Micro-quantity straw as a carrier for cryopreservation of oligozoospermic semen samples: Effects of storage times and cryoprotectant

Application of an appropriate freezing carrier is crucial for improving post-thaw recovery of oligozoospermic samples. In this study, our purpose is developing a user-friendly, easy handling and close micro-quantity (MQ) straw along with different freezing media, for cryopreservation of oligozoospermic samples. Twenty oligozoospermic semen samples were collected and mixed with glycerol egg yolk citrate (GEYC) or Spermfreeze^® (SPF) medium. The mixture was loaded into MQ straws, sealed and stored in liquid nitrogen (LN) vapor. After freezing, the straws were transferred into cryotube and plunged into LN. Post-thawed sperm parameters including motion characteristics, viability, membrane and DNA integrity were evaluated one and three months after cryopreservation. The post-thawed sperm parameters were significantly reduced in GEYC and SPF medium compared to fresh samples. No statistically significant differences were seen in sperm characteristics between the two storage times (i.e. month 1 vs. month 3). Furthermore, GEYC medium yielded higher motility, viability and membrane integrity compared to SPF at both storage time-points. Sperm DNA integrity was also improved in GEYC group compared to SPF after 1 month of storage. The findings of our study showed that application of MQ straw along with GEYC, as the cryoprotectant, was beneficial for cryopreservation of low count semen samples.     

Mitochondria-targeted antioxidant MitoTEMPO improves the post-thaw sperm quality

Human spermatozoa cryopreservation is an important means of assisted reproductive technology and male fertility preservation. Although this technique is particularly useful, sperm cryopreservation significantly reduces the quality of spermatozoa after freezing and thawing. The objective of the study is to examine the efficacy of mitochondria-targeted antioxidant MitoTEMPO in improving sperm quality during semen cryopreservation processes. Semen samples were collected and cryopreserved in extenders containing different concentrations (0.0, 0.5, 5, 50, and 500 μM) of MitoTEMPO. Sperm motility, viability, membrane integrity, mitochondrial membrane potential and antioxidant activities were measured and analyzed. The results showed that the addition of MitoTEMPO (5–50 μM) significantly improved post-thaw sperm motility, viability, membrane integrity and mitochondrial membrane potential (P < .05). Meanwhile, antioxidant enzymes activities were enhanced and MDA content were decreased in the group supplemented with MitoTEMPO. In conclusion, mitochondria-targeted antioxidant MitoTEMPO improves the post-thaw sperm quality and antioxidant enzymes profile.     

Mito-Tempo alleviates cryodamage by regulating intracellular oxidative metabolism in spermatozoa from asthenozoospermic patients

As the largest proportion of male infertility population, asthenozoospermia patients often resort to sperm cryopreservation to preserve fertility as well as to enrich motile sperm for assisted reproductive techniques (ART), although it may cause some cryodamage during the freezing–thawing process. The objective of this study was to investigate whether mitochondrial antioxidant Mito-Tempo was effective in preventing cryodamage of asthenozoospermic spermatozoa. Asthenozoospermic semen samples were collected and cryopreserved in media supplemented with different concentrations (0.0, 1.0, 10 and 100 μM) of Mito-Tempo. We measured sperm motility, viability, membrane integrity, DNA fragmentation, mitochondrial membrane potential, oxidation product, and antioxidant enzymes activities. Supplementation of the cryopreservation media with Mito-Tempo (10 and 100 μM) induced a significant improvement in sperm viability, motility, membrane integrity, mitochondrial membrane potential and chromatin integrity (P < 0.05). Significant enhancement of antioxidant enzymes activities accompanied by the decreased formation of oxidation products (ROS and MDA) was also observed in groups supplemented with Mito-Tempo (10 and 100 μM). It is concluded that mitochondria targeted antioxidant Mito-Tempo alleviates cryodamage by regulating intracellular oxidative metabolism in spermatozoa from asthenozoospermic patients after cryopreservation.     

