Sperm treatment with pentoxifylline improves the fertilizing ability in patients with acrosome reaction insufficiency

Does in vitro application of pentoxifylline have beneficial effects in assisted male reproduction?

Application of nonspecific phosphodiesterases inhibitors, such as pentoxifylline (PTX), is a strategy utilised to aid sperm selection from immotile sperm samples prior to ICSI. No extensive studies have yet been performed to verify the safety of the clinical outcomes of ICSI after PTX administration. In this article, we summarise the data reported in the literature that assess the implication of in vitro usage of PTX on sperm parameters, as well as clinical outcomes during assisted male reproduction programme.

Supplementation of biotin to sperm preparation medium enhances fertilizing ability of spermatozoa and improves preimplantation embryo development

PURPOSE

Motility of spermatozoa helps not only in planning the type of infertility treatment but also directly reflects the success rate in assisted reproductive technology (ART). Previously, biotin, a water-soluble vitamin, has been shown to increase the motility and longevity of cryopreserved human spermatozoa. The present study was designed to understand the molecular basis of the beneficial effects of presence of biotin in sperm wash medium on early embryo development.

METHODS

The effect biotin supplementation to sperm wash medium on the sperm parameters were assessed in swim-up fraction of normozoospermic and asthenozoospermic ejaculates collected from infertile men. Fertilization and early embryo development was studied using Swiss albino mice.

RESULTS

Even though both biotin and pentoxifylline (PTX) enhanced the motility of spermatozoa from normozoospermic and asthenozoospermic samples, biotin group exhibited higher in vitro survival. Using mouse model, we observed that presence of biotin or PTX in sperm wash medium improved the fertilization rate and blastocyst rate compared to control. Blastocysts from these groups had significantly higher total cell number (P < 0.01) and lower apoptotic index. In silico target prediction revealed that GTPase HRas (HRas), tyrosine-protein phosphatase nonreceptor type 1 (PTP1B), and glucokinase are the probable targets for biotin. Solution-state Nuclear Magnetic Resonance (NMR) studies confirmed that biotin interacts both with human HRas and PTP1B.

CONCLUSION

Our results indicate that presence of biotin in sperm wash medium can improve the fertilization potential and preimplantation embryo development and can be considered as a safe alternate to PTX.

The diagnostic significance of the induced acrosome reaction

In trying to discern potential causes of male infertility, little investigation has been done to determine if there is predictive value in assessing acrosome reaction inducibility of human spermatozoa for clinical interpretation and application. The purpose of this review is to outline what is currently known in terms of the diagnostic significance of the induced acrosome reaction and to discuss what might be anticipated for the future. In constructing this review, every effort has been made to provide a comprehensive literature review for the reader and a number of review articles have been cited to serve as sources for additional related material. Regarding the aforementioned, it is essential to qualify that, with the exception of the Section entitled: ‘General characteristics of capacitation and the acrosome reaction’, only characteristics, properties and areas relevant to human spermatozoa will be addressed. Thus, in total, this review will: (1) provide a general description of capacitation and the acrosome reaction; (2) briefly characterize the acrosome and its properties; (3) address the signalling mechanism(s) by which the acrosome reaction occurs; (4) outline various methods for detecting the acrosome reaction; (5) definein vitroculture conditions that facilitate the acrosome reaction; (6) define agents, i.e., biological and chemical, that induce the reaction; (7) discuss the association of the acrosome reaction with fertilization; (8) discuss the clinical implications of the induced acrosome reaction; (9) discuss the relevance of sperm function assays in general; and lastly, (10) discuss future application of acrosome reaction assessment for the clinical diagnosis of male infertility.

Clinical importance of a micro-assay for the evaluation of sperm acrosome reaction using homologous zona pellucida

