Evaluation of poly(ADP-ribose) polymerase cleavage (cPARP) in ejaculated human sperm fractions after induction of apoptosis

Gallic Acid Enhances Olaparib-Induced Cell Death and Attenuates Olaparib Resistance in Human Osteosarcoma U2OS Cell Line

Cancer remains one of the most formidable diseases globally and continues to be a leading cause of mortality. While chemotherapeutic agents are crucial in cancer treatment, they often come with severe side effects. Furthermore, the development of acquired drug resistance poses a significant challenge in the ongoing battle against cancer. Combining these chemotherapeutic agents with plant-derived phenolic compounds offers a promising approach, potentially reducing side effects and counteracting drug resistance. Phytochemicals, the bioactive compounds found in plants, exhibit a range of health-promoting properties, including anticarcinogenic, antimutagenic, antiproliferative, antioxidant, antimicrobial, neuroprotective, and cardioprotective effects. Their ability to enhance treatment, coupled with their non-toxic, multi-targeted nature and synergistic potential when used alongside conventional drugs, underscores the growing importance of natural therapeutics. In this study, we investigated the anticancer effects of olaparib (OL), a small-molecule PARP inhibitor that has shown promising results in both preclinical and clinical trials, and gallic acid (GA), a phenolic compound, in olaparib-resistant human osteosarcoma U2OS cells (U2OS-PIR). Both parental U2OS and U2OS-PIR cell lines were treated with increasing concentrations of olaparib and gallic acid, and their cytotoxic effects were assessed using the WST-1 cell viability assay. The synergistic potential of OL and GA, based on their determined IC50 values, was further explored in combination treatment. A colony survival assay revealed the combination's ability to significantly reduce the colony-forming capacity of cancer cells. Additionally, the apoptotic effects of OL and GA, both individually and in combination, were examined in U2OS-PIR cells using acridine orange/ethidium bromide dual staining. The anti-angiogenic properties were assessed through a VEGF ELISA, while the expression of proteins involved in DNA damage and apoptotic signaling pathways was analyzed via Western blot. The results of this study demonstrate that gallic acid effectively suppresses cell viability and colony formation, particularly when used in combination therapy to combat OL resistance. Additionally, GA inhibits angiogenesis and induces DNA damage and apoptosis by modulating key apoptosis-related proteins, including cPARP, Bcl-2, and Bax. These findings highlight gallic acid as a potential compound for enhancing therapeutic efficacy in overcoming acquired drug resistance.

Investigation of the efficacy of different cryoprotectants in the freezing of testicular tissue and epididymal sperm: Spermatological parameters, tissue viability and PARP-1 gene expression

The presented study covers testicular tissue and epididymal spermatozoa cryopreservation processes in bulls and aims to investigate the effects of these applications on spermatological parameters, cell viability in testicular tissue, and the expression of the PARP-1 gene, a DNA repair enzyme. Testes of 20 bulls over 2 years old, slaughtered in a slaughterhouse, were used in the study. After spermatological evaluations, the semen obtained from the cauda epididymis was frozen in liquid nitrogen vapor according to the straw method and stored in liquid nitrogen (-196 °C). Testicular tissue pieces obtained from the testicles were frozen by the slow freezing method in cryotubes in diluents containing Dimethylsulfoxide (DMSO) and Ethylene Glycol (EG) cryoprotectants and stored in liquid nitrogen (-196 °C). The total motility (TM) (85.89 ± 12.83 %), progressive motility (PM) (54.02 ± 15.77 %), and kinematic parameter values of fresh sperm were significantly higher compared to the TM (57.62 ± 13.13 %), PM (29.60 ± 10.76 %), and kinematic parameter values after thawing (P < 0.05). Significant decreases in plasma membrane integrity (PMI) and viability and an increase in chromatin condensation and morphological disorders in the head, middle part, and tail regions were observed in post-thaw semen samples (P < 0.05). When the effects of DMSO and EG on cell viability after thaw in frozen testicular tissue were evaluated, it was observed that the cell viability values of testicular tissues frozen with EG (45.70 ± 10.00) were statistically significantly lower than those frozen with DMSO (51.20 ± 7.70) (P < 0.05). When the effects of both cryoprotectants on gene expression in tissue and semen samples were examined, it was determined that gene expression increased on average 0.19 ± 0.27 times in the tissue samples in the DMSO group compared to fresh tissue samples and 0.17 ± 0.19 times in the tissue samples in the EG group. It was determined that gene expression levels increased by an average of 1.20 ± 1.08 times in post-thaw epididymal spermatozoa samples compared to fresh semen samples. The results show that cryopreservation can activate cellular repair mechanisms by stimulating PARP-1 gene expression and affect gene expression by activating specific pathways in tissues and cells.

