Oxidative stress and male infertility

BackgroundBetween 30% and 80% of patients with male infertility produce excessive reactive oxygen species (ROS) in their ejaculate even though the cause of male infertility is unexplained in approximately half of cases. The strong connection between oxidative stress (OS) and male infertility has led recent investigators to propose the term “Male Oxidative Stress Infertility (MOSI)” to describe OS‐associated male infertility.MethodsWe searched the PubMed database for original and review articles to survey the effects of OS on male infertility, and then verified the effects and treatments.Main findingsSeminal plasma contains many antioxidants that protect sperm from ROS, because low amounts of ROS are required in the physiological fertilization process. The production of excessive ROS causes OS which can lower fertility through lipid peroxidation, sperm DNA damage, and apoptosis. Several assays are available for evaluating OS, including the MiOXSYS® analyzer to measure oxidation‐reduction potential. Several measures should be considered for minimizing OS and improving clinical outcomes.ConclusionAccurately diagnosing patients with MOSI and identifying highly sensitive biomarkers through proteomics technology is vital for better clinical outcomes.     

Effect of serum antioxidant levels on sperm function in infertile male

Antioxidant and reactive oxygen species (ROS) has been implicated in male infertility. Antioxidants are compounds which scavenge formation or oppose of the actions ROS. Spermatozoa are particularly vulnerable to ROS because of inherent deficiencies in intracellular antioxidant enzyme protection, thus total body antioxidant capacity become more substantial to protect sperm. In this study to try to evaluate the role of serum total antioxidant capacity, uric acid, glutathione, total thiols, ferritin, albumin and malodialdehyde in male infertility. 66 men included in this study 40 were infertile and 26 were healthy fertile. Results showed a significant decrease in sperm progressive motility and a significant increase in sperm tail abnormality, also there were a significant decrease in serum total antioxidant capacity, uric acid and albumin in infertile group. Because of lack of the intracellular antioxidant enzymes sperm cannot protect plasma membrane that surrounds the tail, the protection depends on the antioxidant defense afforded by the seminal plasma and on the entire body antioxidant capacity. Decrease of serum antioxidant capacity, uric acid and albumin may cause destroy of sperm tail membrane and this may lowering of sperm progressive motility.     

Carnitines and male infertility

L-Carnitine (LC) and acetyl-L-carnitine (ALC) are highly concentrated in the epididymis and play a crucial role in sperm metabolism and maturation. They are related to sperm motility and have antioxidant properties. The objective of this review is to summarize the multiple roles played by LC and ALC in male reproduction, and to highlight their limitations as well as their benefits in the treatment of male infertility. A variety of studies support the conclusion that LC and/or ALC at total daily amounts of at least 3 g per day can significantly improve both sperm concentration and total sperm counts among men with astheno- or oligoasthenozoospermia. Although many clinical trials have demonstrated the beneficial effects of LC and ALC in selected cases of male infertility, the majority of these studies suffer from a lack of placebo-controlled, double blind design, making it difficult to reach a definite conclusion. Additional, well-designed studies are necessary to further validate the use of carnitines in the treatment of patients with male infertility, specifically in men with poor semen quality.     

A randomised control trial examining the effect of an antioxidant (Menevit) on pregnancy outcome during IVF-ICSI treatment

BACKGROUND: Evidence has accumulated supporting the role of reactive oxygen species (ROS) in the pathogenesis of sperm dysfunction among men with infertility. Damage to sperm DNA by ROS can lead to failure of conception, miscarriage or potentially even childhood cancer. The objective of this study was to examine the effect of male antioxidant treatment on embryo quality and pregnancy outcome during in vitro fertilisation-intracytoplasmic sperm injection (IVF-ICSI) treatment. METHODS: Sixty couples with severe male factor infertility were enrolled in a prospective randomised double-blind placebo-controlled trial. Male participants were randomly assigned to take either one capsule per day of the Menevit antioxidant or an identical in appearance placebo for three months prior to their partner's IVF cycle. The primary outcome was cleavage stage embryo quality and the secondary outcomes were oocyte fertilisation rate, pregnancy rates and treatment side-effects. Approval by the local Human Research Ethics Committee was obtained prior to the commencement of this study. RESULTS: The antioxidant group recorded a statistically significant improvement in viable pregnancy rate (38.5% of transferred embryos resulting in a viable fetus at 13 weeks gestation) compared to the control group (16% viable pregnancy). No significant changes in oocyte fertilisation rate or embryo quality were detected between the antioxidant and the placebo groups. Side-effects on the Menevit antioxidant were rare (8%) and mild in nature. CONCLUSIONS: The Menevit antioxidant appears to be a useful ancillary treatment that significantly improves pregnancy rates in couples undergoing IVF-ICSI treatment for severe male factor infertility.     

