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

Sperm chromatin dispersion assay reliability and assisted reproductive technology outcomes: Systematic review and meta-analysis

OBJECTIVE

Elevated sperm DNA fragmentation has potential implications for semen quality and fertility. The commonly used sperm chromatin dispersion test offers an indirect estimation but has limitations in terms of bias and variability. This study aimed to assess the reliability of the sperm chromatin dispersion assay for predicting assisted reproductive technology outcomes.

MATERIALS AND METHODS

This systematic review included studies published until December 2023 that adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed/MEDLINE, Scopus, and Google Scholar databases were searched. Various assisted reproductive technology outcomes in patients with high (≥ 30%) versus low (< 30%) sperm DNA fragmentation were compared using a sperm chromatin dispersion assay and including a sub-analysis of intracytoplasmic sperm injection versus in vitro fertilization. A comprehensive meta-analysis software facilitated quantitative analysis with statistical comparisons between cases and controls. Interstudy heterogeneity was assessed, and sensitivity and publication bias tests were performed.

RESULTS

Of the 199 abstracts assessed, 64 full-text articles were screened, and 44 articles were qualitatively synthesized. Fourteen articles representing 5346 participants were quantitatively analyzed. Using the sperm chromatin dispersion assay, elevated sperm DNA fragmentation was associated with lower fertilization and embryo cleavage rates. Notably, high sperm DNA fragmentation levels did not affect the clinical pregnancy, implantation, miscarriage, or live birth outcomes. Sub-analysis revealed lower fertilization, embryo cleavage, clinical pregnancy, live birth rates, and higher miscarriage rates in the intracytoplasmic sperm injection subgroup only.

CONCLUSIONS

The sperm chromatin dispersion assay did not show significant differences in pregnancy or live birth rates between the high- and low-sperm DNA fragmentation groups. Noteworthy, high sperm DNA fragmentation was associated with worse assisted reproductive technology outcomes in the intracytoplasmic sperm injection group. Given the current quality of the evidence, affected by the experimental design and the absence of correction for female factors of infertility, clinicians should be wary of the assay's limited predictive power for pregnancy and live birth outcomes.

A novel biosensor for highly sensitive DNA damage detection using TdT and CRISPR-Cas12a

This study presents a highly sensitive fluorescence biosensor integrating TdT enzyme and CRISPR-Cas12a for precise detection of sperm DNA damage, achieving a detection limit of 0.99 pM and a linear range of 0.001-0.2 nM. Its exceptional sensitivity, simplicity, and versatility make it a transformative tool for reproductive medicine and clinical diagnostics.

Emerging trends in sperm selection: enhancing success rates in assisted reproduction

This comprehensive review explores the evolving landscape of sperm selection techniques within the realm of Assisted Reproductive Technology (ART). Our analysis delves into a range of methods from traditional approaches like density gradient centrifugation to advanced techniques such as Magnetic-Activated Cell Sorting (MACS) and Intracytoplasmic Morphologically Selected Sperm Injection (IMSI). We critically assess the efficacy of these methods in terms of sperm motility, morphology, DNA integrity, and other functional attributes, providing a detailed comparison of their clinical outcomes. We highlight the transition from conventional sperm selection methods, which primarily focus on physical characteristics, to more sophisticated techniques that offer a comprehensive evaluation of sperm molecular properties. This shift not only promises enhanced prediction of fertilization success but also has significant implications for improving embryo quality and increasing the chances of live birth. By synthesizing various studies and research papers, we present an in-depth analysis of the predictability of different sperm selection procedures in ART. The review also discusses the clinical applicability of these methods, emphasizing their potential in shaping the future of assisted reproduction. Our findings suggest that the integration of advanced sperm selection strategies in ART could lead to more cost-effective treatments with reduced duration and higher success rates. This review aims to provide clinicians and researchers in reproductive medicine with comprehensive insights into the current state and future prospects of sperm selection technologies in ART.

New insights into semen separation techniques in buffaloes

Male infertility is frequently caused by idiopathic or unexplained reasons, resulting in an increase in demand for assisted reproductive technologies. In buffaloes, more than in other animals due to reproductive hardiness, successful fertilization needs spermatozoa to effectively transit the female reproductive system to reach the oocyte. This mechanism naturally picks high-quality sperm cells for conception, but when artificial reproductive technologies such as in vitro fertilization, intracytoplasmic sperm injection, or intrauterine insemination are utilized, alternative techniques of sperm selection are necessary. Currently, technology allows for sperm sorting based on motility, maturity, the lack of apoptotic components, proper morphology, and even sex. This study provides current knowledge on all known techniques of sperm cell sorting in buffaloes, evaluates their efficiency, and discusses the benefits and drawbacks of each approach.

Controversy and Consensus on the Management of Elevated Sperm DNA Fragmentation in Male Infertility: A Global Survey, Current Guidelines, and Expert Recommendations

PURPOSE

Sperm DNA fragmentation (SDF) has been associated with male infertility and poor outcomes of assisted reproductive technology (ART). The purpose of this study was to investigate global practices related to the management of elevated SDF in infertile men, summarize the relevant professional society recommendations, and provide expert recommendations for managing this condition.

MATERIALS AND METHODS

An online global survey on clinical practices related to SDF was disseminated to reproductive clinicians, according to the CHERRIES checklist criteria. Management protocols for various conditions associated with SDF were captured and compared to the relevant recommendations in professional society guidelines and the appropriate available evidence. Expert recommendations and consensus on the management of infertile men with elevated SDF were then formulated and adapted using the Delphi method.

