Dynamics of sperm DNA damage in fresh versus frozen-thawed and gradient processed ejaculates in human donors

A new cryotop vial device system provides an aseptic cryoprotectant-free and centrifuge-free cryopreservation of human spermatozoa (a closed system)

Single sperm cryopreservation is a new method to preserve small numbers of spermatozoa in small droplets. So far, several devices have been introduced for this technique, but more studies are needed for its optimization. The aim of this study was optimizing the previous device for low number of spermatozoa and low volume semen, which led to design of Cryotop Vial device. Normal semen samples from 25 patients were prepared by swim-up method and divided into four groups: Fresh (F), Rapid freezing (R) and ultra-rapid freezing with Cryotop Device (CD) and Cryotop Vial Device (CVD). In R group, the diluted sperm suspension with sperm freezing medium was cooled in the vapor phase and then immersed in liquid nitrogen. Ultra rapid freezing was performed with sucrose in small volume using the Cryotop Device (CD) or Cryotop Vial Device (CVD). Sperm viability, motility, fine morphology, mitochondrial activity and DNA fragmentation were assessed in all samples. All sperm parameters decreased significantly in all the cryo groups compared to the fresh group. The comparison between the cryo groups showed that progressive motility (69.28 ± 6.82 vs. 55.68 ± 9.04, and 54.76 ± 5.34, p < 0.001) and viability (77.36 ± 5.48 vs.68.84 ± 8.51, p < 0.001, and 70.04 ± 7.44, P = 0.002) were significantly higher in the CVD compared to the CD and R groups respectively. DNA fragmentation was also significantly lower in both ultra-rapid freezing groups (CD and CVD) compared to the R group. Fine morphology and mitochondrial activity were not different between the cryo groups. The CVD as a cryoprotectant and centrifuge-free technique preserved sperm motility, viability and DNA integrity after cryopreservation better than other groups.

Sperm selection with hyaluronic acid improved live birth outcomes among older couples and was connected to sperm DNA quality, potentially affecting all treatment outcomes

STUDY QUESTION

What effects did treatment using hyaluronic acid (HA) binding/selection prior to ICSI have on clinical outcomes in the Hyaluronic Acid Binding sperm Selection (HABSelect) clinical trial?

SUMMARY ANSWER

Older women randomized to the trial's experimental arm (selection of sperm bound to immobilized (solid-state) HA) had the same live birth rates as younger women, most likely a result of better avoidance of sperm with damaged DNA.

WHAT IS KNOWN ALREADY

Recent randomized controlled trials (RCTs) investigating the efficacy of HA-based sperm selection prior to ICSI, including HABSelect, have consistently reported reductions in the numbers of miscarriages among couples randomized to the intervention, suggesting a pathological sperm-mediated factor mitigated by prior HA-binding/selection. The mechanism of that protection is unknown.

STUDY DESIGN, SIZE, DURATION

The original HABSelect Phase 3 RCT ran from 2014 to 2017 and included 2752 couples from whom sperm samples used in control (ICSI) and intervention (Physiological IntraCytoplasmic Sperm Injection; PICSI) arms of the trial were stored frozen for later assessment of DNA quality (DNAq). The trial overlapped with its mechanistic arm, running from 2016 to 2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

As miscarriage reduction was a significant secondary outcome of the trial, samples (n = 1247) selected for the mechanistic analysis were deliberately enriched for miscarriage outcomes (n = 92 or 7.4%) from a total of 154 miscarriages (5.6%) among all (n = 2752) couples randomized by stratified random sampling. Values from fresh semen samples for sperm concentration (mml), percentage forward progressive motility and percentage HA-binding score (HBS) were obtained before being processed by differential density gradient centrifugation or (rarely) by swim-up on the day of treatment. Surplus sperm pellets were recovered, aliquoted and cryopreserved for later analysis of DNAq using slide-based Comet, TUNEL, acridine orange (AO) and the sperm chromatin dispersion (SCD) assays. Following their classification into normal and abnormal sample subcategories based on reference values for sperm concentration and motility, relationships with HBS and DNAq were examined by Spearman correlation, Student's t-tests, Mann Whitney U tests, and logistic regression (univariable and multivariable). Parsimonious selection enabled the development of models for exploring and explaining data trends. Potential differences in future cumulative pregnancy rates relating to embryo quality were also explored.

