Effects of antioxidants on human sperm preparation techniques

Human Pluripotent Stem Cell-Mesenchymal Stem Cell-Derived Exosomes Promote Ovarian Granulosa Cell Proliferation and Attenuate Cell Apoptosis Induced by Cyclophosphamide in a POI-like Mouse Model

Premature ovarian insufficiency (POI) is a complex disease which causes amenorrhea, hypergonadotropism and infertility in patients no more than 40 years old. Recently, several studies have reported that exosomes have the potential to protect ovarian function using a POI-like mouse model induced by chemotherapy drugs. In this study, the therapeutic potential of exosomes derived from human pluripotent stem cell-mesenchymal stem cells (hiMSC exosomes) was evaluated through a cyclophosphamide (CTX)-induced POI-like mouse model. POI-like pathological changes in mice were determined by serum sex-hormones levels and the available number of ovarian follicles. The expression levels of cellular proliferation proteins and apoptosis-related proteins in mouse ovarian granulosa cells were measured using immunofluorescence, immunohistochemistry and Western blotting. Notably, a positive effect on the preservation of ovarian function was evidenced, since the loss of follicles in the POI-like mouse ovaries was slowed. Additionally, hiMSC exosomes not only restored the levels of serum sex hormones, but also significantly promoted the proliferation of granulosa cells and inhibited cell apoptosis. The current study suggests that the administration of hiMSC exosomes in the ovaries can preserve female-mouse fertility.

Molecular Markers: A New Paradigm in the Prediction of Sperm Freezability

For decades now, sperm cryopreservation has been a pillar of assisted reproduction in animals as well as humans. Nevertheless, the success of cryopreservation varies across species, seasons, and latitudes and even within the same individual. With the dawn of progressive analytical techniques in the field of genomics, proteomics, and metabolomics, new options for a more accurate semen quality assessment have become available. This review summarizes currently available information on specific molecular characteristics of spermatozoa that could predict their cryotolerance before the freezing process. Understanding the changes in sperm biology as a result of their exposure to low temperatures may contribute to the development and implementation of appropriate measures to assure high post-thaw sperm quality. Furthermore, an early prediction of cryotolerance or cryosensitivity may lead to the establishment of customized protocols interconnecting adequate sperm processing procedures, freezing techniques, and cryosupplements that are most feasible for the individual needs of the ejaculate.

The effect of Caulerpa sertularioides extract on bull sperm freezablity and subsequent embryo development

Artificial insemination is a valuable and essential tool in genetic improvement programs, and its success requires proper semen collection, freezing, and thawing procedures. Nowadays, despite applying of advanced protocols for semen cryopreservation, post-thawing sperm quantitative and qualitative parameters are not satisfactorily comparable to fresh sperm. The present study was designed to evaluate the effects of the supplementation of an alcoholic extract of Caulerpa sertolarioides alga into the tris-egg yolk-based Simmental bull sperm freezing media. The pooled semen samples were divided into five groups, of which four were supplemented with 500, 1000, 1500, and 2000 ppm alga extract and one allocated as a control. Total motility, progressive motility, plasma membrane integrity, DNA integrity, apoptosis, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, and total antioxidant capacity (TAC) of sperm were measured. The frozen sperm from each group were used for IVF on the slaughterhouse-derived oocytes. Fertilization, cleavage, and blastocyst rates were assessed for all groups. Total motility, progressive motility, and velocity curvilinear (VCL) parameters were higher (p ≤ 0.05) in group 1000 ppm than the control group. Velocity in a straight path (VSL) was higher (p ≤ 0.05) in all treatment groups except in 500 ppm compared to the control group. Average path velocity (VAP) was higher (p ≤ 0.05) in 1000 and 1500 ppm groups than in the control group. Straightness (STR) showed a higher value (p ≤ 0.05) in 1000 and 2000 ppm than the control group. Groups 500 and 1000 ppm showed more viable sperm than the control group (p ≤ 0.05). DNA damage was lower (p ≤ 0.05) in group 1000 ppm than in the control group. HOST was higher (p ≤ 0.05) in all groups than in the control group. SOD, GPx, and TAC were higher (p ≤ 0.05) in 1000 ppm than the control and all other groups. Apoptosis was not significantly different among the treatment and control groups. In conclusion, supplementation of alcoholic extract of Caulerpa sertularioides into the Simmental bull freezing extender ameliorated the sperm parameters after the freeze-thawing process. Moreover, the results of this study indicated that the best dose to achieve the antioxidant properties of the alga extract in Simmental bull sperm freezing media was 1000 ppm. It was also evident that 1000 ppm alga extract supplementation into the bull sperm improved fertilization, cleavage, and blastocyst rates.

Effect of Microfluidic Sperm Separation vs. Standard Sperm Washing Processes on Laboratory Outcomes and Clinical Pregnancy Rates in an Unselected Patient Population

A prospective, multicenter, randomized, sibling oocyte study was conducted with 86 couples to evaluate if a microfluidic sperm separation device improved ICSI sperm selection and subsequent cycle outcomes of fertilization, blastocyst utilization, ploidy, and clinical pregnancy rate when applied to a general patient population. Patients with at least 10 metaphase II oocytes were enrolled in the study and sibling oocyte groups were split in half. One half of the oocytes underwent ICSI with the control processed sperm and the other half were injected with sperm sorted by the ZyMōt microfluidic sperm separation device. Fertilization rate was recorded and resulting blastocysts were biopsied and evaluated for ploidy status with NGS. Euploid, non-mosaic embryos were randomly selected for single embryo transfer. A total of 787 oocytes were evaluated in the ZyMōt group and 777 in the control group. No statistical differences were observed between ZyMōt and control processing methods in any of the study outcomes evaluated. It is possible that the selection of normal, progressive sperm for ICSI, and the repair capacity of oocytes are sufficient to promote normal embryonic development in the general infertility population.

