Background: Using cryovial for freezing dog spermatozoa provides a practical method to increase extended sperm volume and shorten the time required for equilibration by using a simple freezing techniques. The purpose of this study was to determine the optimal thawing condition for dog sperm cryopreservation using cryovials. Methods: For sperm freezing, cryovials with 200 × 106 sperm/mL were cooled after the addition of tris egg yolk extender (TEY) at 4℃ for 20 min, then TEY with 4% glycerol was added and equilibrated for another 20 min before being aligned over LN2 vapor for another 20 min and plunged directly into LN2. Spermatozoa were thawed in a water bath at 37℃ for varying times (25 sec, 60 sec, 90 sec, and 120 sec) in the first experiment. In the second experiment, spermatozoa were thawed in a water bath at various temperatures and times (37℃ for 1 min, 37℃ for 1 min with gentle stirring, 24℃ for 24 min, and 75℃ for 20 sec). In these experiments, the effect of thawing conditions on motility parameters, viability (SYBR-14/PI), and acrosome integrity (PSA/ FITC) of spermatozoa were investigated. Results: The post-thaw sperm motility parameters, viability, and acrosome integrity were not significantly different across the experimental groups. Conclusions: In this study, the characteristics of spermatozoa frozen using cryovials were not significantly affected by various thawing conditions.

본 연구는 동자개 정자의 동결보존을 위해 동결보존제의 최적 농도와 적정 희석액을 구명하여 정자를 최상의 상태로 보존하여 인공종자를 생산하는데 목적이 있다. 실험은 3종의 희석액(Ⅰ: 300 mM glycose, Ⅱ: Kurokura extender, Ⅲ: Li extender), 4종의 동결보존제(dimethyl sulfoxide, ethylene glycol, methanol and glycerol)와 4개의 동결보존제 농도(5, 10, 15, 20%)를 조합하여 대하여 조사하였다. 동결보존한 정자를 해동한 후 정자의 생존율과 정자활성지수로 동결보존 제의 효과를 평가하였다. 희석액 Ⅲ(Li extender)과 10과 15%의 methanol을 조합했을 때 동자 개 정자의 생존율과 정자활성지수는 각각 66.9 ± 8.7, 67.3 ± 13.1%과 2.6 ± 0.4, 2.6 ± 0.5로 다른 희석액과 동결보존제보다 높았다.

Despite numerous advances in in-vitro embryo production (IVP), many documented factors have been shown to influence the development of mammalian preimplantation embryos and the success of IVP. In this sense, elevated levels of reactive oxygen species (ROS) correlate with poor outcomes in assisted reproductive technologies (ART) due to oxidative stress (OS), which results from an imbalance between ROS production and neutralization. Indeed, excessive production of ROS compromises the structural and functional integrity of gametes and embryos both in vivo and in vitro. In particular, OS damages proteins, lipids, and DNA and accelerates cell apoptosis. Several in-vivo and in-vitro studies report an improvement in qualityrelevant parameters after the use of various antioxidants. In this review, we focus on OS and the source of free radicals and their effects on oocytes, sperm, and the embryo during IVP. In addition, antioxidants and their important role in IVP, supplementation during oocyte in vitro maturation (IVM), in vitro culture (IVC), and semen extenders were discussed. Nevertheless, various methods for determining the level of ROS in germ cells have been briefly described. Still, it is crucial to develop standardized antioxidant supplement systems to improve overall IVP success. Further studies should explore the safety, efficacy, mechanism of action, and combination of different antioxidants to improve IVP outcomes.

