The effect of the motility stimulants, caffeine, pentoxifylline, and 2-deoxyadenosine on hyperactivation of cryopreserved human sperm**Presented in part at the 23rd Annual Conference of the Australian Society for Reproductive Biology, Sydney, New South Wales, Australia, September 30 to October 2, 1991

Action of swim-up and caffeine on equine frozen sperm

Cryopreservation of equine semen is crucial to semen commercialization. However, it reduces sperm motility and longevity. Thus, sperm selection methods and addition of motility-activating substances to sperm, such as caffeine, may improve sperm quality of equine frozen semen. The objective of the current work was to evaluate the effects of caffeine on recovery and quality parameters of frozen-thawed sperm subjected to swim-up selection to be used in intracytoplasmic sperm injection (ICSI) in assisted reproductive techniques. Stallion semen were frozen and after thawing different caffeine concentrations were added to the samples performing four treatments control (no caffeine), 3, 5, and 7.5 mM caffeine. Sperm kinematic and motility were assessed by computer-assisted sperm analysis (CASA). Then, the four treated samples were submitted to the swim-up sperm selection, and the number of recovered sperm and morphology were evaluated at four times 20, 40, 60, and 80 min. The swim-up increased the recovery proportion of normal morphology sperm without (80.1±1%) or with caffeine addition (3mM: 81.2±1%, 5mM: 79.9±1% and 7.5 mM 78.9±1%) compared to the thawed semen (70±2%). However, the addition of 5 mM caffeine induced an increase in sperm motility (38.9±2.8 vs. 32.6±3.4%, P<0.05), and sperm recovery after swim-up (7.9x10⁶ vs. 3.4x10⁶ sperm/ml, P<0.05) compared to the control. The addition of 5 mM caffeine to frozen-thawed equine semen before swim-up selection improved sperm motility and increased the sperm recovery rate while not decreasing the percentage of morphologically normal sperm. Thus, caffeine addition to frozen-thawed equine semen before swim-up selection has potential clinical application in improving sperm quality for use in ICSI.

IGF-I and NGFβ enhance in vitro progressive motility and vitality of human spermatozoa

PURPOSE

Progressive motility (PM) and vitality are positively associated with fertilization ability of spermatozoa. Here, the effects of IGF-I and NGFβ on PM and vitality of human spermatozoa were investigated.

METHODS

Forty-three volunteers gave semen samples after 2-3 days of sexual abstinence. Each sample was processed with density gradient centrifugation and sperm washing. The pellet was divided into 3 aliquots. An aliquot containing one million of progressively motile spermatozoa was incubated for an hour (37°C) in standard culture medium (control group), and two aliquots with the same number of progressively motile spermatozoa were incubated in medium supplemented with IGF-I or NGFβ. Two concentrations of IGF-I (100 ng/ml and 1000 ng/ml) and NGFβ (0,5 ng/ml and 5 ng/ml) were tested.

RESULTS

Both growth factors significantly increased PM and vitality in comparison with control either at the low or the high concentration. IGF-I seemed to be more effective than NGFβ. The effects did not seem to be dose dependent with the exception of the effect of IGF-I on vitality.

CONCLUSIONS

The enhancement of PM and vitality of human spermatozoa by IGF-I and NGFβ opens new ways for the improvement of sperm processing. Further research is needed to determine the most effective concentrations.

Caffeine increased progressive motility of human spermatozoa in normozoospermic and asthenozoospermic semen samples and enhanced activity of seminal creatine kinase

Even though the effect of caffeine on humans' health has been revealed in various research studies, its effect on semen quality has yet to be well explained. Here, we measured the effect of caffeine at 1, 5, 10 and 20 mM on motility of human spermatozoa in normozoospermic and asthenozoospermic semen samples, level of seminal nitric oxide, chelation of seminal calcium ions and activity of seminal creatine kinase. Fifty-one normozoospermic and ten asthenozoospermic semen samples were recruited in this study. Sperm motility was evaluated by Makler counter, and seminal nitric oxide, seminal-free calcium and activity of seminal creatine kinase were measured spectrophotometrically. Caffeine at 10 mM significantly (p < .05) increased progressive motility of spermatozoa in both tested groups. Also, caffeine significantly increased (p < .05) activity of creatine kinase and insignificantly (p > .05) altered nitric oxide and free calcium levels in seminal plasma. In conclusion, progressive motility of human spermatozoa was found to be higher in the presence of caffeine at 10 mM in normozoospermic and asthenozoospermic semen samples; this increase, albeit partially, could be due to increased activity of seminal creatine kinase, but not to increased production of nitric oxide or chelation of free calcium ions.