The relationship between sperm DNA fragmentation,free radicals and antioxidant capacity with idiopathic repeated pregnancy loss

More than two consecutive miscarriages in less than 20 weeks of gestation is defined as recurrent spontaneous miscarriage. Various causes such as uterine anatomical anomalies, genetic factors, and infectious and endocrine disorders have been reported for RPL. However, approximately 50% of the causes are unknown, which can be due to male factors. Several studies have been done on semen parameters to determine the unknown causes and risk factors for miscarriages, however, only studying common semen parameters have not been sufficient. In this study, the relationship between sperm DNA fragmentation, the amount of free radicals, and total antioxidant capacity (TAC) in semen have been considered as a risk factor for spontaneous miscarriage. Semen samples were collected from 42 men whose partners had a history of spontaneous miscarriage and 42 fertile men as the control group. Volume, pH, viscosity, concentration, and motility of semen, as well as sperm morphology were measured. Sperm DNA fragmentation was analyzed by the sperm chromatin structure assay (SCSA) and TUNEL methods, the amount of sperm free radicals was measured by the luminescence method and the total amount of semen antioxidant was measured using the TAC kit. The results have shown that sperm motility in the experimental group was significantly less than the control group (P?=?0.001). The percentage of sperm DNA fragmentation and the amount of free radicals in the experimental group were significantly higher than the control group (P?<?0.001). The total amount of antioxidant was lower in the experimental group compared to the control. Spouses of men with lower sperm motility and higher DNA fragmentation had a higher chance of spontaneous miscarriage when compared to the control group. The results of this study support the hypothesis that sperm DNA fragmentation is a major contributor to spontaneous miscarriage.The relationship between SDF, ROS and TAC with RPL.     

Freeze–thaw induced genotoxicity in buffalo (<Emphasis Type="Italic">Bubalus bubalis</Emphasis>) spermatozoa in relation to total antioxidant status

Use of cryopreserved semen has become an important tool in assisted reproduction but freezing and thawing cause sub-lethal damage to spermatozoa. This is detrimental to sperm because of the membrane damage including permeability and integrity. An excess generation of reactive oxygen species (ROS) creates oxidative stress due to reduced antioxidant status of the cryopreserved spermatozoa. In the present study fresh buffalo semen was collected and divided into two aliquots. One aliquot was used for fresh semen analysis and the other was cryopreserved in Tris-egg yolk-citrate extender. The semen samples were used to study different sperm quality parameters like motility, viability, membrane integrity and total antioxidant status. The DNA integrity in fresh and cryopreserved spermatozoa was also studied using comet assay. The sperm quality parameters like post-thaw sperm motility, viability, membrane integrity and total antioxidant status of cryopreserved spermatozoa were significantly lowered (P < 0.05) compared to fresh spermatozoa. The DNA fragmentation in cryopreserved spermatozoa was significantly higher (P < 0.01) as compared to fresh spermatozoa. The results show that the irreversible DNA damage occurs in spermatozoa during cryopreservation.     

The effect of cryopreservation on sperm head morphometry in Florida male goat related to sperm freezability

The Sperm Class Analyzer was used to investigate the effect of freeze-thawing procedure on Florida buck sperm head morphometry, and to relate possible changes in sperm head dimensions to cryopreservation success. Semen samples (n=76) were frozen with tris and milk-based extenders and thawed. Sperm quality samples (motility, morphology, acrosome), and sperm head morphometric values (length, width, area, perimeter, ellipticity) were compared between fresh and frozen-thawed samples. Sperm freezability was judged according to the sperm quality parameters assessed. Fertility data was obtained after artificial insemination with cryopreserved semen. Cryopreservation success was different between freezing methods. Sperm head dimensions were significantly (p<0.05) smaller in cryopreserved tris and milk spermatozoa respectively than in those of the fresh samples. The sperm head morphometric parameters that had changed after cryopreservation were lower in suitable semen samples after thawing and with successful pregnancies after artificial insemination. These data suggest that changes in sperm head morphometry might reflect spermatozoa injury occurred during cryopreservation.     

