Post-thaw survival, cell death and actin cytoskeleton in gene-microinjected rabbit embryos after vitrification

In vitro effect of ferrous sulphate on bovine spermatozoa motility parameters, viability and Annexin V-labeled membrane changes

The aim of this study was to assess the dose- and time-dependent in vitro effects of ferrous sulphate (FeSO₄.7H₂O) on the motility parameters, viability, structural and functional activity of bovine spermatozoa. Spermatozoa motility parameters were determined after exposure to concentrations (3.90, 7.80, 15.60, 31.20, 62.50, 125, 250, 500 and 1000 μM) of FeSO₄.7H₂O using the SpermVision^TM CASA (Computer Assisted Semen Analyzer) system in different time periods. Cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay, and the Annexin V-Fluos was applied to detect the membrane integrity of spermatozoa. The initial spermatozoa motility showed increased average values at all experimental concentrations compared to the control group (culture medium without FeSO₄.7H₂O). After 2 h, FeSO₄.7H₂O stimulated the overall percentage of spermatozoa motility at the concentrations of ≤ 125 μM. However, experimental administration of 250 μM of FeSO₄.7H₂O significantly (P < 0.001) decreased the spermatozoa motility but had no negative effect on the cell viability (P < 0.05) (Time 2 h). The lowest viability was noted after the addition of ≥ 500 μM of FeSO₄.7H₂O (P < 0.001). The concentrations of ≤ 62.50 μM of FeSO₄.7H₂O markedly stimulated (P < 0.001) spermatozoa activity after 24 h of exposure, while at high concentrations of ≥ 500 μM of FeSO₄.7H₂O the overall percentage of spermatozoa motility was significantly inhibited (P < 0.001) and it elicited cytotoxic action. Fluorescence analysis confirmed that spermatozoa incubated with higher concentrations (≥ 500 μM) of FeSO₄.7H₂O displayed apoptotic changes, as detected in head membrane (acrosomal part) and mitochondrial portion of spermatozoa. Moreover, the highest concentration and the longest time of exposure (1000 μM of FeSO₄.7H₂O; Time 6 h) induced even necrotic alterations to spermatozoa. These results suggest that high concentrations of FeSO₄.7H₂O are able to induce toxic effects on the structure and function of spermatozoa, while low concentrations may have the positive effect on the fertilization potential of spermatozoa.

Finding an Effective Freezing Protocol for Turkey Semen: Benefits of Ficoll as Non-Permeant Cryoprotectant and 1:4 as Dilution Rate

Simple Summary

The most adopted biotechnology for the conservation of genetic resources in avian species is semen cryopreservation. Therefore, the identification of a reference cryopreservation procedure represents a key point for ensuring the long-term conservation of genetic diversity in birds, through the implementation of a semen cryobank. In this study, our goal was to discover an effective freezing protocol for Meleagris gallopavo in order to realize the first Italian semen cryobank of autochthonous chicken and turkey breeds within our project (TuBAvI). For this purpose, we investigated the effects of three non-permeant cryoprotectants (sucrose, trehalose, and Ficoll) and two dilution rates (1:2 and 1:4) on the in vitro cryosurvivability of turkey spermatozoa. After thawing, the best semen quality was found in semen frozen in the presence of Ficoll and diluted at a final rate of 1:4. This paper provides encouraging results, however further studies are programmed to standardize the semen cryopreservation protocol.

Abstract

The present study aimed to find an effective cryopreservation protocol for turkey semen through the combined use of dimethylsulfoxide (DMSO) and three non-permeant cryoprotectants (NP-CPAs), sucrose, trehalose, and Ficoll 70. In addition, the action of two dilution rates (1:2 and 1:4) were also investigated. Semen was processed according to two final dilution rates and the following treatments: Tselutin extender (TE)/DMSO (control), TE/DMSO + sucrose or trehalose 50, 100, 200, or 400 mM, and TE/DMSO + Ficoll 0.5, 0.75, 1, or 1.5 mM. In total 26 different combinations treatments were achieved. The diluted semen was filled up into straws and frozen on liquid nitrogen vapor. The post-thawing sperm quality was assessed by analyzing motility, membrane integrity, osmotic resistance, and DNA integrity. The results obtained revealed a significant effect of NP-CPA concentration on total and progressive motility, on most of the kinetic parameters, on membrane integrity and DNA integrity, while the post-thaw quality was less affected by dilution rate. The highest post-thaw quality for all sperm quality parameters assessed except curvilinear velocity (VCL) and DNA integrity were found in semen frozen with 1 mM Ficoll/1:4 (p < 0.05). Our findings provide an important contribution for the identification of a reference procedure for turkey semen cryopreservation, in order to create the first national avian semen cryobank.

