The role of potassium ion and extracellular alkalization in reinitiation of human spermatozoa preserved in electrolyte-free solution at 4 degrees C

Human sperm parameter improvement associated with Ceratonia siliqua extract as a cryopreservation supplement after vitrification

OBJECTIVE

Given the destructive effects of oxidative stress on sperm structure, this study was conducted to investigate the antioxidant effects of different concentrations of Ceratonia siliqua plant extract on human sperm parameters after the freezing-thawing process.

METHODS

A total of 20 normozoospermic samples were frozen. Each sample was divided into two control groups (fresh and cryopreservation) and three cryopreservation experimental groups (containing C. siliqua extract at concentrations of 20, 30, and 40 μg/mL in the freezing extender). Motility, intracellular levels of reactive oxygen species (ROS), plasma membrane integrity (PMI), mitochondrial membrane potential (MMP), viability, and acrosome reaction parameters were evaluated.

RESULTS

Statistical analysis showed that the highest motility, viability, and PMI were associated with the 20 μg/mL concentration of C. siliqua extract. At all concentrations, intracellular ROS levels were significantly lower and the levels of MMP and the acrosome reaction were significantly higher than in the cryopreservation control group (p≤0.05).

CONCLUSION

C. siliqua extract supplements at concentrations of 20, 30, and 40 μg/mL improved sperm motility, viability, PMI, MMP, intracellular ROS, and the acrosome reaction.

Extend the Survival of Human Sperm In Vitro in Non-Freezing Conditions: Damage Mechanisms, Preservation Technologies, and Clinical Applications

Preservation of human spermatozoa in vitro at normothermia or hypothermia maintaining their functions and fertility for several days plays a significant role in reproductive biology and medicine. However, it is well known that human spermatozoa left in vitro deteriorate over time irreversibly as the consequence of various stresses such as the change of osmolarity, energy deficiency, and oxidative damage, leading to substantial limitations including the need for semen examinations, fertility preservation, and assisted reproductive technology. These problems may be addressed with the aid of non-freezing storage techniques. The main and most effective preservation strategies are the partial or total replacement of seminal plasma with culture medium, named as extenders, and temperature-induced metabolic restriction. Semen extenders consist of buffers, osmolytes, and antioxidants, etc. to protect spermatozoa against the above-mentioned adverse factors. Extended preservation of human spermatozoa in vitro has a negative effect on sperm parameters, whereas its effect on ART outcomes remains inconsistent. The storage duration, temperature, and pre-treatment of semen should be determined according to the aims of preservation. Advanced techniques such as nanotechnology and omics have been introduced and show great potential in the lifespan extension of human sperm. It is certain that more patients will benefit from it in the near future. This review provided an overview of the current knowledge and prospects of prolonged non-freezing storage of human sperm in vitro.

Improvement of the motility of boar sperm after cryopreservation

After the sperm cryopreservation process, there frequently is a marked decrease in sperm motility, however, this loss of motility could be avoided or reduced by modifying the thawing extender. The aim of conducting this study was to evaluate treatments resulting in differences in pH of the thawing extender on post-thawing sperm quality, especially motility. The associated effects were evaluated of the thawing extender pH when there were pH values of 7, 8 and 9 on values for sperm viability, acrosome integrity, motility and kinematic variables. To evaluate pH effects of the thawing extender on sperm motility, the procedures for evaluating the sperm variables were conducted with or without inclusion of caffeine in the extender. In addition, effects of thawing extender pH on the sperm subpopulations were analyzed. The results indicated that by increasing the pH of thawing extender to 9, sperm viability and acrosome status were not affected, and motility was markedly greater with there being similar values when there was a pH of greater alkalinity and pH 7 when caffeine was included for conducting the evaluations. Furthermore, for values of kinematic variables and sperm subpopulations, when there was a pH of 8 of thawing extender, sperm motility was maintained to a greater extent as storage duration advanced and the proportions of different sperm populations were also maintained during storage. In conclusion, when there was use of the thawing extender at pH 8, there was enhanced post-thawing sperm motility and preservation of motility as storage time advanced.

