Hyaluronidase activity in human semen: correlation with fertilization in vitro*†*Supported by Medical Research Council of Canada, Ottawa, Ontario, Canada.†Presented in part at the Canadian Fertility and Andrology Society, St. Andrew’s by the Sea, New Brunswick, Canada, September 7 to 9, 1994

A hyaluronic acid-containing reagent compatible with glass-bottom dishes and capable of sustained binding of human spermatozoa

OBJECTIVE

Commercial products currently available for sperm selection utilizing hyaluronic acid (HA) binding prior to intracytoplasmic sperm injection (ICSI) are widely used but have some disadvantages. To potentially circumvent these limitations, we compared ICSI using a self-made hyaluronic acid (smHA) reagent with ICSI using SpermSlow.

METHODS

The binding of the reagents to spermatozoa on plastic- or glass-bottom dishes was quantitated using spermatozoa that were isolated by density-gradient centrifugation and swim-up procedures (N = 10/group). Additionally, we investigated the relationship between the HA reagent used prior to ICSI and clinical outcomes after assisted reproduction with HA-ICSI (N = 81).

RESULTS

The smHA reagent exhibited extremely stable binding to human spermatozoa. The binding time of spermatozoa was significantly longer in the smHA reagent than in SpermSlow on both plastic and glass dishes (plastic: 60.0 ± 0.0 min vs. 2.7 ± 5.9 min, P < 0.001; glass: 60.0 ± 0.0 min vs. 2.5 ± 1.8 min, P < 0.001). There were no significant differences in the normal fertilization rate between HA-ICSI with the smHA reagent (128/160, 80.0%) and HA-ICSI with SpermSlow (171/231, 74.0%, P = 0.184). The frequency of the blastocyst development from the HA-ICSI-derived zygote was significantly higher with the smHA reagent (74/101, 73.3%) than with SpermSlow (76/131, 58.0%, P = 0.019). The rates of biochemical pregnancy, clinical pregnancy, fetal heart movement, live birth, and miscarriage were not significantly different between HA-ICSI with the smHA reagent and HA-ICSI with SpermSlow.

CONCLUSIONS

The blastulation rate was higher for HA-ICSI with the smHA reagent as compared with SpermSlow. Clinical outcomes, excluding blastulation, after HA-ICSI were the same using smHA reagent and using SpermSlow. Spermatozoa binding to the smHA reagent was not attenuated over a 60-min time course. In conclusion, this reagent may shorten and simplify HA-ICSI procedures because smHA can be used with any dish material, making it easier to observe the spindle or assess intracytoplasmic morphology.

Toxicity of the recombinant human hyaluronidase ALT-BC4 on embryonic development

Cumulus-oocyte complexes (COCs), which contain immature oocytes, are matured in vitro for in vitro embryo production. Oocyte and cumulus cells are then separated using hyaluronidase. To date, there have only been a few reported cases of the toxic effects of hyaluronidase on porcine oocytes. The aim of this study was to compare the effects of bovine testis-derived hyaluronidase and recombinant human hyaluronidase on oocyte denudation and quality. Porcine COCs were matured for 44 h and denuded using different hyaluronidase concentrations and exposure times. Then, oocytes were activated by electrical parthenogenesis. In experiment 1, COCs were denuded using bovine-derived, ovine-derived (Hirax), and human recombinant (ALT-BC4) hyaluronidases for 10 and 20 min. In experiment 2, bovine-derived and human recombinant (ALT-BC4 and ICSI Cumulase^®) hyaluronidases were used to denude the COCs for 2 and 20 min. In both experiments the oocytes were all completely denuded, and there was no degeneration. Rate of embryo development was significantly increased in group treated ALT-BC4 for 2 min and not significantly different in other treatment groups. In general it slightly decreased with longer exposure times. These results have confirmed that different sources of hyaluronidase do not have detrimental effects on the quality of porcine oocytes and suggest that the human recombinant hyaluronidase ALT-BC4 is suitable for oocyte denudation with an increased blastocyst rate.