Virus-like Particles as Antiviral Vaccine: Mechanism, Design, and Application

Virus-like particles (VLPs) are viral structural protein that are noninfectious as they do not contain viral genetic materials. They are safe and effective immune stimulators and play important roles in vaccine development because of their intrinsic immunogenicity to induce cellular and humoral immune responses. In the design of antiviral vaccine, VLPs based vaccines are appealing multifunctional candidates with the advantages such as self-assembling nanoscaled structures, repetitive surface epitopes, ease of genetic and chemical modifications, versatility as antigen presenting platforms, intrinsic immunogenicity, higher safety profile in comparison with live-attenuated vaccines and inactivated vaccines. In this review, we discuss the mechanism of VLPs vaccine inducing cellular and humoral immune responses. We outline the impact of size, shape, surface charge, antigen presentation, genetic and chemical modification, and expression systems when constructing effective VLPs based vaccines. Recent applications of antiviral VLPs vaccines and their clinical trials are summarized.

The Effects of Different Doses of ROCK Inhibitor, Antifreeze Protein III, and Boron Added to Semen Extender on Semen Freezeability of Ankara Bucks

In the presented study, the effects of ROCK inhibitor Y-27632, antifreeze protein III, and boron at two different doses were investigated on the spermatological parameters of Ankara buck semen after freeze−thawing. Ejaculates were collected from bucks using an electroejaculator during the breeding season. The ejaculates that showed appropriate characteristics were pooled and used in the dilution and freezing of semen. The extender groups were formed by adding two different doses of three different additives (ROCK inhibitor Y-27632, 5 and 20 µM; antifreeze protein III, 1 and 4 µg/mL; boron, 0.25 and 1 mM) to the control extender. The semen was diluted with the different extenders at 35−37 °C and loaded into straws. Sperm samples frozen in liquid nitrogen vapors, following equilibration, were stored in liquid nitrogen. It was observed that extender supplementation improved post-thaw motility of Ankara buck semen after freeze−thawing. Differences were significant (p < 0.01) for 5 and 10 µM doses of ROCK inhibitor (71.82% and 74.04 % motility), as well as for 0.25 and 1 mM doses of boron (76.36% and 72.08% motility), compared to the control group (66.15% motility). With respect to the evaluation of acrosomal integrity and mitochondrial activity after freeze−thawing, although supplementation provided protection at all doses, the efficacy was not statistically significant (p > 0.05). It was observed that DNA damage was improved by antifreeze protein III at 1 µg/mL (1.23% ± 0.23%) and by boron at all doses (0.25 mM: 1.83% and 1 mM: 1.18%) compared to the control group (3.37%) (p < 0.01), following the thawing process. In the present study, it was determined that some additives added to the extender provided significant improvements in buck spermatozoa motility and DNA damage after thawing.

Circumventing Drug Treatment? Intrinsic Lethal Effects of Polyethyleneimine (PEI)-Functionalized Nanoparticles on Glioblastoma Cells Cultured in Stem Cell Conditions

Simple Summary

Glioblastoma (GB) is the most frequent brain cancer that is highly difficult to treat. As with many cancer types, associated cancer stem cells can act as a reservoir of cancer-initiating cells, constituting a major hurdle for successful therapy. Herein, we report on a discovery of the intrinsic capability of polyethyleneimine-functionalized nanoparticles (PEI-NPs) to selectively eradicate glioblastoma stem cells (GSCs), contrary to current drug-based approaches to target and successfully eradicate GB. Already at negligible doses, PEI-NPs, without any anticancer therapeutic, very potently killed multiple GSC lines but not GB cells without stem cell characteristics. Moreover, PEI-NPs was observed in tumors in mice after both intravenous and intranasal administration, where the latter constitute a non-invasive administration route for drug delivery to the brain. These results, in turn, suggest that PEI-NPs can successfully cross the blood-brain barrier for the eradication of GSCs even without any anticancer drug, whereas the same NP platform can also be used for drug delivery thus opening up potential to reach synergistic therapeutic effects. This highly surprising intrinsic effect of the NP system on both the mechanistic action and specificity of GSC eradication puts forward a promising novel aspect of nanoparticles in medicine.

