Effect of sperm DNA fragmentation on the clinical outcomes for in vitro fertilization and intracytoplasmic sperm injection in women with different ovarian reserves

OBJECTIVE

To investigate effect of sperm DNA fragmentation (SDF) on clinical outcomes of assisted reproductive technology in women with normal ovarian reserve (NOR) versus reduced ovarian reserve (ROR).

DESIGN

Retrospective clinical study.

SETTING

University-affiliated tertiary teaching hospital.

PATIENT(S)

A total of 2,865 consecutive couples undergoing their first in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) cycle.

INTERVENTION(S)

SDF assessed using sperm chromatin dispersion in sperm samples 1-2 months before treatment.

MAIN OUTCOME MEASURE(S)

SDF, IVF, and ICSI outcomes.

RESULT(S)

The grouping criteria were [1] basal follicle stimulating hormone >10 IU/L, [2] antral follicle count <6, and [3] female age ≥38 years. Women fulfilling two of the three criteria were considered to have ROR, and those not meeting any criteria were considered to have NOR. The area under the receiver operating characteristic curve was 0.594 (0.539-0.648) for the ROR group and 0.510 (0.491-0.530) for the NOR group. A cutoff value for SDF to predict the clinical pregnancy rate (CPR) in the ROR group was 27.3%. When the SDF exceeded 27.3%, the live-birth and implantation rates in the ROR group were statistically significantly decreased, but the clinical pregnancy, live-birth, and implantation rates were not affected in the NOR group. The risk of early abortion increased significantly in the NOR group when the SDF exceeded 27.3%.

CONCLUSION(S)

Sperm DNA fragmentation has a greater impact on IVF and ICSI outcomes among women with ROR, so SDF testing may be of particular clinical significance for these couples.

Inhibition of zygotic DNA repair: transcriptome analysis of the offspring in trout (Oncorhynchus mykiss)

Zygotic repair of the paternal genome is a key event after fertilization. Spermatozoa accumulate DNA strand breaks during spermatogenesis and can suffer additional damage by different factors, including cryopreservation. Fertilization with DNA-damaged spermatozoa (DDS) is considered to promote implantation failures and abortions, but also long-term effects on the progeny that could be related with a defective repair. Base excision repair (BER) pathway is considered the most active in zygotic DNA repair, but healthy oocytes contain enzymes for all repairing pathways. In this study, the effects of the inhibition of the BER pathway in the zygote were analyzed on the progeny obtained after fertilization with differentially DDS. Massive gene expression (GE; 61 657 unique probes) was analyzed after hatching using microarrays. Trout oocytes are easily fertilized with DDS and the high prolificacy allows live progeny to be obtained even with a high rate of abortions. Nevertheless, the zygotic inhibition of Poly (ADP-ribose) polymerase, upstream of BER pathway, resulted in 810 differentially expressed genes (DEGs) after hatching. DEGs are related with DNA repair, apoptosis, telomere maintenance, or growth and development, revealing a scenario of impaired DNA damage signalization and repair. Downregulation of the apoptotic cascade was noticed, suggesting a selection of embryos tolerant to residual DNA damage during embryo development. Our results reveal changes in the progeny from defective repairing zygotes including higher malformations rate, weight gain, longer telomeres, and lower caspase 3/7 activity, whose long-term consequences should be analyzed in depth.

Differential gene susceptibility to sperm DNA damage: analysis of developmental key genes in trout

Sperm chromatin in mammals is packaged in different blocks associated to protamines (PDNA), histones (HDNA), or nuclear matrix proteins. Differential packaging has been related to early or late transcription and also to differential susceptibility to genotoxic damage. Genes located in the more accessible HDNA could be more susceptible to injuries than those located in PDNA, being potential biomarkers of paternal DNA damage. Fish sperm chromatin organization is much diversified, some species lacking protamines and some others totally depleted of histones. Analyzing genotoxic damage in a species homogeneously compacted with some sperm nuclear basic protein type, could help in deciphering the clues of differential susceptibility to damage. In the present study we analyzed in rainbow trout the differential susceptibility of nine genes to UV irradiation and H₂O₂ treatment. The absence of histones in the sperm nuclei was confirmed by Western blot. The chromatin fractionation in sensitive and resistant regions to PvuII (presumably HDNA-like and PDNA-like, respectively) revealed that the nine genes locate in the same resistant region. The number of lesions promoted was quantified using a qPCR approach. Location of 8-hydroxyguanosine (8-OHdG) was analyzed by immunocytochemistry and confocal microscopy. UV irradiation promoted similar number of lesions in all the analyzed genes and a homogenous distribution of 8-OHdG within the nuclei. 8-OHdG was located in the peripheral area of the nucleus after H₂O₂ treatment, which promoted a significantly higher number of lesions in developmental-related genes (8.76–10.95 lesions/10 kb) than in rDNA genes (1.05–1.67 lesions/10 kb). We showed for the first time, that differential susceptibility to damage is dependent on the genotoxic mechanism and relies on positional differences between genes. Sensitive genes were also analyzed in cryopreserved sperm showing a lower number of lesions than the previous treatments and a predominant peripheral distribution of oxidative damage (8-OHdG).

