Sperm maturity and treatment choice of in vitro fertilization (IVF) or intracytoplasmic sperm injection: diminished sperm HspA2 chaperone levels predict IVF failure

Pfaffia glomerata polyploid accession compromises male fertility and fetal development

ETHNOPHARMACOLOGICAL RELEVANCE

Pfaffia glomerata (Spreng.) Pedersen has traditionally been used as a tonic and a stimulant by the Brazilian population. It shows higher biomass accumulation and production of secondary compounds, such as the phytosterol 20-hydroxyecdysone.

AIMS

The present study aimed to evaluate the effects of the hydroalcoholic extract of the root of tetraploid P. glomerata (BGEt) on testicular parenchyma, and its implications on fertility.

MATERIAL AND METHODS

Adult Swiss mice were divided as: control (water) and sildenafil citrate (7 mg/kg), BGEt at 100, 200, and 400 mg/kg, and BGEtD 200 mg/kg (treated with BGE every three days). Males (n = 4/group) were mated with normal untreated adult females to assess fertility rates, while other animals (n = 6/group) were euthanized for testis, epididymis, and oxidative stress analyses.

RESULTS

Increase in tubule diameter and epithelium height in the discontinuous group, in addition to an increase in the proportion of tubules with moderate pathologies was observed. The pre-implantation loss was lower in all treated groups. The post-implantation loss was significantly increased in all treated groups, except for the lowest BGEt dose. BGEt intake caused a decrease in daily sperm production, along with the number and quality of sperm in the epididymis. Changes were observed in protein carbonylation and hydrogen peroxide and nitric oxide levels, characterizing oxidative stress.

CONCLUSIONS

The hydroalcoholic extract of P. glomerata tetraploid altered sperm and testicular parameters, compromising embryonic development after implantation.

Quantitative proteomics of sperm tail in asthenozoospermic patients: exploring the molecular pathways affecting sperm motility

Asthenozoospermia, characterized by low sperm motility, is one of the most common causes of male infertility. While many intrinsic and extrinsic factors are involved in the etiology of asthenozoospermia, the molecular basis of this condition remains unclear. Since sperm motility results from a complex flagellar structure, an in-depth proteomic analysis of the sperm tail can uncover mechanisms underlying asthenozoospermia. This study quantified the proteomic profile of 40 asthenozoospermic sperm tails and 40 controls using TMT-LC-MS/MS. Overall, 2140 proteins were identified and quantified where 156 proteins have not been described earlier in sperm tail. There were 409 differentially expressed proteins (250 upregulated and 159 downregulated) in asthenozoospermia which by far is the highest number reported earlier. Further, bioinformatics analysis revealed several biological processes, including mitochondrial-related energy production, oxidative phosphorylation (OXPHOS), citric acid cycle (CAC), cytoskeleton, stress response, and protein metabolism altered in asthenozoospermic sperm tail samples. Collectively, our findings reveal the importance of mitochondrial energy production and induced stress response as potential mechanisms involved in the loss of sperm motility in asthenozoospermia.

The role of spermatozoa-zona pellucida interaction in selecting fertilization-competent spermatozoa in humans

Human fertilization begins when a capacitated spermatozoon binds to the zona pellucida (ZP) surrounding a mature oocyte. Defective spermatozoa-ZP interaction contributes to male infertility and is a leading cause of reduced fertilization rates in assisted reproduction treatments (ARTs). Human ejaculate contains millions of spermatozoa with varying degrees of fertilization potential and genetic quality, of which only thousands of motile spermatozoa can bind to the ZP at the fertilization site. This observation suggests that human ZP selectively interacts with competitively superior spermatozoa characterized by high fertilizing capability and genetic integrity. However, direct evidence for ZP-mediated sperm selection process is lacking. This study aims to demonstrate that spermatozoa-ZP interaction represents a crucial step in selecting fertilization-competent spermatozoa in humans. ZP-bound and unbound spermatozoa were respectively collected by a spermatozoa-ZP coincubation assay. The time-course data demonstrated that ZP interacted with a small proportion of motile spermatozoa. Heat shock 70 kDa protein 2 (HSPA2) and sperm acrosome associated 3 (SPACA 3) are two protein markers associated with the sperm ZP-binding ability. Immunofluorescent staining indicated that the ZP-bound spermatozoa had significantly higher expression levels of HSPA2 and SPACA3 than the unbound spermatozoa. ZP-bound spermatozoa had a significantly higher level of normal morphology, DNA integrity, chromatin integrity, protamination and global methylation when compared to the unbound spermatozoa. The results validated the possibility of applying spermatozoa-ZP interaction to select fertilization-competent spermatozoa in ART. This highly selective interaction might also provide diagnostic information regarding the fertilization potential and genetic qualities of spermatozoa independent of those derived from the standard semen analysis.

Paternal factors in recurrent pregnancy loss: an insight through analysis of non-synonymous single-nucleotide polymorphism in human testis-specific chaperone HSPA2 gene

Heat shock protein A2 (HSPA2) is a testis-specific molecular chaperone of the 70 kDa heat shock protein (HSP70) family and reported to play a key role in spermatogenesis as well as in the remodelling of the sperm surface during capacitation. It is established that mice lacking HSPA2 gene are infertile and spermatozoa that fail to interact with the zona pellucida of the oocyte consistently lack HSPA2 protein expression. However, its role in post fertilization events is not fully understood. Owing to the importance of HSPA2 in male reproduction, the present study is undertaken to reveal the association between genetic mutation and phenotypic variation in recurrent pregnancy loss (RPL) patients through an in silico prediction analysis. In this study, we used different computational tools and servers such as SIFT, PolyPhen2, PROVEAN, nsSNPAnalyzer, and SNPs & GO to analyse the functional consequences of the nsSNPs in human HSPA2 gene. The most damaging amino acid variants generated were subjected to I-Mutant 2.0 and ConSurf. Post-translational modifications such as phosphorylation mediated by these deleterious nsSNPs were analysed using NetPhos 2.0, and gene-gene interaction study was conducted using GeneMANIA. Finally, in-depth studies of the nsSNPs were studied through Project HOPE. The findings of the study revealed 18 nsSNPs to be deleterious using a combinatorial bioinformatic approach. Further functional analysis suggests that screening of nsSNP variants of HSPA2 that tend to be conserved and has potential to undergo phosphorylation at critical positions (rs764410231, rs200951589, rs756852956) may be useful for predicting outcome in altered reproductive outcome. The physicochemical alterations and its impact on the structural and functional conformity were determined by Project HOPE. Gene-gene interaction depicts its close association with antioxidant enzyme (SOD1) strongly supporting an inefficient oxidative scavenging regulatory mechanism in the spermatozoa of RPL patients as reported earlier. The present study has thus identified high-risk deleterious nsSNPs of HSPA2 gene and would be beneficial in the diagnosis and prognosis of the paternal effects in RPL patients.

