Clinical application of sperm-oocyte interaction tests in in vitro fertilization--embryo transfer and intracytoplasmic sperm injection programs

Sperm Selection Using Zona Pellucida-Binding Enhanced Embryo Morphokinetic and Clinical Outcomes in ICSI: A Sibling Oocytes Study

The objective was to investigate the embryo morphokinitics using a time-lapse monitoring (TLM) system and assessment of clinical outcomes following intracytoplasmic sperm injection (ICSI) with zona pellucida (ZP)-bound sperm selection and conventional methods. A total of 371 metaphase II (MII) oocytes from 50 ICSI cycles were studied. Sibling oocytes were randomly divided into control (n = 199) and ZP-bound group (n = 172). All resulting zygotes were cultured and monitored in the TLM system up to Day 3 after ICSI. Fertilization rate, early embryo development, and clinical outcomes were evaluated. No significant differences were found in fertilization rate, time-lapse qualitative and quantitative measures, pronuclear fading time (PNF) t2, t3, t4, t5, t6, and t7 (times of cleavage to 2, 3, 4, 5, 6, and 7 cells), respectively. However, the t8 (time of cleavage to eight cells) and cc3 (duration of third cell cycle) revealed a significant difference between control and ZP-bound groups (p < .05). A significant difference between the two groups (p < .05) in the rates of Grade A embryos (according to Basile algorithm), chemical pregnancy, clinical pregnancy, and implantation was observed. Sperm selection using biological materials, such as ZP, improved both embryo quality and pregnancy outcomes, despite not affecting the early embryo development and morphokinetic parameters up to t8. This prospective randomized sibling oocyte trial was registered in October 2020 to January 2022 (IRCT20200705048021N1).

The Sperm DNA Fragmentation Assay with SDF Level Less Than 15% Provides a Useful Prediction for Clinical Pregnancy and Live Birth for Women Aged under 40 Years

This retrospective cohort study was conducted on 1148 males who presented along with their partners for infertility management at the PIVET Medical Centre between 2013 and 2022 and had a sperm DNA fragmentation (SDF) assay performed by Halosperm, thereafter participating in 1600 assisted reproductive technology (ART) cycles utilising one of three modalities, namely, IVF-Only, ICSI-Only or IVF-ICSI Split cycles. The outcomes from the ART cycles were then analysed as two groups based on SDF levels <15% and ≥15%. The study showed the unadjusted fertilization rates were not different between the groups, neither across the four female age ranges. However, when the fertilization rates were adjusted for the mature oocytes (metaphase-II oocytes), there was a highly significant difference in fertilization rates in favour of the group with SDF levels < 15% where the women were in the younger age grouping of <35 years (78.4% vs. 73.0%; p < 0.0001). Overall, there was no difference in the rates of blastocyst development nor clinical pregnancy rates between the two SDF groups, but there was a significantly higher pregnancy rate for the younger women (<35 years) with the group of SDF level < 15% (44.1% vs. 37.4%; p = 0.04). Similarly, there was no difference in the miscarriage rates overall with respect to SDF groups, and no clear picture could be deciphered among the women's age groups. With respect to cumulative live births, this reflected the pregnancy rates with no overall difference between the two SDF groups, but there was a significantly higher cumulative live birth rate for women <35 years where the SDF level was <15% (38.6% vs. 28.6%; p < 0.01). Among the three modalities, the highest cumulative live birth rate occurred within the group with SDF level < 15%, being highest with the IVF mode, particularly for women aged <40 years (43.0% vs. 37.7% for IVF-ICSI Split and 27.9% for ICSI; p = 0.0002), noting that the IVF case numbers were disproportionately low.

The life history of Drosophila sperm involves molecular continuity between male and female reproductive tracts

In species with internal fertilization, sperm spend an important part of their lives within the female. To examine the life history of the sperm during this time, we used semiquantitative proteomics and sex-specific isotopic labeling in fruit flies to determine the extent of molecular continuity between male and female reproductive tracts and provide a global catalog of sperm-associated proteins. Multiple seminal fluid proteins and female proteins associate with sperm immediately after mating. Few seminal fluid proteins remain after long-term sperm storage, whereas female-derived proteins constitute one-fifth of the postmating sperm proteome by then. Our data reveal a molecular “hand-off” from males to females, which we postulate to be an important component of sperm–female interactions.

Interactions between sperm and the female reproductive tract (FRT) are critical to reproductive success and yet are poorly understood. Because sperm complete their functional maturation within the FRT, the life history of sperm is likely to include a molecular “hand-off” from males to females. Although such intersexual molecular continuity is likely to be widespread among all internally fertilizing species, the identity and extent of female contributions are largely unknown. We combined semiquantitative proteomics with sex-specific isotopic labeling to catalog the posttesticular life history of the sperm proteome and determine the extent of molecular continuity between male and FRTs. We show that the Drosophila melanogaster sperm proteome undergoes substantial compositional changes after being transferred to the FRT. Multiple seminal fluid proteins initially associate with sperm, but most become undetectable after sperm are stored. Female-derived proteins also begin to associate with sperm immediately after mating, and they comprise nearly 20% of the postmating sperm proteome following 4 d of storage in the FRT. Female-derived proteins that associate with sperm are enriched for processes associated with energy metabolism, suggesting that female contributions support sperm viability during the prolonged period between copulation and fertilization. Our research provides a comprehensive characterization of sperm proteome dynamics and expands our understanding of the critical process of sperm–FRT interactions.