Current Insights and Latest Updates in Sperm Motility and Associated Applications in Assisted Reproduction

Spermatozoon is a motile cell with a special ability to travel through the woman’s reproductive tract and fertilize an oocyte. To reach and penetrate the oocyte, spermatozoa should possess progressive motility. Therefore, motility is an important parameter during both natural and assisted conception. The global trend of progressive reduction in the number and motility of healthy spermatozoa in the ejaculate is associated with increased risk of infertility. Therefore, developing approaches for maintaining or enhancing human sperm motility has been an important area of investigation. In this review we discuss the physiology of sperm, molecular pathways regulating sperm motility, risk factors affecting sperm motility, and the role of sperm motility in fertility outcomes. In addition, we discuss various pharmacological agents and biomolecules that can enhance sperm motility in vitro and in vivo conditions to improve assisted reproductive technology (ART) outcomes. This article opens dialogs to help toxicologists, clinicians, andrologists, and embryologists in understanding the mechanism of factors influencing sperm motility and various management strategies to improve treatment outcomes.

A model protocol for the cryopreservation and recovery of motile lizard sperm using the phosphodiesterase inhibitor caffeine

Reproductive technologies such as genome storage and assisted reproduction have a significant role to play in ending or reversing species extinctions. However, such technologies for non-model organisms (i.e. non-mammalian species) are poorly developed. This is particularly true for the reptiles, in which there is a dearth of successful protocols for cryopreserving reptile spermatozoa, despite limited attempts. We investigated sperm cryopreservation in the Australian lizard Varanus panoptes with the objective of addressing the unmet need for an optimized cryopreservation protocol for the spermatozoa of squamate reptiles. We tested the efficacy of two cryoprotectants [dimethyl sulfoxide (DMSO) and glycerol] as well supplementation with a phosphodiesterase inhibitor (caffeine) to promote post-thaw motility. For cryopreservation, sperm were cooled in straws suspended in liquid nitrogen vapour for 5 minutes (approximately -135°C), before being plunged into liquid nitrogen (approximately -196°C), and later thawed in a water bath at 35°C. Samples were incubated post-thaw for 10 minutes in the presence or absence of 10 mM of caffeine. Both cryoprotectant type and concentration significantly affected percent sperm motility pre-freezing, with DMSO being less cytotoxic than glycerol and motility decreasing at higher concentrations of both cryoprotectant types. While cold shock did not significantly affect sperm motility, both cryoprotectant type and concentration did significantly impact the motility of post-thawed spermatozoa. Thus, mid-range concentrations (10% v/v) of DMSO and glycerol yielded a greater post-thaw motility compared with 5 and 20% v/v, while DMSO proved superior to glycerol. The addition of caffeine resulted in a significant recovery of post-thaw motility for both cryoprotectants, with higher rates of motility being associated with higher cryoprotectant concentrations. These protocols provide a significant step forward for in situ and ex situ management of threatened reptiles and add to recent evidence that reptilian sperm may have the full range of phosphorylation-mediated cellular mechanisms associated with capacitation, motility and metabolic regulation found in mammalian sperm.