RESULTS

A total of 436 experts from 55 different countries submitted responses. As an initial approach, 79.1% of reproductive experts recommend lifestyle modifications for infertile men with elevated SDF, and 76.9% prescribe empiric antioxidants. Regarding antioxidant duration, 39.3% recommend 4-6 months and 38.1% recommend 3 months. For men with unexplained or idiopathic infertility, and couples experiencing recurrent miscarriages associated with elevated SDF, most respondents refer to ART 6 months after failure of conservative and empiric medical management. Infertile men with clinical varicocele, normal conventional semen parameters, and elevated SDF are offered varicocele repair immediately after diagnosis by 31.4%, and after failure of antioxidants and conservative measures by 40.9%. Sperm selection techniques and testicular sperm extraction are also management options for couples undergoing ART. For most questions, heterogenous practices were demonstrated.

CONCLUSIONS

This paper presents the results of a large global survey on the management of infertile men with elevated SDF and reveals a lack of consensus among clinicians. Furthermore, it demonstrates the scarcity of professional society guidelines in this regard and attempts to highlight the relevant evidence. Expert recommendations are proposed to help guide clinicians.

Correlation analysis of sperm DNA fragmentation index with semen parameters and the effect of sperm DFI on outcomes of ART

Routine semen analysis provides limited information about a man's male reproductive potential and can not always fully explain male infertility. Many male infertilities are caused by sperm DNA defects that routine semen quality analyses fail to detect. In this study, we analyzed the association of sperm DNA fragmentation index (DFI) with the semen routine, sperm morphology, in vitro fertilization embryo transfer (IVF-ET)/intracytoplasmic sperm injection (ICSI). Further, we explored the predictive value of sperm DFI in evaluating male fertility and the outcome of IVF-ET/ICSI. Data on sperm DFI, sperm routine, and sperm morphology were collected from 1462 males with infertility. According to DFI levels, there were 468 cases in group I (DFI ≤ 15%), 518 cases in group II (15% < DFI < 30%), and 476 cases in group III (DFI ≥ 30%). The correlations of sperm DFI with semen routine and malformation rate were analyzed. Seminal plasma malondialdehyde (MDA), and total antioxidant capacity (TAC) were assessed. Sperm DFI, semen routine, and sperm morphology were detected in male patients of 101 pairs of IVF-ET/ICSI infertile couples and subdivided into IVF-I group (DFI ≤ 15%), IVF-II group (15% < DFI < 30%), IVF-III group (DFI ≥ 30%), ICSI-I group (DFI ≤ 15%), ICSI-II group (15% < DFI < 30%) and ICSI-III group (DFI ≥ 30%) according to DFI value. The effect of sperm DFI on the outcome of IVF-ET/ICSI was analyzed. There were significant differences in sperm survival rate, sperm concentration, and PR% between groupIII and group II (P < 0.01). There were significant differences in sperm survival rate, sperm concentration and PR% between group III and group I (P < 0.01). There was no significant difference in semen volume, age, abstinence days, or percentage of normal sperm between the three groups (P > 0.05). DFI was positively correlated with MDA content ( P < 0.01) and negatively correlated with TAC (P < 0.01). Sperm DFI was negatively correlated with sperm survival rate, sperm concentration, and PR% (P < 0.01). There was no correlation with age, abstinence days, semen volume, or percentage of normal-form sperm (r = 0.16, 0.05, 0.04, -0.18, p > 0.05). Compared with IVF-I group, the sperm concentration and PR were decreased in IVF-III group. The sperm malformation rate was higher in IVF-III group than that in IVF-II group. Comparatively, the PR was decreased in ICSI-III group. The sperm malformation rate was higher in ICSI-III group than that of the ICSI-I group (P < 0.05). There were no statistically significant differences in fertilization rate, cleavage rate, embryo rate, and clinical pregnancy rate between IVF group or ICSI group, and between all subgroups (P > 0.05). Sperm DFI is negatively associated with sperm survival rate, sperm concentration, and PR%. Antioxidants can decrease the rate of DNA fragmentation. Sperm DFI has proven to be very valuable in the male fertility evaluation, but its significance as a predictor of pregnancy outcomes following assisted reproductive technology. (ART) requires further investigation.

The efficacy of novel centrifugation-free sperm selection (Io-Lix) on sperm parameters and ICSI reproductive outcomes

RESEARCH QUESTION

What is the effect of a novel non-centrifugation method (Io-Lix) of sperm selection on sperm parameters and intracytoplasmic sperm injection (ICSI) reproductive outcomes?

DESIGN

This pilot study elevated the capacity of the Io-Lix sperm selection protocol to improve sperm parameters (concentration, motility and sperm DNA fragmentation) of the neat ejaculate. Once established, the reproductive outcomes of Io-Lix selected spermatozoa were used for autologous and donor oocyte ICSI programmes and their efficacy compared with those using conventional swim-up.

RESULTS

Io-Lix sperm selection resulted in lower sperm concentration yield (P < 0.001) and sperm DNA fragmentation (P < 0.001) but higher sperm motility (P < 0.001) when compared with spermatozoa in the neat ejaculate. When compared with swim-up sperm selection the Io-Lix protocol resulted in a 14.7% (P = 0.028) increase in pregnancy rate and 16.3% (P = 0.047) reduction in miscarriages in the autologous ICSI programme. A similar comparison of sperm selection procedures employed for a donor oocyte ICSI programme showed no difference in terms of their respective reproductive outcomes.

CONCLUSIONS

The Io-Lix sperm selection protocol resulted in improved pregnancy rate and reduction in miscarriage when applied to autologous ICSI, which was attributed to a reduction in the proportion of spermatozoa with DNA damage post-selection. A similar finding was not apparent in the donor oocyte programme, which may be associated with the capacity of the donor oocyte to repair sperm DNA post-syngamy.

