Relevance of acrosome function in the evaluation of semen in vitro fertilizing ability

Tissue and sperm handling before assisted reproductive technology (ART): A systematic review

Objective

: To explore the medical literature on techniques of tissue and sperm handling after surgical retrieval for intracytoplasmic sperm injection (ICSI).

Methods

: A search was performed in PubMed and Google Scholar databases, according to a modified Preferred Reporting Items for Systemic Reviews and Meta-Analyses (PRISMA) guideline, considering the studies investigating tissue handling and sperm selection techniques for ICSI.

Results

: Overall, 42 articles were included in this study, investigating sample handling, methods for sperm selection, and the use of chemical compounds to improve sperm motility and fertilisation rates.

Conclusion

: The ideal sperm handling method should provide a high sperm count, high vitality and appropriate sperm function, without side-effects. In this review the most common and useful techniques are described and the best combination strategies discussed in clinical scenarios.

Human sperm acrosome function assays are predictive of fertilization rate in vitro: a retrospective cohort study and meta-analysis

OBJECTIVE

To determine whether acrosome function scoring-including acrosomal enzyme (AE) levels and acrosome reaction (AR) results-can predict fertilization rate in vitro.

METHODS

We examined the predictive value of acrosomal enzymes (AE) determined by spectrophotometry/N-α-benzoyl-DL-arginine-p-nitroanilide for fertilization rate (FR) in vitro in a retrospective cohort study of 737 infertile couples undergoing IVF therapy. Additionally, a meta-analysis was done for prospective cohort or case-control studies; the following summary measures were reported to expand upon the findings: pooled spearman correlation coefficient (Rs), standardized mean difference (SMD), sensitivity (SEN), specificity (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic score (DS), diagnostic odds ratio (DOR), and area under the summary receiver operating characteristic curve (AUC).

RESULTS

Lower AE levels determined by spectrophotometry with a cut-off value of <25μIU/10⁶ spermatozoa were predictive of total fertilization failure (TFF) with moderate SEN (88.23%) and low SPE (16.50%). On meta-analysis, a total of 44 unique articles were selected, but given the multiple techniques described there was a total of 67 total datasets extracted from these 44 articles, comprising 5356 infertile couples undergoing IVF therapy. The AE levels or induced AR% was positively correlated with FR (Rs = 0.38, SMD = 0.79; Rs = 0.40, SMD = 0.86, respectively). Lower AE levels or induced AR% was predictive of lower fertilization rate with moderate accuracy (AUC = 0.78, AUC = 0.84, respectively); this was accompanied by low SEN/moderate SPE (0.57/0.85), moderate SEN/moderate SPE (0.79/0.87), respectively. For AE assay, the diagnostic performance in Asia (Rs = 0.24, SMD = 0.50) was inferior to that in North America (Rs = 0.54, SMD = 0.81) and Europe (Rs = 0.46, SMD = 0.92). Cryopreserved spermatozoa (SMD = 0.20, P = 0.204) were inferior to fresh spermatozoa (SMD = 0.89, P <  0.001). Sperm preparation yielded inferior results as compared to no preparation; spermatozoa after swim up were weak relevant (Rs = 0.27, P = 0.044); and there was no correlation for spermatozoa after a discontinuous gradient (SMD = 1.07, P >  0.05). Lower AE levels determined by fluorometry or substrate assay were used for predicting lower FR with low sensitivity and high specificity; the spectrophotometry assay had an uncertain predictive value. For induced AR assay, the diagnostic performance in the other areas was inferior to that in Africa (Rs = 0.65, SMD = 1.86). No preparation or double preparation yielded inferior results as compared to one preparation (Rs = 0.41); discontinuous gradient (Rs = 0.17, SMD = 0.47) was inferior to swim up (Rs =0.65, SMD = 1.51). Nonphysiological triggers (SMD = 0.81) did not differ from physiological triggers (SMD = 0.95) in general; ZP (Rs = 0.63) or mannose (Rs = 0.59) was superior to other physiological or nonphysiological triggers; and there was no correlation for human follicle fluid, progesterone, cyclic adenosine 3'-5'-phosphate analogue and phorbol ester-BSA-GlcNAc Neoglycoproteins with N-acetylglucosamine residues. Lower induced AR% determined by indirect immunofluorescence, direct immunofluorescence with lection, or triple stain was used for predicting lower FR, with moderate sensitivity/high specificity, moderate sensitivity/high specificity, or high sensitivity/low specificity.