Effect of cryopreservant combinations on the motility and morphology of curimba (Prochilodus lineatus) sperm

This study investigated the application of intra- and extra-cellular cryoprotectant combinations on the quality of curimba Prochilodus lineatus semen subjected to cryopreservation. Semen treatments were tested with 8% DMSO or methanol as intracellular cryoprotectant, 5% egg yolk or lactose as extracellular cryoprotectant and 5% BTS. These cryoprotectant combinations are suitable for curimba but have not been tested at the lesser concentrations proposed or in combination with BTS. Semen samples collected from 19 curimbas were diluted into one of four cryoprotectant combinations: DMSO+yolk; DMSO+lactose; methanol+yolk; and methanol+lactose. After dilution, semen samples were cryopreserved in 0.5 mL straws for 10 days in a liquid nitrogen tank. Semen was thawed in a water bath at 60°C for 8s. We evaluated the quality of fresh, diluted (pre-freezing) and post-freezing semen according to sperm motility rate (%) and duration (s). Sperm morphology was also analyzed in thawed semen. Sperm motility rate decreased progressively after dilution and thawing. The motility rate in post-freezing semen was higher in the treatments using DMSO+lactose and methanol+yolk. Sperm motility duration in post-freezing sperm was greater in the treatments using methanol rather than DMSO as intracellular cryoprotectant, irrespective of the extracellular cryoprotectant used. Abnormality frequency in thawed sperm was less in semen treated with egg yolk than with lactose. Thus the use of methanol intracellular cryoprotectant is recommended along with yolk extracellular cryoprotectant in the cryopreservation process for curimba semen.     

Cooling rate affects rhesus monkey sperm survival

Background The rate at which lethal intracellular ice formation occurs during cryopreservation is highly dependent on several variables. The objective of this study was to determine the optimal rate at which rhesus sperm can be cooled. Methods Experiments were performed using three rates of cooling. Sperm motility was evaluated by computer‐assisted semen analysis, and post‐thaw viability was determined using propidium iodide labeling and flow cytometry. Semen was frozen at three cooling rates: (i) fast, (ii) slow, and (iii) standard. Straws were thawed for 30 s at 37°C for analysis of motility and viability. Results Post‐thaw motility and viability were comparable between freezing curves. Sperm cryopreserved using the slow freeze curve exhibited lowest motility and viability. Conclusions This study indicates that macaque sperm survive cooling optimally when cooling rates range from ?17 to ?34°C/minute. Conversely, slow cooling was detrimental and resulted in poor quality sperm.     

The influence of certain aminoacids and vitamins on post-thaw fish sperm motility, viability and DNA fragmentation

During cryopreservation, dilution in the extender media reduces the seminal plasma constituents being cells more vulnerable to oxidative stress. Vitamins (C and E) and the amino acids taurine and hypotaurine are powerful antioxidants naturally present in seminal plasma. Whether their effect may improve sperm quality and reduce sperm DNA damage after cryopreservation in fish sperm still remains unclear. Thus, the aim of the present work was to analyse the effect of extender supplementation with several antioxidant components on post-thawed sperm motility, viability and DNA integrity of two commercial species, gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax). Sperm collected from ten to twelve individuals was cryopreserved in ten different extenders containing: taurine and hypotaurine (1 and 10mM), ascorbic acid (1 and 10mM), α-tocoferol (0.1 and 0.5 mM) or 1 ml/l of a commercial cell antioxidant supplement. Cell viability, motility and DNA fragmentation were determined in post-thawed samples. Addition of antioxidants (vitamins and amino acids) to D. labrax and S. aurata extenders did not significantly increase the parameters of motility (TM, PM, VCL, VSL and Lin) or viability, although 1mM taurine slightly increased the percentage of motile cells (TM) in S. aurata. DNA fragmentation (DNA in tail and Olive tail moment) in D. labrax sperm was higher in treatments containing vitamins than amino acids or control. However in S. aurata sperm, antioxidants especially taurine and hypotaurine, significantly reduced both DNA fragmentation parameters, protecting DNA against strand breaks. These results suggest a species-specific effect depending on the type of antioxidants used.     