The Effect of Different Concentrations of Caffeine, Pentoxifylline and 2’-Deoxyadenosine on the Biological Properties of Frozen-Thawed Canine Semen

Artificial insemination (AI) and semen cryopreservation are the most accessible and commonly used techniques for breeding domestic animals. Among many parameters, such as plasma membrane integrity and acrosome structure, one of the key factors that determine the quality of frozen-thawed samples for artificial insemination is sperm motility. Sperm motility is one of the key parameters that determine the quality of frozen-thawed samples for AI. The total number of progressively motile spermatozoa in thawed canine semen is correlated with fertility. A variety of substances were used to compare sperm motility with the control. The aim of this study was to determine the effect of semen extender supplementation with motility stimulants, pentoxifylline (PTX), caffeine (CAF) and 2’-deoxyadenosine (DX), after different post-thaw incubation times (30, 60, 120 min) on the motility, selected kinematic parameters, plasma membrane integrity and mitochondrial membrane potential of cryopreserved canine spermatozoa. During attempts to improve the quality of cryopreserved semen, the applied substances exerted beneficial effects at a concentration of 10 mM. We demonstrated that both phosphodiesterase inhibitors, caffeine and pentoxifylline, as well as 2’-deoxyadenosine increased the motility and selected kinematic parameters of thawed canine spermatozoa.

Spermatozoa as Functional Components of Robotic Microswimmers

In recent years, the combination of synthetic micro- and nanomaterials with spermatozoa as functional components has led to the development of tubular and helical spermbots - microrobotic devices with potential applications in the biomedical and nanotechnological field. Here, the initial advances in this field are discussed and the use of spermatozoa as functional parts in microdevices elaborated. Besides the potential uses of these hybrid robotic microswimmers, the obstacles along the way are discussed, with suggestions for solutions of the encountered challenges also given.

Pentoxifylline improves sperm capacitation and in vitro fertilization of oocytes in the golden hamster

Pentoxifylline (PF) is used to improve motility of spermatozoa from subfertile or nonfertile males to accomplish in vitro fertilization in humans. The possible adverse effect of PF on pre- and peri-implantation stage embryo development in a suitable rodent model, such as the golden hamster, is yet to be determined. In this study, hamster cauda epididymal spermatozoa were exposed to different concentrations (0.23 to 3.6 mM) of PF, and their quantitative [percentage of motility] and qualitative [Score 0 to 5] motility were assessed and values expressed as the sperm motility index. Upon addition of spermatozoa to dishes containing PF, an immediate increase in sperm motility and sperm motility index was evident, which increased up to 4 to 6 h and then declined. The sperm motility index increase by PF was dose-dependant, and >or= 1.8 mM PF was detrimental after 4 h. The optimum dose of PF was found to be 0.45 mM. To assess the fertilizing ability of PF-treated spermatozoa, in vitro fertilization was carried out. Fertilization rates for spermatozoa treated with 3.6 mM PF were lower (53.8 +/- 7.8) than for the controls (69.5 +/- 10.2), whereas treatment with 0.45 mM PF increased the rates (91.6 +/- 4.3) compared with that of the controls (80.2 +/- 5.9). In conclusion, low concentrations (0.23 to 0.45 mM) of PF improve sperm capacitation and fertilization of oocytes in vitro in the golden hamster.

Intracytoplasmic sperm injection with motile and immotile frozen-thawed testicular spermatozoa (the Hungarian experience)

The authors summarize their experience in 75 in vitro fertilization cycles, where frozen-thawed testicular spermatozoa were used for intracytoplasmic sperm injection. In 32 cases, motile spermatozoa could be observed in the frozen-thawed sample. In 34 cases, motility could be induced by pentoxifylline and in nine cases immotile spermatozoa, selected with hypoosmotic swelling test, were used for fertilization. The fertilization rates obtained with motile and immotile spermatozoa (66.1% versus 52.3%) were not significantly different. Our data demonstrate that freezing of testicular spermatozoa opened new possibilities for the treatment of azoospermic men. The clinical pregnancy rate per embryo transfer (ET) (21.87%) was comparable with previous results use of fresh testicular spermatozoa (27.7%). The quality and number of transferred embryos had the most significant impact on the pregnancy rate. The fertilization rate and frequency distribution of good-quality embryos were lower in the case of immotile spermatozoa, and pregnancies were only achieved when motile spermatozoa had been used.

