. Mean semen volume and total motility rate were significantly higher in group I than in the other groups (p = 0.001 and p < 0.001, respectively). However, no difference was observed between group II and group III (p = 0.61 and p = 0.04, respectively).

Conclusion

Age has a significant impact on semen parameters capable of affecting male fertility, particularly total sperm numbers, the progressive motility rate, and the normal morphology rate.

Optimizing pregnancy outcomes in intrauterine insemination cycles by stratifying pre-wash total motile count and patient-specific factors: a patient counseling tool

PURPOSE

The purpose of this study is to clarify which pre-wash total motile count are associated with improved clinical pregnancy rate (CPR) and live birth rate (LBR) based on maternal age, AMH level, stimulation regimen, and infertility diagnosis.

METHODS

This was a retrospective cohort study of first completed IUI cycles at two academic fertility centers from 5/2015 to 9/2019. Cycles were stratified by pre-wash TMC, maternal age, AMH level, stimulation regimen, and infertility diagnosis. The primary outcome was CPR and secondary outcomes were live birth and miscarriage.

RESULTS

One thousand one hundred fifty-four cycles were analyzed. Of the 162 cycles that resulted in a CPR (14.0%), most had an insemination TMC > 20 million. Compared to TMC > 20 million, there was no difference in CPR or LBR for lower TMC categories, excluding the TMC < 2 million group, in which there were no pregnancies. When TMC was stratified by deciles, there was also no difference in CPR and LBR, including within the lowest decile (TMC 0.09-8.6 million). Younger age and higher ovarian reserve parameters were associated with higher pregnancy and LBR when stratified by TMC. There was no difference in pregnancy and LBR when considering different stimulation protocols.

CONCLUSIONS

Our data suggest that pregnancy and LBR are equivalent above a TMC of 2 million. Data stratified by TMC and patient parameters can be used to counsel patients pursuing ART.

Testicular aging, male fertility and beyond

Normal spermatogenesis and sperm function are crucial for male fertility. The effects of healthy testicular aging and testicular premature aging on spermatogenesis, sperm function, and the spermatogenesis microenvironment cannot be ignored. Compared with younger men, the testis of older men tends to have disturbed spermatogenic processes, sperm abnormalities, sperm dysfunction, and impaired Sertoli and Leydig cells, which ultimately results in male infertility. Various exogenous and endogenous factors also contribute to pathological testicular premature aging, such as adverse environmental stressors and gene mutations. Mechanistically, Y-chromosomal microdeletions, increase in telomere length and oxidative stress, accumulation of DNA damage with decreased repair ability, alterations in epigenetic modifications, miRNA and lncRNA expression abnormalities, have been associated with impaired male fertility due to aging. In recent years, the key molecules and signaling pathways that regulate testicular aging and premature aging have been identified, thereby providing new strategies for diagnosis and treatment. This review provides a comprehensive overview of the underlying mechanisms of aging on spermatogenesis. Furthermore, potential rescue measures for reproductive aging have been discussed. Finally, the inadequacy of testicular aging research and future directions for research have been envisaged to aid in the diagnosis and treatment of testicular aging and premature aging.

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.

Sperm DNA integrity and male infertility: a narrative review and guide for the reproductive physicians

Background and Objective

Conventional semen analysis (SA) remains an essential tool in the initial male fertility evaluation and subsequent follow-up. However, it neither provides information about the functional status of spermatozoa nor addresses disorders such as idiopathic or unexplained infertility (UI). Recently, assessment of sperm DNA fragmentation (SDF) has been proposed as an extended sperm test that may help overcome these inherent limitations of basic SA. In this review, we aim to: (I) discuss the pathophysiological aspects of SDF, including natural repair mechanisms, causes, and impact on reproductive outcomes; (II) explain different assessment tools of SDF, and describe potential therapeutic options to manage infertile men with high SDF; and (III) analyse the strengths, weaknesses, opportunities and threats (SWOT) of current research on the topic.

Methods

This review was constructed from original studies, systematic reviews and meta-analyses that were published over the years up until August 2021, related to the various aspects of SDF.

