Cryopreservation technologies represent a potential long term and minimally damaging method to preserve both native and engineered tissues. Conventional cryopreservation of allogeneic veins involving freezing is currently being used clinically, but in vivo studies using these grafts in both animal models and patients have demonstrated poor long-term patency rates. An alternative approach to cryopreservation involving vitrification that avoids the hazards of ice formation leads to a markedly improved vascular product in terms of both structure and function. Vitrification (vitreous means glassy in Latin) is essentially the solidification of a supercooled liquid by adjusting the chemical composition and cooling rate such that the crystal phase is avoided. This new preservation technology is now being scaled up for application to clinical specimens and ultimately engineered blood vessels. Nevertheless, additional hazards related to thermo-mechanical stresses in bulk vitrified specimens must be avoided for successful cryopreservation of tissues. Our long term goal is to reduce the destructive mechanical stresses induced during cryopreservation of tissues in general, and of blood vessels in particular. The purpose of this research is to develop engineering tools and to characterize the level of thermo-mechanical stresses in bulky cryopreserved tissues and thereby devise techniques to reduce, or circumvent, these stresses and develop improved methods of long term storage of both native and engineered vascular grafts.
The specific aims are to undertake a systematic study of thermo-mechanical stresses in cryopreserved blood vessels by measuring thermal expansion and stress-strain relationships. The measured parameters with appropriate mathematical modeling and computers simulations, will provide guidelines for minimizing the thermo-mechanical stresses and reduce the potential of fracture formation during cryopreservation. Although the experimental work in this study is targeted to blood vessels, the results of this study could be expanded and become useful for a wide variety of cryopreserved natural tissues and engineered constructs.
Showing the most recent 10 out of 15 publications