Viability longevity and quality of epididymal sperm stored in the liquid state of European red deer (Cervus elaphus elaphus)

The aim of the study was to evaluate viability longevity and quality of liquid-stored epididymal sperm of European red deer (Cervus elaphus elaphus). Sperm samples were recovered from epididymides of 15 mature stags. Samples were diluted to 100 × 10⁶ sperm⁄mL in modified Salomon's extender and stored at 5 °C for 25 days. Sperm were analyzed to determine total motility (TMOT), progressive motility (PMOT) and motion variables [CASA system], acrosomes with normal apical ridges (NAR), viability and acrosomal status (FITC-PNA/PI), plasma membrane integrity (PMI) and mitochondrial membrane potential (MMP) on the first day (D1) and every other day of storage (D3-D25). Data were analyzed using a one-way analysis of variance (ANOVA). Spermatozoa remained motile until D25, whereas TMOT exceeded 60%, NAR and PMI exceeded 80%, FITC-PNA/PI exceeded 75%, and MMP approximated 70% until D11. There was a lesser (P < 0.05) value for these variables on D5 (relative to D1). Furthermore, there was a decrease in values for motility variables as duration of storage increased, excluding amplitude of lateral head displacement, on D3. The results indicate that liquid-stored epididymal sperm of European red deer are characterized as having a long viability (25 days) with a retention of sperm quality for as long as 11 days in the liquid storage state. In vitro or in vivo studies, however, are required to confirm the findings in the present study.

Functional studies of acid transporter in cultured rat epididymal cell

OBJECTIVE

To explore the functional role of vacuolar H(+)-ATPase in the pH regulation of epididymal fluid and its effect on sperm motility.

DESIGN

Experimental study.

SETTING

Physiology laboratory in a university.

ANIMAL(S)

Immature male Sprague-Dawley rats.

INTERVENTION(S)

The H(+)-ATPase inhibitor was applied to the primary culture of epididymal cells.

MAIN OUTCOME MEASURE(S)

The intracellular luminal fluid pH and sperm percent motility were recorded.

RESULT(S)

Double immunofluorescence of H(+)-ATPase and carbonic anhydrase II in primary culture of cauda epididymal epithelial cells showed that the system was a suitable model for investigation of acid secretion by clear cells. Clear cells were pharmacologically distinct from principal cells in acid/base transportation. The intracellular pH recovery from cellular acidification was suppressed by the H(+)-ATPase inhibitor bafilomycin A1(100 nM) and the Na(+)/H(+) exchanger inhibitor amiloride (1 mM) by 85% and 54%, respectively. These results suggest that, in addition to Na(+)/H(+) exchanger, clear cells actively pump proton from cytoplasm into extracellular space through H(+)-ATPase. In addition, inhibition of H(+)-ATPase by bafilomycin A1 blocked the acidification of luminal fluid with IC(50) values of 12 nM, which supports that H(+)-ATPase acidifies the luminal fluid. We also confirm that the acid fluid regulates rat cauda sperm motility.

CONCLUSION(S)

The present work shows that clear cells, the minority cell type of epididymal cell population, play an important role in the pH regulation of epididymal fluid by H(+)-ATPase.

Effects of arachnotoxin on intracellular pH and calcium in human spermatozoa

OBJECTIVE

To determine the effect of arachnotoxin (ATx), a venom extracted from the Chilean spider Latrodectus mactans, on intracellular calcium ([Ca(2+)](i)) and pH (pH(i)) in capacitated human spermatozoa.

DESIGN

Spermatozoa were collected from fertile adult men (n = 8). Mobile spermatozoa were collected by the "swim up" technique and stimulated with the crude extract of ATx and with progesterone (P).

SETTING

Hospital of the Federal University of São Paulo, São Paulo, Brazil.

MAIN OUTCOME MEASURE(S)

[Ca(2+)](i) was measured in fura2-AM-loaded spermatozoa, and pH(i) was measured in spermatozoa loaded with the pH-sensitive dye [(2',7')-bis (carboxymethyl)-(5,6)-carboxyfluorescein]-AM (BCECF).

RESULT(S)

The ATx and P induced a biphasic change in [Ca(2+)](i) consisting of a peak followed by a small but sustained elevation. The response to ATx was greatly reduced by pretreatment with P. The ATx caused intracellular acidification, whereas P induced alkalinization. Blockade of the NA(+)/H(+) exchanger with ethylisopropylamiloride (EIPA) sharply increased ATx-induced acidification.

CONCLUSION(S)

Arachnotoxin increased [Ca(2+)](i) through the opening of calcium channels and release of calcium from intracellular stores. The ATx reduced pH(i) in human sperm, possibly by inhibiting the Na(+)/H(+) exchanger.

