Characterization of subsets of human spermatozoa at different stages of maturation: implications in the diagnosis and treatment of male infertility

Orchestrating the antioxidant defenses in the epididymis

BACKGROUND

During the post-testicular maturation that occurs in the epididymis, spermatozoa need to face biochemical and morphological changes that may make them vulnerable to oxidative damage. During spermatogenesis and the epididymal maturation, the spermatozoon acquires antioxidant enzymes needed to face possible increases of reactive oxygen species (ROS) produced by its own aerobic metabolism but also due to ROS produced in high quantities by abnormal spermatozoa.

OBJECTIVES

Provide an up-to-date review of the enzymatic antioxidant system in the epididymis.

MATERIAL AND METHODS

A thorough literature review was performed for papers concerning the players of the antioxidant defenses in the epididymis.

RESULTS

The antioxidant system in the epididymis is composed by superoxide dismutases, catalase, glutathione peroxidases, peroxiredoxins, glutathione-S-transferases, thioredoxins and thioredoxin reductase. They work together to maintain low levels of ROS during the epididymal maturation. Knockout models revealed that the absence of one of the enzyme impact sperm quality affecting a variety of proteins involved in motility, the ability to fertilize oocyte, and promotes oxidative damage to the sperm DNA.

DISCUSSION AND CONCLUSIONS

These findings suggest that each enzyme is playing a specific role, and in most of the cases, no compensatory mechanisms are put in place when one enzyme is absent. This review highlights the different antioxidant enzymes in the epididymis and their role during maturation of the spermatozoon.

Proteins as the Molecular Markers of Male Fertility

Proteins play a key role in many functions such as metabolic activity, differentiation, as cargos, and cell fate regulators. It is necessary to know about the proteins involved in male fertility to develop remedies for the treatment of male infertility. However, the role of the proteins is not limited to particular aspect in the biological systems. Some of the proteins act as ion channels such as catsper, and protein such as Nanos is a translational repressor in germ cells and expressed in prenatal period whose role in male fertility is not clearly understood. Rbm5 is a pre-mRNA splicing factor necessary for sperm differentiation whose loss results in deficit in sperm production. DEFB114 is a beta-defensin family protein necessary for sperm motility in lipopolysaccharide-challenged mice. TEX101 is a plasma membrane specific germ cell protein whose function is not clearly identified. Gpr56 is an another adhesion protein whose null mutation leads to arrest of production of pupps. Amyloid precursor protein in Alzheimer's disease plays a role in male fertility whose function is uncertain which has to be considered while targeting them. The study on amyloid precursor protein in male fertility is a novel thing, but requires further study in correlation to Alzheimer's disease.

Toxicity of 32.2 kDa MW Escherichia coli Pili Adhesin Isolated from Infertile Male Semen in Reproductive System

Escherichia coli (E. coli) is the leading cause of male genital tract infection with no symptoms of infertility. Protein E. coli pili hemagglutinin isolated from infertile male sperm with 32.2 kDa MW acts as adhesion in spermatozoa. This study aimed to prove whether E. coli pili adhesin 32.2 kDa MW is toxic to male reproductive system. Samples consisted of spermatozoa of 30 guinea pigs divided into three groups: control, immunized with E. coli pili adhesin 32.2 kDa MW protein, and transurethral infected E. coli. Observations of sperm motility, vitality and morphology were performed under a microscope. MDA levels and sperm DNA damage were measured by a spectrophotometer and comet assay method and observed using a fluorescent microscope. There was no difference between control and immunization group of E. coli pili adhesin in motility (p=0.499), vitality (p=0.817) and morphology (p=0.176); between control and transuretral infection groups in motility (p=0.000), vitality (p=0.000) and morphology (p=0.000); and between control and both treatment groups in motility (p=0.001), vitality (p=0,000) and morphology (p=0.000). Histologic analysis showed E. coli pili adhesin of 32.2 kDa MW immunization group did not suffer from testicular tissue damage, while the positive group showed a deterioration of seminiferous tubular cells. MDA levels differed between immunization group E. coli pili, transurethral infection group, and control (p=0.024) and between transurethral and control (p=0.007) groups. However, between control and immunized group with E. coli pili protein showed no difference (p=0.251). DNA damage differed (p=0.000) between immunized group with E. coli pili, transurethral infection and control group; between control and transurethral infected group (p=0.000); and between transurethral infection group and E. coli pili protein immunization group (p=0.000). However, between control and E. coli pili immunization group showed no difference (p=0.600). In conclusion, E. coli pili adhesin 32.2 kDa MW protein is not toxic for sperm quality and the quality of sperm molecules.