The cryoprotective effect of Ficoll 70 on the post-warming survival and quality of Cryotop-vitrified donkey embryos

Many domestic donkey breeds are at risk of extinction, there is a critical urgency for genome resource banking. In the present study, we examined whether the use of Ficoll 70 added to the vitrification medium containing ethylene glycol (EG), dimethyl sulfoxide (DMSO) and sucrose improves the cryotolerance of donkey in vivo derived embryos. Day 7-8, grade 1-2 donkey embryos were measured and morphologically evaluated and then vitrified-warmed using the Cryotop technique. Before vitrification, embryos were randomly distributed into two groups: (i) VS1 (n = 14): vitrified using 15% EG + 15% DMSO + 0.5 M sucrose; and (ii) VS2 (n = 10): vitrified in the same medium supplemented also with 18% of Ficoll 70. After 24 h of warming, the embryos were measured and evaluated for their morphology, development and viability (Propidium Iodide-Hoechst 33342 dyes). Post-warming survival was numerically higher but not significantly different (P > 0.05) when embryos were vitrified in VS2 (70%) compared to VS1 (57.1%). Embryo rupture was only observed in the VS1 group (21.4%, 3/14). Higher embryo diameter was observed in all groups after 24 h culture (P < 0.05). No significant differences (P > 0.05) were observed among treatments in terms of percentages of cell death. These results demonstrate that the addition of Ficoll 70 to the vitrification medium is not a pre-requisite for successful vitrification of donkey embryos. However, its addition seems to enhance some of the post-warming embryo quality characteristics. Since no statistically significant evidence was found, further studies should be conducted in order to confirm our findings.

Effect of cryoprotectants and thawing temperatures on chicken sperm quality

There is need for standardization of freezing-thawing protocol for rooster semen to minimize variability among results. Therefore, we aimed to compare effect of four different permeating cryoprotectants and two thawing temperatures (37 vs. 5°C) on sperm post-thaw motility and to analyse combined effect of the best permeating cryoprotectant (P-CPA) with one of four non-permeating cryoprotectants (N-CPA) on post-thaw quality of rooster semen evaluated in vitro. Pooled semen from Ross PM3 rooster heavy line was diluted in Kobidil extender and frozen in cryoprotectant solution containing 6% dimethylacetamide, 7.5% dimethylformamide, 9% N-methylacetamide or 8% ethylene glycol (EG) in liquid nitrogen vapours. To determine the best thawing rate, straws were thawed either at 37 or 5°C. Furthermore, samples were frozen in the presence of the best N-CPA either with 0.75 mol/L ficoll, 0.2 mol/L sucrose, 0.2 mol/L trehalose or 0.05 mol/L glycine. Sperm motility, membrane destabilization and viability were analysed to compare different freezing-thawing conditions. In addition, morphology and ultrastructure analysis were performed to compare fresh and frozen-thawed sperm quality. Our results indicate that the combination of EG and the thawing at 5°C improves (p ≤ .05) sperm post-thaw motility. Moreover, ficoll addition to EG-based freezing extender provided additional beneficial effect (p ≤ .05) on progressive movement and apoptosis incidence. Further work should evaluate different N-CPA concentrations to improve freezing protocol. In addition, fertility evaluation and testing on different chicken lines are needed in order to contribute to animal genetic resources bank.

Efficient long-term cryopreservation of pluripotent stem cells at -80 °C

Current long term cryopreservation of cell stocks routinely requires the use of liquid nitrogen (LN₂), because commonly used cryopreservation media containing cell membrane permeating cryoprotectants are thermally unstable when frozen at higher storage temperatures, e.g. -80 °C. This instability leads to ice recrystallization, causing progressive loss of cell viability over time under the storage conditions provided by most laboratory deep freezers. The dependency on LN₂ for cell storage significantly increases operational expense and raises issues related to impaired working efficiency and safety. Here we demonstrate that addition of Ficoll 70 to cryoprotectant solutions significantly improves system thermal stability at the working temperature (~-80 °C) of laboratory deep freezers. Moreover, a medium comprised of Ficoll 70 and dimethyl sulfoxide (DMSO) in presence or absence of fetal bovine serum (FBS) can provide reliable cryopreservation of various kinds of human and porcine pluripotent stem cells at -80 °C for periods that extend up to at least one year, with the post-thaw viability, plating efficiency, and full retention of pluripotent phenotype comparable to that achieved with LN₂ storage. These results illustrate the practicability of a promising long-term cryopreservation method that completely eliminates the need for LN₂.

