Fertility testing and ICSI sperm selection by hyaluronic acid binding: clinical and genetic aspects

Aberrant landscapes of maternal meiotic crossovers contribute to aneuploidies in human embryos

Meiotic recombination is crucial for human genetic diversity and chromosome segregation accuracy. Understanding its variation across individuals and the processes by which it goes awry are long-standing goals in human genetics. Current approaches for inferring recombination landscapes rely either on population genetic patterns of linkage disequilibrium (LD)-capturing a time-averaged view-or on direct detection of crossovers in gametes or multigeneration pedigrees, which limits data set scale and availability. Here, we introduce an approach for inferring sex-specific recombination landscapes using data from preimplantation genetic testing for aneuploidy (PGT-A). This method relies on low-coverage (<0.05×) whole-genome sequencing of in vitro fertilized (IVF) embryo biopsies. To overcome the data sparsity, our method exploits its inherent relatedness structure, knowledge of haplotypes from external population reference panels, and the frequent occurrence of monosomies in embryos, whereby the remaining chromosome is phased by default. Extensive simulations show our method's high accuracy, even at coverages as low as 0.02×. Applying this method to PGT-A data from 18,967 embryos, we mapped 70,660 recombination events with ∼150 kbp resolution, replicating established sex-specific recombination patterns. We observed a reduced total length of the female genetic map in trisomies compared with disomies, as well as chromosome-specific alterations in crossover distributions. Based on haplotype configurations in pericentromeric regions, our data indicate chromosome-specific propensities for different mechanisms of meiotic error. Our results provide a comprehensive view of the role of aberrant meiotic recombination in the origins of human aneuploidies and offer a versatile tool for mapping crossovers in low-coverage sequencing data from multiple siblings.

Sperm selection by zona adhesion improves assisted reproductive treatment outcomes

BACKGROUND

Zona pellucida is one of the main selective barriers for the spermatozoa before reaching the oocyte. Using native zona in the sperm selection prior to Intracytoplasmic Sperm Injection (ICSI) has been proven effective but inconvenient approach in In Vitro Fertilisation (IVF) laboratory. The application of autologous solubilised zonae pellucidae in the sperm selection prior to ICSI has not been studied yet.

OBJECTIVES

To compare the assisted reproductive treatment (ART) outcomes (implantation, pregnancy, live birth, and miscarriage rates) after ICSI performed with spermatozoa selected on their ability to adhere to immobilised solubilised zonae pellucidae and conventionally selected spermatozoa.

MATERIALS AND METHODS

In total, 500 couples fulfilled the inclusion criteria and 368 of them were included in the study. After random allocation, 192 couples had spermatozoa selected by sperm-zona adhesion for ICSI (study group) and 176 patients underwent standard ICSI (control group). In the study group, patients' own zonae were acid solubilised and immobilised on petri dishes. The partner's motile spermatozoa were placed in the dishes and the adhered spermatozoa were used for ICSI. For the control group, the conventional sperm selection by morphological criteria was applied prior ICSI. All women underwent frozen ET with euploid embryos. Chi square test was used to compare the data.

RESULTS

The sperm selection by zona adhesion resulted in significantly higher implantation rate (50.4% vs. 37.0%, p = 0.003), clinical pregnancy rate (43.8% vs. 33.3%, p = 0.018) and live birth rate (38.0% vs. 25.9%, p = 0.004) and significantly lower incidence of miscarriage (11.3% vs. 22.2%, p = 0.044) in comparison to the conventional method of the sperm selection.

DISCUSSION AND CONCLUSION

The application of solubilised zonae pellucidae in the sperm selection for ICSI benefits ART outcomes in couples with unexplained infertility. Moreover, sperm-zona selection significantly reduces the risk of miscarriages.

Evolution of intracytoplasmic sperm injection: From initial challenges to wider applications

Background

In vitro fertilization (IVF) has revolutionized infertility treatment. Nevertheless, male infertility requires more effective solutions. In 1992, the first-ever case of human birth via intracytoplasmic sperm injection (ICSI) was reported. ICSI involves microscopically injecting a sperm into an ovum. Successful ICSI has become a reliable therapy for couples facing infertility, a significant milestone. However, it has also introduced various challenges. This study also delves into ethical dilemmas arising from widespread ICSI use.

Methods

This review traces the history of ICSI, presenting pioneering attempts, first successful attempts, and critical reports on account of the initial skepticism toward the technology. The review also focuses on chronological progress until ICSI was recognized as effective and became widely applied.

Main findings

The review reveals that ICSI, although transformative, presents challenges. Successes include addressing male infertility and aiding fertilization. However, concerns arise regarding optimal sperm and embryo selection, genetic mutations, and long-term health implications. Ethical considerations surrounding ICSI's broad applications also surface.

Conclusions

Despite its success and effectiveness, ICSI is still evolving as a therapeutic method. By comprehensively evaluating the historical progress and the current status of ICSI and exploring its future prospects, this study highlights the importance of ICSI in infertility treatment.

Aberrant landscapes of maternal meiotic crossovers contribute to aneuploidies in human embryos

Meiotic recombination is crucial for human genetic diversity and chromosome segregation accuracy. Understanding its variation across individuals and the processes by which it goes awry are long-standing goals in human genetics. Current approaches for inferring recombination landscapes either rely on population genetic patterns of linkage disequilibrium (LD)-capturing a time-averaged view-or direct detection of crossovers in gametes or multi-generation pedigrees, which limits dataset scale and availability. Here, we introduce an approach for inferring sex-specific recombination landscapes using data from preimplantation genetic testing for aneuploidy (PGT-A). This method relies on low-coverage (<0.05×) whole-genome sequencing of in vitro fertilized (IVF) embryo biopsies. To overcome the data sparsity, our method exploits its inherent relatedness structure, knowledge of haplotypes from external population reference panels, as well as the frequent occurrence of monosomies in embryos, whereby the remaining chromosome is phased by default. Extensive simulations demonstrate our method's high accuracy, even at coverages as low as 0.02×. Applying this method to PGT-A data from 18,967 embryos, we mapped 70,660 recombination events with ~150 kbp resolution, replicating established sex-specific recombination patterns. We observed a reduced total length of the female genetic map in trisomies compared to disomies, as well as chromosome-specific alterations in crossover distributions. Based on haplotype configurations in pericentromeric regions, our data indicate chromosome-specific propensities for different mechanisms of meiotic error. Our results provide a comprehensive view of the role of aberrant meiotic recombination in the origins of human aneuploidies and offer a versatile tool for mapping crossovers in low-coverage sequencing data from multiple siblings.

