The roles of reactive oxygen species and antioxidants in cryopreservation

Optimized addition of nitric oxide compounds in semen extender improves post-thaw seminal attributes of Murrah buffaloes

Semen dilution and cryopreservation alter the homogeneity of seminal plasma, resulting in a non-physiological redox milieu and consequently poor sperm functionality. Considering the concentration-specific bimodal action of nitric oxide (NO) in the regulation of sperm functions, cryopreservation media supplemented with optimized concentrations can improve the semen attributes. The present study aimed to evaluate the effect of adding an optimized concentration of sodium nitroprusside (SNP) and N-nitro-L-arginine methyl ester (L-NAME) in an extender on in vitro semen quality. An aliquot of semen samples (n = 32) from Murrah buffalo bulls (n = 8) was divided into control (C) and treatment (T-I: SNP in extender at 1 µmol/L; T-II: L-NAME in extender at 10 µmol/L). Fresh semen quality parameters showed no significant difference at 0 h except for the structural integrity in the T-II group. Post-thaw semen quality parameters and sperm kinematics using computer-aided sperm analysis (CASA) revealed significantly higher (p < 0.05) cryoresistance in the treatment groups. Viability, acrosome integrity, and membrane integrity were significantly higher (p < 0.05) in both treatment groups; however, the results were pervasive in T-II. Lower abnormal spermatozoa were observed in both T-I and T-II. SNP supplementation led to a significant rise (p < 0.05) in NO, whereas L-NAME reduced the NO concentration in post-thawed samples, which was directly correlated with different sperm functionality and associated biomarkers viz. total antioxidant capacity (TAC) and thiobarbituric acid reactive substance (TBARS). It was concluded that the cryopreservation media supplemented with SNP and L-NAME at 1 µmol/L and 10 µmol/L, respectively, lower the cryo-damage and improve post-thaw seminal attributes.

The Role of Promyelocytic Leukemia Zinc Finger (PLZF) and Glial-Derived Neurotrophic Factor Family Receptor Alpha 1 (GFRα1) in the Cryopreservation of Spermatogonia Stem Cells

The cryopreservation of spermatogonia stem cells (SSCs) has been widely used as an alternative treatment for infertility. However, cryopreservation itself induces cryoinjury due to oxidative and osmotic stress, leading to reduction in the survival rate and functionality of SSCs. Glial-derived neurotrophic factor family receptor alpha 1 (GFRα1) and promyelocytic leukemia zinc finger (PLZF) are expressed during the self-renewal and differentiation of SSCs, making them key tools for identifying the functionality of SSCs. To the best of our knowledge, the involvement of GFRα1 and PLZF in determining the functionality of SSCs after cryopreservation with therapeutic intervention is limited. Therefore, the purpose of this review is to determine the role of GFRα1 and PLZF as biomarkers for evaluating the functionality of SSCs in cryopreservation with therapeutic intervention. Therapeutic intervention, such as the use of antioxidants, and enhancement in cryopreservation protocols, such as cell encapsulation, cryoprotectant agents (CPA), and equilibrium of time and temperature increase the expression of GFRα1 and PLZF, resulting in maintaining the functionality of SSCs. In conclusion, GFRα1 and PLZF have the potential as biomarkers in cryopreservation with therapeutic intervention of SSCs to ensure the functionality of the stem cells.

Sperm cryopreservation: current status and future developments

The cryopreservation of spermatozoa is an important reproductive technology for the preservation of fertility in man and animals. Since the serendipitous discovery of glycerol as an effective cryoprotectant in 1947, sperm cryopreservation has undergone many changes in terms of the freezing methods employed, the rates at which samples are frozen and thawed, and the media used to preserve sperm functionality and DNA integrity. An extensive literature survey has been conducted addressing the cryoprotectants employed for both animal and human semen and the freezing protocols utilised. The results indicate that glycerol remains the dominant cryoprotective agent, usually incorporated into a balanced salt solution containing energy substrates, buffers, osmolytes and protein in the form of human serum albumin (human) or skimmed milk (animal). Realisation that some of the damage observed in cryostored cells involves the generation of reactive oxygen species during the thawing process, has prompted many studies to assess the relative merits of incorporating antioxidants into the cryopreservation media. However, in the absence of systematic comparisons, there is currently no consensus as to which antioxidant combination might be the most effective. Utilising our fundamental understanding of cryodamage to optimise cryopreservation protocols for each species will be important in the future.

Influence of the Addition of Zinc Oxide Nanoparticles to Cryopreservation Medium for Dog Epididymal Spermatozoa

The purpose of this study was to assess the effect of different concentrations of zinc oxide nanoparticles (ZnONPs) introduced to an extender for frozen-thawed epididymal dog spermatozoa. Epididymides from 22 castrated dogs were minced and cultured in a Tris buffer. The recovered spermatozoa were diluted in Tris-Citric acid-Fructose (TCF) extender with different concentrations of ZnONPs (100 and 200 µg/mL) and control (0.0 µg/mL). Diluted samples were equilibrated at 5 °C for 2 hours before being packed in 0.25 mL straws and stored in liquid nitrogen (-196 °C). After thawing at 37°C for 30 seconds, sperm motility, viability, membrane integrity, acrosome integrity, DNA integrity, and lipid peroxidation by malondialdehyde (MDA) concentration were all measured. The results were presented as mean ± SEM. Adding 100 and 200 µg/mL ZnONPs to the cryopreservation medium significantly (P < .05) improved motility and membrane integrity compared to the control. Viability and acrosome integrity were considerably (P < .05) better at 100 µg/mL ZnONPs than at 200 µg/mL ZnONPs and the control. MDA concentration was significantly (P < .05) decreased at 100 µg/mL ZnONPs compared to 200 µg/mL ZnONPs and the control. When 100 µg/mL ZnONPs were compared to 200 µg/mL ZnONPs and the control, the percentage of DNA damage was significantly (P < .05) reduced. Consequently, adding 100 µg/mL ZnONPs to TCF extender resulted in a significant increase in the proportion of motility, viability, membrane-intact, and acrosome-intact dog epididymal sperm, as well as the preservation of DNA integrity and the prevention of lipid peroxidation at the membrane level.

Glutathione and selenium nanoparticles have a synergistic protective effect during cryopreservation of bull semen

Introduction

In the present study, the synergistic protective effect of co-supplementation of glutathione (GSH) with selenium nanoparticles (SeNPs) on the cryopreservation efficiency of bull semen was analyzed.

Methods

After collection, the ejaculates of Holstein bulls were subsequently diluted with a Tris extender buffer supplemented with different concentrations of SeNPs (0, 1, 2, and 4 μg/ml), followed by semen equilibration at 4°C and assessment of sperm viability and motility. Subsequently, the ejaculates of Holstein bulls were pooled, split into four equal groups, and diluted with a Tris extender buffer supplemented with basic extender (negative control group, NC group), 2 μg/ml SeNPs (SeNPs group), 4 mM GSH (GSH group), and 4 mM GSH plus 2 μg/ml SeNPs (GSH + SeNPs group). After cryopreservation, motility, viability, mitochondrial activity, plasma membrane integrity, acrosome integrity, concentration of malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT), and ability of frozen-thawed sperm cells to support in vitro embryonic development were evaluated.

Results and discussion

No side effect of SeNPs concentrations applied in the current study on the motility and viability of equilibrated bull spermatozoa was found. Meanwhile, supplementation of SeNPs significantly promoted the motility and viability of equilibrated bull spermatozoa. Furthermore, the co-supplementation of GSH with SeNPs effectively protected bull spermatozoa from cryoinjury as expressed by promoting semen motility, viability, mitochondrial activity, plasma membrane integrity, and acrosome integrity. Finally, the enhanced antioxidant capacity and embryonic development potential in the frozen-thawed bull spermatozoa cryopreserved by co-supplementation of GSH with SeNPs further confirmed the synergistic protective effect of co-supplementation of GSH with SeNPs on the cryopreservation of bull semen.