State of actin cytoskeleton and development of slow-frozen and vitrified rabbit pronuclear zygotes

This study was focused on the effect of cryopreservation on the state of actin cytoskeleton and development of rabbit pronuclear zygotes. Zygotes were collected from superovulated females and immediately used for 1) slow-freezing in a solution containing 1.5 M 1,2-propanediol and 0.2 M sucrose, or 2) vitrification in a solution containing 42.0% (v/v) of ethylene glycol, 18.0% (w/v) of dextran and 0.3 M sucrose as cryoprotectants. After thawing or warming, respectively, zygotes were evaluated for 1) actin distribution, 2) in vitro or 3) in vivo development to blastocyst. Comparing actin filaments distribution, a significantly higher number of vitrified zygotes with actin distributed in cell border was observed (55 ± 7.7 vs. 74 ± 6.1% for slow-frozen vs. vitrified, respectively). After 24 and 72 h of in vitro development, significant differences in the cleavage and morula rate among the groups were observed (9 ± 2.4 and 3 ± 1.3 vs. 44 ± 3.0 and 28 ± 2.7% for slow-frozen vs. vitrified, respectively). None of the slow-frozen zygotes reached the blastocyst stage, in contrast to the vitrified counterparts (11 ± 1.9%). Under in vivo culture conditions, a significant difference in blastocyst rate was observed between vitrified and fresh embryos (6 ± 1.5 vs. 35 ± 4.4% respectively). Our results showed that alterations in actin cytoskeleton and deteriorated development are more evident in slow-frozen than vitrified pronuclear zygotes. Vitrification method seems to be a more effective option for rabbit zygotes cryopreservation, although pronuclear zygotes manipulation per se resulted in a notable decrease in embryo development.

The cryoprotective effect of Ficoll on the rabbit spermatozoa quality

The aim of this study was to evaluate the effect of the addition of Ficoll 70 into the cryopreservation medium containing sucrose and dimethyl sulfoxide (DMSO) on rabbit spermatozoa characteristics following freezing/thawing. This large molecular weight polymer elevates the viscosity of medium and, therefore, could better protect spermatozoa during the freezing process. Only ejaculates of good initial motility (>80%) were used in the experiments. Heterospermic pools were diluted in a freezing medium composed of commercial diluent, 16% dimethyl sulphoxide (DMSO) and 2% sucrose (control) or in the same medium enriched with 4% Ficoll 70 (Ficoll) and frozen in liquid nitrogen vapours for 10 min before being plunged in liquid nitrogen. The quality of fresh and frozen/thawed spermatozoa samples was evaluated in vitro using the Computer Assisted Semen Analysis (CASA) system, fluorescent probes (peanut agglutinin (PNA)-Alexa Fluor®; annexin V-FLOUS) and by electron microscopy. Better cryoprotective effect was observed when Ficoll 70 was added, compared with the semen cryopreserved with sucrose and DMSO only. The higher values (P < 0.05) of motile and progressively moving spermatozoa immediately after thawing and at 30 min following incubation at 37°C were obtained in the Ficoll group. Moreover, the higher number (P < 0.05) of acrosome intact sperm was found in the Ficoll compared with the control group. Furthermore, no significant differences in kindling rates and number of pups born between frozen/thawed and fresh semen group were found. In conclusion, our study showed that the addition of Ficoll 70 might improve several characteristics of rabbit spermatozoa measured in vitro following freezing/thawing.