NADPH Oxidase 5 and Melatonin: Involvement in Ram Sperm Capacitation

Reactive oxygen species (ROS) play an essential role in mammalian sperm capacitation. NADPH oxidase 5 (NOX5) has been described as the main source of ROS production in some mammalian spermatozoa, such as human and equine. On the other hand, melatonin can decrease cellular ROS levels and regulates NOX activity in somatic cells. Therefore, the objectives of this work were (1) to identify NOX5 in ram spermatozoa and analyze its possible changes during in vitro capacitation and (2) to investigate the effect of melatonin on NOX5 expression and localization and on superoxide levels in capacitated ram spermatozoa. Protein bands associated with NOX5 were detected by Western blot analysis. Likewise, indirect immunofluorescence (IIF) revealed six different immunotypes for NOX5, which varied throughout in vitro capacitation. Superoxide (O₂^⋅–), evaluated by DHE/Yo-Pro-1, rose after in vitro capacitation and in the presence of the calcium ionophore A23187 but decreased in the presence of the NOX inhibitor GKT136901. GKT also reduced the percentage of capacitated and acrosome-reacted spermatozoa that had increased during incubation in capacitating conditions. The presence of melatonin at micromolar concentrations avoided the increment in O₂^⋅– and the changes in NOX5 immunotypes provoked by capacitation. In conclusion, NOX5 is present in ram spermatozoa and the changes in its distribution, associated with sperm capacitation, can be prevented by melatonin. To this extent, it could imply that melatonin exerts its antioxidant role, at least in part, by modulating NOX5 activity during ram sperm capacitation.

Sperm Antioxidant Biomarkers and Their Correlation with Clinical Condition and Lifestyle with Regard to Male Reproductive Potential

Measurement of sperm oxidative-antioxidant indicators is widely used in the assessment and detection of biochemical causes of male infertility The main purpose of this study was to identify biomarkers that assist in diagnostics and monitoring of male reproductive potential. We performed the assessment of oxidative-antioxidant malondialdehyde (MDA), glutathione (GSH), and total redox antioxidant potential (TRAP) indicators in seminal plasma, seminogram, clinical condition, and lifestyle of people with reproductive problems. The combined assessment of GSH and TRAP as potential biomarkers of male infertility in semen plasma was characterized by the highest total sensitivity and specificity. Furthermore, we provide evidence that male reproductive potential is significantly correlated with basic sperm parameters, sperm cell membrane integrity, their morphology, lifestyle, eating habits, occupation, and mental health. Our results provide evidence on the importance of oxidative stress and defense against free radicals in diagnosing and monitoring men with infertility that are consistent with previously conducted research. We provide an alternative approach on the possibility of interpreting the combination of the biomarkers that can bring benefits to a multi-threaded approach to the diagnosis and treatment of male infertility.

Carnosine treatment during human semen processing by discontinuous density gradient

The aim of this article was to evaluate the effects of different concentrations of carnosine added during human semen processing. Semen samples from 34 patients were submitted to processing by discontinuous density gradient centrifugation without (control) or with different concentrations of carnosine supplementation as follows: (a) 20 mM of carnosine supplementation on the layers of Percoll; and (b) 50 mM carnosine supplementation. Sperm samples were then washed with human tubal fluid medium and evaluated according to sperm kinetics and functional assessment. For statistical analysis, data were evaluated by a general linear model or a Friedman test, whenever appropriate. The 50 mM carnosine supplementation led to improved sperm mitochondrial activity when compared to untreated samples. Motility variables, such as percentage of motile and progressively motile spermatozoa, average path velocity, straight line velocity, curvilinear velocity and linearity, showed an improvement after semen processing irrespective of carnosine supplementation. Both concentrations of carnosine increased the beat-cross frequency (BCF) when compared to samples before processing. We conclude that carnosine supplementation in semen samples benefits sperm mitochondrial activity and BCF.

Antioxidant therapy in idiopathic oligoasthenoteratozoospermia

Introduction:

Idiopathic oligoasthenoteratozoospermia (iOAT) is commonly encountered during the evaluation of men with infertility. Antioxidants have been utilized empirically in the treatment of iOAT based on their ability to reverse oxidative stress (OS)-induced sperm dysfunction often encountered in this patient population.

Methods:

A literature search was performed using MEDLINE/PubMed, focusing on publications of antioxidant therapies for iOAT. The main objective of our review article was to report the rationale and available evidence supporting the use of antioxidants.

Results:

Antioxidants such as glutathione, vitamins E and C, carnitines, coenzyme-Q10, N-acetylcysteine, selenium, zinc, folic acid, and lycopene have been shown to reduce OS-induced sperm damage. While rigorous scientific evidence in the form of double-blind, placebo-controlled clinical trials is limited, recent systematic reviews and meta-analyses have reported a beneficial effect of antioxidants on semen parameters and live birth rates.