Effect of relaxin on cryopreserved beef bull semen characteristics

This study aimed to improve the quality of cryopreserved beef bull (Piedmontese) semen by incorporation of relaxin in diluted semen before cryopreservation procedures. Semen samples were collected from 4 proven fertile bulls, using artificial vagina, once per week for 8 consecutive weeks and pooled together then diluted with Bullxcell® extender, and supplemented with different concentrations of relaxin (0 (control), 25, 50 and 100 ng/ml) before cooling, equilibration and freezing procedures. Frozen semen was thawed and assessed for motility by Computer-Assisted Sperm Analysis and vitality parameters such as acrosome, plasma membrane and DNA integrities, apoptosis, mitochondrial membrane potential, mucus penetration and SOD activity. The developmental potential of bovine embryos produced in vitro by using relaxin-treated was also investigated. In the present study, 50 and 100 ng/ml relaxin incorporation in extended bull semen before cryopreservation induced a reduction of sperm motility immediately after thawing (0h), whereas, during long incubation periods (1–2 h), relaxin showed a significant positive effect on sperm quality by improving the sperm motility and velocity parameters. Interestingly, sperm vitality was improved by 25 and 100 ng/ml relaxin and the blastocyst developmental rate was significantly increased in the 25 ng/ml relaxin group compared with controls (52/118, 44.0% vs. 32/116, 27.6%, respectively). These findings suggest a potential use of relaxin at the doses tested in the present study as an additive in the cryopreservation media of bull semen to improve sperm quality.     

Effect of glycerol addition time on the cryopreserved Korean native brindle cattle (Chikso) sperm quality

Although cryopreservation is an efficient method for maintaining the biological and genetic resources of sperm, the sperm damage during the cryopreservation process cannot be ignored. It should be possible to obtain the most effective cryopreservation performance by accurately grasping the effects of various factors on the cryopreservation of sperm. The previous study demonstrated that a suitable standard protocol for cryopreservation of Korean native brindled cattle (Chikso) does not exist, based on the methods for semen cryopreservation of Chikso differ in each research center. The most obvious difference between most of protocols is the addition of glycerol before and after cooling during the Chikso cryopreserved semen process. Therefore we focused on the effects of glycerol addition time on the quality of cryopreserved Chikso sperm. In the present study, 27 individual Chikso samples were collected by transrectal massage and divided into two parts: the “cryopreservation method A” group (adding glycerol before cooling) and the “cryopreservation method B” group (adding glycerol after cooling). Meanwhile, the values of various sperm parameters were derived from each group, including sperm motility, kinematics, capacitation status, cell viability, and intracellular ATP levels, which we used to compare and evaluate sperm function. The results of this study indicated that during the semen cryopreservation process of the Chikso, the addition of glycerol after cooling yielded superior results in a variety of sperm parameters, such as sperm motility, progressive motility, rapid motility, VCL, VSL, VAP, ALH, capacitation status, viability, and intracellular ATP level after freezing and thawing. Our study is suggested that the glycerol addition time during the cryopreservation process for Chikso should be considered. In addition, our results may be provided reference to develop suitable the cryopreservation procedure of the Chikso sperm.     

Effect of freezing–thawing process and quercetin on human sperm survival and DNA integrity