Glutathione during Post-Thaw Recovery Culture Can Mitigate Deleterious Impact of Vitrification on Bovine Oocytes

Vitrification of bovine oocytes can impair subsequent embryo development mostly due to elevated oxidative stress. This study was aimed at examining whether glutathione, a known antioxidant, can improve further embryo development when added to devitrified oocytes for a short recovery period. Bovine in vitro matured oocytes were vitrified using an ultra-rapid cooling technique on electron microscopy grids. Following warming, the oocytes were incubated in the recovery medium containing glutathione (0, 1.5, or 5 mmol L^-1) for 3 h (post-warm recovery). Afterwards, the oocytes were lysed for measuring the total antioxidant capacity (TAC), activity of peroxidase, catalase and glutathione reductase, and ROS formation. The impact of vitrification on mitochondrial and lysosomal activities was also examined. Since glutathione, added at 5 mmol L^-1, significantly increased the TAC of warmed oocytes, in the next set of experiments this dose was applied for post-warm recovery of oocytes used for IVF. Glutathione in the recovery culture did not change the total blastocyst rate, while increased the proportion of faster developing blastocysts (Day 6-7), reduced the apoptotic cell ratio and reversed the harmful impact of vitrification on the actin cytoskeleton. These results suggest that even a short recovery culture with antioxidant(s) can improve the development of bovine devitrified oocytes.

Preclinical and Clinical Applications of Photobiomodulation Therapy in Sperm Motility: A Narrative Review

About 50% of infertility problems are related to male factors and reduced sperm motility. The important factor that affects the structure and function of sperm is reactive oxygen species (ROS), and over-concentration of ROS reduces the quality and motility of sperm. Photobiomodulation therapy (PBMT) using red to near-infrared (NIR) light is useful in oxidative stress restoration. It plays a therapeutic role in disorders such as asthenospermia, oligospermia cases, and cryopreserved sperm. It also enhances the metabolic capacity of sperm and increases the low-level and non-harmful intracellular content of Ca2+, nitric oxide (NO), and ROS in the stressed cells. Likewise, it modulates survival intracellular pathways and maintains the motility, viability, DNA, and acrosome integrity of sperm. This article reviews the state-of-the-art preclinical and clinical evidence regarding the efficacy of semen PBMT.

Oxidative Stress and Oocyte Cryopreservation: Recent Advances in Mitigation Strategies Involving Antioxidants

Oocyte cryopreservation is widely used in assisted-reproductive technology and animal production. However, cryopreservation not only induces a massive accumulation of reactive oxygen species (ROS) in oocytes, but also leads to oxidative-stress-inflicted damage to mitochondria and the endoplasmic reticulum. These stresses lead to damage to the spindle, DNA, proteins, and lipids, ultimately reducing the developmental potential of oocytes both in vitro and in vivo. Although oocytes can mitigate oxidative stress via intrinsic antioxidant systems, the formation of ribonucleoprotein granules, mitophagy, and the cryopreservation-inflicted oxidative damage cannot be completely eliminated. Therefore, exogenous antioxidants such as melatonin and resveratrol are widely used in oocyte cryopreservation to reduce oxidative damage through direct or indirect scavenging of ROS. In this review, we discuss analysis of various oxidative stresses induced by oocyte cryopreservation, the impact of antioxidants against oxidative damage, and their underlying mechanisms. We hope that this literature review can provide a reference for improving the efficiency of oocyte cryopreservation.

Abscisic acid induces the expression of AsKIN during the recovery period of garlic cryopreservation

Abscisic acid induced the expression of AsKIN during the recovery period of garlic cryopreservation. AsKIN was identified as a gene involved in cold and osmotic stress resistance. Cryopreservation has been proven to be effective in removing viruses from garlic. However, oxidative damage in cryopreservation has a significant impact on the survival after preservation. Abscisic acid (ABA) has been shown to reduce oxidative stress and promote the survival after cryopreservation. However, it is not clear which genes play important roles in this process. In this study, we added ABA to the dehydration step and analyzed the transcriptomic divergences between the ABA-treated group and the control group in three cryogenic steps (dehydration, unloading and recovery). By short time-series expression miner (STEM) analysis and weighted gene co-expression network analysis (WGCNA), the recovery step was identified as the period of significant changes in gene expression levels in cryopreservation. The addition of ABA promoted the upregulated expression of microtubule-related genes in the recovery step. We further identified AsKIN as a hub gene in the recovery step and verified its function. The results showed that overexpression of AsKIN enhanced the tolerance of Arabidopsis to oxidative stress in cryopreservation, influenced the expression of genes in response to cold and osmotic stress and promoted plant growth after stress. The AsKIN gene is likely to be involved in the plant response to cold stress and osmotic stress. These results reveal the molecular mechanisms of ABA in cryopreservation and elucidate the potential biological functions of the kinesin-14 subfamily.

Spirulina supplementation to the semen extender influences the quality and antioxidant parameters of chilled or cryopreserved Arabian stallion spermatozoa

The present study attempted to investigate the effect of various concentrations of spirulina platensis additions to the semen extender on Arabian stallion spermatozoa quality. Semen samples were collected with artificial vagina from five fertile stallions and diluted with an extender containing spirulina (2, 4, 6, and 8 mg/100 mL) or without spirulina (control). Aliquots of diluted semen were cooled (5°C, 90 min.) and frozen (-196°C, 7 d), then physical traits of thawed spermatozoa were examined. Furthermore, antioxidant activities of superoxide dismutase (SOD), glutathione reductase (GSR), total antioxidant capacity (TAC), and malondialdehyde (MDA) were measured in post-cooling and freezing spermatozoa. The results indicated that spirulina supplemented with the extender had no effect (P > 0.05) on sperm quality parameters and antioxidant activities after cooling. However, adding 6 mg spirulina/100 mL to the freezing extender improved (P < 0.05) the speed parameters and total motility percentage of frozen/thawed spermatozoa. Besides, supplementation of freezing extender with the previous level increased (P < 0.05) TAC, SOD and GSR concentrations/activities (0.86 ± 0.32 mM/L, 323.70 ± 12.81 U/mL, and 38.65 ± 1.90 U/mL, respectively) compared with the control (0.70 ± 0.25 mM/L, 165.80 ± 8.12 U/mL, and 25.70 ± 1.83 U/mL, respectively). While, lipid peroxidation of the frozen-thawed semen was reduced (P < 0.05, 17.97 ± 1.30 µmol/ L) compared with the control (29.39 ± 1.89 µmol/ L). Accordingly, the present results revealed that additions of 6 mg spirulina/100 mL to the freezing extender improved semen quality and reduced cryodamage of the Arabian stallion spermatozoa.

Long-term study on survival and development of successive generations of Mytilus galloprovincialis cryopreserved larvae

Shellfish aquaculture needs the development of new tools for the improvement of good practices avoiding the reliance on natural spat collection to increase production efficiently. The aim of this work was to improve the cryopreservation protocol for Mytilus galloprovincialis larvae described in Paredes et al. (in: Wolkers, Oldenhof (eds) Cryopreservation and freeze-drying protocol, methods in molecular biology, Humana Press, 2021, pp 2180, 10.1007/978-1-0716-0783-1_18). Moreover, the capability of producing adult mussels from cryopreserved 72 h-old D-larvae and potential long-term effects of cryopreservation through progenies were evaluated. The selection of 72-h old D-larvae for cryopreservation yielded 75% of recovery, higher than 50% from trochophores. The best combination was 10% Ethylene–Glycol + 0.4 M Trehalose in Filtered Sea Water (FSW) with cooling at − 1 °C/min and a water bath at 35 °C for thawing. Sucrose (SUC) solutions did not improve larval recovery (p > 0.05). At settlement, 5.26% of cryopreserved F1 larvae survived and over 70% settled. F2 cryopreservation produced 0.15% survival of spat and settlement varied from 35 to 50%. The delay of shell size showed on cryopreserved larvae declined throughout larval rearing without significant differences with controls from settlement point (p > 0.05). Long-term experiments showed that it is possible to obtain adult mussels from cryopreserved larvae and this tool does not compromise the quality of following progenies, neither for cryopreservation nor post-thawing development of them.

Antioxidant Effect of Melatonin on Proliferation, Apoptosis, and Oxidative Stress Variables in Frozen-Thawed Neonatal Mice Spermatogonial Stem Cells

Cryopreservation of spermatogonial stem cells (SSCs) is an important method to restore and maintain fertility in preadolescent children suffering from cancer. For protection of SSCs from cryoinjury, various antioxidant agents have been used. The aim of this study was to assess the antiapoptotic and antioxidant effects of melatonin in frozen-thawed SSCs. SSCs were isolated from testes of neonatal mice (3-6 days old) and their purities were measured by flow cytometry with promyelocytic leukemia zinc finger protein. After culturing, the cells were frozen in two groups (1) control and (2) melatonin (100 μM) and stored for 1 month. Finally, the cell viability, colonization rate, expression of Bcl-2 and BAX gene, and intracellular reactive oxygen species (ROS) were evaluated after freezing-thawing. Melatonin increased the viability and colonization of SSCs and Bcl-2 gene expression. It also diminished BAX gene expression and intracellular ROS. The results of this study show that melatonin with antioxidant and antiapoptotic effects can be used as an additive for freezing and long-term storage of cells and infertility treatment in the clinic.