Epididymal sperm cryopreservation provides a potential method for preserving genetic material from males of endangered species. This pilot study was conducted to develop a freezing method for tiger epididymal sperm. We evaluated post-thaw sperm condition using testes with intact epididymides obtained from a Siberian tiger (Panthera tigris altaica ) after castration. The epididymis was chopped in Tyrode's albumin-lactate-pyruvate 1x and incubated at 5% CO2, 95% air for 10 min. The Percoll separation density gradient method was used for selective recovery of motile spermatozoa after sperm collection using a cell strainer. The spermatozoa were diluted with modified Norwegian extender supplemented with 20 mM trehalose (extender 1) and subsequent extender 2 (extender 1 with 10% glycerol) and frozen using LN2 vapor. After thawing at 37℃ for 25 s, Isolate® solution was used for more effective recovery of live sperm. Sperm motility (computerized assisted sperm analysis, CASA), viability (SYBR-14 and Propidium Iodide) and acrosome integrity (Pisum sativum agglutinin with FITC) were evaluated. The motility of tiger epididymal spermatozoa was 40.1 ± 2.0%, and progressively motile sperm comprised 32.7 ± 2.3%. Viability was 56.3 ± 1.6% and acrosome integrity was 62.3 ± 4.4%. Cryopreservation of tiger epididymal sperm using a modified Norwegian extender and density gradient method could be effective to obtain functional spermatozoa for future assisted reproductive practices in endangered species.

Sperm cryopreservation is a fundamental process for the long-term conservation of livestock genetic resources. Yet, the packaging method has been shown, among other factors, to affect the frozen-thawed (FT) sperm quality. This study aimed to develop a new mini-straw for sperm cryopreservation. In addition, the kinematic patterns, viability, acrosome integrity, and mitochondrial membrane potential (MMP) of boar spermatozoa frozen in the developed 0.25 mL straw, 0.25 mL (minitube, Germany), or 0.5 mL (IMV technologies, France) straws were assessed. Postthaw kinematic parameters were not different (experiment 1: total motility (33.89%, 32.42%), progressive motility (19.13%, 19.09%), curvilinear velocity (42.32, 42.86), and average path velocity (33.40, 33.62) for minitube and the developed straws, respectively. Further, the viability (38.56%, 34.03%), acrosome integrity (53.38%, 48.88%), MMP (42.32%, 36.71%) of spermatozoa frozen using both straw were not differ statistically (p > 0.05). In experiment two, the quality parameters for semen frozen in the developed straw were compared with the 0.5 mL IMV straw. The total motility (41.26%, 39.1%), progressive motility (24.62%, 23.25%), curvilinear velocity (46.44, 48.25), and average path velocity (37.98, 39.12), respectively, for IMV and the developed straw, did not differ statistically. Additionally, there was no significant difference in the viability (39.60%, 33.17%), acrosome integrity (46.23%, 43.23%), and MMP (39.66, 32.51) for IMV and the developed straw, respectively. These results validate the safety and efficiency of the developed straw and highlight its great potential for clinical application. Moreover, both 0.25 mL and 0.5 mL straws fit the present protocol for cryopreservation of boar spermatozoa.

Sperm cryopreservation is an important method of assisted reproductive techniques and storing genetic resources. It plays a vital role in genetic improvement, livestock industrial preservation of endangered species, and clinical practice. Consequently, the cryopreservation technique is well organized through various studies, especially on Korean native cattle (Hanwoo). However, the cryopreservation technique of Korean native brindled cattle, which is one of the native cattle species in Korea, is not well organized. Therefore, it is necessary to develop a Supplementary Table technique for the cryopreservation of Korean native brindled cattle. For this purpose, it is important to first evaluate the quality of the currently produced cryopreserved sperm of Korean native brindled cattle. In this study, we randomly selected 72 individual Korean native brindled cattle semen samples collected from 8 different region research centers and used them to evaluate sperm functions. We focused on the quality evaluation of cryopreserved Korean native brindled cattle semen following the measurement of motion kinematics, capacitation status, intracellular ATP level, sperm motility, and cell viability. Then, the values of each of the eight groups were derived from various sperm parameters of nine individual samples, including sperm motility, kinematics, cellular motility, and intracellular ATP levels, which were used to compare and evaluate sperm function. Overall, differences in various sperm parameters were observed between most of the research centers. Particularly, the deviations of motility and motion kinematics were high according to the sample. Therefore, we suggest that it is necessary to develop a standard method for the cryopreservation of Korean native brindled cattle semen. We also suggest the need for sperm quality evaluation of the cryopreserved semen of Korean native brindled cattle before using artificial insemination to attain a high fertility rate.