Calcium Channels and Ca2+ Fluctuations in Sperm Physiology

Generating new life in animals by sexual reproduction depends on adequate communication between mature and competent male and female gametes. Ion channels are instrumental in the dialogue between sperm, its environment, and the egg. The ability of sperm to swim to the egg and fertilize it is modulated by ion permeability changes induced by environmental cues and components of the egg outer layer. Ca(2+) is probably the key messenger in this information exchange. It is therefore not surprising that different Ca(2+)-permeable channels are distinctly localized in these tiny specialized cells. New approaches to measure sperm currents, intracellular Ca(2+), membrane potential, and intracellular pH with fluorescent probes, patch-clamp recordings, sequence information, and heterologous expression are revealing how sperm channels participate in fertilization. Certain sperm ion channels are turning out to be unique, making them attractive targets for contraception and for the discovery of novel signaling complexes.

Growth hormone or insulin-like growth factor-I extends longevity of equine spermatozoa in vitro

Growth hormone (GH) and insulin-like growth factor-I (IGF-I) are both present in blood plasma and IGF-I has been measured in epididymal fluid and seminal plasma. This study was designed to investigate the direct effects of GH or IGF-I on the motility of mature equine spermatozoa in vitro. We compared the effects of one concentration (100 ng/ml) of recombinant bovine GH (rbGH) and recombinant human IGF-I (rhIGF-I) on motility and motion characteristics of equine spermatozoa over a 24 h period. Motility was maintained longer in spermatozoa treated with either rbGH or rhIGF-I during a 24 h period at room temperature (P < 0.05). Spermatozoa motion characteristics at time 0, 1, 2, 4, 6, 12 and 24 h for both rbGH and rhlGF-I were not significantly different from the respective controls. This study has shown that GH and IGF-I are effective in promoting the in vitro longevity of spermatozoa.

Influence of pentoxifylline on sperm membrane functional integrity

In epididymal mouse spermatozoa, the effects of dibutyryl cyclic adenosine monophosphate 1 mmol/L (dbcAMP), pentoxifylline 5 mmol/L (PX), and/or mastoparan 50 mumol/L (MT) were evaluated for the following parameters: percentage of motile cells and response to hypoosmotic shock (HOS). The gametes were incubated during 80 min (A) or 200 min (B) in Tyrode's medium, and the drugs were added during the last 20 min. In A, dbcAMP + PX (61.5 +/- 5.4%; n = 10) enhanced and MT decreased significantly the population of motile cells (13.4 +/- 5.4%; n = 6) (control: 47.6 +/- 3.9%; n = 11). In B, PX significantly increased this parameter and MT plus PX also exerted a significant detrimental effect. Responses to HOS dropped significantly in the presence of PX + MT in A or in B; in this latter condition a similar decrease was evoked by MT alone. A positive correlation between percentages of swollen and motile spermatozoa was detected in A or in B in samples incubated with PX (r = .58, n = 11 and r = .76, n = 10; p < .05, respectively). These results that support that, in mouse sperm tail, PX would preserve functional membrane integrity, a relevant condition for adequate motility.

Male infertility. Evaluation and nonsurgical therapy

Male infertility is a complicated and often poorly understood pathologic process. The cause of a man's infertility frequently remains unknown even after a thorough evaluation. Many of the currently available medical therapeutic options are empirical and lack documentation of efficacy. New diagnostic tests are emerging that may help define some previously obscure causes of infertility. Only when these abnormalities have been clearly identified will more specific and cost-effective treatment regimens be instituted.

The effect of 12-myristate 13-acetate phorbol ester on human sperm hyperactivation

OBJECTIVE

To determine whether 12-myristate 13-acetate phorbol ester (PMA) can increase hyperactivated motility of human sperm.

DESIGN

A controlled pharmacological study using computer-assisted semen analysis.

SETTING

Andrology laboratory in a medical research institution.

PATIENT(S)

Normal semen was obtained from 48 men.

INTERVENTION(S)

Washed sperm were exposed to different concentrations of PMA alone or with P and pentoxifylline (PTX) for up to 2 hours and sperm motility measured by a computer-assisted semen analyzer.

MAIN OUTCOME MEASURE(S)

The percentage of sperm with hyperactivated motility was determined from the motility parameters: curvilinear velocity, linearity, and maximum amplitude of lateral head displacement.

