Selectivity of hyaluronic acid binding for spermatozoa with normal Tygerberg strict morphology

IZUMO1 Receptor Localization during Hyaluronic Acid Selection in Human Spermatozoa

IZUMO1 is an acrosome transmembrane protein implicated in the adhesion and fusion of gametes. This study aims to describe the distribution of IZUMO1 in human sperm under different physiological conditions: before capacitation (NCS), at one-hour capacitation (CS1), after a hyaluronic acid (HA) selection test (mature, MS1 and immature, IS1), and induced acrosome reaction from one-hour-capacitated sperm (ARS1). The data obtained in NCS, CS1, and MS1 significantly highlight dotted fluorescence in the acrosomal region (P1) as the major staining pattern (~70%). Moreover, we describe a new distribution pattern (P2) with a dotted acrosomal region and a labelled equatorial region that significantly increases in HA-bound spermatozoa, suggesting the onset of the migration of IZUMO1. In contrast, unbound spermatozoa presented an increase in P3 (equatorial region labelled) and P4 (not labelled). Finally, costaining to observe IZUMO1 distribution and acrosome status was performed in ARS1. Interestingly, we reported a variety of combinations between the IZUMO1 staining patterns and the acrosomal stages. In conclusion, these data show as a novelty the diffusion of the IZUMO1 protein during different physiological conditions that could contribute to the improvement in sperm selection techniques.

Physiological intracytoplasmic sperm injection does not improve the quality of embryos: A cross-sectional investigation on sibling oocytes

OBJECTIVE

This study aimed to compare the efficacy of physiological intracytoplasmic sperm injection (PICSI) and intracytoplasmic sperm injection (ICSI) in terms of the fertilization rate and embryo quality using sibling oocyte cycles.

METHODS

This prospective, cross-sectional study collected data from 76 couples who underwent their first cycle at the Hue Center for Reproductive Endocrinology and Infertility, Vietnam, between May 2019 and November 2021. The inclusion criteria were cycles with at least eight oocytes and a sperm concentration of 5×106/mL. Sperm parameters, sperm DNA fragmentation (SDF), fertilization, and the quality of cleavage-stage embryos on day 2 and blastocysts on day 5 were examined.

RESULTS

From 76 ICSI cycles, 1,196 metaphase II (MII) oocytes were retrieved, half of which were randomly allocated to either the PICSI (n=592) or ICSI (n=604) treatment group. The results showed no significant difference between the two groups in terms of fertilization (72.80% vs. 75.33%, p=0.32), day 2 cleavage rate (95.13% vs. 96.04%, p=0.51), blastulation rate (52.68% vs. 57.89%), and high-quality blastocyst rate (26.10% vs. 31.13%, p=0.13). However, in cases where SDF was low, 59 cycles consisting of 913 MII oocytes produced a considerably higher blastulation rate with PICSI than with ICSI (50.49% vs. 35.65%, p=0.00). There were no significant differences between the pregnancy outcomes of the PICSI and ICSI embryo groups following embryo transfer.

CONCLUSION

Using variable sperm quality provided no benefit for PICSI versus ICSI in terms of embryo outcomes. When SDF is low, PICSI appears to be able to produce more blastocysts.

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.

Male subfertility and oxidative stress

To date 15% of couples are suffering from infertility with 45-50% of males being responsible. With an increase in paternal age as well as various environmental and lifestyle factors worsening these figures are expected to increase. As the so-called free radical theory of infertility suggests, free radicals or reactive oxygen species (ROS) play an essential role in this process. However, ROS also fulfill important functions for instance in sperm maturation. The aim of this review article is to discuss the role reactive oxygen species play in male fertility and how these are influenced by lifestyle, age or disease. We will further discuss how these ROS are measured and how they can be avoided during in-vitro fertilization.