SPAM1/HYAL5 double deficiency in male mice leads to severe male subfertility caused by a cumulus-oocyte complex penetration defect

The glycosylphosphatidylinositol-anchored sperm hyaluronidases (Hyals), sperm adhesion molecule 1 (SPAM1) and HYAL5, have long been believed to assist in sperm penetration through the cumulus-oocyte complex (COC), but their role in mammalian fertilization remains unclear. Previously, we have shown that mouse sperm devoid of either Spam1 or Hyal5 are still capable of penetrating the COC and that the loss of either Spam1 or Hyal5 alone does not cause male infertility in mice. In the present study, we found that Spam1/Hyal5 double knockout (dKO) mice produced significantly fewer offspring compared with wild-type (WT) mice, and this was due to defective COC dispersal. A comparative analysis between WT and Spam1/Hyal5 dKO epididymal sperm revealed that the absence of these 2 sperm Hyals resulted in a marked accumulation of sperm on the outside of the COC. This impaired sperm activity is likely due to the deficiency in the sperm Hyals, even though other somatic Hyals are expressed normally in the dKO mice. The fertilization ability of the Spam1/Hyal5 dKO sperm was restored by adding purified human sperm Hyal to the in vitro fertilization medium. Our results suggest that Hyal deficiency in sperm may be a significant risk factor for male sterility.-Park, S., Kim, Y.-H., Jeong, P.-S., Park, C., Lee, J.-W., Kim, J.-S., Wee, G., Song, B.-S., Park, B.-J., Kim, S.-H., Sim, B.-W., Kim, S.-U., Triggs-Raine, B., Baba, T., Lee, S.-R., Kim, E. SPAM1/HYAL5 double deficiency in male mice leads to severe male subfertility caused by a cumulus-oocyte complex penetration defect.

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.

FDA-approved drugs that are spermatotoxic in animals and the utility of animal testing for human risk prediction

PURPOSE

This study reviews FDA-approved drugs that negatively impact spermatozoa in animals, as well as how these findings reflect on observations in human male gametes.

METHODS

The FDA drug warning labels included in the DailyMed database and the peer-reviewed literature in the PubMed database were searched for information to identify single-ingredient, FDA-approved prescription drugs with spermatotoxic effects.

RESULTS

A total of 235 unique, single-ingredient, FDA-approved drugs reported to be spermatotoxic in animals were identified in the drug labels. Forty-nine of these had documented negative effects on humans in either the drug label or literature, while 31 had no effect or a positive impact on human sperm. For the other 155 drugs that were spermatotoxic in animals, no human data was available.

CONCLUSION

The current animal models are not very effective for predicting human spermatotoxicity, and there is limited information available about the impact of many drugs on human spermatozoa. New approaches should be designed that more accurately reflect the findings in men, including more studies on human sperm in vitro and studies using other systems (ex vivo tissue culture, xenograft models, in silico studies, etc.). In addition, the present data is often incomplete or reported in a manner that prevents interpretation of their clinical relevance. Changes should be made to the requirements for pre-clinical testing, drug surveillance, and the warning labels of drugs to ensure that the potential risks to human fertility are clearly indicated.

Stimuli-sensitive thiolated hyaluronic acid based nanofibers: synthesis, preclinical safety and in vitro anti-HIV activity

AIM

To develop a seminal enzyme bioresponsive, mucoadhesive nanofibers (NFs) as safe and effective nanocarriers for the prevention of HIV vaginal transmission.

METHODS

A novel thiolated hyaluronic acid (HA-SH) polymer was synthesized to fabricate tenofovir (TFV)-loaded electrospun NFs (HA-SH-NFs) and characterized in vitro/in vivo.

RESULTS

A triggered drug release (87% w/w) from the engineered HA-SH-NFs (mean diameter ∼75 nm) occured within 1 h under the influence of seminal hyaluronidase enzyme. HA-SH-NFs were noncytotoxic, induced no damage on the C57BL/6 mice genital-tract and other organs. No significant CD45 cell-infiltration and changes in cytokines level in cervicovaginal tissues were observed. HA-SH-NFs significantly enhanced both TFV retention and bioavailability in vaginal tissue compared with the 1% TFV-gel. The anti-HIV activity of TFV (on pseudotyped virus followed by luciferase assay) was not adversely affected by the electrospinning process.

CONCLUSION

HA-SH-NFs developed in this study could potentially serve as a safe nanotemplate for topical intravaginal delivery of HIV/AIDS microbicides.

