41 Effect of vitrification on DNA integrity of human spermatozoa

The aim of our study was to investigate the effect of vitrification with sucrose on swim-up-prepared human spermatozoa in comparison with standard, conventional manual freezing with permeable cryoprotectants. After informed consent, 35 ejaculates were obtained from 35 patients with normozoospermia who were patients of a fertility clinic. All specimens used for this study had fulfilled the following quality criteria for spermatozoa concentration and motility on IVOS (Hamilton Thorne). Semen analysis was performed according to published guidelines of the World Health Organization (WHO Laboratory Manual for the Examination and Processing of Human Semen, 2010). After swim-up, each sample was centrifuged, resuspended with the basic medium (human tubal fluid + 1% human serum albumin) to achieve a concentration of 5×106 spermatozoa/mL, and finally aliquoted into two equal subsamples. Each of these aliquots was assigned to one of two groups: group 1 included conventionally cryopreserved spermatozoa and group 2 included spermatozoa that were vitrified. For conventional cryopreservation, freezing media (15% (vol/vol) glycerol, 20% (vol/vol) egg yolk) and citrate was added to the washed spermatozoa in a 1:2 ratio. The sperm suspension was aspirated into 0.5-mL straws (CryoBioSystem). Subsequent to the room-temperature incubation for 10min, straws were placed horizontally in the vapour phase for 15min and then submerged into liquid nitrogen. For thawing, cryopreserved straws were immersed in water (23°C) for 5min. For preparation of vitrification solution, the basic medium (human tubal fluid + 1% human serum albumin) was diluted 1:1 with 0.5M sucrose. Immediately after processing, the sperm suspension was diluted in a 1:1 ratio with the vitrification solution to reach a final sucrose concentration of 0.25M. The vitrification and sperm solution (300μL) were aspirated into the straws 0.5mL. Straws were then left at room temperature (20-21°C) for 10min and subsequently submerged horizontally into the liquid nitrogen (Isachenko et al. 2012 J. Androl. 33, 462-468; https://doi.org/10.2164/jandrol.111.013789) and stored similarly to the conventionally cryopreserved straws. To thaw, vitrified straws were immersed in a water bath (42°C) for 20s. The DNA fragmentation was analysed using the APO DIRECT kit (BD PharmingenTM). The cells were stained according to the manufacturer's protocol, followed by flow cytometry analysis CyFlow (Sysmex-Partec). An analysis of variance with a significance of 0.05 for nonparametric statistical analysis to establish differences between groups was used. In our study, no statistically significant differences were observed in the total motility, progressive motility, or velocity parameters of spermatozoa (P>0.05) post-thawing. Also, higher percentages of DNA fragmentation (35.1±8.1% vs. 20.1±6.8%; P<0.05) were found in spermatozoa cryopreserved by means of vitrification with sucrose compared with conventional cryopreservation. Therefore, these methods are comparable and either can be implemented for the storage of spermatozoa to be used for future assisted-reproduction-technology procedures. Vitrification of human spermatozoa provides a simpler, faster, more cost-effective alternative to conventional cryopreservation methods.

156 Effect of human tubal fluid medium and hyperactivation inducers on stallion sperm capacitation and hyperactivation

Conventional IVF has not yet been implemented in the equine species. One of the main reasons has been the inability to develop a culture medium and incubation conditions supporting high levels of stallion sperm capacitation and hyperactivation in vitro. Although different culture media have been used for this purpose, human tubal fluid (HTF) medium, widely used in the manipulation of human and mice gametes, has not been reported so far in stallion sperm culture. Thus, the first part of this study aimed to compare HTF (Summers and Biggers, 2003 Hum. Reprod. Update9, 557-582, DOI: 10.1093/humupd/dmg039) and Whitten’s (McPartlin et al. 2009 Biol. Reprod.81, 199-206, DOI: 10.1095/biolreprod.108.074880) media on different stallion sperm quality and capacitation variables. Additionally, the effect of procaine, aminopyridine and caffeine on sperm motility parameters was evaluated in both media at different incubation times. Fresh semen from 3 Chilote stallions was collected, diluted to 10×106 sperm mL−1 in capacitating (7mg mL−1 BSA and 25mM NaHCO3) and non-capacitating (without BSA and NaHCO3) HTF and Whitten’s media and incubated for 30 and 120min at 38°C in air atmosphere. Integrity and destabilisation of the plasma membrane were evaluated by merocyanine 540/SYTOX Green (MC540), mitochondrial membrane potential (ΔΨm) using tetramethylrhodamine methyl ester perchlorate, acrosome membrane integrity by peanut agglutinin/fluorescein isothiocyanate and tyrosine phosphorylation by P-tyrosine mouse mAb conjugated to Alexa Fluor® in a FACSCanto II flow cytometer (Becton, Dickinson and Co., Franklin Lakes, NJ, USA). A total of 10,000 sperm events were acquired from each measurement (n=3 replicates for each stallion). Motility parameters were evaluated using the integrated semen analysis system (ISAS®, Selinion Medical, Brussels, Belgium). Percentage data were arcsine transformed and subjected to a 2-way ANOVA with Bonferroni’s post hoc test using Prism 7 software (GraphPad Software, La Jolla, CA, USA). We found no differences between Whitten’s and HTF media in terms of sperm viability, uninduced acrosome membrane damage or mitochondrial membrane potential at 30 and 120min of incubation. Membrane fluidity (MC540) increased in both media at 30 and 120min of incubation compared with non-capacitating conditions. Similarly, tyrosine phosphorylation increased in both media in capacitating conditions at 2 and 4h of incubation compared with non-capacitating conditions, without differences between media. Although procaine showed the best result in terms of sperm hyperactivated motility in both media, aminopyridine also showed parameters consistent with hyperactivation including an increase in curvilinear velocity and decrease in straightness. In conclusion, HTF medium and aminopyridine equally support capacitation-related parameters in stallion sperm. Funding support was received from FONDECYT 1160467 CONICYT, Chile.