Abstract

Glioblastoma (GB) is the most frequent malignant tumor originating from the central nervous system. Despite breakthroughs in treatment modalities for other cancer types, GB remains largely irremediable due to the high degree of intratumoral heterogeneity, infiltrative growth, and intrinsic resistance towards multiple treatments. A sub-population of GB cells, glioblastoma stem cells (GSCs), act as a reservoir of cancer-initiating cells and consequently, constitute a significant challenge for successful therapy. In this study, we discovered that PEI surface-functionalized mesoporous silica nanoparticles (PEI-MSNs), without any anti-cancer drug, very potently kill multiple GSC lines cultured in stem cell conditions. Very importantly, PEI-MSNs did not affect the survival of established GB cells, nor other types of cancer cells cultured in serum-containing medium, even at 25 times higher doses. PEI-MSNs did not induce any signs of apoptosis or autophagy. Instead, as a potential explanation for their lethality under stem cell culture conditions, we demonstrate that the internalized PEI-MSNs accumulated inside lysosomes, subsequently causing a rupture of the lysosomal membranes. We also demonstrate blood–brain-barrier (BBB) permeability of the PEI-MSNs in vitro and in vivo. Taking together the recent indications for the vulnerability of GSCs for lysosomal targeting and the lethality of the PEI-MSNs on GSCs cultured under stem cell culture conditions, the results enforce in vivo testing of the therapeutic impact of PEI-functionalized nanoparticles in faithful preclinical GB models.

High-intensity interval training modulates male factor infertility through anti-inflammatory and antioxidative mechanisms in infertile men: A randomized controlled trial

The effects of 24 weeks of high-intensity interval training (HIIT) on markers of male reproductive function in infertile patients were studied. Infertile men (n = 441) were randomized to exercise (EX, n = 221) or non-exercise (NON-EX, n = 220) group. Patients in the EX group performed an interval training (1:1 work:rest ratio) 3 times per week at 75-95% of maximal oxygen consumption, for 24 weeks (VO_2max). Markers of inflammation and oxidative stress in the seminal plasma, as well as semen parameters, sperm DNA fragmentation and rates of pregnancy, were measured at baseline, on weeks 12, 24; and 7 and 30 days thereafter during the recovery period. The intervention resulted in decreased seminal levels of proinflammatory cytokines (IL-1β, IL-6, IL-8, and TNF-α) and markers of oxidative stress (ROS, MDA, and 8-isoprostane) (P < 0.05). The concentrations of seminal antioxidants were unaltered with HIIT intervention. These changes further coincide with promising developments in semen parameters, sperm DNA integrity and rates of pregnancy (P < 0.05). This may indicate that HIIT induced beneficial effects on markers of male reproductive function through decreased oxidative damage and proinflammatory status. Findings highlight the possibility that HIIT may be an effective intervention for male factor infertility and support the need for further human studies.

Effects of Aerobic, Resistance, and Combined Exercise on Markers of Male Reproduction in Healthy Human Subjects: A Randomized Controlled Trial

