Low temperatures slow or halt undesired biological and chemical processes, protecting cells, tissues, and organs during storage. Cryopreservation techniques, including controlled media exchange and regulated freezing conditions, aim to mitigate the physical consequences of freezing. Dimethyl sulfoxide (DMSO), for example, is a penetrating cryoprotecting agent (CPA) that minimizes ice crystal growth by replacing intracellular water, while polyvinyl alcohol (PVA) is a nonpenetrating CPA that prevents recrystallization during thawing. Since proteins and ground substance dominate the passive properties of soft biological tissues, we studied how different freezing rates, storage temperatures, storage durations, and the presence of cryoprotecting agents (5% [v/v] DMSO + 1 mg/mL PVA) impact the histomechanical properties of the internal thoracic artery (ITA), a clinically relevant blood vessel with both elastic and muscular characteristics. Remarkably, biaxial mechanical analyses failed to reveal significant differences among the ten groups tested, suggesting that mechanical properties are virtually independent of the cryopreservation technique. Scanning electron microscopy revealed minor CPA-independent delamination in rapidly frozen samples, while cryoprotected ITAs had better post-thaw viability than their unprotected counterparts using methyl thiazole-tetrazolium (MTT) metabolic assays, especially when frozen at a controlled rate. These results can be used to inform ongoing and future studies in vascular engineering, physiology, and mechanics.

中文翻译：

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冷冻保存对弹肌动脉力学的影响

低温会减缓或停止不需要的生物和化学过程，从而在储存过程中保护细胞、组织和器官。冷冻保存技术，包括受控介质交换和受控冷冻条件，旨在减轻冷冻的物理后果。例如，二甲亚砜 (DMSO) 是一种渗透性冷冻保护剂 (CPA)，可通过替换细胞内的水来最大限度地减少冰晶的生长，而聚乙烯醇 (PVA) 是一种非渗透性 CPA，可防止解冻过程中的重结晶。由于蛋白质和基质主导着软生物组织的被动特性，我们研究了不同的冷冻速率、储存温度、储存持续时间以及冷冻保护剂（5% [v/v] DMSO + 1 mg/mL PVA）的存在如何影响胸廓内动脉 (ITA) 的组织力学特性，这是一种具有弹性和肌肉特征的临床相关血管。值得注意的是，双轴机械分析未能揭示十组测试之间的显着差异，这表明机械性能实际上独立于冷冻保存技术。扫描电子显微镜显示快速冷冻样品中存在轻微的与 CPA 无关的分层，而使用甲基噻唑-四唑 (MTT) 代谢测定，冷冻保护的 ITA 比未受保护的 ITA 具有更好的解冻后活力，特别是在以受控速率冷冻时。这些结果可用于为血管工程、生理学和力学领域正在进行和未来的研究提供信息。