Ultrastructure of vitrified rabbit transgenic embryos

The aim of the study was to determine the viability of rabbit transgenic (enhanced green fluorescent protein (EGFP)-positive) embryos cultured in vitro and compare with gene-microinjected (Mi) non-transgenic (EGFP-negative) embryos following vitrification. Non-microinjected and non-vitrified embryos were used as the control. Morphological signs of injury to embryo organelles were determined at the ultrastructural level using transmission electron microscopy (TEM). Morphometric evaluation was performed on cellular organelles using microphotographs obtained by TEM. Intact and Mi embryos recovered from in vivo fertilized eggs at 19-20 hours post coitum (hpc) were cultured for up to 72 hpc (morula stage), evaluated for the EGFP gene integration and then vitrified in 0.25 ml insemination straws in modified EFS (40% ethylene glycol + 18% Ficoll 70 + 0.3 M sucrose) vitrification solution. After 1-3 days the embryos were devitrified, a representative selection of embryos was analyzed by TEM and the remaining embryos were subjected to additional in vitro culture. Observations by TEM showed that the vitrified/warmed EGFP-positive and EGFP-negative embryos had a slight accumulation of cellular debris and lipid droplets compared with the control intact embryos. More severe changes were detected in the membrane structures of the treated embryos, mostly in the cytoplasmic envelope, trophoblastic microvilli, junctional contacts and mitochondria. We suggest that the higher proportion of deteriorated cell structures and organelles in the treated embryos may be due to the vitrification process rather than to mechanical violation (the gene-microinjection procedure), as a detailed inspection of ultrastructure revealed that most damage occurred in the cell membrane structures.

Delaying embryo development by storing at 4°C for synchronization to recipients in microinjection technique in rabbits

Short-term storage of embryos at low temperature induces developmental arrest of the embryo and would appear to be a valuable aid in embryo-transfer techniques to avoid wasting embryos. Embryo storage at 4°C was examined to allow synchronization with embryo-transfer recipients using the microinjection technique. Superovulation was induced in female Japanese White donor rabbits four days before mating with males. At the same time, control recipients were injected with human chorionic gonadotropin (hCG) to allow synchronization (R1); the hCG injections were delayed by 24 h in the experimental group (R2). DNA constructs for expressing human C-reactive protein or apolipoprotein AII were microinjected into the male pronuclei of the ova. The microinjected embryos were immediately transferred to recipients (R1) or stored at 4°C in phosphate-buffered saline containing 10% fetal bovine serum. After 17-20 h, the stored embryos were incubated at 37°C for one hour, and the morphologically normal embryos were transferred to recipients (R2). In the R1 rabbits, 855 embryos were transferred to 29 recipients, and 72.4% of the recipients became pregnant. Seven of the 84 offspring were transgenic. In the R2 rabbits, 478 embryos were transferred to 16 recipients, and 62.5% of the recipients became pregnant. Two of the 39 offspring were transgenic. There were no differences in pregnancy rate, litter size and transgenic integration rate between R1 and R2. These results suggest that the short-term 4°C storage of microinjected embryos can be a valuable method for synchronization with recipients, and reducing wastage of embryos and the sacrifice of rabbits.

Quality of rabbit vitrified/thawed transgenic embryos

The aim of our study was to investigate the influence of vitrification on developmental rate and quality (total number of cells, number of blastomeres in inner cell mass (ICM) area, apoptotic index and embryo diameter) of transgenic (carrying an endogenous–hFVIII or exogenous–enhanced green fluorescent protein (EGFP) gene) rabbit embryos. EGFP-positive rabbit embryos were produced under in vitro conditions by the microinjection of foreign genes into the pronucleus of fertilized eggs. The transgenic rabbit embryos with the hFVIII gene were produced by mating homozygous transgenic rabbits and flushing at the single-cell stage. Developmental rate of vitrified/thawed transgenic embryos that reached hatching blastocyst stage (68.00% and 69.00%) and differed significantly (p < 0.001) from those in control embryos (100.00%). Significant difference (p < 0.05) was found in total cell counts between control (117.00 ± 36.00) and vitrified (141.00 ± 34.80) hFVIII-positive embryos. The higher proportion of ICM cells (32.00%) and greatest embryo diameter (130.85 ± 10.90) were found in the control group compared with the transgenic. Ratio of apoptotic cells was significantly higher (p < 0.01) in the control group (2.50%) and vitrified EGFP-positive embryos (2.90%) compared with the vitrified, hFVIII-positive group of embryos (0.70%). Our results demonstrate that neither gene microinjection itself, nor exogenous (EGFP) and endogenous (hFVIII) gene expression interferes with developmental rate and quality of rabbit embryos. However, a combination of microinjection and vitrification significantly decreases (p < 0.001) the survival rate of rabbit embryos.