Cryopreservation is used for blastocyst preservation of most mammalian embryos and is an important technique for breeding. We aimed to compare the efficiency of the cryopreservation method using the standard Cryotop device and the ReproCarrier device, a domestic product manufactured in Korea. The efficacy of the two devices was analyzed based on the survival rate, intracellular levels of reactive oxygen species (ROS), and apoptosis of the vitrified bovine blastocysts. The survival rates of the vitrified-warmed blastocysts were similar between the ReproCarrier group (58.4 ± 17.7%) and Cryotop group (59.9 ± 14.1%). Intracellular ROS levels and apoptotic index were determined by DCFDA staining and TUNEL assay. Changes in intracellular ROS levels, number of total nuclei, and cellular apoptosis of vitrified blastocysts after cryopreservation were not significantly different between the two groups. These results indicate that the ReproCarrier device method is as effective as the standard Cryotop method for vitrification of bovine blastocysts in vitro.

This study was conducted to find out the effect that κ-Carrageenan has on the properties of dog sperm when it was added to the cryoprotectant. Extender basically was contained 1.21 g Trizma base, 0.67 g citric acid, 0.4 g glucose, 0.03 g penicillin G, 0.05 g streptomycin sulfate. Extender1 was added with 0.1%, 0.2%, 0.3%, and 0.5% carrageenan, while extender2 was supplemented with glycerol. After freezing-thawing, the motility, viability, acrosome integrity, apoptosis, and ROS (reactive oxygen specifications) of sperm were measured to analyze the effects of the supplementation of carrageenan. Total Motile (TM), Rapid Progressive Motile (RPM), Medium Progressive Motile (MPM), and Immotile were measured through the CASA system after thawing in 37 degree water. Extender with 0.2% κ-carrageenan (64.26 ± 0.49) was significantly higher than control (40.24 ± 8.27) (p < 0.05). RPMs of extender with 0.1%, 0.2% κ-carrageenan (57.64 ± 6.34, 56.47 ± 1.35) were significantly higher than the other groups (p < 0.05). Acrosome integrity was measured by dyeing to PSA-FITC with an epifluorescence microscope. Normal acrosome ratio of extender with 0.5% κ-carrageenan (61 ± 8.03) was higher than the other groups (p < 0.05). Apoptosis was measured with a FACSCalibur flow cytometer using FITC (FITC Annexin V Apoptosis Detection Kit). Treated groups of κ-carrageenan of 0.1% (0.81 ± 0.05), 0.2% (0.85 ± 0.05) were significantly higer (p < 0.05) than control. Modified SYBR/PI staining was used for determination of viability and DCF staining was used for evaluation of ROS. Viability and ROS were not significantly different from other groups. In conclusion, adding a certain concentration of carrageenan to the extender of cryopreservation, carrageenan contributes to the improvement of the sperm motility, acrosome integrity and prevention of apoptosis.

Cryopreservation is mainly used for preservation of boar sperm. However, this method stresses the sperm by reactive oxygen species (ROS), and the conception rate and the litter size are not more efficient than the liquid preservation of spermatozoa. Therefore, we use chitosan which is a natural product derived antioxidant compound. We used GnHA (chitosan+hyaluronic acid) and GnHG (chitosan hydrogel) as chitosan complexes to cryopreserve boar sperm for improve sperm metabolism and function. Sperm parameter (sperm motility, progressive motility, path velocity, straight-line velocity, curvilinear velocity) is measured by computer-assisted sperm analysis (CASA) using frozen sperm with GnHA or GnHG (0, 0.25, 0.5, 1 mg/mL), respectively. Also, lipid peroxidation analysis using malondialdehyde (MDA) is performed to confirm the antioxidative effect of chitosan in frozen spermatozoa. CASA analysis showed GnHA and GnHG are effective against cryopreserved boar sperm. And antioxidant effect is measured by lipid peroxidation analysis. GnHA and GnHG, which is chitosan complex are effective for boar sperm cryopreservation by antioxidant effect.