Hajizadeh Maleki, B, Tartibian, B, and Chehrazi, M. Effects of aerobic, resistance, and combined exercise on markers of male reproduction in healthy human subjects: a randomized controlled trial. J Strength Cond Res 33(4): 1130-1145, 2019-The effects of moderate intensity treadmill exercise training (MI), resistance training (RT), and combined treadmill + resistance training (CT) on markers of male reproductive function including seminal markers of oxidative stress and inflammation, and semen quality and sperm DNA integrity were evaluated in healthy human subjects. A total of 376 healthy sedentary male volunteers (aged 25-40) were screened and 282 were randomized into 4 treatment groups: MI (n = 71), RT (n = 71), CT (n = 71), and nonexercise (NON-EX, n = 70) groups for an experimental period of 24 weeks. After the intervention, compared with the NON-EX group, all 3 MI, RT, and CT exercise modalities showed significantly reduced body mass, fat percent, waist circumference, reactive oxygen species, interleukin (IL)-1β, IL-6, IL-8 and tumor necrosis factor-α and improved maximal oxygen uptake (V[Combining Dot Above]O2max), progressive motility, sperm morphology, sperm concentration and sperm DNA integrity, as indicated by a decrease of percentage of terminal deoxynucleotidyl transferase-mediated fluorescein-dUTP nick end labeling-positive sperm cells (p ≤ 0.05). Body mass index, semen volume, number of spermatozoa, superoxide dismutase, catalase, total antioxidant capacity, malondialdehyde, and 8-isoprostane improved significantly in the MI and CT groups (p ≤ 0.05) but not significantly in the RT group (p > 0.05). In summary, all 3 MI, RT, and CT interventions attenuate seminal markers of inflammation and oxidative stress and improve body composition, semen quality parameters, and sperm DNA integrity in the studied population. In respect to all the aspects studied, those men who took part in MI intervention had the best results. Considering the seminological parameters, however, CT had a synergistic effect and was superior over the other interventions used.

Combined aerobic and resistance exercise training for improving reproductive function in infertile men: a randomized controlled trial

This randomized controlled trial was conducted to examine the effects of 24 weeks of combined aerobic and resistance exercise training on seminal markers of inflammation and oxidative stress as well as markers of male reproductive function and reproductive performance in infertile patients. Of a total of 1296 infertile patients (aged 25–40 years) who were screened, 556 were randomly assigned to exercise (n = 278) and nonexercise (n = 278) groups. Semen samples were taken before and at 12 and 24 weeks as well as 7 and 30 days post-intervention. The training program reduced seminal proinflammatory cytokines (interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor alpha) and markers of oxidative stress (reactive oxygen species, malondialdehyde, and 8-isoprostane) (P < 0.05). Additional improvements were also achieved in seminal antioxidant defense system (superoxide dismutase, catalase, and total antioxidant capacity) (P < 0.05). Training-induced changes in inflammation and oxidative stress status correlated with favorable improvements in semen parameters, sperm DNA integrity, and pregnancy rate (P < 0.05). In conclusion, these results support the evidence for the favorable effects of combined aerobic and resistance exercise training in male factor infertility.

Moderate aerobic exercise training for improving reproductive function in infertile patients: A randomized controlled trial

This study investigated for the first time the changes in seminal markers of inflammation, oxidative stress status, semen parameters, sperm DNA integrity as well as pregnancy rate following 24weeks of moderate aerobic exercise in infertile patients. A total of 1026 sedentary men (aged 25-40years) attending the infertility clinic with history of more than one year of infertility, were screened and 419 were randomized to either exercise (EX, n=210) or non-exercise (NON-EX, n=209) groups. Exercise training favorably attenuated seminal markers of both inflammation (IL-1β, IL-6, IL-8, and TNF-α) and oxidative stress (ROS, MDA, 8-Isoprostane) as well as enhanced antioxidant defense system (SOD, catalase and TAC) (P<0.05). These changes correlate with favorable improvements in semen parameters, sperm DNA integrity and pregnancy rate (P<0.05). The results provide information about the effectiveness of moderate aerobic exercise training as a treatment option for male factor infertility. The 4-week detraining period was not enough to reverse all benefits promoted by exercise intervention.

The effects of three different exercise modalities on markers of male reproduction in healthy subjects: a randomized controlled trial

The aim of this study was to investigate the effects of moderate-intensity continuous training (MICT), high-intensity continuous training (HICT) and high-intensity interval training (HIIT) on markers of male reproduction including seminal markers of oxidative stress and inflammation as well as semen quality and sperm DNA integrity in healthy human subjects. A total of 397 healthy male volunteers were screened and 280 were randomly assigned to one of the MICT (n = 70), HICT (n = 70), HIIT (n = 70) and non-exercise (NON-EX, n = 70) groups. Subjects had inflammatory markers (IL-1β, IL-6, IL-8 and TNF-α), oxidants (ROS, MDA and 8-isoprostane), antioxidants (SOD, catalase and TAC), semen parameters and sperm DNA damage measured at baseline (T1), the end of week 12 (T2), the end of week 24 (T3), and 7 (T4) and 30 days (T5) after training. Chronic MICT, HICT and HIIT attenuated seminal markers of oxidative stress and inflammation with different kinetics for the three types of exercise (P < 0.05), and these changes were correlated with favorable improvements in semen quality parameters and sperm DNA integrity (P < 0.05). MICT was superior to HICT and HIIT in the improvements of markers of male reproductive function (P < 0.05). In conclusion, different exercise modalities favorably affect markers of male reproduction with different kinetics, suggesting intensity-, duration- and type-dependent adaptations to exercise training in healthy human subjects.