A successful healthy childbirth and an ongoing evolutive pregnancy in a case of partial globozoospermia by hyaluronic acid sperm selection

We here report a successful healthy childbirth and an ongoing evolutive pregnancy in a case of partial globozoospermia after selection of mature spermatozoa bound to hyaluronic acid (HA). The couple underwent two in vitro fertilisation (IVF) cycles. In the first attempt, 14 MII oocytes were retrieved. Randomly, seven oocytes were injected by conventional PVP-ICSI and seven by HA-ICSI. Fertilised oocytes were 2/7 and 4/7 after PVP-ICSI and HA-ICSI respectively. Transfer of two grade A embryos from HA-ICSI lead to birth of a healthy baby. The surplus embryo of the HA-ICSI group was vitrified at blastocyst stage. The two embryos from PVP-ICSI arrested their development. Two years after the childbirth, the vitrified blastocyst was transferred into the uterus, but implant failed. In the second cycle, 14 MII oocytes were retrieved and they were injected by HA-ICSI. Fertilised oocytes were 10 out of 14 injected oocytes. On day 5, two blastocysts were transferred into uterus and a single evolutive pregnancy is ongoing. On day 6, one blastocyst was vitrified. The remaining surplus embryos arrested their development. A healthy childbirth and an ongoing evolutive pregnancy in two consecutive ICSI attempts of the same couple suggest that HA sperm selection might assist in cases with partial globozoospermia.

Clinical assessment of the male fertility

The evaluation of infertility in males consists of physical examination and semen analyses. Standardized semen analyses depend on the descriptive analysis of sperm motility, morphology, and concentration, with a threshold level that must be surpassed to be considered a fertile spermatozoon. Nonetheless, these conventional parameters are not satisfactory for clinicians since 25% of infertility cases worldwide remain unexplained. Therefore, newer tests methods have been established to investigate sperm physiology and functions by monitoring characteristics such as motility, capacitation, the acrosome reaction, reactive oxygen species, sperm DNA damage, chromatin structure, zona pellucida binding, and sperm-oocyte fusion. After the introduction of intracytoplasmic sperm injection technique, sperm maturity, morphology, and aneuploidy conditions have gotten more attention for investigating unexplained male infertility. In the present article, recent advancements in research regarding the utilization of male fertility prediction tests and their role and accuracy are reviewed.

Effect of erythrocyte-sperm separation medium on nuclear, acrosomal, and membrane maturity parameters in human sperm

PURPOSE

The purpose of this study is to investigate whether erythrocyte-sperm separation medium (ESSM) has effects on human sperm motility, morphology, viability, membrane maturity, acrosome integrity, and nuclear attributes before and after cryopreservation.

METHODS

Semen samples from normozoospermic (n = 36) and oligozoospermic (n = 9) patients were analyzed. Samples from the same patient were divided into three aliquots: group 1 and group 2 were resuspended in sperm washing media and ESSM, respectively. Group 3 was resuspended in ESSM with blood sample to mimic the extensive number of erythrocytes in the testicular sperm extraction (TESE) material. All groups were evaluated for sperm concentration, motility, Kruger/Tygerberg strict morphology, viability by eosin-nigrosin staining, membrane maturity by hyaluronic acid-binding assay (HBA), acrosomal integrity by Pisum sativum lectin staining, chromatin maturity by aniline blue staining, and DNA integrity by TUNEL assay before and after cryopreservation.

RESULTS

No significant difference was determined between ESSM-treated and ESSM-untreated sperm samples for the sperm parameters tested (p > 0.05). After cryopreservation, total sperm motility and viability decreased regardless of ESSM used. The percentages of sperm with Tygerberg normal morphology, intact acrosome, and HA-bound sperm were found to be lower in oligozoospermic samples before cryopreservation in each group. However, no statistically significant differences were found between oligozoospermic and normozoospermic samples when all groups were compared. Thus, ESSM treatment did not cause a significant change on sperm motility, normal morphology, viability, HA-binding capacity, chromatin maturity, and DNA fragmentation.

CONCLUSION

ESSM can enhance the efficiency of sperm retrieval protocol and can also decrease the time required to collect spermatozoa while not affecting sperm morphogenetic properties.

Hyaluronan-binding system for sperm selection enhances pregnancy rates in ICSI cycles associated with male factor infertility

OBJECTIVES

The aim of the present study was to compare two procedures for sperm selection in ICSI cycles - conventional morphology sperm selection (ICSI-PVP) and chemical selection through Hyaluronan-treated petri dishes (PICSI), when male factor was associated.

METHODS

The evaluated parameters were semen quality, fertilization and cleavage rates, chemical and clinical pregnancy rates, as well as abortion rate. Fifty-six ICSI cycles were included in this report, 19 cycles using PICSI and 37 using conventional ICSI.