The present study was undertaken to evaluate the effect of trisaccharides supplementation in glycerol-free tris (GFT) for the cryopreservation of dog spermatozoa. In the first experiment (E1), dog spermatozoa were resuspended with 50, 75, 100 or 125 mM of raffinose, melezitose or maltotriose and cooled at 4 ℃ for 10 min. To determine the effect of different cooling time, the spermatozoa resuspended with 100 mM of raffinose, melezitose or maltotriose were cooled during 10, 20, 30 or 40 min at 4 ℃ (second experiment; E2). The straws were then aligned horizontally for 10 min on the rack and then plunged into LN2. In the third experiment (E3), to determine the effect of different vapor freezing time, the spermatozoa resuspended with 100 mM raffinose were cooled at 4 ℃ for 20 min and frozen in LN2 for 5, 10, 15 or 20 min and then plunged into LN2. In the fourth experiment (E4), to compare different freezing methods [cooling plus vapor freezing (CV), cooling plus step-down freezing (CS) and direct step-down freezing (SD)], the spermatozoa resuspended with 100 mM raffinose were cooled for 20 min and frozen in LN2 vapor for 5 min in case of CV method. In case of CS method, spermatozoa were cooled for 20 min at 4℃ and then frozen by the step-down freezing method. The straws were then aligned horizontally at 18, 15, 5, and 2 cm respectively from the surface of LN2 for 1, 1, 1.4, and 5 min, respectively in an L shaped straw holder and then plunged into LN2. For SD method, the straws were directly aligned horizontally at the same levels as CS from the surface of LN2 for 1, 1, 1.9, and 5 min, respectively and then plunged into LN2. After thawing at 37℃ for 25 sec, the spermatozoa were then incubated for 30 min in the freezing extender (E1) or in the 50 mM sucrose supplemented GFT (E2, E3, and E4) at 24℃. Following post-thaw incubation, sperm progressive motility and viability were assessed in E1, E2, E3, and E4. In addition, acrosome integrity, and gene expression related to apoptosis (BAX, BCL2, and Caspase10) and sperm motility (SMCP) were evaluated in E4. The results demonstrated that, in E1, using 75 mM trisaccharides resulted in significantly (p<0.05) higher sperm motility in all sugar groups. Using 100 mM melezitose significantly (p<0.05) improved the post-thaw viability than the 100 mM raffinose. The viability in 100 mM maltotriose was similar with 100 mM raffinose and melezitose group. In E2, the different cooling time has no significant effect on post-thaw sperm progressive motility in all the sugar types. In addition, the viability was variable among the different groups. In E3, liquid nitrogen vapor freezing for 5 min resulted in improved motility and viability. The sperm progressive motility was significantly (p<0.05) higher in CV and SD group compared to CS group and the sperm viability was significantly (p<0.05) higher in CV group compared to the other groups in E4. However, the acrosomal integrity of spermatozoa in the group CV was significantly (p<0.05) higher than the group CS and SD. In addition, the expression of SMCP gene was significantly (p<0.05) higher in the CV group than the CS group. In contrast, the expression of Caspase10 significantly (p<0.05) lower in the group CV and SD than the group CS. Furthermore, the ratio of gene expression of BAX and BCL2 was significantly (p<0.05) lower in the group CV than the group CS. Therefore, cryopreservation of dog spermatozoa in 100 mM of raffinose supplemented GFT cooled for 20 min and vapor freezing for 5 min provides better progressive sperm motility, viability, and acrosome integrity with higher expression of SMCP gene and lower expression of caspase10 and BAX/BCL2 ratio following post-thaw incubation in 50 mM sucrose supplemented GFT for 30 min at 24℃.