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.

Profiling signaling proteins in human spermatozoa: biomarker identification for sperm quality evaluation

OBJECTIVE

To determine the correlation between semen basic parameters and the expression and activity of signaling proteins.

DESIGN

In vitro studies with human spermatozoa.

SETTING

Academic research institute.

PATIENT(S)

Thirty-seven men provided semen samples for routine analysis.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Basic semen parameters tracked included sperm DNA fragmentation (SDF), the expression levels of 75 protein kinases, and the phosphorylation/cleavage patterns of 18 signaling proteins in human spermatozoa.

RESULT(S)

The results indicated that the phosphorylated levels of several proteins (Bad, GSK-3β, HSP27, JNK/SAPK, mTOR, p38 MAPK, and p53), as well as cleavage of PARP (at D214) and Caspase-3 (at D175), were significantly correlated with motility parameters. Additionally, the percentage of morphologically normal spermatozoa demonstrated a significant positive correlation with the phosphorylated levels of p70 S6 kinase and, in turn, head defects and the teratozoospermia index (TZI) showed a significant negative correlation with the phosphorylated levels of Stat3. There was a significant positive correlation between SDF and the teratozoospermia index, as well as the presence of head defects. In contrast, SDF negatively correlated with the percentage of morphologically normal spermatozoa and the phosphorylation of Akt and p70 S6 kinase. Subjects with varicocele demonstrated a significant negative correlation between head morphological defects and the phosphorylated levels of Akt, GSK3β, p38 MAPK, and Stat1. Additionally, 34 protein kinases were identified as expressed in their total protein levels in normozoospermic samples.

CONCLUSION(S)

This study contributed toward establishing a biomarker "fingerprint" to assess sperm quality on the basis of molecular parameters.

Cleaved PARP-1, an Apoptotic Marker, can be Detected in Ram Spermatozoa

The presence of apoptotic features in spermatozoa has been related to lower quality and functional impairment. Members of the poly-ADP-ribose polymerases (PARP) familyare involved in both DNA repair and apoptosis, playing important roles in spermatogenesis. Poly-ADP-ribose polymerase can be cleaved by caspases, and the presence of its cleavage product (cPARP) in spermatozoa has been related to chromatin remodelling during spermatogenesis and to the activation of apoptotic pathways. There are no reports on immunodetection of cPARP in ram spermatozoa; thus, we have tested a commercially available antibody for this purpose. cPARP was microscopically detected in the acrosomal ridge of some spermatozoa (indirect immunofluorescence). A preliminary study was carried out by flow cytometry (direct immunofluorescence, FITC). Ram semen was extended in TALP and incubated for 4 h with apoptosis inducers staurosporine (10 μm) or betulinic acid (200 μm). Both inducers and incubation caused a significant increase in cPARP spermatozoa (0 h, control: 21.4±3.3%, inducers: 44.3±1.4%; 4 h, control: 44.3±2.4%, inducers: 53.3±1.4%). In a second experiment, we compared the sperm fractions after density gradient separation (pellet and interface). The pellet yielded a slightly lower proportion of cPARP spermatozoa (28.5±1.2% vs 36.2±2.0% in the interface; p < 0.001), and a 12-h incubation increased cPARP similarly in both fractions (p < 0.001). cPARP seems to be an early marker of apoptosis in ram semen, although its presence in untreated samples was weakly related to worse quality (pellet/interface). We suggest to study the relationship of PARP and cPARP levels with between-male differences on sperm fertility.