Toll-like Receptor 2 is Involved in Calcium Influx and Acrosome Reaction to Facilitate Sperm Penetration to Oocytes During in vitro Fertilization in Cattle

Cumulus cells of ovulated cumulus-oocyte complexes (COCs) express Toll-like receptor 2 (TLR2), pathogen recognition receptors, to recognize and react to sperm signals during fertilization. Sperm also express TLR2, but its contribution to the sperm-oocytes crosstalk is still unclear. Here, we adapted the in vitro fertilization (IVF) model to characterize the potential relevance of sperm TLR2 in sperm-oocytes interactions during fertilization in bovine. The IVF results showed that the ligation of sperm TLR2 with its specific antagonist/agonist resulted in down/up-regulation of the cleavage and blastocyst rates either in COCs or cumulus-free oocytes, but not in zona pellucida (ZP)-free oocytes. The computer-assisted sperm analysis (CASA) system revealed that sperm motility parameters were not affected in TLR2 antagonist/agonist-treated sperm. However, fluorescence imaging of sperm-ZP interactions revealed that the blockage or activation of the TLR2 system in sperm reduced or enhanced both binding and penetration abilities of sperm to ZP compared to control, respectively. Flow cytometrical analysis of acrosome reaction (AR) demonstrated that the TLR2 system adjusted the occurrence of AR in ZP-attached sperm, suggesting that sperm TLR2 plays physiological impacts on the sperm-oocyte crosstalk via regulating ZP-triggered AR in sperm. Given that calcium (Ca²⁺) influx is a pre-requisite step for the induction of AR, we investigated the impact of the TLR2 system on the ionophore A23187-induced Ca²⁺ influx into sperm. Notably, the exposure of sperm to TLR2 antagonist/agonist reduced/increased the intracellular Ca²⁺ level in sperm. Together, these findings shed new light that the TLR2 system is involved in sperm AR induction which enables sperm to penetrate and fertilize oocytes during the fertilization, at least in vitro, in cows. This suggests that sperm possibly developed a quite flexible sensing mechanism simultaneously against pathogens as well as COCs toward fertilization with the same TLR2 of the innate immune system.

Development a nomogram to predict fertilisation rate of infertile males with borderline semen by using semen parameters combined with AMH and INHB

The sperm quality of some males is in a critical state, making it hard for clinicians to choose the suitable fertilisation methods. This study aimed to develop an intelligent nomogram for predicting fertilisation rate of infertile males with borderline semen. 160 males underwent in vitro fertilisation (IVF), 58 of whom received rescue ICSI (R‐ICSI) due to fertilisation failure (fertilisation rate of IVF ≤30%). A least absolute shrinkage and selection operator (LASSO) regression analysis identified sperm concentration, progressively motile spermatozoa (PMS), seminal plasma anti‐Müllerian hormone (spAMH), seminal plasma inhibin (spINHB), serum AMH (serAMH) and serum INHB (serINHB) as significant predictors. The nomogram was plotted by multivariable logistic regression. This nomogram‐illustrated model showed good discrimination, calibration and clinical value. The area under the receiver operating characteristic curve (AUC) of the nomogram was 0.762 (p < .001). Calibration curve and Hosmer–Lemeshow test (p = .5261) showed good consistency between the predictions of the nomogram and the actual observations, and decision curve analysis showed that the nomogram was clinically useful. This nomogram may be useful in predicting fertilisation rate, mainly focused on new biomarkers, INHB and AMH. It could assist clinicians and laboratory technicians select appropriate fertilisation methods (IVF or ICSI) for male patients with borderline semen.

Participation of the inositol 1,4,5-trisphosphate-gated calcium channel in the zona pellucida- and progesterone-induced acrosome reaction and calcium influx in human spermatozoa

The acrosome reaction is a prerequisite for fertilization, and its signaling pathway has been investigated for decades. Regardless of the type of inducers present, the acrosome reaction is ultimately mediated by the elevation of cytosolic calcium. Inositol 1,4,5-trisphosphate-gated calcium channels are important components of the acrosome reaction signaling pathway and have been confirmed by several researchers. In this study, we used a novel permeabilization tool BioPORTER^® and first demonstrated its effectiveness in spermatozoa. The inositol 1,4,5-trisphosphate type-1 receptor antibody was introduced into spermatozoa by BioPORTER^® and significantly reduced the calcium influx and acrosome reaction induced by progesterone, solubilized zona pellucida, and the calcium ionophore A23187. This finding indicates that the inositol 1,4,5-trisphosphate type-1 receptor antibody is a valid inositol 1,4,5-trisphosphate receptor inhibitor and provides evidence of inositol 1,4,5-trisphosphate-gated calcium channel involvement in the acrosome reaction in human spermatozoa. Moreover, we demonstrated that the transfer of 1,4,5-trisphosphate into spermatozoa induced acrosome reactions, which provides more reliable evidence for this process. In addition, by treating the spermatozoa with inositol 1,4,5-trisphosphate/BioPORTER^® in the presence or absence of calcium in the culture medium, we showed that the opening of inositol 1,4,5-trisphosphate-gated calcium channels led to extracellular calcium influx. This particular extracellular calcium influx may be the major process of the final step of the acrosome reaction signaling pathway.

ICSI Versus Conventional IVF in Women Aged 40 Years or More and Unexplained Infertility: A Retrospective Evaluation of 685 Cycles with Propensity Score Model

This study compared the cumulative live birth rates following Intracytoplasmic sperm injection (ICSI) versus conventional in vitro fertilization (cIVF) in women aged 40 years or more and unexplained infertility. A cohort of 685 women undergoing either autologous conventional IVF or ICSI was retrospectively analyzed. The effects of conventional IVF or ICSI procedure on cumulative pregnancy and live birth rates were evaluated in univariate and in multivariable analysis. In order to reduce potential differences between women undergoing either IVF or ICSI and to obtain unbiased estimation of the treatment effect, propensity score was estimated. ICSI was performed in 307 couples (ICSI group), whereas cIVF was performed in 297 couples (cIVF group), resulting in 45 and 43 live deliveries, respectively. No differences were observed in morphological embryo quality, in the number of cleavage stage embryos, in the number of transferred embryos, and in the number of vitrified embryos. As for the clinical outcome, no differences were observed in pregnancy rate, cumulative pregnancy rate, live birth rate, cumulative live birth rate, and abortion rate. The present results suggest that ICSI is not associated with increased likelihood of a live birth for unexplained, non-male factor infertility, in women aged 40 years or more.