MAIN RESULTS AND THE ROLE OF CHANCE

Results from the 1247 sperm samples assayed for HBS and/or DNAq, generated data that were considered in relation to standard physiological measures of (sperm) vitality and to treatment outcomes. All measures of HBS and DNAq discriminated normal from abnormal sperm samples (P < 0.001). SCD correlated negatively with the Comet (r = -0.165; P < 0.001) and TUNEL assays (r = -0.200; P < 0.001). HBS correlated negatively with AO (r = -0.211; P < 0.001), Comet (r = -0.127; P < 0.001) and TUNEL (r = -0.214; P < 0.001) and positively with SCD (r = 0.255; P < 0.001). A model for predicting live birth (and miscarriage) rates included treatment allocation (odds ratio: OR 2.167, 95% CI 1.084-4.464, P = 0.031), female age (OR 0.301, 95% CI 0.133-0.761, P = 0.013, per decade) and the AO assay (OR 0.79, 95% CI 0.60-1. 02.761, P = 0.073, per 10 points rise). A model predicting the expected rate of biochemical pregnancy included male age (OR 0.464, 95% CI 0.314-0.674, P < 0.001, per decade) and the SCD assay (OR 1.04, 95% CI 1.007-1.075, P = 0.018, per 10 point rise). A model for conversion from biochemical to clinical pregnancy did not retain any significant patient or assay variables. A model for post-injection fertilization rates included treatment allocation (OR 0.83, 95% CI 0.75-0.91, P < 0.001) and the Comet assay (OR 0.950, 95% CI 0.91-1.00, P = 0.041).

LIMITATIONS, REASONS FOR CAUTION

HABSelect was a prospective RCT and the mechanistic study group was drawn from its recruitment cohort for retrospective analysis, without the full benefit of randomization. The clinical and mechanistic aspects of the study were mutually exclusive in that measures of DNAq were obtained from residual samples and not from HA-selected versus unselected sperm. Models for fitting mechanistic with baseline and other clinical data were developed to compensate for variable DNAq data quality. HABSelect used a solid-state version of PICSI and we did not assess the efficacy of any liquid-state alternatives. PICSI reduced fertilization rates and did not improve the outlook for cumulative pregnancy rates.

WIDER IMPLICATIONS OF THE FINDINGS

Notwithstanding the interventional effect on fertilization rates and possibly blastocyst formation (neither of which influenced pregnancy rates), poor sperm DNAq, reflected by lower HBS, probably contributed to the depression of all gestational outcomes including live births, in the HABSelect trial. The interventional avoidance of defective sperm is the best explanation for the equalization in live birth rates among older couples randomized to the trial's PICSI arm. As patients going forward for assisted conception cycles globally in future are likely to be dominated by an older demographic, HA-based selection of sperm for ICSI could be considered as part of their treatment plan.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by the National Institute for Health Research (NIHR) EME (Efficacy and Mechanism Evaluation)-11-14-34. National Research Ethics Service approval 11/06/2013: 13/YH/0162. S.L. is CEO of ExamenLab Ltd (company number NI605309).

TRIAL REGISTRATION NUMBER

ISRCTN99214271.

The effect of paternal age on intracytoplasmic sperm injection outcome in unexplained infertility

Objective

: To examine the effect of paternal age on intracytoplasmic sperm injection (ICSI) outcomes in unexplained infertility.

Subjects and Methods

: This retrospective study, done at the Hamad Medical Corporation, Doha, Qatar screened infertile couples who underwent ICSI between 2014 and 2019 for the inclusion and exclusion criteria defining 'unexplained infertility'. Couples recruited were allocated into two groups: Group A (paternal age <35 years) and Group B (paternal age ≥35 years). Baseline characteristics, investigations including semen and advanced sperm function tests and ICSI records were compared for primary outcomes such as fertilisation, cleavage, clinical pregnancy, miscarriage and live birth; and secondary outcomes such as semen parameters and advanced sperm functions (DNA fragmentation index and oxidation reduction potential).

Results

: We found that final pregnancy outcomes including clinical pregnancy rate (P = 0.231), live-birth rate (P = 0.143), and miscarriage rates (P = 0.466) were not significantly different between the two age groups. Normal fertilisation (P = 0.01) and cleavage rate after ICSI (P = 0.001) were statistically significant when the age groups were compared. Also, normal sperm morphology was found to be significantly different (P = 0.041).