Assessment of actin cytoskeleton and nuclei in bovine blastocysts developed under different culture conditions using a novel computer program

This study was performed to investigate the effects, in terms of nuclear material and actin cytoskeleton quantities (fluorescent pixel counts), of four different bovine blastocyst culturing techniques (in vitro, stepwise in vitro-to-in vivo, or purely in vivo). Cumulus oocyte complexes from abattoir-sourced ovaries were matured in vitro and allocated to four groups: IVP-group embryos developed up to blastocyst stage in vitro. Gamete intra-fallopian transfer (GIFT)-group oocytes were co-incubated with semen for 4 h before transfer to oviducts of heifers. Following in vitro fertilization, cleaved embryos (day 2 of embryo development, day 2-7 group) were transferred into oviducts on day 2. Multiple ovulation embryo transfer (MOET)-group embryos were obtained by superovulating and inseminating heifers; the heifers' genital tracts were flushed at day 7 of blastocyst development. Within each group, ten blastocysts were selected to be differentially dyed (for nuclei and actin cytoskeleton) with fluorescent stains. A novel computer program (ColorAnalyzer) provided differential pixel counts representing organelle quantities. Blastocysts developed only in vivo (MOET group) showed significantly more nuclear material than did blastocysts produced by any other technique. In terms of actin cytoskeleton quantity, blastocysts produced by IVP and by day 2-7 transfer did not differ significantly from each other. Gamete intra-fallopian transfer- and MOET-group embryos showed significantly larger quantities of actin cytoskeleton when compared with any other group and differed significantly from each other. The results of this study indicate that culturing under in vitro conditions, even with part time in vivo techniques, may adversely affect the quantity of blastocyst nuclear material and actin cytoskeleton. The software employed may be useful for culture environment evaluation/developmental competence assessment.

Post-thaw culture in presence of insulin-like growth factor I improves the quality of cattle cryopreserved embryos

The goal of this study was to examine the effect of insulin-like growth factor I (IGF-I; added during post-thaw culture (48 h)) on the preimplantation viability and quality of cryopreserved bovine in vivo recovered embryos. The morula stage embryos, non-surgically recovered from superovulated dairy cows of Czech Fleckvieh cattle breed, had previously been cryopreserved by a slow freezing technique and stored in liquid nitrogen since 1989–1990. Following thawing, the embryos were cultured for 48 h either alone (no IGF-I) or in the presence of IGF-I (10 or 100 ng/ml); non-cultured embryos served as a control. Thereafter, the embryos were analyzed for cleavage to the blastocyst stage, apoptosis (TUNEL), embryo cell number and quality of actin cytoskeleton. Following post-thaw culture 41% of embryos developed to advanced blastocysts. IGF-I increased this per cent and, at a higher dose, essentially reduced the per cent of degenerated embryos. In cultured embryos, IGF-I at both doses elevated the cell number compared with non-cultured embryos. However, in comparison with embryos cultured without IGF-I, only the higher IGF-I dose resulted in elevating the embryo cell number. The TUNEL index was significantly lowered by IGF-I treatment. Thawed embryos were mostly of the grade III actin type and fewer (12%) had grade II actin, whilst no grade I actin embryos were noted. The addition of IGF-I resulted in the appearance of grade I actin embryos (8.33 and 6.9% for 10 and 100 ng/ml, respectively). These observations indicate that the addition of IGF-I during post-thaw culture can improve the quality of bovine cryopreserved embryos.

In vitro effect of nickel on bovine spermatozoa motility and annexin V-labeled membrane changes

In this study the effect of in vitro culture of bovine spermatozoa with nickel (NiCl(2)) on spermatozoa motility and membrane changes was analyzed. The spermatozoa motility significantly decreased after 120 min of culture at the concentration of 1000 μM Ni ml(-1) (P < 0.05) and after 240 min of culture at the concentration of 500 and 1000 μM Ni ml(-1) (P < 0.001) as compared with control. The progressive motility was the highest in the control group and in the groups with the lowest nickel concentrations (7.8 and 125 μM Ni ml(-1)). The progressive spermatozoa motility was significantly altered even after 30 min of culture in the group with the highest nickel concentration (1000 μM Ni ml(-1)). A significant decrease in progressive motility from the concentration of 250 μM Ni ml(-1) was detected after 240 min of culture. Concentrations from 125 μM Ni ml(-1) in various time periods of culture stimulated spermatozoa motility after 30 min (P < 0.001), but later an inhibitory effect was noted. After 240 min of in vitro spermatozoa culture with 125 μM Ni ml(-1) a typical Annexin V fluorescence reaction was detected. Fluorescence was detected in mitochondrial segment of bovine spermatozoa. In spermatozoa exposed to higher nickel concentrations the Annexin V-positive reaction was detected also on the spermatozoa head membrane. In the group with the highest concentration and the longest time of exposure (1000 μM Ni ml(-1); 240 min) the apoptotic Annexin-positive regions were detected not only in the mitochondrial part, but also in the spermatozoa head (acrosomal and postacrosomal part), showing significant alteration of spermatozoa membrane integrity.