This study aimed to develop an acrosome reaction assay using microvolumes of solubilized human zonae pellucidae among 35 couples attending an in vitro fertilization programme. The sperm morphology of the men was classified as g-pattern (5-14% normal forms) and/or normal pattern (> 14% normal forms). All the couples had a history of repeated poor or failed in vitro fertilization rates from previous attempts. A zona-induced acrosome reaction test was performed using homologous 0.25 zona pellucida microl-1 incubated with spermatozoa to induce the acrosome reaction. Acrosome reactions were measured with FITC-PSA staining, and expressed as the difference between zona-induced and spontaneous acrosome reaction spermatozoa. The results indicated that microvolumes of solubilized human zona pellucida could successfully be used to determine the acrosome reaction status of spermatozoa. The results were compared with in vitro fertilization rates of metaphase II oocytes, and analysed with the receiver operating characteristics curve. Receiver operating characteristics analyses divided the patients into two groups: i.e. zona-induced acrosome reaction < 15% and > 15%. The sensitivity and specificity for zona-induced acrosome reaction results versus fertilization were 93% and 100%, respectively. The correlation coefficient between zona-induced acrosome reaction and in vitro fertilization was r = 0.94 (P < 0.0001). Zona-induced acrosome reaction data can be used as an indicator for fertilization failure, thus helping clinicians to refine the therapeutic approach for infertile couples prior to the onset of the treatment.

The effect of pure FSH administration in non-obstructive azoospermic men on testicular sperm retrieval

BACKGROUND

In cases of azoospermia due to impaired spermatogenesis, spermatozoa can be retrieved by sperm extraction (TESE) from testicular biopsy.

OBJECTIVE

To evaluate the efficacy of pure follicle-stimulating hormone (pFSH) on sperm recovery, and measure the predictive value of testicular histology.

STUDY DESIGN

In all, 108 patients were studied. These included those with Sertoli cell-only (n=16), focal spermatogenesis (n=36), maturation arrest (n=19) and hypospermatogenesis (n=37) in previous explorative biopsies. All had normal serum FSH, LH and testosterone levels. In 63 cases, 75IU pFSH were administered, either i.m. or s.c., three times a week, for 3 months and the control group (n=45) no treatment was given.

RESULTS

The sperm retrieval rate was 64% (40/63 pts.) in pFSH treated men versus 33% (15/45 pts.) in controls (P<0.01). In Sertoli cell-only patients, the rate was 2/7 (28%) versus 4/9 (44%) in controls and treated men, respectively (P>0.05); and 3/8 (37%) versus 5/11 (45%) in maturation arrest (P>0.05); 6/14 (42%) versus 18/23 (78%) in hypospermatogenesis (P<0.05); and 4/16 (25%) versus 13/20 (65%) in focal spermatogenesis (P<0.01). Treatment with pFSH also improved the quantity of retrieved spermatozoa compared to control values (P<0.05).

CONCLUSION

pFSH treatment improves the success of TESE for non-obstructive azoospermic men with normal FSH levels.

Pentoxifylline improves in vitro fertilization and subsequent development of bovine oocytes

The purpose of this study was to examine whether pentoxifylline improves in vitro fertilization and developmental rates of bovine oocytes. In the first experiment, we examined the effects on the fertilization rate of various concentrations of pentoxifylline (0-7.5 mM) combined with heparin (10 IU/mL). In the second experiment, we examined fertilization cleavage and blastocyst rates after frozen-thawed spermatozoa, obtained from four different bulls, were incubated with heparin (10 IU/mL) with or without caffeine (5 mM) or pentoxifylline (5 mM). In the first experiment, a significantly higher fertilization rate was obtained in heparin containing 5 mM pentoxifylline compared to that in heparin alone or in heparin containing 7.5 mM pentoxifylline (86% vs 60% vs 64%, respectively). The percentage of monospermy in 5 mM pentoxifylline (81%) was significantly higher than in heparin alone (57%). In the second experiment, the interactions among Bulls A, B, C, and D; between treatments (pentoxifylline-with-heparin, caffeine-with-heparin and heparin alone), and between bulls and treatments were analyzed for the number of oocytes penetrated, monospermic oocytes, cleaved oocytes and blastocysts. Among bulls, there was a significant difference in the number of oocytes penetrated (P < 0.01), monospermic oocytes (P < 0.05), cleaved oocytes (P < 0.001), and blastocysts (P < 0.001). Between treatments, there was a significant difference in the number of oocytes penetrated (P < 0.001), monospermic oocytes (P < 0.01) and cleaved oocytes (P < 0.001). Interaction between bulls and treatments was observed for the number of oocytes penetrated (P < 0.05). Individually, for Bulls A, C and D, the numbers of oocytes penetrated and monospermic oocytes in pentoxifylline-with-heparin were significantly higher than in heparin alone. For Bull D, significantly higher results were obtained for the number of oocytes penetrated, monospermic oocytes, cleaved oocytes and blastocysts in pentoxifylline-with-heparin compared to caffeine-with-heparin and heparin alone (P < 0.05). These results suggest that treating sperm with 5 mM pentoxifylline in combination with heparin is effective for bovine in vitro fertilization and it that this treatment is effective even for bulls that produce low fertilization and blastocysts after sperm treatment with caffeine-with-heparin or heparin alone.