Should ICSI be implemented during IVF to all advanced-age patients with non-male factor subfertility?

BACKGROUD

In order to maximize In vitro fertilization (IVF) success rates in advanced- age patients, it has been suggested to favor the use of intracytoplasmic sperm injection (ICSI) over conventional insemination (CI), with the notion that ICSI would serve as a tool to overcome interference in sperm oocyte interaction and sperm oocyte penetration issues that can be related to maternal age and are not due to sperm abnormalities. We therefore aim to evaluate the role of ICSI in the treatment of non-male factor infertile patients aged ≥35 in terms of fertilization and top-quality embryo rates.

METHODS

In this retrospective cohort study, data were collected and analyzed for all patients with non-male factor infertility, aged ≥35 treated, undergoing their first IVF cycle attempt with 6 or more oocytes yield, in whom a 50% ICSI-CI division was performed.

RESULTS

Five hundreds and four oocytes were collected from 52 eligible patients. Overall, 245 oocytes underwent ICSI and 259 oocytes underwent CI. The fertilization rate was 71.0% following ICSI, compared to 50.1% in the CI treated oocytes (P < 0.001). The top quality embryo rate was 62.8% following ICSI compared to 45.5% following CI (P < 0.001). Subdividing the study population to two age groups revealed that the above differences remained significant in patients aged 35-39 yrs., whereas in those aged 40-45 yrs., the differences were non-significant but still inclined in favor of ICSI.

CONCLUSIONS

This study favors the use of ICSI in the older IVF population in order to increase both the fertilization rate and the number of top quality embryos that result per IVF cycle. Further studies are needed to establish our observations and use ICSI as the preferred approach to overcome egg sperm abnormal interactions related to advanced maternal age.

Sperm function tests in clinical practice

Conventional semen analysis solely is not completely adequate to predict pregnancy outcomes. Therefore, advanced sperm function tests have been developed and introduced to clinical practice. These tests use different methods and techniques to evaluate different stages of fertilization steps. In this review, we reported some commonly used sperm function tests: sperm penetration assay, sperm-zona pellucida binding test (hemizona assay), acrosomal reaction test, hyaluronan binding test, hypo-osmotic swelling test, magnetic-activated cell sorting and zeta sperm selection. We discussed the literature concerning these tests, the utilization techniques and also purpose and mechanism of each test. We emphasized the importance of sperm function tests in predicting in vitro fertilization and pregnancy outcomes and in the management of infertile couples and also the limitations of these tests. Along with improvements in molecular biology techniques, we believe that more applicative and beneficial tests will be developed in the near future.

Validation of a laboratory-developed test of human sperm capacitation

Sperm must undergo capacitation to become fertilization competent. Here we validated that monosialotetrahexosylganglioside (GM1 ) localization patterns, which were assessed in the Cap-Score™ Sperm Function Test, reflect a capacitated state in human sperm. First, we defined patterns representing sperm that do or do not respond to stimuli for capacitation. Sperm with "capacitated" patterns had exposed acrosomal carbohydrates and underwent acrosome exocytosis in response to calcium ionophore (A23187). Precision was evaluated by percent change of the Cap-Score measured for 50, 100, 150, and 200 sperm. Changes of 11%, 6%, and 5% were observed (n ≥ 23); therefore, we counted ≥150 sperm per condition. Variance within and between readers was evaluated using 20 stitched image files generated from unique ejaculates. Two trained readers randomly resampled each image 20 times, reporting an average standard deviation of 3 Cap-Score units and coefficient of variation of 13% when rescoring samples, with no difference between readers. Semen liquefaction times ≤2 hr and mechanical liquefaction with Pasteur or wide-orifice transfer pipettes did not alter Cap-Score values. However, liquefaction with chymotrypsin (p = 0.002) and bromelain (p = 0.049) reduced response to capacitating stimuli and induced membrane damage, while counterintuitively improving sperm motility. Together, these data validate the Cap-Score assay for the intended purpose of providing information on sperm capacitation and male fertility. In addition to its clinical utility as a diagnostic tool, this test of sperm function can reveal the impact of common practices of semen handling on the ability of sperm to respond to capacitation stimuli.

Cytotoxic and Genotoxic Effects of Acephate on Human Sperm

Extensive use of organophosphorus pesticides (OPs) could alter semen quality and sperm DNA at different stages of spermatogenesis. Acephate is a highly toxic extensively used OP and, therefore, we aimed to evaluate the effects of acephate on human semen quality and sperm DNA integrity. Sperm collected from healthy males were exposed to 0, 50, 100, and 200 μg/mL of acephate and incubated for 1 h, 2 h, and 3 h. Subsequently, sperm motility, vitality, functional integrity of plasma membrane, sperm capacitation, and DNA damage were examined. Result showed a significant decline of the motility at 100 μg/mL after 3 h and with 200 μg/mL after 1 h, 2 h, and 3 h. Viability was significantly reduced at 200 μg/mL after 2 h and 3 h. Functional integrity was significantly affected at 100 μg/mL after 3h and in 200 μg/mL dose after 2 h and 3h. Similarly, sperm capacitation was significantly affected at 200 μg/mL after 1 h, 2 h, and 3 h and at 100 μg/mL at 3 h. DNA damage was significantly increased only in 200 μg/mL dose after 3 h. The study suggests that exposure to acephate may result in alterations of sperm structure and function thus contributing towards deteriorating in human semen quality triggering infertility.