Conclusions

: Advanced paternal age affects sperm morphology, fertilisation and embryo cleavage in ICSI but does not appear to affect clinical pregnancy, miscarriage or live-birth rates. ICSI appears to be a valid fertility treatment option in advancing paternal age.

DNA fragmentation of human spermatozoa: Simple assessment of single- and double-strand DNA breaks and their respective dynamic behavioral response

BACKGROUND

Procedures to detect sperm DNA fragmentation (SDF), like the sperm chromatin dispersion (SCD) test, determine the "global" SDF without discriminating between spermatozoa with single-strand DNA breaks only (SDF-SSBs) and those containing double-strand DNA breaks (SDF-DSBs).

OBJECTIVES

(a) To validate a test to distinguish human spermatozoa with massive DSBs (DSB-SCD assay), (b) to study the baseline SDF-SSBs and SDF-DSBs, and (c) to assess their dynamics in vitro.

MATERIALS AND METHODS

(a) SDF-DSBs were determined by visualization of diffused DNA fragments from spermatozoa lysed under non-denaturing conditions. This was validated by in vitro incubation with DNase I and the comet assay. (b) Baseline SDF-DSBs and SDF-SSBs were determined in ejaculates from 95 males. (c) Their dynamic appearance was studied in samples untreated or exposed to hyperthermia, acidic pH, nitric oxide released by sodium nitroprusside (SNP), and the metabolic energy inhibitors 2-deoxy-D-glucose and antimycin A.

RESULTS

(a) DNase I and comet assay experiments confirmed that the assay successfully determined SDF-DSBs. (b) The higher the SDF of the semen sample, the higher the frequency of SSBs, whereas DSBs behaved independently. Abnormal samples showed higher SDF than normozoospermic, the difference being only significant for SDF-SSBs. (c) During the first hours of incubation, the linear rate of increase in SDF-SSBs was 3.7 X higher than that of SDF-DSBs. All hazardous agents accelerated the SDF rate when compared to untreated spermatozoa, primarily being associated with SDF-SSBs. SNP treatment was the most damaging, rapidly inducing spermatozoa with SSBs which progressively evolved to DSBs. Remarkably, this phenomenon was also evidenced after acute SNP exposure, revealing cryptic sperm damage.

CONCLUSION

The DSBs-SCD is an easy complement for SDF assessment. The dynamic study of SSBs and DSBs may improve the evaluation of sperm quality in clinical settings, particularly "unmasking" the presence of non-specific cryptic sperm damage that might otherwise go undetected.

Modern human sperm freezing: Effect on DNA, chromatin and acrosome integrity

OBJECTIVE

Presence of vitrification method in sperm freezing and the introduction of solid surface vitrification beside rapid freezing in vapour, opens an easy and safe way to help infertility centres. While the effects of cryopreservation on motility, morphology and viability of sperm are documented, the question of the probable alteration of sperm DNA, chromatin and acrosome integrity after freezing and thawing procedures in different methods is still controversial.

MATERIALS AND METHODS

Normal sample were collected according to WHO strict criteria. Sperm suspensions were mixed 1:1 with 0.5 M sucrose and divided into four equal aliquots for freezing: fresh, nitrogen direct immersion vitrification (Vit), solid surface vitrification (SSV) and in vapour (Vapour). Sperm suspensions were transferred into a 0.25 ml sterile plastic. Then straw was inserted inside the 0.5 ml straw. For thawing, the straws were immersed in a 42 °C water bath. Beside the sperm parameters, we assessed the acrosome reaction by double staining, chromatin integrity by toluidine blue (Tb) and chromomycin A3 (CMA3) and DNA integrity by terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) respectively.

RESULTS

In progressive motility, the highest rate occurred in Vit (39.9 ± 13.3). Moreover, the lowest rate of immotile sperm was in Vit (32.7 ± 16.3). In normal morphology, the group Vit was similar to the fresh, while SSV and Vapour were significantly different from the fresh. The percentage of acrosome-reacted sperms was more in Vit (81.3 ± 10.2) than the fresh group. TUNEL+ results showed that DNA fragmentation was significantly increased in Vit (p-value = 0.025). While in SSV and Vapour results were comparable to fresh. There was a significant correlation between TUNEL+ and normal morphology, TB, CMA3 and presence of intact acrosome.