Reactive oxygen species measurement in neat and washed semen: comparative analysis and its significance in male infertility assessment

Purpose  

Oxidative stress (OS) is a major concern in idiopathic male infertility as elevated levels of reactive oxygen species (ROS) in the semen is believed to adversely affect sperm functional competence and damage both nuclear and mitochondrial DNA. Therefore, identifying infertile men with seminal OS may be used as a valuable tool in the assessment of male infertility. Semen is a complex mixture of spermatozoa and seminal plasma which is rich in enzymatic and non-enzymatic antioxidants. However, the measurement of ROS in the semen and its application in male infertility assessment is poorly understood.     

Antioxidants to reduce sperm DNA fragmentation: an unexpected adverse effect

Reactive oxygen species (ROS) have a negative impact on sperm DNA, leading to the formation of oxidative products such as 8-oxo-7,8-dihydroxyguanosine. This compound causes fragmentation and, thus, has a mutagenic effect. Patient treatment with oral antioxidant vitamins is, therefore, standard practice for male infertility, in an attempt to decrease formation of ROS and improve fertility. In this study, the DNA fragmentation index and the degree of sperm decondensation were measured using the sperm chromatin structure assay before and after 90 days treatment with antioxidant vitamins associated with zinc and selenium. Antioxidant treatment led to a decrease in sperm DNA fragmentation (-19.1%, P < 0.0004), suggesting that at least part of the decay was linked to ROS. However, it also led to an unexpected negative effect: an increase in sperm decondensation with the same order of magnitude (+22.8%, P < 0.0009). The opening of interchain disulphide bridges in protamines may explain this aspect, as antioxidant vitamins, especially vitamin C, are able to open the cystin net, thus interfering with paternal gene activity during preimplantation development. This observation might explain the discrepancy observed concerning the role of these antioxidant treatments in improving male fertility.     

Observation of spermatozoa by a high-magnification microscope

Semen analyses are the primary tool for evaluating male infertility, as semen parameters are useful for predicting potential fertility. In the field of assisted reproductive technology (ART), the single best motile spermatozoon should be selected, especially when performing intracytoplasmic sperm injection (ICSI). In this context, the motile sperm organelle morphology examination (MSOME) was developed as a method of assessing the detailed morphology of motile spermatozoa in real time at a magnification of up to 6,300× on a video system. The use of ICSI with MSOME-selected sperm is called intracytoplasmic morphologically selected sperm injection (IMSI). IMSI improves the outcomes of ICSI. MSOME can be also applied to evaluate male infertility. Among MSOME parameters, the presence of sperm nuclear vacuoles is the most important finding. Large sperm nuclear vacuoles (LNV) are related not only to poor ART outcomes, but also to poor semen quality and sperm DNA damage, such as DNA fragmentation and chromatin condensation failure. It has been suggested that sperm head vacuoles are produced at earlier stages of sperm maturation. It is possible that the number of LNV can be decreased by surgical or medical treatment for male infertility. Therefore, the level of LNV has the potential to be used as an alternative parameter of semen quality and a new tool for evaluating the therapeutic effects of treatment in male patients with infertility.     