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

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

Obese father's metabolic state, adiposity, and reproductive capacity indicate son's reproductive health

OBJECTIVE

To determine whether dietary and exercise regimes in obese males can provide a novel intervention window for improving the reproductive health of the next generation.

DESIGN

Experimental animal study.

SETTING

University research facilities.

ANIMAL(S)

C57BL6 male and female mice.

INTERVENTION(S)

Mice were fed a control diet (6% fat) or high-fat diet (21% fat) for 9 weeks. After the initial feeding, high-fat-diet males were allocated to diet and/or exercise interventions for a further 9 weeks. After intervention males were mated with females fed standard chow (4% fat) before and during pregnancy.

MAIN OUTCOME MEASURE(S)

F1 sperm motility, count, morphology, capacitation, mitochondrial function, and sperm binding and weight of reproductive organs.

RESULT(S)

Our primary finding was that diet intervention alone in founders improved offspring sperm motility and mitochondrial markers of sperm health (decreased reactive oxygen species and mitochondrial membrane potential), ultimately improving sperm binding. Sperm binding and capacitation was also improved in F1 males born to a combined diet and exercise intervention in founders. Founder sperm parameters and metabolic measures as a response to diet and/or exercise (i.e., lipid/glucose homeostasis, sperm count and morphology) correlated with offspring's sperm function, independent of founder treatment. This implicates paternal metabolic and reproductive status in predicting male offspring's reproductive function.

CONCLUSION(S)

This is the first study to show that improvements to both metabolic (lipids, glucose and insulin sensitivity) and reproductive function (sperm motility and morphology) in obese fathers via diet and exercise interventions can improve subsequent reproductive health in offspring.

Unexplained male infertility: diagnosis and management

Unexplained male infertility is a diagnosis reserved for men in whom routine semen analyses results are within normal values and physical as well as endocrine abnormalities were ruled out. In addition to erectile problems and coital factors, immunologic causes and sperm dysfunction may contribute to such condition. New etiologies of unexplained male infertility include low level leukocytospermia and mitochondrial DNA polymerase gene polymorphism. Contemporary andrology may reveal cellular and sub-cellular sperm dysfunctions which may explain subfertility in such cases, thus aiding the clinician to direct the further work-up, diagnosis and counseling of the infertile male. The objective of this article is to highlight the concept of unexplained male infertility and focuses on the diagnosis and treatment of this condition in the era of modern andrology and assisted reproductive techniques. Extensive literature review was performed using the search engines: Pubmed, Science-direct, Ovid and Scopus.

Inhibition of ovine in vitro fertilization by anti-Prt antibody: hypothetical model for Prt/ZP interaction

BACKGROUND

The impact of prion proteins in the rules that dictate biological reproduction is still poorly understood. Likewise, the role of prnt gene, encoding the prion-like protein testis specific (Prt), in ram reproductive physiology remains largely unknown. In this study, we assessed the effect of Prt in ovine fertilization by using an anti-Prt antibody (APPA) in fertilization medium incubated with spermatozoa and oocytes. Moreover, a computational model was constructed to infer how the results obtained could be related to a hypothetical role for Prt in sperm-zona pellucida (ZP) binding.

METHODS

Mature ovine oocytes were transferred to fertilization medium alone (control) or supplemented with APPA, or pre-immune serum (CSerum). Oocytes were inseminated with ovine spermatozoa and after 18 h, presumptive zygotes (n=142) were fixed to evaluate fertilization rates or transferred (n=374) for embryo culture until D6-7. Predicted ovine Prt tertiary structure was compared with data obtained by circular dichroism spectroscopy (CD) and a protein-protein computational docking model was estimated for a hypothetical Prt/ZP interaction.

RESULTS

The fertilizing rate was lower (P=0.006) in APPA group (46.0+/-6.79%) when compared to control (78.5+/-7.47%) and CSerum (64.5+/-6.65%) groups. In addition, the cleavage rate was higher (P<0.0001) in control (44.1+/-4.15%) than in APPA group (19.7+/-4.22%). Prt CD spectroscopy showed a 22% alpha-helical structure in 30% (m/v) aqueous trifluoroethanol (TFE) and 17% alpha in 0.6% (m/v) TFE. The predominant alpha-helical secondary structure detected correlates with the predicted three dimensional structure for ovine Prt, which was subsequently used to test Prt/ZP docking. Computational analyses predicted a favorable Prt-binding activity towards ZP domains.

CONCLUSIONS

Our data indicates that the presence of APPA reduces the number of fertilized oocytes and of cleaved embryos. Moreover, the CD analysis data reinforces the predicted ovine Prt trend towards an alpha-helical structure. Predicted protein-protein docking suggests a possible interaction between Prt and ZP, thus supporting an important role for Prt in ovine fertilization.

The use of genomics, proteomics, and metabolomics in identifying biomarkers of male infertility

Although male factors account for approximately 50% of all infertility, the mechanisms underlying their origin are unknown. Currently, clinicians rely primarily on semen analyses to predict male reproductive potential and chart treatment success. Even when invasive procedures are performed, the causes of male factor infertility frequently remain elusive. Recently, the advent of new technologies has spurred the search for novel male infertility biomarkers, and the detection of genes, proteins, or metabolites unique to the infertile male holds much promise. The concept that a cost-effective, noninvasive, and accurate set of biomarkers can be identified to diagnose male factor infertility is tantalizing. This review focuses on the various methodologies used in the discovery of novel biomarkers along with their findings. Specific attention is paid to recent advances in the fields of genetics, proteomics, and metabolomics.