Human spermatozoa vitrified in the absence of permeable cryoprotectants: birth of two healthy babies

Herein, we report the birth of two healthy babies to a woman following intracytoplasmic sperm injection (ICSI) using motile spermatozoa vitrified without permeable cryoprotectants. Spermatozoa (in a case of oligoasthenoteratozoospermia) were cooled in cut standard straws in human tubal fluid supplemented with 0.5% human serum albumin and 0.25 M sucrose. Sperm motility, capacitation-like changes, acrosome reaction and mitochondrial membrane potential (MMP) were compared in fresh and vitrified spermatozoa. Eight mature (MII) oocytes were microinjected with the vitrified–warmed motile spermatozoa. Although the motility of vitrified–warmed spermatozoa was markedly lower than that of fresh spermatozoa (60% v. 90%, respectively), there were no immediate visible differences in the percentages of capacitated and acrosome-reacted vitrified and fresh spermatozoa (10% v. 8% and 5% v. 8%, respectively). However, the MMP in vitrified spermatozoa was apparently adversely affected in the ejaculate used for ICSI compared with fresh spermatozoa (63% v. 96% spermatozoa with high MMP). Eighteen hours later, six oocytes showed signs of normal fertilisation. Two-pronuclear oocytes were cultured in vitro for 24 h and two four-blastomere embryos were transferred. Two healthy girls were born at term. Our findings suggest that permeable cryoprotectant-free vitrification can be applied successfully for some procedures in assisted reproduction, in particular in ICSI with motile vitrified spermatozoa, to achieve normal pregnancy and birth.

202 SEX PRE-SELECTION IN RABBITS: AN ATTEMPT TO SKEW OFFSPRING SEX THROUGH PERCOLL AND SWIM-UP SPERM PREPARATION TECHNIQUES

Sperm preparation techniques could have an effect on the birth ratio (male vs female offspring) through enrichment of either X- or Y-bearing sperm populations, although studies have been poorly controlled and results have been inconclusive. In the rabbit, producers may be interested in producing a majority of males (meat producing systems) or females (hybrid producing systems). The objective of this study was to evaluate the effect of modified Percoll and Swim-up protocols on the enrichment of the male and female birth ratios in rabbits. Four hybrid mature bucks of adequate body condition score and proven fertility were used. The same four bucks were used throughout the study (8 replicates). Ejaculates were collected using a warmed, solid, artificial vagina. Progressive motility was assessed at 200× magnification under brightfield microscopy on a heated (37°C) stage. Sperm concentration for each buck was determined using a Neubaur chamber and adjusted (350 × 106 total spermatozoa mL–1); they were then combined (1 mL/buck) to form a heterospermic sample (final heteropsermic sample volume = 4 mL). The heteropsermic sample was then divided into 3 sperm preparation treatments: (1) diluted in commercial tri-buffered extender followed by immediate AI (control); (2) modified Percoll centrifugation in a 90 to 45% density gradient (diluted in human tubal fluid medium); and (3) Swim-up (in human tubal fluid medium). In total, 125 females were inseminated. Does were treated with PMSG (20 UI/doe, 48 h before AI) and inseminated with 30 to 40 × 106 spermatozoa; ovulation was induced with 20 μg of gonadotropin-releasing hormone (GnRH)/doe immediately after AI. Sex of newborn kits was determined 35 days after birth by an experienced technician through external visualization of genitalia. Results were statistically analyzed using ANOVA and Tukey test (Infostat). The insemination of does with heterospermic ejaculates (control) resulted in a progeny distribution of 49 ± 2% males and 51 ± 2% females, which is in good agreement with the expected theoretical 50:50 ratio. Sex ratios from modified Percoll and Swim-up treatments deviated significantly from the control (P < 0.01). Percoll gradient resulted in a progeny distribution of 32 ± 2% males and 68 ± 2% females; Swim-up resulted in a 64 ± 2% male and a 36 ± 2% female distribution (P < 0.01), whereas prolificacy, perinatal mortality and birth weight were not affected by treatment (Table 1). Our results indicate sperm preparation techniques could be used to skew birth ratios towards male or female offspring in rabbits; Percoll preparation could be used to increase proportion of female kits whereas Swim-up could be used to increase the proportion of males. Further studies are needed to determine the underlying mechanisms of action. Table 1.Progeny distribution after Percoll or Swim-up sperm preparation in rabbits