We aimed in the first part of our work to study the effect of cryopreservation on the human sperm DNA integrity and the activation of caspase 3, the main apoptosis indicator. In the second part, we were interested in testing the effect of quercetin, as an antioxidant, in preventing sperm damage during the freeze–thawing process. Seventeen semen samples were obtained from 17 men recruited for infertility investigations. Liquefied sperm was cryopreserved using spermfreeze®. Nine of the used samples were divided into two aliquots; the first one was cryopreserved with spermfreeze only (control) and the second one was cryopreserved with spermfreeze supplemented with quercetin to a final concentration of 50 μM. Sperm motility and viability were assessed according to WHO criteria. We used TUNEL assay and the Oxy DNA assay to assess sperm DNA integrity. Activated caspase 3 levels were measured in spermatozoa using fluorescein-labeled inhibitor of caspase (FLICA). Cryopreservation led to a significant increase in sperm DNA fragmentation, DNA oxidation and caspase 3 activation (p < 0.01). Supplementation of the cryopreservation medium with quercetrin induced a significant improvement in post thaw sperm parameters, compared to those of control, regarding sperm motility (p = 0.007), viability (p = 0.008) and DNA integrity (p = 0.02); however, it had no effect on caspase 3 activation (p = 0.3). We conclude that oxidative stress plays a major role in inducing sperm cryodamage but implication of apoptosis in this impairment requires further investigations. Quercetin could have protective effect during cryopreservation but further research is needed to confirm this effect.     

Changes in rat spermatozoa function after cooling,cryopreservation and centrifugation processes

Rat sperm cryopreservation is an effective method of archiving valuable strains for biomedical research and handling of rat spermatozoa is very important for successful cryopreservation. The aim of this study was to evaluate changes in rat sperm function during cryopreservation and centrifugation. Epididymal rat spermatozoa were subjected to cooling and freezing–thawing processes and then motility, plasma membrane integrity (PMI), mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were compared before and after minimum centrifugation force (200×g). Cryopreservation decreased sperm motility, PMI, and MMP (P < 0.05). Basal (without ROS inducer, tert-butyl hydroperoxide [TBHP] treatment) and stimulated ROS (with TBHP treatment) were increased in viable cooled spermatozoa compared to viable fresh spermatozoa (P < 0.01), with equal susceptibility to TBHP among fresh, cooled, and frozen–thawed spermatozoa. Centrifugation decreased motility and PMI of frozen–thawed spermatozoa (P < 0.05). Centrifugation decreased basal ROS of all spermatozoa (P < 0.01), while it led to higher susceptibility to TBHP in viable cooled spermatozoa, showing higher increased fold in ROS and decreased rate in viability by TBHP in viable cooled spermatozoa (P < 0.05). Cooling process was the major step of ROS generation, with loss in sperm motility, PMI, and MMP. Centrifugation affected function of cryopreserved spermatozoa. These data suggest that centrifugation makes rat spermatozoa susceptible to external ROS source, in particular during cooling process. Thus, protection from ROS damage and minimizing centrifugation should be considered during cryopreservation and post-thaw use of cryopreserved epididymal rat spermatozoa.     

Improved Human Sperm Recovery Using Superoxide Dismutase and Catalase Supplementation in Semen Cryopreservation Procedure

The aim of this work was to evaluate the effects of ROS scavenger supplementation in human semen samples undergoing cryopreservation procedures.After screening out andrological pathologies, we selected 25 male partners of infertile couples with the following semen profile: volume >/= 2.0 ml, normal viscosity, sperm count >/=20 x 10(6)/ml, straight progressive motility (classes 1 and 2) >/= 40% (Mazzilli, Rossi, Delfino and Nofroni (1999) Andrologia 31: 187-194), atypical forms 相似文献   

Improvement of post-thaw sperm survivals using liquid nitrogen vapor in a spermcasting oyster Ostrea angasi