Key Content and Findings

Different mechanisms lead to high SDF, including defective chromatin packaging, apoptosis, and seminal oxidative stress. The relevance of sperm DNA integrity to male fertility/infertility has been supported by the frequent observation of high levels of SDF in infertile men, and in association with risk factors for infertility. Additionally, high SDF levels have been inversely correlated with the outcomes of natural pregnancy and assisted reproduction. Terminal deoxynucleotidyl transferase dUTP nick end labelling, sperm chromatin structure assay, sperm chromatin dispersion, and Comet assay are four commonly used assays for measurement of SDF. Addressing lifestyle risks and underlying conditions, antioxidants, hormonal therapy, and advanced sperm selection techniques have all been proposed as potential therapeutic options to lower SDF.

Conclusions

The sum of literature provides evidence of detrimental effects of high SDF on both natural and assisted fertility outcomes. Standardization of the techniques used for assessment of SDF and their incorporation into the work up of infertile couples may have significant implications on the future management of a selected category of infertile men with high SDF.

Evaluating the Contribution of Oocyte, Sperm, and Uterus in Determining the Outcome of Intracytoplasmic Sperm Injection - A Retrospective Observational Comparative Study on Intracytoplasmic Sperm Injection using Own Oocytes and Donor Oocytes

Context

Several studies have assessed the contribution of oocyte, sperm, and endometrium on the outcome of intracytoplasmic sperm injection (ICSI) separately. This study assesses the relative contribution of oocyte, sperm, and uterus in achieving clinical pregnancy (CP) through ICSI by comparing own and third-party ICSI cycles.

Aim

The aim of the study is to evaluate and compare the strength of contribution of oocyte, sperm, and uterus in achieving CP through ICSI.

Settings and Design

This retrospective observational study of ICSI cycles for 20 months including 1000 embryo transfers (ETs).

Methodology

Subjects were divided into two groups, Group 1 - ICSI with own oocytes (550 ETs) and Group 2 - ICSI with donor oocytes (450 ETs). Both the groups had 3 subgroups - a (husband sperm, transferred to self), b (donor sperm, transferred to self), c (husband sperm, transferred to a gestational surrogate). CP rate (CPR) as a major outcome was studied in the groups and subgroups.

Statistical Analysis

CPR was compared between various subgroups using Z-test and Chi-square of significance of difference between proportions. A P < 0.05 was taken as the level of statistical significance.

Results

CPR in subgroup 1a < 35 years, 1a ≥35 years, and 2a was 42.98%, 26.21%, and 40.92%, respectively (P = 0.001). CPR was compared between 2a and 2c (40.92%, 56.5%, P = 0.044) and between 2a and 2b (40.92%, 42.11%, P = 0.866). Implantation rate was highest in Group 2c (34.88%) compared to other subgroups.

Conclusion

The higher CPR in women <35 years undergoing ICSI with own oocytes than older women and a comparable CPR as that of recipients of donor oocytes suggests that age thereby oocyte quality is the strongest determining factor in achieving clinical pregnancy. Among oocyte recipients, higher CPR in surrogate uterus than patient uterus suggests that uterus/endometrium plays a considerable role, and comparable CPR between ICSI using husband sperm and donor sperm indicates that sperm quality might not play a major role in achieving CP.

Male subfertility and oxidative stress

To date 15% of couples are suffering from infertility with 45-50% of males being responsible. With an increase in paternal age as well as various environmental and lifestyle factors worsening these figures are expected to increase. As the so-called free radical theory of infertility suggests, free radicals or reactive oxygen species (ROS) play an essential role in this process. However, ROS also fulfill important functions for instance in sperm maturation. The aim of this review article is to discuss the role reactive oxygen species play in male fertility and how these are influenced by lifestyle, age or disease. We will further discuss how these ROS are measured and how they can be avoided during in-vitro fertilization.