Defective protein kinase A and C pathways are common causes of disordered zona pellucida (ZP)--induced acrosome reaction in normozoospermic infertile men with normal sperm-ZP binding

OBJECTIVE

To determine association between defective protein kinases C (PKC) and A (PKA) and disordered zona pellucida (ZP)-induced acrosome reaction (DZPIAR) in normozoospermic infertile men with normal sperm-ZP binding.

DESIGN

Sperm from DZPIAR infertile men were treated without (control) or with (test) phorbol myristate acetate (PMA, PKC activator) or dibutyryl cyclic AMP (dbcAMP, PKA activator) under in vitro standard culture condition. The ZP-induced AR was assessed and compared between control and test.

SETTING

Public and private hospital-based clinical assisted reproduction technology (ART) centers.

PATIENT(S)

A total of 51 DZPIAR infertile men were involved in this study.

INTERVENTION(S)

None.

MAIN OUTCOMES MEASURE(S)

Sperm-ZP binding and the ZP-induced IAR.

RESULT(S)

Both PMA and dbcAMP enhanced ZP-induced AR up to a normal level (≥25%) in some subjects with DZPIAR: 29 (57%) with PMA and 27 (53%) with dbcAMP. Overall 35 (69%) had the ZP-induced AR enhanced to normal by PMA or dbcAMP but 16 (31%) had little or no response to either agent. Fourteen men responded to the two activators differently: 8 effective only with PMA and 6 effective only with dbcAMP.

CONCLUSION(S)

Defective upstream of PKC and PKA pathways are highly associated with disordered ZPIAR in normozoospermic infertile men with normal sperm-ZP binding.

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

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

Zona pellucida-induced acrosome reaction in human spermatozoa is potentiated by glycodelin-A via down-regulation of extracellular signal-regulated kinases and up-regulation of zona pellucida-induced calcium influx

BACKGROUND

Glycodelin-A interacts with spermatozoa before fertilization, but its role in modulating sperm functions is not known. Zona pellucida-induced acrosome reaction is crucial to fertilization and its dysfunction is a cause of male infertility. We hypothesized that glycodelin-A, a glycoprotein found in the female reproductive tract, potentiates human spermatozoa for zona pellucida-induced acrosome reaction.

METHODS

Glycodelin isoforms were immunoaffinity purified. The sperm intracellular cAMP concentration, protein kinase-A (PKA) and extracellular signal-regulated kinase (ERK) activities, and intracellular calcium were measured by ELISA, kinase activity assay kits and Fluo-4AM technique, respectively. The phosphorylation of inositol 1,4,5-trisphosphate type-1 receptor (IP3R1) mediated by ERK was determined by western blotting. Zona pellucida-induced acrosome reaction was detected by Pisum sativum staining.

RESULTS

Pretreatment of spermatozoa with glycodelin-A significantly up-regulated adenylyl cyclase/PKA activity and down-regulated the activity of ERK and its phosphorylation of IP3R1, thereby enhancing zona pellucida-induced calcium influx and zona pellucida-induced acrosome reaction. Glycodelin-F or deglycosylated glycodelin-A did not have these actions. Treatment of spermatozoa with a protein kinase inhibitor abolished the priming activity of glycodelin-A, whilst ERK pathway inhibitors mimic the stimulatory effect of glycodelin-A on zona pellucida-induced acrosome reaction.

CONCLUSIONS

Glycodelin-A in the female reproductive tract sensitizes spermatozoa for zona pellucida-induced acrosome reaction in a glycosylation-specific manner through activation of the adenylyl cyclase/PKA pathway, suppression of extracellular signal-regulated kinase activation and up-regulation of zona pellucida-induced calcium influx. The action of glycodelin-A may be important in vivo to ensure full responsiveness of human spermatozoa to the zona pellucida.

Separate and combined effects of caffeine and dbcAMP on olive baboon (Papio anubis) sperm

BACKGROUND

Improvement of baboon sperm capacitation is necessary for achieving high in vitro fertilization (IVF) rates in baboons. In this study, we evaluated separate and combined effects of caffeine and dbcAMP on baboon sperm capacitation.

METHODS

Sixteen male baboons (n = 16) were electroejaculated. Each sperm sample was divided into two aliquots: one for chemical activation and the other untreated control. Group 1: dbcAMP (n = 6); Group 2: caffeine (n = 6) and Group 3: combination of caffeine and dbcAMP (n = 4). In each aliquot, sperm motility after 30 minutes of incubation was evaluated as well as zona pellucida (ZP) binding ability after overnight incubation with 4-5 ZP from unfertilized human oocytes.

RESULTS

Sperm motility and ZP binding ability in all chemically activated groups increased significantly as compared to their respective controls (P < 0.05).

CONCLUSION

Combined and separate effects of caffeine and dbcAMP increases baboon sperm motility and ZP binding ability and may improve baboon IVF.

Comparison of outcomes of conventional intracytoplasmic sperm injection and intracytoplasmic sperm injection using sperm bound to the zona pellucida of immature oocytes

This study was to compare the outcomes of conventional (scientist-selected sperm) intracytoplasmic sperm injection (ICSI) and a modified ICSI using zona pellucida (ZP)-bound sperm. Although with 39 couples in each group there was no statistical significance in fertilization, embryo development, implantation, and fetal heart clinical pregnancy rates, the higher implantation and clinical pregnancy rates with ZP-bound sperm encourages further evaluation with larger numbers of subjects using sibling oocytes to determine if the ZP-bound sperm are biologically and functionally superior.