Evaluation of seminal plasma HSPA2 protein as a biomarker of human spermatogenesis status

In mammals, testicular Heat shock-related 70 kDa protein 2 (HSPA2) is a chaperon strictly linked to spermatogenesis status, whereas its presence in spermatozoa ensures successful oocyte fertilization. However, there is little information on this protein in seminal plasma in infertile males. Based on our previous two independent studies, we have selected HSPA2 to evaluate this seminal plasma protein is a potential biomarker of correct spermatogenesis. Using immunoblotting and mass spectrometry (MS) we have screened human seminal plasma samples for the presence of HSPA2. Samples were obtained from individuals with normozoospermia, cryptozoospermia, non-obstructive and obstructive azoospermia. Our results showed a lack of HSPA2 in seminal plasma in all azoospermic males however, in cryptozoospermia the results were extremely diversified. Additionally, the application of 2-dimensional gel electrophoresis (2-DE) indicated the presence of additional protein isoforms suggesting possible mechanisms underlying the male infertility. Our findings suggest seminal plasma HSPA2 protein as a possible biomarker not only of spermatogenesis status, especially in cryptozoospermic males, but also as a biomarker predicting the success of reproductive treatment including assisted reproductive techniques (ART).

Sperm Selection Technology in ART

Intracytoplasmic sperm injection (ICSI) is a commonly used in vitro fertilization technique. Selection of sperm for injection is currently done using subjective assessment of morphology, which may not accurately identify the best-quality sperm. Hyaluronic acid receptors on sperm plasma membranes are a marker of maturity, and sperms which are capable of binding immobilized hyaluronic acid in vitro are of higher quality. This can be used as an advanced sperm selection technique to choose sperm for ICSI, termed physiological ICSI (PICSI). Several studies reported improved fertility treatment outcomes when using PICSI compared with conventional ICSI; however, the majority of studies are underpowered. Recently, a large, multicenter, randomized controlled trial, known as the Hyaluronic Acid Binding Sperm Selection (HABSelect) trial, found a significant reduction in miscarriage rates with PICSI, but no significant effect on live birth rate. There are still many avenues through which PICSI may provide an advantage, subject to confirmation by future research, such as improved long-term health of offspring. Other advanced sperm selection techniques include intracytoplasmic morphologically selected sperm injection, magnetic-activated cell sorting, and Zeta potential sperm selection; however, the most recent Cochrane review concluded that there is currently insufficient evidence to ascertain whether these techniques improve clinical outcomes, such as live birth rates.

Association of heat shock protein A2 expression and sperm quality after N-acetyl-cysteine supplementation in astheno-terato-zoospermic infertile men

In infertile men, reduced expression of heat shock protein A2 (HSPA2) is related to reduced sperm quality and function. The present study has aimed to investigate the effects of N-acetyl-cysteine (NAC) supplementation on expression of heat shock protein A2 (HSPA2). In this study in continuation of previous study, semen samples from 50 astheno-terato-zoospermic men who have received NAC (600 mg/day) orally for three months were evaluated for expression HSPA2 using RT-PCR, and Western blot analysis. In addition, semen samples of these individuals were assessed for sperm parameters, DNA fragmentation (TUNEL), protamine deficiency (CMA3), lipid peroxidation index (MDA) and total antioxidant capacity (TCA). All assessment was carried out before and after NAC treatment. In addition to improved sperm parameters and aforementioned functional parameters, the presented results revealed the significant increase in relative expression levels of HSPA2 was obtained after using NAC treatment (p < .05). Correlation analysis also demonstrated that HSPA2 expression is significantly related to most of the assessed parameters. NAC may directly or indecently impose its beneficial effect through increased expression of HSPA2, which plays a potential role in proper folding of element needed to counteract stress condition in infertile individuals.

Human sperm chaperone HSPA2 distribution during in vitro capacitation

Human fertilization success depends on the ability of the spermatozoa to undergo capacitation. Even though this process can be conducted in vitro, the optimal time for a sperm cell to complete capacitation in vitro is still under discussion due to the lack of proper capacitation biomarkers. Here, we evaluated the influence of in vitro capacitation time on HSPA2 distribution over human sperm head testing this chaperone as a potential capacitation biomarker. The chaperone was assessed in human spermatozoa from 16 normozoospermic donors using indirect immunofluorescence in uncapacitated, one and four-hour capacitated spermatozoa. The percentage of HSPA2 immunofluorescent cells before and after one hour of capacitation did not differ significantly. However, after four hours of capacitation, we observed a significantly higher percentage of HSPA2 labelled cells. In fluorescent cells analysed before capacitation, we could not identify a predominant distribution pattern. Meanwhile, after capacitation, most sperm showed a highly labelled equatorial band accompanied by a homogeneous fluorescence throughout the acrosomal region. Our findings suggest that HSPA2 needs more than one hour of in vitro capacitation for being correctly distributed in the anterior region of the sperm head. In conclusion, the present study provides solid evidences for the utility of HSPA2 as a biomarker of human sperm in vitro capacitation. Due to its importance during egg-sperm recognition, the use of HSPA2 as a biomarker before an artificial reproduction technique may be suggested, in addition to a longer capacitation time during sperm preparation.

How bad is brazilian ginseng extract for reproductive parameters in mice?

Properties attributed to the Panax ginseng are also attributed to the Brazilian ginseng, such as adaptogenic and aphrodisiac effects. There are studies demonstrating that the Brazilian ginseng (BGE) possibly increases the serum levels of testosterone and nitric oxide in mice and rats. The present study aimed to evaluate the effects of its extract on male fertility and sperm quality. Male Swiss mice (n = 60) were divided into six groups. The control animals were provided 0.5 mL of water, and 0.5 mL of water containing 7 mg/kg per day (d) sildenafil citrate. Other animals were treated with BGE at 100 mg/kg/d, 200 mg/kg/d, and 400 mg/kg/d by gavage for 42 days. Finally, animals from the last group received 200 mg/kg BGE every 3 days (3-3d) by gavage for 42 days. The results showed a reduction in the number of resistant spermatids in the testis and damage to daily sperm production, culminating in a reduction in the number of epididymal spermatozoa. Although the sperm quality decreased in all experimental animals, only males treated with BGE 100 mg/kg/d showed pre and post implantation embryo losses. We concluded that BGE alters sperm viability compromising the embryonic development after implantation.

Impact of sperm characteristics on time-lapse embryo morphokinetic parameters and clinical outcome of conventional in vitro fertilization

BACKGROUND

Sperm abnormalities may negatively affect embryo development.

OBJECTIVES

To determine the influence of sperm abnormalities (morphology, motility, DNA fragmentation) on embryo morphokinetic variables and clinical outcome of conventional IVF.

MATERIALS AND METHODS

Participants were 86 couples undergoing in vitro fertilization (IVF). Sperm morphology was evaluated according to the strict criteria proposed by Kruger/Tygerberg. CASA system was applied for sperm motility assessment. Sperm DNA fragmentation was assessed by the chromatin structure assay (SCSA). Morphokinetic parameters were determined in 223 embryos obtained from conventional IVF only and cultured in a single-step medium using time-lapse imaging technology.