Clinical importance of zona pellucida-induced acrosome reaction and its predictive value for IVF

The study aimed to establish zona pellucida induced acrosome reaction response (ZIAR) among 35 couples with normal and G-pattern sperm morphology and repeated poor fertilization results during assisted reproduction treatment. ZIAR tests were performed using 0.25 zona pellucida/microliter co-incubated with spermatozoa for 60 min. Acrosome reactions were measured with FITC-PSA staining, and expressed as the difference between stimulated and unstimulated (spontaneous) sperm populations. Results were compared with IVF rates of metaphase II oocytes. Interactive dot diagrams divided the patients into two groups, i.e. ZIAR <15% and ZIAR > 15%, with mean fertilization rates of 49 and 79% respectively. The sensitivity and specificity for ZIAR results versus fertilization were 93 and 100% respectively. The area under the curve was 99% and the 95% confidence interval did not include 0.5 which implies that the ZIAR test is able to predict fertilization failure among IVF patients. In conclusion, the ZIAR test has diagnostic potential since it can assist the clinician to identify couples that will benefit from intracytoplasmic sperm injection therapy.

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.

Induction of acrosome reaction in human spermatozoa accelerates the time of pronucleus formation of hamster oocytes after intracytoplasmic sperm injection

OBJECTIVE

To assess the relationship between the incidence of acrosome reaction (AR) and the timing of pronucleus (PN) formation after intracytoplasmic sperm injection (ICSI).

DESIGN

Prospective study.

SETTING

Infertility Research Center, Jeil Women's Hospital.

MAIN OUTCOME MEASURE(S)

Human semen obtained from fertile donors was prepared by one of the following methods: washing only (washed control); Percoll gradient; pentoxifylline; human follicular fluid (FF); pentoxifylline + FF; or platelet-activating factor (PAF) treatment. The AR of each group was assessed by fluorescein isothiocyanate-conjugated Pisum sativum agglutinin or Arachis hypogea agglutinin. Spermatozoa of washed control, pentoxifylline + FF, and PAF treated groups, with significantly higher AR rate than others, were injected into mature hamster oocytes. Spermatozoon-injected oocytes were cultured for 6, 9, 12, or 15 hours. Then they were stained with Toluidine blue for PN formation examination under a light microscope.

RESULT(S)

Acrosome reaction rates of washed control, Percoll gradient, pentoxifylline, FF, pentoxifylline + FF, and PAF treated groups were 10.5% +/- 2.6%, 10.3% +/- 1.7%, 16.4% +/- 1.8%, 24.8% +/- 5.6%, 28.4% +/- 3.8%, and 33.3% +/- 5.2%, respectively. Pronuclear formation rate in washed control, pentoxifylline + FF, and PAF treated groups were 5.6% (3/54), 19.0% (11/58), and 18.9% (10/53) at 6 hours; 32.7% (18/55), 51.8% (29/56), and 57.4% (31/54) at 9 hours; 36.1% (22/61), 53.6% (30/56), and 50.0% (27/54) at 12 hours; and 47.2% (25/53), 64.8% (35/54), 53.6% (30/56) at 15 hours after ICSI. Pronuclear formation rate was significantly higher in pentoxifylline + FF, and PAF treated groups than that in the washed control group at 6 and 9 hours after ICSI.

CONCLUSION(S)

Pronuclear formation of oocytes takes place faster on those that were injected with acrosome-reacted spermatozoon than those injected with acrosome-intact spermatozoon. It could be concluded that induction of the AR of spermatozoa accelerates the time of PN formation and early development of the embryo in ICSI.

