Abstract
To assess the viability of vitrified biological tissue by measurement of the effective thermal diffusivity (ETD), intracellular ETD was estimated. Human fibroblasts were cultured at 10^6 and 10^7 cells/cm^3 for 2 days in a collagen sponge (φ20×1 mm) to prepare artificial tissue. The artificial tissue was frozen at cooling rates of 200 to 800℃/min from 4 to -196℃ in culture medium containing with 35wt% propylene glycol. The temperature of the artificial tissue was increased stepwise from -190 to -185℃ ; the ETD was determined by using a Laplace transform method. Post-thaw viability was evaluated by using a trypan blue exclusion assay. Intracellular ETD was estimated by a Maxwell-Eucken equation. As a result, estimated ETD was higher than extracellular ETD, and decreased with increasing the cooling rate.