RESULT(S)

Phorbol ester PMA increased hyperactivated motility in a dose- and time-dependent manner. At 1 hour, the average increases in hyperactivated motility were as follows: 2 microM, 4.8% +/- 1.5%; 6 microM, 9.6% +/- 1.5%; and 20 microM, 11.3% +/- 2.2%. The PMA effect was not altered when P or PTX were added although each separately had a positive effect on hyperactivation.

CONCLUSION(S)

Phorbol ester PMA stimulates human sperm hyperactivated motility, indicating the involvement of protein kinase C in the signal transduction pathway.

Influence of artificial stimulation on unprocessed and Percoll-washed cryopreserved sperm

The ability of pentoxifylline and 2-deoxyadenosine to stimulate sperm motility and motion characteristics was assessed in unprocessed and processed (Percoll-separated) cryopreserved specimens. Specimens from 12 healthy volunteers were obtained, and the motion characteristics were analyzed; half the sample was immediately cryopreserved and the other was washed using the Percoll gradient technique. To study stimulation, samples were thawed and divided into four aliquots: One was used as a control, and the others were incubated with 2.5 mM 2-deoxyadenosine, 2.5 mM pentoxifylline, or 5.0 mM pentoxifylline for 60 min. Sperm characteristics were analyzed on a sperm motion analyzer at 0 and 60 min incubation. In both unprocessed and processed samples, percentage motility improved significantly after stimulation with 2-deoxyadenosine or pentoxifylline (p = .003 or p = .0002, respectively); other characteristics improved to varying extent after 2-deoxyadenosine or pentoxifylline stimulation. Comparison after stimulation revealed that sperm motion characteristics in the unprocessed specimen were similar to sperm motion characteristics in the processed group.

Could in vitro fertilization with a modified sperm preparation technique be an option to micromanipulations?

PURPOSE

This study evaluated the efficiency of in vitro fertilization with a modified sperm preparation technique for male infertility, to avoid systematic recourse to ICSI.

METHODS

The sperm function stimulants pentoxifylline, 2-deoxyadenosine, and follicular fluid were used during the sperm preparation of IVF trials for two groups of patients: couples with long-standing infertility and previous IVF failures and couples with male-factor infertility scheduled for their first treatment.

RESULTS

Forty-nine attempts were performed in the first group. The overall fertilization rate (percentage of zygotes with two pronuclei 18 hr after sperm insemination) was 30% and the clinical pregnancy rate per transfer was 33%. For the second group, 30 attempts were performed. The fertilization rate was 29.6% and the clinical pregnancy rate was 62.5% per transfer. The total number of recovered motile sperm appears to be a significant parameter: a cutoff value of 0.25 million motile sperm recovered after capacitation treatment has a good prognostic value for choosing between IVF with sperm enhancers and ICSI.

CONCLUSIONS

The described modified IVF could constitute an alternative to the systematic use of ICSI.

Sperm kinematics of cryopreserved normozoospermic specimens after artificial stimulation

OBJECTIVES

Cryopreservation of semen is associated with reduced motility after thawing, resulting in a decreased pregnancy rate. Artificial stimulation of motility has been used in fresh semen samples. This study measured the effect of motility stimulants on various motion characteristics and other sperm functions using cryopreserved semen.

METHODS

Frozen semen samples from healthy donors were thawed, and motility stimulants were added in vitro and incubated for 60 minutes. The percentages of motile spermatozoa in each specimen and other motion characteristics were measured. In addition, spermatozoon's viability, membrane integrity, and ability to penetrate bovine cervical mucus were studied after addition of stimulants.

RESULTS

Percentage motility and all other motion characteristics improved after stimulation with pentoxifylline, caffeine, or 2-deoxyadenosine. Linearity did not significantly differ in the control samples after adding any of the stimulants. Viability, membrane integrity, and penetration ability did not improve significantly and were comparable with control values.

CONCLUSIONS

Pentoxifylline, caffeine, and 2-deoxyadenosine can stimulate sperm motility and other motion characteristics. This may be beneficial in the cryopreservation of sperm from normal donors and oligozoospermic patients for use in assisted reproduction.

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%.