Effectiveness of Clinical-Grade Chondroitin Sulfate and Ascorbic Acid in Mitigating Cryoprotectant Toxicity in Porcine Articular Cartilage

High concentrations of cryoprotective agents (CPAs) are required to achieve successful vitrification of articular cartilage; however, CPA cytotoxicity causes chondrocyte death. To reduce CPA toxicity, supplementation with research-grade additives, in particular chondroitin sulfate (CS) and ascorbic acid (AA), have previously been shown to improve chondrocyte recovery and metabolic function after exposure to CPAs at hypothermic conditions. However, it is necessary to evaluate the pharmaceutical equivalent clinical grade of these additives to facilitate the supplementation of additives into future vitrification protocols, which will be designed for vitrifying human articular cartilage in tissue banks. We sought to investigate the effectiveness of clinical-grade CS, AA, and N-acetylcysteine (NAC) in mitigating toxicity to chondrocytes during CPA exposure and removal, and determine whether a combination of two additives would further improve chondrocyte viability. We hypothesized that clinical-grade additives would exert chondroprotective effects comparable to those of research-grade additives, and that this protective effect would be enhanced if two additives were combined when compared with a single additive. The results indicated that both clinical-grade and research-grade additives significantly improved cell viability (p < 0.10) compared with the negative control (CPA with no additives). CS, AA, and NAC+AA increased cell viability significantly (p < 0.10) compared with the negative control. However, NAC, NAC+CS, and CS+AA did not improve cell viability when compared with the negative control (p > 0.10). We demonstrated that supplementation with clinical-grade CS or AA significantly improved chondrocyte viability in porcine cartilage subjected to high CPA concentrations, whereas supplementation with clinical-grade NAC did not benefit chondrocyte viability. Supplementation with clinical-grade additives in CPA solutions can mitigate CPA toxicity, which will be important in translating previously developed effective protocols for the vitrification of articular cartilage to human tissue banks.

Cryopreservation of porcine skin-derived stem cells using melatonin or trehalose maintains their ability to self-renew and differentiate

Porcine skin-derived stem cells (pSDSCs) are a type of adult stem cells (ASCs) that retain the ability to self-renew and differentiate. Currently, pSDSCs research has entered an intense period of development; however there has been no research regarding methods of cryopreservation. In this paper, we explored an efficient cryopreservation method for pSDSCs. Our results demonstrated that cryopreserving 50 μm diameter pSDSCs aggregates resulted in a lower apoptosis rate and a greater ability to proliferate to form larger spherical cell aggregates than during single-cell cryopreservation. To further optimize the cryopreservation method, we added different concentrations of melatonin (N-acetyl-5-methoxytryptamine, MLT) and trehalose (d-trehalose anhydrous, TRE) to act as cryoprotectants (CPAs) for the pSDSCs. After comparative experiments, we found that the cryopreservation efficiency of 50 mM TRE was superior. Further experiments demonstrated that the reason why 50 mM TRE improved cryopreservation efficiency was that it reduced the intracellular oxidative stress and mitochondrial damage caused by cryopreservation. Taken together, our results suggest that cryopreserving 50 μm diameter pSDSCs aggregates in F12 medium with 10% dimethyl sulfoxide (DMSO) and 50 mM TRE promotes the long-term storage of pSDSCs.

Tricine as a Novel Cryoprotectant with Osmotic Regulation, Ice Recrystallization Inhibition and Antioxidant Properties for Cryopreservation of Red Blood Cells

The cryopreservation of red blood cells (RBCs) plays a key role in blood transfusion therapy. Traditional cryoprotectants (CPAs) are mostly organic solvents and may cause side effects to RBCs, such as hemolysis and membrane damage. Therefore, it is necessary to find CPAs with a better performance and lower toxicity. Herein, we report for the first time that N-[Tri(hydroxymethyl)methyl]glycine (tricine) showed a great potential in the cryopreservation of sheep RBCs. The addition of tricine significantly increased the thawed RBCs’ recovery from 19.5 ± 1.8% to 81.2 ± 8.5%. The properties of thawed RBCs were also maintained normally. Through mathematical modeling analysis, tricine showed a great efficiency in cryopreservation. We found that tricine had a good osmotic regulation capacity, which could mitigate the dehydration of RBCs during cryopreservation. In addition, tricine inhibited ice recrystallization, thereby decreasing the mechanical damage from ice. Tricine could also reduce oxidative damage during freezing and thawing by scavenging reactive oxygen species (ROS) and maintaining the activities of endogenous antioxidant enzymes. This work is expected to open up a new path for the study of novel CPAs and promote the development of cryopreservation of RBCs.

Cryopreservation of Pig Semen Using a Quercetin-Supplemented Freezing Extender

Reactive oxygen species (ROS) produced during freeze−thaw procedures cause oxidative damage to the sperm, reducing fertility. We aimed to improve the post-thaw quality of pig sperm by quercetin (QRN) supplementation to reduce the cryodamage associated with the freeze−thaw procedure. Four equal aliquots of pooled boar semen were diluted with a freezing extender supplemented with different concentrations of QRN (0, 25, 50, and 100 µM) and then were subjected to cryopreservation in liquid nitrogen. Semen analysis was performed following 7 days of cryopreservation. Results demonstrated that the semen samples supplemented with 50 µM QRN significantly improved the post-thaw sperm quality than those subjected to other supplementations (p < 0.05). Semen samples supplemented with 50 µM QRN showed significantly improved plasma membrane functional integrity (47.5 ± 1.4 vs. 43.1 ± 4.1, 45.3 ± 1.7, and 44.1 ± 1.4) and acrosome integrity (73.6 ± 3.4 vs. 66.3 ± 2.4, 66.7 ± 3.6, and 68.3 ± 32.9) as compared to the control, 25 µM, and 100 µM QRN groups, respectively. The mitochondrial activity of the 50 µM QRN group was greater than control and 25 µM QRN groups (43.0 ± 1.0 vs. 39.1 ± 0.9 and 41.9 ± 1.0) but showed no difference with the 100 µM QRN group. Moreover, the 50 µM QRN group showed a higher sperm number displaced to 1 cm and 3 cm points in the artificial mucus than other groups. Therefore, supplementing the freezing extender with QRN can serve as an effective tool to reduce the magnitude of oxidative damage associated with sperm freezing.

Melatonin in cryopreservation media improves transplantation efficiency of frozen-thawed spermatogonial stem cells into testes of azoospermic mice

Background

Cryostorage of spermatogonial stem cells (SSCs) is an appropriate procedure for long-term storage of SSCs for fertility preservation. However, it causes damage to cellular structures through overproduction of ROS and oxidative stress. In this study, we examined the protective effect of melatonin as a potent antioxidant in the basic freezing medium to establish an optimal cryopreservation method for SSCs.

Methods

SSCs were obtained from the testes of neonatal male mice aged 3–6 days. Then, 100 μM melatonin was added to the basic freezing medium containing DMSO for cryopreservation of SSCs. Viability, apoptosis-related markers (BAX and BCL2), and intracellular ROS generation level were measured in frozen–thawed SSCs before transplantation using the MTT assay, immunocytochemistry, and flow cytometry, respectively. In addition, Western blotting and immunofluorescence were used to evaluate the expression of proliferation (PLZF and GFRα1) and differentiation (Stra8 and SCP3) proteins in frozen–thawed SSCs after transplantation into recipient testes.

Results

The data showed that adding melatonin to the cryopreservation medium markedly increased the viability and reduced intracellular ROS generation and apoptosis (by decreasing BAX and increasing BCL2) in the frozen–thawed SSCs (p < 0.05). The expression levels of proliferation (PLZF and GFRα1) and differentiation (Stra8 and SCP3) proteins and resumption of spermatogenesis from frozen–thawed SSCs followed the same pattern after transplantation.

Conclusions

The results of this study revealed that adding melatonin as an antioxidant to the cryopreservation medium containing DMSO could be a promising strategy for cryopreservation of SSCs to maintain fertility in prepubertal male children who suffer from cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03029-1.