RESULTS

Time-lapse variables from the initial embryo development, such as time of pronuclei fading (tPNf) and time for two cells (t2), were those more strongly related with abnormalities of sperm motility, morphology, and DNA fragmentation. Sperm morphological abnormalities rather than sperm motility were more closely associated with embryo morphokinetics. Sperm head defects were mainly correlated with the last stages of embryonic development (t9 to tHB), sperm midpiece defects with intermediate cleaving embryos (t5-t9), and sperm tail defects with the initial stages of embryonic development (tPNa-t4). Excess residual cytoplasm was positively correlated with all embryo morphokinetic parameters except t2 and tM. Absence of acrosomes, pinheads, coiled tails, and multiple sperm morphological defects correlated negatively with time-lapse embryo morphokinetic variables.

DISCUSSION

A large number of sperm-related variables, including frequency of specific morphological defects, morphological indexes, DNA fragmentation and motility, and time-lapse embryo variables, such as time intervals based mainly of 15 time points were recorded.

CONCLUSION

There were strong associations between specific sperm defects of the head, midpiece, and tail with certain stages of embryonic development from observation of pronuclei to the hatched blastocyst. Coiled tail, cumulative head defects, and multiple abnormalities index (MAI) were associated both with embryo morphokinetics and the implantation success.

Effects of isolated or combined exposure to sibutramine and rosuvastatin on reproductive parameters of adult male rats

Many obese patients are exposed to hypolipidemic and serotonin-norepinephrine reuptake inhibitor (SNRI) drugs. Statins are one of the most marketed drugs in the world to treat dyslipidemia, while sibutramine, a SNRI drug, is prescribed in some countries to treat obesity and is detected as an additive in many adulterated weight loss supplements marketed worldwide. Previous studies reported adverse effects of isolated exposure to these drugs on male rat reproductive parameters. In the present work, we further investigated male reproductive toxicity of these drugs, administered in isolation or combination in adult rats for a longer period of treatment. Adult male rats (90 days) were treated (gavage) for 70 days with saline and dimethyl sulfoxide (control), sibutramine (10 mg/kg), rosuvastatin (5 mg/kg), or rosuvastatin combined with sibutramine. Sibutramine alone or with rosuvastatin, promoted a reduction in food intake and body weight gain, weight of the epididymis, ventral prostate and seminal vesicle; as well as decreased sperm reserves and transit time through the epididymis; androgen depletion; and increased index of cytoplasmic droplet. The rosuvastatin-treated group showed reduced frequency of ejaculation. Exposure to this drug alone or combined with sibutramine impaired epididymal morphology. Co-exposed rats had altered epididymal morphometry, and seminal vesicle and testis weights. The rats also showed decreased fertility after natural mating and a trend toward a delay in ejaculation, suggesting a small synergistic effect of these drugs. Given the greater reproductive efficiency of rodents, the results obtained in the present study raise concern regarding possible fertility impairment in men taking statins and SNRI drugs.

HSPA1L and HSPA1B gene polymorphisms and haplotypes are associated with idiopathic male infertility in Iranian population

OBJECTIVE

Male infertility is a multifactorial disease resulting from the interaction between the genetic and environmental factors. Spermatogenic failure accounts for more than half of male infertility cases. Heat shock proteins (HSPs) are the molecular chaperones that are involved in different developmental stages of spermatogenesis. The current study was planned to investigate the role of HSPA1L rs2227956 and HSPA1B rs1061581 gene polymorphisms in idiopathic male infertility.

STUDY DESIGN

This case-control study was conducted on 516 subjects consisted of 308 patients with idiopathic male infertility and 208 age matched-(±5) control subjects. HSPA1L rs2227956 and HSPA1B rs1061581 polymorphisms were genotyped by PCR-RFLP method.

RESULTS

A significant association with male infertility was found for HSPA1L rs2227956 in genotypes (TT vs CT: OR = 2.049, 95% CI = 1.337-3.139, P = 0.001; TT vs CC: OR = 3.028, 95% CI = 1.100-8.332, P = 0.032). In the dominant genetic model, rs2227956C allele increased the risk of male infertility (OR = 2.049, 95% CI = 1.337-3.139, P = 0.001). Also, the results showed a significant association between the HSPA1B rs1061581GG genotype and male infertility (OR = 2.638, 95% CI: 1.001-4.486, P = 0.001). The rs1061581 G allele was a risk factor for male infertility (OR = 1.657, 95% CI = 1.278-2.148, P < 0.001). Haplotype analysis showed CG and TA (rs2227956/ rs1061581) haplotype affect the risk of male infertility (P < 0.001).

CONCLUSION

HSPA1L rs2227956 and HSPA1B rs1061581 gene polymorphisms are associated with susceptibility to idiopathic male infertility in Iranian population. Further studies in different ethnicity are necessary to confirm these results.

Proteomic profile of human spermatozoa in healthy and asthenozoospermic individuals

Asthenozoospermia is considered as a common cause of male infertility and characterized by reduced sperm motility. However, the molecular mechanism that impairs sperm motility remains unknown in most cases. In the present review, we briefly reviewed the proteome of spermatozoa and seminal plasma in asthenozoospermia and considered post-translational modifications in spermatozoa of asthenozoospermia. The reduction of sperm motility in asthenozoospermic patients had been attributed to factors, for instance, energy metabolism dysfunction or structural defects in the sperm-tail protein components and the differential proteins potentially involved in sperm motility such as COX6B, ODF, TUBB2B were described. Comparative proteomic analysis open a window to discover the potential pathogenic mechanisms of asthenozoospermia and the biomarkers with clinical significance.

Proteolytic degradation of heat shock protein A2 occurs in response to oxidative stress in male germ cells of the mouse

STUDY QUESTION

Does oxidative stress compromise the protein expression of heat shock protein A2 (HSPA2) in the developing germ cells of the mouse testis?

SUMMARY ANSWER

Oxidative stress leads to the modification of HSPA2 by the lipid aldehyde 4-hydroxynonenal (4HNE) and initiates its degradation via the ubiquitin-proteasome system.

WHAT IS KNOWN ALREADY

Previous work has revealed a deficiency in HSPA2 protein expression within the spermatozoa of infertile men that have failed fertilization in a clinical setting. While the biological basis of this reduction in HSPA2 remains to be established, we have recently shown that the HSPA2 expressed in the spermatozoa of normozoospermic individuals is highly susceptible to adduction, a form of post-translational modification, by the lipid aldehyde 4HNE that has been causally linked to the degradation of its substrates. This modification of HSPA2 by 4HNE adduction dramatically reduced human sperm-egg interaction in vitro. Moreover, studies in a mouse model offer compelling evidence that the co-chaperone BCL2-associated athanogene 6 (BAG6) plays a key role in regulating the stability of HSPA2 in the testis, by preventing its ubiquitination and subsequent proteolytic degradation.