The effect of sperm DNA fragmentation on live birth rate after IVF or ICSI: a systematic review and meta-analysis

A systematic review and meta-analysis was conducted to evaluate the relationship between the extent of sperm DNA damage and live birth rate (LBR) per couple and the influence of the method of fertilization on treatment outcome. Searches were conducted on MEDLINE, EMBASE and Cochrane Library. Six studies were eligible for inclusion in the meta-analysis. Overall, LBR increased signficantly in couples with low sperm DNA fragmentation compared with those with high sperm DNA fragmentation (RR 1.17, 95% CI 1.07 to 1.28; P = 0.0005). After IVF and intracytoplasmic sperm injection (ICSI), men with low sperm DNA fragmentation had significantly higher LBR (RR 1.27, 95% CI 1.05 to 1.52; P = 0.01) and (RR 1.11, 95% CI 1.00 to 1.23, P = 0.04), respectively. A sensitivity analysis showed no statistically significant difference in LBR between low and high sperm DNA fragmentation when ICSI treatment was used (RR 1.08, 95% CI 0.39 to 2.96; P = 0.88). High sperm DNA fragmentation in couples undergoing assisted reproduction techniques is associated with lower LBR. Well-designed randomized studies are required to assess the role of ICSI over IVF in the treatment of men with high sperm DNA fragmentation.

Sperm DNA fragmentation index and pregnancy outcome after IVF or ICSI: a meta-analysis

PURPOSE

The purpose of this study was to carry out a meta-analysis for a comprehensive understanding and estimation of the association between sperm DNA Fragmentation Index (DFI) and pregnancy outcome after in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) treatment.

METHODS

Studies concerning the link of DFI with pregnancy outcome were included after literature search of database PUBMED, EMBASE, MEDLINE. Related information was extracted from the eligible studies by two independent authors and a meta-analysis was conducted by using STATA 12.0 software. Pregnancy outcomes consisted of biochemical pregnancy (BP), clinical pregnancy (CP) and pregnancy loss (PL). The studies included for meta-analysis were divided into three groups according to the DFI threshold value (DFI >27 %, 15-27 %, ≤15 % group). The odds ratio (OR ) and their 95 % confidence intervals (95 % CIs) were used to evaluate the association between DFI and pregnancy outcome.

RESULTS

Twenty articles were included in our meta-analysis. The results indicated that infertile couples were more likely to get pregnant if DFI was less than threshold value (For threshold value > 27 % and 15-27 % group, combined overall OR (95 % CI) = 1.437 (1.186-1.742), 1.639 (1.093-2.459) respectively). However, when stratified by DFI detection methods, using sperm chromatin structure assay (SCSA) as the DFI test method, the results indicated a similar CP rate between groups with a high DFI or a lower DFI value (SCSA, For threshold value >27 % and 15-27 % group, combined overall OR (95 % CI) = 1.242(0.978-1.577), 1.480(0.921-2.377) respectively). The meta-analysis based on BP (overall OR (95 % CI) = 0.952 (0.697-1.302)) and PL((For DFI >27 %, 15-27 %, ≤15 % group, OR (95 % CI) = 0.786 (0.491-1.258), 1.509 (0.655-3.476), (0.538 (0.264-1.097) respectively) outcome yielded nonsignificant results.

CONCLUSIONS

The predication value of DFI for IVF or ICSI outcome is not confirmed in our meta-analysis. Further better designed studies with larger subjects involved are needed to better address this issue.