Relationship between male reproductive hormones, sperm DNA damage and markers of oxidative stress in infertility

This study investigated the relationship between male reproductive hormones and sperm DNA damage and markers of oxidative stress in men undergoing infertility evaluation for male factor (n = 66) and non-male factor (n = 63) infertility. Semen samples were analysed for DNA fragmentation index (DFI). Serum samples were analysed for FSH, inhibin B, anti-Müllerian hormone (AMH), testosterone and total antioxidant capacity (TAC). Serum inhibin B was significantly lower in the male factor group compared with the non-male factor group. Inhibin B showed a positive correlation with sperm concentration and motility, and serum AMH showed a positive correlation with sperm concentration and semen volume. DFI was 3-fold higher in the male factor group and showed a negative correlation with sperm motility. Blood plasma TAC was negatively related to sperm concentration. The results confirm that AMH and inhibin B are markers of Sertoli cell function. Sperm DNA damage is moderately increased in male factor infertility, and is negatively associated with sperm motility. A negative association between antioxidant activity and sperm concentration suggests that even minimal oxidative stress may influence sperm concentration. However, there was no significant relationship between hormone concentrations, sperm DNA damage and total antioxidant capacity, suggesting other mechanisms for sperm dysfunction.     

The role of intrauterine insemination in male infertility

Male infertility is a common condition and intrauterine insemination (IUI) is used to treat the mild to moderate forms. Male subfertility determination is usually based on routine semen analysis but recent publications have questioned its diagnostic and prognostic accuracy as well as the effectiveness of IUI itself, as a treatment modality. We carried out a structured review of the literature to assess the current evidence regarding the diagnosis of male infertility, the effectiveness and cost effectiveness of IUI in male infertility and factors that affect the outcome of IUI. There is still uncertainty regarding the criteria for diagnosing male infertility and predicting treatment outcome based on standard semen parameters. The presence of seminal defects compromises the outcome of IUI in comparison with unexplained infertility. The total motile sperm count (TMSC) appears to have a consistent, direct relationship with treatment outcome, but there is no definite predictive threshold for success. However, it is reasonable to offer IUI as first-line treatment if TMSC is greater than 10 million when balancing the risk and cost of alternate treatments, such as in vitro fertilization (IVF). Sperm DNA studies and sperm preparation techniques warrant further studies in order to establish their clinical relevance. There are limited data on the clinical and cost-effectiveness of IUI in male infertility and large high-quality randomized controlled trials are warranted. However the difficulties in organizing such a study, at the present time, are a matter for discussion.     

Micromanipulation of gametes and embryos in preimplantation genetic diagnosis and assisted fertilization.

Recent advances in micromanipulation and biopsy of gametes and embryos have made it possible to develop new approaches for early genetic diagnosis and prevention of genetic disease and for treatment of severe male-factor infertility. Preimplantation diagnosis of a number of X-linked and autosomal recessive disorders has been performed, using polar body sampling and blastomere biopsy, coupled with polymerase chain reaction. Blastocyst biopsy has also been performed in human embryos; however, there has been no clinical application so far. Existing data have not shown any detrimental effect of micromanipulation and biopsy involved in the preimplantation development of the human embryo. The existing experience on micromanipulation of gametes (zona-opening procedures, subzonal sperm insertion, and sperm microinjection into the ooplasm) has also demonstrated the clinical usefulness in assisted fertilization, suggesting a possible selective application of various micromanipulation techniques and their combinations in male infertility.     

The impact of sperm DNA damage in assisted conception and beyond: recent advances in diagnosis and treatment

