Thermal Expansion of Cryoprotective Agents Combined with Synthetic Ice Blockers

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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.