Assessment of density gradient centrifugation (DGC) and sperm chromatin dispersion (SCD) measurements in couples with male factor infertility undergoing ICSI

PURPOSE

To investigate how effectively density gradient centrifugation (DGC) improves sperm nuclear integrity and to determine whether the sperm chromatin dispersion (SCD) test of sperm nuclear integrity in native or DGC-treated semen can predict the outcome of assisted reproductive technology (ART) in couples undergoing intracytoplasmic sperm injection (ICSI).

METHODS

The DNA integrity of spermatozoa from 63 male factor infertility patients undergoing ICSI was analyzed by the SCD test before and after DGC. The predictive value of the sperm DNA fragmentation index (DFI) for ART outcomes was assessed in a cohort of 45 patients who were undergoing fresh embryo transfer. For the analysis, they were divided into pregnant and non-pregnant groups and, independently, into high sperm DFI (DFI > 30%) and low sperm DFI (DFI ≤ 30%) groups. Both raw and DGC semen parameters were examined.

RESULTS

In the asthenospermia and oligozoospermia groups, DGC decreased the sperm DFI from 31.5 ± 19.7 and 28.5 ± 10.3 to 19.2 ± 18.3 and 16.0 ± 12.8, respectively (P < 0.01). DGC decreased the sperm DFI in the severe oligozoospermia group from 41.4 ± 19.0 to 36.3 ± 20.6 (P > 0.01). The pregnant and non-pregnant groups did not differ in their fertilization rate and sperm DFI in native or DGC semen (P > 0.05). There was also no significant difference between the high sperm DFI (DFI > 30%) and low sperm DFI (DFI ≤ 30 %) groups with regard to fertilization rate, implantation rate, and clinical pregnancy rate for both native and DGC semen (P > 0.05). The patients undergoing ICSI with a high sperm DFI had a higher pregnancy loss rate (defined as spontaneous miscarriage or biochemical pregnancy) compared with patients with a low sperm DFI in both the native and DGC semen groups.

CONCLUSIONS

DGC highly significantly reduces sperm DNA fragmentation in the semen of ICSI patients, with the exception of those with severe oligozoospermia. The results of the SCD test of sperm DNA fragmentation in native or DGC semen do not correlate with the fertilization rate, implantation rate, or clinical pregnancy rate in patients undergoing ICSI.

Sperm DNA fragmentation measured by Halosperm does not impact on embryo quality and ongoing pregnancy rates in IVF/ICSI treatments

Sperm DNA fragmentation (SDF) has been proposed to be one of the main markers regarding male infertility. A prospective study was performed to assess primarily whether sperm DNA damage has any impact on embryological data and secondarily on pregnancy rates. This prospective study evaluated the sperm DNA damage in fresh ejaculated sperm samples from couples undergoing IVF/ICSI treatments, using the improved SCD method, known as Halosperm(®) . The results were evaluated by performing statistical analysis with the statistical package of SPSS v17. A total of 156 fresh semen samples derived from 156 couples undergoing 156 IVF/ICSI cycles. From the 156 couples, 139 finally reached the embryo transfer (ET) procedure. Overall, SDF did not correlate with embryological data, while ongoing pregnancy rate/ET was 21.6%. SDF only correlated with sperm characteristics. After the categorisation of SDF (≤35% and >35%), according to the specific references of the method used, embryological data were comparable as also ongoing pregnancy rates. Using the SCD method, sperm DNA damage is associated neither with embryological data nor to pregnancy rates. However, we should not rule out the fact that extremely high DNA damages are associated with total pregnancy failure.

Microscopic varicocelectomy significantly decreases the sperm DNA fragmentation index in patients with infertility

BACKGROUND

Varicocele is associated with high levels of DNA damage in spermatozoa due to oxidative stress and elevated levels of sperm DNA fragmentation, which has been currently proposed to be an essential additional diagnostic test to be recommended for patients with clinical varicocele. The aim of this study was to evaluate the parameters of semen and the DNA fragmentation index (DFI) in patients with varicocele before and after varicocelectomy.

METHODS

The details of 92 consecutive patients were retrospectively analyzed from January 2010 to December 2012. The sperm samples were evaluated according to the World Health Organization Guidelines. Sperm DNA damage, characterized as DFI, was evaluated by sperm chromatin structure assay using flow cytometry.