Low survival of cryopreserved sperm impedes the application of cryopreservation technique in spermcasting oyster species. This study developed a simple method of liquid nitrogen vapor freezing to improve post-thaw sperm survival in the spermcasting oyster Ostrea angasi. The results indicate that the permeable cryoprotectants, dimethyl sulfoxide (DMSO), ethylene glycol (EG) and propylene glycol (PG) were non-toxic to sperm up to 20% concentration and 90 min exposure whereas methanol at 10% or higher was toxic to sperm for any exposure over 30 min. Among the treatments with permeable cryoprotectants, 15% EG produced the highest post-thaw sperm motility. Sperm motility was further improved by the addition of non-permeable cryoprotectants (trehalose and glucose), with 15% EG + 0.2 M trehalose resulting in the highest post-thaw sperm motility among all the combinations evaluated. The durations of 20, 30 and 60 min equilibrations produced a higher post-thaw sperm motility and plasma membrane integrity (PMI) than 10 min. Higher post-thaw motility and PMI were achieved by freezing sperm at the 8 cm height from the liquid nitrogen surface than at the 2, 4, 6, 10 or 12 cm height. Holding sperm for 10 min in liquid nitrogen vapor produced higher post-thaw motility and PMI than for 2, 5 or 20 min. The cryopreservation protocol developed in this study improved both post-thaw motility and PMI of O. angasi sperm at least 15% higher than those cryopreserved using programmable freezing method. Liquid nitrogen vapor freezing might have greater applicability in improving post-thaw sperm quality of spermcasting oyster species.     

Addition of procyanidine to semen preserves progressive sperm motility up to three hours of incubation

Several studies on semen physiology and sperm fertilizing capacity have shown a beneficial effect of antioxidants. Procyanidine is a natural antioxidant, more efficient compared with vitamin C and E, with many applications in the food, agriculture, pharmaceutical and cosmetic industry. Thus, we tested whether the addition of procyanidine to the semen of infertile men has a beneficial effect on spermatozoa during their in vitro incubation and during the cryopreservation process. Semen samples of 25 infertile men were divided in to two aliquots, in which procyanidine was added or not. Semen analysis, measurement of sperm DNA fragmentation index (DFI) and measurement of reactive oxygen species (ROS) were performed 3 h after incubation at 37 °C and after sperm cryopreservation and thawing. In-vitro addition of procyanidine to semen of infertile men resulted in a lesser decrease in progressive motility [−4 (−31:+6) vs. −6 (−31:+5), p < 0.001] and total motility [−5 (−29:+3) vs. −9 (−32:+2), p < 0.001] after 3 h of incubation compared with no addition of procyanidine. Sperm morphology was decreased only in the control group after 3 h of incubation [2 (0:+6) vs. 1 (0:+4), p = 0.009]. Furthermore, a larger increase in sperm DFI was observed in the control compared with the procyanidine group [9 (−7:+27) vs. 3 (−3:+18), p = 0.005] after thawing of cryopreserved semen samples. In conclusion, in-vitro addition of procyanidine to the semen of infertile men exerts a protective effect on progressive motility during handling and after 3 h of incubation as well as on sperm DFI during the process of cryopreservation.     

Improving viability of cryopreserved honey bee (Apis mellifera L.) sperm with selected diluents, cryoprotectants, and semen dilution ratios

This is the first study where the systematic application of theories and techniques used in mammalian sperm cryopreservation have been applied to honey bee (Apis mellifera L.) semen as a means to improve postthaw viability of cryopreserved sperm. Six newly designed diluents, three cryoprotectants (dimethyl sulfoxide, DMA, glycerol), and five diluent:semen ratios (1:1, 3:1, 6:1, 9:1, and 12:1) were tested. In addition, the sperm freezing tolerance of three honey bee strains was evaluated. Specific protocols were designed to control semen freezing and thawing rates. Sperm motility was assessed visually, whereas sperm viability was assessed using SYBR-14 and propidium iodide fluorescent stains. Diluent treatments did not affect fresh (nonfrozen) sperm viability yet affected fresh sperm motility (P < 0.05). Based on these assessments, two diluents were chosen and used in all successive cryopreservation experiments. Using the selected diluents, semen was collected at various diluent:semen ratios, along with one of the three cryoprotectants. Semen collected at high dilution ratios, using a hypotonic antioxidant diluent containing catalase, in combination with dimethyl sulfoxide, provided higher postthaw sperm viability than that of all other combinations tested (68.3 ± 5.4%; P < 0.05). Using this combination of dilution ratio, diluent, and cryoprotectant, there were no differences among honey bee strains for postthaw sperm viability (P = 0.805). Nevertheless, these new semen dilution and freezing methods improved postthaw viability of sperm to levels that could theoretically sustain worker populations in colonies, thus providing potential for further optimization of cryopreservation techniques for the genetic preservation and improvement of honey bee genotypes.     