RESULTS

PICSI and ICSI showed, respectively, the following outcome: fertilization rates 71.93% (123/171) and 64.14% (127/198); cleavage rates 95.12% (117/123) and 95.27% (121/127); chemical pregnancy rates 63.15% (12/19) and 27.03% (10/37); clinical pregnancy rates 42.10% (8/19) and 16.21% (6/37); and abortion rates 33.33% (4/12) and 40.00% (4/10). According to both Fisher's Exact Test and Chi-square Test, chemical pregnancy (p = 0.05) and clinical pregnancy (p = 0.09) rates were significantly higher in the PICSI group. p values ≤ 0.05 were consider statistically significant.

CONCLUSIONS

The present data indicates that ICSI cycles that used the PICSI technique had a considerably higher chance (≈5 fold) to achieve pregnancy than those who had sperm selected only by morphology assessment. Teratozoospermic patients were those who benefited most with PICSI. Therefore, the technique should be included in laboratory routine with low cost, avoiding the selection of immature sperm with increased rates of peroxidation and DNA fragmentation. Prospective and randomized studies should be applied to strengthen this suggestion.

Hyaluronic Acid Binding Sperm Selection for assisted reproduction treatment (HABSelect): study protocol for a multicentre randomised controlled trial

INTRODUCTION

The selection of a sperm with good genomic integrity is an important consideration for improving intracytoplasmic sperm injection (ICSI) outcome. Current convention selects sperm by vigour and morphology, but preliminary evidence suggests selection based on hyaluronic acid binding may be beneficial. The aim of the Hyaluronic Acid Binding Sperm Selection (HABSelect) trial is to determine the efficacy of hyaluronic acid (HA)-selection of sperm versus conventionally selected sperm prior to ICSI on live birth rate (LBR). The mechanistic aim is to assess whether and how the chromatin state of HA-selected sperm corresponds with clinical outcomes-clinical pregnancy rate (CPR), LBR and pregnancy loss (PL).

METHODS AND ANALYSIS

Couples attending UK Centres will be approached, eligibility screening performed and informed consent sought. Randomisation will occur within 24 hours prior to ICSI treatment. Participants will be randomly allocated 1:1 to the intervention arm (physiological intracytoplasmic sperm injection, PICSI) versus the control arm using conventional methods (ICSI). The primary clinical outcome is LBR ≥37 weeks' gestation with the mechanistic study determining LBR's relationship with sperm DNA integrity. Secondary outcomes will determine this for CPR and PL. Only embryologists performing the procedure will be aware of the treatment allocation. Steps will be taken to militate against biases arising from embryologists being non-blinded. Randomisation will use a minimisation algorithm to balance for key prognostic variables. The trial is powered to detect a 5% difference (24-29%: p=0.05) in LBR ≥37 weeks' gestation. Selected residual sperm samples will be tested by one or more assays of DNA integrity.

ETHICS AND DISSEMINATION

HABSelect is a UK NIHR-EME funded study (reg no 11/14/34; IRAS REF. 13/YH/0162). The trial was designed in partnership with patient and public involvement to help maximise patient benefits. Trial findings will be reported as per CONSORT guidelines and will be made available in lay language via the trial web site (http://www.habselect.org.uk/).

TRIAL REGISTRATION NUMBER

ISRCTN99214271; Pre-results.

Hyaluronic Acid Binding Assay Is Highly Sensitive to Select Human Spermatozoa with Good Progressive Motility, Morphology, and Nuclear Maturity

OBJECTIVE

This study was performed to evaluate the correlation of hyaluronic acid binding assay (HBA) with conventional semen parameters, lipid peroxidation (LPO), intracellular reactive oxygen species (ROS), DNA fragmentation (DF), DNA maturity and mitochondrial membrane potential (MMP) level in human spermatozoa.

METHODS

The semen samples were obtained from 98 patients. The seminal plasma was separated for the study of LPO, and the pellet was employed for evaluation of intracellular ROS, DF, nuclear maturity (sperm chromatin structure assay) and MMP through flowcytometry.

RESULTS

The correlation and strength of HBA with respect to the studied parameters were estimated by the Pearson coefficient and multiple liner regression tests. While HBA indicated a positive correlation with progressive motility (β-coefficients = 0.449, p < 0.05) and normal morphology (β-coefficients = 2.722, p < 0.01), it had only negative relationship with DNA integrity (high DNA stain ability; β-coefficients = -0.517, p < 0.05). HBA also did not show any important correlation with other conventional and intracellular sperm parameters.