Testicular sperm is superior to ejaculated sperm for ICSI in cryptozoospermia: An update systematic review and meta-analysis

Intracytoplasmic sperm injection (ICSI) is well established and provides patients with severely impaired sperm quality with an opportunity to father a child. However, previous studies do not clearly indicate whether male with cryptozoospermia should use testicular sperm or ejaculated sperm for ICSI. The newest systematic review of this topic also gave a controversial conclusion that was based on incorrect pooling result. Moreover, two clinical studies published after the systematic review. In the present update systematic review and meta-analysis, a comprehensive citation search for relevant studies was performed using the Cochrane library databases, Embase, Ovid MEDLINE, PubMed, ScienceDirect, Scopus, and Web of Science up to September 2017. The search returned 313 records, in which six studies were included in quantitative synthesis. These studies involved 578 male infertility patients who had undergone 761 ICSI cycles. The risk ratios favour fresh testicular sperm for good quality embryo rate (1.17, 95% CI 1.05–1.30, P = 0.005), implantation rate (95% CI 1.02–2.26, P = 0.04), and pregnancy rate (RR = 1.74, 95% CI 1.20–2.52, P = 0.004). In conclusion, the existing evidence suggests that testicular sperm is better than ejaculated sperm for ICSI in male with cryptozoospermia.

Lower dietary n-6 : n-3 ratio and high-dose vitamin E supplementation improve sperm morphology and oxidative stress in boars

A 2×2 factorial experiment (10 boars per treatment) was conducted for 16 weeks to evaluate the effects of the dietary n-6:n-3 ratio (14:1 vs 6:1) and vitamin E (200 vs 400mg kg^-1) on boar sperm morphology and oxidative stress. Sperm mitochondrial membrane potential (MMP), reactive oxygen species (ROS), DNA damage (8-hydroxydeoxyguanosine; 8-OHdG), seminal lipoperoxidation (malondialdehyde; MDA) and antioxidant capacity in the serum, spermatozoa and seminal plasma were assessed as indicators of oxidative stress. Sperm production was similar among groups but increased (P<0.05) throughout the 16 weeks of the study. Although sperm α-tocopherol content, ROS and seminal MDA did not differ between the two dietary n-6:n-3 ratio treatments, enhanced antioxidant enzyme activity and MMP, but decreased 8-OHdG, were found in spermatozoa from boars consuming the 6:1 diet. The diet with the 6:1 ratio positively affected sperm morphology at Weeks 12 and 16 (P<0.05). The α-tocopherol content and antioxidant capacity increased in boars with increasing levels of vitamin E supplementation. Compared with low-dose vitamin E, high-dose vitamin E supplementation improved sperm morphology. Overall, the results indicate that an n-6:n-3 ratio of 6:1 and 400 mg/kg vitamin E have beneficial effects on sperm morphology by improving antioxidative stress.

Effect of selenium on testicular damage induced by varicocele in adult male Wistar rats

PROJECT

Varicocele is an abnormal tortuosity and distension of the veins of the pampiniform plexus in the spermatic cord. It is the most common surgically correctable cause of male infertility. Several studies have revealed the effects of increased oxidative stress on serum, semen, and testicular tissues in patients with varicocele or in animal models. The aim of this study was to investigate the effects of sodium selenite on testicular damage induced by experimental left varicocele in male Wistar rats.

PROCEDURE

In the present study, the effects of oral administration of sodium selenite (at doses of 0.05, 0.1, 0.2, and 0.4mg/kg bw) were assessed in normal and varicocelized rats.

RESULTS

The varicocelized control rats showed decrease in sperm quality parameters, decreased activity of testes CAT, GPX and SOD, increased levels of MDA, and damage in testicular architecture. Administration of sodium selenite significantly reduced these changes to nearly normal levels, but did not change these parameters in normal rats. Histopathological studies further confirmed the protective effects of sodium selenite on varicocele-induced testicular damage in rats. Administrations of sodium selenite did not change these parameters in normal rats.

CONCLUSIONS

Taken together, the results of this study suggest that sodium selenite treatment may have beneficial effect on the testes of varicocelized rats.

Effects of pomegranate peel extract on histopathology, testosterone levels and sperm of testicular torsion–detorsion induced in adult Wistar rats

Background

In the present study, effects of pomegranate peel extract have been evaluated on decreasing the damage induced by testis torsion.

Methods

In this study, 30 adult Wistar rats were randomly divided into three groups of control, experimental (1) and experimental (2). Control: no ischemia, received vehicle alone, exposed to sham operation. Experimental (1): Received the vehicle alone during ischemia followed by 60 days’ reperfusion. Experimental (2): After performing ischemia reperfusion, 500 mg/kg of pomegranate peel extract has been used for 60 days. Blood samples and sperm samples were collected. Testes were harvested and stained with haematoxylin and eosin to study the structure of seminiferous tubules.

Results

The statistical comparison between sperm count and their viability and testosterone hormone amount showed a significant difference between control and experimental (1) groups and control and experimental (2) groups. The results showed an improvement of morphological condition of seminiferous tubules.

Conclusions

Pomegranate peel extract has revealed desirable changes on the effective parameters in infertility.