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.

New horizons in human sperm selection for assisted reproduction

Male infertility is a commonly encountered pathology that is estimated to be a contributory factor in approximately 50% of couples seeking recourse to assisted reproductive technologies. Upon clinical presentation, such males are commonly subjected to conventional diagnostic andrological practices that rely on descriptive criteria to define their fertility based on the number of morphologically normal, motile spermatozoa encountered within their ejaculate. Despite the virtual ubiquitous adoption of such diagnostic practices, they are not without their limitations and accordingly, there is now increasing awareness of the importance of assessing sperm quality in order to more accurately predict a male's fertility status. This realization raises the important question of which characteristics signify a high-quality, fertilization competent sperm cell. In this review, we reflect on recent advances in our mechanistic understanding of sperm biology and function, which are contributing to a growing armory of innovative approaches to diagnose and treat male infertility. In particular we review progress toward the implementation of precision medicine; the robust clinical adoption of which in the setting of fertility, currently lags well behind that of other fields of medicine. Despite this, research shows that the application of advanced technology platforms such as whole exome sequencing and proteomic analyses hold considerable promise in optimizing outcomes for the management of male infertility by uncovering and expanding our inventory of candidate infertility biomarkers, as well as those associated with recurrent pregnancy loss. Similarly, the development of advanced imaging technologies in tandem with machine learning artificial intelligence are poised to disrupt the fertility care paradigm by advancing our understanding of the molecular and biological causes of infertility to provide novel avenues for future diagnostics and treatments.

Effects of sperm processing techniques on IVF pregnancy rates: a mini-review

Many factors associated with assisted reproductive technologies significantly influence the success of pregnancy after in vitro fertilization (IVF) either directly or indirectly. These factors include sperm processing techniques, egg retrieval, intrauterine artificial insemination, intracytoplasmic sperm injection, and embryo transfer. Among these technologies, sperm quality is one of the most critical factors for a successful IVF pregnancy. The method used for sperm processing plays a crucial role in determining the quality of sperm. Several widely used sorting techniques, such as conventional swim-up, density gradient centrifugation, magnetic activated cell sorting, and hyaluronic acid, have been extensively compared in various studies. Previous studies have shown that each sperm processing method causes varying degrees of sperm damage, particularly in sperm motility, concentration, morphological features, viability, and DNA integrity. However, sperm processing techniques have been developed slowly, and the impact of these methods on pregnancy rates is still unclear. Further exploration is needed. In this review, we aim to compare the results of different sperm processing techniques concerning sperm quality and IVF pregnancy rates. We will also discuss possible clinical approaches, such as microfluidics and integrated approaches, for testing and improving sperm quality.

A Review of the Impact of Microfluidics Technology on Sperm Selection Technique

Sperm sorting procedures depend on centrifugation processes. These processes produce oxidative stress and cell damage that are undesirable for in-vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) outcomes because they affect fertilization and implantation chances. The microfluidic sperm selection technique has shown promise in this area. It can create a platform for isolating and manipulating good-quality sperm cells using diverse triggers such as mechanical factors, chemical agents, and temperature gradients. Furthermore, microfluidic platforms can direct sperm cells for IVF or sperm sorting by utilizing an approach that is passive or active. In this review, we explain the use of microfluidics technologies for sorting and arranging sperm cells for different purposes. We also discuss the use of microfluidics technology in selecting and assessing sperm parameters and how it affects male infertility.

The Effect of Sperm DNA Fragmentation on Male Fertility and Strategies for Improvement: A Narrative Review

The inability to conceive due to male infertility is a complex issue with a wide variety of etiologies. Sperm DNA damage can be both a barrier to natural pregnancy and successful assisted reproductive technology (ART). The aim of this narrative review was to describe and highlight the effects of sperm DNA fragmentation and the most recent data on various treatment strategies to decrease sperm DNA damage. Finally, we proposed a management algorithm for couples undergoing ART with increased sperm DNA fragmentation.

Simulating nature in sperm selection for assisted reproduction

Sperm selection in the female reproductive tract (FRT) is sophisticated. Only about 1,000 sperm out of millions in an ejaculate reach the fallopian tube and thus have a chance of fertilizing an oocyte. In assisted reproduction techniques, sperm are usually selected using their density or motility, characteristics that do not reflect their fertilization competence and, therefore, might result in failure to fertilize the oocyte. Although sperm processing in in vitro fertilization (IVF) and intrauterine insemination (IUI) bypasses many of the selection processes in the FRT, selection by the cumulus mass and the zona pellucida remain intact. By contrast, the direct injection of a sperm into an oocyte in intracytoplasmic sperm injection (ICSI) bypasses all natural selection barriers and, therefore, increases the risk of transferring paternal defects such as fragmented DNA and genomic abnormalities in sperm to the resulting child. Research into surrogate markers of fertilization potential and into simulating the natural sperm selection processes has progressed. However, methods of sperm isolation - such as hyaluronic acid-based selection and microfluidic isolation based on sperm tactic responses - use only one or two parameters and are not comparable with the multistep sperm selection processes naturally occurring within the FRT. Fertilization-competent sperm require a panel of molecules, including zona pellucida-binding proteins and ion channel proteins, that enable them to progress through the FRT to achieve fertilization. The optimal artificial sperm selection method will, therefore, probably need to use a multiparameter tool that incorporates the molecular signature of sperm with high fertilization potential, and their responses to external cues, within a microfluidic system that can replicate the physiological processes of the FRT in vitro.