Conclusion:

Additional randomized controlled studies are required to confirm the efficacy and safety of antioxidant supplementation in the medical treatment of idiopathic male infertility as well as the dosage required to improve semen parameters, fertilization rates, and pregnancy outcomes in iOAT.

Comparison of two sperm processing techniques for low complexity assisted fertilization: sperm washing followed by swim-up and discontinuous density gradient centrifugation

Objective

This study aimed to assess and compare sperm motility, concentration, and morphology recovery rates, before and after processing through sperm washing followed by swim-up or discontinuous density gradient centrifugation in normospermic individuals.

Methods

Fifty-eight semen samples were used in double intrauterine insemination procedures; 17 samples (group 1) were prepared with sperm washing followed by swim-up, and 41 (group 2) by discontinuous density gradient centrifugation. This prospective non-randomized study assessed seminal parameters before and after semen processing. A dependent t-test was used for the same technique to analyze seminal parameters before and after semen processing; an independent t-test was used to compare the results before and after processing for both techniques.

Results

The two techniques produced decreases in sample concentration (sperm washing followed by swim-up: P<0.000006; discontinuous density gradient centrifugation: P=0.008457) and increases in motility and normal morphology sperm rates after processing. The difference in sperm motility between the two techniques was not statistically significant. Sperm washing followed by swim-up had better morphology recovery rates than discontinuous density gradient centrifugation (P=0.0095); and the density gradient group had better concentration recovery rates than the swim-up group (P=0.0027).

Conclusion

The two methods successfully recovered the minimum sperm values needed to perform intrauterine insemination. Sperm washing followed by swim-up is indicated for semen with high sperm concentration and better morphology recovery rates. Discontinuous density gradient centrifugation produced improved concentration recovery rates.

Preventive effect of Desferal on sperm motility and morphology

Transition metal ions, mainly iron, are involved in the generation of highly reactive hydroxyl radicals, which are the most powerful inducers of oxidative damage to all biomolecules. The lipids in sperm membranes are highly susceptible to oxidation. Sperm lipid peroxidation (LPO) leads to decrease of motility and reduction of likelihood for sperm-oocyte fusion. The excess radical production may affect also the spermatozoa morphology. The aim of the present study was to investigate the effect of Desferal on the LPO, motility, and morphology of boar sperm subjected to oxidative stress. After collection, the ejaculates were equally separated and diluted in a commercial semen extender (experiment 1) or in physiological saline (experiment 2). The ejaculates of the 2 experiments were divided into aliquots, which were incubated with one of the following agents: FeSO4 (0.1mM), H2 O2 (0.5mM), or FeSO4  + H2 O2 (Fenton system), in the presence or absence of Desferal. The application of Desferal in the incubation medium had a protective effect against FeSO4  + H2 O2 -induced sperm damage, namely, decrease of LPO; decrease the quantity of immotile spermatozoa and decrease the number of morphological abnormalities, regardless of the used medium. In experiment 2, the presence of FeSO4 in the incubation medium induced LPO in the same range as the combination FeSO4  + H2 O2 , in which the effect was reduced by Desferal. Thus, the supplement of Desferal to media used for sperm storage and processing could be a useful tool for diminishing oxidative injury and improving the quality of the semen.

The quality of sperm preparation medium affects the motility, viability, and DNA integrity of human spermatozoa

AIM:

The goal was to compare the effects of three different sperm preparation media on sperm motility, viability, and DNA integrity of semen samples from normozoospermic men.

METHODS:

A total of 15 normozoospermic males were included in the study. The semen analysis (SA) was performed in accordance with the WHO guidelines (2010). After SA, each sample was divided into three aliquots, and swim-up was performed with three different sperm preparation media (Sperm Preparation Media, Origio, Denmark; Ham's F10, Biochrome, Berlin, Germany; and VitaSperm™, Innovative Biotech, Iran). Sperm motility, viability, and DNA fragmentation were evaluated at 0, 1, 2, and 24 h after swim-up.

RESULTS:

There were no significant differences, at any time intervals, in the total sperm motility between the different sperm preparation media. However, the rate of progressive motility was significantly higher in spermatozoa prepared using the media from Origio in comparison with VitaSperm™ (P = 0.03), whereas no significant difference was found against Ham's F10 medium. No significant differences in sperm viability were seen between the media products. However, 1 h after swim-up, the extent of sperm DNA fragmentation was lower in the medium from Origio versus VitaSperm™ (P = 0.02).

CONCLUSIONS:

The data showed that the quality of medium for preparation of semen samples from normozoospermic men significantly affects the performance of spermatozoa in assisted conception programs.

Effect of oxidative stress on male reproduction

Infertility affects approximately 15% of couples trying to conceive, and a male factor contributes to roughly half of these cases. Oxidative stress (OS) has been identified as one of the many mediators of male infertility by causing sperm dysfunction. OS is a state related to increased cellular damage triggered by oxygen and oxygen-derived free radicals known as reactive oxygen species (ROS). During this process, augmented production of ROS overwhelms the body's antioxidant defenses. While small amounts of ROS are required for normal sperm functioning, disproportionate levels can negatively impact the quality of spermatozoa and impair their overall fertilizing capacity. OS has been identified as an area of great attention because ROS and their metabolites can attack DNA, lipids, and proteins; alter enzymatic systems; produce irreparable alterations; cause cell death; and ultimately, lead to a decline in the semen parameters associated with male infertility. This review highlights the mechanisms of ROS production, the physiological and pathophysiological roles of ROS in relation to the male reproductive system, and recent advances in diagnostic methods; it also explores the benefits of using antioxidants in a clinical setting.