Clinical utility of sperm DNA fragmentation testing: concise practice recommendations

Sperm DNA integrity is generally acknowledged as an essential component for human reproduction. While the negative impact of high sperm DNA fragmentation (SDF) on outcomes of natural pregnancy and assisted reproductive technology (ART) is well known, the clinical indication of SDF testing is less well defined. A recent review on clinical utility of SDF testing highlighted the different SDF assays and clinical indications of SDF testing. This concise practice recommendations aim at summarizing the evidence and presenting to the readers the essence of the clinical utility of SDF testing based on the currently existing evidence. The potential role of SDF testing in varicocelectomy candidates, couples with recurrent pregnancy loss, patients with unexplained infertility, couples with failed assisted reproduction, and infertile men with exposure to modifiable lifestyle risk factors is illustrated. Recommendations from an expert panel on each clinical condition is presented, with levels of evidence.

The Society for Translational Medicine: clinical practice guidelines for sperm DNA fragmentation testing in male infertility

Sperm DNA fragmentation (SDF) testing has been emerging as a valuable tool for male fertility evaluation. While the essential role of sperm DNA integrity in human reproduction was extensively studied, the clinical indication of SDF testing is less clear. This clinical practice guideline provides recommendations of clinical utility of the test supported by evidence. It is intended to serve as a reference for fertility specialists in identifying the circumstances in which SDF testing should be of greatest clinical value. SDF testing is recommended in patients with clinical varicocele and borderline to normal semen parameters as it can better select varicocelectomy candidates. Outcomes of natural pregnancy and assisted reproductive techniques (ART) can be predicted by result of SDF tests. High SDF is also linked with recurrent pregnancy loss (RPL) and failure of ART. Result of SDF testing may change the management decision by selecting the most appropriate ART with the highest success rate for infertile couples. Several studies have demonstrated the benefit in using testicular instead of ejaculated sperm in men with high SDF, oligozoospermia or recurrent in vitro fertilization (IVF) failure. Infertile men with modifiable lifestyle factor may benefit from SDF testing by reinforcing risk factor modification and monitoring patient's progress to intervention.

Proteomic analysis of mature and immature ejaculated spermatozoa from fertile men

Dysfunctional spermatozoa maturation is the main reason for the decrease in sperm motility and morphology in infertile men. Ejaculated spermatozoa from healthy fertile men were separated into four fractions using three-layer density gradient. Proteins were extracted and bands were digested on a LTQ-Orbitrap Elite hybrid mass spectrometer system. Functional annotations of proteins were obtained using bioinformatics tools and pathway databases. Western blotting was performed to verify the expression levels of the proteins of interest. 1469 proteins were identified in four fractions of spermatozoa. The number of detected proteins decreased according to the maturation level of spermatozoa. During spermatozoa maturation, proteins involved in gamete generation, cell motility, energy metabolism and oxidative phosphorylation processes showed increasing expression levels and those involved in protein biosynthesis, protein transport, protein ubiquitination, and response to oxidative stress processes showed decreasing expression levels. We validated four proteins (HSP 70 1A, clusterin, tektin 2 and tektin 3) by Western blotting. The study shows protein markers that may provide insight into the ejaculated spermatozoa proteins in different stages of sperm maturation that may be altered or modified in infertile men.

Clinical utility of sperm DNA fragmentation testing: practice recommendations based on clinical scenarios

Sperm DNA fragmentation (SDF) has been generally acknowledged as a valuable tool for male fertility evaluation. While its detrimental implications on sperm function were extensively investigated, little is known about the actual indications for performing SDF analysis. This review delivers practice based recommendations on commonly encountered scenarios in the clinic. An illustrative description of the different SDF measurement techniques is presented. SDF testing is recommended in patients with clinical varicocele and borderline to normal semen parameters as it can better select varicocelectomy candidates. High SDF is also linked with recurrent spontaneous abortion (RSA) and can influence outcomes of different assisted reproductive techniques. Several studies have shown some benefit in using testicular sperm rather than ejaculated sperm in men with high SDF, oligozoospermia or recurrent in vitro fertilization (IVF) failure. Infertile men with evidence of exposure to pollutants can benefit from sperm DNA testing as it can help reinforce the importance of lifestyle modification (e.g., cessation of cigarette smoking, antioxidant therapy), predict fertility and monitor the patient’s response to intervention.

Evaluation of urinary metal concentrations and sperm DNA damage in infertile men from an infertility clinic

This study aimed to examine associations between urinary metal concentrations and sperm DNA damage. Thirteen metals [arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), molybdenum (Mo), mercury (Hg), nickel (Ni), selenium (Se), and zinc (Zn)] were detected in urine samples of 207 infertile men from an infertility clinic using inductively coupled plasma mass spectrometry, and also, sperm DNA damage (tail length, percent DNA tail, and tail distributed moment) were assessed using neutral comet assay. We found that urinary Hg and Ni were associated with increasing trends for tail length (both p for trend<0.05), and that urinary Mn was associated with increasing trend for tail distributed moment (p for trend=0.02). These associations did persist even when considering multiple metals. Our results suggest that environmental exposure to Hg, Mn, and Ni may be associated with increased sperm DNA damage.

