title: Stress-strain measurements and viscoelastic response of blood vessels cryopreserved by vitrification.
abstract: To gain increased insight into thermo-mechanical phenomena during cryopreservation, tensile stress relaxation experiments were conducted on vitrified blood vessels (vitreous in Latin means Glassy), and the results compared with various viscoelastic models. Using a recently presented device, isothermal stress-relaxation results were obtained for a bovine carotid artery model, permeated with the cryoprotectant cocktail VS55 and a reference solution of 7.05 M DMSO. After a rapidly applied tensile strain, experimental results display exponential decay of stress with time; the stress at a given time increases with decreasing specimen temperature. Among the viscoelastic models investigated, the Williams-Landel-Ferry model was found to best-fit the variation of the stress relaxation data with temperature, while a Maxwell-Weichert model is used to represent the exponential decay of the stress with time. Blood vessel properties were found to dominate at temperatures above roughly -100 degrees C, while the properties of the cryoprotectant dominate below this temperature. A suitably defined steady-state viscosity displayed a similar behavior for both cryoprotectants, when normalized with respect to the cryoprotectant glass transition temperature.
authors.affiliation: Biothermal Technology Laboratory, Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA. rabin@cmu.edu
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Jimenez Rios
authors.forename: Paul S
authors.initials: PS
authors.lastname: Steif
authors.forename: Yoed
authors.initials: Y
authors.lastname: Rabin
mesh_terms: D000818:Animals; D016880:Anisotropy; D001696:Biomechanical Phenomena / Q000379:methods*; D002339:Carotid Arteries / Q000502:physiology*; D002417:Cattle; D003198:Computer Simulation; D015925:Cryopreservation / Q000379:methods*; D004548:Elasticity; D066298:In Vitro Techniques; D008955:Models, Cardiovascular; D013314:Stress, Mechanical; D014021:Tissue Preservation / Q000379:methods*; D014783:Viscosity