Effect of pentoxifylline added to freezing media on subsequent post-thaw hypoosmotic swelling test and other semen parameters

This study evaluated the effects of pentoxifylline (PTX) on post-thaw semen parameters as well as the hypoosmotic swelling (HOS) test. Fourteen samples were evaluated for volume, count, motility, % grade A sperm, and HOS test. Two aliquots were frozen, one in freezing medium and the other in a 3 mM solution of PTX and freezing medium. Both groups were frozen in liquid nitrogen vapors for 30 min. Thawing was performed at 37 degrees C for 15 min, followed by a wash with 2 parts 0.5% HSA/MHTF to 1 part sample. Pellets were resuspended in 0. MHTF and then evaluated as described above. In addition, motility was evaluated 2 h post-thaw. Following freeze-thaw, the mean motile densities were similar (17.5 x 10 motile/mL vs. 20.4 x 10(6) motile/mL for PTX and control, respectively). Two hours post-thaw, the PTX group had a mean sperm motility of 31.3% vs. 37.7% for the control group (p > .05). There were no significant differences in % grade A sperm in PTX (13.0%) vs. control (12.0%). Similarly, HOS scores did not improve following cryopreservation (43.0% and 50.6% for PTX and control, respectively). Thus, no improvement was found by freezing sperm with PTX.

An evaluation of the effect of pentoxifylline on sperm function and treatment outcome of male-factor infertility: a preliminary study

OBJECTIVE

Our objective was to study the effect of pentoxifylline (PF) on fertilization rates in couples with previous failure of fertilization and male-factor infertility and to determine the predictive value of conventional semen analysis parameters in selecting the couples who would benefit from the elective use of PF in IVF.

DESIGN

This prospective controlled study was conducted in an assisted conception

METHODS

Sixty-nine couples with previous failed IVF cycle, who had a low fertilization rate and/or male-factor infertility, were recruited to the study. Multiple follicular development was induced using the same protocol of human menopausal gonadotropin and gonadotropin releasing hormone analogue in both cycles. The oocytes were inseminated with spermatozoa treated with PF. The fertilization rates in the PF cycle were compared to the reference cycle based on semen analysis parameters and previous fertilization rates.

RESULTS

In couples with male infertility, the fertilization rate improved significantly, from 17 to 50% in PF cycles (P < 0.001). A significant improvement in fertilization rate was also demonstrated in couples with previous poor fertilization, < 30% (P < 0.01), particularly in those with a very low fertilization rate, < 20% (P < 0.001). Although there was an overall improvement in fertilization rates in couples with male-factor infertility, there was no cutoff value in sperm motility that would make a significant difference in the impact of PF on fertilization rates.

CONCLUSION

Couples with poor fertilization rates in vitro benefit with a significant improvement in fertilization by the elective use of PF. The improvement is most significant in couples with previous complete failure of fertilization and poor fertilization rates, < 30%.

Key elements of a highly efficient intracytoplasmic sperm injection technique: Ca2+ fluxes and oocyte cytoplasmic dislocation

OBJECTIVE

To analyze the mechanism by which modifications of the intracytoplasmic sperm injection (ICSI) technique influence success rates.

DESIGN

Prospective clinical study supplemented with an experimental analysis of Ca2+ fluxes provoked by the injection procedure.

SETTING

Private hospital and public research center.

PATIENTS

Patients treated by IVF and ICSI.

INTERVENTIONS

Intracytoplasmic sperm injection.

MAIN OUTCOME MEASURES

Fertilization and pregnancy rates and intracellular free Ca2+ concentration.

RESULTS

The inclusion of vigorous aspiration of oocyte cytoplasm improved outcomes of ICSI. In a series of 100 consecutive cases treated with this technique, the fertilization and pregnancy rates were 87% of total metaphase II oocytes injected and 52% of total treatment cycles, respectively. Enhanced Ca2+ influx into the injected oocytes and dislocation of the oocyte cytoplasm, including the development of a focus of persistent Ca2+ discharge around the injected sperm head, were the main characteristics of this highly successful technique.

CONCLUSIONS

Vigorous aspiration of oocyte cytoplasm may facilitate fertilization after ICSI by increasing the oocyte Ca2+ load at the time of injection, by establishing a more intimate contact of the injected sperm head with oocyte intracellular Ca2+ stores, or by a conjunction of these mechanisms.

The effect of alpha-amylase on the acrosomal membrane of human sperm

PURPOSE

Sperm capacitation and the acrosome reaction are prerequisites to accomplishing fertilization. The object of this research was to induce capacitation and the acrosome reaction of human sperm, comparing the acrosome status of fertile and infertile men, using alpha-amylase.

METHODS

Acrosome status was measured using indirect immunofluorescence (IIF; monoclonal antibody GB24, Thèramex), hemizona assay (HZA), and transmission electron microscopy (TEM).