Efficacy of density gradient centrifugation technique (DGC) in enhancing sperm cell DNA quality for assisted reproductive technique

Objective

Density gradient centrifugation (DGC) is commonly used for sperm preparation before assisted reproductive technology (ART) procedures. This technique separates superior motile spermatozoa with normal morphology from the total sperm population. However, there is still controversy as to the effects of this sperm separation technique on sperm cell DNA integrity which is a determining element in the process of fertilization and embryonic development.

The objective of this study was to determine the effects of DGC on sperm cell DNA integrity as assessed by a novel association between two cytogenetic tests.

Study designs

Semen samples were collected from 30 fertile donors and 40 patients being candidates for ART treatment. Each sample was divided into two parts: the first portion was subjected to selection by two layers of DGC (45% and 90%) and the second fraction was rinsed with phosphate-buffered saline solution and centrifuged without density gradient.

Abnormal sperm chromatin structure as evaluated by a sperm chromatin dispersion (SCD) test and DNA denaturation as assessed by an acridine orange (AO) test were monitored in the initially washed sample and in the different layers of the density gradient centrifugation.

Results

DGC significantly improved the proportion of sperm progressive motility, total motility, and sperm morphology. Moreover, following density gradient centrifugation, the proportion of spermatozoa with denaturated DNA significantly decreased when compared with whole semen (p < 0.001). In addition, we found that spermatozoa isolated in the 90% layer possessed a significantly lower percentage of sperm chromatin decondensation when compared with those remaining in the 45% layer and unprocessed semen (p < 0.001).

Conclusions

Using double cytogenetic tests, our study shows that semen processing by density gradient centrifugation is useful in selecting sperm with higher double-strand DNA integrity and recommended to be used in sperm preparation for assisted reproduction.

Effects of sperm preparation techniques on sperm survivability and DNA fragmentation

OBJECTIVE

This study was performed to determine the effect of swim-up (SU) and density gradient centrifugation (DGC) on sperm survival and DNA fragmentation.

METHODS

Individual semen samples were analyzed before each was divided into two aliquots (half for SU and half for DGC) for calculation of sperm survival and the DNA fragmentation index (DFI). Sperm DNA fragmentation was determined using the sperm chromatin dispersion test.

RESULTS

The DFI of the 63 semen samples processed using both procedures was lower than that of the fresh semen samples. The DFI was significantly lower for samples processed using the SU than DGC method. In the sperm survival test, the SU technique was associated with increased sperm motility and vitality following preparation. After 24 hours, however, the concentration and percentage of surviving sperm were significantly lower in the SU than DGC group.

CONCLUSIONS

Both semen preparation techniques help to minimize sperm DNA fragmentation; however, when the DFI is <30%, the SU technique is more appropriate than DGC. While DGC may be superior for intrauterine insemination, the SU method may be preferable for in vitro fertilization or maturation.

Sperm morphology and DNA fragmentation after zona pellucida selection

Sperm DNA fragmentation (SDF) and sperm morphological defects can negatively affect ART outcomes. Consequently, there is a need for additional semen processing technique that accounts for sperm DNA status and morphology prior to ICSI. The objective was to evaluate the efficacy of an additional zona pellucida adhesion-based sperm selection for obtaining sperm populations with a high percentage of normal morphology and DNA integrity as compared to native semen and routine swim-up preparation. Semen samples from 78 normozoospermic men were subjected to swim up and placed in petri dishes coated with 48 acid-solubilized zonae pellucidae. Sperm DNA fragmentation and morphology were assessed in the native semen, the swim-up samples, and the zona-adhered spermatozoa from each patient. The mean sperm DNA fragmentation of the zona-selected spermatozoa (3.5 ± 0.7%) was significantly lower than the swim-up samples (15.3 ± 5.2%) (P  < 0.001) and native semen (24.9 ± 7.1%) (P  < 0.001). All of the samples had lower levels of DNA damage after additional selection by zona pellucida adhesion. Significantly higher percentage of sperm with normal morphology was observed after zona-adhesion selection (11.4 ± 3.9%) when compared to the swim-up samples (8.9 ± 4.3%) (P  < 0.001) or the native semen (5.3 ± 3.2%) (P  < 0.001). In 94% of the samples, the percentage of spermatozoa with normal morphology increased after the additional zona selection. This study demonstrates that sperm selection by additional zona-adhesion technique yields a significantly higher percentage of spermatozoa with normal morphology as well as a significantly decreased level of DNA fragmentation when compared to the native semen and the swim-up-only prepared samples.

LAY SUMMARY

High level of DNA folding known as sperm DNA fragmentation (SDF) inside each sperm and defects in the shape, size, and structure of the sperm can negatively affect assisted reproduction treatment (ART) outcomes. Consequently, there is a need for additional semen processing techniques that account for sperm quality prior to ART. Our team designed a simple technique using proteins from the coat around the egg (zona pellucida) to enhance sperm selection procedures based on natural sperm-egg interactions. Using this technique in combination with the most common techniques used in ART yields a significantly higher percentage of sperm with normal shape, size, and structure and a decreased level of DNA fragmentation. This sperm zona-selection technique would be beneficial if introduced in the ART practice to yield sperm with higher fertilization potential.