Understanding and Comprehensive Evaluation of Cold Resistance in the Seedlings of Multiple Maize Genotypes

Maize is a cold-sensitive crop, and it exhibits severe retardation of growth and development when exposed to cold snaps during and right after seedling emergence. Although different agronomic, physiological, and molecular approaches have been tried to overcome the problems related to cold stress in recent years, the mechanisms causing cold resistance in maize are still unclear. Screening and breeding of varieties for cold resistance may be a sustainable option to boost maize production under low-temperature environments. Herein, seedlings of 39 different maize genotypes were treated under both 10 °C low temperature and 22 °C normal temperature conditions for 7 days, to assess the changes in seven growth parameters, two membrane characteristics, two reactive oxygen species (ROS) levels, and four antioxidant enzymes activities. The changes in ten photosynthetic performances, one osmotic substance accumulation, and three polyamines (PAs) metabolisms were also measured. Results indicated that significant differences among genotypes, temperature treatments, and their interactions were found in 29 studied traits, and cold–stressed seedlings were capable to enhance their cold resistance by maintaining high levels of membrane stability index (66.07%); antioxidant enzymes activities including the activity of superoxide dismutase (2.44 Unit g⁻¹ protein), peroxidase (1.65 Unit g⁻¹ protein), catalase (0.65 μM min⁻¹ g⁻¹ protein), and ascorbate peroxidase (5.45 μM min⁻¹ g⁻¹ protein); chlorophyll (Chl) content, i.e., Chl a (0.36 mg g⁻¹ FW) and Chl b (0.40 mg g⁻¹ FW); photosynthetic capacity such as net photosynthetic rate (5.52 μM m⁻² s⁻¹) and ribulose 1,5–biphosphate carboxylase activity (6.57 M m⁻² s⁻¹); PAs concentration, mainly putrescine (274.89 nM g⁻¹ FW), spermidine (52.69 nM g⁻¹ FW), and spermine (45.81 nM g⁻¹ FW), particularly under extended cold stress. Importantly, 16 traits can be good indicators for screening of cold–resistant genotypes of maize. Gene expression analysis showed that GRMZM2G059991, GRMZM2G089982, GRMZM2G088212, GRMZM2G396553, GRMZM2G120578, and GRMZM2G396856 involved in antioxidant enzymes activity and PAs metabolism, and these genes may be used for genetic modification to improve maize cold resistance. Moreover, seven strong cold–resistant genotypes were identified, and they can be used as parents in maize breeding programs to develop new varieties.

Antioxidant Activity and Oxidative Stress-Oriented Apoptosis Pathway in Saccharides Supplemented Cryopreserved Sperm of Pacific Abalone, Haliotis discus hannai

The Pacific abalone Haliotis discus hannai is a highly commercialized seafood in Southeast Asia. The aim of the present study was to determine the antioxidant activity and oxidative stress-oriented apoptosis pathway in saccharides supplemented cryopreserved sperm of Pacific abalone. Cryopreserved sperm showed impaired antioxidant defenses due to the reduced mRNA abundance of antioxidant genes (CAT, Cu/Zn-SOD, Mn-SOD, GPx, GR, and BCL-2), apoptosis inhibitor (HSP70, and HSP90) gene, and enzymatic antioxidant activity compared to fresh sperm. Such impaired antioxidant defenses caused an increase in the mRNA expression of apoptosis genes (Bax, and Caspase-3), finally leading to apoptosis. The impaired antioxidant defense also increased O₂^•− production and lipid peroxidation (MDA) levels, which further accelerated apoptosis. Considering all the experimental findings, an apoptosis pathway of cryopreserved sperm has been adopted for the first time. Specifically, sperm cryopreserved using 3% sucrose combined with 8% dimethyl sulfoxide (DMSO) showed improved mRNA stability, enzymatic activity, and DNA integrity with reduced O₂^•− production and MDA levels compared to sperm cryopreserved with the other types of examined cryoprotectants (8% ethylene glycol + 1% glucose, 6% propylene glycol + 2% glucose, 2% glycerol + 3% glucose, and 2% methanol + 4% trehalose). The present study suggests that 3% sucrose combined with 8% DMSO is suitable to cryopreserve the sperm of this valuable species for molecular conservation.

The Use of Quercetin to Improve the Antioxidant and Regenerative Properties of Frozen or Cryopreserved Human Amniotic Membrane

The biological properties of the human amniotic membrane (HAM) and its characteristic ability to be a reservoir of growth factors promoting wound healing make it an ideal biological dressing for the treatment of different clinical conditions, such as burns and non-healing wounds. However, the application of a preservation method on the HAM is required during banking to maintain biological tissue properties and to ensure the release overtime of protein content for its final clinical effectiveness after application on the wound bed. Although cryopreservation and freezing are methods widely used to maintain tissue properties, reactive oxygen species (ROS) are produced within tissue cellular components during their switching from frozen to thawed state. Consequently, these methods can lead to oxidative stress-induced cell injury, affecting tissue regenerative properties and its final clinical effectiveness. Taking advantage of the antioxidant activity of the natural compound quercetin, we used it to improve the antioxidant and regenerative properties of frozen or cryopreserved HAM tissues. In particular, we evaluated the oxidative damage (lipid peroxidation, malondialdehyde) as well as the regenerative/biological properties (bFGF growth factor release, wound healing closure, structure, and viability) of HAM tissue after its application. We identified the effectiveness of quercetin on both preservation methods to reduce oxidative damage, as well as its ability to enhance regenerative properties, while maintaining the unaltered structure and viability of HAM tissue. The use of quercetin described in this study appears able to counteract the side effects of cryopreservation and freezing methods related to oxidative stress, enhancing the regenerative properties of HAM. However, further investigations will need to be performed, starting from these promising results, to identify its beneficial effect when applied on burns or non-healing wounds.

Effect of addition of ascorbate, dithiothreitol or a caspase-3 inhibitor to cryopreservation medium on post-thaw survival of bovine embryos produced in vitro

Experiments were conducted to investigate whether supplementation of cryopreservation medium with ascorbate, dithiothreitol (DTT) or an inhibitor of caspase-3 (z-DEVD-fmk) could improve post-thaw survival of bovine embryos produced in vitro (IVP). For all experiments, embryos were harvested on day 7 after insemination and subjected to controlled-rate freezing in medium containing 1.5 M ethylene glycol and treatments as described below. In experiments 1-3, embryos were cryopreserved in freezing medium with ascorbate (0, 0.1, 0.3 or 0.5 mM), DTT (0, 50, 100 or 200 μM) and z-DEVD-fmk (0, 50, 100 or 200 μM), respectively. Post-thaw survival was assessed at 24, 48 and 72 h. For experiments 4-5, embryos were cryopreserved in freezing medium with or without 0.1 mM ascorbate. At 24 h post-thaw, embryo total cell number, DNA fragmentation and levels of reactive oxygen species (ROS) were evaluated. Embryos subjected to freezing and thawing in medium supplemented with 0.1 mM ascorbate had greater (p < .05) re-expansion rates at 24, 48 and 72 h and hatching rate at 72 h as compared to embryos not treated with ascorbate. Post-thaw cryosurvival was not affected by the addition of either DTT or z-DEVD-fmk to medium used for cryopreservation. Embryos cryopreserved in medium supplemented with 0.1 mM ascorbate had reduced (p < .001) levels of intracellular ROS and fewer (p < .001) cells with DNA fragmentation. In conclusion, post-thaw survival of bovine IVP embryos is enhanced by supplementation of freezing medium with ascorbate.

Exogenous Melatonin Ameliorates the Negative Effect of Osmotic Stress in Human and Bovine Ovarian Stromal Cells

Ovarian tissue cryopreservation transplantation (OTCT) is the most flexible option to preserve fertility in women and children with cancer. However, OTCT is associated with follicle loss and an accompanying short lifespan of the grafts. Cryopreservation-induced damage could be due to cryoprotective agent (CPA) toxicity and osmotic shock. Therefore, one way to avoid this damage is to maintain the cell volume within osmotic tolerance limits (OTLs). Here, we aimed to determine, for the first time, the OTLs of ovarian stromal cells (OSCs) and their relationship with reactive oxygen species (ROS) and mitochondrial respiratory chain activity (MRCA) of OSCs. We evaluated the effect of an optimal dose of melatonin on OTLs, viability, MRCA, ROS and total antioxidant capacity (TAC) of both human and bovine OSCs in plated and suspended cells. The OTLs of OSCs were between 200 and 375 mOsm/kg in bovine and between 150 and 500 mOsm/kg in human. Melatonin expands OTLs of OSCs. Furthermore, melatonin significantly reduced ROS and improved TAC, MRCA and viability. Due to the narrow osmotic window of OSCs, it is important to optimize the current protocols of OTCT to maintain enough alive stromal cells, which are necessary for follicle development and graft longevity. The addition of melatonin is a promising strategy for improved cryopreservation media.