CONCLUSION

Sperm in Vapour was healthier in terms of DNA, chromatin and acrosome integrity. In contrast of higher motility and normal morphology; DNA, chromatin and acrosome integrity were decreased in Vit. However, these findings were more acceptable in SSV or Vapour.

Influence of extended incubation time on Human sperm chromatin condensation, sperm DNA strand breaks and their effect on fertilisation rate

The purpose of this study was to determine influence of extended incubation time on sperm chromatin condensation and DNA strand breaks and their effect on fertilisation rate. Forty couples undergoing ICSI therapy were included. Semen was prepared by PureSperm gradient centrifugation and divided into two parts. The first part (G1) was used immediately for ICSI, whereas the second part (G2) was kept in the incubator at 37°C, 5% and 90% Humidity for 5 hr, and thereafter, the capacitated spermatozoa were used for ICSI. The TUNEL test and chromomycin CMA3 were used to evaluate the DNA strand breaks and chromatin condensation respectively. The percentage of condensed chromatin was 73.92 ± 12.70 in the group 1 and 81.13 ± 10.31% in group 2 (p = .001). However, the double-strand breaks were 11.15 ± 8.67% in G.1 and 16.30 ± 11.12% in G.2. (p = .001). Fertilisation rate in the (Group 1) was 62.45% and 69.17% in (Group 2). There was a positive correlation between condensed chromatin and fertilisation rate (r = 0.846, p = .001) and a negative correlation with DNA double-strand breaks (r = -0.802; p = .001). In conclusion, the prolonged sperm incubation (5 hr) leads to a higher chromatin condensation and to a significantly increased number of DNA strands double breaks with no influence on fertilisation rates.

Sperm DNA fragmentation in donors and normozoospermic patients attending for a first spermiogram: Static and dynamic assessment

Static assessment of sperm DNA Fragmentation (SDF at the time of ejaculation or sperm thawing when cryopreserved) and the dynamic assessment of SDF (SDF assessed after T2 hr, T6 hr and T24 hr of sperm thawing) were used to establish cut-off values associated with sperm donors when compared with closely related normozoospermic patients. Cryopreserved samples from donors revealed SDF levels two times lower in comparison with the patients. Donor sperm DNA exhibited a 2.5 times higher longevity when compared with the patients. Static values of SDF after thawing of approximately 11% identify the donors with a 71% of sensitivity and 84% specificity. With respect to the dynamic assessment, SDF increases of 2.3 per hr during the first 2 hr of incubation identify the donors with 70% of sensitivity and 66% of specificity. Creating the Rate of Combined Damage (RCD) defined as the product of SDF-T0 by the increase in the damage registered during the first 2 hr of incubation (r-SDF-T0-2 ), an index of RCD = 22.2 units has an identification capacity of donors with a 78% sensitivity and 77% specificity. Such cut-off values could be used to characterise donors with high chromatin resistance to damage when meeting the above-established criteria.

Long-term clinical outcomes of testicular sperm extraction and intracytoplasmic sperm injection for infertile men

Purpose

To find the best methods to achieve the highest pregnancy and birth rates for couples needing testicular sperm extraction (TESE)‐intracytoplasmic sperm injection (ICSI).

Methods

Retrospectively studied were 801 patients with male factor infertility who had undergone TESE‐ICSI between April, 1996 and July, 2016 and who had been categorized into four groups: obstructive azoospermia (OA); non‐obstructive azoospermia (NOA); Klinefelter syndrome (KS); and cryptozoospermia (Crypt). The sperm retrieval rate, hormone levels, fertilization rate (FR), pregnancy rate (PR), and birth rate (BR) after ICSI among three groups were compared: fresh testicular sperm (FS)‐fresh oocytes (FO) (Group I); frozen‐thawed testicular sperm‐FO (Group II); and FS‐vitrified‐warmed oocytes (Group III).

Results

The testicular sperm recovery rate was 57.8% (463/801): 89.6% in the Crypt, 97.1% in the OA, 28.9% in the NOA, and 42.2% in the KS groups. The follicle‐stimulating hormone levels were significantly higher in the NOA and KS groups and the testosterone levels were significantly lower in the KS group. The FR, PR, and BR were: 65.2%, 43.2%, and 28.5% in group I; 59.2%, 33.4%, and 18.7% in group II; and 56.4%, 33.8%, and 22.1% in group III.