Effect and mechanisms of reproductive tract infection on oxidative stress parameters, sperm DNA fragmentation, and semen quality in infertile males

Recent years have seen a rising incidence of male infertility, mostly caused by the decline of sperm quality. The ratio of infertile males to infertile females has escalated from 3:7 in 2013 to current 5:5, which turns male infertility into the research focus of reproductive medicine. This study aimed to clarify the effect of reproductive tract infection by ureaplasma urealyticum (UU) and chlamydia trachomatis (CT) on the DNA integrity and routine semen parameters of infertile males. A retrospective study was performed. A total of 259 infertile males who were treated at the Andrological Laboratory Examination and Reproductive Medicine Center in our hospital were analyzed. qRT-PCR was used to examine the infection status of CT and UU. According to the eligibility criteria, we evaluated the semen parameters and biochemical data of 253 men. Based on the results of PCR, the subjects were divided into four groups: Group I (CT positive, 63 cases), Group II (UU positive, 60 cases), Group III (CT positive and UU positive, 62 cases), and Group IV (no infection, 68 cases). DNA fragmentation index (DFI), sperm count, vitality and morphology, elastase level, seminal plasma malondialdehyde (MDA), and total antioxidant capacity (TAC) were assessed. Compared to Group IV, three groups (Group I, Group II and Group III) showed difference in semen volume, proportion of sperm with normal morphology, sperm motility, progressive motility, and vitality (P < 0.05). Compared to Group IV, Group II and Group III showed difference in DFI (P < 0.05). Compared to Group IV, Group II and Group III showed difference in elastase level (P < 0.05). VCL, VSL, VAP, WOB, ROS, TM, HDS showed differences between groups of abnormal/normal WBC (*P < 0.01).UU infection significantly increased the level of seminal leukocytes only in Group II, but not in the other three groups, indicating that UU is a factor to increase the level of seminal leukocytes. Compared with the normal leukocyte group, there were significant differences in total motility, forward motility and normal sperm ratio between the two groups. The proportion of sperm with abnormal morphology (mostly in the head) showed obvious difference between groups of high and normal seminal leukocytic levels. At the same time, in this study, SCGE and SCD verified that leukocytes could damage sperm DNA by increasing ROS, which ultimately affects male fertility.

Effect of macrophages in semen on sperm quality

BACKGROUND

This was a cross-sectional study in China which analyzed the levels of macrophages (Mφ) in semen and evaluated the influence of Mφ levels in semen on sperm quality.

METHODS

The subjects involves 78 males, 25- to 35-year old. The samples were divided into a low group (Mφ < 6 × 105/ml) and a high group (Mφ > 6 × 105/ml). Evaluation included consideration of the influencing factors of male semen quality, macrophage concentration, sperm motility, morphology, membrane integrity DNA fragmentation index (DFI), anti-sperm antibodies (AsAb), IL-10, and IL-12 in semen.

RESULTS

There was no difference in the physical or chemical indices of the semen, sperm concentration, AsAb, IL-10, or IL-12 between the two groups (P > 0.05). The percentage of sperm forward motility (PR%), the rate of normal sperm shape, and the integrity of cell membranes in the low group were higher than those in the high group (P < 0.05), while the percentage of sperm inactivity (IM%), the rate of sperm head deformity, the rate of deformity in the neck and middle segment, the sperm deformity index (SDI), the teratozoospermia index (TZI), and the sperm DFI in the low group were lower than those in the high group (P < 0.05). The concentration of Mφ in the semen was linearly correlated with sperm concentration, sperm PR%, IM%, sperm normal shape rate, head deformity rate, neck and middle deformity rate, SDI, TZI, sperm DFI, and sperm cell membrane integrity (P < 0.05), but there was no linear correlation with IL-10 or IL-12 (P > 0.05).

CONCLUSIONS

The Mφ concentration in semen is not significantly correlated with semen volume or sperm concentration, but negatively correlated with sperm motility, morphology, cell membrane integrity, and DNA damage rate. There is no significant correlation between the macrophages and the concentration of IL-10 or IL-12.

Clinical implications of sperm DNA damage in IVF and ICSI: updated systematic review and meta-analysis

The clinical effect of sperm DNA damage in assisted reproduction has been a controversial topic during recent decades, leading to a variety of clinical practice recommendations. While the latest European Society of Human Reproduction and Embryology (ESHRE) position report concluded that DNA damage negatively affects assisted reproduction outcomes, the Practice Committee of the American Society for Reproductive Medicine (ASRM) does not recommend the routine testing of DNA damage for in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Herein, our aim was to perform a systematic review and meta-analysis of studies investigating whether sperm DNA damage affects clinical outcomes in IVF and ICSI, in order to contribute objectively to a consistent clinical recommendation. A comprehensive systematic search was conducted according to PRISMA guidelines from the earliest available online indexing year until March 2020, using the MEDLINE-PubMed and EMBASE databases. We included studies analysing IVF and/or ICSI treatments performed in infertile couples in which sperm DNA damage was well defined and assessed. Studies also had to include information about pregnancy, implantation or live birth rates as primary outcomes. The NHLBI-NIH quality assessment tool was used to assess the quality of each study. Meta-analyses were conducted using the Mantel-Haenszel method with random-effects models to evaluate the Risk Ratio (RR) between high-DNA-damage and control groups, taking into account the 95% confidence intervals. Heterogeneity among studies was evaluated using the I² statistic. We also conducted sensitivity analyses and post-hoc subgroup analyses according to different DNA fragmentation assessment techniques. We identified 78 articles that met our inclusion and quality criteria and were included in the qualitative analysis, representing a total of 25639 IVF/ICSI cycles. Of these, 32 articles had sufficient data to be included in the meta-analysis, comprising 12380 IVF/ICSI cycles. Meta-analysis revealed that, considering IVF and ICSI results together, implantation rate (RR = 0.74; 95% CI = 0.61-0.91; I²  = 69) and pregnancy rate (RR = 0.83; 0.73-0.94; I²  = 58) are negatively influenced by sperm DNA damage, although after adjustment for publication bias the relationship for pregnancy rate was no longer significant. The results showed a non-significant but detrimental tendency (RR = 0.78; 0.58-1.06; I²  = 72) on live birth rate. Meta-analysis also showed that IVF outcomes are negatively influenced by sperm DNA damage, with a statistically significant impact on implantation (RR = 0.68; 0.52-0.89; I²  = 50) and pregnancy rates (RR = 0.72; 0.55-0.95; I²  = 72), although the latter was no longer significant after correction for publication bias. While it did not quite meet our threshold for significance, a negative trend was also observed for live birth rate (RR = 0.48; 0.22-1.02; I²  = 79). In the case of ICSI, non-significant trends were observed for implantation (RR = 0.79; 0.60-1.04; I²  = 72) or pregnancy rates (RR = 0.89; 0.78-1.02; I²  = 44), and live birth rate (RR = 0.92; 0.67-1.27; I²  = 70). The current review provides the largest evidence to date supporting a negative association between sperm DNA damage and conventional IVF treatments, significantly reducing implantation and pregnancy rates. The routine use of sperm DNA testing is therefore justified, since it may help improve the outcomes of IVF treatments and/or allow a given couple to be advised on the most suitable treatment. Further well-designed controlled studies on a larger number of patients are required to allow us to reach more precise conclusions, especially in the case of ICSI treatments.