Selective use of percutaneous testis biopsy to optimize IVF-ICSI outcomes: a case series

Background

Sperm quality may degrade during transit through the male reproductive tract in some individuals. In this setting surgically retrieved testicular sperm may outperform ejaculated samples for use with in vitro fertilization (IVF) and intracytoplasmic sperm injection (IVF-ICSI). We sought to describe one center’s experience with the use of fresh testicular sperm after prior failed IVF-ICSI with ejaculated samples.

Results

A retrospective review was conducted evaluating IVF-ICSI cycles performed at a tertiary IVF unit between 2009 and 2014. Couples who were managed with percutaneous testis biopsy to obtain sperm, despite availability of ejaculated sperm, were included. Four couples who underwent a total of 6 percutaneous testis biopsy/IVF-ICSI cycles were identified. Collectively, the couples had undergone 9 prior IVF-ICSI cycles using fresh ejaculated sperm without successful pregnancy. From the six cycles that used fresh testicular sperm four live births resulted (1 twin gestation, 3 singletons). Only 1 of the 4 couples remained childless.

Conclusions

For patients who have had prior failed IVF-ICSI attempts, this small case series demonstrates a possible therapeutic benefit when freshly procured testicular sperm are used in lieu of ejaculated samples.

Melatonin and alpha lipoic acid attenuate lopinavir/ritonavir - induced testicular toxicity in albino rats

The use of lopinavir/ritonavir (LPV/r) could be associated with testicular toxicity as a limiting factor. The present study evaluated the effects of melatonin (MT) and alpha lipoic (ALA) acid on LPV/r–induced testicular toxicity in male albino rats. Eighty five male albino rats used for this study were randomized into 6 groups (A-F). Rats in groups A1 and A2 served as placebo and solvent control and were orally exposed to water and 1% ethanol, respectively. Rats in group B were exposed to oral doses of MT (10 mg kg-1/day), ALA (10 mg kg-1/day) and combined doses of MT and ALA, respectively. Rats in group C were exposed to oral doses of LPV/r (22.9/5.71 - 91.4/22.9 mg kg-1/ day), respectively. Rats in group D-F were exposed to oral doses of MT (10 mg kg-1/day), ALA (10 mg kg-1/day) and combined doses of MT and ALA prior to oral exposure to LPV/r (22.9/5.71 - 91.4/22.9 mg kg-1/day), respectively. At the end of 60 days of exposure to drugs, rats were sacrificed; blood was collected and serum extracted and evaluated for testosterone. Testes were collected and evaluated for sperm parameters. LPV/r-treated rats showed significant (P<0.05) and dose-dependent decreases in sperm count, sperm motility, sperm viability and serum testosterone levels with increases in abnormal sperm cells, debris, and primordial sperm cells when compared to placebo control. However, LPV/r-induced changes in sperm parameters and serum testosterone levels were attenuated in rats pretreated with MT and ALA. The best effects were observed in rats pretreated with combined doses of MT and ALA. Melatonin and alpha lipoic acid have potential to reduce testicular toxicity associated with lopinavir/ritonavir treatment.

Protection against Cyclosporine-Induced Reprotoxicity by Satureja khuzestanica Essential Oil in Male Rats

Background

The effects of cyclosporine (Cs), a fungal cyclic polypeptide with potent immunosuppressive activity, on fertility have assumed greater significance with the increasing numbers of transplantations being performed all over the world. Current study was undertaken to investigate the potential of Satureja khuzestanica Essential Oil (SEO) as an antioxidant to mitigate Cs-induced reprotoxicity.

Materials and Methods

In this experimental study (April-July 2012), thirty-two adult male Wistar rats were randomly divided into 4 groups of 8 animals each. Two groups of rats were administered Cs [40 mg/kg/day, per oral (p.o.)] for 45 days. One of these groups received SEO (225 mg/kg/day, p.o.) four hours after Cs administration. A vehicle-treated control group and a SEO control group were also included. Epididymal sperm characteristics, in vitro fertilizing capacity as well as embryo development were evaluated. For statistical analysis, one-way ANOVA and Tukey’s post-hoc test were used, and the value of P<0.05 was considered as the criterion for statistical significance.

Results

Sperm count and viability along with fertilization and blastocyst development rates were significantly decreased by Cs treatment. Moreover, Cs-treated group showed significant increases in DNA damage, protamine deficiency of the sperm cells and proportion of spermatozoa with cytoplasmic droplet. Notably, aforementioned parameters were improved to near normal level by SEO co-administration.

Conclusion

These results suggest that SEO has a protective action against Cs-induced reprotoxicity in a rat model.

Protective Effect of Royal Jelly on In Vitro Fertilization (IVF) in Male Mice Treated with Oxymetholone

Objective

This study aimed to investigate the effects of royal jelly (RJ) on catalase, total antioxidant capacity and embryo development in adult mice treated with oxymetholone (OXM).