CONCLUSIONS

Although the correlation between acrosome function scoring and FR was significant, the assays were neither highly sensitive nor specific. Additionally, the diagnostic performance showed regional effects as well as an effect of the sperm preparation or assay method. More studies of multicenter, large-scale, careful design and synthesizing multiple sperm functional assays and oocyte quality assays are still needed in clinical settings to better predict fertilization outcome in IVF.

Predictive value of selected sperm parameters for classical in vitro fertilization procedure of oocyte fertilization

A proportion of fertilized oocytes during classical in vitro fertilization (IVF) procedure was analysed depending on the following factors: number of mature oocytes, seminological criteria such as sperm morphology in raw semen and after its selection in a density gradient (six structural defects of a male gamete were taken into consideration), sperm concentration, motility parameters according to World Health Organization criteria and the functional tests: hypo-osmotic swelling assay and acrosomal reaction induced by calcium ionophore. Evaluation of DNA content in sperm by image cytometry and determination of malonyldialdehydes in seminal plasma were also performed. Seventy-nine semen samples from patients undergoing IVF were assessed. Apart from significant correlations obtained for selected semen parameters and proportion of fertilized eggs, logistic regression analysis showed that the best predictive factors for oocyte fertilization were normal morphology of sperm before and after gradient selection, grade B and C of sperm movement in raw semen, and DNA content after density gradient centrifugation, which all accounted for 76.7% of fertilization predictive value.

Sperm function and assisted reproduction technology

The evaluation of different functional sperm parameters has become a tool in andrological diagnosis. These assays determine the sperm's capability to fertilize an oocyte. It also appears that sperm functions and semen parameters are interrelated and interdependent. Therefore, the question arose whether a given laboratory test or a battery of tests can predict the outcome in in vitro fertilization (IVF). One-hundred and sixty-one patients who underwent an IVF treatment were selected from a database of 4178 patients who had been examined for male infertility 3 months before or after IVF. Sperm concentration, motility, acrosin activity, acrosome reaction, sperm morphology, maternal age, number of transferred embryos, embryo score, fertilization rate and pregnancy rate were determined. In addition, logistic regression models to describe fertilization rate and pregnancy were developed. All the parameters in the models were dichotomized and intra- and interindividual variability of the parameters were assessed. Although the sperm parameters showed good correlations with IVF when correlated separately, the only essential parameter in the multivariate model was morphology. The enormous intra- and interindividual variability of the values was striking. In conclusion, our data indicate that the andrological status at the end of the respective treatment does not necessarily represent the status at the time of IVF. Despite a relatively low correlation coefficient in the logistic regression model, it appears that among the parameters tested, the most reliable parameter to predict fertilization is normal sperm morphology. (Reprod Med Biol 2005; 4: 7-30).

Acrosome reaction in fertile and subfertile boar sperm

The main purpose of sperm evaluation is to predict its fertilizing ability. However, basic sperm test results show a low correlation with fertilizing ability. The purpose of this study was to determine whether there is an association between acrosome reaction (AR) and the incidence of subfertility of normal sperm boar. The production records of 22 farms were analyzed to identify boars with low fertility and/or prolificity, classified as subfertile. Twenty-two subfertile boar semen samples were analyzed and compared with 51 samples of fertile boars. Sperm were capacitated during 4 h at 39 degrees C. viability was determined by bisbenzimide (Hoechst-33258) staining. Acrosome reaction was assessed with fluorescein isothiocyanate conjugated Pisum sativum agglutinin. The percentage of spontaneous acrosome reaction (SAR) was not significantly different in fertile (4.5%) and subfertile boars (4.75%) (p > .05). Nevertheless, the percentage of progesterone-induced acrosome reaction (IAR) was significantly lower in subfertile boars (5.75%) as compared with fertile boars (10%) (p < .01). These results suggest that assessment of IAR in vitro may be a useful parameter to identify subfertility in boars.

The postwash total progressively motile sperm cell count is a reliable predictor of total fertilization failure during in vitro fertilization treatment

OBJECTIVE

To predict the chance of total fertilization failure (TFF) before the day of ovum pickup with known semen and female variables.

DESIGN

A statistical model was constructed to predict TFF by retrospective analysis (2,366 couples) and subsequently tested on a new IVF population (917 couples).

SETTING

Academic tertiary referral center.

PATIENT(S)

Three thousand three hundred eighty-three couples who underwent an IVF-ET treatment.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The ability to predict the probability of TFF in IVF.