CONCLUSIONS

The HBA is sensitive to morphological integrity, high progressive motility and nuclear maturation. Nonetheless, HBA is not a reliable test for prediction of sperm intracellular ROS, DF and MMP risks and healthy spermatozoa selection.

Varicocele decreases epididymal neutral α-glucosidase and is associated with alteration of nuclear DNA and plasma membrane in spermatozoa

OBJECTIVE

To assess the relationship between a marker of epididymal function and both the fragmentation of the sperm nucleus and the integrity and maturity of the sperm membrane in patients with or without varicocele.

PATIENTS AND METHODS

Semen samples were obtained from men with varicocele grades II and III (n = 60) and from a control group with zoospermia defined as normal (n = 30). Samples were evaluated by a spermiogram, a hypoosmotic swelling test (HOST), neutral α-glucosidase (NAG) enzyme activity, sperm hyaluronan-binding assay (HBA) and DNA fragmentation using a sperm chromatin dispersion (SCD) test.

RESULTS

Seminal plasma NAG levels, percentage of sperm bound to hyaluronic acid, HOST-positive cells and sperm quality were significantly lower in the varicocele compared with the control group. Higher levels of sperm DNA fragmentation, as measured by SCD, were also observed in the varicocele group compared with the control group. Seminal NAG activity levels showed a strong negative correlation with DNA fragmentation and a significant positive correlation with the HBA test and the HOST.

CONCLUSIONS

Varicocele causes a reduction in NAG activity by the epididymis that is associated with damage to both the membrane and sperm nucleus and a reduction in the seminal parameters. NAG levels were correlated with the quality of the sperm membrane and nucleus. Data suggest that a reduction of fertilization capacity in men during varicocele can result from damage to both the testis and the epididymis.

Assessing the reproductive health of men with occupational exposures

The earliest report linking environmental (occupational) exposure to adverse human male reproductive effects dates back to1775 when an English physician, Percival Pott, reported a high incidence of scrotal cancer in chimney sweeps. This observation led to safety regulations in the form of bathing requirements for these workers. The fact that male-mediated reproductive harm in humans may be a result of toxicant exposures did not become firmly established until relatively recently, when Lancranjan studied lead-exposed workers in Romania in 1975, and later in 1977, when Whorton examined the effects of dibromochloropropane (DBCP) on male workers in California. Since these discoveries, several additional human reproductive toxicants have been identified through the convergence of laboratory and observational findings. Many research gaps remain, as the pool of potential human exposures with undetermined effects on male reproduction is vast. This review provides an overview of methods used to study the effects of exposures on male reproduction and their reproductive health, with a primary emphasis on the implementation and interpretation of human studies. Emphasis will be on occupational exposures, although much of the information is also useful in assessing environmental studies, occupational exposures are usually much higher and better defined.

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.

A prospective randomized study to evaluate the effect of hyaluronic acid sperm selection on the intracytoplasmic sperm injection outcome of patients with unexplained infertility having normal semen parameters

PURPOSE

Sperm quality plays an important role in determining embryo development and intracytoplasmic sperm injection (ICSI) outcome. Selection of competent sperm based on its ability to bind to hyaluronic acid (HA) has been suggested as one of the methods to assess sperm quality. The aim of the present study was to examine whether injection of HA bound sperm helps in improving outcome in patients undergoing ICSI with unexplained infertility having normal semen parameters.

METHODS

Patients with unexplained infertility having normal semen parameters in accordance with WHO 2010 criterion, undergoing their first IVF-ICSI cycle were enrolled during the course of the study.156 patients were prospectively randomized after oocyte retrieval and were assigned to either the ICSI group, where sperm selection for injection was based on visual assessment, or the PICSI group, where sperm were selected based on their ability to bind to HA. Only fresh embryo transfers were included in the analysis.

RESULTS

There was no difference in the fertilization rates, number of top quality embryos and clinical pregnancy rates between the ICSI and PICSI groups (65.7 % vs 64.7 %; 45.8 % vs 43.6 % and 35 % vs 35.2 % respectively). However, a higher pregnancy loss rate was observed in the ICSI group (25 % vs 12 %; P = 0.227) as compared to the PICSI group, but the difference was not statistically significant. Implantation rates were 22.03 % and 18.84 % in the PICSI and ICSI groups respectively. There were 22 (31 %) live births in the PICSI group and 21(26.3 %) live births in the ICSI group.