Natural Cryoprotective and Cytoprotective Agents in Cryopreservation: A Focus on Melatonin

Cryoprotective and cytoprotective agents (Cytoprotective Agents) are fundamental components of the cryopreservation process. This review presents the essentials of the cryopreservation process by examining its drawbacks and the role of cytoprotective agents in protecting cell physiology. Natural cryoprotective and cytoprotective agents, such as antifreeze proteins, sugars and natural deep eutectic systems, have been compared with synthetic ones, addressing their mechanisms of action and efficacy of protection. The final part of this article focuses melatonin, a hormonal substance with antioxidant properties, and its emerging role as a cytoprotective agent for somatic cells and gametes, including ovarian tissue, spermatozoa and spermatogonial stem cells.

Ascorbic acid addition during dehydration improves garlic shoot tip cryopreservation but does not affect viral load

Cryopreservation is known be an effective method for virus elimination in garlic. However, oxidative damage during the cryopreservation seriously affects the survival of garlic after cryopreservation. Ascorbic acid (AsA) can reduce oxidative damage and improve regrowth following cryopreservation, and its effect may be influenced by the step during which it is added. In this study, AsA was added at the osmoprotection (O) and dehydration (DE) steps of cryopreservation. By observing the dynamic changes in cell viability and reactive oxygen species (ROS) components with different AsA treatments, AsA has been linked to the reduced accumulation of ROS in the shoot tips. Increased gene expression levels of antioxidant enzymes also explained the ROS scavenging effect of AsA. The correlation analysis between cell viability, ROS, membrane lipid peroxidation-related indicators and antioxidant-related indicators showed that membrane lipid peroxidation caused by excess ROS was the main factor affecting cell viability. Ascorbic acid added during dehydration minimized the accumulation of ROS from dehydration to dilution and alleviated the oxidative damage during cryopreservation. Thus, the survival and regrowth of the garlic was significantly improved after cryopreservation. Dehydration was found to be the suitable step for the addition of AsA during garlic cryopreservation. We further evaluated the virus elimination effect under optimal AsA treatment. However, there was no significant difference in virus content in regenerated plants when compared with the control.

Supplementation of Mito TEMPO and acetovanillone in semen extender improves freezability of buffalo spermatozoa

BACKGROUND

Oxidative stress is one of the leading factors responsible for poor post-thaw semen quality because of overproduction of reactive oxygen species (ROS) over neutralizing antioxidants present in semen. Mainly two ROS generation sites are present in spermatozoa, that is, mitochondria and plasma membrane. Therefore, the idea of targeting these specific sites for minimization of ROS production with the compounds having known mechanism of actions was built up as a core for this research.

OBJECTIVE

Present study was done to investigate the effects of Mito TEMPO and acetovanillone individually and in combination on freezability of buffalo spermatozoa.

MATERIALS AND METHODS

For the experiment, semen extender was supplemented with Mito TEMPO (50 μM), acetovanillone (50 μM), and a combination of Mito TEMPO + acetovanillone (50 μM+ 50 μM), designated as Group II, Group III, and Group IV, respectively. Control group without any supplementation was designated as Group I. A total of 24 ejaculates with individual progressive motility (IPM) of ≥70% were selected for the study. After final dilution, filling-sealing of straws, equilibration, and freezing were done as per the standard procedure. Semen samples were evaluated for IPM, plasma membrane integrity, lipid peroxidation, total antioxidant capacity (TAC), and cholesterol to phospholipids (C/P) ratio at both fresh and post-thaw stages. Evaluation of ROS, mitochondrial membrane potential (MMP), capacitation status (CTC assay), and in vitro fertility potential were conducted only on frozen-thawed samples.

RESULTS

The addition of Mito TEMPO (50 μM) and acetovanillone (50 μM) individually and in combination significantly (p < 0.05) improved post-thaw semen quality in terms of IPM, plasma membrane integrity, TAC, cholesterol content, C/P ratio, MMP, Chlortetracycline (CTC)-Full (F) pattern, and zona binding ability of buffalo spermatozoa, while significantly (p < 0.05) reduced ROS production, lipid peroxidation, and capacitation like changes as compared to the control group.

DISCUSSION

As Mito TEMPO acts as an SOD mimetic and also detoxifies ferrous iron at the mitochondria level, it aids in neutralization of excessive ROS production and minimizes oxidative stress-related damages that enhances the antioxidant potential of sperm mitochondria. Earlier studies also indicated improved post-thaw semen quality in 50 μM supplemented group. The improvement observed in acetovanillone (50 μM) group might be because of inhibition of Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase as this enzyme activation by various physical/chemical inducers during cryopreservation process leads to activation of CatSper channel resulting in calcium influx, premature capacitation, and acrosomal reaction like changes through activation of adenylate cyclase and cAMP/PKA-mediated tyrosine phosphorylation of sperm proteins. Acetovanillone also prevents NADPH oxidase-mediated inhibition of glutathione reductase activity, which has a vital role in protecting the structural and functional integrity of sperm plasma membrane.

CONCLUSION

Results indicated beneficial effects of supplementation of Mito TEMPO and acetovanillone on sperm freezability and individual supplementation was as efficient as the combination group for sustaining post-thaw semen quality.

Probe ultrasonification of egg yolk plasma forms low-density lipoprotein (LDL) nanoparticles that efficiently protect canine semen during cryofreezing

Around the world, many couples have turned to in vitro fertilization as a viable solution to fertility issues. Low-density lipoprotein (LDL) is a protein best known for transporting fat molecules throughout the body, but it has also been shown to protect sperm cells during cryopreservation due to its micellar structure. In the present study, we aimed to evaluate different protocols for the preparation of nanoparticles from egg yolk plasma (EYP) containing LDL to improve the viability of cryopreserved canine semen. EYP was subjected to three distinct treatments: ultrasonification in an ultrasound bath at 40 kHz for 30 min (LDL-B); ultrasonification via an ultrasound probe at 50% amplitude for 30 min (LDL-P); and high-pressure homogenization at 10,000 PSI for six cycles (LDL-H). Sperm quality was assessed after thawing using computer-assisted sperm analysis and flow cytometry. The results revealed that compared to the EYP control, the LDL-P formulation presented significantly higher efficiency (p < 0.05) in maintaining total and progressive sperm motility, sperm membrane integrity and fluidity, and levels of intracellular reactive oxygen species. The LDL-P nanoparticles had an average size of approximately 250 nm, a PDI value of 0.3, and −1.15 mV of zeta potential, which are very important because it is an indicator of the stability of a colloidal dispersion. Therefore, we conclude that ultrasonication of EYP using a probe is an efficient method for the preparation of LDL nanoparticles that would enhance the cryoprotection of semen during freezing.

Effects of Cryopreservation on Sperm with Cryodiluent in Viviparous Black Rockfish (Sebastes schlegelii)

Black rockfish is an economically important fish in East Asia. Little mention has been paid to the sperm cryopreservation in black rockfish. In this study, the optimal cryodiluent was selected from 48 combinations by detecting various sperm parameters. Transcriptome and methylome analysis were further performed to explore the molecular mechanism of inevitable cryoinjuries. The results showed that cryopreservation had negative effects on the viability, DNA integrity, mitochondrial activity, total ATPase and LDH of sperm even with optimal cryodiluent (FBS + 15% Gly). Transcriptome and methylome analysis revealed that the expression of 179 genes and methylation of 1266 genes were affected by cryopreservation. These genes were enriched in GO terms of death, G-protein coupled receptor signaling pathway, response to external stimulus and KEGG pathways of phospholipase D signaling pathway and xenobiotic and carbohydrate metabolism pathways. The role of PIK3CA and CCNA2 were highlighted in the protein-protein interaction network, and the sperm quality-related imprinted gene mest was identified among the 7 overlapping genes between transcriptome and methylome. Overall, the cryodiluent for black rockfish sperm was optimized, providing a feasible method for cryopreservation. The transcriptome and methylome data further demonstrated the underlying molecular mechanisms of cryoinjuries, proving clues for improvement of cryopreservation method of black rockfish.