Investigation on the Origin of Sperm DNA Fragmentation: Role of Apoptosis, Immaturity and Oxidative Stress

Sperm DNA fragmentation (sDF) represents a threat to male fertility, human reproduction and the health of the offspring. The causes of sDF are still unclear, even if apoptosis, oxidative assault and defects in chromatin maturation are hypothesized. Using multicolor flow cytometry and sperm sorting, we challenged the three hypothesized mechanisms by simultaneously evaluating sDF and signs of oxidative damage (8-hydroxy, 2'-deoxyguanosine [8-OHdG] and malondialdehyde [MDA]), apoptosis (caspase activity and cleaved poly[ADP-ribose] polymerase [cPARP]) and sperm immaturity (creatine phosphokinase [CK] and excess of residual histones). Active caspases and c-PARP were concomitant with sDF in a high percentage of spermatozoa (82.6% ± 9.1% and 53.5% ± 16.4%, respectively). Excess of residual histones was significantly higher in DNA-fragmented sperm versus sperm without DNA fragmentation (74.8% ± 17.5% and 37.3% ± 16.6%, respectively, p < 0.005), and largely concomitant with active caspases. Conversely, oxidative damage was scarcely concomitant with sDF in the total sperm population, at variance with live sperm, where 8-OHdG and MDA were clearly associated to sDF. In addition, most live cells with active caspase also showed 8-OHdG, suggesting activation of apoptotic pathways in oxidative-injured live cells. This is the first investigation on the origin of sDF directly evaluating the simultaneous presence of the signs of the hypothesized mechanisms with DNA breaks at the single cell level. The results indicate that the main pathway leading to sperm DNA breaks is a process of apoptosis, likely triggered by an impairment of chromatin maturation in the testis and by oxidative stress during the transit in the male genital tract. These findings are highly relevant for clinical studies on the effects of drugs on sDF and oxidative stress in infertile men and for the development of new therapeutic strategies.

Role of poly(ADP-ribose) polymerases in male reproduction

Poly(ADP-ribose) polymerases (PARPs) are a family of enzymes involved in a wide variety of biological processes, including DNA repair and maintenance of genomic stability following genotoxic stress, and regulates the expression of various proteins at the transcriptional level as well as replication and differentiation. However, excessive activation of PARP has been shown to contribute to the pathogenesis of several diseases associated with oxidative stress (OS), which has been known to play a fundamental role in the etiology of male infertility. Based on the degree and type of the stress stimulus, PARP directs cells to specific fates (such as, DNA repair vs. cell death). A large volume of accumulated evidence indicates the presence of PARP and its homologs in testicular germ line cells and its activity may offer a key mechanism for keeping DNA integrity in spermatogenesis. On the other hand, a possible role of PARP overactivation in OS-induced male reproductive disorders and in human sperm is gaining significance in recent years. In this review, we focus on the findings about the importance of PARP-1 and PARP-2 in male reproduction and possible involvement of PARP overactivation in various clinical conditions associated with male infertility.

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.

Novel technologies for selecting the best sperm for in vitro fertilization and intracytoplasmic sperm injection

The increasing focus on developing new tools to more accurately diagnose and select individual sperm before intracytoplasmic sperm injection will allow us to counsel and treat couples with greater confidence and efficiency. Current sperm selection techniques are based on the premise that if an ejaculated spermatozoon has cleared spermatogenesis with the correct morphology and/or membrane properties then it is most likely normal. Techniques that are designed to prepare a clean "normal" sperm population or that assist in selecting an individual "normal" spermatozoon are currently being investigated. The use of techniques, including density-gradient preparation, electrophoretic separation, microfluidics, high-magnification sperm morphology selection, and hyaluronic acid binding, is discussed. The research evidence that supports the interrelated developmental and genetic integrity of the selected sperm, particularly sperm DNA damage and clinical outcome evidence are presented.

Treatment of human sperm with serine protease during density gradient centrifugation

PURPOSE

Seminal pathogens can bind specifically or non-specifically to spermatozoa, rendering semen decontamination procedures ineffective, whereby vertical or horizontal transmission of the infection could occur. Serine proteases have been demonstrated to effectively inactivate viruses and to break pathogen-sperm bonds. However, the addition of a protease to density gradient layers during semen processing could negatively impact on sperm parameters. This study investigated the effect of the addition of a recombinant, human-sequence protease (rhProtease) on sperm parameters during density gradient centrifugation.

