Micro-behavior and Viability of Biological Cell During Freezing

Abstract

The accurate prediction of viability after freezing of biologial cell is greatly important for determining proper handling in cryopreservation. In this paper, linking between microscale behavior and viability of cell during reciprocal freezing-thawing has been studied. As a sample of biological cell, protoplasts isolated from cultured wheat cells were used. As the results of microscopic observation using cryostage whose cooling and heating rates were controlled, the contraction of cell by water efflux due to osmotic pressure difference and intracellular ice formation under supercooling stage were clarified with the cooling rate. Next, the reciprocal contraction-recovery of the cell during freezing-thawing was realized by osmotic manipulations in in vitro experiments. It was found that the dehydration fraction of cell is available parameter to indicate the degree of damage due to solution effects. Summarizing these results, the viability of cell was quantitatively estimated by considering the injury due to solution effects and intracellular ice formation.