The Protective Role of Melatonin in Sperm Cryopreservation of Farm Animals and Human: Lessons for Male Fish Cryopreservation

Simple Summary

In recent years, cryopreservation of fish sperm has been a rapidly evolving technique that contributes both to the improvement of genetic reproduction programs and the proper management of broodstock as well as to ensuring the viability of endangered species. However, this technique can cause significant damage to sperm, making the use of cryoprotectants and antioxidants in cryopreservation solutions imperative. The hormone melatonin has demonstrated positive effects on the cryopreservation of sperm in both farm animals and humans. Therefore, the plethora of research that has been conducted on animals and humans could be expanded to fish cryopreservation, making melatonin potentially a very promising alternative cryoprotectant.

Abstract

Cryopreservation is a technique that offers various advantages, especially in fish, among others, that makes the reproduction of species easier through a constant supply of sperm, synchronization of the gamete availability of both sexes, storage of semen for genetic improvement programs, reduction in the cost by eliminating the need to maintain male broodstock, and conserving the gametes of endangered species. However, freezing and warming procedures for cryopreservation lead to a reduction in the quality and viability of cryopreserved sperm because of oxidative stress. For this reason, the enrichment of extender media with antioxidants is a common method of cryopreservation of the semen of several fish species. Recently, many studies have been published for the protective role of antioxidants and especially of melatonin on male fertility preservation both in farm animals and humans, demonstrating the beneficial effects of melatonin as a sperm cryoprotectant. On the other hand, very few studies were conducted using melatonin as an antioxidant in different male fish species for semen cryopreservation. We conclude that the use of moderate concentrations of melatonin are beneficial to semen preservation, and the mechanisms through which melatonin acts positively on spermatozoa need to be further investigated to establish improvement protocols for cryopreservation in fish species.

Oxidative Stress and Assisted Reproduction: A Comprehensive Review of Its Pathophysiological Role and Strategies for Optimizing Embryo Culture Environment

Oxidative stress (OS) due to an imbalance between reactive oxygen species (ROS) and antioxidants has been established as an important factor that can negatively affect the outcomes of assisted reproductive techniques (ARTs). Excess ROS exert their pathological effects through damage to cellular lipids, organelles, and DNA, alteration of enzymatic function, and apoptosis. ROS can be produced intracellularly, from immature sperm, oocytes, and embryos. Additionally, several external factors may induce high ROS production in the ART setup, including atmospheric oxygen, CO2 incubators, consumables, visible light, temperature, humidity, volatile organic compounds, and culture media additives. Pathological amounts of ROS can also be generated during the cryopreservation-thawing process of gametes or embryos. Generally, these factors can act at any stage during ART, from gamete preparation to embryo development, till the blastocyst stage. In this review, we discuss the in vitro conditions and environmental factors responsible for the induction of OS in an ART setting. In addition, we describe the effects of OS on gametes and embryos. Furthermore, we highlight strategies to ameliorate the impact of OS during the whole human embryo culture period, from gametes to blastocyst stage.

The effect of testosterone and antioxidants nanoliposomes on gene expressions and sperm parameters in asthenospermic individuals

BACKGROUND

antioxidants that used for the infertility treatment cannot have their complete effectiveness, because of their instability in the culture medium.

SIGNIFICANCE

one of the most advances, in the drug delivery systems, is nanoliposomes-loaded, as biodegradable and bioavailable carriers. Hormonal and antioxidant agents encapsulating inside the nanoliposomes were used, to increase the effectiveness of antioxidants in the sperm culture medium.

MATERIALS

Semen sample from 15 asthenospermia were divided into 10 equal parts. After preparation, the sperms were incubated with free form of drugs and nanocarriers contained resveratrol, catalase, resveratrol-catalase and testosterone for 45 min. All sperm parameters, sperm DNA and gene expressions were evaluated before and after freezing.

RESULTS

Before freezing, all nanocarriers and free testosterone showed higher sperm motility compared to free drugs (P=.000). Free Testosterone and free resveratrol-catalase had higher DNA damage compared to nanocarriers (P=.000). Before freezing, the blank nanoliposome and testosterone nanoliposomes had the lowest HSP70 gene expression respectively (P = 0.005) (P = 0.001). After freezing, a significant reduction in sperm motility was observed in the free resveratrol-catalase group (P=.003). Also, a significant increase in sperm viability was observed in the free testosterone and nanoliposomes of blank and testosterone (P > 0.05). The least DNA damage was related to catalase nanoliposomes (P=.000). All nanoliposomes, especially catalase, had the highest percentage of class I morphology compared to the control group (P=.000).

CONCLUSIONS

Nanoliposomes could improve the sperm parameters and DNA integrity before and after freezing, by increasing the effectiveness of antioxidants. So, it can be recommended in the ART lab.

Aquaporins and Animal Gamete Cryopreservation: Advances and Future Challenges

Simple Summary

Cryopreservation is the method for the long-term preservation of gametes and embryos. In recent years, intensive research has focused on improving cryopreservation protocols for the determination of optimal freezing conditions and cryoprotective agents’ concentration for each cell type. The optimal cryopreservation protocol comprises the adequate balance between the freezing rate and the correct concentration of cryoprotective agents to achieve controlled cellular dehydration and minimal intracellular ice formation. Osmoregulation is, therefore, central in cryobiology. Water and some solutes can cross the plasma membrane, whereas facilitating transport takes a great part in intracellular/extracellular fluid homeostasis. Cells express water channels known as aquaporins that facilitate the transport of water and small uncharged solutes on their plasma membrane, including some cryoprotective agents. This review explores the expression and the function of aquaporins in gametes and embryos. In addition, the putative role of aquaporins for cryopreservation procedures is discussed.

Abstract

Cryopreservation is globally used as a method for long-term preservation, although freeze-thawing procedures may strongly impair the gamete function. The correct cryopreservation procedure is characterized by the balance between freezing rate and cryoprotective agents (CPAs), which minimizes cellular dehydration and intracellular ice formation. For this purpose, osmoregulation is a central process in cryopreservation. During cryopreservation, water and small solutes, including penetrating cryoprotective agents, cross the plasma membrane. Aquaporins (AQPs) constitute a family of channel proteins responsible for the transport of water, small solutes, and certain gases across biological membranes. Thirteen homologs of AQPs (AQP0-12) have been described. AQPs are widely distributed throughout the male and female reproductive systems, including the sperm and oocyte membrane. The composition of the male and female gamete membrane is of special interest for assisted reproductive techniques (ART), including cryopreservation. In this review, we detail the mechanisms involved in gamete cryopreservation, including the most used techniques and CPAs. In addition, the expression and function of AQPs in the male and female gametes are explored, highlighting the potential protective role of AQPs against damage induced during cryopreservation.

Cryopreservation and post-thaw characterization of dissociated human islet cells

The objective of this study is to optimize the cryopreservation of dissociated islet cells and obtain functional cells that can be used in single-cell transcriptome studies on the pathology and treatment of diabetes. Using an iterative graded freezing approach we obtained viable cells after cooling in 10% dimethyl sulfoxide and 6% hydroxyethyl starch at 1°C/min to -40°C, storage in liquid nitrogen, rapid thaw, and removal of cryoprotectants by serial dilution. The expression of epithelial cell adhesion molecule declined immediately after thaw, but recovered after overnight incubation, while that of an endocrine cell marker (HPi2) remained high after cryopreservation. Patch-clamp electrophysiology revealed differences in channel activities and exocytosis of various islet cell types; however, exocytotic responses, and the biophysical properties of voltage-gated Na+ and Ca2+ channels, are sustained after cryopreservation. Single-cell RNA sequencing indicates that overall transcriptome and crucial exocytosis genes are comparable between fresh and cryopreserved dispersed human islet cells. Thus, we report an optimized procedure for cryopreserving dispersed islet cells that maintained their membrane integrity, along with their molecular and functional phenotypes. Our findings will not only provide a ready source of cells for investigating cellular mechanisms in diabetes but also for bio-engineering pseudo-islets and islet sheets for modeling studies and potential transplant applications.

Regulation of Pdx1 by oxidative stress and Nrf2 in pancreatic beta-cells

The beta-cell identity gene, pancreatic duodenal homeobox 1 (Pdx1), plays critical roles in many aspects of the life of beta-cells including differentiation, maturation, function, survival and proliferation. High levels of reactive oxygen species (ROS) are extremely toxic to cells and especially to beta-cells due to their relatively low expression of antioxidant enzymes. One of the major mechanisms for beta-cell dysfunction in type-2 diabetes results from oxidative stress-dependent inhibition of PDX1 levels and function. ROS inhibits Pdx1 by reducing Pdx1 mRNA and protein levels, inhibiting PDX1 nuclear localization, and suppressing PDX1 coactivator complexes. The nuclear factor erythroid 2-related factor (Nrf2) antioxidant pathway controls the redox balance and allows the maintenance of high Pdx1 levels. Therefore, pharmacological activation of the Nrf2 pathway may alleviate diabetes by preserving Pdx1 levels.