The role of oxidative stress and antioxidants in male fertility

Oxidative stress results from the imbalance between production of the reactive oxygen species (ROS) and the protective effect of the antioxidant system responsible for their neutralization and removal. An excess of ROS causes a pathological reaction resulting in damage to cells and tissues. Spermatozoa are particularly vulnerable to the harmful effects of ROS. Oxidative stress affects their activity, damages DNA structure, and accelerates apoptosis, all of which consequently decrease their numbers, hinders motility and development of normal morphology, and impairs function. This leads to disturbances in fertility or embryo development disorder. The main cellular source of ROS in the semen are immature sperm cells and white blood cells. The increase in the number of leukocytes may be due to infection and inflammation, but can also be secondary to harmful environmental factors, long sexual abstinence, or varicocele. The protective antioxidant system in the semen is composed of enzymes, as well as nonenzymatic substances, which closely interact with each other to ensure optimal protection against ROS. Non–enzymatic antioxidants include vitamins A, E, C, and B complex, glutathione, pantothenic acid, coenzyme Q10 and carnitine, and micronutrients such as zinc, selenium, and copper. It seems that a deficiency of any of them can cause a decrease in total antioxidant status. In vitro and in vivo that studies demonstrate many antioxidants possess a beneficial effect on fertility and, therefore, their use is recommended as supportive therapy for the treatment of infertility in men.

Sperm processing by swim-up and density gradient is effective in elimination of sperm with DNA damage

PURPOSE

DNA damage may occur during sperm processing, thereby negatively influencing fertilizing ability of the sperm. The present study was designed to compare the effectiveness of gradient and swim-up, either alone or in combination, to eliminate sperm with DNA damage.

METHODS

A total of 51 subjects visiting the University infertility clinic with normozoospermic parameters, oligozoospermia and teratozoospermia were included. Semen characteristics were analysed by standard criteria; Terminal deoxy nucelotidyl transferase mediated dUTP nick end labeling assay was employed for DNA damage assessment.

RESULTS

The percentage of TUNEL positive sperm after sperm processing was significantly lower in normozoospermic (P < 0.05), oligozoospermic (P < 0.001) and teratozoospermic samples (P < 0.01). No difference was observed in the incidence of TUNEL positive sperm between the various techniques, suggesting that they are comparable.

CONCLUSIONS

Sperm preparation has been found to result in enrichment of sperm with intact chromatin, which is likely to improve the chances of achieving a viable pregnancy.

The role of antioxidant therapy in the treatment of male infertility: an overview

In recent years, many studies have focused on the effect of oxidative stress, reactive oxygen species (ROS) and antioxidants on the male eproductive system. Under physiological conditions, sperm produces small amounts of ROS, which are needed for fertilisation, acrosome reaction and capacitation. However, if an increased production of ROS is not associated with a similar increase in scavenging systems, peroxidative damage of the sperm plasma membrane and loss of DNA integrity typically occur, which leads to cell death and reduced fertility. Furthermore, since there is no linear correlation between sperm quality and pregnancy rates, an improvement in semen parameters should not be the sole outcome considered in studies of antioxidant therapies. A definitive conclusion regarding the benefit of these therapies is difficult to obtain, as most of the previous studies lacked control groups, considered different antioxidants in different combinations and doses, or did not evaluate pregnancy rates in previously infertile couples. Even if beneficial effects were reported in a few cases of male infertility, more multicentre, double-blind studies performed with the same criteria are necessary for an increased understanding of the effects of various antioxidants on fertility.

Antioxidant therapy in male infertility: fact or fiction?

Infertile men have higher levels of semen reactive oxygen species (ROS) than do fertile men. High levels of semen ROS can cause sperm dysfunction, sperm DNA damage and reduced male reproductive potential. This observation has led clinicians to treat infertile men with antioxidant supplements. The purpose of this article is to discuss the rationale for antioxidant therapy in infertile men and to evaluate the data on the efficacy of dietary and in vitro antioxidant preparations on sperm function and DNA damage. To date, most clinical studies suggest that dietary antioxidant supplements are beneficial in terms of improving sperm function and DNA integrity. However, the exact mechanism of action of dietary antioxidants and the optimal dietary supplement have not been established. Moreover, most of the clinical studies are small and few have evaluated pregnancy rates. A beneficial effect of in vitro antioxidant supplements in protecting spermatozoa from exogenous oxidants has been demonstrated in most studies; however, the effect of these antioxidants in protecting sperm from endogenous ROS, gentle sperm processing and cryopreservation has not been established conclusively.

Washing increases the susceptibility to exogenous oxidative stress in red deer spermatozoa