RESULTS

Acrosome-reacted sperm without alpha-amylase treatment was significantly more abundant in the fertile versus the infertile group utilizing IIF, HZA, and TEM. alpha-Amylase-treated spermatozoa from the fertile and infertile groups showed a significant increase in the number of sperm bound to the hemizona (P < 0.05).

CONCLUSIONS

The percentage of acrosome-reacted sperm in the infertile group was significantly enhanced by alpha-amylase, utilizing IIF and TEM.

Cumulus removal and addition of follicular fluid possibly improves pregnancy rates with in vitro fertilization for male factor

This study evaluated the use of in vitro fertilization (IVF) for patients with subnormal semen parameters without the use of micromanipulation. All patients were characterized as having male factor as follows: normal morphology (NM) < or = 10% according to strict criteria [15] and motile density (MD) < or = 10 x 10(6)/mL. Strict morphology was divided into three groups: group I (n = 72), < or = 2% group II (n = 24), 3-5%; and group III (n = 29), 6-10%. Modification of standard IVF techniques included manual cumulus removal (CR) from oocytes, pooling up to ten oocytes together in 1 mL of media, and supplementing media with 20% human follicular fluid (FF). Rates of fertilization and pregnancy were compared. The overall fertilization rate (FR) was 57.7% and the pregnancy rate (PR) per retrieval cycle was 14.8%. There was no significant improvement in the fertilization or PRs when IVF was modified using CR and FF, although the FR was higher in group I for patients who received the modified procedures. In patients with < or = 5 x 10(6) sperm/mL, there were no pregnancies in five cycles and four transfers following the conventional method, but two sets of twins with the modified protocols in seven cycles. Clinical pregnancies were achieved with male factor without the need for micromanipulation. The most severe cases were automatically assigned to modified IVF techniques, e.g., CR with or without FF. Prospective randomized studies are needed to determine if modified procedures are superior to conventional therapy.

Acrobeads test using monoclonal antibody-coated immunobeads: clinical application

Acrosome-reacted sperm was examined in infertile and fertile males using the Acrobeads test. The Acrobeads score was significantly higher in fertile males than in infertile males with normal or abnormal seminal findings (p < .005 and p < .001, respectively). The Acrobeads score was 2 or more in all the fertile males, but 62% of the infertile males with abnormal seminal findings (p < .02). Therefore, a disturbance in the acrosome reaction is suggested to be one of the causes of decreased fertility potential. A high correlation was found between Acrobeads score and sperm motility (r = .46, p < .001) or motile sperm concentration (r = .51, p < .0001). The Acrobeads test, the results of which reflect the acrosome condition of the sperm, is useful in the assessment of sperm function related to fertility.

Alleviation of acrosome reaction prematurity by sperm treatment with egg yolk

OBJECTIVE

To examine the effects of egg yolk on the spontaneous and ionophore-induced acrosome reaction (AR) and sperm-zona pellucida (ZP) binding in spermatozoa from patients with AR prematurity.

DESIGN

Prospective analysis.

SETTING

Private hospital, public research center, and a university-based laboratory.

PATIENTS

In vitro fertilization patients selected on the basis of previous AR testing.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Frequency of the AR, number of ZP-bound spermatozoa.

RESULTS

The pretreatment of spermatozoa with egg yolk decreased the frequency of AR occurring spontaneously during subsequent sperm incubation in capacitating medium but did not modify the sperm response to ionophore. The egg yolk-treated spermatozoa also showed a greater capacity of binding the ZP than their untreated counterparts.

CONCLUSIONS

The pretreatment of spermatozoa with egg yolk alleviates the sperm-ZP binding deficiency resulting from premature initiation of the AR and may be helpful in IVF with patients showing this anomaly.