Nitric oxide-targeted protein phosphorylation during human sperm capacitation

Among many other molecules, nitric oxide insures the correct progress of sperm capacitation by mediating phosphorylation events. For a more comprehensive understanding of how this happens, we capacitated human spermatozoa from healthy men in the presence/absence of S-Nitrosoglutathione, a nitric oxide donor, two nitric oxide synthase inhibitors, N^G-Nitro-l-arginine Methyl Ester Hydrochloride and Aminoguanidine Hemisulfate salt and, finally, with/without l-Arginine, the substrate for nitric oxide synthesis, and/or human follicular fluid. When analyzing the phosphorylation of protein kinase A substrates and tyrosine residues, we particularly observed how the inhibition of nitric oxide synthesis affects certain protein bands (~ 110, ~ 87, ~ 75 and ~ 62 kD) by lowering their phosphorylation degree, even when spermatozoa were incubated with l-Arginine and/or follicular fluid. Mass spectrometry analysis identified 29 proteins in these species, related to: spermatogenesis, binding to the zona pellucida, energy and metabolism, stress response, motility and structural organization, signaling and protein turnover. Significant changes in the phosphorylation degree of specific proteins could impair their biological activity and result in severe fertility-related phenotypes. These findings provide a deeper understanding of nitric oxide’s role in the capacitation process, and consequently, future studies in infertile patients should determine how nitric oxide mediates phosphorylation events in the species here described.

Role of the sperm, oocyte, and embryo in recurrent pregnancy loss

Disorders affecting the sperm, oocyte, or embryo may cause a significant fraction of spontaneous miscarriages and cases of recurrent pregnancy loss (RPL). Altered chromosomal integrity of sperm and oocytes, which is highly dependent of the age of the mother, represents a major cause of miscarriage and in turn RPL. Avoiding transfers of abnormal embryos is possible with preimplantation genetic testing for aneuploidies. Chromosomal anomalies may also be caused by structural rearrangements of one or several chromosomes in either parents, a finding encountered in 12% of couples with RPL, including in those who have had one or several healthy babies. More than 40% of these chromosomal rearrangements are identifiable on regular karyotypes. When abnormal findings are made, preimplantation genetic testing for monogenic disorders allows selection of disease-free embryos. Finally, asymmetric inactivation of the X chromosome has been found more commonly in women with RPL, but no specific treatment is currently available.

Sperm Selection Technology in ART

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

Sperm binding to hyaluronan is an excellent predictor of Nili-Ravi buffalo bull fertility

This study reports the first evaluation of sperm hyaluronan binding assay (HBA) for predicting the fertility of Nili-Ravi buffalo bulls in relation to standard parameters of sperm quality. Cryopreserved semen doses of low (n = 6), medium (n = 3) and high fertility (n = 8) bulls based on their respective return rates were used. Significantly, more spermatozoa bound to hyaluronan from the most fertile bulls (57.15% ± 1.44) compared with medium (42.46% ± 1.08) and low fertility bulls (29.70% ± 0.78). A strongly positive correlation (r = .824, p < .01) was found between HBA and fertility that predicts a 67.9% variability (r²  = .679, p < .01) in fertility. HBA was also strongly positively correlated with sperm viability (r = .679, p < .01) followed by their live/dead ratio (r = .637, p < .01), uncapacitated spermatozoa (r = .631, p < .01), normal apical ridge (r = .459, p < .01), motility (r = .434, p < .01), mature spermatozoa with low residual histones (r = .364, p < .01), high plasma membrane integrity (r = .316, p < .01) and nonfragmented DNA levels (r = .236, p < .05). It was negatively correlated with spermatozoa having reacted acrosome (r = -.654, p < .01). A fertility model built using a combination of sperm HBA and either sperm livability or viability predicts, respectively, 86.1% (r²  = .861, p < .01) and 85.9% (r²  = .859, p < .01) variability in buffalo bull fertility. In conclusion, sperm HBA may prove to be a single robust predictor of Nili-Ravi buffalo bull fertility.

Magnetic Micromotors for Multiple Motile Sperm Cells Capture, Transport, and Enzymatic Release

An integrated system combining a magnetically-driven micromotor and a synthetized protein-based hyaluronic acid (HA) microflake is presented for the in situ selection and transport of multiple motile sperm cells (ca. 50). The system appeals for targeted sperm delivery in the reproductive system to assist fertilization or to deliver drugs. The binding mechanism between the HA microflake and sperm relies on the interactions between HA and the corresponding sperm HA receptors. Once sperm are captured within the HA microflake, the assembly is trapped and transported by a magnetically-driven helical microcarrier. The trapping of the sperm-microflake occurs by a local vortex induced by the microcarrier during rotation-translation under a rotating magnetic field. After transport, the microflake is enzymatically hydrolyzed by local proteases, allowing sperm to escape and finally reach the target location. This cargo-delivery system represents a new concept to transport not only multiple motile sperm but also other actively moving biological cargoes.

Changes in fertilization medium viscosity using hyaluronic acid impact bull sperm motility and acrosome status

The female reproductive tract, in particular the composition of the uterine and oviduct fluids, is responsible, at least in part, for triggering sperm cell modifications, essential for the acquisition of fertilization ability. Hyaluronic acid (HA) is a glycosaminoglycan present in these fluids, and its role in the fertilization process and sperm functionality is still barely understood. This work was designed to (a) determine the rheological characteristics of the fertilization medium by the addition of HA and (b) determine the HA influence on sperm motility and functional status. To that end, the in vitro fertilization medium was supplemented with 4 doses of HA (6, 60, 600 and 6,000 µg/ml) and analysed for viscosity and adhesion strength characteristics. Then, thawed semen from 6 bulls were incubated in these media and assessed at 4 different moments for morphological and functional parameters (plasma and acrosomal membrane integrities, mitochondrial membrane potential, capacitation, acrosomal reaction, and motility). The rheological evaluation showed that the addition of HA was able to increase both the viscosity and the adhesion strength of the fertilization medium, especially in the 6,000 µg/ml group in which the effect was more pronounced. No influence of HA could be observed on mitochondrial potential, and acrosomal and plasma membrane integrities. However, HA supplementation, at lower doses, led to an increase in the number of reacted sperm, as well as changes in motility parameters, with increase in the number of motile, rapid and progressive spermatozoa. In conclusion, the addition of HA alters the rheological properties of the fertilization medium and leads to the improvement of the properties related to sperm motility and capacitation, without compromising other functional aspects of the cell.