Occurrence of heavy metals and their removal in Perna viridis mussels using chemical methods: a review

Despite the nutritional benefits, bivalves like mussels are also an excellent aquatic heavy metal biomonitoring agent due to their high tolerance to varying levels of temperature, salinity and oxygen, as well as pollutants. Although the accumulated toxic heavy metals may not exert direct negative impacts on the mussels, such toxicants in mussel tissues can give harmful effects on human body when consumed in toxic quantities and/or over prolonged period. The booming of urban and industrial activities, and consequently the increment of runoffs, as well as wastewater effluents and leaching, further exacerbated the magnitude of this issue. Hence, continuous monitoring of heavy metal contents in mussels is vital to ensure its compliance with food safety regulations, protecting consumers at large. This review paper discusses the occurrence of heavy metals in mussels especially that of Perna viridis in Malaysia and other parts of the world since year 2000 until 2021. Heavy metal concentration data and patterns from various coastal and/or estuaries were compared. Where applicable, statistical data that indicate variations between sampling sites, sampling months or years and chemical treatments for heavy metal removal were critically reviewed. Health risk assessment findings were also discussed. More importantly, related chemical-based interventions to minimize and/or eliminate toxic heavy metals from mussels are also reviewed.

Manufacturing T cells in hollow fiber membrane bioreactors changes their programming and enhances their potency

Engineered T cell therapies have revolutionized modern oncology, however processes for manufacturing T cell therapies vary and the impact of manufacturing processes On the cell product is poorly understood. Herein, we have used a commercially available hollow fiber membrane bioreactor (HFMBR) operated in a novel mode to demonstrate that T cells can be engineered with lentiviruses, grown to very high densities, and washed and harvested in a single, small volume bioreactor that is readily amenable to automation. Manufacturing within the HFMBR dramatically changed the programming of the T cells and yielded a product with greater therapeutic potency than T cells produced using the standard manual method. This change in programming was associated with increased resistance to cryopreservation, which is beneficial as T cell products are typically cryopreserved prior to administration to the patient. Transcriptional profiling of the T cells revealed a shift toward a glycolytic metabolism, which may protect cells from oxidative stress offering an explanation for the improved resistance to cryopreservation. This study reveals that the choice of bioreactor fundamentally impacts the engineered T cell product and must be carefully considered. Furthermore, these data challenge the premise that glycolytic metabolism is detrimental to T cell therapies.

Biomolecular Perturbations in In-Cell Dynamic Nuclear Polarization Experiments

In-cell DNP is a growing application of NMR to the study of biomolecular structure and function within intact cells. An important unresolved question for in-cell DNP spectroscopy is the integrity of cellular samples under the cryogenic conditions of DNP. Despite the rich literature around cryopreservation of cells in the fields of stem cell/embryonic cell therapeutics, cell line preservation and in cryo-EM applications, the effect of cryopreservation procedures on DNP parameters is unclear. In this report we investigate cell survival and apoptosis in the presence of cryopreserving agents and DNP radicals. We also assess the effects of these reagents on cellular enhancements. We show that the DNP radical AMUPol has no effect on membrane permeability and does not induce apoptosis. Furthermore, the standard aqueous glass forming reagent, comprised of 60/30/10 d₈-glycerol/D₂O/H₂O (DNP juice), rapidly dehydrates cells and induces apoptosis prior to freezing, reducing structural integrity of the sample prior to DNP analysis. Preservation with d₆-DMSO at 10% v/v provided similar DNP enhancements per √unit time compared to glycerol preservation with superior maintenance of cell size and membrane integrity prior to freezing. DMSO preservation also greatly enhanced post-thaw survival of cells slow-frozen at 1°C/min. We therefore demonstrate that in-cell DNP-NMR studies should be done with d₆-DMSO as cryoprotectant and raise important considerations for the progression of in-cell DNP-NMR towards the goal of high quality structural studies.

Metabolic activity in cryopreserved and grafted ovarian tissue using high-resolution respirometry

Cryopreservation of ovarian tissue followed by transplantation represents a strategy to restore ovarian function and fertility. Stress from cryopreservation-thawing processes can lead to alterations and/or damage to mitochondrial structure and functionality. High resolution respirometry and histological analysis were used to evaluate the effect of cryopreservation and transplantation on ovarian tissue. Four different conditions were performed: Fresh non-transplanted tissue, Fresh transplanted tissue, Cryopreserved non-transplanted tissue and Cryopreserved transplanted tissue. All groups were able to respond to the substrates-uncoupler-inhibitor protocol. We found a dramatic decrease in general oxygen consumption in hemi-ovaries submitted to cryopreservation and/or transplantation. The effect of cryopreservation on mitochondrial metabolism was less intense than effect of transplantation, since the transplantation affected all of the mitochondrial states. A total of 2644 follicles were analyzed. Of these, 2198 were classified as morphologically normal. The percentage of morphologically normal follicles was significantly lower in the Cryopreserved transplanted group when compared to the Cryopreserved non-transplanted group and the Fresh transplanted group (p-value < 0.05). Despite decreased follicular viability and mitochondrial activity, the cryopreservation followed by transplantation of ovarian tissue proved feasible for attempts to restore ovarian function.

Ex Situ Conservation and Genetic Rescue of Endangered Polish Cattle and Pig Breeds with the Aid of Modern Reproductive Biotechnology – A Review

The development and optimization of reproductive biotechnology – specifically semen cryopreservation, spermatological diagnostics, and intraspecies cloning by somatic cell nuclear transfer (SCNT) – have become essential techniques to conserve the genetic resources and establish genetic reserves of endangered or vanishing native Polish livestock breeds. Moreover, this biotechnology is necessary for perpetuating biological diversity and enhancing genetic variability as well as for restoring and reintroducing breeds into anthropogenic agricultural ecosystems. On the one hand, the purpose of our paper is to interpret recent efforts aimed at the ex situ conservation of native cattle and pig breeds. On the other, it emphasizes the prominent role played by the National Research Institute of Animal Production (NRIAP) in maintaining biodiversity in agricultural environmental niches. Furthermore, our paper provides an overview of the conventional and modern strategies of the banking and cryopreservation of germplasm-carrier biological materials and somatic cell lines, spermatological diagnostics, and semen-based and SCNT-mediated assisted reproductive technologies (ART s). These are the most reliable and powerful tools for ex situ protection of the genetic resources of endangered breeds of livestock, especially cattle and pigs.

Cryopreservation of Gametes and Embryos and Their Molecular Changes

The process of freezing cells or tissues and depositing them in liquid nitrogen at -196 °C is called cryopreservation. Sub-zero temperature is not a physiological condition for cells and water ice crystals represent the main problem since they induce cell death, principally in large cells like oocytes, which have a meiotic spindle that degenerates during this process. Significantly, cryopreservation represents an option for fertility preservation in patients who develop gonadal failure for any condition and those who want to freeze their germ cells for later use. The possibility of freezing sperm, oocytes, and embryos has been available for a long time, and in 1983 the first birth with thawed oocytes was achieved. From the mid-2000s forward, the use of egg vitrification through intracytoplasmic sperm injection has improved pregnancy rates. Births using assisted reproductive technologies (ART) have some adverse conditions and events. These risks could be associated with ART procedures or related to infertility. Cryopreservation generates changes in the epigenome of gametes and embryos, given that ART occurs when the epigenome is most vulnerable. Furthermore, cryoprotective agents induce alterations in the integrity of germ cells and embryos. Notably, cryopreservation extensively affects cell viability, generates proteomic profile changes, compromises crucial cellular functions, and alters sperm motility. This technique has been widely employed since the 1980s and there is a lack of knowledge about molecular changes. The emerging view is that molecular changes are associated with cryopreservation, affecting metabolism, cytoarchitecture, calcium homeostasis, epigenetic state, and cell survival, which compromise the fertilization in ART.