The aim of this study was to develop a chemically defined extender for dog sperm cryopreservation by supplementation of essential and non-essential amino acids solution in EY-free PVA extender. Spermatozoa collected from mature dogs (1 ｘ 108 cell/ml) were frozen with EY-free extender supplemented with 0 (control), 1, 2, 4 % essential amino acids (EAAs) or 1, 2, 4 % non-essential amino acids (NEAAs). Sperm progressive motility, viability and acrosome integrity were evaluated immediately after thawing at 37 ℃ for 25 s and post-thaw incubation at room temperature for 20 min. In addition, to evaluate the synergistic effect of EAAs and NEAAs, spermatozoa were frozen with 0, 0.5, 1 or 2 % EAAs-NEAAs mixture (v:v). Sperm progressive motility, viability and acrosome integrity were evaluated immediately after thawing and post-thaw incubation. Additionally, spermatozoa were frozen using EY-free PVA extender supplemented with 2 % EAAs, 2 % NEAAs or 0.5 % EAAs-NEAAs mixture. The ROS level and phosphatidylserine (PS) translocation (Annexin V-FITC assay) were assessed using flow cytometry. In addition, gene expression level for SMCP (motility-related), apoptosis-related BCL2 and BAX was measured after freezing-thawing. The progressive motility of spermatozoa cryopreserved in EAAs or NEAAs significantly increased (P < 0.05) in all groups compared to the control group regardless of thawing conditions. In addition, 1 % NEAAs significantly protected the acrosome membrane of spermatozoa after freezing-thawing (P < 0.05). However, EAAs has shown no significant effect on viability and acrosome membrane integrity of spermatozoa. On the other hand, addition of EAAs-NEAAs mixture to EY-free PVA extender significantly (P < 0.05) increased sperm progressive motility without any effect on viability. Supplementation of 0.5 % EAAs-NEAAs mixture significantly (P < 0.05) increased the expression level of SMCP, BCL2 and BAX compared to control without significant effect on PS translocation and ROS level. We conclude that essential and non-essential amino acids solution can be effectively used in EY-free extender to improve sperm motility, acrosome integrity and gene expression of SMCP and BCL2 in dog sperm cryopreservation.

Cryopreservation is mainly used for preservation of boar sperm. However, this method stresses the sperm by reactive oxygen species (ROS), and the conception rate and the litter size are not more efficient than the liquid preservation of spermatozoa. Therefore, we use chitosan which is a natural product derived antioxidant compound. We used GnHA and GnHG as chitosan complexes to cryopreserve boar sperm for improve sperm metabolism and function. Sperm parameter (sperm motility, progressive motility, path velocity, straight-line velocity, curvilinear velocity) is measured by computer-assisted sperm analysis (CASA) using frozen sperm with GnHA or GnHG (0, 0.25, 0.5, 1 mg/mL). Also, lipid peroxidation analysis using malondialdehyde (MDA) is performed to confirm the antioxidative effect of chitosan in frozen spermatozoa. Sperm motility was higher in GnHA 0.25 mg/mL and GnHG 0.5 mg/mL compared to control. In addition, GnHG 0.5 mg/mL was significantly decreased in lipid peroxidation analysis. The results suggest that GnHA and GnHG are effective for boar sperm cryopreservation by antioxidant effect.

The aim of this study was performed to evaluate the effects of ice-binding protein from the arctic yeast Leucosporidium (LeIBP) supplementation on cryopreservation of boar sperm. The collected semen was diluted (1.5×108/ml) in lactose egg yolk (LEY) and cooled at 5°C for 3 h. The cooled semen was then diluted (1×108/ml) in LeIBP containing LEY with 9% glycerol and maintained at 5°C for 30 min. The semen was divided into six experimental groups (control, 0.001, 0.005, 0.01, 0.05 and 0.1 mg/ml of LeIBP). The straws were kept on above the liquid nitrogen (LN2) vapors for 20 minutes and then plunged into LN2. After thawing, computer-assisted sperm analysis was used for sperm motility and flow cytometry was performed to assess the viability, acrosome integrity (FITC-PSA/PI), ROS (DCF/PI), lipid peroxidation (BODIPY C11/PI) and apoptosis (Annexin V/PI), respectively. No significant responses were observed for sperm motility. However, sperm viability was significantly increased on 0.05 and 0.1 mg/ml of LeIBP groups compared to control (P < 0.05). In addition, acrosome integrity was significantly increases LeIBP groups (P < 0.05) and both ROS and lipid peroxidation level were lower in all LeIBP groups than those of control (P < 0.05). On the other hand, a significant higher apoptosis rate was observed in 0.05 and 0.1 mg/ml of LeIBP groups compared to control (P < 0.05). It can be assumed that a supplementation of LeIBP in boar sperm freezing extender is an effective method to increase the sperm qualities after cryopreservation.