Effect of sperm selection using hyaluronan on fertilization and quality of cleavage-stage embryos in intracytoplasmic sperm injection (ICSI) cycles of couples with severe teratozoospermia

This study aimed to evaluate the effect of hyaluronan-selected/physiological intracytoplasmic sperm injection (PICSI) on fertilization and quality of cleavage-stage embryos in infertile couples with ≤1% of spermatozoa with normal strict morphology (severe teratozoospermia). Seventy-seven couples underwent PICSI between October 2017 and December 2018 (PICSI group), while 75 couples underwent conventional intracytoplasmic sperm injection (ICSI) between January 2016 and September 2017 (ICSI group). Good quality embryos (GQEs) were evaluated based on morphology. Patient and cycle characteristics were comparable between the PICSI and ICSI groups, except for age and anti-Müllerian hormone (AMH) level (38.4 ± 3.9 years vs. 36.3 ± 4.3 years, p = .002 and 2.06 ± 1.99 ng/mL vs. 2.97 ± 3.25 ng/mL, p = .040). The fertilization rate per oocyte inseminated and GQE rate were significantly higher in the PICSI group than in the ICSI group (82.7% vs. 71.7%, p ˂ .001 and 52.8% vs. 34.0%, p ˂ .001). Furthermore, the absence of GQEs was found to be lower in the PICSI group (13.0% vs. 30.7%, p = .008). Multivariate analysis adjusted for age and AMH level identified PICSI as an unfavorable and independent factor for the absence of GQEs (adjusted odds ratio, 0.333; 95% confidence interval, 0.125-0.890). PICSI seems to be superior to ICSI in terms of fertilization and embryo quality in couples with severe teratozoospermia.

Predictors of blastocyst formation rate in elective day 5 transfer cycle

This study aimed to investigate the factors affecting blastocyst formation rate. One hundred and seven fresh in vitro fertilisation (IVF) and elective day 5 blastocyst transfer cycles were selected. Univariate and multivariate analyses revealed that intracytoplasmic sperm injection (ICSI) (r = -.236, p = .014 vs. p = .005) was advantageous for blastocyst formation. In addition, the number of mature oocytes (r = -.274, p = .004 vs. p = .002) was a significant factor associated with blastocyst and good-quality blastocyst formation rates (p = .021, r = -.389). Both blastocyst and good-quality blastocyst formation rates were significantly higher with ICSI than with conventional insemination (65.0 ± 24.5% vs. 50.0 ± 21.2%, p = .012; 43.1 ± 22.8% vs. 30.9 ± 19.8%, p = .038, respectively). The number of mature oocytes appears to be the most important predictor of blastocyst formation rate. Additionally, ICSI fertilisation is superior to conventional insemination in terms of blastocyst formation rate.IMPACT STATEMENTWhat is already known on this subject? There are many advantages of blastocyst transfer cycle over cleavage transfer cycle, but there are no known routine selection criteria for the timing of embryo transfer. To date, the number of blastomeres, number of retrieved oocytes, quality of embryos and fertilisation method have been suggested as the important factors involved in blastocyst formation. However, the number of studies on this issue is limited, and some studies have shown conflicting results.What do the results of this study add? This study showed that the number of mature oocytes and ICSI fertilisation are the significant factors associated with blastocyst formation rate in elective day 5 transfer cycle.What are the implications of these findings for clinical practice and/or further research? This paper demonstrated that the number of mature oocytes and the fertilisation method should be considered before embryo transfer. Consideration of these factors would be meaningful in selecting patients who will be suitable for extended culture up to day 5.

The motility-based swim-up technique separates bull sperm based on differences in metabolic rates and tail length

Swim-up is a sperm purification method that is being used daily in andrology labs around the world as a simple step for in vitro sperm selection. This method accumulates the most motile sperm in the upper fraction and leaves sperm with low or no motility in the lower fraction. However, the underlying reasons are not fully understood. In this article, we compare metabolic rate, motility and sperm tail length of bovine sperm cells of the upper and lower fraction. The metabolic assay platform reveals oxygen consumption rates and extracellular acidification rates simultaneously and thereby delivers the metabolic rates in real time. Our study confirms that the upper fraction of bull sperm has not only improved motility compared to the cells in the lower fraction but also shows higher metabolic rates and longer flagella. This pattern was consistent across media of two different levels of viscosity. We conclude that the motility-based separation of the swim-up technique is also reflected in underlying metabolic differences. Metabolic assays could serve as additional or alternative, label-free method to evaluate sperm quality.

Advanced sperm selection techniques for assisted reproduction

BACKGROUND

Assisted reproductive technologies (ART) including in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI), combine gametes to enhance the probability of fertilisation and pregnancy. Advanced sperm selection techniques are increasingly employed in ART, most commonly in cycles utilising ICSI. Advanced sperm selection techniques are proposed to improve the chance that structurally intact and mature sperm with high DNA integrity are selected for fertilisation. Strategies include selection according to surface charge; sperm apoptosis; sperm birefringence; ability to bind to hyaluronic acid; and sperm morphology under ultra-high magnification. These techniques are intended to improve ART outcomes.

OBJECTIVES

To evaluate the effectiveness and safety of advanced sperm selection techniques on ART outcomes.

SEARCH METHODS

We conducted a systematic search of electronic databases (Cochrane Gynaecology and Fertility Group Specialised Register, CENTRAL via the Cochrane Register of Studies Online, MEDLINE, Embase, PsycINFO, Cumulative Index to Nursing and Allied Health Literature (CINAHL); trials registers (ClinicalTrials.gov, Current Controlled Trials, and the World Health Organization International Clinical Trials Registry Platform); conference abstracts (Web of Knowledge); and grey literature (OpenGrey) for relevant randomised controlled trials (RCTs). We handsearched the reference lists of included studies and similar reviews. The search was conducted in June 2018.