RESULTS

There was a statistically significant improvement in the semen concentration, the total motile count, the total normal sperm count, and the sperm DNA fragmentation index (DFI; the percentage of sperm with denatured DNA) after varicocelectomy. There was a large decrease in DFI from a preoperative mean of 42.6% to a postoperative mean of 20.5% (P < 0.001). A higher preoperative DFI was associated with a larger decrease in postoperative DFI, and significant negative correlations were observed between the DFI and sperm motility (r = -0.42, P < 0.01).

CONCLUSION

Our data suggest that varicocelectomy can improve multiple semen parameters and sperm DNA damage in infertile men with varicocele. The patients with preoperative defects in those parameters showed greater improvement postoperatively. Further research in this area is needed to understand the exact mechanisms of DNA damage in infertile men with varicocele.

Comparative analysis of three sperm DNA damage assays and sperm nuclear protein content in couples undergoing assisted reproduction treatment

STUDY QUESTION

Is there an association between sperm DNA damage, measured by three different assays, sperm nuclear protein content and clinical outcomes in assisted reproduction treatment (ART)?

SUMMARY ANSWER

Sperm DNA damage measured by terminal deoxynucleotidyltransferase-mediated dUTP nick-end labelling (TUNEL) and the Comet assay were significantly associated with ART outcomes in our single institution study.

WHAT IS KNOWN ALREADY

Abnormal protamine expression is known to be associated with sperm DNA damage and male infertility. A number of studies have shown a significant relationship between sperm DNA damage and ART outcomes. To date, there are no large studies providing direct comparisons of DNA damage tests within the same study population. Thus, the prognostic value for each method remains unknown.

STUDY DESIGN, SIZE, DURATION

Cross-sectional study of 238 men from infertile couples undergoing ART at the University Center for Reproductive Medicine, Utah, USA, between April 2011 and March 2013.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Sperm from men undergoing ART were tested for DNA damage using the alkaline Comet assay, TUNEL and flow cytometric chromatin evaluation (FCCE) assays. Histone retention was analysed using the aniline blue staining method, whereas protamine content (proteins P1 and P2) and ratio were analysed using acid urea gel electrophoresis. The prognostic value of each sperm DNA test to predict clinical pregnancy was calculated.

MAIN RESULTS AND THE ROLE OF CHANCE

Histone retention was associated with sperm DNA damage (P < 0.001), reduced embryo quality (P = 0.005) and clinical pregnancies (P < 0.001). The mean percentage of sperm with DNA damage was significantly higher in sperm from non-pregnant couples compared with that from pregnant couples, as measured by TUNEL assay (15.04 ± 1.16% versus 8.79 ± 0.56%; P < 0.001) and alkaline Comet assay (72.79 ± 2.49% versus 55.86 ± 2.29%; P < 0.001). There was no association between clinical pregnancies and DNA fragmentation index measured by FCCE (12.97 ± 1.46 versus 14.93 ± 1.65; P = 0.379). Of the protamine parameters analysed, only the P1/P2 ratio was associated with sperm count (P = 0.013), men's age (P = 0.037), maturity (P = 0.049) and blastocyst quality (P = 0.012). Histone retention and sperm DNA damage measured by Comet and TUNEL assays were associated with fertilization rate (P < 0.05), embryo quality (P < 0.05) and implantation rate (P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

A potential drawback of this study is that it is cross-sectional. Generally in such studies there is more than one variable that could cause the effect. Analysing sperm is one part of the equation; there are also a number of female factors that have the potential to influence ART outcomes. Therefore, given the large and well-established role of female factors in infertility, normal sperm DNA integrity and protamination do not necessarily ensure clinical pregnancy in ART. Thus, female factors can reduce the prognostic value of sperm DNA tests. Further, our use of native semen instead of prepared sperm may have iatrogenically increased the DNA damage.

WIDER IMPLICATIONS OF THE FINDINGS

Alteration in sperm nuclear protein affects sperm DNA integrity. Further, with the current dataset, TUNEL and Comet assays appeared more predictive of ART success than FCCE.

STUDY FUNDING/COMPETING INTEREST(S)

No personal or direct financial support has been received for any of this work. The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Digital multiplexed mRNA analysis of functionally important genes in single human oocytes and correlation of changes in transcript levels with oocyte protein expression

OBJECTIVE

To investigate functionally important transcripts in single human oocytes with the use of NanoString technology and determine whether observed differences are biologically meaningful.