RESULT(S)

Two variables-postwash total progressively motile sperm cell count (postwash TPMC) and number of follicles-were found to be significant. Taking a probability of 25% as an acceptable risk of TFF, we calculated that a postwash TPMC of <1.1 x 10(6) cells results in a risk of TFF of >25%. Low responders (<4 follicles) needed a postwash TPMC of >2.2 x 10(6) cells to reduce the risk of TFF to <25%. High responders (>15 follicles) needed only 0.35 x 10(6) postwash progressively motile spermatozoa.

CONCLUSION(S)

When postwash TPMC and number of follicles are known and an unacceptable TFF outcome is expected, one can propose an ICSI procedure a few days before the day of ovum pickup.

Acrosome reaction: methods for detection and clinical significance

The present article reviews the methods for detection and the clinical significance of the acrosome reaction. The best method for the detection of the acrosome reaction is electron microscopy, but it is expensive and labour-intensive and therefore cannot be used routinely. The most widely used methods utilize optical microscopy where spermatozoa are stained for the visualization of their acrosomal status. Different dyes are used for this purpose as well as lectins and antibodies labelled with fluorescence. The acrosome reaction following ionophore challenge (ARIC) can separate spermatozoa that undergo spontaneous acrosome reaction from those that are induced, making the result of the inducible acrosome reaction more meaningful. Many different stimuli have been used for the induction of the acrosome reaction with different results. The ARIC test can provide information on the fertilizing capability of a sample. The ARIC test was also used to evaluate patients undergoing in vitro fertilization since a low percentage of induced acrosome reaction was found to be associated with lower rates of fertilization. The cut-off value that could be used to identify infertile patients is under debate. Therapeutic decisions can also be made on the basis of the value of the ARIC test.

Computer-assisted assessment of sperm morphology: comparison with conventional techniques

The aim of the present study was to compare conventional and computer-assisted morphology assessment of spermatozoa. Sixty-two semen samples from patients undergoing in vitro fertilization (IVF) and 40 samples from patients undergoing an intracytoplasmic sperm injection (ICSI) were studied using both techniques. The percentage of normal spermatozoa found was closely correlated between the techniques (r=0.788, p < 0.0001). The intra-operator variation was low for both techniques but the inter-operator variation was much higher with the conventional than with the computer-assisted method (coefficient of variation = 0.43 vs. 0.08, respectively, for conventional and computer-assisted assessments). The percentage of spermatozoa with normal morphology, as well as sperm motility, was significantly enhanced after PureSperm preparation, whatever the method used for assessment. In the IVF study, fertilization rate was poorly correlated with sperm morphology using both methods. However, combined with motility, morphology assessed with the computer allowed discrimination of two groups of patients with significantly different fertilization rates (30.5 +/- 5.4% vs. 63.1 +/- 5.4%, p < 0.0001). In contrast, the fertilization rate in ICSI was influenced neither by sperm morphology nor by motility. In conclusion, computer-assisted assessment of sperm morphology has a slightly better predictive value for ART than conventional assessment, but above all is much more reproducible, allowing standardization.

Flow cytometric analysis of semen preparation, and assessment of acrosome reaction, reactive oxygen species production and leucocyte contamination in subfertile men

Reactive oxygen species (ROS) production, poor acrosome reaction ability, and leucocyte and round cell contamination of semen are associated with diminished male fertility. In addition to the assessment of these variables, the number of abnormal and round cells in semen preparation was studied by flow cytometry. Men with varying degree of fertility despite normal concentrations and motility of spermatozoa were investigated. Group 1 consisted of semen donor candidates (n = 25), group 2 of patients with acceptable fertilization in vitro, but diminished fertility in vivo (n = 56), and group 3 of patients with poor (< 25%) fertilization in vitro (n = 32). The subfertile men in groups 2 and 3 had lower concentrations and poorer rapid progressive motility of spermatozoa than the men in group 1. Using flow cytometry, the number of events in the round cell gate in the Percoll-prepared semen sample was higher in the subfertile men than in the donors, independently of the differences in other semen parameters. However, there were no significant differences between the groups in the number of round cells in native semen by microscopic analysis, or in ROS production or acrosome reaction. In conclusion, flow cytometric assessment of round cells may be a useful method in the investigation of male fertility.