Release of DEFB126 from macaque sperm and completion of capacitation are triggered by conditions that simulate periovulatory oviductal fluid

Capacitation of macaque sperm in vitro has been achieved efficiently only with the addition of both cyclic nucleotides and methylxanthines. The use of these exogenous sperm activators clouds an understanding of the normal mechanisms underlying capacitation and may slow early embryo development following in vitro fertilization (IVF). We demonstrate that culture medium which simulates periovulatory oviductal fluid with respect to bicarbonate (HCO(3)(-)) and glucose concentration induces capacitation in a high percentage of macaque sperm as determined by the ability of sperm to undergo both the release of coating protein DEFB126 and the zona pellucida-induced acrosome reaction (AR). Few sperm were able to undergo the AR following 6 hr incubation in medium containing either 35 mM HCO(3)(-) (approximately 7.2 pH) or 90 mM HCO(3)(-) (approximately pH 7.8) with 5 mM glucose. When glucose concentration was lowered to 0.5 mM to match levels reported for women at midcycle, the AR rate increased significantly in sperm incubated in both levels of HCO(3)(-), indicating that glucose interferes with sperm responsiveness to increasing HCO(3)(-) concentration observed in the primate oviduct during ovulation. Even greater synchronization of capacitation could be achieved with nonphysiologic extremes of alkalinity or energy substrate deprivation. In the latter case, sperm achieved high rates of IVF. A shift in pH from 7.2 to 7.8 in a HEPES-buffered medium was sufficient to remove DEFB126 from the surface of most sperm after only 3 hr. The loss of DEFB126 from sperm under periovulaory fluid conditions has implications for the timing of release of sperm from the oviductal reservoir.

Relationship between seminal plasma zinc concentration and spermatozoa-zona pellucida binding and the ZP-induced acrosome reaction in subfertile men

The aim of this study was to determine the relationship between seminal zinc concentration and spermatozoa-zona pellucida (ZP) binding and the ZP-induced acrosome reaction (ZPIAR) in subfertile men. Semen analyses and seminal zinc concentration assessments were carried out according to the World Health Organization manual for 458 subfertile men. A spermatozoa-ZP interaction test was carried out by incubating 2 x 10(6) motile spermatozoa with a group of four unfertilized oocytes obtained from a clinical in vitro fertilization programme. After 2 h of incubation, the number of spermatozoa bound per ZP and the ZPIAR of ZP-bound spermatozoa were examined. The effect of adding 0.5 mmol L(-1) zinc to the media on the ZPIAR of spermatozoa from normozoospermic men was also tested in vitro. Seminal zinc concentration positively correlated with sperm count and duration of abstinence, but negatively correlated with semen volume. On analysis of data from all participants, both spermatozoa-ZP binding and the ZPIAR were significantly correlated with sperm motility and normal morphology, but not with seminal zinc concentration. However, in men with normozoospermic semen, the seminal zinc concentration was significantly higher in men with defective ZPIAR (< 16%) than in those with normal ZPIAR (>or= 16%) (P < 0.01). The addition of 0.5 mmol L(-1) zinc to the culture media had no effect on spermatozoa-ZP binding, but significantly reduced the ZPIAR in vitro (P < 0.001). In conclusion, seminal zinc concentration is correlated with sperm count and the duration of abstinence in subfertile men. In men with normozoospermic semen, high seminal zinc concentration may have an adverse effect on the ZPIAR.

Influence of Campylobacter fetus subsp. fetus on ram sperm cell quality

Campylobacter fetus subsp. fetus infection can occur in female sheep, causing infertility or abortion. Despite extensive research on the effect of these bacteria on female fertility, little research has been done on the influence of C. fetus subsp. fetus on the male factor. Our objective was to examine the influence of C. fetus subsp. fetus on ram sperm. Motility index, percentage of live spermatozoa, mean αt value (an indication of the chromatin stability of the sperm cell) and percentage of sperm cells expressing the FAS receptor were measured in sperm incubated in the presence or absence of C. fetus subsp. fetus. The motility index and viability of sperm incubated with the bacteria were lower than those of untreated sperm samples after 5 h. In bacteria-incubated sperm cells, the percentage expressing FAS receptor was already significantly elevated at 15 min. Bacteria-incubated sperm showed a greater prevalence of morphological damage. The bacteria were attached to tail and acrosome regions, and the sperm damage was concentrated in both the motility and chromatin regions. Bacteria-infected sperm cells showed a decrease in motility, increase in early acrosome reaction and chromatin damage. Similar effects were induced by incubation of the sperm with supernatants from C. fetus subsp. fetus cultures. Thus this study demonstrates that C. fetus subsp. fetus has a detrimental effect on the quality of ram sperm.

Enhancement of sperm-zona pellucida (ZP) binding capacity by activation of protein kinase A and C pathways in certain infertile men with defective sperm-ZP binding

BACKGROUND

Defective sperm-zona pellucida (ZP) binding (DSZPB) is a common cause of failure of fertilization in vitro. This study was to determine if DSZPB is caused by defective pathways upstream of protein kinase A (PKA) and C (PKC), or reduced protein tyrosine phosphorylation (TP).

METHODS

Infertile men with DSZPB and either normal sperm morphology (NSM) > or = 14% (n = 15) or < or =5% (n = 15) were studied. Sperm-ZP binding test was performed by incubation of motile sperm with oocytes for 2 h with or without dibutyryl cyclic AMP (dbcAMP, PKA activator) or phorbol myristate acetate (PMA, PKC activator). TP of capacitated sperm in medium was assessed by immunofluorescence with an anti-phosphotyrosine monoclonal antibody.