Effect of pentoxifylline on experimentally induced lipid peroxidation in human spermatozoa

We demonstrated previously that pentoxifylline in millimolar concentrations can inhibit superoxide anion production by human spermatozoa. In the present study we have examined the effects of the same concentrations of pentoxifylline on experimentally induced lipid peroxidation, as measured by malondialdehyde formation in the thiobarbituric (TBA) assay. Under the experimental conditions used, preincubation of spermatozoa with pentoxifylline led to a significant dose-dependent stimulation (p < 0.005) of malondialdehyde production amounting to 10.77 +/- 2.35%, 13.45 +/- 2.99% and 17.4 +/- 1.99% (mean +/- SEM) for 1.9, 3.7 and 11.2 mmol/l pentoxifylline, respectively. In the presence of 11.2 mmol/l pentoxifylline, an increase in iron-catalysed lipid peroxidation potential was detected in samples of spermatozoa from 29 infertile men, regardless of their initial levels of malondialdehyde. The results of this study indicate that pentoxifylline might further augment the ferrous ion-stimulated decomposition of pre-accumulation lipid hydroperoxides in the sperm plasma membrane and thus promote malondialdehyde generation in the TBA assay. It is concluded that the stimulatory effect of pentoxifylline on iron-induced lipid peroxidation may have an adverse effect on the quality of sperm suspensions prepared for in vitro fertilization, a possibility which should be investigated further.

Effects of pentoxifylline on human sperm parameters in vitro

PURPOSE

Pentoxifylline was tested in three raising concentrations (0.7 mM/l, 1.5 mM/l, 3.6 mM/l) on human sperm cells in vitro.

METHODS

On 143 samples, we examined drug effect on motile sperm concentration, grade of their motility, acrosome reaction and membrane status.

RESULTS

Obtained results show improvement in motile sperm concentration, as well as in the grade of progression in the majority of samples.

CONCLUSIONS

Spermatozoa membranes as well as occurrence of the acrosomal reaction were not affected by pentoxifylline.

Pentoxifylline acts synergistically with A23187 to increase the penetration of zona-free hamster oocytes by cryopreserved human spermatozoa

The number of cryopreserved human spermatozoa which penetrated zona-free hamster oocytes after stimulation with 2 mumol A23187 per litre was increased by the further addition of 0.6 or 3.6 mmol pentoxifylline per litre. With spermatozoa prepared by washing by repeated centrifugation, the median numbers of sperm heads/egg were 1.9, 7.9 and 10.8 in the presence of 0, 0.6 or 3.6 mmol pentoxifylline per litre, respectively. A similar effect was observed with spermatozoa prepared on a Percoll gradient. As A23187 inhibited sperm motility, and this was exacerbated by pentoxifylline, the increased penetration rate of hamster oocytes cannot be explained by improved sperm motility. The number of spermatozoa stimulated to acrosome react by 2 mumol A23187 per litre was increased 3-fold by 3.6 mmol pentoxifylline per litre and 4-fold by 5 mmol caffeine per litre. These data suggest that cAMP may act synergistically with Ca2+ to stimulate the acrosome reaction. Pentoxifylline may improve the fertility of poor-quality human spermatozoa by enhancing their ability to respond to the Ca2+ signal produced by binding to the zona pellucida.

Variability of the response to pentoxifylline in vitro in infertile normozoospermic and asthenozoospermic patients

The in vitro effect on the motility of spermatozoa of the methylxanthine pentoxifylline was studied in 30 patients consulting for infertility (13 normozoospermic and 17 asthenozoospermic). After separation by centrifugation on Percoll gradient, the spermatozoa were incubated for 30 min in pentoxifylline (3.6 mM), then the pentoxifylline was removed by washing and centrifugation. The residual effect of pentoxifylline was studied by computer-assisted videomicrographic analysis of the sperm motion parameters. In both groups of patients a decrease in the percentage of motile spermatozoa after exposure to pentoxifylline was observed, as compared with a control group. The effect on the motion parameters varied according to the time of observation (30, 120, 240 min). In the asthenozoospermic patients, the curvilinear velocity (VCL) was not modified in a statistically significant manner. In the normozoospermics, the VCL was increased after exposure to pentoxifylline at 120 min (p = .03) and 240 min (p = 10(-5)); similarly, the amplitude of the lateral head displacement (ALH) was greater in this group at 120 and 240 min (p = .01 for maximum ALH). However, a heterogeneity was noted in the response between individuals, which required that the statistical analyses take into account these differences.

Use of the acrosome reaction to ionophore challenge test in managing patients in an assisted reproduction program: a prospective, double-blind, randomized controlled study

OBJECTIVE

To assess the utility of the acrosome reaction (AR) to ionophore challenge test in determining the sperm treatment protocols for patients undergoing assisted reproduction.