DESIGN

Analysis of human oocytes with the use of NanoString and immunoblotting.

SETTING

University-affiliated reproductive medicine unit.

PATIENTS

Women undergoing in vitro fertilization.

INTERVENTION

Human oocytes were analyzed with the use of NanoString or immunoblotting.

MAIN OUTCOME MEASURES

The abundance of transcripts for ten functionally important genes-AURKA, AURKC, BUB1, BUB1B (encoding BubR1), CDK1, CHEK1, FYN, MOS, MAP2K1, and WEE2-and six functionally dispensable genes were analyzed with the use of NanoString. BubR1 protein levels in oocytes from younger and older women were compared with the use of immunoblotting.

RESULT(S)

All ten functional genes but none of the six dispensable genes were detectable with the use of NanoString in single oocytes. There was 3- to 5-fold variation in BUB1, BUB1B, and CDK1 transcript abundance among individual oocytes from a single patient. Transcripts for these three genes-all players within the spindle assembly checkpoint surveillance mechanism for preventing aneuploidy-were reduced in the same oocyte from an older patient. Mean BUB1B transcripts were reduced by 1.5-fold with aging and associated with marked reductions in BubR1 protein levels.

CONCLUSION(S)

The abundance of functionally important transcripts exhibit marked oocyte-to-oocyte heterogeneity to a degree that is sufficient to affect protein expression. Observed variations in transcript abundance are therefore likely to be biologically meaningful, especially if multiple genes within the same pathway are simultaneously affected.

ICSI outcome is significantly better with testicular spermatozoa in patients with necrozoospermia: a retrospective study

OBJECTIVE

To determine whether intracytoplasmic sperm injection (ICSI) outcome with testicular sperm is superior to that of ejaculated sperm in men with incomplete necrozoospermia, defined as sperm viability ≥5 to ≤45%.

STUDY DESIGN

Retrospective study at a Reproductive Medicine Center of a tertiary referral hospital. A total of 231 couples with male infertility due to incomplete necrozoospermia underwent 342 ICSI cycles with freshly ejaculated sperm (ICSI-ejaculated) and 182 cycles with testicular sperm (ICSI-TESE).

RESULTS

Overall 1624 MII oocytes were injected in the ICSI-ejaculated group with a fertilisation rate of 60.8%, while in ICSI- TESE cycles the fertilisation rate was 59.6% in 874 MII oocytes. The cleavage rate was higher in ICSI-ejaculated cycles than in ICSI-TESE cycles (96.3% versus 92.9%; p = 0.004). However, the pregnancy and implantation rates per cycle were significantly higher in the ICSI-TESE group (67/182, 36.8% versus 68/342, 19.9% (p = 0.0001); and 23.7% versus 12.7% (p = 0.0001), respectively). The miscarriage rate was similar (ICSI-ejaculated 26.5% versus ICSI-TESE 17.9%, p = 0.301). Live birth rate per cycle in the ICSI-ejaculated group was significantly lower than in the ICSI-TESE (13.7% versus 28.6%, p = 0.0001).

CONCLUSIONS

In cases of persistent necrozoospermia, testicular sperm should be favoured over ejaculated sperm. These data call for more research to understand the pathophysiology of refractory necrozoospermia.

Sperm selection: effect on sperm DNA quality

The selection of spermatozoa without DNA fragmentation and chromosomal diseases prior to assisted reproductive techniques helps to optimize the outcome of the treatment; in particular, sperm selection prior to in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) is crucial. In fact, although ICSI has been successfully and safely applied worldwide for almost 20 years, at the present time we have no real knowledge regarding the hypothetical long-term side effects on ICSI adults, given the increased likelihood of spermatozoa with defective nuclear content fertilizing oocytes.In the case of DNA damage, the basal sperm DNA fragmentation rate can be significantly reduced by some sperm processing procedures that improve the percentage of spermatozoa with normal chromatin structure by filtering out DNA-damaged spermatozoa. After this first step, new advances in micromanipulation can be performed to choose the "ideal" mature spermatozoa for ICSI, reducing potential damage to the gametes. In fact, it is possible to prevent fertilization by DNA-damaged and chromosomal-unbalanced spermatozoa by selecting ICSI sperm by maturation markers such as hyaluronic acid or other zona pellucida receptors. Furthermore, novel noninvasive imaging techniques can be valid tools for helping in the morphological selection of ICSI spermatozoa.