STUDY DESIGN, SIZE, DURATION

Dose-dependent studies were used to establish a 4HNE-treatment regime for primary culture(s) of male mouse germ cells. The influence of 4HNE on HSPA2 protein stability was subsequently assessed in treated germ cells. Additionally, sperm lysates from infertile patients with established zona pellucida recognition defects were examined for the presence of 4HNE and ubiquitin adducts. A minimum of three biological replicates were performed to test statistical significance.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Oxidative stress was induced in pachytene spermatocytes and round spermatids isolated from the mouse testis, as well as a GC-2 cell line, using 50-200 µM 4HNE or hydrogen peroxide (H2O2), and the expression of HSPA2 was monitored via immunocytochemistry and immunoblotting approaches. Using the GC-2 cell line as a model, the ubiquitination and degradation of HSPA2 was assessed using immunoprecipitation techniques and pharmacological inhibition of proteasomal and lysosomal degradation pathways. Finally, the interaction between BAG6 and HSPA2 was examined in response to 4HNE exposure via proximity ligation assays.

MAIN RESULTS AND THE ROLE OF CHANCE

HSPA2 protein levels were significantly reduced compared with controls after 4HNE treatment of round spermatids (P < 0.01) and GC-2 cells (P < 0.001) but not pachytene spermatocytes. Using GC-2 cells as a model, HSPA2 was shown to be both adducted by 4HNE and targeted for ubiquitination in response to cellular oxidative stress. Inhibition of the proteasome with MG132 prevented HSPA2 degradation after 4HNE treatment indicating that the degradation of HSPA2 is likely to occur via a proteasomal pathway. Moreover, our assessment of proteasome activity provided evidence that 4HNE treatment can significantly increase the proteasome activity of GC-2 cells (P < 0.05 versus control). Finally, 4HNE exposure to GC-2 cells resulted in the dissociation of HSPA2 from its regulatory co-chaperone BAG6, a key mediator of HSPA2 stability in male germ cells.

LIMITATIONS, REASONS FOR CAUTION

While these experiments were performed using a mouse germ cell-model system, our analyses of patient sperm lysate imply that these mechanisms are conserved between mouse and human germ cells.

WIDER IMPLICATIONS OF THE FINDINGS

This study suggests a causative link between non-enzymatic post-translational modifications and the relative levels of HSPA2 in the spermatozoa of a specific sub-class of infertile males. In doing so, this work enhances our understanding of failed sperm-egg recognition and may assist in the development of targeted antioxidant-based approaches for ameliorating the production of cytotoxic lipid aldehydes in the testis in an attempt to prevent this form of infertility.

LARGE SCALE DATA

Not applicable.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Health and Medical Research Council of Australia (APP1101953). The authors have no competing interests to declare.

A new media without animal component for sperm cryopreservation: motility and various attributes affecting paternal contribution of sperm

PURPOSE

Our aim was the development of a safe sperm cryopreservation New Media (NM), composed of consistent and reproducible components devoid of any animal origin, and evaluation of NM in terms of its effect on sperm structure and function as compared to regularly used yolk media (TYM) (Irvine Scientific).

METHODS

We evaluated patient semen samples and cryopreserved them in duplicates in either NM or TYM. The samples were cryopreserved for either a short term of 1 week or long term of 1 month prior to thawing. The parameters investigated include sperm motility via computer-assisted semen analysis (CASA), sperm concentration, and sperm biomarkers that promote paternal contribution of spermatozoa to fertilization including hyaluronic acid binding, chromatin maturity, apoptotic markers, cytoplasmic retention, and sperm DNA integrity.

RESULTS

As compared to TYM, NM was equally capable of sperm cryopreservation with both short-term and long-term storage in media, and after freeze-thaw and gradient processing of sperm. HA binding of sperm was comparable post thaw in both NM and yolk media. There are also no differences observed between the samples cryopreserved in NM or TYM in terms of their aniline blue staining, CK immunocytochemistry, caspase 3 immunostaining, or DNA nick translation.

CONCLUSIONS

NM has the advantage of being xeno-free, yet in preservation of sperm motility and other sperm attributes, the NM is as effective as the TYM.

Heat Shock Protein A2 (HSPA2): Regulatory Roles in Germ Cell Development and Sperm Function

Among the numerous families of heat shock protein (HSP) that have been implicated in the regulation of reproductive system development and function, those belonging to the 70 kDa HSP family have emerged as being indispensable for male fertility. In particular, the testis-enriched heat shock 70 kDa protein 2 (HSPA2) has been shown to be critical for the progression of germ cell differentiation during spermatogenesis in the mouse model. Beyond this developmentally important window, mounting evidence has also implicated HSPA2 in the functional transformation of the human sperm cell during their ascent of the female reproductive tract. Specifically, HSPA2 appears to coordinate the remodelling of specialised sperm domains overlying the anterior region of the sperm head compatible with their principle role in oocyte recognition. The fact that levels of the HSPA2 protein in mature spermatozoa tightly correlate with the efficacy of oocyte binding highlight its utility as a powerful prognostic biomarker of male fertility. In this chapter, we consider the unique structural and biochemical characteristics of HSPA2 that enable this heat shock protein to fulfil its prominent roles in orchestrating the morphological differentiation of male germ cells during spermatogenesis as well as their functional transformation during post-testicular sperm maturation.

Seminal plasma HSPA2 mRNA content is associated with semen quality

PURPOSE

Cell-free mRNAs (cfmRNAs) were quantitatively measured in human seminal plasma and its relationship with semen quality was investigated.

METHODS

Herein, a prospectively, controlled investigation was performed to study seminal plasma HSPA2 and uPA cfmRNA alterations between 21 asthenozoospermic patients and 16 normozoospermic individuals. Standard semen analysis was performed and seminal plasma cfmRNAs content was measured by real-time quantitative PCR. In addition, the regression analysis between seminal plasma cfmRNAs expression and semen parameters was performed.

RESULTS

Seminal plasma HSPA2, but not uPA cfmRNA indicated significant difference between normozoospermia and asthenozoospermia men (P = 0.02444 and 0.07811, respectively). Negative correlation between HSPA2 cfmRNA and sperm motility (R (2) = 0.213, P = 0.004) as well as sperm concentration (R (2) = 0.133, P = 0.026) were revealed. However, no correlation was found between seminal plasma uPA cfmRNA content and semen parameters.

CONCLUSIONS

Our data suggest that seminal plasma HSPA2 cfmRNA is different between asthenozoospermic and normozoospermic individuals and it might be an indicator for semen quality.

The role of the molecular chaperone heat shock protein A2 (HSPA2) in regulating human sperm-egg recognition

One of the most common lesions present in the spermatozoa of human infertility patients is an idiopathic failure of sperm-egg recognition. Although this unique cellular interaction can now be readily by-passed by assisted reproductive strategies such as intracytoplasmic sperm injection (ICSI), recent large-scale epidemiological studies have encouraged the cautious use of this technology and highlighted the need for further research into the mechanisms responsible for defective sperm-egg recognition. Previous work in this field has established that the sperm domains responsible for oocyte interaction are formed during spermatogenesis prior to being dynamically modified during epididymal maturation and capacitation in female reproductive tract. While the factors responsible for the regulation of these sequential maturational events are undoubtedly complex, emerging research has identified the molecular chaperone, heat shock protein A2 (HSPA2), as a key regulator of these events in human spermatozoa. HSPA2 is a testis-enriched member of the 70 kDa heat shock protein family that promotes the folding, transport, and assembly of protein complexes and has been positively correlated with in vitro fertilization (IVF) success. Furthermore, reduced expression of HSPA2 from the human sperm proteome leads to an impaired capacity for cumulus matrix dispersal, sperm-egg recognition and fertilization following both IVF and ICSI. In this review, we consider the evidence supporting the role of HSPA2 in sperm function and explore the potential mechanisms by which it is depleted in the spermatozoa of infertile patients. Such information offers novel insights into the molecular mechanisms governing sperm function.