Conclusion

Intracytoplasmic sperm injection with FS‐FO achieved the best PR and BR. It should be considered what to do in cases with no testicular sperm by TESE. The authors hope that ICSI with donor sperm will be allowed in Japan in the near future.

Seminal plasma antioxidants are directly involved in boar sperm cryotolerance

Boar ejaculates are ejected in fractions with a specific composition in terms of sperm numbers and seminal plasma (SP), which is reflected in the varying sperm cryotolerance observed among different fractions. As boar sperm are particularly sensitive to oxidative stress, this study evaluated the role of SP antioxidants in the observed differences in sperm cryotolerance among ejaculate fractions. Ten ejaculates from five boars were manually collected in fractions: the first 10 mL of the sperm-rich fraction (SRF), the rest of the SRF and the post-SRF. Semen samples comprising the entire ejaculate (EE) were created by proportionally mixing the three fractions described above. Each of the 40 resulting semen samples was split into two aliquots: one was used for sperm cryopreservation following a standard protocol utilizing 0.5-mL straws, and the other was used to collect SP for antioxidant assessment. Frozen-thawed (FT) sperm from the SRF (the first 10 mL of the SRF and the rest of the SRF) and those from post-SRF were of the highest and worst quality, respectively, which was measured in terms of total and objective progressive motility and viability (P < 0.01). Viable FT sperm from the post-SRF generated more reactive oxygen species and experienced more lipid peroxidation than those from the SRF (both the first 10 mL and the rest of the SRF) (P < 0.01). The percentage of FT sperm exhibiting fragmented nuclear DNA did not differ among ejaculate fractions and the EE. Catalase, glutathione peroxidase and glutathione peroxidase 5 (GPx-5) were lowest in SP from the first 10 mL of the SRF (P < 0.001), whereas superoxide dismutase (SOD) and paraoxonase 1 (PON-1) were highest in SP of the SRF (both the first 10 mL and the rest of the SRF) (P < 0.01). Trolox-equivalent antioxidant capacity (TEAC) and the ferric-reducing ability of plasma (FRAP) were highest in SP from the first 10 mL of the SRF and lowest in the post-SRF (P < 0.001), whereas cupric-reducing antioxidant capacity was lowest (P < 0.05) in SP from the first 10 mL of the SRF. Regression analyses indicated that certain SP antioxidants had good predictive value for post-thaw recovery rates of total motility (R² = 54.8%, P < 0.001; including SOD, TEAC and FRAP) and viability (R² = 56.1%, P < 0.001; including SOD, PON-1, GPx-5 and TEAC). These results demonstrated that certain SP antioxidants are positively involved in boar sperm cryotolerance, minimizing the oxidative stress imposed by cryogenic handling.

New approach to assess sperm DNA fragmentation dynamics: Fine-tuning mathematical models

Background

Sperm DNA fragmentation (sDF) has been proved to be an important parameter in order to predict in vitro the potential fertility of a semen sample. Colloid centrifugation could be a suitable technique to select those donkey sperm more resistant to DNA fragmentation after thawing. Previous studies have shown that to elucidate the latent damage of the DNA molecule, sDF should be assessed dynamically, where the rate of fragmentation between treatments indicates how resistant the DNA is to iatrogenic damage. The rate of fragmentation is calculated using the slope of a linear regression equation. However, it has not been studied if sDF dynamics fit this model. The objectives of this study were to evaluate the effect of different after-thawing centrifugation protocols on sperm DNA fragmentation and elucidate the most accurate mathematical model (linear regression, exponential or polynomial) for DNA fragmentation over time in frozen-thawed donkey semen.

Results

After submitting post-thaw semen samples to no centrifugation (UDC), sperm washing (SW) or single layer centrifugation (SLC) protocols, sDF values after 6 h of incubation were significantly lower in SLC samples than in SW or UDC. Coefficient of determination (R²) values were significantly higher for a second order polynomial model than for linear or exponential. The highest values for acceleration of fragmentation (aSDF) were obtained for SW, followed by SLC and UDC.

Conclusion

SLC after thawing seems to preserve longer DNA longevity in comparison to UDC and SW. Moreover, the fine-tuning of models has shown that sDF dynamics in frozen-thawed donkey semen fit a second order polynomial model, which implies that fragmentation rate is not constant and fragmentation acceleration must be taken into account to elucidate hidden damage in the DNA molecule.