The effects of routine sperm work are often overlooked. We assessed the effect of washing cryopreserved epididymal spermatozoa from red deer (Cervus elaphus hispanicus, Helzheimer 1909). After thawing, epididymal samples (four stags) were diluted in TALP-HEPES. A split was left untouched, another was centrifuged (300 x g, 5 min) and resuspended, and a third was centrifuged and the supernatant substituted by fresh TALP-HEPES (washing). Each split was supplemented either with nothing, 1mM of the antioxidant Trolox, 100 microM of the oxidant Fe (with ascorbate), or both. The 3x4 treatments were incubated at 37 degrees C and assessed each hour up to 3h for motility (computer-aided sperm assessment) and viability/apoptosis plus mitochondrial status (YO-PRO-1, propidium iodide, Mitotracker Deep Red; flow cytometry). DNA damage at 4h was assessed using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay. Centrifugation alone affected neither sperm quality nor DNA, and the oxidant had no effect in control or centrifuged samples. Washed samples were not different than control, but oxidant decreased motility, mitochondrial status and viability, and altered the motility subpopulation pattern, being partially suppressed by Trolox. Spermatozoa with damaged DNA dramatically increased in the washed-oxidized sample (from 22.30+/-3.52% to 67.94+/-5.07%), but not when antioxidant was present. Although samples from different males behaved similarly, male-to-male variability was detected regarding susceptibility to oxidative damage after washing. We concluded that, although red deer thawed spermatozoa seemed resilient to centrifugation, the vulnerability to oxidative stress after washing makes it advisable to supplement manipulation media with antioxidants, especially taking into account male-to-male variability.

Assessment of the cryopreservation of equine spermatozoa in the presence of enzyme scavengers and antioxidants

OBJECTIVE

To evaluate the effect of the addition of enzyme scavengers and antioxidants to the cryopreservation extender on characteristics of equine spermatozoa after freezing and thawing.

SAMPLE POPULATION

2 ejaculates collected from each of 5 stallions.

PROCEDURE

Equine spermatozoa were cryopreserved in freezing extender alone (control samples) or with the addition of catalase (200 U/mL), superoxide dismutase (200 U/mL), reduced glutathione (10 mM), ascorbic acid (10 mM), alpha-tocopherol (25, 50, 100, or 500 microM or 1 mM), or the vehicle for alpha-tocopherol (0.5% ethanol). After thawing, spermatozoal motility was assessed via computer-assisted analysis and DNA fragmentation was assessed via the comet assay. Spermatozoal mitochondrial membrane potential, acrosomal integrity, and viability were determined by use of various specific staining techniques and flow cytometry.

RESULTS

The addition of enzyme scavengers or antioxidants to cryopreservation extender did not improve spermatozoal motility, DNA fragmentation, acrosomal integrity, viability, or mitochondrial membrane potential after thawing. Superoxide dismutase increased DNA fragmentation, likely because of the additional oxidative stress caused by the generation of hydrogen peroxide by this enzyme. Interestingly, the addition of the vehicle for alpha-tocopherol resulted in a significant decrease in live acrosome-intact spermatozoa.

CONCLUSIONS AND CLINICAL RELEVANCE

The addition of antioxidants to the cryopreservation extender did not improve the quality of equine spermatozoa after thawing, which suggests that the role of oxidative stress in cryopreservation-induced damage of equine spermatozoa requires further investigation. Our data suggest that solubilizing alpha-tocopherol in ethanol may affect spermatozoal viability; consequently, water-soluble analogues of alpha-tocopherol may be preferred for future investigations.

Sperm function and assisted reproduction technology

The evaluation of different functional sperm parameters has become a tool in andrological diagnosis. These assays determine the sperm's capability to fertilize an oocyte. It also appears that sperm functions and semen parameters are interrelated and interdependent. Therefore, the question arose whether a given laboratory test or a battery of tests can predict the outcome in in vitro fertilization (IVF). One-hundred and sixty-one patients who underwent an IVF treatment were selected from a database of 4178 patients who had been examined for male infertility 3 months before or after IVF. Sperm concentration, motility, acrosin activity, acrosome reaction, sperm morphology, maternal age, number of transferred embryos, embryo score, fertilization rate and pregnancy rate were determined. In addition, logistic regression models to describe fertilization rate and pregnancy were developed. All the parameters in the models were dichotomized and intra- and interindividual variability of the parameters were assessed. Although the sperm parameters showed good correlations with IVF when correlated separately, the only essential parameter in the multivariate model was morphology. The enormous intra- and interindividual variability of the values was striking. In conclusion, our data indicate that the andrological status at the end of the respective treatment does not necessarily represent the status at the time of IVF. Despite a relatively low correlation coefficient in the logistic regression model, it appears that among the parameters tested, the most reliable parameter to predict fertilization is normal sperm morphology. (Reprod Med Biol 2005; 4: 7-30).

Oxidative stress and its implications in female infertility – a clinician's perspective

Reactive oxygen species (ROS) have a role in the modulation of gamete quality and gamete interaction. Generation of ROS is inherent in spermatozoa and contaminating leukocytes. ROS influence spermatozoa, oocytes, embryos and their environment. Oxidative stress (OS) mediates peroxidative damage to the sperm membrane and induces nuclear DNA damage. ROS can modulate the fertilizing capabilities of the spermatozoa. There is extensive literature on OS and its role in male infertility and sperm DNA damage and its effects on assisted reproductive techniques. Evidence is accumulating on the role of ROS in female reproduction. Many animal and human studies have elucidated a role for ROS in oocyte development, maturation, follicular atresia, corpus luteum function and luteolysis. OS-mediated precipitation of pathologies in the female reproductive tract is similar to those involved in male infertility. OS influences the oocyte and embryo quality and thus the fertilization rates. ROS appears to play a significant role in the modulation of gamete interaction and also for successful fertilization to take place. ROS in culture media may impact post-fertilization development, i.e. cleavage rate, blastocyst yield and quality (indicators of assisted reproduction outcomes). OS is reported to affect both natural and assisted fertility. Antioxidant strategies should be able to intercept both extracellular and intracellular ROS. This review discusses the sources of ROS in media used in IVF-embryo transfer and strategies to overcome OS in oocyte in-vitro maturation, in-vitro culture and sperm preparation techniques.