CONCLUSIONS

Patients with unexplained infertility having normal semen parameters may constitute a patient group which does not benefit from this sperm selection method. A larger study may be necessary to establish a relationship between PICSI and pregnancy loss rate in patients undergoing IVF with unexplained infertility.

Scoring human sperm morphology using Testsimplets and Diff-Quik slides

OBJECTIVE

To compare two staining methods to assess sperm morphology: Diff-Quik (DQ), which is the fastest of the recommended techniques, and Testsimplets (TS), a technique that uses prestained slides and is quite popular in in vitro fertilization (IVF) centers.

DESIGN

Prospective study.

SETTING

Patients at the Sterility Center of the Obstetrics and Gynecology Unit of the Hospital of S.S. Cosma and Damiano (Azienda USL 3 of Pistoia, Italy).

PATIENT(S)

104 randomly enrolled male patients evaluated by the seminology laboratory.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Statistical comparison of sperm morphology results obtained after staining of semen samples both with DQ and TS.

RESULT(S)

Our data show that TS gives a statistically significantly lower number of normal forms than DQ (median: 6% [range: 0-29%] vs. 12% [range: 0-40%], respectively) as well as an overestimation of sperm head defects (median: 92.0% [range: 67%-100%] vs. 82.3% [range: 55%-100%], respectively).

CONCLUSION(S)

The two staining methods should not be considered equivalent. Specifically, the lower reference limit established by the World Health Organization is not appropriate when sperm morphology is assessed by TS. The routine application of TS in the evaluation of sperm morphology is therefore not recommended because it leads to an overestimation of patients with sperm morphology values below the lower reference limit (4%), thus potentially influencing clinical decisions.

Sperm morphology classification: a rational method for schemes adopted by the world health organization

Sperm morphology is an important measure of testicular health, spermiation, and fertility potential. The World Health Organization (WHO) Semen Manuals advocate different sperm morphology schemes, but, like the schemes themselves, do not describe classification sequence or rules that can be unambiguously applied in a standard method. Our novel dichotomous key provides a rational decision framework for a sperm morphology classification algorithm. Classification order hierarchy is standardized and sperm characteristics are defined. Normal morphology is derived after eliminating abnormal and borderline normal forms. By defining and categorizing borderline normal forms separately from either normal or abnormal, the method can simultaneously produce results for Strict and traditional morphology schemes as adopted by different versions of the WHO Semen Manuals. The algorithm can be used for "recalibration" to a less stringent and potentially more relevant standard of normal, while reducing shift, drift, and variation in classification within and among analysts.

Sperm selection for ICSI using the hyaluronic acid binding assay

Sperm selection is an important part of the ICSI procedure. Routinely, sperm selection for ICSI is based solely on sperm morphology and motility. These latter parameters may not be sufficient to select sperm with intact chromatin. Therefore, sperm selected based on sperm functional characteristics may result in the most appropriate sperm for the ICSI procedure. The methodology explained below describes the selection of sperm based on the ability of sperm to bind solid-state hyaluronic acid as its receptor, present on mature sperm with intact chromatin.

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

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

Application of sperm selection using hyaluronic acid binding in intracytoplasmic sperm injection cycles: a sibling oocyte study

The purpose of this study was to investigate whether sperm selection by hyaluronic acid (HA) binding could improve fertilization rate and embryo quality in intracytoplasmic sperm injection (ICSI) cycles. Two hundred nineteen oocytes obtained from eighteen women were injected with either HA-bound (n = 107) or conventionally selected spermatozoa (n = 112) in a randomized way. All of the participants were infertile couples who had normal sperm parameters but low fertilization rate in previous in vitro fertilization (IVF) cycle (n = 5) or experienced multiple IVF failures (n = 13). Lower fertilization (75.7% vs 83.0%) and cleavage rate on day 2 (72.9% vs 83.0%) was observed in oocytes injected with HA-bound spermatozoa than the conventional group, but the difference was not significant. Significantly lower cleavage rate was observed on day 3 in HA group (56.0% vs 69.6%, P = 0.038). Blastocyst formation rate and the number of transferred embryos were similar in both groups. In multiple IVF failure patients, significantly reduced fertilization rate (71.8% vs 85.3%, P = 0.046) and cleavage rate on day 2 (70.4% vs 85.3%, P = 0.029) and day 3 (53.5% vs 77.3%, P = 0.002) were noticed in HA group. Five women achieved pregnancy continuing more than 12 weeks after transfer (27.8%). Success of ICSI was not related with the number of embryos fertilized by HA-bound spermatozoa. Application of ICSI by sperm selection using HA binding is not helpful in couples with repeated poor fertilization or implantation despite normal sperm parameters.