Evaluation of vitrification for cryopreservation of teeth

Purpose

The aim of this study was to investigate whether vitrification in the cryopreservation of periodontal ligament (PDL) cells could be useful for tooth banking.

Methods

In step 1, primary cultured human PDL cells were cryopreserved in 100% conventional cryopreservation media and 100% vitrification media (ESF40 media) in different temperatures for 2 weeks. In step 2, a series of modified vitrification formulae named T1 (75% vitrification media + 25% F-media), T2 (50% vitrification media + 50% F-media) and T3 (25% vitrification media + 75% F-media) were used to store PDL cells for 2 weeks and 4 weeks in liquid nitrogen. MTT assay was performed to examine the viability of PDL cells.

Results

Maximum cell viability was achieved in cells stored in 100% conventional cryopreservation media at -196℃ (positive control group) in step 1. Compared to the positive control group, viability of the cells stored in 100% vitrification media was very low as 10% in all test conditions. In step 2, as the percentage of vitrification media decreased, the cell viability increased in cells stored for 2 weeks. In 4-week storage of cells in step 2, higher cell viability was observed in the T2 group than the other vitrification formulae while the positive control group had the highest viability. There was no statistically significant difference in the cell viability of 2-week and 4-week stored cells in the T2 group.

Conclusions

These observations indicate 100% vitrification media is not successful in PDL cell cryopreservation. Conventional cryopreservation media is currently the most appropriate media type for this purpose while T2 media would be interesting to test for long-term storage of PDL cells.

Superfine open pulled straws vitrification of porcine blastocysts does not require pretreatment with cytochalasin B and/or centrifugation

The present study investigated the in vitro development of and cytoskeletal disruption suffered by in vivo-derived porcine blastocysts subjected to superfine open pulled straws (SOPS) vitrification. Blastocysts were either untreated prior to SOPS vitrification or were subjected to one of the following three pretreatment protocols: (1) centrifugation (12 min, 13 000g); (2) 25 min equilibration with 7.5 μg mL–1 cytochalasin B; or (3) equilibration with cytochalasin B followed by centrifugation. After 24 h culture, fresh (n = 32) and vitrified–warmed (n = 188) blastocysts were evaluated by stereomicroscopy, with survival and hatching rates recorded. Some blastocysts were stained with 4′,6′-diamidino-2-phenylindole and processed for cytoskeletal evaluation. Three cytoskeletal patterns were identified: Grade I, intact cytoskeleton; Grade II, gross maintenance of integrity, but with some clumps of actin within the cytoplasm; and Grade III, a highly disrupted cytoskeleton. There were no differences in the survival, hatching and cell death rats, total cell number or cytoskeletal integrity between the different vitrification groups. Cell death was greater for vitrified blastocysts than for fresh blastocysts (3.6 ± 0.4% v. 0.4 ± 0.7%, respectively; P < 0.05) and the percentage of blastocysts with a Grade I cytoskeletal pattern was lower for vitrified compared with fresh blastocysts (60.8% v. 92%, respectively; P < 0.05). The vitrified–warmed blastocysts that hatched during culture exhibited a Grade I cytoskeletal pattern. In conclusion, successful SOPS vitrification of porcine blastocysts does not require pretreatment with cytochalasin B and/or centrifugation.

Several aspects of animal embryo cryopreservation: anti-freeze protein (AFP) as a potential cryoprotectant

With the development of embryo technologies, such as in vitro fertilization, cloning and transgenesis, cryopreservation of mammalian gametes and embryos has acquired a particular interest. Despite a certain success, various cryopreservation techniques often cause significant morphological and biochemical alterations, which lead to the disruption of cell organelles, cytoskeleton damages, cell death and loss of embryo viability. Ultrastructural studies confirm high sensitivity of the cell membrane and organelle membrane to freezing and thawing. It was found that many substances with low molecular weights have a protective action against cold-induced damage. In this concern, an anti-freeze protein (AFP) and anti-freeze glycoproteins (AFGPs), which occur at extremely high concentrations in fish that live in Arctic waters and protect them against freezing, may be of potential interest for cryostorage of animal embryos at ultra-low temperatures. This mini-review briefly describes several models of AFP/AFGP action to preserve cells against chilling-induced damages and indicates several ways to improve post-thaw developmental potential of the embryo.