A Simple, Centrifugation-Free, Sperm-Sorting Device Eliminates the Risks of Centrifugation in the Swim-Up Method While Maintaining Functional Competence and DNA Integrity of Selected Spermatozoa

This pilot study was conducted to explore the benefits of using a centrifugation-free device based on the migration–sedimentation (MS) technique over centrifugation-based techniques in selecting competent spermatozoa, as compared with using split human semen samples. Ejaculates from 35 men undergoing semen analysis were split into four parts where one part was retained as the neat (NE) and the other three parts were subjected to sperm selection by using migration–sedimentation (MS), density gradient (DG) separation, and swim-up (SU) techniques. Sperm functional characteristics along with mitochondrial integrity, tyrosine phosphorylation, acrosome reaction, and ultrastructure were measured. The ability of selection techniques in reducing spontaneous and radiation-induced sperm DNA lesions was assessed by the TUNEL assay. In results, MS-selected spermatozoa had higher viability (P < 0.001), longevity in terms of total motility at the end of 6 and 18 h post-extraction (P < 0.001), and mitochondrial integrity (P < 0.001) compared with those selected by DG. Furthermore, spontaneous DNA lesions were significantly reduced in MS and SU fractions compared with NE (P < 0.001). Similarly, radiation-induced sperm DNA lesions were significantly lower in MS and SU fractions (P < 0.001) compared with DG. Ultrastructural analysis using scanning electron microscopy suggested a moderate, non-significant increase in the number of spermatozoa with normal head and mid-piece in MS fraction compared with other methods. In conclusion, the MS-based device offers a centrifugation-free, efficient, and reliable sperm selection method, making it suitable for partially equipped intra-uterine insemination (IUI) laboratories or office IUI programmes. Further research should focus on the safety and clinical usefulness of the device in assisted conception programmes in general and IUI in specific.

Sperm selection strategies and their impact on assisted reproductive technology outcomes

The application of assisted reproductive technologies (ART) has revolutionised the treatment of human infertility, giving hope to the patients previously considered incapable of establishing pregnancy. While semen analysis is performed to access whether a sample has an adequate number of viable, motile and morphologically normal sperm cells able to achieve fertilisation, sperm selection techniques for ART aim to isolate the most competent spermatozoon which is characterised by the highest fertilising potential. Based on the semen analysis results, the correct sperm selection technique must be chosen and applied. In this review, different sperm selection strategies for retrieving spermatozoa with the highest fertilising potential and their impact on ART outcomes are discussed. In addition, advantages and disadvantages of each method and the best suited techniques for each clinical scenario are described.

Effects of the sperm DNA fragmentation index on the clinical and neonatal outcomes of intracytoplasmic sperm injection cycles

Background

Most studies have mainly focused on the effects of the sperm DNA fragmentation index (DFI) on fertilization, embryonic developmental potential and aneuploidy, pregnancy and abortion rates after in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) and have remained controversial. However, few studies have reported the effects of sperm DFI on neonatal outcomes, including stillbirths, neonatal deaths, sex, gestational age, prematurity, birthweight, low birth weight (LBW) and birth defects in newborns. Our objective was to evaluate the effects of sperm DFI on the clinical and neonatal outcomes of ICSI cycles.

Methods

This retrospective study analysed a total of 2067 oocyte retrieval, 1139 transfer and 713 delivery cycles from conventional ICSI cycles, including 301, 469, and 214 live-born infants in groups segregated according to sperm DFI as the < 15%, 15–30% and >  30% groups, respectively. The clinical and neonatal outcomes were compared among the three groups.

Results

Sperm DFI did not significantly affect the rates of fertilization, clinical pregnancy, miscarriage or ongoing pregnancy. Sperm DFI did not increase the risk of stillbirths or neonatal deaths. The rates of stillbirths and neonatal deaths were not significantly different among the three groups. The sex, gestational age, prematurity, birthweight and LBW of newborns in the three groups were not significantly affected by sperm DFI. Moreover, sperm DFI did not increase the number of birth defects in children.

Conclusions

Sperm DFI did not affect the clinical or neonatal outcomes of ICSI cycles.