Proteostasis in the Male and Female Germline: A New Outlook on the Maintenance of Reproductive Health

For fully differentiated, long lived cells the maintenance of protein homeostasis (proteostasis) becomes a crucial determinant of cellular function and viability. Neurons are the most well-known example of this phenomenon where the majority of these cells must survive the entire course of life. However, male and female germ cells are also uniquely dependent on the maintenance of proteostasis to achieve successful fertilization. Oocytes, also long-lived cells, are subjected to prolonged periods of arrest and are largely reliant on the translation of stored mRNAs, accumulated during the growth period, to support meiotic maturation and subsequent embryogenesis. Conversely, sperm cells, while relatively ephemeral, are completely reliant on proteostasis due to the absence of both transcription and translation. Despite these remarkable, cell-specific features there has been little focus on understanding protein homeostasis in reproductive cells and how/whether proteostasis is "reset" during embryogenesis. Here, we seek to capture the momentum of this growing field by highlighting novel findings regarding germline proteostasis and how this knowledge can be used to promote reproductive health. In this review we capture proteostasis in the context of both somatic cell and germline aging and discuss the influence of oxidative stress on protein function. In particular, we highlight the contributions of proteostasis changes to oocyte aging and encourage a focus in this area that may complement the extensive analyses of DNA damage and aneuploidy that have long occupied the oocyte aging field. Moreover, we discuss the influence of common non-enzymatic protein modifications on the stability of proteins in the male germline, how these changes affect sperm function, and how they may be prevented to preserve fertility. Through this review we aim to bring to light a new trajectory for our field and highlight the potential to harness the germ cell's natural proteostasis mechanisms to improve reproductive health. This manuscript will be of interest to those in the fields of proteostasis, aging, male and female gamete reproductive biology, embryogenesis, and life course health.

Phthalates in Albumin from Human Serum: Implications for Assisted Reproductive Technology

Albumin, a vital protein in cell culture systems, is derived from whole blood or blood products. The culture of human gametes and developing embryos for assisted reproduction (ART) uses albumin of human origin. Human serum albumin (HSA) is derived from expired blood obtained from blood banks. This blood has been stored in polyvinyl chloride bags made clear and flexible with di-2-ethylhexyl phthalate (DEHP). But DEHP can leach from the bags into stored blood and co-fractionate with HSA during albumin isolation. DEHP and its metabolite mono-ethylhexyl phthalate (MEHP), are known endocrine disruptors that are reported to have negative effects when directly supplemented in media for IVF using gametes from a variety of animals. Therefore, the contamination of ART media with DEHP and MEHP through HSA supplementation may have effects on the outcomes of ART procedures. While the embryology laboratory is strictly monitored to prevent a wide variety of contamination, phthalate contamination of HSA has not been broadly examined. This review outlines the function of HSA in ART procedures and the production of HSA from whole blood. Finally, the review highlights the effects of acute phthalate exposures on gametes during in vitro procedures.

Male-specific age estimation based on Y-chromosomal DNA methylation

Although DNA methylation variation of autosomal CpGs provides robust age predictive biomarkers, no male-specific age predictor exists based on Y-CpGs yet. Since sex chromosomes play an important role in aging, a Y-chromosome-based age predictor would allow studying male-specific aging effects and would also be useful in forensics. Here, we used blood-based DNA methylation microarray data of 1,057 males from six cohorts aged 15-87 and identified 75 Y-CpGs with an interquartile range of ≥0.1. Of these, 22 and six were significantly hyper- and hypomethylated with age (p(cor)<0.05, Bonferroni), respectively. Amongst several machine learning algorithms, a model based on support vector machines with radial kernel performed best in male-specific age prediction. We achieved a mean absolute deviation (MAD) between true and predicted age of 7.54 years (cor=0.81, validation) when using all 75 Y-CpGs, and a MAD of 8.46 years (cor=0.73, validation) based on the most predictive 19 Y-CpGs. The accuracies of both age predictors did not worsen with increased age, in contrast to autosomal CpG-based age predictors that are known to predict age with reduced accuracy in the elderly. Overall, we introduce the first-of-its-kind male-specific epigenetic age predictor for future applications in aging research and forensics.