SELECTION CRITERIA

We included RCTs comparing advanced sperm selection techniques versus standard IVF, ICSI, or another technique. We excluded studies of intracytoplasmic morphologically selected sperm injection (IMSI), as they are subject to a separate Cochrane Review. Primary outcomes measured were live birth and miscarriage per woman randomly assigned. Secondary outcome measures included clinical pregnancy per woman randomly assigned. Secondary adverse events measured included miscarriage per clinical pregnancy and foetal abnormality.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility and risk of bias and extracted data. Any disagreements were resolved by consultation with a third review author. We consulted study investigators to resolve queries. Risk ratios (RRs) were calculated with 95% confidence intervals (CIs). We combined studies using a fixed-effect model. We evaluated the quality of the evidence using GRADE methods.

MAIN RESULTS

We included eight RCTs (4147 women). The quality of evidence ranged from very low to low. The main limitations were imprecision, performance bias, and attrition bias.Hyaluronic acid selected sperm-intracytoplasmic sperm injection (HA-ICSI) compared to ICSITwo RCTs compared the effects of HA-ICSI versus ICSI on live birth. The quality of the evidence was low. There may be little or no difference between groups: 25% chance of live birth with ICSI versus 24.5% to 31% with HA-ICSI (RR 1.09, 95% CI 0.97 to 1.23, 2903 women, I2 = 0%, low-quality evidence). Three RCTs reported on miscarriage. HA-ICSI may decrease miscarriage per woman randomly assigned: 7% chance of miscarriage with ICSI versus 3% to 6% chance with HA-ICSI (RR 0.61, 95% CI 0.45 to 0.83, 3005 women, I2 = 0%, low-quality evidence) and per clinical pregnancy: 20% chance of miscarriage with ICSI compared to 9% to 16% chance with HA-ICSI (RR 0.62, 95% CI 0.46 to 0.82, 1065 women, I2 = 0%, low-quality evidence). Four RCTs reported on clinical pregnancy. There may be little or no difference between groups: 37% chance of pregnancy with ICSI versus 34% to 40% chance with HA-ICSI (RR 1.00, 95% CI 0.92 to 1.09, 3492 women, I2 = 0%, low-quality evidence).HA-ICSI compared to SpermSlowOne RCT compared HA-ICSI to SpermSlow. The quality of the evidence was very low. We are uncertain whether HA-ICSI improves live birth compared to SpermSlow (RR 1.13, 95% CI 0.64 to 2.01, 100 women) or clinical pregnancy (RR 1.05, 95% CI 0.66 to 1.68, 100 women). We are uncertain whether HA-ICSI reduces miscarriage per woman (RR 0.80, 95% CI 0.23 to 2.81, 100 women) or per clinical pregnancy (RR 0.76, 95% CI 0.24 to 2.44, 41 women).Magnetic-activated cell sorting (MACS) compared to ICSIOne RCT compared MACS to ICSI for live birth; three reported clinical pregnancy; and two reported miscarriage. The quality of the evidence was very low. We are uncertain whether MACS improves live birth (RR 1.95, 95% CI 0.89 to 4.29, 62 women) or clinical pregnancy (RR 1.05, 95% CI 0.84 to 1.31, 413 women, I2 = 81%). We are also uncertain if MACS reduces miscarriage per woman (RR 0.95, 95% CI 0.16 to 5.63, 150 women, I2 = 0%) or per clinical pregnancy (RR 0.51, 95%CI 0.09 to 2.82, 53 women, I2=0)Zeta sperm selection compared to ICSIOne RCT evaluated Zeta sperm selection. The quality of the evidence was very low. We are uncertain of the effect of Zeta sperm selection on live birth (RR 2.48, 95% CI 1.34 to 4.56, 203 women) or clinical pregnancy (RR 1.82, 95% CI 1.20 to 2.75, 203 women). We are also uncertain if Zeta sperm selection reduces miscarriage per woman (RR 0.73, 95% CI 0.16 to 3.37, 203 women) or per clinical pregnancy (RR 0.41, 95% CI 0.10 to 1.68, 1 RCT, 62 women).MACS compared to HA-ICSIOne RCT compared MACS to HA-ICSI. This study did not report on live birth. The quality of the evidence was very low. We are uncertain of the effect on miscarriage per woman (RR 1.52, 95% CI 0.10 to 23.35, 78 women) or per clinical pregnancy (RR 1.06, 95% CI 0.07 to 15.64, 37 women). We are also uncertain of the effect on clinical pregnancy (RR 1.44, 95% CI 0.91 to 2.27, 78 women).

AUTHORS' CONCLUSIONS

The evidence suggests that sperm selected by hyaluronic acid binding may have little or no effect on live birth or clinical pregnancy but may reduce miscarriage. We are uncertain of the effect of Zeta sperm selection on live birth, clinical pregnancy, and miscarriage due principally to the very low quality of the evidence for this intervention. We are uncertain of the effect of the other selection techniques on live birth, miscarriage, or pregnancy.Further high-quality studies, including the awaited data from the identified ongoing studies, are required to evaluate whether any of these advanced sperm selection techniques can be recommended for use in routine practice.

Sperm selection methods in the 21st century

Natural sperm selection in humans is a rigorous process resulting in the highest quality sperm reaching, and having an opportunity to fertilize, the oocyte. Relative to other mammalian species, the human ejaculate consists of a heterogeneous pool of sperm, varying in characteristics such as shape, size, and motility. Semen preparation in assisted reproductive technologies (ART) has long been performed using either a simple swim-up method or density gradients. Both methodologies provide highly motile sperm populations; however neither replicates the complex selection processes seen in nature. A number of methods have now been developed to mimic some of the natural selection processes that exist in the female reproductive tract. These methods attempt to select a better individual, or population of, spermatozoa when compared to classical methods of preparation. Of the approaches already tested, platforms based upon sperm membrane markers, such as hyaluronan or annexin V, have been used to either select or deselect sperm with varied success. One technology that utilizes the size, motility, and other characteristics of sperm to improve both semen analysis and sperm selection is microfluidics. Here, we sought to review the efficacy of both available and emerging techniques that aim to improve the quality of the sperm pool available for use in ART.

Comparison of Conventional Slow Freeze versus Permeable Cryoprotectant-Free Vitrification of Abnormal Semen Sample: A Randomized Controlled Trial

Background:

The cryopreservation of semen samples by slow freezing remains as standard protocol. Recently, vitrification of spermatozoa was successfully reported with superior outcome. Till date, there is no randomized trial comparing the two different protocols.