Role of antioxidants in treatment of male infertility: an overview of the literature

Seminal oxidative stress in the male reproductive tract is known to result in peroxidative damage of the sperm plasma membrane and loss of its DNA integrity. Normally, a balance exists between concentrations of reactive oxygen species and antioxidant scavenging systems. One of the rational strategies to counteract the oxidative stress is to increase the scavenging capacity of seminal plasma. Numerous studies have evaluated the efficacy of antioxidants in male infertility. In this review, the results of different studies conducted have been analysed, and the evidence available to date is provided. It was found that although many clinical trials have demonstrated the beneficial effects of antioxidants in selected cases of male infertility, some studies failed to demonstrate the same benefit. The majority of the studies suffer from a lack of placebo-controlled, double-blind design, making it difficult to reach a definite conclusion. In addition, investigators have used different antioxidants in different combinations and dosages for varying durations. Pregnancy, the most relevant outcome parameter of fertility, was reported in only a few studies. Most studies failed to examine the effect of antioxidants on a specific group of infertile patients with high oxidative stress. Multicentre, double-blind studies with statistically accepted sample size are still needed to provide conclusive evidence on the benefit of antioxidants as a treatment modality for patients with male infertility.

Sperm preparation for ART

The onset of clinical assisted reproduction, a quarter of a century ago, required the isolation of motile spermatozoa. As the indication of assisted reproduction shifted from mere gynaecological indications to andrological indications during the years, this urged andrological research to understand the physiology of male germ cell better and develop more sophisticated techniques to separate functional spermatozoa from those that are immotile, have poor morphology or are not capable to fertilize oocytes. Initially, starting from simple washing of spermatozoa, separation techniques, based on different principles like migration, filtration or density gradient centrifugation evolved. The most simple and cheapest is the conventional swim-up procedure. A more sophisticated and most gentle migration method is migration-sedimentation. However, its yield is relatively small and the technique is therefore normally only limited to ejaculates with a high number of motile spermatozoa. Recently, however, the method was also successfully used to isolate spermatozoa for intracytoplasmic sperm injection (ICSI). Sperm separation methods that yield a higher number of motile spermatozoa are glass wool filtration or density gradient centrifugation with different media. Since Percoll as a density medium was removed from the market in 1996 for clinical use in the human because of its risk of contamination with endotoxins, other media like IxaPrep, Nycodenz, SilSelect, PureSperm or Isolate were developed in order to replace Percoll. Today, an array of different methods is available and the selection depends on the quality of the ejaculates, which also includes production of reactive oxygen species (ROS) by spermatozoa and leukocytes. Ejaculates with ROS production should not be separated by means of conventional swim-up, as this can severely damage the spermatozoa. In order to protect the male germ cells from the influence of ROS and to stimulate their motility to increase the yield, a number of substances can be added to the ejaculate or the separation medium. Caffeine, pentoxifylline and 2-deoxyadenosine are substances that were used to stimulate motility. Recent approaches to stimulate spermatozoa include bicarbonate, metal chelators or platelet-activating factor (PAF). While the use of PAF already resulted in pregnancies in intrauterine insemination, the suitability of the other substances for the clinical use still needs to be tested. Finally, the isolation of functional spermatozoa from highly viscous ejaculates is a special challenge and can be performed enzymatically to liquefy the ejaculate. The older method, by which the ejaculate is forcefully aspirated through a narrow-gauge needle, should be abandoned as it can severely damage spermatozoa, thus resulting in immotile sperm.

Superoxide dismutase activities of spermatozoa and seminal plasma are not correlated with male infertility

Abnormal reactive oxygen species (ROS) production is associated with defective sperm function. Superoxide dismutase (SOD) is related with the scavenging of seminal ROS. We aimed to determine the effect of SOD activities of spermatozoa and seminal plasma on sperm quality. Semen samples from infertile couples who consented to the analyses were divided into two groups: 1) normospermia (n = 20); and 2) oligoasthenozoospermia (n = 31). The SOD activities of the spermatozoa and seminal plasma were measured by determining the inhibition of pyrogallol autoxidation. The SOD activities of spermatozoa and seminal plasma in both groups were compared. The relationships between the SOD activities and the sperm qualities were determined. We noted that SOD activities of sperm/seminal plasma in both groups were nonsignificantly different (group 1 vs. 2 = 0.77 +/- 0.33/0.84 +/- 0.40 U/mg protein for sperm, and 0.66 +/- and 0.36/0.83 +/- 0.47 U/ml for seminal plasma). SOD activities of sperm/seminal plasma were positively but nonsignificantly correlated with the sperm motility (SOD of sperm = 0.0008 x motility + 0.67; SOD of seminal plasma = 0.0006 x motility + 0.81) and concentration (SOD of sperm = 0.0006 x concentration + 0.67; SOD of seminal plasma = 0.0021 x concentration + 0.73). We concluded that SOD activities of sperm and seminal plasma were nonsignificantly correlated with the seminal quality. It appears that the SOD survey is not a useful tool for determining sperm fertilization potential.