Successful use of pentoxifylline in male-factor infertility and previous failure of in vitro fertilization: a prospective randomized study

OBJECTIVE

Our objective was to determine whether the use of pentoxifylline (PF) would improve the in vitro fertilization (IVF) rate and outcome in couples with male factor infertility and previous failure of fertilization in vitro.

DESIGN

This prospective randomized controlled study was conducted in an assisted conception unit.

MATERIALS AND METHODS

Forty-nine couples with previous failed fertilization in vitro attributable to male factor or male-factor infertility without previous IVF were recruited for the study. Controlled ovarian hyperstimulation was performed using a combination of gonadotropin releasing hormone agonist and human menopausal gonadotropin. Oocytes of the same grade and maturity were inseminated with spermatozoa treated with PF or control spermatozoa. A maximum of three embryos was replaced after 48 hr and all other embryos were cryopreserved. Pregnancy outcome was followed up and evidence of fetal or neonatal anomalies reported.

RESULTS

A significantly higher fertilization rate occurred in the group where oocytes were inseminated with spermatozoa treated with PF compared with controls (56.3 versus 30.7%; P < 0.05). Fertilization occurred in 45 of the 49 cycles (92%). In seven cycles, only the oocytes that were inseminated with spermatozoa treated with PF fertilized, in contrast to only one cycle where the oocytes inseminated with control sperm fertilized (P < 0.05). Fifty-seven PF and 31 control embryos were replaced and 11 clinical pregnancies occurred. Three of the pregnancies occurred in the seven cycles in which only PF embryos were replaced, one in the single cycle where control embryos were replaced and seven from the 37 cycles in which both PF and control embryos were replaced. There was no evidence of congenital malformations in any of the offsprings resulting from this study.

CONCLUSION

This study suggests that PF improves the fertilization rate and outcome in couples with male factor infertility and poor fertilization rates. This study does not suggest any increase in teratogenicity or evidence of congenital malformations in pregnancies following IVF cycles where PF was used.

Functional motion changes during sperm transit to the site of fertilization and in-vitro applications: a review

Continued research to define the parameters of sperm function should aid the evaluation of various approaches in infertility as well as the efficacy of contraceptives for men which do not necessarily achieve azoospermia. Many treatment forms have been advocated for male factor infertility but have yielded little effect. These included, for example, gonadotrophins, clomiphene citrate, the weakly androgenic steroid, mesterolone. Often, improvements in oligoasthenozoospermia that are not related to genital infection, do not attain normozoospermic levels. Owing to lack of success with various treatment modalities, assisted reproductive technology encompassing artificial insemination by husband or donor following in vitro enhancement of sperm function have assumed an important role in male infertility. Agents that have been shown to induce and support sperm capacitation processes such as hyperactivation, could serve an important role. These include human follicular fluid (HFF), maternal serum, fetal cord serum and methyl xanthine derivatives.

The effect of pentoxifylline on sperm motility, oocyte fertilization, embryo quality, and pregnancy outcome in an in vitro fertilization program

OBJECTIVE

To study the effect of pentoxifylline on sperm motility, oocyte fertilization, embryo cleavage, and quality as well as pregnancy outcome on asthenospermic patients participating in an IVF program.

DESIGN

Prospective randomized study.

SETTING

Private IVF unit.

PATIENTS

Ninety-seven couples, 24 of whom were repeating IVF. Two semen specimens were obtained from each patient and each specimen was divided equally into two parts, nontreated (control semen) and pentoxifylline-treated (treated semen).

MAIN OUTCOME MEASURE

Sperm progressive motility, oocyte fertilization.

RESULTS

Overall and progressive motility did not differ significantly between the two semen specimens. There was a significant increase in the progressive motality of the pentoxifylline-treated semen compared with control semen. No significant difference was noticed between control and treated semen in fertilization rate, cleavage rate, embryo quality, and pregnancy rate. The percentage of patients who fertilized only with control semen (9.3%) was not significantly different from that of patients who fertilized only with treated semen (10.3%). Couples who were repeating IVF did not show significant difference in fertilization between the present study and previous attempts.