Sperm DNA damage is a useful biomarker for male infertility diagnosis and prediction of assisted reproduction outcomes. It is associated with reduced fertilization rates, embryo quality and pregnancy rates, and higher rates of spontaneous miscarriage and childhood diseases. This review provides a synopsis of the most recent studies from each of the authors, all of whom have major track records in the field of sperm DNA damage in the clinical setting. It explores current laboratory tests and the accumulating body of knowledge concerning the relationship between sperm DNA damage and clinical outcomes. The paper proceeds to discuss the strengths, weaknesses and clinical applicability of current sperm DNA tests. Next, the biological significance of DNA damage in the male germ line is considered. Finally, as sperm DNA damage is often the result of oxidative stress in the male reproductive tract, the potential contribution of antioxidant therapy in the clinical management of this condition is discussed. DNA damage in human spermatozoa is an important attribute of semen quality. It should be part of the clinical work up and properly controlled trials addressing the effectiveness of antioxidant therapy should be undertaken as a matter of urgency.Sperm DNA damage is a useful biomarker for male infertility diagnosis and prediction of assisted reproduction outcomes. It is associated with reduced fertilization rates, embryo quality and pregnancy rates, and higher rates of spontaneous miscarriage and childhood diseases. With all of these fertility check points, it shows more promise than conventional semen parameters from a diagnostic perspective. Despite this, few infertility clinics use it routinely. This review provides a synopsis of the most recent studies from each of the authors, all of whom have major track records in the field of sperm DNA damage in the clinical setting. It explores current laboratory tests and the accumulating body of knowledge concerning the relationship between sperm DNA damage and clinical outcomes. The paper proceeds to discuss the strengths and weaknesses and clinical applicability of current sperm DNA fragmentation tests. Next, the biological significance of DNA damage in the male germ line is considered. Finally, as sperm DNA damage is often the result of increased oxidative stress in the male reproductive tract, the potential contribution of antioxidant therapy in the clinical management of this condition is discussed. As those working in this field of clinical research, we conclude that DNA damage in human spermatozoa is an important attribute of semen quality which should be carefully assessed in the clinical work up of infertile couples and that properly controlled trials addressing the effectiveness of antioxidant therapy should be undertaken as a matter of urgency.     

Proteomics,oxidative stress and male infertility

Oxidative stress has been established as one of the main causes of male infertility and has been implicated in many diseases associated with infertile men. It results from high concentrations of free radicals and suppressed antioxidant potential, which may alter protein expression in seminal plasma and/or spermatozoa. In recent years, proteomic analyses have been performed to characterize the protein profiles of seminal ejaculate from men with different clinical conditions, such as high oxidative stress. The aim of the present review is to summarize current findings on proteomic studies performed in men with high oxidative stress compared with those with physiological concentrations of free radicals, to better understand the aetiology of oxidative stress-induced male infertility. Each of these studies has suggested candidate biomarkers of oxidative stress, among them are DJ-1, PIP, lactotransferrin and peroxiredoxin. Changes in protein concentrations in seminal plasma samples with oxidative stress conditions were related to stress responses and to regulatory pathways, while alterations in sperm proteins were mostly associated to metabolic responses (carbohydrate metabolism) and stress responses. Future studies should include assessment of post-translational modifications in the spermatozoa as well as in seminal plasma proteomes of men diagnosed with idiopathic infertility.Oxidative stress, which occurs due to a state of imbalance between free radicals and antioxidants, has been implicated in most cases of male infertility. Cells that are in a state of oxidative stress are more likely to have altered protein expression. The aim of this review is to better understand the causes of oxidative stress-induced male infertility. To achieve this, we assessed proteomic studies performed on the seminal plasma and spermatozoa of men with high levels of oxidative stress due to various clinical conditions and compared them with men who had physiological concentrations of free radicals. A variety of sperm and seminal plasma proteins were found to be expressed either in abundance (over-expressed) or in a lesser amount (underexpressed), while other proteins were found to be unique either to men with oxidative stress or to men with a balanced ratio of antioxidants/free radicals. Each study included in this review suggested several proteins that could possibly act as biomarkers of oxidative stress-induced male infertility, such as protein DJ-1, PIP, lactotransferrin and peroxiredoxin. Pathway analysis performed in these studies revealed that the changes in seminal plasma proteins in men with oxidative stress could be attributed to stress responses and regulatory pathways, while changes in sperm proteins were linked to stress responses and metabolic responses. Subsequent studies could look into post-translational modifications in the protein profile of men with idiopathic infertility. We hope that the information in this review will contribute to a better understanding of the main causes of idiopathic male infertility.     