Novel Techniques of Sperm Selection for Improving IVF and ICSI Outcomes

Almost 50% of the infertility cases are due to male factors. Assisted reproductive technologies (ARTs) allow to overcome the incapacity of these patients' spermatozoa to fertilize the oocyte and produce a viable and healthy offspring, but the efficiency of the different techniques has still the potential to improve. According to the latest reports of the European Society of Human Reproduction and Embryology (ESHRE) and the Centers for Disease Control and Prevention of the United States (CDC), the percentages of deliveries per ART cycle in 2014 and 2016 were 21 and 22%, respectively. Among the reasons for this relatively low efficiency, the quality of the spermatozoa has been pointed out as critical, and the presence of high percentages of DNA-damaged spermatozoa in patients' ejaculates is possibly one of the main factors reducing the ARTs outcomes. Thus, one of the main challenges in reproductive medicine is to ensure the highest quality of the spermatozoa used in ARTs, and specifically, in terms of genetic integrity. The latest techniques for the preparation and selection of human spermatozoa are herein discussed focusing on those proven to improve one or several of the following parameters: sperm genetic integrity, fertilization capacity, embryo production, and in vitro survival, as well as pregnancy and delivery rates following in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). In addition, we discuss the potential of techniques developed in non-human mammals that could be further transferred to the clinic.

Use of microfluidic sperm extraction chips as an alternative method in patients with recurrent in vitro fertilisation failure

PURPOSE

It is known that sperm preparation techniques in in vitro fertilisation (IVF) are intended to select the best-quality sperm. The aim of this study is to compare sperm the density gradient method and microfluidic chip (Fertile Plus) method in infertile patients by analysing fertilisation rates, pregnancy rates, and sperm morphology and DNA fragmentation rates posed by these two methods.

METHODS

Using semen samples obtained from the patients, sperms were prepared with gradient (n = 312) and microfluidic chip methods (n = 116). Fertilisation and pregnancy rates were compared in the first time and in the recurrent IVF trial patients. In addition, the morphology and DNA fragmentation comparison of sperm samples were evaluated by Toluidine blue in situ chemical staining method.

RESULTS

There was no statistically significant difference between fertilisation and pregnancy rates when compared with study groups in first-time IVF treatment patients. However, in recurrent IVF failure patients, there was a significant difference in fertilisation rates but no statistically significant difference was found in pregnancy rates. The microfluidic chip method significantly decreased sperm DNA fragmentation index according to density gradient method.

CONCLUSIONS

Microfluidic chip method may be recommended in patients with recurrent unsuccessful in vitro trials. The sperm DNA fragmentation test prior to the treatment will be helpful in selecting the appropriate sperm-washing method.

Sperm DNA fragmentation index influences assisted reproductive technology outcome: A systematic review and meta-analysis combined with a retrospective cohort study

Studies have explored the influence of DNA damage in assisted reproductive technology (ART), but the outcome remains controversial. To determine whether sperm DNA fragmentation index (DFI) has any effect on ART outcomes, we collected detailed data regarding 1,333 IVF cycles performed at our centre, and the data of our retrospective cohort study were extracted for this meta-analysis. We searched PubMed, Web of Science, EMBASE and Google Scholar and performed a systemic review and meta-analysis. Primary meta-analysis of 10 studies comprising 1,785 couples showed that live birth rate was no significantly different between low-DFI group and high-DFI group (p > 0.05). Secondary meta-analysis of 25 studies comprising 3,992 couples showed a higher miscarriage rate in high-DFI group than in low-DFI group (RR=1.57 [1.18, 2.09], p < 0.01). Meta-analysis of eight studies comprising 17,879 embryos revealed a lower good-quality embryo rate (RR=0.65 [0.62, 0.68], p < 0.01). Meta-analysis of 23 studies comprising 6,771 cycles showed that the high-DFI group had a lower clinical pregnancy rate than low-DFI group (RR=0.85 [0.75, 0.96], p < 0.01). Heterogeneity of included studies weakened our conclusions. Our study showed that DFI has adverse effects on ART outcome. More well-designed studies exploring the association between DFI and ART outcome are desired.

Evaluation of sperm DNA fragmentation using multiple methods: a comparison of their predictive power for male infertility

Objective

The usual seminal profile has been customarily used for diagnosing male infertility based on an examination of semen samples. However, sperm DNA fragmentation has also been causally linked to reproductive failure, suggesting that it should be evaluated as part of male infertility assessments. To compare the ability of the five most widely utilized methodologies of measuring DNA fragmentation to predict male infertility and reactive oxygen species by Oxisperm kit assay.

Methods

In this case-control study, which received ethical committee approval, the participants were divided into fertile and infertile groups (50 patients in each group).

Results

The alkaline comet test showed the best ability to predict male infertility, followed by the terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay, the sperm chromatin dispersion (SCD) test, and the sperm chromatin structure assay (SCSA), while the neutral comet test had no predictive power. For our patient population, the projected cut-off point for the DNA fragmentation index was 22.08% using the TUNEL assay, 19.90% using SCSA, 24.74% using the SCD test, 48.47% using the alkaline comet test, and 36.37% using the neutral comet test. Significant correlations were found between the results of the SCD test and those obtained using SCSA and TUNEL (r =0.70 and r =0.68, respectively; p<0.001), and a statistically significant correlation was also found between the results of SCSA and the TUNEL assay (r =0.77, p<0.001). Likewise, the results of the alkaline comet test showed significant correlations with those of the SCD, SCSA, and TUNEL tests (r =0.59, r =0.57, and r =0.72, respectively; p<0.001).

Conclusion

The TUNEL assay, SCSA, SCD, and the alkaline comet test were effective for distinguishing between fertile and infertile patients, and the alkaline comet test was the best predictor of male infertility.

An adapted carrier for the cryopreservation of human testicular spermatozoa

RESEARCH QUESTION

Does the adapted carrier Cryoplus improve the quality of cryopreserved spermatozoa compared with the use of conventional containers, and what is the effect of the adapted carrier on clinical outcomes?