Relationship between creatine kinase levels and clinical diagnosis of infertility

PURPOSE

The creatine kinase level indicates sperm maturity and correlates with the spermatozoal fertilizing potential. The relationship between creatine kinase levels in subfertile men and their clinical diagnosis was examined.

METHODS

Patients with unexplained infertility (n = 34), varicocele (n = 20), postvasectomy reversal (n = 7), or cancer (n = 22) were included in this prospective clinical study. The control group consisted of healthy normal donors (n = 15).

RESULTS

The median and interquartile range values of creatine kinase for each group were as follows: normal donors, 0.061 U/10(8) sperm (0.056 to 0.076 U/10(8) sperm); idiopathic male factor, 0.119 U/10(8) sperm (0.061 to 0.190 U/10(8) sperm); varicocele, 0.392 U/10(8) sperm (0.209 to 1.494 U/10(8) sperm); postvasectomy reversal, 0.589 U/10(8) sperm (0.425 to 4.043 U/10(8) sperm); and cancer, 0.068 U/10(8) sperm (0.047 to 0.168 U/10(8) sperm). Sperm creatine kinase levels were significantly higher in patients with varicocele compared to normal donors (P = 0.0001), cancer patients (P = 0.0002), and men with idiopathic infertility (P = 0.0009). Sperm concentration and creatine kinase level were inversely correlated in patients (r = -0.7, P < 0.001) but not in normal donors.

CONCLUSIONS

Semen quality is poorer in subfertile patients with clinical varicocele and postvasectomy reversal than in cancer patients and patients with idiopathic male infertility. That the creatine kinase levels in cancer patients were similar to those of normal donors suggests that the final phase of spermatogenesis may not be altered in men with cancer; thus semen from these patients should be banked to ensure fertility after cancer treatment.

Accuracy of computer-assisted semen analysis in prefreeze and post-thaw specimens with high and low sperm counts and motility

OBJECTIVES

We evaluated the accuracy and precision of computer-assisted semen analysis (CASAs) to determine whether variations in the CASA results were related to the type of analyzer or to the type of specimens analyzed.

METHODS

Semen specimens were analyzed manually and by CASA before freezing and after thawing. Multiple ejaculates (220 semen specimens) from normal healthy donors (n = 8) and 131 semen specimens from 57 patients with cancer were assessed.

RESULTS

The differences between CASA and manual sperm counts and percent motility were higher in prefreeze and post-thaw specimens at sperm concentrations of less than 20 x 10(6)/mL. The differences between CASA and manual results were significant for cancer patients, compared with normal donors (P <0.01).

CONCLUSIONS

CASA results are unreliable at sperm counts of less than 20 x 10(6)/mL and post-thaw motility is generally underestimated by CASAs.

Spontaneous and follicular fluid-induced acrosome reaction in sperm samples from in vitro fertilizing and nonfertilizing normozoospermic patients

PURPOSE

One of the most challenging and intriguing groups of infertile patients is that of normozoospermic men who have repeatedly not achieved fertilization in vitro. These cases probably present a wide range of gamete disorders manifested at different stages of the fertilization process. The occurrence of spontaneous and follicular fluid (FF)-induced acrosome reactions (ARs) in in vitro fertilizing and nonfertilizing specimens from normozoospermic IVF patients was assessed, and the effect of Percoll and cryopreservation on the incidence of ARs was evaluated.

METHODS

Semen samples from 62 normozoospermic (15 in vitro nonfertilizing and 47 fertilizing) patients were analyzed. Spermatozoa were double-stained with FITC-conjugated Pissum sativum lectin, to assess their acrosomal status, and propidium iodide, to evaluate their vitality, using flow cytometry analysis.

RESULTS

A lower average of AR incidence was observed in the nonfertilizing than in the fertilizing group with all treatments. Both groups exhibited an increase in the proportion of ARs following incubation with FF. This rise was most prominent when Percoll-separated fractions were used (15.8 and 25.6% AR in the nonfertilizing and fertilizing groups, respectively). Thawed cryopreserved and fresh fertilizing samples exhibited similar AR rates.

CONCLUSIONS

That normozoospermic recurrently nonfertilizing compared to fertilizing semen samples have a lower capacity to undergo ARs is suggested.

Creatine kinase level and lipid peroxidation rate in human spermatozoa from patients with cancer

PURPOSE

The present study assessed whether the poor semen quality in patients with cancer results from the inhibition of sperm maturation as indicated by creatine kinase or from increased oxidative stress as assessed by lipid peroxidation of the sperm membrane.