Human sperm immobilizing activity of aminophenyl arsenic acid and its N-substituted quinazoline, pyrimidine, and purine derivatives: protective effect of glutathione

We examined the potential toxicity of pentavalent organic arsenicals for human sperm. We used computer-assisted sperm analysis to examine the effects of three aminophenyl arsenicals and their nine N-substituted quinazoline, pyrimidine, and purine derivatives on human sperm motility and kinematics in human semen and medium. Among the arsenicals examined, (aminophenylazo)-phenyl arsonic acid and its N-substituted pyrimidine derivative PHI-370 (2-methylthio-4-[(4'-aminophenylazo)-phenylarsonic acid] pyrimidine) exhibited rapid sperm immobilizing activity in medium with EC(50) values of 77 and 82 microM, respectively, and t(1/2) of < 3 min. Molecular modeling analysis indicated that sperm-immobilizing organic arsenicals exhibit high dipole moments (>7 Debyes). Sperm immobilizing activity of these arsenicals was completely abrogated in the presence of seminal plasma. Furthermore, coincubation of motile sperm with PHI-370 in the presence of reduced glutathione (GSH) resulted in dose-dependent protection of sperm motility and sperm motion parameters. Coincubation of the arsenical with GSH at a molar ratio of 1:20 resulted in 95% retention of sperm progressive motility. The mean values of the other sperm movement characteristics also showed > 90% protection. These observations suggest that the rapid sperm immobilizing activity of these pentavalent arsenicals may be as a result of direct binding of the arsenical with the sperm thiol components essential for sperm motility as well as induction of oxidative damage by disruption of sperm cell's antioxidant system. Sodium arsanilate and its N-substituted pyrimidine derivative, PHI-370, are useful probes to further evaluate the mechanism of pentavalent arsanilate-induced human sperm dysfunction.

Intracytoplasmic sperm injection in bovine: effects of oocyte activation, sperm pretreatment and injection technique

Intracytoplasmic sperm injection (ICSI) is a very important technique for treating male subfertility and for basic research. The efficiency of ICSI in bovine is very limited because of the necessity for additional oocyte activation before or after the ICSI procedure. In this study, we compared the effects of seven different protocols on activation and fertilization rates of bovine oocytes after ICSI and on their subsequent development under in vitro conditions. The protocols include 1) different chemical activation of oocytes, 2) pretreated or nonpretreated sperm, and 3) conventional or Piezo-driven injection techniques. In all three groups, ICSI, sham-injected, and noninjected, the highest activation rates were obtained after treatment of oocytes with ionomycin followed by 6-dimethylaminopurine (6-DMAP). Using this treatment for oocyte activation, 59% of oocytes were activated and 31% of oocytes were fertilized using dithiothreitol (DTT) pretreated spermatozoa and Piezo-driven injection. Using the protocols with the same oocyte activation or activation with calcium ionophore (Ca-I) and cycloheximide (CHX), nonpretreated sperm, and conventional injection technique, early cleavage rate (79.6% and 77.6%, respectively) were significantly (P <0.01) higher when compared with all other protocols. The latter protocol resulted in 8% blastocyst and 90% of the obtained blastocysts were found to be diploid. Our results demonstrate that activation of oocytes, sperm treatment, and injection technique separately or together could improve the success of bovine ICSI.

Viability, susceptibility to peroxidation and fatty acid composition of boar semen during liquid storage

The changes in viability, susceptibility to peroxidation and fatty acid composition of total phospholipid were studied in boar spermatozoa during 5 day liquid storage in a standard or alpha-tocopherol (alphaT) enriched diluent. The sperm rich fraction of the ejaculates was collected from 6-month old boars. Sperm viability progressively decreased during storage and alphaT inclusion into the diluent significantly inhibited this trend. alphaT inclusion also decreased significantly peroxidation (TBARS production of spermatozoa). Spermatozoa stored in the treatment diluent became rapidly enriched in alphaT with a concomitant decrease of alphaT content in the medium. The proportion of polyunsaturates, mainly 22:6n-3, decreased with a complementary increase in the content of the saturates, mainly 18:0. The inclusion of alphaT into the diluent was effective in totally preventing the significant decrease of 22:6n-3 observed in sperm phospholipid in the control samples during the storage period. It is concluded that the alphaT inclusion in the boar semen diluent increased cell viability through its prevention of an oxidative reduction in the levels of the major polyunsaturated fatty acids, namely 22:6n-3.

Effect of exogenous glutathione on the in vitro fertilization of bovine oocytes

Increased amounts of reactive oxygen species (ROS) during in vitro culture may cause cytotoxic damage to gametes and embryos. The main purpose of this study was to investigate the effect of glutathione (GSH), a ROS scavenger, supplemented during IVF of bovine oocytes on embryo development using spermatozoa from different bulls. The following experiments were performed: 1) matured COCs were fertilized in the absence or presence of 1 mM GSH using semen from 4 bulls (Bulls A, B, C and D); 2) matured COCs were fertilized in the absence or presence of 1 mM GSH using semen from Bull C to examine sperm penetration, pronuclear formation and apposition; 3) COCs were fertilized with in the presence of either 0, 0.1, 1.0 or 10 mM GSH to examine the effect of GSH concentration using sperm from Bull C; 4) concentrations of GSH were measured both in the medium and in the oocytes during IVF. Glutathione at 1 mM in IVF medium affected the blastocyst formation, but not the cleavage rate. The effect on blastocyst formation was bull dependent: semen from Bull B and D had a negative, that from Bull C a positive and the one from Bull A no effect. The positive effect of Bull C semen increased the rate of blastocyst formation from 20.1 to 27.3% in control and GSH-treated samples, respectively. The increased rate was due to more zygotes reaching the 8-cell or greater stage by Day 4 after IVF. There was no change in the fertilization or cleavage rates. The GSH was still stable after 18 h incubation in IVF medium, and there was a dose-dependent increase in the GSH concentration in the oocytes. It is concluded that the effect of GSH during IVF on the proportion of blastocysts is dependent on both bull and GSH concentration.