Evaluation of potential protein biomarkers in patients with high sperm DNA damage

The laboratory evaluation of male infertility remains an essential area of research as 40-60% of infertility cases are attributable to male-related factors. Current sperm analysis methods add only partial information on sperm quality and fertility outcomes. The specific underlying cause of infertility in most cases is unknown, while a proportion of male infertility could be caused by molecular factors such as the absence or abnormal expression of some essential sperm proteins. The objective of this study was to screen for associations between sperm protein profiles and sperm concentration, motility, and DNA fragmentation index in patients undergoing fertility evaluation in a clinical setting. Based on those parameters, semen samples were categorized as either normal or abnormal. We screened 34 semen samples with various abnormal parameters and compared them to 24 normal control samples by using one dimensional (1-D) gel electrophoresis and mass-spectrometry. In this study, we anticipated to establish a normal sperm parameter profile which would be compared to abnormal sperm samples and reveal candidate proteins. Our preliminary results indicate that no normal uniform profile could be established, which affirms the complexity of male fertility and confirms the limitations of standard semen analysis. Four main protein groups were identified in correlation with abnormal DNA fragmentation and/or motility. The first group included sperm nuclear proteins such as the SPANX (sperm protein associated with the nucleus on the X chromosome) isoforms and several types of histones. The second group contained mitochondria-related functions and oxidative stress proteins including Mitochondrial Ferritin, Mitochondrial Single-Stranded DNA Binding Protein, and several isoforms of Peroxiredoxins. Two other protein groups were related to sperm motility such as microtubule-based flagellum and spindle microtubule as well as proteins related to the ubiquitin-proteasome pathway. Further research is required in order to characterize these potential biomarkers of male fertility potential.

Structural and functional integrity of spermatozoa is compromised as a consequence of acute uropathogenic E. coli-associated epididymitis

Uropathogenic Escherichia coli (UPEC)-associated epididymitis is commonly diagnosed in outpatient settings. Although the infection can be successfully cleared using antimicrobial medications, 40% of patients unexplainably show persistent impaired semen parameters even after treatment. Our aim was to investigate whether pathogenic UPEC and its associated virulence factor hemolysin (hlyA) perturb the structural and functional integrity of both the epididymis and sperm, actions that may be responsible for the observed impairment and possibly a reduction of fertilization capabilities. Semen collected from patients diagnosed with E. coli-only related epididymitis showed that sperm counts were low 14 days postantimicrobial treatment regardless of hlyA status. At Day 84 following treatment, hlyA production correlated with approximately 4-fold lower sperm concentrations than in men with hlyA-negative strains. In vivo experiments with the hlyA-producing UPEC CFT073 strain in a murine epididymitis model showed that just 3 days postinfection, structural damage to the epididymis (epithelial damage, leukocyte infiltration, and edema formation) was present. This was more severe in UPEC CFT073 compared to nonpathogenic E. coli (NPEC 470) infection. Moreover, pathogenic UPEC strains prematurely activated the acrosome in vivo and in vitro. Raman microspectroscopy revealed that UPEC CFT073 undermined sperm integrity by inducing nuclear DNA damage. Consistent with these observations, the in vitro fertilization capability of hlyA-treated mouse sperm was completely abolished, although sperm were motile. These findings provide new insights into understanding the possible processes underlying clinical manifestations of acute epididymitis.

Are sperm DNA fragmentation, hyperactivation, and hyaluronan-binding ability predictive for fertilization and embryo development in in vitro fertilization and intracytoplasmic sperm injection?

OBJECTIVE

To determine the diagnostic value of the following sperm function tests in predicting the fertilizing ability of spermatozoa in conventional in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI): hyaluronan-binding assay (HBA), DNA fragmentation (Halosperm), and hyperactivity.

DESIGN

Prospective study.

SETTING

University medical center.

PATIENT(S)

133 couples undergoing infertility treatment with IVF/ICSI.

INTERVENTION(S)

Analysis of sperm DNA fragmentation, hyaluronan-binding ability, and hyperactivation on washed semen samples used for the insemination of oocytes.

MAIN OUTCOME MEASURE(S)

Correlation between the results of sperm function tests and the fertilization rate (FR) or embryo quality (EQ) after IVF and ICSI. Comparison of the sperm DNA fragmentation, hyperactivation, and hyaluronan binding ability between cycles with less than 50% (group 1) and more than 50% (group 2) of oocytes fertilized after IVF.