Effect of insulin on functional parameters of human cryopreserved sperms

Cryopreservation of sperms is common therapy but with multiple damages to sperms. The aim of this study was to assess the effect of insulin as a prosurvival factor on the most important functional parameters of human spermatozoa during cryopreservation. Semen samples were obtained from 15 normozoospermic men at age 25–40 years of old through masturbation. Cryopreservation of sperms was conducted along with adding 10, 100, 500 and 1000 (ng/ml) insulin and a control group was also considered by adding distilled water. Samples were cryopreserved for 2 weeks in liquid nitrogen. Then, after thawing sperm motility; cytosolic/mitochondrial reactive oxygen species (ROS) levels; and DNA fragmentation were analyzed. Data were analyzed by SPSS software using one-way ANOVA. Results showed that insulin at all doses significantly decreased cytosolic ROS especially in 10 ng/ml group (P˂0.05). Mitochondrial ROS also decreased by adding insulin in comparison to the control group, although unmeaningfully (P˃0.05). Insulin at 1000 (ng/ml) decreased DNA fragmentation, significantly (P˂0.05). Also, the number of motile sperms increased in all insulin groups but it wasn't meaningful (P˃0.05). Based on our findings adding insulin to semen leads to protecting effects against cryopreservation damages and increases sperms motility. Therefore, using insulin for human semen seems to could be suggested for future clinical applications.     

Effect of straw size and thawing time on quality of cryopreserved buffalo (Bubalus bubalis) semen

This study was designed to compare the effect of straw size (0.25 vs. 0.5 ml) and thawing time (30 vs. 60 sec) on the quality of cryopreserved buffalo bull semen. Sperm motility, plasma membrane integrity and viability were higher (p ≤ 0.05) in 0.25 ml than 0.5 ml straw, thawed at 37°C either for 30 or 60 sec. In conclusion, cryopreservation of buffalo semen in 0.25 ml straw resulted in a higher post-thaw quality.     

Supplementation of freezing media with alpha lipoic acid preserves the structural and functional characteristics of sperm against cryodamage in infertile men with asthenoteratozoospermia

The aim of this study was to examine the effects of alpha lipoic acid (ALA) supplementation during semen cryopreservation on the sperm quality, chromatin integrity, oxidative stress, and expression level of BAX, BCL2, HSP70 and iNOS genes in semen samples obtained from infertile men with asthenoteratozoospermia.MethodsTwenty freshly ejaculated semen samples were cryopreserved with sperm freezing medium supplemented with 0.00, 0.02, 0.05, 0.1, 0.5, and 1 mmol/mL of ALA. The samples were analyzed according to the WHO guidelines before and after freezing. Sperm ROS production level, DNA fragmentation and cryo-capacitation were assessed using flow cytometry, TUNEL assay and chlortetracycline (CTC) test, respectively. Expression level of stress protein (HSP70), pro-apoptotic Bax, anti-apoptotic Bcl-2, and iNOS genes was assessed by real-time PCR assay.ResultsThe effective concentrations of ALA (0.02 and 0.5 mM) significantly improved the motility, viability and morphology of the frozen-thawed sperms compared to the control group treated with 0.00 mM of ALA. During cryopreservation, treatment of semen with 0.02 mM of ALA, as the optimal concentration, significantly decreased DNA fragmentation and oxidative stress level (P < 0.05), protected the acrosome integrity, and led to insignificant reduction in BAX gene expression level and significant increase in expression level of BCL2, HSP70, and iNOS genes compared with control group.ConclusionOur findings revealed that the adding ALA to semen samples obtained from infertile men with asthenoteratozoospermia plays a significant protective role against cryodamage by preserving the sperm functional parameters.