The impact of oxidative stress on chaperone-mediated human sperm-egg interaction

STUDY QUESTION

How does oxidative stress impact upon human sperm-egg interaction and in particular the formation of zona pellucida-receptor complexes on the sperm surface?

SUMMARY ANSWER

Oxidative stress during human sperm capacitation resulted in the chemical alkylation of the molecular chaperone heat shock protein A2 (HSPA2), a concomitant reduction in surface expression of the zona pellucida-receptor arylsulphatase A (ARSA) and a severe loss of zona pellucida binding ability.

WHAT IS KNOWN ALREADY

An inability to bind to the zona pellucida is commonly encountered in the defective spermatozoa generated by male infertility patients; however, the underlying mechanisms remain unresolved. Recent studies have revealed that zona pellucida binding is mediated by molecular chaperones, particularly HSPA2, that facilitate the formation of multimeric zona pellucida-receptor complexes on the surface of mammalian spermatozoa during capacitation.

STUDY DESIGN, SIZE, DURATION

Spermatozoa were collected from healthy normozoospermic donors (n = 15). Low levels of oxidative stress were induced in populations of non-capacitated spermatozoa by a 1 h treatment with 4-hydroxynonenal (4HNE) or hydrogen peroxide (H2O2) and then these insults were removed and cells were capacitated for 3 h.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Motility, membrane fluidity, protein tyrosine phosphorylation and lipid raft distribution were evaluated after sperm capacitation to determine the impact of oxidative stress on this process. The surface expression of ARSA and sperm adhesion molecule 1 (SPAM1) was observed using fluorescence microscopy, and the ability of treated cells to interact with homologous human zonae pellucidae was assessed through gamete co-incubation. Proximity ligation was used to evaluate the state of the HSPA2-laden zona pellucida-receptor complex and an immunoprecipitation approach was taken to establish the chemical alkylation of HSPA2 by the cytotoxic lipid aldehyde 4HNE. The validity of these findings was then tested through treatment of oxidatively stressed cells with the nucleophile penicillamine in order to scavenge lipid aldehydes and limit their ability to interact with HSPA2. All experiments were performed on samples pooled from two or more donors per replicate, with a minimum of three replicates.

MAIN RESULTS AND THE ROLE OF CHANCE

The oxidative treatments employed in this study did not influence sperm motility or capacitation-associated changes in membrane fluidity, tyrosine phosphorylation and lipid raft redistribution. However, they did significantly impair zona pellucida binding compared with the capacitated control (P < 0.01). The reduction in zona pellucida binding was associated with the impaired surface expression (P < 0.02) of a zona pellucida-receptor complex comprising HSPA2, SPAM1 and ARSA. Proximity ligation and immunoprecipitation assays demonstrated that impaired zona pellucida binding was, in turn, associated with the chemical alkylation of HSPA2 with 4HNE and the concomitant disruption of this zona pellucida-receptor complex. The use of penicillamine enabled a partial recovery of ARSA surface expression and zona pellucida adherence in H2O2-treated cells. These data suggest that the ability of low levels of oxidative stress to disrupt sperm function is mediated by the production of lipid aldehydes as a consequence of lipid peroxidation and their adduction to the molecular chaperone HSPA2 that is responsible for co-ordinating the assembly of functional zona pellucida-receptor complexes during sperm capacitation.

LIMITATIONS, REASONS FOR CAUTION

While these results extend only to one particular zona pellucida-receptor complex, we postulate that oxidative stress may more broadly impact upon sperm surface architecture. In this light, further study is required to assess the impact of oxidative stress on additional HSPA2-laden protein complexes.

WIDER IMPLICATIONS OF THE FINDINGS

These findings link low levels of oxidative stress to a severe loss of sperm function. In doing so, this work suggests a potential cause of male infertility pertaining to a loss of zona pellucida recognition ability and will contribute to the more accurate diagnosis and treatment of such conditions.

A proteomic analysis on human sperm tail: comparison between normozoospermia and asthenozoospermia

PURPOSE

Asthenozoospermia is a common cause of human male infertility characterized by reduced sperm motility. The molecular mechanism that impairs sperm motility is not fully understood. This study proposed to identify novel biomarkers by focusing on sperm tail proteomic analysis of asthenozoospermic patients.

METHODS

Sperm were isolated from normozoospermic and asthenozoospermic semen samples. Tail fractions were obtained by sonication followed by Percoll gradient. The proteins were extracted by solubilization and subjected to two-dimensional gel electrophoresis (2-DE); then, the spots were analyzed using Image Master 2D Platinum software. The significantly increased/decreased amounts of proteins in the two groups were exploited by matrix-assisted laser desorption-ionization time-of-flight/time-of-flight (MALDI-TOF-TOF) mass spectrometry.

RESULTS

Three hundred ninety protein spots were detected in both groups. Twenty-one protein spots that had significantly altered amounts (p < 0.05) were excised and exploited using MALDI-TOF-TOF mass spectrometry. They led to the identification of the following 14 unique proteins: Tubulin beta 2B; glutathione S-transferase Mu 3; keratin, type II cytoskeletal 1; outer dense fiber protein 2; voltage-dependent anion-selective channel protein 2; A-kinase anchor protein 4; cytochrome c oxidase subunit 6B; sperm protein associated with the nucleus on the X chromosome B; phospholipid hydroperoxide glutathione peroxidase-mitochondrial; isoaspartyl peptidase/L-asparaginase; heat shock-related 70 kDa protein 2; stress-70 protein, mitochondrial; glyceraldehyde-3-phosphate dehydrogenase, testis-specific and clusterin.

CONCLUSION

Fourteen proteins present in different amounts in asthenozoospermic sperm tail samples were identified, four of which are reported here for the first time. These proteins might be used as markers for the better diagnosis of sperm dysfunctions, targets for male contraceptive development, and to predict embryo quality.

Expression, function, and regulation of the testis-enriched heat shock HSPA2 gene in rodents and humans

The HSPA2 gene is a poorly characterized member of the HSPA (HSP70) family. HSPA2 was originally described as testis-specific and expressed at the highest level in pachytene spermatocytes of rodents, the expression of which is not induced by heat shock. HSPA2 is crucial for male fertility. However, recent advances have shown that HSPA2 is expressed in various tumors and in certain types of somatic tissues. In this review, we summarize the current knowledge on the HSPA2 expression pattern, including information on transcriptional, translational, posttranslational, and epigenetic mechanisms which regulate HSPA2 expression. We also present and discuss the current views concerning the functions of the HSPA2 protein in spermatogenetic, somatic, and cancer cells. The knowledge of the properties of HSPA2, although limited, shows this protein as a unique member of the HSPA family. However, understanding whether this protein could become a relevant cancer biomarker or a therapeutically applicable target requires extensive further studies.