METHODS

(i) Pooled semen samples (n = 9) were split and processed by density gradient centrifugation, with the top density layers supplemented, or non-supplemented with rhProtease at three different concentrations (diluted 2, 10 and 20 times). Sperm parameters were then analysed by flow cytometry and computer-assisted semen analyses. (ii) Semen samples (n = 5) were split and similarly processed using PureSperm® Pro, with rhProtease in the 40 % density gradient layer, or standard PureSperm® not supplemented with rhProtease (Nidacon, International) respectively. The Hemizona assay was then utilized to compare sperm-zona binding post processing.

RESULTS

Evaluation of sperm parameters indicated that rhProtease did not, at any of the tested concentrations, have an impact on (i) mitochondrial membrane potential, vitality, motility, or (ii) zona binding potential.

CONCLUSION

We report that the addition of rhProtease to density gradients is a non-detrimental approach that could improve the effectiveness of semen processing for the elimination of seminal pathogens, and benefit assisted reproduction outcome.

Correlation between seminal oxidative stress biomarkers and antioxidants with sperm DNA damage in elite athletes and recreationally active men

OBJECTIVE

To evaluate the seminal plasma 8-isoprostane, reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), catalase, total antioxidant capacity (TAC), and levels of sperm DNA fragmentation in elite athletes and recreationally active men.

DESIGN

Prospective design was used for this study.

SETTING

The study was performed in the Exercise Physiology Laboratory of the Urmia University.

PARTICIPANTS

Fifty-six elite athletes and 52 recreationally active men (18-28 years) participated in this study.

INTERVENTION

All subjects had a semen sampling at baseline.

MAIN OUTCOME MEASURES

Total antioxidant capacity and SOD activity were measured by colorimetric assay. Levels of ROS were measured by a chemiluminescence assay. Malondialdehyde levels were measured by thiobarbituric acid reactive substance assay. Catalase activity was measured by monitoring the initial rate of disappearance of hydrogen peroxide. Concentration of free 8-isoprostane was measured by enzyme immunoassay method. Sperm DNA fragmentation was evaluated with the terminal deoxynucleotidyl transferase-mediated fluorescein dUTP nick end-labeling assay.

RESULTS

Recreationally active men have significantly higher levels of body fat, seminal SOD, TAC, and catalase and lower levels of V[Combining Dot Above]O2max, seminal ROS, MDA, and 8-isoprostane and subsequently lower rate of sperm DNA fragmentation when compared with elite athletes (P < 0.001). Significantly negative correlation was observed between sperm DNA fragmentation with body fat, seminal SOD, catalase, and TAC levels (P < 0.001). Significantly positive correlation was observed between sperm DNA fragmentation with V[Combining Dot Above]O2max, seminal 8-isoprostane, ROS, and MDA levels (P < 0.001).

CONCLUSION

Spermatozoa from recreationally active men may be less susceptible to oxidative stress-induced DNA damage and hence infertility.

Association of sperm morphology and the sperm deformity index (SDI) with poly (ADP-ribose) polymerase (PARP) cleavage inhibition

Apoptosis was induced in immature and mature sperm in the presence or absence of poly (ADP-ribose) polymerase (PARP) inhibitor. The association of cleaved (cPARP) with sperm morphology was examined using sperm deformity index (SDI) score. The SDI scores are associated with PARP cleavage as an early marker of apoptosis.

TUNEL as a test for sperm DNA damage in the evaluation of male infertility

OBJECTIVES

To standardize the TUNEL assay by establishing inter- and intraobserver variability, interassay variability, cutoff values, sensitivity and specificity of the assay, and studying the distribution of the DNA damage in a population of infertile men referred to a clinical andrology laboratory.

METHODS

Seminal ejaculates from 25 healthy male volunteers (controls) and 194 infertile men (with male factor infertility) referred to an andrology laboratory were examined for DNA damage by TUNEL assay using flow cytometric analysis.

RESULTS

Both the inter- and intraobserver variability and interassay variability was small (<10%). DNA damage in the controls was 11.9 ± 6.8% vs. 29.5 ± 18.7% in patients (P <.001). The cut-off value of 19.25% maximized the observed sensitivity (64.9%) and specificity (100%) of the assay. The distribution of DNA damage in the patients was as follows: 14.9% (29 of 194) with DNA damage between 0% and 10%; 22.7% (44 of 194) between 10% and 20%; 8.8% (17 of 194) between 20% and 30%; and 17.5% (34 of 194) between 30% and 40%. Finally, 27.3% (53 of 194) had TUNEL values >40%.