RESULT(S)

Both FR and EQ in IVF cycles negatively correlated with sperm DNA fragmentation. Furthermore, a positive correlation was observed between FR and hyaluronan-binding ability or induced hyperactivity. The semen samples from the IVF cycles with low FR (group 1) were characterized by statistically significantly higher sperm DNA fragmentation and lower hyaluronan-binding ability in comparison with semen samples from the group with high levels of fertilization (group 2). In ICSI cycles, no relationship was found between sperm function tests and FR or EQ.

CONCLUSION(S)

The Halosperm test, the HBA test, and induced hyperactivity are useful in predicting the ability of spermatozoa to fertilize oocytes in IVF and are helpful in distinguishing semen samples suitable for IVF or ICSI.

Epididymis response partly compensates for spermatozoa oxidative defects in snGPx4 and GPx5 double mutant mice

We report here that spermatozoa of mice lacking both the sperm nucleaus glutathione peroxidase 4 (snGPx4) and the epididymal glutathione peroxidase 5 (GPx5) activities display sperm nucleus structural abnormalities including delayed and defective nuclear compaction, nuclear instability and DNA damage. We show that to counteract the GPx activity losses, the epididymis of the double KO animals mounted an antioxydant response resulting in a strong increase in the global H₂O₂-scavenger activity especially in the cauda epididymis. Quantitative RT-PCR data show that together with the up-regulation of epididymal scavengers (of the thioredoxin/peroxiredoxin system as well as glutathione-S-transferases) the epididymis of double mutant animals increased the expression of several disulfide isomerases in an attempt to recover normal disulfide-bridging activity. Despite these compensatory mechanisms cauda-stored spermatozoa of double mutant animals show high levels of DNA oxidation, increased fragmentation and greater susceptibility to nuclear decondensation. Nevertheless, the enzymatic epididymal salvage response is sufficient to maintain full fertility of double KO males whatever their age, crossed with young WT female mice.

Mechanisms and clinical correlates of sperm DNA damage

Among the different DNA anomalies that can be present in the male gamete, DNA fragmentation is the most frequent, particularly in infertile subjects. There is now consistent evidence that a sperm containing fragmented DNA can be alive, motile, morphologically normal and able to fertilize an oocyte. There is also evidence that the oocyte is able to repair DNA damage; however, the extent of this repair depends on the type of DNA damage present in the sperm, as well as on the quality of the oocyte. Thus, it is important to understand the possible consequences of sperm DNA fragmentation (SDF) for embryo development, implantation, pregnancy outcome and the health of progeny conceived, both naturally and by assisted reproductive technology (ART). At present, data on the consequences of SDF for reproduction are scarce and, in many ways, inconsistent. The differences in study conclusions might result from the different methods used to detect SDF, the study design and the inclusion criteria. Consequently, it is difficult to decide whether SDF testing should be carried out in fertility assessment and ART. It is clear that there is an urgent need for the standardisation of the methods and for additional clinical studies on the impact of SDF on ART outcomes.

In situ visualization of damaged DNA in human sperm by Raman microspectroscopy

BACKGROUND

Beyond determining the percentage of damaged sperm, current methods of DNA assessment are of limited clinical utility as they render the sample unusable. We evaluated Raman microspectroscopy, a laser-based non-invasive technique that provides detailed chemical 'fingerprints' of cells and which potentially could be used for nuclear DNA-based sperm selection.

METHODS

Eight healthy donors provided ejaculates. After system optimization, a minimum of 200 air-dried sperm/sample/donor, prior to/and after UVB irradiation, were assessed by two observers. Spectra were analysed by Principal Component, Spectral Angle and Wavelet Analyses.

RESULTS

Spectra provided a chemical map delineating each sperm head region. Principal Component Analysis showed clear separation between spectra from UV-irradiated and untreated samples whilst averaged data identified two regions of interest (1040 and 1400 cm(-1)). Local spectral analysis around the DNA PO(4) backbone peak (1042 cm(-1)), showed that changes in this region were indicative of DNA damage. Wavelet decomposition confirmed both the 1042 cm(-1) shift and a second UVB susceptible region (1400-1600 cm(-1)) corresponding to protein-DNA interactions. No difference was found between observer measurements.