Depression of HspA2 in human testis is associated with spermatogenic impairment and fertilization rate in ICSI treatment for azoospermic individuals

PURPOSE

Heat shock protein A2 (HspA2) expression was quantitatively measured in human testis and its relationship with the spermatogenetic status and laboratory outcomes of intracytoplasmic sperm injection (ICSI) was investigated.

METHODS

Testicular tissues of azoospermia men were divided into four groups according to histopahtology: normal spermatogenesiss, hypospermatogenesis, maturation arrest and Sertoli cell-only syndrome (SCOS). HspA2 immunostaining was measured by Image Pro-Plus (IPP) and laboratory outcomes were calculated. The regression analysis between HspA2 expression and Johnsen score of as well as fertilization, cleavage and high quality embryo rate was performed.

RESULTS

HspA2 was strongly present in the cytoplasm of spermatocytes and spermatides in normal testis. However, hypospermatogenesis and maturation arrest testicular tissues demonstrated light staining and no staining for SCOS. Quantitative image analysis showed that there were significant differences among groups (P = 0.000 & P = 0.001). HspA2 exspression was founded significantly correlated spermatogenetic status (R(2) = 0.726, P = 0.000) as well as fertilization rate in ICSI (R(2) = 0.569, P = 0.000).

CONCLUSIONS

The fertilization rate with ICSI is associated with HspA2 expression in the testis from which sperm retrieved and the alteration of HspA2 expression has been involved in spermatogenic impairment.

[Fertilization failure in IVF and ICSI]

OBJECTIVES

To assess male and female clinical and biological parameters that may explain fertilization failure in vitro fertilization (IVF) and IVF with intra-cytoplasmic sperm injection (ICSI).

MATERIAL AND METHODS

Retrospective case-control study including 1282 IVF or ICSI cycles at the centre hospitalier universitaire of Nantes from September 2010 to February 2012. The "Fertilization Failure" group, showing no sign of fertilization, has been compared with the "Control patients" group, getting at least one embryo.

RESULTS

Several significant differences were noted as, in the "Fertilization Failure" group, lower values of antral follicles (P<0.05), of inseminated oocytes (P<0.001) and active sperm (P<0.001) in IVF, and a lower quantity and quality of oocytes (P<0.001) in ICSI. The correlation tests have confirmed a significant association with these parameters. However, the logistic regression tests did not identify explanatory or predictive factor in IVF or ICSI.

CONCLUSION

In our study, in accordance with literature data, impaired sperm parameters were mainly involved in complete fertilization failure in IVF, and a lower oocyte quality in ICSI.

The function of chaperone proteins in the assemblage of protein complexes involved in gamete adhesion and fusion processes

The remarkable complexity of the molecular events governing adhesion and fusion of the male and female gametes is becoming apparent. Novel research suggests that these highly specific cellular interactions are facilitated by multiprotein complexes that are delivered to and/or assembled on the surface of the gametes by molecular chaperones in preparation for sperm-egg interaction. While the activation of these molecular chaperones and the mechanisms by which they shuttle proteins to the surface of the cell remain the subject of ongoing investigation, a compelling suggestion is that these processes are augmented by dynamic membrane microdomains or lipid rafts that migrate to the apical region of the sperm head after capacitation. Preliminary studies of the oocyte plasma membrane have also revealed the presence of lipid rafts comprising several molecular chaperones, raising the possibility that similar mechanisms may be involved in the activation of maternal fusion machinery and the regulation of oocyte plasma membrane integrity. Despite these findings, the analysis of oocyte surface multiprotein complexes is currently lacking. Further analyses of the intermediary proteins that facilitate the expression of key players in sperm-egg fusion are likely to deliver important insights into this unique event, which culminates in the cytoplasmic continuity of the male and female gametes.

Semen Characteristics After Overnight Shipping: Preservation of Sperm Concentrations, HspA2 Ratios, CK Activity, Cytoplasmic Retention, Chromatin Maturity, DNA Integrity, and Sperm Shape

We tested several approaches that can be used to preserve sperm attributes and the objective biochemical markers of sperm maturity and function for assessment in a remote centralized laboratory after overnight shipping of semen samples. Addition of phenyl-methyl-sulfonyl-fluoride (PMSF) to a final concentration of 20 microg/mL semen at 4 degrees C has preserved sperm concentrations and HspA2 isoform ratios, even at room temperature, simulating a shipping delay in moderate ambient temperatures. Regarding the attributes of individual spermatozoa, the patterns of CK-immunocytochemistry (demonstrates cytoplasmic retention in diminished-maturity spermatozoa); aniline blue staining pattern (tests chromatin maturity); sperm shape assessed by both Kruger strict morphology and computer assisted morphometry; and sperm DNA integrity, as tested by DNA nick translation, all remained unchanged. Thus, the PMSF-4 degrees C conditions preserved sperm concentrations and the cytoplasmic and nuclear biomarkers of sperm cellular maturity and function for next-day analysis. This shipping method will facilitate the early detection of subtle changes in semen quality that can affect sperm function, even when there has been no decline in sperm concentrations to signal possible toxic effects. Furthermore, sample preservation will enable investigators to evaluate semen for toxicology studies and for diagnosis of male infertility from remote locations. Home collection of semen should enhance study participation, and semen assessment in centralized laboratories will address concerns regarding interlaboratory variations and quality control.

Immunofluorescence Reveals Ubiquitination of Retained Distal Cytoplasmic Droplets on Ejaculated Porcine Spermatozoa

The purpose of the present study was twofold: 1) to determine if antibodies raised against ubiquitin would recognize antigens associated with the porcine cytoplasmic droplet (CD), and 2) to determine if the same antibody would identify ubiquitinated substrates on the surface of morphologically abnormal boar spermatozoa. Permeabilization with the detergent Triton X-100 (0.05%) showed virtually all CDs to be ubiquitin positive. Distal droplets (DDs) retained in situ on boar spermatozoa were readily labeled following Triton permeabilization, whereas DDs present on nonpermeabilized cells were not. Negative control preparations lacked the ubiquitin staining on the DD. The use of microtubes for fixation and incubation provided clearer images as well as better sperm cell distribution and density than an initial slide-mounted technique. Immunoblotting indicated that larger amounts of ubiquitinated proteins were present in extracts from sperm cells from an ejaculate with an abnormally high percentage of retained DDs (52% DDs) compared to a morphologically normal sample (6% DDs). The primary antibody recognized both mono-ubiquitin of bovine origin (8.5 kd) and human ubiquitin conjugate (35 kd), as demonstrated by Western blot. Preabsorption of the anti-ubiquitin antibody with purified bovine ubiquitin was successful in preventing diaminobenzidine staining of sperm extract from the high DD ejaculate. The presence of antigens recognized by anti-ubiquitin antibodies in the boar sperm CD, coupled with the possibility that superfluous ubiquitin species are detrimental to embryonic development by targeting critical paternally contributed zygotic organelles, raises concerns that retained DDs may be more detrimental to fertility than previously suspected.