Materials and Methods

In this exprimental study, 32 male and 96 female adult Naval Medical Research Institute (NMRI) mice (7-9 weeks of age) with a ratio of 1:3 for fertili- zation purposes were randomly divided into 4 groups as follows: i. Control group (n=8) receiving 0.1 ml/mice saline daily by gavage for 30 day, ii. RJ group (n=8) treated with RJ at a dose of 100 mg/kg daily by gavage for 30 days, iii. OXM group (n=8) receiving OXM at the dose of 5 mg/kg daily by gavage for 30 days and iv. RJ+OXM group (n=8) receiving RJ at the dose of 100 mg/kg daily by gavage concomitant with 100 mg/kg OXM adminis- tration for 30 days.

Results

Analysis revealed a significant reduction in catalase, total antioxidant, as well as embryo development in OXM group (P<0.05). However, RJ group showed a salient recovery in the all of the above mentioned parameters and embryo toxicity.

Conclusion

The results of this study indicated a partially protective effect of RJ against OXM-induced embryo toxicity.

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

OBJECTIVE

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

DESIGN

Prospective, observational, cohort study.

SETTING

Private IVF centers.

PATIENT(S)

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

INTERVENTION(S)

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

MAIN OUTCOME MEASURE(S)

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

RESULT(S)

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

CONCLUSION(S)

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

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.

Successful Pregnancy in a Couple with Severe Male Factor Infertility after Selection of Sperm with Cytoplasmic Droplets

We present live births resulting from two separate IVF cycles in a couple in which ICSI was performed with sperm specifically selected for presence of small cytoplasmic droplets. These cycles followed previous cycles using standard sperm selection methods in which very poor embryo development and no pregnancies ensued. The male partner was diagnosed with severe male factor infertility including elevated DNA fragmentation.

Investigation of the stallion sperm proteome by mass spectrometry

Stallion spermatozoa continue to present scientific and clinical challenges with regard to the biological mechanisms responsible for their survival and function. In particular, deeper understanding of sperm energy metabolism, defence against oxidative damage and cell–cell interactions should improve fertility assessment and the application of advanced reproductive technologies in the equine species. In this study, we used highly sensitive LC–MS/MS technology and sequence database analysis to identify and characterise the proteome of Percoll-isolated ejaculated equine spermatozoa, with the aim of furthering our understanding of this cell's complex biological machinery. We were able to identify 9883 peptides comprising 1030 proteins, which were subsequently attributed to 975 gene products. Gene ontology analysis for molecular and cellular processes revealed new information about the metabolism, antioxidant defences and receptors of stallion spermatozoa. Mitochondrial proteins and those involved in catabolic processes constituted dominant categories. Several enzymes specific to β-oxidation of fatty acids were identified, and further experiments were carried out to ascertain their functional significance. Inhibition of carnitine palmitoyl transferase 1, a rate-limiting enzyme of β-oxidation, reduced motility parameters, indicating that β-oxidation contributes to maintenance of motility in stallion spermatozoa.

Correlation between sperm parameters and protein expression of antioxidative defense enzymes in seminal plasma: a pilot study

BACKGROUND

Semen analysis is the cornerstone in the evaluation of male (in)fertility. However, there are men with normal semen tests but with impaired fertilizing ability, as well as fertile men with poor sperm characteristics. Thus, there is rising interest to find novel parameters that will help to predict and define the functional capacity of spermatozoa.

METHODS

We examined whether there is a correlation between semen parameters (count, progressive motility, and morphology) and protein expression/activity of antioxidative defense enzymes in seminal plasma from 10 normospermic subjects.

RESULTS

Sperm progressive motility was in positive correlation with seminal plasma protein expression of both superoxide dismutase (SOD) isoforms (MnSOD and CuZnSOD) and catalase. Also, positive correlation was observed between sperm count and MnSOD protein expression, as well as between sperm morphology and protein expression of catalase in seminal plasma. In contrast, protein expression of glutathione peroxidase was not in correlation with any sperm parameter, while its activity negatively correlated with sperm morphology and motility.

CONCLUSIONS

These data suggest that evaluation of protein expression of antioxidative defense enzymes in seminal plasma might be of importance in the evaluation of male fertility status and that could be used as an additional biomarker along with classic semen analysis in assessment of semen quality.

Testicular sperm aspiration for nonazoospermic men: sperm retrieval and intracytoplasmic sperm injection outcomes

OBJECTIVE

To evaluate testicular sperm aspiration (TESA) sperm retrieval rates and intracytoplasmic sperm injection outcomes in nonazoospermic men.

MATERIALS AND METHODS

Data were collected retrospectively from 54 consecutive, nonazoospermic, infertile men who underwent TESA between March 2007 and September 2012. Sperm retrieval rates and clinical pregnancy outcomes were recorded. Patients were subgrouped based on clinical diagnosis: group 1, anejaculation (primary, situational); group 2, idiopathic severe oligoasthenozoospermia; and group 3, severe oligoasthenozoospermia after vasovasostomy.