Separation, characterization and identification of boar seminal plasma proteins

Methods used for the isolation, separation and characterization of boar seminal plasma proteins are discussed, as well as techniques applied to study their binding properties. Attention is paid to interactions of these proteins with different types of saccharides and glycoconjugates, with membrane phospholipids, and to interactions between proteins. Boar seminal plasma contains different types of proteins: spermadhesins of the AQN and AWN families; DQH and PSP proteins belong to the most abundant. Some of these proteins are bound to the sperm surface during ejaculation and thus protein-coating layers of sperm are formed. Sperms coated with proteins participate in different types of interactions occurring in the course of the reproduction process, e.g. formation of the oviductal sperm reservoir, sperm capacitation, oocyte recognition and sperm binding to the oocyte.

Effect of varicocelectomy on sperm creatine kinase, HspA2 chaperone protein (creatine kinase-M type), LDH, LDH-X, and lipid peroxidation product levels in infertile men with varicocele

OBJECTIVES

To determine the total sperm creatine kinase, HspA2 chaperone protein (creatine kinase-M isoform), lactate dehydrogenase (LDH), LDH-X activities, and lipid peroxidation product (malondialdehyde [MDA]) levels in infertile men with varicocele and to examine the possible effect of varicocelectomy on these parameters.

METHODS

Eighty-one men were enrolled in this study. The study population consisted of a control group (n = 25) and a varicocele group (n = 56). Of the 56 patients with varicocele, 26 underwent microsurgical subinguinal varicocelectomy at our institution between July 2002 and July 2003. The standard semen parameters (sperm concentration and motility and Kruger morphology) and total sperm creatine kinase, HspA2, LDH, and LDH-X activities, and MDA levels were assessed in the control and varicocele groups. The differences were compared between the two groups. The same parameters were repeated at 6 months postoperatively in the varicocelectomy group and the preoperative and postoperative results were compared.

RESULTS

The sperm concentration was significantly lower in the varicocele group than in the control group (P = 0.01). The mean sperm HspA2 activities were significantly lower and the LDH activities and MDA levels were significantly greater in the varicocele group than in the control group (P = 0.005 and P = 0.001, P < 0.001, respectively). No statistically significant difference was found in the semen parameters in the varicocelectomy group preoperatively and postoperatively. Sperm HspA2 activities increased significantly after varicocelectomy compared with preoperatively (P < 0.001).

CONCLUSIONS

Our data suggest that sperm HspA2 activities are lower and LDH activities and MDA levels are greater in infertile men with varicocele. These data also suggest that varicocelectomy increases HspA2 activities in these patients.

Characterization of Hyaluronidase Isolated from Agkistrodon contortrix contortrix (Southern Copperhead) Venom

Snake venoms are a rich source of enzymes including many hydrolytic enzymes. Some enzymes such as phospholipase A2, proteolytic enzymes, and phosphodiesterases are well characterized. However many enzymes, such as the glycosidase, hyaluronidase, have not been studied extensively. Here we describe the characterization of snake venom hyaluronidase. In order to determine which venom was the best source for isolation of the enzyme, the hyaluronidase activity of 19 venoms from Elapidae, Viperidae, and Crotalidae snakes was determined. Since Agkistrodon contortrix contortrix venom showed the highest activity, this venom was used for purification of hyaluronidase. Molecular weight was determined by matrix-assisted laser desorption ionization mass spectroscopy and was found to be 59,290 Da. The molecular weight value as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was 61,000 Da. Substrate specificity studies indicated that the snake venom enzyme was specific only for hyaluronan and did not hydrolyze similar polysaccharides of chondroitin, chondroitin sulfate A (chondroitin 4-sulfate), chondroitin sulfate B (dermatan sulfate), chondroitin sulfate C (chondroitin 6-sulfate), chondroitin sulfate D, chondroitin sulfate E, or heparin. The enzyme is an endo-glycosidase without exo-glycosidase activity, as it did not hydrolyze p-nitrophenyl-beta-D-glucuronide or p-nitrophenyl-N-acetyl-beta-D-glucosaminide. The main hydrolysis products from hyaluronan were hexa- and tetrasaccharides with N-acetylglucosamine at the reducing terminal. The cleavage point is at the beta1,4-glycosidic linkage and not at the beta1,3-glycosidic linkage. Thus, snake venom hyaluronidase is an endo-beta-N-acetylhexosaminidase specific for hyaluronan.