CONCLUSION

Our results showed that although the sperm progressive motility is improved after pentoxifylline treatment, it is doubtful whether this effect is of any clinical significance.

In vitro fertilization in couples with previous fertilization failure using sperm incubated with pentoxifylline and 2-deoxyadenosine

OBJECTIVE

To evaluate whether incubation of spermatozoa with both pentoxifylline and 2-deoxyadenosine would improve fertilization rates in couples with previous IVF failure.

DESIGN

Autocontrolled design in which sibling oocytes were inseminated at random in vitro with spermatozoa treated or not treated by pentoxifylline and 2-deoxyadenosine.

MEAN OUTCOME MEASURES

Oocyte quality, sperm motility, fertilization in vitro, and embryo quality.

RESULTS

Sperm motility was found optimized by metabolic stimulation using pentoxifylline and 2-deoxyadenosine. The mean fertilization rate per patient was 33.1% in the treatment group compared with 37.0% in the control group. The mean cleavage rate per patient was 79.6% for treatment versus 68.7% for control embryos. No differences in embryo quality were noted.

CONCLUSION

The results of this study demonstrate that an indiscriminate use of pentoxifylline and 2-deoxyadenosine is not beneficial to fertilization in couples with previous IVF failure. Further prospective research may be needed to assess the benefit of pentoxifylline and 2-deoxyadenosine in patients selected by preliminary functional in vitro tests.

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.

Influence of pentoxifylline on human sperm motility in asthenozoospermic individuals using computer-assisted analysis

This study was conducted to evaluate the in vitro effects of pentoxifylline on sperm motility from asthenozoospermic men. The sperm were prepared by a swim-up technique from the unprocessed semen. After centrifugation, sperm were resuspended in the presence or absence (controls) of 3.6 mM pentoxifylline in Earle's solution for up to 180 min. Sperm motility was measured using computer-assisted (Hamilton-Thorn Research) semen analysis. Pentoxifylline significantly increased the numbers of motile (+28-80%) and progressively motile (+54-117%) sperm over the 180 min studied. These changes were accompanied by increases in the progressive velocity (VSL, +11-44%) and curvilinear velocity (VCL, +12-22%) up to 120 min after exposure to the drug. Concomitant changes were observed in the amplitude of lateral head displacement (ALH, +5-17%) up to 60 min and the beat cross frequency (+16-34%) between 60 and 180 min. The results suggest that pentoxifylline consistently enhances both the numbers of motile and progressively motile sperm and the quality of their movement.

Sperm function and its manipulation for microassisted fertilization

Comprehension of the intricate complexities of sperm function is clearly crucial to the success of attempts to manipulate it for the purposes of assisted conception. This is particularly important when considering various procedures for microassisted fertilization since these bypass critical physiological events that are mandatory for normal fertilization, to varying degrees. Methylxanthine derivatives such as pentoxifylline are useful agents for the management of oligoasthenozoospermic patients. This is particularly so for procedures such as SUZI where adequate motility of spermatozoa injected into the perivitelline space is crucial for fusion with the vitelline membrane to achieve fertilization. The generation of minute concentrations of reactive oxygen species in vitro may prove to be a valuable technique in this respect, in the light of recent evidence for their involvement in capacitation and hyperactivation. Induction of the acrosome reaction by non-invasive, non-toxic agents should markedly improve success rates for microassisted fertilization. Acrosin appears to play a central role in this and, therefore, it would seem prudent to monitor levels of acrosin activity in samples of spermatozoa used in assisted conception procedures. With respect to microassisted fertilization, the potential to select recently acrosome-reacted spermatozoa coated by activated acrosin promises to be a major improvement. Current methods employed for determination of the fertilization potential of spermatozoa are clearly inadequate (Polansky and Lamb, 1988; Aitken, 1990). In fact, the prevailing evidence suggests that no single parameter of sperm function reflects this potential (Zaneveld and Jeyendran, 1988). Therefore, we have both a scientific and a moral responsibility to investigate these processes further. Subsequently, we should be in a position to identify individual gametes with the potential for fertilization and so utilize procedures that result in maximal fertilization rates with minimal risk of polyploidy or abnormality.