Cryobiology最新文献

Cryopreservation in liquid nitrogen (LN) is an efficient long - term seed preservation strategy and water content is one of the main factors affecting seed viability after cryopreservation. In this study, Paeonia lactiflora seeds with varying water content were used as materials to determine changes in the antioxidant system before and after cryopreservation. When the water content of P. lactiflora seeds was 15.96 %-10.12 %, the viability of P. lactiflora seeds decreased significantly compared with that of the seeds without cryopreservation, but at the water content of 8.14 %-7.56 % there were no significant differences. However, when the water content of P. lactiflora seeds decreased to 6.01 %-5.19 % the viability was slightly increased compared to the seeds without cryopreservation. The content of superoxide anion (O₂^-), hydroxyl radical (·OH), hydrogen peroxide (H₂O₂), malondialdehyde (MDA) and protein carbonyl group (PCO) of seeds with high water content (15.96 %-10.12 %) were significantly increased after cryopreservation. However, superoxide anion (O₂^-), hydroxyl radical (·OH) and hydrogen peroxide (H₂O₂) did not change significantly in seeds with low water content (6.01 %-5.19 %) after cryopreservation, while oxidative stress indexes MDA and PCO decreased. These three substances were significantly negatively correlated with seed viability. In terms of antioxidant substances, the contents of catalase (CAT), ascorbic acid (AsA) and glutathione (GSH) decreased and the activities of glutathione reductase (GR) and dehydroascorbate reductase (DHAR) increased during the cryopreserved process of seeds with varying water content. These changes were significantly correlated with ROS content and the changes of MDA and PCO, among which AsA content, GSH content and CAT activity were positively correlated with seed viability. The changes of GR and DHAR activity were negatively correlated with seed viability. In summary, when the water content of the seeds ranged from 8.14 % to 5.19 %, ROS content did not increase significantly after cryopreservation compared with that of before preservation. The changes of MDA and PCO contents before and after cryopreservation, it was inferred that no obvious oxidative damage occurred in seeds, so the viability of seeds did not decrease compared with that of before cryopreservation. Therefore, the optimum water content of P. lactiflora seeds for cryopreservation is 8.14 %-5.19 %.

Nanocrystalline cerium dioxide is able to protect living cells from oxidative stress under the influence of various stress factors, in particular under the one of low temperatures. This study investigates the phase-structural transformations in aqueous solutions containing CeO₂ nanoparticles (NPs) and their impact on the cryopreservation process. Differential scanning calorimetry and thermomechanical analysis were used to analyse the phase transitions in aqueous suspensions of CeO₂ NPs and aqueous solutions of the cryoprotectant dimethyl sulfoxide (Me₂SO) with CeO₂ NPs. Various concentrations of CeO₂ NPs were tested to observe their effects on the crystallization and melting behaviours. The addition of CeO₂ NPs significantly altered the temperatures and enthalpies of melting and crystallization in water. Low concentrations of CeO₂ NPs promoted crystallization, while higher concentrations inhibited it, reducing supercooling and recrystallization during thawing. In Me₂SO solutions, CeO₂ NPs raised the glass transition temperature and affected the recrystallization process, with higher concentrations leading to more pronounced vitrification and reduced recrystallization. We also investigated the regularities of the effect of CeO₂ NPs on phase transitions in combined cryoprotective media with Ham's F12, fetal bovine serum and Me₂SO, which can be used in future to design the cryopreservation protocols. In the complex media, CeO₂ NPs decreased the metastability and altered eutectic crystallization patterns, indicating potential cryoprotective effects. In conclusion, CeO₂ NPs modulate the thermophysical properties of cryoprotective solutions, enhancing vitrification and reducing recrystallization, which could improve cryopreservation efficiency. Optimizing NP concentrations is crucial for practical applications in cryopreservation.

This study outlines a method for designing an isochoric (constant volume) system to reduce the supercooling preservation temperature without affecting the likelihood of ice nucleation and without the need for cryoprotective additives. The method involves a multiphase system wherein the biological material is separated from a second aqueous solution by a boundary that transfers pressure and heat but not mass. The pressure within the system is passively increased by the confined growth of ice within the secondary solution. This increased pressure in turn lowers the equilibrium freezing temperature of the biological matter, which may be utilized to lower the preservation temperature while maintaining the same degree of supercooling. For example, using this technique, the supercooling preservation temperature may be lowered from -2ºC to -5ºC without increasing the risk of ice nucleation, by ensuring the freezable phase makes up ∼17% of the total system volume.

We aimed to investigate the combined effects of alpha-lipoic acid (ALA) and sildenafil citrate (SC) on sperm quality during freeze-thawing in asthenozoospermic men. We categorized thirty semen samples from asthenozoospermic into five different groups for analysis: Control (fresh), Freeze, Freeze+SC, Freeze+ALA, and Freeze+SC+ALA. We evaluated sperm parameters in each group, including motility, viability, morphology, plasma membrane integrity, DNA fragmentation, mitochondrial membrane potential, protamine deficiency, acrosome integrity, malondialdehyde, tumor necrosis factor-alpha (TNF-α), antioxidants (Superoxide dismutase, Glutathione, Catalase), and gene expression of HSP70 and Bcl-2. The Freeze group showed significant declines in viability, motility, morphology, membrane integrity, antioxidants, and mitochondrial membrane potential, with increases in protamine deficiency, abnormalities, DNA fragmentation, TNF-α, and malondialdehyde compared to control (p=0.000). These effects were significantly reversed in all treatment groups (p=0.000). Bcl-2 and HSP70 expression increased significantly in all groups (p=0.000). Acrosomal integrity decreased significantly (p=0.000) in the Freeze group compared to controls and in the Freeze+SC group compared to the Freeze group. However, acrosomal integrity significantly increased (p=0.000) in the Freeze+SC+ALA group compared to the Freeze+SC group and in the Freeze+ALA group compared to other treatments. Our findings indicate that the simultaneous addition of SC and ALA in the freezing media yielded increased sperm quality. This enhancement was evidenced by reductions in oxidative stress, inflammation, and apoptosis, along with partial prevention of premature acrosome reactions induced by SC.

Spermatogonia cryopreservation is a method to preserve valuable genomes from both maternal and paternal origin. The damage associated with the application of this technology on post-thaw cell quality is important to assess, including at the epigenetic level. This study aimed to assess post-thawed spermatogonia quality by evaluating alterations in plasma membrane integrity, DNA integrity (fragmentation and apoptosis), lipid peroxidation (malondialdehyde levels) and epigenetic modifications (DNA methylation profile). We observed that plasma membrane integrity (fresh 78.98% ± 5.66; cryopreserved 62.81% ± 3.25; P = 0.003) and DNA integrity (fresh 32.95% ± 2.28; cryopreserved 37.28% ± 1.87; P = 0.0026) were affected by cryopreservation, while no difference in lipid peroxidation was observed (fresh 1.13% ± 0.45; cryopreserved 0.91% ± 0.96; P = 0.701). While global levels of DNA methylation were unaffected by cryopreservation (fresh 82.80% ± 0.47; cryopreserved 83.32% ± 0.81; P = 0.745), some differentially methylated cytosines (DMC) were observed in cryopreserved versus fresh spermatogonia (156 DMC). This study showed that spermatogonia cryopreserved according to our protocol provides a good supply of undamaged cells for several applications. The significance of the few detected DMCs deserves further attention since it may affect gamete differentiation and epigenetic profile.