Minimal volume vitrification of epididymal spermatozoa results in successful in vitro fertilization and embryo development in mice

This study compared three cryopreservation protocols on sperm functions, IVF outcomes, and embryo development. Epididymal spermatozoa cryopreserved using slow-cooling (18% w/v raffinose, RS-C) were compared with spermatozoa vitrified using 0.25 M sucrose (SV) or 18% w/v raffinose (RV). The motility, vitality, and DNA damage (TUNEL assay) of fresh control (FC) spermatozoa were compared with post-thawed or warmed RS-C, RV, and SV samples. Mouse oocytes (n = 267) were randomly assigned into three groups for insemination: RV (n = 102), RS-C (n = 86), and FC (n = 79). The number and the proportion of two-cell embryos and blastocysts from each treatment were assessed. Sperm motility (P < 0.01) and vitality (P < 0.05) were significantly reduced after vitrification compared with slow-cooled spermatozoa. However, DNA fragmentation was significantly reduced in spermatozoa vitrified using sucrose (15 ± 1.8% [SV] vs 26 ± 2.8% [RV] and 27 ± 1.2% [RS-C]; P < 0.01). Although the number of two-cell embryos produced by RS-C, RV, and FC spermatozoa was not significantly different, the number of blastocysts produced from two-cell embryos using RV spermatozoa was significantly higher than FC spermatozoa (P = 0.0053). This simple, small volume vitrification protocol and standard insemination method allows successful embryo production from small numbers of epididymal spermatozoa and may be applied clinically to circumvent the need for ICSI, which has the disadvantage of bypassing sperm selection.

Decreased activity of superoxide dismutase in the seminal plasma of infertile men correlates with increased sperm deoxyribonucleic acid fragmentation during the first hours after sperm donation

Sperm DNA fragmentation varies between individuals and is more pronounced with increased patient age and time after sperm donation. The intensification of DNA fragmentation depends on the balance of the oxidoreductive system, which is regulated mainly by two enzymes - superoxide dismutase (SOD) and catalase. The objective of this study was to determine the relationship between sperm DNA fragmentation dynamics, fertility and seminal SOD and catalase activity. The study was conducted in 2013 and 2014 at the Non-Public Health Care Unit 'Ovum Reproduction and Andrology' in Lublin, Lublin, Poland, and covered 218 men aged 25-35 (85 fertile and 133 patients treated for infertility). Percentage of fragmented DNA was measured in a modified chromatin dispersion test at four time points after sperm donation (t = 0, 3, 6, 12 h). SOD and catalase activities were determined spectrophotometrically. We confirmed that the activity of SOD in the seminal plasma of men with reproductive disorders was lower compared with fertile men. Conversely, no significant correlations were found between fertility and catalase activity. Sperm DNA of infertile males was initially more fragmented than fertile male sperm DNA. SOD and catalase activity did not correlate with the degree of DNA fragmentation in fertile men. In men with reproductive disorders, the rate of DNA fragmentation was slow within first 3 h after sperm donation and then increased between 6 and 12 h. In this group of infertile men, those with higher SOD activity had a lower DNA fragmentation index (DFI) after 12 h, and a reduced rate of intensity of fragmentation from 6 to 12 h. Alternatively, higher catalase activity among men treated for infertility was accompanied by higher initial DFI and higher rate of DNA fragmentation from 6 to 12 h. These results highlight the importance of determining a proper time window between sperm donation and procedures of assisted reproductive technology.

The effect of two cryopreservation methods on human sperm DNA damage

Several methods are currently available for selection when conducting sperm cryopreservation, however, these methods might cause different degrees of damage on sperm DNA. The aim of the this study is to compare the effects of storage at -80 °C (in ultra-low temperature refrigerator) and at -196 °C (in liquid nitrogen) on sperm DNA damage, thus to provide a reference for choosing the right method according to different aims. We randomly collected 28 semen samples from college students of Chongqing city. The samples stored at -80 °C were neat semen samples and the samples stored at -196 °C were mixed with additional cryoprotectants. Each sample was subjected to two freezing-thawing cycles, and the sperm DNA damage levels of fresh and thawed samples were measured by single cell gel electrophoresis (SCGE) and sperm chromatin structure assay (SCSA). Both SCGE and SCSA assays showed cryopreservation induced significant damage to sperm DNA. However, storage at -196 °C lead to more severe damage to sperm DNA than storage at -80 °C measured by SCSA. Sperm DNA damage increased simultaneously with the higher frequency of freezing-thawing cycles. We concluded that storage of neat semen samples at -80 °C had milder damage to sperm DNA than storage at -196 °C mixed with cryoprotectants. To avoid additional sperm DNA damage, repeated freezing and thawing should be prevented.