RESULTS

Mean (± standard deviation) paternal and maternal ages were 39 ± 7 and 35 ± 5 years, respectively. Using TESA, sperm recovery was successful in 94% (51 of 54) of the men overall and in 100% (17 of 17) of the men in group 1, 90% (28 of 31) in group 2, and 100% (6 of 6) in group 3. Overall, 35% of the couples achieved a clinical pregnancy using TESA sperm (with a mean of 1.7 ± 0.9 embryos transferred per cycle). The clinical pregnancy rates were 40% in group 1, 33% in group 2, and 33% in group 3 with no significant difference in paternal or maternal age between groups.

CONCLUSION

The data indicate that TESA yields high sperm retrieval rates in select groups of nonazoospermic infertile men, and this approach results in acceptable pregnancy rates regardless of the male infertility etiology. Randomized controlled trials comparing ejaculated vs testicular sperm are needed to assess the true benefit of TESA-intracytoplasmic sperm injection in these couples.

Effect of cryopreservation on the sperm DNA fragmentation dynamics of the bottlenose dolphin (Tursiops truncatus)

Sperm DNA fragmentation is one of the major causes of infertility; the sperm chromatin dispersion test (SCDt) evaluates this parameter and offers the advantage of species-specific validated protocol and ease of use under field conditions. The main purpose of this study was to evaluate sperm DNA fragmentation dynamics in both fresh and post-thaw bottlenose dolphin sperm using the SCDt following different cryopreservation protocols to gain new information about the post-thaw differential sperm DNA longevity in this species. Fresh and cryopreserved semen samples from five bottlenose dolphins were examined for sperm DNA fragmentation dynamics using the SCDt (Halomax(®)). Sperm DNA fragmentation was assessed immediately at collection and following cryopreservation (T0) and then after 0.5, 1, 4, 8, 24, 48 and 72 h incubation at 37°C. Serially collected ejaculates from four dolphins were frozen using different cryopreservation protocols in a TES-TRIS-fructose buffer (TTF), an egg-yolk-free vegetable lipid LP1 buffer (LP1) and human sperm preservation medium (HSPM). Fresh ejaculated spermatozoa initially showed low levels of DNA fragmentation for up to 48 h. Lower Sperm DNA fragmentation (SDF) was found in the second fresh ejaculate compared to the first when more than one sample was collected on the same day (p < 0.05); this difference was not apparent in any other seminal characteristic. While there was no difference observed in SDF between fresh and frozen-thawed sperm using the different cryopreservation protocols immediately after thawing (T0), frozen-thawed spermatozoa incubated at 37°C showed an increase in the rate of SDF after 24 h. Sperm frozen in the LP1(℗) buffer had higher levels (p < 0.05) of DNA fragmentation after 24- and 48-h incubation than those frozen in TTF or HSPM. No correlation was found between any seminal characteristic and DNA fragmentation in either fresh and/or frozen-thawed samples.

Seminal quality in the first fraction of ejaculate

Semen samples from 40 patients were collected in consecutive fractions. The variability in semen quality of each fraction was then determined. The first ejaculated fraction (FEF) primarily contained prostatic secretions, while the second ejaculate fraction (SEF) held the majority of the spermatozoa suspended in the secretions from the seminal vesicle. Differences in sperm quality were observed when the FEF was compared to the SEF and the total ejaculate fraction (TEF). These included the seminal parameters (volume, sperm concentration, motility) and sperm DNA fragmentation (SDF). When compared to TEF and SEF, the FEF presented a lower volume, higher sperm concentration, higher motility rates, and lower SDF. The data suggest that the first fraction renders an improved subpopulation of spermatozoa, with lower SDF. Spermatozoa from this fraction and hence their use for ART may have a positive effect on fertilization and embryo development.

Human sperm sex chromosome disomy and sperm DNA damage assessed by the neutral comet assay

STUDY QUESTION

Is there an association between human sperm sex chromosome disomy and sperm DNA damage?

SUMMARY ANSWER

An increase in human sperm XY disomy was associated with higher comet extent; however, there was no other consistent association of sex chromosome disomies with DNA damage.

WHAT IS KNOWN ALREADY

There is limited published research on the association between sex chromosome disomy and sperm DNA damage and the findings are not consistent across studies.

STUDY DESIGN, SIZE, AND DURATION

We conducted a cross-sectional study of 190 men (25% ever smoker, 75% never smoker) from subfertile couples presenting at the Massachusetts General Hospital Fertility Clinic from January 2000 to May 2003.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Multiprobe fluorescence in situ hybridization for chromosomes X, Y and 18 was used to determine XX, YY, XY and total sex chromosome disomy in sperm nuclei using an automated scoring method. The neutral comet assay was used to measure sperm DNA damage, as reflected by comet extent, percentage DNA in the comet tail, and tail distributed moment. Univariate and multiple linear regression models were constructed with sex chromosome disomy (separate models for each of the four disomic conditions) as the independent variable, and DNA damage parameters (separate models for each measure of DNA damage) as the dependent variable.