The effect of sperm DNA fragmentation on miscarriage rates: a systematic review and meta-analysis

STUDY QUESTION

Is there an association between high levels of sperm DNA damage and miscarriage?

SUMMARY ANSWER

Miscarriage rates are positively correlated with sperm DNA damage levels.

WHAT IS KNOWN ALREADY

Most ejaculates contain a subpopulation of sperm with DNA damage, also referred to as DNA fragmentation, in the form of double or single-strand breaks which have been induced in the DNA prior to or following ejaculation. This DNA damage may be particularly elevated in some subfertile men, hence several studies have examined the link between sperm DNA damage levels and conception and miscarriage rates.

STUDY DESIGN, SIZE, DURATION

A systematic review and meta-analysis of studies which examined the effect of sperm DNA damage on miscarriage rates was performed. Searches were conducted on MEDLINE, EMBASE and the Cochrane Library without any language restrictions from database inception to January 2012.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We used the terms 'DNA damage' or 'DNA fragmentation' combined with 'miscarriage', 'abortion' or 'pregnancy' to generate a set of relevant citations. Data extraction was performed by two reviewers. Study quality was assessed using the Newcastle-Ottawa Scale. Meta-analysis of relative risks of miscarriage was performed with a random effects model. Subgroup analyses were performed by the type of DNA damage test, whether the sperm examined were prepared or from raw semen and for pregnancies resulting from IVF or ICSI treatment.

MAIN RESULTS AND THE ROLE OF CHANCE

We identified 16 cohort studies (2969 couples), 14 of which were prospective. Eight studies used acridine orange-based assays, six the TUNEL assay and two the COMET assay. Meta-analysis showed a significant increase in miscarriage in patients with high DNA damage compared with those with low DNA damage [risk ratio (RR) = 2.16 (1.54, 3.03), P < 0.00001)]. A subgroup analysis showed that the miscarriage association is strongest for the TUNEL assay (RR = 3.94 (2.45, 6.32), P < 0.00001).

LIMITATIONS, REASONS FOR CAUTION

There is some variation in study characteristics, including the use of different assays and different thresholds for DNA damage and the definition of pregnancy loss.

WIDER IMPLICATIONS OF THE FINDINGS

The use of methods which select sperm without DNA damage for use in assisted conception treatment may reduce the risk of miscarriage. This finding indicates that assays detecting DNA damage could be considered in those suffering from recurrent pregnancy loss. Further research is necessary to study the mechanisms of DNA damage and the potential therapeutic effects of antioxidant therapy.

STUDY FUNDING/COMPETING INTEREST(S)

None.

Effects of advanced selection methods on sperm quality and ART outcome: a systematic review

BACKGROUND

Current routine semen preparation techniques do not inclusively target all intrinsic sperm characteristics that may impact the fertilization potential. In order to address these characteristics, several methods have been recently developed and applied to sperm selection. The objective of this study was to systematically review the literature describing these advanced sperm selection methods focusing on their anticipated benefits on sperm quality and assisted reproductive technique (ART) outcome.

METHODS

Systematic literature review was conducted by means of a Medline literature search. Sperm quality parameters assessed included: motility, morphology, viability, DNA integrity, apoptosis and maturity. ART outcomes assessed included: fertilization, embryo quality, pregnancy, abortion and live birth rates.

RESULTS

A total of 44 studies were identified describing four advanced sperm selection methods based on: (i) surface charge (electrophoresis and zeta potential), (ii) apoptosis (magnetic cell sorting and glass wool), (iii) membrane maturity (hyaluronic acid binding) and (iv) ultramorphology (high magnification). Selection of high-quality sperm including improvements in DNA integrity, resulted from the application of these methods. Fertilization and pregnancy rates showed improvement following some of the advanced sperm selection techniques.

CONCLUSIONS

While some of the advanced sperm selection methods are of value in specific clinical ART settings, others are in need of further evaluation. More clinical studies on safety and efficacy are needed before the implementation of advanced sperm selection methods could be universally recommended in ART.