Influence of glucose and fructose in the extender during long-term storage of chilled canine semen

The use of chilled, extended semen in dog breeding is becoming increasingly popular as preparation and transportation is less expensive and regulations are often less complicated than for frozen semen. Sugar is one of the main constituents in semen extenders, and glucose and fructose are metabolized in separate pathways by freshly ejaculated dog sperm. In this study, glucose, fructose or an equal mixture of both were used in an egg-yolk-tris (EYT) extender at two different concentrations (10 and 70 mM). EYT extender without sugar supplementation, providing only the glucose (3-4 mM) originating from the egg-yolk, served as a control. The longevity of the chilled semen at 5 degrees C was 23 days: the quality of physical and functional characteristics decreasing with time. Glucose and fructose had a strong influence on motility and movement patterns of chilled canine semen. The beneficial effect of 70 mM sugar concentrations compared to 10 mM and the control was pronounced, and maintained sperm motility > or = 70% for 8 days of storage, compared to for 4 days in the control extender. Fructose maintained higher sperm motility than did glucose and the mixture. VAP values were higher in sugar-supplemented extenders (P < 0.05). Neither type nor concentration of the two sugars influenced sperm plasma membrane, acrosome integrity or the acrosome reaction following ionophore challenge (ARIC). Sugar consumption by dog sperm varied between the different periods of storage and with sugar concentrations provided in the extenders. Glucose consumption by dog sperm was greater than fructose consumption when both sugars were present in equal amounts, indicating that dog sperm used glucose in preference to fructose. In conclusion, the major influence of the two sugars on chilled semen was to support motility. EYT extender supplemented with fructose at a concentration of 70 mM was found to be the best of the tested extenders for long-term preservation of chilled canine semen.

Effect of cooling on the motility and function of human spermatozoa

Human spermatozoa were cooled from 37 to 0 degrees C at 10 degrees C min(-1) in 5 degrees C steps with 1 min equilibration at each step, the temperature control was +/- 0.1 degrees C. Spermatozoa were held at 0 degrees C for 5 min and then rewarmed at the same rate. No significant effect of cooling on the straight-line velocity was found using computer-aided semen analysis. The physiological function of spermatozoa was also examined before and after cooling using hypoosmotic swelling, ionophore-provoked acrosome reaction, and binding to fragments of human zonae pellucidae. Spermatozoa were cooled either in seminal plasma or in conventional IVF medium with or without fractionation by centrifugation through a discontinuous Percoll gradient. When spermatozoa were cooled and rewarmed in seminal plasma there was no significant change in either the ionophore-induced acrosome reaction or the binding to zona pellucida fragments. When spermatozoa were fractionated by centrifugation through Percoll an increased response in both was seen. However, following cooling and rewarming, a significant decline in the response of both occurred. We suggest that motility alone is not a reliable predictor of changes in other physiological functions of spermatozoa following cooling. Furthermore, short-term cooling appears to have no significant detrimental effect on normozoospermic samples and cold shock may be avoided in the clinical context by controlled cooling and warming.

Effects of preservation of mouse spermatozoa in electrolyte-free solution at 4 degrees C on the outcome of mouse in vitro fertilization

PURPOSE

The aim was to assess the fertilizing capacity of spermatozoa cool-preserved in electrolyte-free (EF) solution.

METHODS

Mouse spermatozoa were cool-preserved in EF solution and the acrosomal status of the spermatozoa was compared before and after preservation using chlortetracycline stain. Mouse oocytes were inseminated by spermatozoa cool-preserved in EF solution for 2, 4, or 7 days and fertilization and blastocyst rates were evaluated.

RESULTS

Acrosomal status of spermatozoa cool-preserved in EF solution was not different from spermatozoa before preservation, but the capacitated and acrosome-reacted spermatozoa significantly increased after reinitiation. Cool-preservation in EF solution for up to 4 days did not affect fertilization rate. Blastocyst rate of embryos derived from spermatozoa cool-preserved for 4 or 7 days in EF solution was significantly lower than that of embryos derived from fresh spermatozoa.

CONCLUSIONS

Mouse spermatozoa cool-preserved in EF solution possesses as much fertilizing capacity as fresh spermatozoa. However, prolonged preservation affects the embryonic development.