DESIGN, SETTING, PATIENTS

One hundred twenty-one couples undergoing an IVF-ET or GIFT procedure from January to July 1992 were included in this prospective study. All cases had a preliminary semen analysis within the previous 3 months and an AR to ionophore challenge test was carried out unless an acceptable fertilization rate occurred on previous IVF. For those patients whose AR to ionophore challenge score was below the accepted fertile range of > or = 10%, a second AR to ionophore challenge test was performed after exposure of sperm to the stimulant pentoxifylline. Couples then were managed by assisted reproduction with randomized allocation of oocytes for fertilization with a standard sperm preparation or with added sperm stimulants, either 3.6 mM pentoxifylline alone or combined with 3.0 mM 2-deoxyadenosine. The study was double-blind with neither the patients nor the embryologist knowing the AR to ionophore challenge result at the time of the IVF procedure.

MAIN OUTCOME MEASURES

Data from the preliminary semen analyses and AR to ionophore challenge scores were correlated with the fertilization rates achieved using control and treated sperm preparations. The rates of total fertilization failure and the numbers of clinical pregnancies occurring in each subgroup were also recorded.

RESULTS

All AR to ionophore challenge groups showed normal sperm counts except the groups with poor AR to ionophore challenge, which demonstrated reduced sperm counts. The group with normal AR to ionophore challenge scores or previous normal fertilization showed satisfactory fertilization rates with either control or treated sperm, although some individual cases showed reduced fertilization with treated sperm. The fertilization rate for the group with low AR to ionophore challenge scores improved significantly with pentoxifylline, and the benefit was greatest when this had been predicted from the AR to ionophore challenge studies. Cases with persisting poor AR to ionophore challenge despite pentoxifylline showed no significant improvement in fertilization rates with sperm exposed to either sperm stimulant regimens. Poor AR to ionophore challenge scores were also predictive of total fertilization failure, but this problem was reduced by sperm stimulation. The AR to ionophore challenge score at 10% cutoff level showed optimal levels of sensitivity (82.1%), highest negative predictive value (82.1%), and lowest false negative rate (17.9%).

CONCLUSIONS

The AR to ionophore challenge test is useful in the assessment and management of the male factor in assisted reproduction. It can be used to identify the majority of cases who will benefit from the use of sperm stimulants.

Most living acrosome-reacted spermatozoa do not fuse with the oocyte when inserted into the perivitelline space

OBJECTIVE

To evaluate the frequency with which acrosome-reacted spermatozoa fuse with the oocyte after subzonal insemination (SUZI).

DESIGN

The acrosome reaction frequency determined in sperm suspensions used for SUZI was related with the frequency of sperm-oocyte fusion after the microinsemination procedure. In some experiments, the acrosome reaction frequency was compared in sperm suspensions aspirated into the microinjection needle and in those leaving the needle.

SETTING

Private hospital, public research center, and university-based laboratory.

PATIENTS, PARTICIPANTS

Patients involved in a program of micromanipulation-assisted fertilization and healthy sperm donors.

INTERVENTIONS

IVF-ET.

MAIN OUTCOME MEASURES

Frequency of the acrosome reaction, frequency of sperm-oocyte fusion.

RESULTS

The procedure of sperm aspiration to the microinjection needle followed by active swim-out of motile spermatozoa did not change the overall percentage of acrosome-reacted spermatozoa even though the subpopulation of acrosome-reacted spermatozoa leaving the needle was enriched in recently reacted cells. The frequency of sperm-oocyte fusion was considerably lower than the frequency of the acrosome reaction in both patient and donor sperm samples, irrespective of the number of spermatozoa inserted per egg.

CONCLUSIONS

A spontaneous acrosome reaction does not necessarily predispose a spermatozoon to fuse with the oocyte after SUZI. It remains to be elucidated whether this relative inefficiency of acrosome-reacted spermatozoa is related to technical aspects of SUZI or whether, in a more general sense, the acrosomal exocytosis and the development of sperm-oocyte fusion capacity are distinctly regulated, though closely related, phenomena.

Fertilization failure after subzonal sperm insertion associated with defective fusional capacity of acrosome-reacted spermatozoa

A case of an isolated impairment of the ability of acrosome-reacted spermatozoa to fuse with the oocyte is reported. This impairment was associated with fertilization failure after subzonal sperm insertion even though elevated numbers of spermatozoa were inserted per oocyte. This observation shows the need for further studies into the relationship between the acrosome reaction and the sperm-oocyte fusion to better understand the advantages and the limitations of subzonal sperm insertion in different types of sperm pathology.