Efficacy of the motile sperm organelle morphology examination (MSOME) in predicting pregnancy after intrauterine insemination

BACKGROUND

Although the motile sperm organelle morphology examination (MSOME) was developed merely as a selection criterion, its application as a method for classifying sperm morphology may represent an improvement in the evaluation of semen quality. The aim of this study was to determine the prognostic value of normal sperm morphology using MSOME with regard to clinical pregnancy (CP) after intrauterine insemination (IUI).

METHODS

A total of 156 IUI cycles that were performed in 111 couples were prospectively analysed. Each subject received 75 IU of recombinant FSH every second day from the third day of the cycle. Beginning on the 10th day of the cycle, follicular development was monitored by vaginal ultrasound. When one or two follicles measuring at least 17 mm were observed, recombinant hCG was administered, and IUI was performed 12-14 h and 36-40 h after hCG treatment. Prior to the IUI procedure, sperm samples were analysed by MSOME at 8400× magnification using an inverted microscope that was equipped with DIC/Nomarski differential interference contrast optics. A minimum of 200 motile spermatozoa per semen sample were evaluated, and the percentage of normal spermatozoa in each sample was determined.

RESULTS

Pregnancy occurred in 34 IUI cycles (CP rate per cycle: 21.8%, per patient: 30.6%). Based on the MSOME criteria, a significantly higher percentage of normal spermatozoa was found in the group of men in which the IUI cycles resulted in pregnancy (2.6+/-3.1%) compared to the group that did not achieve pregnancy (1.2+/-1.7%; P = 0.019). Logistic regression showed that the percentage of normal cells in the MSOME was a determining factor for the likelihood of clinical pregnancy (OR: 1.28; 95% CI: 1.08 to 1.51; P = 0.003). The ROC curve revealed an area under the curve of 0.63 and an optimum cut-off point of 2% of normal sperm morphology. At this cut-off threshold, using the percentage of normal sperm morphology by MSOME to predict pregnancy was 50% sensitive with a 40% positive predictive value and 79% specificity with an 85% negative predictive value. The efficacy of using the percentage of normal sperm morphology by MSOME in predicting pregnancy was 65%.

CONCLUSIONS

The present findings support the use of high-magnification microscopy both for selecting spermatozoa and as a routine method for analysing semen before performing IUI.

Efficacy of hyaluronic acid binding assay in selecting motile spermatozoa with normal morphology at high magnification

BACKGROUND

The present study aimed to evaluate the efficacy of the hyaluronic acid (HA) binding assay in the selection of motile spermatozoa with normal morphology at high magnification (8400x).

METHODS

A total of 16592 prepared spermatozoa were selected and classified into two groups: Group I, spermatozoa which presented their head attached to an HA substance (HA-bound sperm), and Group II, those spermatozoa that did not attach to the HA substance (HA-unbound sperm). HA-bound and HA-unbound spermatozoa were evaluated according to the following sperm forms: 1-Normal morphology: normal nucleus (smooth, symmetric and oval configuration, length: 4.75+/-2.8 μm and width: 3.28+/-0.20 μm, no extrusion or invagination and no vacuoles occupied more than 4% of the nuclear area) as well as acrosome, post-acrosomal lamina, neck, tail, besides not presenting a cytoplasmic droplet or cytoplasm around the head; 2-Abnormalities of nuclear form (a-Large/small; b-Wide/narrow; c-Regional disorder); 3-Abnormalities of nuclear chromatin content (a-Vacuoles: occupy >4% to 50% of the nuclear area and b-Large vacuoles: occupy >50% of the nuclear area) using a high magnification (8400x) microscopy system.

RESULTS

No significant differences were obtained with respect to sperm morphological forms and the groups HA-bound and HA-unbound. 1-Normal morphology: HA-bound 2.7% and HA-unbound 2.5% (P = 0.56). 2-Abnormalities of nuclear form: a-Large/small: HA-bound 1.6% vs. HA-unbound 1.6% (P = 0.63); b-Wide/narrow: HA-bound 3.1% vs. HA-unbound 2.7% (P = 0.13); c-Regional disorders: HA-bound 4.7% vs. HA-unbound 4.4% (P = 0.34). 3. Abnormalities of nuclear chromatin content: a-Vacuoles >4% to 50%: HA-bound 72.2% vs. HA-unbound 72.5% (P = 0.74); b-Large vacuoles: HA-bound 15.7% vs. HA-unbound 16.3% (P = 0.36).

CONCLUSIONS

The findings suggest that HA binding assay has limited efficacy in selecting motile spermatozoa with normal morphology at high magnification.