METHODS

Cryopreserved semen specimens from patients with testicular (n = 10) and nontesticular (n = 12) cancer and normal healthy donors (n = 14) were analyzed for lipid peroxidation and creatine kinase levels.

RESULTS

The levels of creatine kinase and malonaldehyde did not differ among testicular or nontesticular patients with cancer or normal healthy donors.

CONCLUSIONS

Poor semen quality in testicular and nontesticular patients with cancer is not related to creatine kinase or lipid peroxidation levels; it may be related to other factors.

Acrobeads test as a predictor of fertilization in vitro

PROBLEM

To determine whether the results of the Acrobeads test, which measures the expression of the complement regulator molecule CD46 on the inner acrosomal membrane following the acrosome reaction, accurately identifies semen specimens that will exhibit reduced or failed fertilization following conventional IVF insemination.

METHOD

The Acrobeads test was performed on semen specimens from 97 consecutive patients preparing to undergo an IVF cycle utilizing a standardized insemination protocol. Motile sperm populations were examined at 6 h and 24 h post-isolation for sperm-bead agglutination. Results of the Acrobeads test were compared to that of TRITC-PSA staining in matched specimens to directly measure the spontaneous loss of acrosome content. The percentages of TRITC-PSA-negative sperm were determined in freshly isolated motile populations and in duplicate aliquots incubated 18 to 20 h under sperm capacitating conditions. The relationship between the results of both analyses estimating spontaneous acrosome reactions and the rate of fertilization of metaphase II oocytes was examined.

RESULTS

The Acrobeads score did not correlate significantly with the rate of fertilization by insemination at 6 h or at 24 h. The negative predictive value of this test was 21.4%. There was no correlation between the Acrobeads score and the percentage of sperm undergoing a spontaneous acrosome reaction as detected by TRITC-PSA labeling. In contrast, the increment increase in the percentage of spontaneous acrosome reactions as quantified by TRITC-PSA staining was correlated with the fertilization rate.

CONCLUSIONS

Contrary to previous reports, our prospective, double-blinded study failed to demonstrate that the Acrobeads test can accurately predict fertilization outcome in IVF. Therefore, the routine use of this test to screen patients prior to an IVF cycle in order to select appropriate treatment (i.e., ICSI) cannot be recommended.

Submicroscopic mathematical evaluation of spermatozoa in assisted reproduction. 2. In vitro fertilization. (Notulae seminologicae. 7)

This paper belongs to a series of applications of the Baccetti et al. formula (1) to the submicroscopical mathematical examination of human spermatozoa used for assisted reproduction. The present experiment concerns IVF, a technique requiring careful evaluation of sperm quality to predict the success of the program. Our results demonstrate that the sperm submicroscopic characters introduced in the formula are clearly correlated with the result of IVF. In fact the two numbers concerning sperm quality (percentage of spermatozoa free from structural defects and total number in the ejaculate of spermatozoa free from defects) obtained in successful and unsuccessful IVF groups, showed a large difference. The t distribution in both cases reached a significance of 0.005. The synthetic parameters obtained are therefore a good tool in the prediction of sperm power in in vitro insemination techniques. The most important characteristics seem to be the quality of the acrosomal complex, the status of the chromatin, the shape of mitochondria, the axonemal pattern, and the membrane integrity. All these characteristics are expressed with largely different means in successful and unsuccessful ejaculates (t distribution significant at 0.005). All these data confirm that submicroscopic mathematical diagnosis offers a convincing evaluation of sperm structure and function, involving all organelles, including acrosome function and cell motility. It is also demonstrated that sperm quality is a major factor in the success of IVF and that it is clearly revealed by the integrity of the majority of the sperm organelles.

Validation of a scoring method predicting the in-vitro fertilizing ability of human spermatozoa

The fertilizing ability of human spermatozoa depends upon numerous functions such as motility, normal morphology, ability to bind to the zona pellucida and to undergo the acrosome reaction. Hence a lot of tests have been developed to try and predict IVF results. In a previous study we had established a scoring method, based on parameters such as sperm morphology, vitality, motility and the acrosome reaction, which was able to predict up to 83% of in-vitro fertilization results. The present study aimed to validate this score on a separate set of sperm samples. The results confirmed those of the first series. The score allowed prediction of fertilization failures with a 56% sensitivity, a 91% specificity, a 56% positive predictive value and a 91% negative predictive value. Therefore, this score could be used routinely to choose between conventional IVF and ICSI.