Supplementation of the freezing medium with Coenzyme Q10 attenuates oxidative stress and improves function of frozen-thawed giant grouper (Epinephelus lanceolatus) spermatozoa

Incorporation of Coenzyme Q10 (CoQ10) to the freezing medium provides advantageous effect for sperm cryopreservation in a variety of animal species, yet which has not been tested in giant grouper (Epinephelus lanceolatus). This research was designed to elucidate if CoQ10 could be used as a potential additive to improve giant grouper sperm quality after cryopreservation. After the process of freezing and thawing, various sperm quality parameters including motility, viability, apoptosis, mitochondrial membrane potential (MMP), intracellular reactive oxygen species (ROS) generation, DNA fragmentation as well as fertilization rate were evaluated with CoQ10 added at concentrations of 0, 25, 50 and 100 μM. Compared to the control group (0 μm), addition of CoQ10 in the medium yielded significantly higher total motility and curvilinear velocity, whereas the progressive motility, straight-line velocity and average path velocity were not differ from each other. An obvious improvement in viability was observed in spermatozoa cryopreserved with 25 and 50 μM CoQ10, while the apoptosis rate in CoQ10 treated groups (25, 50 and 100 μM) exhibited significantly lower values than that of the control. Besides, the production of ROS was significantly decreased with CoQ10 addition groups when compared with the control. In consistent with the improvement in antioxidant defense, CoQ10 supplementation in the medium also enhanced mitochondrial activity and reduced DNA fragmentation. In addition, freezing medium supplemented with CoQ10 also improved the fertilization success, a significantly higher fertilization rate was recorded at the concentration of 50 μM, but this value was not differ from that of 25 μM. Overall, the antioxidant CoQ10 provided an obvious beneficial effect on post-thaw quality of giant grouper spermatozoa. It was concluded that the optimal concentration of CoQ10 is 50 μM in the freezing medium.

Antioxidant Potential of the Bio-Based Fucose-Rich Polysaccharide FucoPol Supports Its Use in Oxidative Stress-Inducing Systems

Reactive oxygen species (ROS) are dangerous sources of macromolecular damage. While most derive from mitochondrial oxidative phosphorylation, their production can be triggered by exogenous stresses, surpassing the extinction capacity of intrinsic antioxidant defense systems of cells. Here, we report the antioxidant activity of FucoPol, a fucose-rich polyanionic polysaccharide produced by Enterobacter A47, containing ca. 17 wt% of negatively charged residues in its structure. Ferric reducing antioxidant power (FRAP) assays coupled to Hill binding kinetics fitting have shown FucoPol can neutralize ferricyanide and Fe3+-TPTZ species at an EC50 of 896 and 602 µg/mL, respectively, with positive binding cooperativity (2.52 ≤ H ≤ 4.85). This reducing power is greater than most polysaccharides reported. Moreover, an optimal 0.25% w/v FucoPol concentration shown previously to be cryo- and photoprotective was also demonstrated to protect Vero cells against H2O2-induced acute exposure not only by attenuating metabolic viability decay, but also by accentuating post-stress proliferation capacity, whilst preserving cell morphology. These results on antioxidant activity provide evidence for the biopolymer's ability to prevent positive feedback cascades of the radical-producing Fenton reaction. Ultimately, FucoPol provides a biotechnological alternative for implementation in cryopreservation, food supplementation, and photoprotective sunscreen formula design, as all fields benefit from an antioxidant functionality.

Photobiomodulation as an antioxidant substitute in post-thawing trauma of human stem cells from the apical papilla

Cryopreservation, the most common method of preserving stem cells, requires post-processing because it produces trauma to the cells. Post-thawing trauma typically induces cell death, elevates reactive oxygen species (ROS) concentration, and lowers mitochondrial membrane potential (MMP). Although this trauma has been solved using antioxidants, we attempted to use photobiomodulation (PBM) instead of chemical treatment. We used a 950-nm near-infrared LED to create a PBM device and chose a pulsed-wave mode of 30 Hz and a 30% duty cycle. Near-infrared radiation (NIR) at 950 nm was effective in reducing cell death caused by hydrogen peroxide induced-oxidative stress. Cryodamage also leads to apoptosis of cells, which can be avoided by irradiation at 950 nm NIR. Irradiation as post-processing for cryopreservation had an antioxidant effect that reduced both cellular and mitochondrial ROS. It also increased mitochondrial mass and activated mitochondrial activity, resulting in increased MMP, ATP generation, and increased cytochrome c oxidase activity. In addition, NIR increased alkaline phosphatase (ALP) activity, a biomarker of differentiation. As a result, we identified that 950 nm NIR PBM solves cryodamage in human stem cells from the apical papilla, indicating its potential as an alternative to antioxidants for treatment of post-thawing trauma, and further estimated its mechanism.

Elevated seminal protein carbonyl concentration is correlated with asthenozoospermia and affects adversely the laboratory intracytoplasmic sperm injection (ICSI) outcomes

Elevated concentrations of reactive oxygen species (ROS) in the semen can lead to oxidative protein damage as they react with the amino acids' side chains in the protein, leading to the generation of carbonyl groups. This study aimed to investigate the effect of protein carbonyl (PC) concentration on sperm motility and the laboratory intracytoplasmic sperm injection (ICSI) outcomes. A total of 150 couples from the ICSI cycle were enrolled in this study and were divided into three groups (G) according to the PC concentration as following, G1 included samples with PC concentrations <0.65 nmol/mg, G2 included samples with 0.65≤PC≤2.23 nmol/mg and G3 included samples with PC>2.23 (nmol/mg). PC concentrations were measured in all semen samples, and the laboratory ICSI outcomes were evaluated for all injected oocytes. The Kruskal-Wallis p-values for the differences in the medians of sperm motility, fertilisation rate, embryo cleavage score and embryo quality score were <0.05. Furthermore, Dunn's post hoc test showed a significant difference between all groups, p-values <0.05, except for the medians of embryo quality score between G2 and G3. In conclusion, our results showed that sperm motility and laboratory ICSI outcomes are affected negatively by higher concentrations of PC in the semen.

Aloe vera increases mRNA expression of antioxidant enzymes in cryopreserved bovine ovarian tissue and promotes follicular growth and survival after in vitro culture

The aims of the present study were to evaluate the effects of Aloe vera extract on expression of mRNA for antioxidant enzymes in bovine ovarian tissue after vitrification, as well as on follicular morphology, viability, activation and extracellular matrix in cultured ovarian tissues that had been previously vitrified. Fragments from bovine ovarian cortical tissue were cryopreserved in a vitrification solution alone or supplemented with two concentrations of Aloe vera (10 or 50%). After thawing, the cryopreserved tissues were analyzed by histological techniques, as well as the levels of mRNA for SOD, CAT, PRDX6 and GPX1 were investigated. Furthermore, cryopreserved fragments were then culture in vitro in α-MEM for 6 days. Histological evaluation of cultured tissues was performed to determine the percentages of normal and developing follicles. The results showed that, after vitrification, the presence of Aloe vera in both concentrations was able to maintain percentages of collagen fibers similar to fresh tissues (P < 0.05). Aloe vera in both concentrations significantly increased mRNA levels for PRDX6 and GPX1 in cryopreserved tissues, while 10% Aloe vera increased mRNA levels for SOD (P < 0.05). In parallel, after in vitro culture, fragments vitrified in the presence of 10% Aloe vera had significantly higher levels of morphologically healthy follicles when compared to tissue that were vitrified without Aloe vera. In fragments vitrified with Aloe vera, the rate of developing follicles was significantly higher than in tissues vitrified without Aloe vera. Tissues vitrified with 10% Aloe vera and cultured in vitro maintained percentages of collagen fibers similar to fresh tissues. In conclusion, 10% Aloe vera increases the expression of mRNA for PRDX6, GPX1 and SOD in vitrified ovarian tissues, maintains follicular survival and promotes activation and development of follicles after in vitro culture of vitrified bovine ovarian tissue.

Influence of helium, xenon, and other noble gases on cryopreservation of Hela and l929 cell lines

Any biological material contains dissolved gases that affect physical and biological processes associated with cooling and freezing. However, in the cryobiology literature, little attention has been paid to the effect of gasses on cryopreservation. We studied the influence of helium, neon, krypton, xenon, argon, nitrogen, and sulfur hexafluoride on the survivability of HeLa and L929 cell lines during cryopreservation. Saturation of a cell suspension with helium, neon, and sulfur hexafluoride enhanced survival of HeLa and L929 cells after cryopreservation. Helium exerted the most significant effect. For a range of noble gases, the efficiency of the positive effect decreased as the molecular mass of the gas increased. This paper discusses possible mechanisms for the influence of gases on the cryopreservation of biological material. The most probable mechanism is the disruption of the frozen solution structure with gas-filled microbubbles produced during water crystallization. Ultimately, it was concluded that helium and neon can be used to improve methods for cryopreservation of cell suspensions with a low concentration of conventional penetrating cryoprotectants or even without them.