RESULTS

For normal sperm with normal sperm-ZP binding, both PMA and dbcAMP significantly enhanced sperm-ZP binding in a dose-response manner. Only dbcAMP, but not PMA, significantly increased TP of capacitated sperm. In DSZPB men with severe teratozoospermia (NSM < or = 5%), neither PMA nor dbcAMP enhanced sperm-ZP binding, despite dbcAMP significantly increasing the TP of capacitated sperm for all samples. In contrast, for DSZPB with NSM > or = 14%, PMA caused significantly increased sperm binding up to normal levels (> or =40 sperm bound/ZP) in five men, and dbcAMP had a similar result in two men. Again TP was significantly enhanced only by dbcAMP, but not by PMA.

CONCLUSIONS

There is defective signalling in pathways upstream of PKC and PKA in some men with DSZPB and normal semen analysis. Stimulation of TP by dbcAMP does not enhance sperm-ZP binding capacity in DSZPB men with low TP, regardless of sperm morphology.

The association between polypronucleate zygote formation with certain motion characteristics of sperm and IVF outcome

PURPOSE

To determine the efficiency of sperm motion characteristics as predictors for normal (2PN) and polypronulceate (PPN) zygotes in IVF.

METHODS

A retrospective cohort analysis for a total of 230 couples undergoing IVF treatment in a single infertility center.

RESULT(S)

Subsequent to semen analysis and hemizona assay, unexpected fertilization failure would appear to have occurred only extremely rarely (1/236, 0.4%). The rate of PPN, however, did arise and appeared to be related to certain sperm motion characteristics, such as lateral head displacement and concentration of progressive motile sperm. Interestingly, the patients featuring a high PPN rate (>20%) was associated with a greater pregnancy rate than those featuring a low PPN rate (<20%).

CONCLUSION

The sperm motion characteristics examined herein could be utilized to predict the rate of PPN in IVF. In order to enhance the rate of 2PN and maintain the relative high rate of clinical pregnancy, an efficient method needs further investigation and development.

Is sperm evaluation useful in predicting human fertility?

Traditionally, the diagnosis of male infertility has relied upon microscopic assessment and biochemical assays to determine human semen quality. The conventional parameters given most importance have been the concentration, motility, and morphology of sperm in the ejaculate. Most laboratories also include ‘sperm suitability’ tests where the subpopulations of sperm more likely to finish the marathon journey to the oocyte are separated by density centrifugation. These tests are essential to provide the fundamental information on which clinicians base their initial diagnosis. However, none of these parameters addresses sperm function and their clinical value in predicting fertility is questionable. The advent of intracytoplasmic sperm injection (ICSI) has further reduced the significance and perceived need for sperm quality tests since ICSI requires only one sperm, not subject to classic, or indeed any, tests for the procedure to be successful. Over the past decade, a number of laboratory tests have been developed to determine properties of sperm function. These include quantitative sperm motion parameters, capacitation, basal and induced acrosome reactions, sperm–zona pellucida interactions and nuclear and mitochondrial sperm DNA but few have been adopted into routine clinical use. International collaborations should be initiated to develop clinically relevant molecular and functional tests with agreed protocols and clinical thresholds as a matter of urgency.

Secretory mechanisms and Ca2+ signaling in gametes: similarities to regulated neuroendocrine secretion in somatic cells and involvement in emerging pathologies

Recent studies demonstrate that regulated secretion in probably all mammalian cells, from gonadotropes to gametes, utilizes similar signaling systems, intracellular Ca(2+) regulation, Ca(2+)-dependent proteins, cytoskeletal participation, and SNARE-mediated fusion. Thus, highly specialized cells, like sperm and eggs, should no longer be considered to have evolved a cell-type specific secretory mechanism. In gametes, Ca(2+)-dependent proteins and enzymes transduce elevations of intracellular Ca(2+) into secretory events, i.e., exocytosis of the acrosome in sperm and cortical granules in the egg. Just as secretory deficiencies have clinical consequences in endocrine and exocrine cells, failure of secretion of cortical granules or the acrosome can result in failure of normal fertilization or fertilization followed by abnormal development. With the advent of human in vitro fertilization, such gamete pathologies have been recently identified and have led to new clinical procedures to achieve normal fertilization and pregnancies. A better understanding of the common Ca(2+)-dependent secretory pathways in both gametes and somatic cells should be beneficial to investigating mis-regulation in either cell type.

Evaluation of reproductive potential after intracytoplasmic sperm injection of varied human semen tested by antiacrosomal antibodies

OBJECTIVE

To determine whether varied human spermatozoa, as detected with monoclonal antibodies against acrosomal proteins, have an influence on fertilization, transfer, pregnancy, and implantation rates when intracytoplasmic sperm injection is used.

DESIGN

A retrospective study.

SETTING

A private IVF center and academic research laboratory.

PATIENT(S)

One thousand two hundred forty men participating in the intracytoplasmic sperm injection program.

INTERVENTION(S)

Sperm were divided into seven groups: oligozoospermia, oligoasthenozoospermia, and oligoasthenoteratozoospermia and fresh and frozen-thawed epididymal and fresh and frozen-thawed testicular sperm. Fertilization, transfer, pregnancy, and implantation rates were recorded in each category. Sperm were tested with antibodies for detection of the of the sperm acrosome.

MAIN OUTCOME MEASURE(S)

Fertilization, transfer, pregnancy and implantation rates, and percentage of acrosome-reacted cells.

RESULT(S)

The fertilization rate and statistical evaluation showed differences between morphologically normal and pathological sperm and other groups. The freezing-thawing procedure had no influence on the fertilization of testicular sperm, but epididymal frozen-thawed sperm had a higher fertilization rate. Immunofluorescence proved decreasing sperm quality in all groups compared with the control group. This difference is not manifested in other parameters (transfer, pregnancy, implantation rates).

