Thermal Expansion of Cryoprotective Agents Combined with Synthetic Ice Blockers

描述（由申请人提供）：冷冻保存在组织库中的作用是无可争议的，是长期储存高质量生物材料的唯一实用替代方法。已经为许多细胞系统开发了成功的冷冻保存技术，但是外推到有组织的组织和器官充满了直到最近才开始解决的其他问题。这一点，再加上不断增长的需要冷冻库作为一种使能技术的组织工程和再生医学，产生了一个优先需要更大的控制额外的损伤机制负责大规模标本冷冻保存后恢复不良。主要的挑战围绕着避免冰形成（冷冻损伤的基石）和冷却和升温过程中产生的热机械应力造成的组织损伤，其中骨折形成是其最引人注目的结果。 随着最近有希望的结果，通过玻璃化（玻璃体在 拉丁语意思是玻璃状的），其中冰结晶被抑制，已被广泛认为是大规模冷冻保存的唯一选择。然而，通过玻璃化冷冻保存有其自身的困难，主要是由于与所需的高浓度冷冻保护剂（CPA）相关的毒性效应，以及由于促进玻璃化所需的高冷却速率而产生的高热机械应力。随着最近所谓的合成冰阻断剂（SIB）的应用，经由玻璃化的成功的大规模冷冻保存似乎比以往任何时候都更接近，其中CPA的浓度可以显著降低，并且实现玻璃化的临界冷却速率显著降低。然而，添加的SIB对发展的热机械应力的影响是未知的，其中CPA+SIB混合物的固体力学性质是未探索的。 探索SIB对低温保存鸡尾酒的热膨胀的影响是当前研究提案的主题，其中热膨胀是热机械应力的驱动机制。 具体而言，在这项研究中的目标是测量（第一次）选定的有前途的CPA+SIB鸡尾酒的热膨胀系数，并比较结果与先前建立的数据相同的CPA在没有SIB。此外，结果将被整合到选定的玻璃化过程的计算机模拟，以确定测量的属性值的意义。与此R21研究提案的探索性质相一致，本研究的结果将作为未来研究计划的基础，在大规模冷冻保存中应用SIB，以及它们对标本结构完整性的影响。 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可行的选择，有利于移植医学。目前建议的目的是探索最近发现的低温保护解决方案的热膨胀，其中热膨胀是大规模低温保存中断裂形成的驱动机制。测量的数据将被整合到计算机模拟中，并将用于预测特定低温保存方案中裂缝形成的可能性。

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.