DESIGN

Semen samples from 27 cases of oligozoospermia were used to investigate whether the adapted carrier improved cryopreserved sperm quality compared with the use of 0.25-ml straws and 2-ml cryogenic vials. Thirty testicular sperm samples were used to study the quality of testicular spermatozoa cryopreserved in the adapted carrier. The retrospective study included a further 104 men with azoospermia to investigate the clinical outcomes of testicular spermatozoa cryopreserved with the adapted carriers. Men with mostly obstructive azoospermia were included in this study.

RESULTS

The adapted carrier improved cryopreserved spermatozoa motility of semen samples compared with 2-ml cryogenic vials but not compared with 0.25-ml straws. No differences were found in cryopreserved sperm DNA fragmentation among the three carriers. Fertilization and good-quality embryo rates were similar in ICSI cycles using fresh or cryopreserved testicular spermatozoa. Additionally, no difference was evident between frozen-thawed embryo transfer cycles using fresh or cryopreserved testicular spermatozoa in clinical pregnancy, implantation, miscarriage, live birth rates or birth weight.

CONCLUSIONS

The adapted carrier improved the cryopreserved sperm motility compared with the effects of 2-ml cryogenic vials. The outcomes of intracytoplasmic sperm injection and frozen-thawed embryo transfer outcomes indicate that testicular spermatozoa cryopreserved using the adapted carrier is not inferior to fresh testicular spermatozoa. The use of the adapted carrier for cryopreserving human testicular spermatozoa especially from obstructive azoospermia is simple and effective.

Role of the Zeta Method in Intracytoplasmic Sperm Injection Outcomes in High Sperm DNA Fragmentation in Oligoasthenozoospermic Men

Background:

New methods are needed to optimize intracytoplasmic sperm injection (ICSI) outcomes in oligoasthenozoospermic (OAS) men. We evaluated the level of DNA fragment index (DFI) in OAS men and its impact on ICSI outcomes. In addition, we used the zeta potential method for sperm selection to investigate the efficacy of this technique in improving ICSI outcomes.

Materials and Methods:

This cross-sectional study was performed on 95 couples. Sperm parameters and sperm DNA fragmentation (SDF) were measured. The couples were divided into the following 3 groups: group I (n=30) where SDF was between 15% and 30%, and routine sperm was selected on the basis of motility and morphology; group II (n=34) where SDF was more than 30%, and the routine sperm selection method was applied on the basis of motility and morphology; and group III (n=31) where SDF was more than 30%, and the sperm selection was performed on the basis of the zeta method. The fertilization rate, embryo development, embryo quality, and implantation rate were evaluated in these 3 groups.

Results:

The fertilization rate was significantly higher in group I compared with group II (P<0.05). The embryo development rate in group I was significantly higher than that in group II (P<0.001) and group III (P<0.05), and it was significantly lower in group II compared with group III (P<0.05). The embryo quality was higher in group III compared with group II (P<0.01). The implantation rate in group I was significantly higher than that in group II (P<0.05) and group III (P<0.05).

Conclusions:

The present study indicated that a higher level of SDF has an adverse effect on the ICSI outcome. Furthermore, the zeta potential technique can be a useful method for sperm selection in OAS men.

Impact of sperm DNA fragmentation on clinical in vitro fertilization outcomes

Objective

We studied the association between sperm DNA fragmentation (SDF) and several clinical in vitro fertilization outcomes.

Methods

We retrospectively analyzed 169 consecutive fresh IVF cycles. Semen was collected on the day of oocyte retrieval, and we assessed standard semen parameters and the SDF level (by terminal deoxynucleotidyl transferase dUTP nick-end labeling). Poor ovarian response (POR) was defined as the collection of three or fewer mature oocytes. Oocytes were inseminated by the conventional method or intracytoplasmic sperm injection.

Results

SDF did not affect the fertilization or pregnancy rate, but did have a significant effect on the miscarriage rate. In the miscarriage group (n=10), the SDF level was significantly higher (23.9% vs. 14.1%) and number of mature oocytes was significantly lower (4.3 vs. 7.6) than in the live birth group (n=45). Multiple regression analysis showed that SDF was an independent predictor of miscarriage (odds ratio, 1.051; 95% confidence interval, 1.001–1.104). The cutoffs for the SDF level and number of mature oocytes that could predict miscarriage were >13% and ≤3, respectively. In the low-SDF group (≤13%), the miscarriage rate was similar in POR patients and those with a normal ovarian response (NOR; 14.2% vs. 4.3%). In the high-SDF group (>13%), the miscarriage rate was significantly higher in the POR group than in the NOR group (60.0% vs. 13.3%, p=0.045).

Conclusion

Our study demonstrated that a high SDF level (>13%) was associated with a high miscarriage rate, and that it mainly contributed to miscarriage in the POR group. The results suggest that SDF measurements should be considered in couples with POR in order to predict the prognosis of the pregnancy.

Impact of the Z potential technique on reducing the sperm DNA fragmentation index, fertilization rate and embryo development

Background

In assisted reproduction procedures, we need to develop and enhance new protocols to optimize sperm selection. The aim of this study is to evaluate the ability of the Z potential technique to select sperm with intact DNA in non-normospermic patients and evaluate the impact of this selection on embryonic development.

Methods

We analyzed a total of 174 human seminal samples with at least one altered parameter. We measured basal, post density gradients, and post density gradients + Z potential DNA fragmentation index. To evaluate the impact of this technique on embryo development, 54 cases were selected. The embryo development parameters evaluated were fertilization rate, cleavage rate, top quality embryos at the third day and blastocysts rate.

Results

We found significant differences in the study groups when we compared the sperm fragmentation index by adding the Z potential technique to density gradient selection vs. density gradients alone. Furthermore, there was no significant difference in the embryo development parameters between the low sperm fragmentation index group vs. the moderate and high sperm fragmentation index groups, when selecting sperms with this new technique.