Sperm separation in patients with urogenital infections

A total of 196 patients attending the Center of Dermatology and Andrology, Giessen, Germany, were examined for fertility problems. Polymorphonuclear elastase, reactive oxygen species (ROS) and the number of round and peroxidase-positive cells were investigated in addition to routine semen analysis. The ejaculates were also analysed before and after sperm separation by means of swim-up or glass wool filtration. In 20 cases of leukocytospermia, sperm concentration, motility, viability, production of reactive oxygen species, and the number of peroxidase-positive cells were evaluated before and after glass wool filtration. The results show that ROS production by viable spermatozoa is highly correlated with the concentration of PMN elastase and the number of both peroxidase-positive and round cells. Multiple regression analysis with motility as dependent parameter showed the number of round cells (n = 91; r = -0.332; P = 0.0030) to be the most important parameter affecting motility, while ROS mainly affects the viability of spermatozoa (n = 69; r = 0.250; P = 0.0107). In the case of leukocytospermia, glass wool filtration significantly reduced the number of peroxidase-positive cells and ROS production (P = 0.0098 and P = 0.0005, respectively). Receiver operating characteristic (ROC) curve analysis for ROS production in the ejaculate using a concentration of 1.000 ng ml-1 PMN elastase as decisive parameter resulted in a cut-off value of 49,489.9 counts 10(-7) viable spermatozoa. The statistical parameters were: Sensitivity: 63.2%, specificity: 100%, positive predictive value: 100%, negative predictive value: 36.1%.

Susceptibility of human sperm to in situ DNA denaturation is strongly correlated with DNA strand breaks identified by single-cell electrophoresis

Susceptibility of mammalian sperm DNA to low pH- or heat-induced denaturation in situ has shown very strong dose-response relationships with animal and human exposure to chemical and physical toxicants and also fertility potential. In this study, 23 human semen samples representing a wide range in percentage (7-86%) of sperm exhibiting abnormally high susceptibility of DNA in situ to denaturation were studied for the integrity of their DNA using alkaline comet assay (single-cell microgel electrophoresis, pH 10.0). The percentage of comets observed for these samples ranged from 5 to 95%; these data correlated strongly with the percentage of sperm with increased DNA denaturability (r = 0.973; P < 0.001). Labeling of 3' ends of nicked DNA sites with 5-bromo-2'-deoxyuridine 5'-triphosphate (BrdUTP) followed by tagging with FITC-BrdUTP monoclonal antibody and flow cytometry also indicated significantly strong correlations of BrdUTP incorporation with both abnormal susceptibility of DNA to denaturation (r = 0.859, P < 0.001) and comet assay (r = 0.812, P < 0.001). The relationship among susceptibility of sperm chromatin to acid denaturation in situ, BrdUTP incorporation, and formation of comets suggests that DNA fragmentation monitored by these assays may have important physiological relevance in terms of sperm quality and fertility potential.

Scavenging effect of N-acetyl-L-cysteine against reactive oxygen species in human semen: a possible therapeutic modality for male factor infertility?

A new approach to reduce the level of reactive oxygen species (ROS) in human semen by using N-acetyl-L-cysteine (NAC) was evaluated. Semen samples were incubated with or without NAC (1.0 mg ml-1) at room temperature. The chemiluminescent signal of the oxidation of luminol was detected by means of an MTP reader after 0, 20, 40, 60 and 120 min, respectively, using 200 microM luminol. In addition, the dose-dependent action of NAC (0.1, 1.0 and 5.0 mg ml-1) and the influence of NAC on functional sperm parameters (motility and acrosome reaction) were studied. ROS levels decreased significantly after 20 min incubation with NAC. This reduction was greater in the high ROS group (> 30000 counts/10(7) viable sperm at t = 0) than in the low ROS group (< 30000). In addition, a marked dose-dependence of NAC was observed. Concerning sperm function, total sperm motility improved after incubation with NAC, but no significant change was observed with respect to the acrosome reaction. NAC (at concentrations of 1.0 mg ml-1) significantly reduced ROS in human semen and showed the possibility of improving impaired sperm function. After further testing NAC might be useful for the treatment of male infertility patients.

Functional motion changes during sperm transit to the site of fertilization and in-vitro applications: a review

Continued research to define the parameters of sperm function should aid the evaluation of various approaches in infertility as well as the efficacy of contraceptives for men which do not necessarily achieve azoospermia. Many treatment forms have been advocated for male factor infertility but have yielded little effect. These included, for example, gonadotrophins, clomiphene citrate, the weakly androgenic steroid, mesterolone. Often, improvements in oligoasthenozoospermia that are not related to genital infection, do not attain normozoospermic levels. Owing to lack of success with various treatment modalities, assisted reproductive technology encompassing artificial insemination by husband or donor following in vitro enhancement of sperm function have assumed an important role in male infertility. Agents that have been shown to induce and support sperm capacitation processes such as hyperactivation, could serve an important role. These include human follicular fluid (HFF), maternal serum, fetal cord serum and methyl xanthine derivatives.