Mesenchymal stem cells (MSCs), which are present in all tissues, can differentiate into cells with various specific functions. Recently, cell-based therapies using MSCs have been increasing in the veterinary research and related fields. In this study, we investigated the cellular morphology, proliferating capacities, expression of cell surface markers such as CD13, CD34, CD44, CD45, CD90, and CD105, mesodermal differentiation potentials, and expression of senescence-related markers of p53, p21, and telomerase reverse transcriptase in equine adipose tissue-derived MSCs (eAD-MSCs) after cryopreservation. The eAD-MSCs were analyzed immediately and after being frozen in liquid nitrogen for 1 year (< 1 year, G1) and more than 3 years (> 3 years, G2), respectively. After cryopreservation for 1 - 3 years, G2 eAD-MSCs showed similar cellular morphology, proliferating capacities, and expression of cell surface markers when compared with G1 eAD-MSCs. Moreover, cryopreservation did not affect the adipogenic, chondrogenic, or osteogenic differentiation potentials of G1 and G2 eAD-MSCs. Collectively, cryopreservation for (or over) 3 years maintained the stem cell phenotype and differentiation potentials of eAD-MSCs. These results will be an advantage that can be effectively used for future development of cell-based therapies.

Until today, success in germline cells and tissue cryopreservation is limited mainly due to the poor understanding of the complex physiological processes can lead to cell damage during cryopreservation. Germline cells, from both male and female, have unique ability to differentiate into one or more cell lines and thus it becomes a crucial point to store them in subzero temperature with the minimal damage of their functional properties and maximum recovery of unchanged and viable cells when thawed. In the past three decades, a vast research has been performed using various different animal models which in fact have led to development of new methodologies and optimization of older one. However, successful use of animal model has provided the opportunity in research with human germline cells and tissues preservation, but not in all the cases. Therefore, the use of new cryo-protective chemicals and modified protocols have been often found in different groups of researchers based on the types, physical structures, utility and animal species of the specimens to be cryopreserved. This review discusses about the basics of different types of cryopreservation methodologies and commonly used optimized protocols and cryoprotectants for germline cells and tissues preservation.

In the present study, we evaluated the effect of glucose-fructose and sucrose supplementation in glycerol-free tris (GFT) on sperm motility, viability, ROS level, apoptosis (BAX and BCL2) and motility (SMCP) related gene expression of dog sperm according to different post-thaw incubation time. The spermatozoa collected from five dogs were resuspended (5×107 cell/ml) with GFT containing 86 mM glucose and 86 mM fructose (GF-GFT) or 100 mM sucrose (S-GFT). The sperm (500 μl) were loaded in straws, cooled for 50 min at 4℃, frozen using liquid nitrogen (LN2) vapor for 20 min and plunged in LN2. The progressive motility, viability, ROS (H2O2) level and mRNA expression of spermatozoa were evaluated according to post-thaw incubation time (0 h, 3 h and 6 h) at 24℃. ROS was assessed using H2DCFDA stain by flow cytometry. The relative abundances of BAX, BCL2 and SMCP were assessed using quantitative real-time polymerase chain reaction (RT-PCR). The motility of spermatozoa cryopreserved in GF-GFT was increased throughout the post-thaw incubation time. The motility of spermatozoa cryopreserved in S-GFT was increased at 3 h of post-thaw incubation. Whereas, the sperm ROS level in GF-GFT group was decreased at 6 h of post-thaw incubation. However, the ROS level in the group S-GFT was gradually increased with the progress of post-thaw incubation period. The post-thaw incubation had no substantial effect on mRNA expression of BAX, BCL2 and SMCP genes of dog spermatozoa in both the GF-GFT and S-GFT groups. These results indicate that GF supplementation in GFT improves the progressive sperm motility during the 6 h of post-thaw incubation with maintaining similar sperm viability and is more efficient in reducing ROS after 3 h of post-thaw incubation. The addition of GF in GFT for the cryopreservation of dog spermatozoa and post-thaw incubation would open an option to achieve more functioning spermatozoa for future assisted reproduction practices.