Methodology of aniline blue staining of chromatin and the assessment of the associated nuclear and cytoplasmic attributes in human sperm

In this chapter, the laboratory methods for detection of sperm biomarkers that are aimed at identifying arrested sperm development are summarized. These probes include sperm staining with aniline blue for persistent histones, representing a break in the histone-transition protein-protamine sequence, immunocytochemistry with cytoplasmic sperm proteins, highlighting cytoplasmic retention during spermiogenesis, DNA nick translation testing for DNA chain fragmentation due to various reasons, for instance low HspA2 chaperone protein levels, and consequential diminished DNA repair. Finally, we briefly provide references on our work on sperm hyaluronan binding, abnormal Tybergerg sperm morphology, and the increased levels of chromosomal aneuploidies in sperm with developmental arrest. A very interesting aspect of the biomarker field is the discovery (Sati et al, Reprod Biomed Online 16:570-579, 2008) that the various nuclear and cytoplasmic defects detected by the biomarkers are related, and may simultaneously occur within the same spermatozoa as evidenced by a combination of biomarkers, such as aniline blue staining (persistent histones) coupled with cytoplasmic retention, DNA fragmentation, Caspase-3, Tygerberg abnormal morphology, and increased levels of chromosomal aneuploidies. We show examples of this >80% overlap in staining patterns within the same spermatozoa.

Use of hyaluronan in the selection of sperm for intracytoplasmic sperm injection (ICSI): significant improvement in clinical outcomes--multicenter, double-blinded and randomized controlled trial

STUDY QUESTION

Does the selection of sperm for ICSI based on their ability to bind to hyaluronan improve the clinical pregnancy rates (CPR) (primary end-point), implantation (IR) and pregnancy loss rates (PLR)?

SUMMARY ANSWER

In couples where ≤65% of sperm bound hyaluronan, the selection of hyaluronan-bound (HB) sperm for ICSI led to a statistically significant reduction in PLR.

WHAT IS KNOWN AND WHAT THIS PAPER ADDS

HB sperm demonstrate enhanced developmental parameters which have been associated with successful fertilization and embryogenesis. Sperm selected for ICSI using a liquid source of hyaluronan achieved an improvement in IR. A pilot study by the primary author demonstrated that the use of HB sperm in ICSI was associated with improved CPR. The current study represents the single largest prospective, multicenter, double-blinded and randomized controlled trial to evaluate the use of hyaluronan in the selection of sperm for ICSI.

DESIGN

Using the hyaluronan binding assay, an HB score was determined for the fresh or initial (I-HB) and processed or final semen specimen (F-HB). Patients were classified as >65% or ≤65% I-HB and stratified accordingly. Patients with I-HB scores ≤65% were randomized into control and HB selection (HYAL) groups whereas patients with I-HB >65% were randomized to non-participatory (NP), control or HYAL groups, in a ratio of 2:1:1. The NP group was included in the >65% study arm to balance the higher prevalence of patients with I-HB scores >65%. In the control group, oocytes received sperm selected via the conventional assessment of motility and morphology. In the HYAL group, HB sperm meeting the same visual criteria were selected for injection. Patient participants and clinical care providers were blinded to group assignment.

PARTICIPANTS AND SETTING

Eight hundred two couples treated with ICSI in 10 private and hospital-based IVF programs were enrolled in this study. Of the 484 patients stratified to the I-HB > 65% arm, 115 participants were randomized to the control group, 122 participants were randomized to the HYAL group and 247 participants were randomized to the NP group. Of the 318 patients stratified to the I-HB ≤ 65% arm, 164 participants were randomized to the control group and 154 participants were randomized to the HYAL group.

MAIN RESULTS AND THE ROLE OF CHANCE

HYAL patients with an F-HB score ≤65% demonstrated an IR of 37.4% compared with 30.7% for control [n = 63, 58, P > 0.05, (95% CI of the difference −7.7 to 21.3)]. In addition, the CPR associated with patients randomized to the HYAL group was 50.8% when compared with 37.9% for those randomized to the control group (n = 63, 58, P > 0.05). The 12.9% difference was associated with a risk ratio (RR) of 1.340 (RR 95% CI 0.89–2.0). HYAL patients with I-HB and F-HB scores ≤65% revealed a statistically significant reduction in their PLR (I-HB: 3.3 versus 15.1%, n = 73, 60, P = 0.021, RR of 0.22 (RR 95% CI 0.05–0.96) (F-HB: 0.0%, 18.5%, n = 27, 32, P = 0.016, RR not applicable due to 0.0% value) over control patients. The study was originally planned to have 200 participants per arm providing 86.1% power to detect an increase in CPR from 35 to 50% at α = 0.05 but was stopped early for financial reasons. As a pilot study had demonstrated that sperm preparation protocols may increase the HB score, the design of the current study incorporated a priori collection and analysis of the data by both the I-HB and the F-HB scores. Analysis by both the I-HB and F-HB score acknowledged the potential impact of sperm preparation protocols.

BIAS, CONFOUNDING AND OTHER REASONS FOR CAUTION

Selection bias was controlled by randomization. Geographic and seasonal bias was controlled by recruiting from 10 geographically unique sites and by sampling over a 2-year period. The potential for population effect was controlled by adjusting for higher prevalence rates of >65% I-HB that naturally occur by adding the NP arm and to concurrently recruit >65% and ≤65% I-HB subjects. Monitoring and site audits occurred regularly to ensure standardization of data collection, adherence to the study protocol and subject recruitment. Subgroup analysis based on the F-HB score was envisaged in the study design.

GENERALIZABILITY TO OTHER POPULATIONS

The study included clinics using different sperm preparation methods, located in different regions of the USA and proceeded in every month of the year. Therefore, the results are widely applicable.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by Biocoat, Inc., Horsham, PA, USA. The statistical analysis plan and subsequent analyses were performed by Sherrine Eid, a biostatistician. The manuscript was prepared by Kathryn C. Worrilow, Ph.D. and the study team members. Biocoat, Inc. was permitted to review the manuscript and suggest changes, but the final decision on content was exclusively retained by the authors. K.C.W is a scientific advisor to Biocoat, Inc. S.E. is a consultant to Biocoat, Inc. D.W. has nothing to disclose. M.P., S.S., J.W., K.I., C.K. and T.E. have nothing to disclose. G.D.B. is a consultant to Cooper Surgical and Unisense. J.L. is on the scientific advisory board of Origio.

TRIAL REGISTRATION NUMBER

NCT00741494.