Conclusions

The Z potential technique is a very useful tool for sperm selection; it significantly reduces the DNA fragmentation index and improves the parameters of embryo development. This technique could be considered routine for its simplicity and low cost.

DECREASED FERTILIZATION: HUMAN SPERM DNA FRAGMENTATION AND IN VITRO MATURATION OF OOCYTE IN STIMULATED ICSI CYCLES

Objective

The aim of this study was to evaluate the impact of sperm DNA fragmentation (SDF) on fertilization rate, and sperm nuclear decondensation after intracytoplasmic injection of sperm (ICSI) into cumulus-free germinal vesicle (GV) oocytes from stimulated cycles.

Methods and study design

After the retrieval of oocytes, the GV oocytes were cultured for 24 h. Oocytes that liberated polar bodies were injected with processed semen, and were used to evaluate SDF level. Based on SDF, the data were categorized into two groups. Group I in which SDF≤ 30% and group II in which SDF > 30%. Fertilization (presence of two pronuclei) was checked 16-19 h after ICSI. Unfertilized oocytes were stained by Hoechst 33258 and examined to evaluate the undecondensed sperm head in oocyte. The rates of maturation, fertilization in fertilized IVM oocytes and the percentage of undecondensed sperm in the unfertilized oocytes were assessed according to SDF.

Results

Out of 146 GV oocytes that were subjected to IVM, 101 (69 %) developed to metaphase II. The fertilization rate of IVM oocytes in group II was significantly lower than that in group I (P < 0.05). Moreover, group I, had 25 % of their unfertilized oocytes containing condensed sperm, while group II had a significantly higher number (53 %) of unfertilized oocytes containing condensed sperm (P < 0.05).

Conclusion

SDF had a negative effect on the rate of fertilization in matured in vitro GV oocytes and could lead to an increase in the percentage of undecondensed sperm in IVM oocytes from stimulated cycles.

Efficient isolation of sperm with high DNA integrity and stable chromatin packaging by a combination of density-gradient centrifugation and magnetic-activated cell sorting

OBJECTIVE

This study was carried out to investigate the correlations of the sperm DNA fragmentation index (DFI) with semen parameters and apoptosis, and to investigate the effects of density-gradient centrifugation (DGC) and magnetic-activated cell sorting (MACS) on reducing the proportion of sperm with DNA fragmentation and protamine deficiency.

METHODS

Semen analysis and a sperm DNA fragmentation assay were performed to assess the correlations between semen parameters and the DFI in 458 semen samples. Sperm with progressive motility or non-apoptosis were isolated by DGC or MACS, respectively, in 29 normozoospermic semen samples. The effects of DGC or MACS alone and of DGC and MACS combined on reducing the amount of sperm in the sample with DNA fragmentation and protamine deficiency were investigated.

RESULTS

The sperm DFI showed a significant correlation (r=-0.347, p<0.001) with sperm motility and morphology (r=-0.114, p<0.05) but not with other semen parameters. The DFI (11.5%±2.0%) of semen samples was significantly reduced by DGC (8.1%±4.1%) or MACS alone (7.4%±3.9%) (p<0.05). The DFI was significantly further reduced by a combination of DGC and MACS (4.1%±1.3%, p<0.05). Moreover, the combination of DGC and MACS (1.6%±1.1%, p<0.05) significantly reduced the protamine deficiency rate of semen samples compared to DGC (4.4%±3.2%) or MACS alone (3.4%±2.2%).

CONCLUSION

The combination of DGC and MACS may be an effective method to isolate high-quality sperm with progressive motility, non-apoptosis, high DNA integrity, and low protamine deficiency in clinical use.

Measuring Sperm DNA Fragmentation and Clinical Outcomes of Medically Assisted Reproduction: A Systematic Review and Meta-Analysis

Sperm DNA fragmentation has been associated with reduced fertilization rates, embryo quality, pregnancy rates and increased miscarriage rates. Various methods exist to test sperm DNA fragmentation such as the sperm chromatin structure assay (SCSA), the sperm chromatin dispersion (SCD) test, the terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labelling (TUNEL) assay and the single cell gel electrophoresis (Comet) assay. We performed a systematic review and meta-analysis to assess the value of measuring sperm DNA fragmentation in predicting chance of ongoing pregnancy with IVF or ICSI. Out of 658 unique studies, 30 had extractable data and were thus included in the meta-analysis. Overall, the sperm DNA fragmentation tests had a reasonable to good sensitivity. A wide variety of other factors may also affect the IVF/ICSI outcome, reflected by limited to very low specificity. The constructed hierarchical summary receiver operating characteristic (HSROC) curve indicated a fair discriminatory capacity of the TUNEL assay (area under the curve (AUC) of 0.71; 95% CI 0.66 to 0.74) and Comet assay (AUC of 0.73; 95% CI 0.19 to 0.97). The SCSA and the SCD test had poor predictive capacity. Importantly, for the TUNEL assay, SCD test and Comet assay, meta-regression showed no differences in predictive value between IVF and ICSI. For the SCSA meta-regression indicated the predictive values for IVF and ICSI were different. The present review suggests that current sperm DNA fragmentation tests have limited capacity to predict the chance of pregnancy in the context of MAR. Furthermore, sperm DNA fragmentation tests have little or no difference in predictive value between IVF and ICSI. At this moment, there is insufficient evidence to recommend the routine use of sperm DNA fragmentation tests in couples undergoing MAR both for the prediction of pregnancy and for the choice of treatment. Given the significant limitations of the evidence and the methodological weakness and design of the included studies, we do urge for further research on the predictive value of sperm DNA fragmentation for the chance of pregnancy after MAR, also in comparison with other predictors of pregnancy after MAR.