Sperm DNA fragmentation and male fertility: a retrospective study of 5114 men attending a reproductive center

PURPOSE

The sperm DNA fragmentation index (DFI) was quantitatively measured and its relationship with age, semen quality, and infertility conditions was investigated.

METHODS

Semen routine test and sperm DFI were performed in 2760 infertile male and 2354 male whose spouse experienced at least one unexplained miscarriage to analyze the correlation between sperm DNA damage, semen routine parameters, and age.

RESULTS

Sperm DFI was significantly lower from patients whose wife experienced unexplained miscarriage compared to infertility males (p = 0.000). An inverse correlation between sperm DFI and sperm progressive motility was observed (r_s = - 0.465, p = 0.000) and sperm DFI was positively correlated with age (r_s = 0.255, p = 0.000). However, the correlation between sperm DFI and sperm concentration, semen volume, total sperm count, and motile sperm count were not proved.

CONCLUSIONS

Sperm DFI is an important indicator for evaluating the quality of semen. Sperm DNA integrity testing is preferentially recommended to those who have decreased sperm progressive motility, especially older men. An integrative analysis of sperm DFI, sperm progressive motility, age, and infertility conditions can provide a more comprehensive assessment of male fertility.

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.

Sperm DNA Fragmentation: A New Guideline for Clinicians

Sperm DNA integrity is crucial for fertilization and development of healthy offspring. The spermatozoon undergoes extensive molecular remodeling of its nucleus during later phases of spermatogenesis, which imparts compaction and protects the genetic content. Testicular (defective maturation and abortive apoptosis) and post-testicular (oxidative stress) mechanisms are implicated in the etiology of sperm DNA fragmentation (SDF), which affects both natural and assisted reproduction. Several clinical and environmental factors are known to negatively impact sperm DNA integrity. An increasing number of reports emphasizes the direct relationship between sperm DNA damage and male infertility. Currently, several assays are available to assess sperm DNA damage, however, routine assessment of SDF in clinical practice is not recommended by professional organizations. This article provides an overview of SDF types, origin and comparative analysis of various SDF assays while primarily focusing on the clinical indications of SDF testing. Importantly, we report four clinical cases where SDF testing had played a significant role in improving fertility outcome. In light of these clinical case reports and recent scientific evidence, this review provides expert recommendations on SDF testing and examines the advantages and drawbacks of the clinical utility of SDF testing using Strength-Weaknesses-Opportunities-Threats (SWOT) analysis.

Progress in Research on Sperm DNA Fragmentation

With the increasing incidence of male infertility, routine detection of semen is insufficient to accurately assess male fertility. Infertile men, who have lower odds of conceiving naturally, exhibit high levels of sperm DNA fragmentation (SDF). The mechanisms driving SDF include abnormal spermatogenesis, oxidative stress damage, and abnormal sperm apoptosis. As these factors can induce SDF and subsequent radical changes leading to male infertility, detection of the extent of SDF has become an efficient routine method for semen analysis. Although it is still debated, SDF detection has become a research hotspot in the field of reproductive medicine as a more accurate indicator for assessing sperm quality and male fertility. SDF may be involved in male infertility, reproductive assisted outcomes, and growth and development of offspring. The effective detection methods of SDF are sperm chromatin structure analysis (SCSA), terminal transferase-mediated dUTP end labeling (TUNEL) assay, single-cell gel electrophoresis (SCGE) assay, and sperm chromatin dispersion (SCD) test, and all of these methods are valuable for assisted reproductive techniques. Currently, the preferred method for detecting sperm DNA integrity is SCSA. However, the regulation network of SDF is very complex because the sperm DNA differs from the somatic cell DNA with its unique structure. A multitude of molecular factors, including coding genes, non-coding genes, or methylated DNA, participate in the complex physiological regulation activities associated with SDF. Studying SDF occurrence and the underlying mechanisms may effectively improve its clinical treatments. This review aimed to outline the research status of SDF mechanism and detection technology-related issues, as well as the effect of increased SDF rate, aiming to provide a basis for clinical male infertility diagnosis and treatment.

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.