The molecular chaperone HSPA2 plays a key role in regulating the expression of sperm surface receptors that mediate sperm-egg recognition

A common defect encountered in the spermatozoa of male infertility patients is an idiopathic failure of sperm–egg recognition. In order to resolve the molecular basis of this condition we have compared the proteomic profiles of spermatozoa exhibiting an impaired capacity for sperm-egg recognition with normal cells using label free mass spectrometry (MS)-based quantification. This analysis indicated that impaired sperm–zona binding was associated with reduced expression of the molecular chaperone, heat shock 70 kDa protein 2 (HSPA2), from the sperm proteome. Western blot analysis confirmed this observation in independent patients and demonstrated that the defect did not extend to other members of the HSP70 family. HSPA2 was present in the acrosomal domain of human spermatozoa as a major component of 5 large molecular mass complexes, the most dominant of which was found to contain HSPA2 in close association with just two other proteins, sperm adhesion molecule 1 (SPAM1) and arylsulfatase A (ARSA), both of which that have previously been implicated in sperm-egg interaction. The interaction between SPAM1, ARSA and HSPA2 in a multimeric complex mediating sperm-egg interaction, coupled with the complete failure of this process when HSPA2 is depleted in infertile patients, provides new insights into the mechanisms by which sperm function is impaired in cases of male infertility.

An investigation of excess residual cytoplasm in human spermatozoa and its distinction from the cytoplasmic droplet

Recent studies have shown cytoplasmic droplets to be normal morphological occurrences in human male spermatozoa. When the cytoplasm around the sperm midpiece is present in large amounts, however, pathological effects may transpire. The cytoplasmic droplet then becomes known as excess residual cytoplasm, which can impair overall sperm function and produce higher levels of reactive oxygen species, potentially leading to male infertility. Though the distinction between cytoplasmic droplets and excess residual cytoplasm has been made, some studies fail to recognize the difference and incorrectly label the latter as a cytoplasmic droplet. This review attempts to clarify excess residual cytoplasm's effect on fertility, examine the enzymes responsible, and suggest tests and possible treatment options for those affected by this defect.

In vitro fertilization/intracytoplasmic sperm injection for male infertility

Progress in the field of assisted reproduction, and particularly micromanipulation, now heralds a new era in the management of severe male factor infertility, not amenable to medical or surgical correction. By overcoming natural barriers to conception, in vitro fertilization and embryo transfer (IVF-ET), subzonal sperm insemination, partial zona dissection, and intracytoplasmatic injection of sperm (ICSI) now offer couples considered irreversibly infertile, the option of parenting a genetically related child. However, unlike IVF, which necessitates an optimal sperm number and function to successfully complete the sequence of events leading to fertilization, micromanipulation techniques, such as ICSI, involving the direct injection of a spermatozoon into the oocyte, obviate all these requirements and may be used to alleviate severe male factor infertility due to the lack of sperm in the ejaculate due to severely impaired spermatogenesis (non-obstructive azoospermia) or non-reconstructable reproductive tract obstruction (obstructive azoospermia). ICSI may be performed with fresh or cryopreserved ejaculate sperm where available, microsurgically extracted epididymal or testicular sperm with satisfactory fertilization, clinical pregnancy, and ongoing pregnancy rates. However, despite a lack of consensus regarding the genetic implications of ICSI or the application and efficacy of preimplantation genetic diagnosis prior to assisted reproductive technology (ART), the widespread use of ICSI, increasing evidence of the involvement of genetic factors in male infertility and the potential risk of transmission of genetic disorders to the offspring, generate major concerns with regard to the safety of the technique, necessitating a thorough genetic evaluation of the couple, classification of infertility and adequate counseling of the implications and associated risks prior to embarking on the procedure. The objective of this review is to highlight the indications, advantages, limitations, outcomes, implications and safety of using IVF/ICSI for male factor infertility to enable a more judicious use of these techniques and maximize their potential benefits while minimizing foreseen complications.

Proteomics-based study on asthenozoospermia: differential expression of proteasome alpha complex

With a view to understand the molecular basis of sperm motility, we have tried to establish the human sperm proteome by two-dimensional PAGE MALDI MS/MS analysis. We report identification of 75 different proteins in the human spermatozoa. Comparative proteome analysis was carried out for asthenozoospermic and normozoospermic patients to understand the molecular basis of sperm motility. Analysis revealed eight proteins (including one unidentified) with altered intensity between the groups. Differential proteins distributed into three functional groups: 'energy and metabolism' (triose-phosphate isomerase, glycerol kinase 2, testis specific isoform and succinyl-CoA:3-ketoacid co-enzyme A transferase 1, mitochondrial precursor); 'movement and organization' (tubulin beta 2C and tektin 1) and 'protein turnover, folding and stress response' (proteasome alpha 3 subunit and heat shock-related 70 kDa protein 2). It was interesting to note that although the proteins falling in the functional group of 'energy and metabolism' are higher in the asthenozoospermic patients, the other two functional groups contain proteins, which are higher in the normozoospermic samples. Validation of results carried out for proteasome alpha 3 subunit by immunoblotting and confocal microscopy, confirmed significant changes in intensity of proteasome alpha 3 subunit in asthenozoospermic samples when compared with normozoospermic controls. Significant positive correlation too was found between proteasome alpha 3 subunit levels and rapid, linear progressive motility of the spermatozoa. In our understanding, this data would contribute appreciably to the presently limited information available about the proteins implicated in human sperm motility.

Sperm chromatin: fertile grounds for proteomic discovery of clinical tools

Sperm are remarkably complex cells with a singularly important mission: to deliver paternal DNA and its associated factors to the oocyte to start a new life. The integrity of sperm DNA is a keystone of reproductive success, which includes fertilization and embryonic development. In addition, the significance in these processes of proteins that associate with sperm DNA is increasingly being appreciated. In this review, we highlight proteomic studies that have identified sperm chromatin proteins with fertility roles that have been validated by molecular studies in model organisms or correlations in the clinic. Up to 50% of male-factor infertility cases in the clinic have no known cause and therefore no direct treatment. In-depth study of the molecular basis of infertility has great potential to inform the development of sensitive diagnostic tools and effective therapies that will address this incongruity. Because sperm rely on testis-specific protein isoforms and post-translational modifications for their development and function, sperm-specific processes are ideal for proteomic explorations that can bridge the research lab and fertility clinic.

Construction of a proteome profile and functional analysis of the proteins involved in the initiation of mouse spermatogenesis

Spermatogenesis is a complex process of terminal differentiation wherein mature sperm are produced. In the first wave of mouse spermatogenesis, different spermatogenic cells appear at specific time points, and their appearance is expected to be accompanied by changes in specific protein expression patterns. In this study, we used 2D-PAGE and MALDI-TOF/TOF technology to construct a comparative proteome profile for mouse testis at specific time points (days 0, 7, 14, 21, 28, and 60 postpartum). We identified 362 differential protein spots corresponding to 257 different proteins. Further cluster analysis revealed 6 expression patterns, and bioinformatics analysis revealed that each pattern was related to many specific cell processes. Among them, 28 novel proteins with unknown functions neither in somatic cells nor germ cells were identified, 8 of which were found to be uniquely or highly expressed in mouse testes via comparison with the GNF SymAtlas database. Further, we randomly selected 7 protein spots and the above 8 novel proteins to verify the expression pattern via Western blotting and RT-PCR, and 6 proteins with little information in testis were further investigated to explore their cellular localization during spermatogenesis by performing immunohistochemistry for the mouse testis tissue. Taken together, the above results reveal an important proteome profile that is functional during the first wave of mouse spermatogenesis, and they provide a strong basis for further research.