CONCLUSIONS

Raman microspectroscopy can provide accurate and reproducible assessment of sperm DNA structure and the sites and location of damage.

Sperm chromatin dispersion test in the assessment of DNA fragmentation and aneuploidy in human spermatozoa

Sperm DNA damage is thought to be increased in men with male factor infertility. Previous studies suggest a correlation between sperm DNA fragmentation and aneuploidy. The sperm chromatin dispersion (SCD) test was modified to produce the Halosperm Kit. The SCD-fluorescent in-situ hybridization (FISH) test allows the simultaneous detection of DNA fragmentation and aneuploidy on the same sperm cell. The objectives of this study were to validate the SCD, SCD-FISH and Halosperm tests for the analysis of sperm DNA fragmentation and compare them to the sperm chromatin structure assay (SCSA). Semen samples from 20 males undergoing IVF/intracytoplasmic sperm injection were processed using FISH, SCD-FISH, SCD and Halosperm, and compared with SCSA results. There was a significant difference between FISH and SCD-FISH results in the detection of aneuploidy (P=0.000) and the level of sperm DNA fragmentation in the samples subjected to SCSA and SCD (P=0.001) or SCSA and SCD-FISH (P=0.001). There was no significant correlation between DNA fragmentation and aneuploidy. If sperm aneuploidy is to be determined, more reliable results will be obtained if FISH is performed rather than SCD-FISH. A lack of validation and unknown clinical significance question the value of DNA fragmentation assays. DNA damage in the male germ line may result in adverse clinical outcomes and the pathophysiology and clinical consequences of sperm DNA damage are being actively researched. Many DNA fragmentation assays such as the Halosperm Kit have been developed recently and are now available at a commercial level. Unfortunately, aimed at vulnerable couples with difficulty conceiving, many of these tests have not been clinically validated. Despite its plausible appeal and fervour of its supporters, the benefits of widespread DNA testing that only achieves the distressing of couples with the knowledge that effectual therapeutic strategies are absent are questionable. Commercially, however, it is no doubt lucrative. Analysis of gametes prior to the initiation of an IVF cycle may improve the quality of embryos transferred. The clinical and scientific community considers it a matter of urgency to translate the basic science behind how a cell prepares for fertilization into routine clinical practice. However, it is equally important, if not more, to allow the science behind such applications to draw level with its practice before its widespread implementation.

Aneuploidy and DNA fragmentation in sperm of carriers of a constitutional chromosomal abnormality

Among various causes responsible for infertility, it has been admitted for a long time that male infertility can be due to impaired spermatogenesis and/or balanced structural chromosomal abnormalities. Sperm DNA fragmentation is also considered as another cause of infertility. Most of the studies on male infertility have concerned either aneuploidy in the sperm of carriers of constitutional chromosomal abnormalities or sperm DNA fragmentation. This review is aimed at analyzing these 2 parameters in the same patients. Furthermore, we present work on the study of these 2 parameters in the same gametes of 4 carriers of a balanced chromosomal abnormality. Meiotic segregation was analyzed by fluorescent in situ hybridization and DNA fragmentation was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. It was shown that aneuploidy and DNA fragmentation were increased in the sperm of carriers of a balanced chromosomal abnormality. For all 4 carriers of a balanced structural abnormality, there was a 2-5 times higher proportion of spermatozoa with unbalanced chromosomal content and fragmented DNA than among those with normal/balanced content. Moreover, we found a non-random distribution with more gametes with DNA fragmentation when these arose from a particular segregation mode. The mechanism which would tend to explain our results is abortive apoptosis. In conclusion, both meiotic segregation and DNA fragmentation studies should be integrated in the genetic exploration of male carriers of a chromosomal structural abnormality.

Use of zona pellucida-bound sperm for intracytoplasmic sperm injection produces higher embryo quality and implantation than conventional intracytoplasmic sperm injection

This goal of this study was to compare the outcomes of conventional intracytoplasmic sperm injection (ICSI; control group, n = 53 couples) and a modified ICSI technique using zona pellucida (ZP)-bound sperm for injection of oocytes (test group, n = 53 couples). The proportion of high-quality embryos (grades 1 and 2) and implantation rate were significantly higher in the test group than in the control group, but the difference in fetal heart pregnancy rate was not significant despite seven more pregnancies being obtained in the test group (26 pregnancies) versus the control group (19 pregnancies) following fresh embryo transfers.