MAIN RESULTS AND THE ROLE OF CHANCE

Men with current or past smoking history had significantly greater comet extent (µm: regression coefficients with 95% CI) [XX18: 15.17 (1.98, 28.36); YY18: 14.68 (1.50, 27.86); XY18: 15.41 (2.37, 28.45); Total Sex Chromosome Disomy: 15.23 (2.09, 28.38)], and tail distributed moment [XX18: 3.01 (0.30, 5.72); YY18: 2.95 (0.24, 5.67); XY18: 3.04 (0.36, 5.72); Total Sex Chromosome Disomy: 3.10 (0.31, 5.71)] than men who had never smoked. In regression models adjusted for age and smoking, there was a positive association between XY disomy and comet extent. For an increase in XY disomy from 0.56 to 1.47% (representing the 25th to 75th percentile), there was a mean increase of 5.08 µm in comet extent. No other statistically significant findings were observed.

LIMITATIONS, REASONS FOR CAUTION

A potential limitation of this study is that it is cross-sectional. Cross-sectional analyses by nature do not lend themselves to inference about directionality for any observed associations; therefore we cannot determine which variable is the cause and which one is the effect. A small sample size may be a further limitation. Comparison of these findings to other studies is limited due to methodological differences.

WIDER IMPLICATIONS OF THE FINDINGS

Although consistent associations across sex chromosome disomies or DNA damage measures were not observed, this study highlights the need to explore etiologies of sperm DNA damage and sex chromosome disomy to better understand the potential mechanistic overlaps between the two.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by NIOSH Grant T42 OH008416, and NIH/NIEHS Grants ES 009718, ES 000002, and R01 ES017457. During the study M.E.M. was affiliated with the Department of Environmental Health at the Harvard School of Public Health.

TRIAL REGISTRATION NUMBER

N/A.

Characterizing semen parameters and their association with reactive oxygen species in infertile men

BACKGROUND

A routine semen analysis is a first step in the laboratory evaluation of the infertile male. In addition, other tests such as measurement of reactive oxygen species can provide additional information regarding the etiology of male infertility. The objective of this study was to investigate the association of semen parameters with reactive oxygen species (ROS) in two groups: healthy donors of unproven and proven fertility and infertile men. In addition, we sought to establish an ROS cutoff value in seminal plasma at which a patient may be predicted to be infertile.

METHODS

Seminal ejaculates from 318 infertile patients and 56 donors, including those with proven fertility were examined for semen parameters and ROS levels. Correlations were determined between traditional semen parameters and levels of ROS among the study participants. ROS levels were measured using chemiluminescence assay. Receiver operating characteristic curves were obtained to calculate a cutoff value for these tests.

RESULTS

Proven Donors (n = 28) and Proven Donors within the past 2 years (n = 16) showed significantly better semen parameters than All Patients group (n = 318). Significantly lower ROS levels were seen in the two Proven Donor groups compared with All Patients. The cutoff value of ROS in Proven Donors was determined to be 91.9 RLU/s with a specificity of 68.8% and a sensitivity of 93.8%.

CONCLUSIONS

Infertile men, irrespective of their clinical diagnoses, have reduced semen parameters and elevated ROS levels compared to proven fertile men who have established a pregnancy recently or in the past. Reactive oxygen species are negatively correlated with traditional semen parameters such as concentration, motility and morphology. Measuring ROS levels in the seminal ejaculates provides clinically-relevant information to clinicians.

Varicocele decreases epididymal neutral α-glucosidase and is associated with alteration of nuclear DNA and plasma membrane in spermatozoa

OBJECTIVE

To assess the relationship between a marker of epididymal function and both the fragmentation of the sperm nucleus and the integrity and maturity of the sperm membrane in patients with or without varicocele.

PATIENTS AND METHODS

Semen samples were obtained from men with varicocele grades II and III (n = 60) and from a control group with zoospermia defined as normal (n = 30). Samples were evaluated by a spermiogram, a hypoosmotic swelling test (HOST), neutral α-glucosidase (NAG) enzyme activity, sperm hyaluronan-binding assay (HBA) and DNA fragmentation using a sperm chromatin dispersion (SCD) test.

RESULTS

Seminal plasma NAG levels, percentage of sperm bound to hyaluronic acid, HOST-positive cells and sperm quality were significantly lower in the varicocele compared with the control group. Higher levels of sperm DNA fragmentation, as measured by SCD, were also observed in the varicocele group compared with the control group. Seminal NAG activity levels showed a strong negative correlation with DNA fragmentation and a significant positive correlation with the HBA test and the HOST.

CONCLUSIONS

Varicocele causes a reduction in NAG activity by the epididymis that is associated with damage to both the membrane and sperm nucleus and a reduction in the seminal parameters. NAG levels were correlated with the quality of the sperm membrane and nucleus. Data suggest that a reduction of fertilization capacity in men during varicocele can result from damage to both the testis and the epididymis.