Effects of extracellular ions on the reactivation of human spermatozoa preserved in electrolyte-free solution

It has previously been reported that human spermatozoa preserved in an electrolyte-free solution can survive for several weeks at 4 degrees C. However, the motility of spermatozoa after preservation cannot be restored when incubated at 37 degrees C, unless reactivated by extracellular alkalisation. Under weak acidic conditions, the reactivation is induced by > or = 10 mmol l-1 Na+ and inhibited by a Na(+)-H+ antiporter inhibitor. The addition of > or = 0.1 mmol l-1 K+ also induces the reactivation. In the present study, the reactivation was induced by > or = 0.1 mmol l-1 Rb+ or > or = 1 mmol l-1 Cs+ at an acidic pH. The maximum motility rate with K+, Rb+ or Cs+ was obtained at 10-20 mmol l-1 and inhibited by 10(-5)-10(-2) mol l-1 ouabain in a dose-dependent manner, while ouabain had no effect on the Na(+)-induced reactivation. The addition of K+ further increased sperm motility reactivated by Na+, which was also inhibited by ouabain. The addition of Ca2+ did not induce the reactivation or increase sperm motility reactivated by Na+ or K+. It was concluded that activation of the ouabain-sensitive Na(+)-K(+)-ATPase and Na(+)-H+ exchange mechanism has an important role in sperm motility.

The effect of pH on the motility of spermatozoa from chicken, turkey and quail

At 40 degrees C in a NaCl-based buffer the motility of spermatoza from chicken, turkey and quail was inhibited at pH values below 7.8, 7.2 and 7.2, respectively. At these pH values the percentage motile and velocity of spermatoza were relatively low, but the motility became vigorous when the pH was raised by 0.2 units and increased even more following further alkalinization. Spermatozoa from all three species stored motionless at pH 6.0 for 3 h could be reactivated by dilution in an alkaline solution (pH 9.0). These findings support the hypothesis that a change in the environmental pH could be implicated in the suppression and stimulation of sperm motility during oviducal sperm storage and transport.

Successful pregnancy with sperm retrieved from the bladder after the introduction of a low-electrolyte solution for retrograde ejaculation

OBJECTIVE

To determine the safety and efficacy of the introduction of a low-electrolyte solution into the bladder before masturbation for sperm recovery in patients with retrograde ejaculation.

DESIGN

Two case reports.

SETTING

Assisted reproduction practice at a university hospital.

PATIENT(S)

Two men with retrograde ejaculation.

INTERVENTION(S)

A 0.32-mol/L glucose solution or Ham's modified F-10 medium (GIBCO, Grand Island, NY) with 10% serum was introduced into the urinary bladder before masturbation. The retrieved sperm were used for IUI.

MAIN OUTCOME MEASURE(S)

The motility of retrieved sperm, achievement of pregnancy, and outcome of pregnancy.

RESULT(S)

In patient 1, the motility rate of sperm retrieved from the bladder after the introduction of Ham's modified F-10 medium was higher than that after the introduction of a glucose solution. The patient's wife did not become pregnant during 10 IUI cycles after treatment with Ham's modified F-10 medium. However, she became pregnant during the first IUI cycle after treatment with a glucose solution and was delivered of healthy twin infants. The wife of patient 2 also became pregnant during the first IUI cycle after treatment with a glucose solution and was delivered of a healthy female infant.

CONCLUSION(S)

The introduction of a glucose solution appears to be a safe and simple method for sperm recovery in patients with retrograde ejaculation.

Viability and function of human sperm in electrolyte-free cold preservation

OBJECTIVE

To assess the viability and function of human sperm in electrolyte-free cold preservation.

DESIGN

Prospective comparative study.

SETTING

Andrology laboratory of our hospital.

PATIENT(S)

Ten semen samples obtained from patients attending our infertility clinic.

INTERVENTION(S)

Ejaculated sperm were washed using the electrolyte-free Percoll gradient and were then preserved in 0.33 M glucose solution, 0.16 M NaCl solution, 0.16 M KCl solution at 4 degrees C for 4 weeks. As a control, TEST (TES and Tris) yolk buffer (TYB) was added to the ejaculated semen and preserved at 4 degrees C.

MAIN OUTCOME MEASURE(S)

Sperm tail morphology, motility, viability (eosin-Y stain), and the concentration of adenosine triphosphate (ATP) were analyzed.

RESULT(S)

The number of sperm with normal tail form and the motility of sperm preserved in glucose solution (electrolyte-free cold preservation) were significantly (P < 0.01) higher for 4 weeks than those of sperm preserved in the other three media. The sperm viability in glucose solution was 75.5%, 65.4%, and 51.3%, after 1, 2, and 4 weeks, respectively. The ATP concentration after 1, 2, and 4 weeks remained 64.2%, 53.0%, and 4.3% of the prestorage value, respectively, in the sperm stored in glucose solution.

CONCLUSION(S)

The morphology, motility, viability, and ATP concentration of sperm in electrolyte-free cold preservation were substantially better than those in NaCl solution, KCl solution, or TYB for 2 weeks.