Thermal Expansion of Cryoprotective Agents Combined with Synthetic Ice Blockers

描述(申请人提供)：低温保存在组织库中的作用是毋庸置疑的，是长期储存高质量生物材料的唯一实用选择。已经为许多细胞系统开发了成功的冷冻保存技术，但外推到有组织的组织和器官充满了额外的问题，这些问题直到最近才开始解决。这一点，加上作为组织工程和再生医学的一种使能技术的冷冻库的需求日益增长，已经产生了优先需要更好地控制导致大规模标本在低温保存后恢复不佳的额外损伤机制的需要。主要的挑战围绕着避免冰层形成(低温损伤的基石)和在降温和升温过程中产生的热机械应力对组织造成损害，骨折的形成是最戏剧性的结果。随着最近有希望的结果，玻璃化冷冻保存的应用(玻璃化在 拉丁语的意思是玻璃)，其中冰的结晶被抑制，已被广泛认为是大规模冷冻保存的唯一选择。然而，通过玻璃化方法进行低温保存有其自身的困难，主要是由于与所需高浓度低温保护剂(CPA)相关的毒性效应，以及由于促进玻璃化所需的高冷却速度而产生的高热机械应力。随着合成阻冰剂(SIB)的应用，成功的大规模玻璃化冷冻保存似乎比以往任何时候都更接近成功，可以显著降低CPA的浓度，显著降低实现玻璃化冷冻的临界冷却速度。然而，添加SIB对发展的热机械应力的影响尚不清楚，其中CPA+SIB鸡尾酒的固体力学性质还没有被探索。探索SIB对低温保存鸡尾酒热膨胀的影响是当前研究方案的主题，其中热膨胀是热机械应力的驱动机制。具体地说，这项研究的目的是(首次)测量选定的有希望的CPA+SIB鸡尾酒的热膨胀系数，并将结果与以前在没有SIB的情况下对相同CPA的数据进行比较。此外，结果将被整合到选定的玻璃化过程的计算机模拟中，以确定测量的属性值的重要性。与R21研究计划的探索性一致，这项研究的结果将作为未来SIB在大规模冷冻保存中的应用及其对标本结构完整性影响的研究计划的基础。 公共卫生相关性：冷冻保存是长期储存高质量生物材料的唯一实际替代方案，有利于移植医学。目前这项提议的目的是探索最近发现的低温保护性溶液的热膨胀，其中热膨胀是大规模低温保存中裂缝形成的驱动机制。测量的数据将被整合到计算机模拟中，并将用于预测特定冷冻保存方案中骨折形成的可能性。

DESCRIPTION (provided by applicant): The role of cryopreservation for tissue banking is undisputable, being the only practical alternative for long-term storage of high quality biomaterial. Successful techniques for cryopreservation have been developed for many cellular systems, but extrapolation to organized tissues and organs is fraught with additional problems that have only recently begun to be addressed. This, coupled with the growing need for cryobanking as an enabling technology for tissue engineering and regenerative medicine, has generated a priority need for a greater control of the additional mechanisms of injury responsible for the poor recovery of large-scale specimens after cryopreservation. The principal challenges revolve around avoiding tissue damage from ice formation (the cornerstone of cryoinjury) and from the thermo-mechanical stress generated during cooling and warming, with fracture formation as its most dramatic outcome. With recent promising results, the application of cryopreservation by means of vitrification (vitreous in Latin means glassy), where ice crystallization is suppressed, has become widely recognized as the only alternative for large-scale cryopreservation. However, cryopreservation by means of vitrification has its own difficulties, essentially resulting from toxicity effects associated with the high concentration of cryoprotective agents (CPAs) needed, and from the high thermo-mechanical stresses generated due to the high cooling rates required to promote vitrification. With the recent application of the so-called synthetic ice blockers (SIBs), successful large-scale cryopreservation via vitrification appears closer than ever before, where the concentration of the CPA can be significantly reduced, and the critical cooling rate to achieve vitrification is significantly lowered. However, the effect of the added SIBs on the developing thermo-mechanical stress is yet unknown, where the solid mechanics properties of the CPA+SIB cocktail are unexplored. Exploring the effects of SIBs on thermal expansion of the cryopreservation cocktail is the subject matter of the current research proposal, where thermal expansion is the driving mechanism of thermo-mechanical stress. Specifically, the objective in this study is to measure (for the first time) the thermal expansion coefficients of selected promising CPA+SIB cocktails, and compare the results with previously established data on the same CPAs in the absence of SIBs. In addition, results will be integrated into computer simulations of selected vitrification processes, to identify the significance of the measured property values. Consistent with the exploratory nature of this R21 research proposal, results of this study will serve as the foundation for a future research program on the application of SIBs in large-scale cryopreservation, and their effects on the structural integrity of the specimen. PUBLIC HEALTH RELEVANCE: Cryopreservation is the only practical alternative for long-term storage of high quality biomaterial for the benefit of transplantation medicine. The objective of the current proposal is to explore the thermal expansion of recently discovered cryoprotective solutions, where thermal expansion is the driving mechanism of fracture formation in large-scale cryopreservation. The measured data will be integrated into computer simulations and will be used to predict the likelihood of fracture formation in specific cryopreservation protocols.