Advances in reproductive biotechnologies

In recent times, reproductive biotechnologies have emerged and started to replace the conventional techniques. It is noteworthy that for sustained livestock productivity, it is imperative to start using these techniques for facing the increasing challenges for productivity, reproduction and health with impending environment conditions. These recent biotechniques, both in male and female, have revolutionized and opened avenues for studying and manipulating the reproductive process both in vitro and in vivo in various livestock species for improving tis efficiency. This review attempts to highlight pros and cons, on the recent developments in reproductive biotechnologies, both in male and female in livestock species.

Unpacking the mysteries of sperm DNA fragmentation

Although it has been thirty years since publication of one of the most influential papers on the value of assessing sperm DNA damage, andrologists have yet to reach a general consensus about how to apply this seminal parameter to improve or predict reproductive outcomes. Studies that have attempted to establish a causal relationship between sperm DNA damage and pregnancy success have often resulted in conflicting findings, eroding the practitioner’s confidence to incorporate this phenomenon into their appraisal of fertility. In this review we have identified and answered ten important unresolved questions commonly asked by andrologists with respect to the relationship between sperm DNA damage and fertility. We answer questions ranging from a basic comprehension of biological mechanisms and external factors that contribute to increased levels of sperm DNA damage in the ejaculate to what type of DNA lesions we might be expect to occur and what are some of the consequences of DNA damage on early embryonic development. We also address some of the fundamental technical issues associated with the most appropriate measurement of sperm DNA damage and the need to attenuate the confounding impacts of iatrogenic damage. We conclude by asking whether it is possible to reduce elevated levels of sperm DNA damage therapeutically.

Relationship between pregnancy, embryo development, and sperm deoxyribonucleic acid fragmentation dynamics

The way the dynamics of DNA fragmentation affects the growth of embryos in real time, and effectiveness of infertility treatment using the ICSI procedure were determined in 148 couples treated with the ICSI technique. The percentage of sperm with fragmented DNA (known as the DNA fragmentation index [DFI]) in semen samples was determined at 3, 6 and 12 h. Embryo culture was assessed continuously during 12 h of observation monitoring.

Statistically significant difference was found in DFI at 12 h and outcome of treatment. For the remaining time intervals, no statistically significant differences were noted. An analysis of relationship between the DFI dynamics over time at individual measurements and achievement of pregnancy, confirmed a statistically significant relationship between the rate measured at 6–12 h of observations of DFI changes (DFI 12 h%/h), and achieving pregnancy. Correlation was observed between DFI (during 0, 3, 6 and 12 h), the growth rate in DFI, and time of embryo development. A statistically significant relationship was found between the rate from the start to the end of observations of the DFI, and outcome of treatment.

Intensity level regarding fragmentation of sperm DNA and its growth rate affected the time of embryo development in the ICSI procedure. The most significant prognostic factor for achieving pregnancy was intensification of sperm DNA fragmentation after 12 h.

Urinary concentrations of benzophenone-type ultraviolet light filters and semen quality

OBJECTIVE

To assess benzophenone-type ultraviolet (UV) filter concentrations, chemicals used in sunscreen and personal care products, and semen endpoints.

DESIGN

Cohort.

SETTING

Not applicable.

PATIENT(S)

A total of 413 men provided semen and urine samples, 2005-2009. Five UV filters were quantified (ng/mL) in urine using liquid chromatography-triple quadrupole mass spectrometry: BP-1 (2,4-dihydroxybenzophenone), BP-2 (2,2',4,4'-tetrahydroxybenzophenone), BP-3 (2-hydroxy-4-methoxybenzophenone), BP-8 (2,2'-dihydroxy-4-methoxybenzophenone), and 4-OH-BP (4-hydroxybenzophenone). Using linear regression, β-coefficients (β) and 95% confidence intervals (CIs) for each chemical dichotomized at the 75th percentile and Box-Cox transformed semen endpoint were estimated, after adjusting for age, body mass index, cotinine, season, and site.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Thirty-five semen endpoints.