Aim:

The aim of the present study is to evaluate the slow freezing with vitrification of the subfertile men spermatozoa to evaluate the progressive motility, vitality, and chromatin integrity.

Setting:

The study was conducted at University teaching hospital.

Design:

Study design involves randomized control trial.

Materials and Methods:

Twenty subfertile men with semen characteristics of severe oligoasthenozoospermia (SOA) and very SOA (VSOA) randomized to undergo slow freezing and vitrification protocol and cryopreserved at 1-month and 6-month storage interval, postthawed or warmed, samples were assessed for progressive motility, vitality, and hyaluronan binding. SPSS version 14 software was used for statistical analysis.

Results:

The SOA samples at 1 month revealed significantly higher motility (42% [22%–74%] vs. 7% [1%–13%]; P = 0.015) and vitality (57% [45%–78%] vs. 34.5% [27–42]; P < 0.001) following vitrification compared to slow-freeze method. For Very severe oligoasthenozoospermia (VSOA), the motility was significantly higher following vitrification (14.5% [2%–32%] vs. 2.5% [0%–4%]; P = 0.007). At 6 months, no statistically significant difference in motility was found between the two groups for Severe Oligoasthenozoospermia (SOA) samples (27% [13%–62%] vs. 8% [0%–11%]; P = 0.066), but motility was significantly higher following vitrification for VSOA samples (12.5% [3%–32%] vs. 2% [1%–5%]; P = 0.019). The hyaluronan-binding assay was comparable in both the groups at 6 months.

Conclusions:

The current study found the vitrification method involving the use of only nonpermeable cryoprotectants for cryopreservation of abnormal semen sample to be an effective alternative to the conventional slow-freeze technique.

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.

An efficiency comparison of different in vitro fertilization methods: IVF, ICSI, and PICSI for embryo development to the blastocyst stage from vitrified porcine immature oocytes

Background

Most studies carried out to evaluate recovery and development after porcine oocyte vitrification, reported better rates when cryopreserved in embryonic development stages or zygotes, but not in immature oocytes. For this reason, many studies are performed to improve immature oocyte vitrification protocols testing the use of different cryoprotectant concentrations, cooling devices, incubation times; but only a few of them have evaluated which fertilization procedure enhances blastocyst rates in vitrified oocytes. Therefore, this study was aimed to evaluate: 1) if the sperm selection with hyaluronic acid (HA) or polyvinylpyrrolidone (PVP) before injection could play a key role in increasing fertilization and blastocyst formation and 2) the embryo developmental ability and blastocyst production of porcine immature oocytes retrieved after vitrification-warming and co-cultured with granulosa cells during IVM, using different fertilization techniques: in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI) and conventional ICSI with hyaluronic acid (HA) sperm selection, known as physiological intracytoplasmic sperm injection (PICSI) and.

Results

Sperm selected with HA-PICSI displayed a higher percentage of live/acrosome reacted status compared to those in control and exposed to PVP. Higher dead/acrosome reacted rates were obtained after PVP exposure compared to control and HA. In oocytes, viability significantly decreased after IVM in vitrified oocytes. Besides, IVM rates were not different between control denuded oocytes cultured with granulosa cells (DO-GC) and vitrified oocytes. Regarding fertilization parameters, IVF showed higher percentages of total fertilization rate than those obtained by ICSI and PICSI. However, results demonstrate that PICSI fertilization increased the blastocysts formation rate in control DO-GC and vitrified oocytes compared to IVF and ICSI.

Conclusions

To achieve high blastocyst formation rates from vitrified GV oocytes, it is recommended that sperm should be selected with HA instead of PVP before injection since high viability and acrosome reaction rates were obtained. Also, PICSI fertilization was the best method to produce higher blastocyst rates compared to the IVF and ICSI procedures.

Knowledge gaps in male infertility: a reproductive endocrinology and infertility perspective

Reproductive research has moved forward at a remarkable pace. Some of these advances are the result of a separation between male and female specialties, allowing focused study in specific areas of the field. However, the different training programs between male and female fertility specialists has created an environment in which some discoveries are not put in the greater context of clinical care. At times, interventions have been measured against surrogate markers of outcome that may not impact the most meaningful outcome for patients—the delivery of a healthy neonate. For example, medical and surgical interventions that use changes in semen parameters may have a limited impact on the likelihood of achieving a live birth due to the limitations inherent in the semen analysis for predicting outcomes. Other commonly used tests, such as sperm DNA fragmentation assays provide promising biological plausibility to account for subfertility of some male partners. However, until well defined thresholds for predicting outcomes in different treatment scenarios are available, changes in sperm DNA fragmentation testing is not an adequate outcome for measuring the utility of interventions. The biggest limitation for these tests remains their analysis of bulk semen. Tests allowing interrogation of the reproductive competence of a given sperm, while allowing that sperm to be used in assisted reproductive technology procedures remain elusive. Progress toward reaching this end (whether by hyaluronic acid binding, IMSI, or Ramen spectroscopy) is underway, but much remains to be learned. Achieving testing and capture of individual sperm would better facilitate studies that measure the most meaningful outcome for patients and providers—the delivery of a healthy baby.

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.

Human sperm handling in intracytoplasmic sperm injection processes: In vitro studies on mouse oocyte activation, embryo development competence and sperm oxidation-reduction potential

Polyvinylpyrrolidone (PVP) and hyaluronic acid (HA) are routinely used in handling spermatozoa for intracytoplasmic sperm injection (ICSI). As there are still concerns about possible adverse effects on the embryo, this study investigated sperm handling in a mouse ICSI model to (i) evaluate oocyte activation after injection of spermatozoa selected for rotational or linear motion in PVP; (ii) assess the effect of sperm selection in PVP, HA and medium on oocyte activation; (iii) examine the effects of PVP and HA on parthenogenetic oocyte activation and embryo development; and (iv) assess the oxidation-reduction potential (ORP) of spermatozoa exposed to PVP, HA or medium. Oocyte activation was higher when spermatozoa exhibited rotational motion rather than linear motion (79% vs. 52%; p = .05). There was no difference in oocyte activation and embryo development after parthenogenetic oocyte activation after sperm injection using PVP, HA or medium-incubated spermatozoa. PVP-selected spermatozoa exhibited lower (p < .0001) ORP levels than using HA. Thus, results indicate that the sperm handling method and the type of medium used impact ICSI outcomes. Overall, sperm incubation in PVP, HA and medium yields similar outcomes with regard to oocyte activation and embryo development. However, PVP provides more antioxidative protection than HA and should therefore be preferred for sperm manipulation.