CONCLUSIONS

We report a detailed standardization of the TUNEL assay for clinical use, as well as reference ranges for DNA damage in normal healthy donors and infertile men. A cut-off of 19.25% with observed 100% specificity established in our program can differentiate infertile men with DNA damage from healthy men. This test can be offered to infertile patients who are idiopathic, have severe oxidative stress-related abnormal semen quality, and contribute to the infertility problem of the couple who are considering assisted reproductive techniques.

Implication of apoptosis in sperm cryoinjury

Apoptosis is an ongoing physiological phenomenon that has been documented to play a role in male infertility, if deregulated. Caspase activation, externalization of phosphatidylserine, alteration of mitochondrial membrane potential and DNA fragmentation are markers of apoptosis found in ejaculated human spermatozoa. These markers appear in excess in subfertile men and functionally incompetent spermatozoa. Sperm cryopreservation is a widely used procedure in the context of assisted reproductive techniques. Cryopreservation and thawing is a procedure that inflicts irreversible injury on human spermatozoa. The damage is manifested by a decrease in recovery of viable spermatozoa with optimum fertilization potential. This review describes the implication of apoptosis as one of the possible mechanisms involved in sperm cryoinjury. Evidence shows significant increase in some apoptosis markers following cryopreservation and thawing. On the other hand, the increase in sperm DNA fragmentation following cryopreservation and thawing requires further investigation. Specific technical measures should be applied to minimize the induction of apoptosis in human spermatozoa during cryopreservation and thawing. These include standardization of freezing protocols and cryoprotectant use. Selection of non-apoptotic spermatozoa may also prove to be of benefit.

Potential biological role of poly (ADP-ribose) polymerase (PARP) in male gametes

Maintaining the integrity of sperm DNA is vital to reproduction and male fertility. Sperm contain a number of molecules and pathways for the repair of base excision, base mismatches and DNA strand breaks. The presence of Poly (ADP-ribose) polymerase (PARP), a DNA repair enzyme, and its homologues has recently been shown in male germ cells, specifically during stage VII of spermatogenesis. High PARP expression has been reported in mature spermatozoa and in proven fertile men. Whenever there are strand breaks in sperm DNA due to oxidative stress, chromatin remodeling or cell death, PARP is activated. However, the cleavage of PARP by caspase-3 inactivates it and inhibits PARP's DNA-repairing abilities. Therefore, cleaved PARP (cPARP) may be considered a marker of apoptosis. The presence of higher levels of cPARP in sperm of infertile men adds a new proof for the correlation between apoptosis and male infertility. This review describes the possible biological significance of PARP in mammalian cells with the focus on male reproduction. The review elaborates on the role played by PARP during spermatogenesis, sperm maturation in ejaculated spermatozoa and the potential role of PARP as new marker of sperm damage. PARP could provide new strategies to preserve fertility in cancer patients subjected to genotoxic stresses and may be a key to better male reproductive health.

Markers of oxidative stress and sperm chromatin integrity

Oxidative stress (OS) is an imbalance between the amount of reactive oxygen species (ROS) produced and the ability of the antioxidants to scavenge these. OS has been established as a major etiological cause of male infertility. High levels of ROS are harmful and cause damage to sperm nuclear DNA. Evaluation of OS-related damage to spermatozoa is therefore highly relevant in assisted reproductive techniques (ART) such as intracytoplasmic sperm injection (ICSI). ICSI is an effective therapy for severe male factor infertility that bypasses the majority of reproductive tract deficiencies. Despite the controversial findings in the existing literature, there is now enough evidence to show that sperm DNA damage is detrimental to reproductive outcomes. In addition to impairment of fertility, such damage might increase the transmission of genetic diseases to the offspring. Standardization of protocols to assess ROS, antioxidant status, and DNA damage is very important for implementation of these tests in clinical practice. Estimation of seminal ROS levels and extent of sperm DNA damage, especially in an infertile male, may help develop new therapeutic strategies and improve the success of ART.