CONCLUSION(S)

The spermatozoa with varied semen characteristics and good quality, also detected with specific antibodies, gave the best fertilization rates. The paternal effect is not proved in other parameters.

Pneumonitis and Eosinophilia After In Vitro Fertilization Treatment

A 33-year-old woman presented to the emergency department (ED) with tachypnea, tachycardia, and hypoxia, complaining of dyspnea and paroxysms of dry cough for 2 days. The patient had undergone an unsuccessful in vitro fertilization procedure 1 month earlier and had had another embryo implantation 6 days earlier. She had been receiving intramuscular injections of estradiol and progesterone in sesame oil to support implantation. A chest radiograph demonstrated extensive bilateral pulmonary consolidation; a leukocytosis count of 19.7 x 10(9) with 20% eosinophils was noted on a CBC count. A MEDLINE search yielded a case report in infertility literature describing an eosinophilic pneumonitis with similar clinical features after injections of progesterone in sesame oil. Treatment with intravenous corticosteroids was initiated in the ED, resulting in symptom and chest radiograph result improvement within 2 days and sparing the patient further imaging and antibiotic therapy.

Biological Effects of Recombinant Human Zona Pellucida Proteins on Sperm Function1

The initial interaction between gametes takes place at the level of the sperm surface and the zona pellucida (ZP), the extracellular matrix of the egg in mammals. Successful fertilization requires the proper molecular recognition of the ZP by the sperm. Recently, human ZP was demonstrated to be composed of four proteins: ZP1, ZP2, ZP3, and ZP4. The goals of this study were to determine the effects of recombinant human ZP2, ZP3, and ZP4 on human sperm acrosomal exocytosis and sperm motility. Exposure of sperm to ZP proteins, alone or in combination, promoted acrosomal exocytosis in a time-dependent manner. This effect occurred in parallel with a considerable decrease in progressive motility, coincident with an increase in nonprogressive sperm motility. An analysis of kinetic parameters of ZP-treated sperm demonstrated that a characteristic motility pattern could be defined by values of curvilinear velocity > 63.9 mum/s and linearity <or= 15.5%. A strong correlation between curvilinear velocity and the amplitude of lateral head displacement was also observed. The incidence of sperm having these particular kinetic parameters increased after exposure to ZP proteins. These studies of two processes involved in sperm penetration through the ZP confirm that zona glycoproteins promote acrosomal exocytosis and now establish an additional role for these components as modifiers of sperm motility.

Tyrosine phosphorylation on capacitated human sperm tail detected by immunofluorescence correlates strongly with sperm-zona pellucida (ZP) binding but not with the ZP-induced acrosome reaction

BACKGROUND

Protein tyrosine phosphorylation (TP) of human sperm is related to sperm capacitation and zona pellucida (ZP) binding. The aim of this study was to determine whether the TP of capacitated sperm is a useful marker for the ability of sperm to bind to the ZP and undergo the ZP-induced acrosome reaction (AR).

METHODS

Semen samples were obtained from 115 subfertile men with sperm count > or =20 x 10(6)/ml, motility > or =25% and variable morphology. Motile sperm (2 x 10(6)/ml) selected by swim-up were incubated with four oocytes for 2 h, and the number of sperm bound to the ZP and the ZP-induced AR was examined. TP of sperm tail was assessed by immunofluorescence (IF) with anti-phosphotyrosine monoclonal antibody. The time course and effects of dibutyryl cyclic adenosine monophosphate (dbcAMP) and phorbol myristate acetate (PMA) on TP were also studied.

RESULTS

TP was stimulated more by dbcAMP (P < 0.001) and less by PMA (P < 0.05). TP increased significantly with time of incubation of sperm. TP was not detectable on the surface of unfixed live sperm by either Dynabeads or IF. Sperm TP at 2, 4 and 20 h incubation was all significantly correlated with sperm-ZP binding but not with the ZP-induced AR.

CONCLUSION

Sperm TP detected by IF correlates strongly with sperm-ZP binding capacity but not with the ZP-induced AR. This simple IF assay of TP may be a clinically useful test of sperm function that is predictive of normal sperm ZP-binding capacity.

World Health Organization grade 'a' motility and zona-binding test accurately predict IVF outcome for mild male factor and unexplained infertilities

BACKGROUND

The aim of this study was to determine the pronostic value of a sperm-zona pellucida (ZP) binding assay, combined with World Health Organization (WHO) grade 'a' sperm motility on the day of the IVF attempt, to predict sperm fertilizing ability in unexplained and moderate male factor infertilities.

METHODS

In total, 84 couples (64 unexplained infertility; 20 male factor) underwent both a sperm-ZP binding assay and an IVF attempt, irrespective of the test's result. The test was negative when grade 'a' motility was #5% and/or the ZP binding index was <0.7. Fertilization and pregnancy rates were related to the test's results.

RESULTS

Thirty-one patients had a negative test (group N) and 53 a positive test (group P). A difference was observed concerning the fertilization rate [median (range): 0 (0-75%) versus 50 (0-100%); P = 0.0001] and the number of cycles with fertilization rate <20% (65 versus 23%; P = 0.0002) between groups N and P respectively. In the group of unexplained and male factor infertilities, the test showed a sensitivity of 83 and 60%, specificity of 50 and 90%, positive predictive value of 76 and 86%, and negative predictive value of 61 and 69% respectively.

CONCLUSION

Sperm-ZP binding test, combined with WHO grade 'a' motility assessment, is relevant to prevent IVF fertilization failures in unexplained infertility and, most particularly, in moderate male factor infertility.