Strategies to improve fertilisation rates with assisted conception: a systematic review

Successful fertilisation is one of the key steps determining success of assisted conception. Various factors including sperm or oocyte pathology and environmental factors have a significant impact on fertilisation rates. This systematic review is aimed to evaluate the existing evidence about factors affecting fertilisation and strategies to improve fertilisation rates. A literature search was performed using Ovid MEDLINE ® (Jan 1950-April 2016), EMBASE (Jan 1950-April 2016), Ovid OLDMEDLINE ®, Pre-MEDLINE (Jan 1950-April 2016) and the Cochrane Library. Relevant key words were used to combine sets of results and a total 243 papers were screened. Only qualitative analysis was performed, as there was major heterogeneity in study design and methodology for quantitative synthesis. Factors affecting fertilisation were divided into sperm- and oocyte-related factors. The methods to improve fertilisation rates were grouped together based on the approach used to improve fertilisation rates. Optimising laboratory condition and procedural effects in techniques is associated with improved fertilisation rates. Various techniques are described to improve fertilisation rates including assisted oocyte activation, physiological intracytoplasmic sperm injection (PICSI) and intracytoplasmic morphologically selected sperm injection (IMSI). This review highlights the promising strategies under research to enhance fertilisation rates. Adequately powered multicentre randomised trials are required to evaluate these techniques before considering clinical application.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

Sperm DNA Fragmentation Index and Hyaluronan Binding Ability in Men from Infertile Couples and Men with Testicular Germ Cell Tumor

Objective. To investigate sperm DNA fragmentation and sperm functional maturity in men from infertile couples (IC) and men with testicular germ cell tumor (TGCT). Materials and Methods. Semen samples were collected from 312 IC men and 23 men with TGCT before unilateral orchiectomy and oncological treatment. The sperm chromatin dispersion test was performed to determine DNA fragmentation index (DFI) and the ability of sperm to bind with hyaluronan (HA) was assessed. Results. In comparison with the IC men, the men with TGCT had a higher percentage of sperm with fragmented DNA (median 28% versus 21%; p < 0.01) and a lower percentage of HA-bound sperm (24% versus 66%; p < 0.001). Normal results of both analyses were observed in 24% of IC men and 4% of men with TGCT. Negative Spearman's correlations were found between DFI and the percentage of HA-bound sperm in the whole group and in IC subjects and those with TGCT analyzed separately. Conclusions. Approximately 76% of IC men and 96% with TGCT awaiting orchiectomy demonstrated DNA fragmentation and/or sperm immaturity. We therefore recommend sperm banking after unilateral orchiectomy, but before irradiation and chemotherapy; the use of such a deposit appears to be a better strategy to obtain functionally efficient sperms.

HBA score in relation to donor semen profiles and live birth rates: a preliminary study

We sought to determine whether sperm donor selection could be improved by using the hyaluronan binding assay (HBA) score to predict live birth rates (LBRs) in donor insemination treatments. Thirty donor samples were included: five fresh samples to assess whether HBA score is affected by cryopreservation and 25 frozen samples from donors whose sperm gave rise to known live births, divided into three groups, with success rates ≥50%, <50-33% and <33%, to examine whether HBA score correlates with LBRs. Correlations with semen analysis parameters, as well as donor demographic factors, known causes of patient subfertility and/or the type of treatment provided were also assessed. There was no significant difference in the mean HBA score pre- and post-cryopreservation (p = 0.998) nor in the HBA score of the three different outcome groups (p = 0.89). HBA score was not significantly affected by other semen analysis parameters (r²=0.394, p = 0.127) or any of the other examined factors. This was the first study to investigate HBA score for cryopreserved donor samples with known LBRs. HBA score was not correlated with LBRs in this small pilot study. Larger studies are required to validate HBA score as a tool for sperm donor selection and predictor of LBRs.

Improving ICSI: A review from the spermatozoon perspective

Intracytoplasmic sperm injection (ICSI) is the most frequently applied method for fertilization making the process of identifying the perfect spermatozoon fundamental. Herein we offer a critical and thorough presentation on the techniques reported regarding (i) handling and preparing semen samples, (ii) identifying and 'fishing' spermatozoa, and (iii) improving key factors, such as motility for a successful ICSI practice. These approaches are suggested to make the process easier and more effective especially in atypical and challenging circumstances. Furthermore, we present an epigrammatic opinion-where appropriate-based upon our collective experience. Techniques such as intracytoplasmic morphologically selected sperm injection, hyaluronic binding, polarized light microscopy, and annexin V agent identification for comparing sperm cells and their chromatin integrity are analyzed. Moreover, for the demanding cases of total sperm immotility the use of the hypoosmotic swelling test, methylxanthines, as well as the option of laser assisted immotile sperm selection are discussed. Finally, we refer to the employment of myoinositol as a way to bioreactively improve ICSI outcome for oligoasthenoteratozoospermic men. The diversity and the constant development of novel promising techniques to improve ICSI from the spermatozoon perspective, is certainly worth pursuing. The majority of the techniques discussed are still a long way from being established in routine practices of the standard IVF laboratory. In most cases an experienced embryologist could yield the same results. Although some of the techniques show great benefits, there is a need for large scale multicenter randomized control studies to be conducted in order to specify their importance before suggesting horizontal application. Taking into consideration the a priori invasive nature of ICSI, when clinical application becomes a possibility we need to proceed with caution and ensure that in the pursuit for innovation we are not sacrificing safety and the balance of the physiological and biological pathways of the spermatozoon's dynamic.