Induction of sperm impairments in mice as a sensitive biomarker of arsenic toxicity

The ubiquitous presence of arsenic (a toxic metalloid) in our environment, particularly in our drinking water, is a serious health hazard of global concern. The present work deals with the assessment of arsenic toxicity through the analysis of induced sperm impairments in sperm head morphology and sperm count in mice at low exposures compared to the magnitude of response at high exposure levels. The animals were exposed to four doses of arsenic, ranging from lowest dose of 0.3 μg kg(-1) day(-1) (the human reference dose) to higher dose of 30 μg kg(-1) day(-1) for 15 consecutive days. The epididymal sperms were harvested after one spermatogenic cycle on the 36th day and were scored for the presence of any abnormality in their head morphology as well as changes in their count. Exposure to arsenic significantly induced, in a dose-dependent manner, increases in the frequency of sperms with abnormal head morphology from 5.12 % in control to 9.23 % in lowest dose group and 23.02 % in highest dose group. In contrast, the mean sperm counts in the epididymal wash were decreased from 6.05 million per milliliter in the control to 4.95 million per milliliter in the lowest dose group and 3.07 million in the highest dose group. The analysis of sperm impairments in mice was, therefore, found to be a highly sensitive assay to assess arsenic toxicity, exhibiting a marked male reprotoxic effect of arsenic even at its low exposure levels including the human reference dose.

The effect of the in vitro supplementation of exogenous long-chain fatty acids on bovine sperm cell function

This study aimed to investigate the effects of long-chain fatty acids (α-linolenic acid (ALA), docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), linoleic acid (LA), oleic acid (OA) and palmitic acid (PA)) at concentrations of 10-100 µM, on extended bull spermatozoa stored in vitro for up to 7 days. Progressive linear motion (PLM), viability (Experiments 1-3), ability to penetrate artificial mucus (Experiment 1), reactive oxygen species (ROS; Experiment 2) and superoxide production (Experiment 3) were assessed. Spermatozoa maintained the ability to penetrate artificial mucus up to Day 4, irrespective of treatment. In Experiments 2 and 3, DHA and EPA had detrimental effects on PLM and viability. PA preserved PLM and viability at levels greater than the control (P<0.05), whilst keeping ROS levels to a minimum, particularly on Days 1 and 3 (P<0.01) when ROS generation peaked in other treatments. In contrast, superoxide production peaked on Day 0 (Experiment 3) and declined thereafter with no significant effect of fatty acid. This study supports the notion that superoxide dominates on Day 0, whereas its breakdown products, hydrogen peroxide and the hydroxyl radical as assessed by CM-H2DCFDA, contribute to ROS generation on subsequent days.

Assessment of the reproductive toxicity of inhalation exposure to ethyl tertiary butyl ether in male mice with normal, low active and inactive ALDH2

No data are available regarding aldehyde dehydrogenase 2 (ALDH2) polymorphisms related to the reproductive toxicity possibly caused by ethyl tertiary butyl ether (ETBE). In this study, two inhalation experiments were performed in Aldh2 knockout (KO), heterogeneous (HT) and wild type (WT) C57BL/6 male mice exposed to ETBE, and the data about general toxicity, testicular histopathology, sperm head numbers, sperm motility and sperm DNA damage were collected. The results showed that the 13-week exposure to 0, 500, 1,750 and 5,000 ppm ETBE significantly decreased sperm motility and increased levels of sperm DNA strand breaks and 8-hydroxy-deoxyguanosine in both WT and KO mice, the effects were found in 1,750 and 5,000 ppm groups of WT mice, and all of the three exposed groups of KO mice compared to the corresponding control; furthermore, ETBE also caused decrease in the relative weights of testes and epididymides, the slight atrophy of seminiferous tubules of testis and reduction in sperm numbers of KO mice exposed to ≥500 ppm. In the experiment of exposure to lower concentrations of ETBE (0, 50, 200 and 500 ppm) for 9 weeks, the remarkable effects of ETBE on sperm head numbers, sperm motility and sperm DNA damage were further observed in KO and HT mice exposed to 200 ppm ETBE, but not in WT mice. Our findings suggested that only exposure to high concentrations of ETBE might result in reproductive toxicity in mice with normal active ALDH2, while low active and inactive ALDH2 enzyme significantly enhanced the ETBE-induced reproductive toxicity in mice, even exposed to low concentrations of ETBE, mainly due to the accumulation of acetaldehyde as a primary metabolite of ETBE.

Iatrogenic genetic damage of spermatozoa

Various factors that negatively influence male fertility can affect sperm morphology and physiology. Many studies on humans and animals suggest that both radiation and chemotherapy alter the sperm chromatin, inducing significant damage to sperm DNA, and decrease the level of protamination, thereby altering DNA compaction. Spermatozoa from cancer survivors are affected by chemotherapy even years after the end of treatment. We are exposed to various toxicants present in the environment (e.g., products of air pollution, pesticides, and plasticizers) whose impact on human male reproduction has not yet been established.This chapter aims to update our knowledge on how the sperm chromatin structure is modified by external agents and to describe the different strategies available to better study this complex structure in infertile men.