RESULT(S)

BP-2 was associated with diminished sperm concentration (β = -0.74; 95% CI -1.41, -0.08), straight (β = -4.57; 95% CI -8.95, -0.18) and linear movement (β = -3.15; 95% CI -6.01, -0.30), more immature sperm (β = 0.38; 95% CI 0.15, 0.62), and a decreased percentage of other tail abnormalities (β = -0.16; 95% CI -0.31, -0.01). BP-8 was associated with decreased hypo-osmotic swelling (β = -2.57; 95% CI -4.86, -0.29) and higher acrosome area (β = 1.14; 95% CI 0.01, 2.26). No associations were observed for BP-1, BP-3, or 4OH-BP.

CONCLUSION(S)

The findings suggest that specific UV filters may be associated with some aspects of semen endpoints, but await future corroboration.

In vitro incubation of human spermatozoa promotes reactive oxygen species generation and DNA fragmentation

The aim of this study was to investigate the oxidative process associated with sperm capacitation and its impact on DNA fragmentation and sperm function. Redox activity and lipid peroxidation were analysed in human spermatozoa after 3, 6 and 22 h of incubation in Ham's F10 medium plus bovine albumin at 37° and 5% CO2 for capacitation. DNA status, tyrosine phosphorylation pattern and induced acrosome reaction were evaluated after capacitating conditions. At 22 h of incubation, there was a significant (P < 0.05) increase in oxygen-free radicals and lipid peroxidation, with no effect on sperm viability. There also was a significant (P < 0.001) increase in fragmented DNA in capacitated spermatozoa compared to semen values with higher rates being found after the occurrence of the induced acrosome reaction. Protein tyrosine phosphorylation pattern confirms that capacitation took place in parallel with the occurrence of DNA fragmentation. These results indicate that when spermatozoa are incubated for several hours (22 h), a common practice in assisted reproductive techniques, an increase in oxidative sperm metabolism and in the proportion of fragmented DNA should be expected. However, there was no effect on any of the other functional parameters associated with sperm fertilising capacity.

A translational medicine appraisal of specialized andrology testing in unexplained male infertility

The diagnostic and prognostic validity of sperm function biomarkers is particularly relevant for males with unexplained infertility in which routine semen analysis fails to detect subcellular sperm dysfunctions. In this general review, we examine the role and significance of specialized andrology laboratory tests from past to present and provide a glance toward the future. We concluded that the assessment of sperm DNA damage and oxidative stress provide a relatively independent measure of fertility that yields diagnostic and prognostic information complementary to, but distinct and more significant than, standard sperm parameters. Since none of the available methods for such testing have been fully translated, further research is necessary to evaluate their cost-effectiveness when applied in large scale to daily medical practice. Application of translational medicine concepts would also be useful to accelerate the clinical application of recent discoveries in the fields of genomics, proteomics and metabolomics.

Assessment of sperm function parameters and DNA fragmentation in ejaculated alpaca sperm (Lama pacos) by flow cytometry

Flow cytometry has been shown to be an accurate and highly reproducible tool for the analysis of sperm function. The main objective of this study was to assess sperm function parameters in ejaculated alpaca sperm by flow cytometry. Semen samples were collected from six alpaca males and processed for flow cytometric analysis of sperm viability and plasma membrane integrity using SYBR-14⁄PI staining; acrosomal membrane integrity using FITC-conjugated Pisum Sativum Agglutinin⁄PI labelling; mitochondrial membrane potential (Δψm) by staining with JC-1 and DNA Fragmentation Index (DFI) by TUNEL. The results indicate that the mean value for sperm viability was 57 ± 8 %. Spermatozoa with intact acrosome membrane was 87.9 ± 5%, and viable sperm with intact acrosomal membrane was 46.8 ± 9%, high mitochondrial membrane potential (Δψm) was detected in 66.32 ± 9.51% of spermatozoa and mean DFI value was 0.91 ± 0.9%. The DFI was inversely correlated with high Δψm (p = 0.04; r = -0.41) and with plasma membrane integrity (p = 0.01; r = -0.47). To our knowledge, this is the first report of the assessment on the same sample of several parameters of sperm function in ejaculated alpaca sperm by flow cytometry.