The role of intrauterine insemination in male infertility

Male infertility is a common condition and intrauterine insemination (IUI) is used to treat the mild to moderate forms. Male subfertility determination is usually based on routine semen analysis but recent publications have questioned its diagnostic and prognostic accuracy as well as the effectiveness of IUI itself, as a treatment modality. We carried out a structured review of the literature to assess the current evidence regarding the diagnosis of male infertility, the effectiveness and cost effectiveness of IUI in male infertility and factors that affect the outcome of IUI. There is still uncertainty regarding the criteria for diagnosing male infertility and predicting treatment outcome based on standard semen parameters. The presence of seminal defects compromises the outcome of IUI in comparison with unexplained infertility. The total motile sperm count (TMSC) appears to have a consistent, direct relationship with treatment outcome, but there is no definite predictive threshold for success. However, it is reasonable to offer IUI as first-line treatment if TMSC is greater than 10 million when balancing the risk and cost of alternate treatments, such as in vitro fertilization (IVF). Sperm DNA studies and sperm preparation techniques warrant further studies in order to establish their clinical relevance. There are limited data on the clinical and cost-effectiveness of IUI in male infertility and large high-quality randomized controlled trials are warranted. However the difficulties in organizing such a study, at the present time, are a matter for discussion.     

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.     

高通量基因芯片技术在男性生殖医学研究中的应用

无精子症、少精子症、弱精子症、畸形精子症是男性生殖医学的重要课题,致病因素极其复杂。由基因异常引起精子发生异常导致男性不育的占30%以上。利用基因芯片技术迅速、高通量、大规模等优点,可以深入研究精子发生、精子功能异常以及生殖毒理学机制,为男性不育的预防、诊断与治疗提供更加明确的理论依据。     

A preclinical evaluation of pronuclear formation by microinjection of human spermatozoa into human oocytes

In vitro fertilization (IVF) is recognized as an accepted treatment for male infertility. However, the fertilization rate is significantly lower than the fertilization rate of other IVF patient groups. Some male factor infertility patients still have a basic semen quality too poor for treatment by IVF. Microinjection of a spermatozoon directly into ooplasm has been recommended to assist fertilization in this subfertile population. This study found that oocytes from 5 of 11 patients microinjected with human spermatozoa demonstrated successful pronuclear formation and correlated with the incidence of pregnancy in these patients transferred with same-source oocytes inseminated by standard protocols. This initial evidence promotes the supposition of clinical feasibility of assisted fertilization by sperm microinjection.     

Novel method for the cryopreservation of testicular sperm and ejaculated spermatozoa from patients with severe oligospermia: a pilot study

OBJECTIVE: To investigate Volvox globator as an easy-to-handle vehicle and as a safe alternative for cryopreservation of functional motile sperm cells. DESIGN: Prospective, controlled, clinical pilot study. SETTING: Two in vitro fertilization (IVF) outpatient clinics for reproductive medicine. PATIENT(S): Fifteen patients with severe male infertility (density <100 motile sperm per milliliter) who were recruited from two IVF programs. The sperm cells were not intended for clinical use after thawing. INTERVENTION(S): In each case, a predetermined number (n = 8) of motile and morphologically intact sperm cells were injected into each Volvox sphere and then cryopreserved. The quality of the sperm cells and the handling of the Volvox spheres were verified. MAIN OUTCOME MEASURE(S): Postthaw recovery rate in cases of severe male infertility and the amount of motile sperm after thawing. RESULT(S): The postthaw recovery rate was 100%. At least 60% of the sperm cells were motile after thawing. CONCLUSION(S): The use of the spherical algae Volvox globator offers a promising, inexpensive, and easy approach to the cryopreservation of functional motile sperm cells. Volvox globator is an alternative in countries that prohibit the destructive use of oocytes, even after fertilization has failed.     

Surgical sperm retrieval for assisted reproduction

Intra-cytoplasmic sperm injection (ICSI) has revolutionized the treatment of male infertility by requiring only a single sperm to allow men whose infertility was previously considered to be uncorrectable to father a biological offspring. As a result, surgical sperm retrieval for assisted reproduction has developed to support this therapy. Microsurgical techniques have been applied to either identify areas of active spermatogenesis within the testis or to aspirate sperm-containing fluid or tissue. The combination of these techniques with in vitro fertilization (IVF)/ICSI has been shown to be a powerful approach to the treatment of azoospermic men. The availability of sperm cryopreservation offers an additional advantage, negating the need for synchronization of sperm retrieval and ovulation. Thus, the advanced methods for sperm retrieval discussed in this review also provide therapeutic options, as compared the traditional diagnostic testicular biopsy.