ABBREVIATIONS

ICSI: intracytoplasmic sperm injection; IVF: in vitro fertilization; PGD: reimplantation genetic diagnosis; IVM: in vitro maturation; HCV/HIV: hepatitis C virus/human immunodeficiency virus; IMSI: intracytoplasmic morphologically selected sperm injection; DGC: density gradient centrifugations; S-U: swim-up; ART: assisted reproduction technology; IUI: intrauterine insemination; PVP: polyvinylpyrrolidone; HA: hyaluronic acid; MSOME: motile sperm organelle morphology examination; ZP: zona pellucida; MACS: magnetic activation cell sorting; HOST: hypo-osmotic swelling test; TESE: testicular sperm extraction; MMP: mitochondrial membrane potential; OAT: oligoasthenoteratozoospermic.

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

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

The ubiquitous hyaluronan: Functionally implicated in the oviduct?

Hyaluronan (hyaluronic acid) is a simple, nonantigenic, nonsulfated glycosaminoglycan present everywhere in the extracellular compartments of the body. Noteworthy, it is highly conserved phylogenetically, from sauropsida to mammals; and plays a plethora of roles from embryonic/fetal development to adult physiological and pathological events, including tumor development. In reproduction, hyaluronan has proven related to initial events as sperm survival, buildup of the sperm reservoir in the oviduct, regulation of sperm capacitation, and prefertilization to later participate in embryo, fetal, and placental development. Synthesis, binding (via the CD44 membrane receptor), and degradation of hyaluronan occur in male and female genital organs, the oviduct being no exception. This review discusses our current knowledge on roles of this ubiquitous glycosaminoglycan on the survival of immunologically foreign spermatozoa in the pig oviduct, a relevant event for fertility. During preovulatory storage in the functional tubal sperm reservoir, spermatozoa are entrapped in a mucus-like tubal fluid. This fluid contains fluctuating levels of hyaluronan, which is synthesized by the lining epithelium by hyaluronan synthase 3. Both hyaluronan and its CD44 receptor are particularly evident in the deep mucosal furrows of the sperm reservoir, in which most spermatozoa are embedded in; kept alive, uncapacitated but also undetected by the immune system of the female. Hyaluronan is also present in the seminal plasma, and evidence points toward an involvement of hyaluronan and its receptor in the local (tubal and possibly uterine) production of antiinflammatory cytokines, such as interleukin-10, pertaining maternal immune tolerance of these foreign cells.

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.

Use of hyaluronic acid for sperm immobilisation and selection before intracytoplasmic sperm injection: A systematic review and meta-analysis

AIM: To appraise critically the published randomised controlled trials (RCTs) reporting on the effectiveness of using hyaluronic acid (HA) for sperm immobilisation and selection before intracytoplasmic sperm injection (ICSI).

METHODS: Two authors used the PICO Method in order to perform a comprehensive literature search of the standard medical databases in June 2015. Data from the included studies was extracted independently by two authors using a predefined pro-forma. Review Manager (RevMan) was used to calculate the combined outcomes where multiple studies contributed with their results. Risk ratio (RR) with a 95%CI using the Mantel-Haenszel method was calculated for binary data variables. Heterogeneity was measured using the χ² test and quantified using I². In case of substantial heterogeneity (P < 0.10 for χ² test or I² > 50%) the combined outcome was calculated using the random effects model. The results from the meta-analysis were displayed as forest plots. The guideline of the Cochrane Collaboration was used to assess the risk of bias and it was illustrated as a risk of bias graph.

RESULTS: The systematic literature search identified 166 different studies related to sperm immobilisation and selection for ICSI. Eleven RCTs involving 13719 oocyte intracytoplasmatic injections with sperm immobilised and selected using HA or polyvinylpyrrolidone (PVP) were included in this systematic review and meta-analysis. There was low heterogeneity among the included trials (χ² = 16.86, df = 11, P = 0.11; I² = 35%). There was no statistical difference between HA and PVP groups in terms of fertilisation rate (RR = 1.01; 95%CI: 0.99-1.03; z = 0.75; P = 0.45), good embryos rate (RR = 1.01; 95%CI: 0.96-1.06; z = 0.30; P = 0.76), live birth rate (RR = 1.15; 95%CI: 0.86-1.54; z = 0.92; P = 0.36), clinical pregnancy rate (RR = 1.04; 95%CI: 0.92-1.17; z = 0.62; P = 0.53) and implantation rate (RR = 1.17; 95%CI: 0.94-1.46; z = 0.40; P = 0.16). The quality of most of the included studies was moderate to poor because of unclear randomisation technique, inadequate allocation concealment and blinding.

CONCLUSION: This systematic review and meta-analysis provides evidence of similar efficiency between using HA or PVP for sperm immobilisation and selection before ICSI.

Sperm selection in natural conception: what can we learn from Mother Nature to improve assisted reproduction outcomes?

BACKGROUND

In natural conception only a few sperm cells reach the ampulla or the site of fertilization. This population is a selected group of cells since only motile cells can pass through cervical mucus and gain initial entry into the female reproductive tract. In animals, some studies indicate that the sperm selected by the reproductive tract and recovered from the uterus and the oviducts have higher fertilization rates but this is not a universal finding. Some species show less discrimination in sperm selection and abnormal sperm do arrive at the oviduct. In contrast, assisted reproductive technologies (ART) utilize a more random sperm population. In this review we contrast the journey of the spermatozoon in vivo and in vitro and discuss this in the context of developing new sperm preparation and selection techniques for ART.

METHODS

A review of the literature examining characteristics of the spermatozoa selected in vivo is compared with recent developments in in vitro selection and preparation methods. Contrasts and similarities are presented.

RESULTS AND CONCLUSIONS

New technologies are being developed to aid in the diagnosis, preparation and selection of spermatozoa in ART. To date progress has been frustrating and these methods have provided variable benefits in improving outcomes after ART. It is more likely that examining the mechanisms enforced by nature will provide valuable information in regard to sperm selection and preparation techniques in vitro. Identifying the properties of those spermatozoa which do reach the oviduct will also be important for the development of more effective tests of semen quality. In this review we examine the value of sperm selection to see how much guidance for ART can be gleaned from the natural selection processes in vivo.