ASSESSMENT OF CELLULAR DAMAGE DURING COOLING TO -196-DEGREES-C USING RADIOCHEMICAL MARKERS

The release of ten radiochemical markers from MRC-5 and CHO cells after cooling at various rates and thawing from temperatures in the range of 0 to -196 °C was measured. Many of these radiochemicals had specific sites of attachment on or within the cell and the aim was to determine the effect of freeze-thaw stresses on various parts of the cell. Cell death during cooling and thawing was, in most instances, accompanied by osmotic damage and loss of cytoplasmic constituents. Significant damage to the cell membrane occurred only after the cell was already dead and was related to the disruption of cells killed at higher temperatures and to osmotic stress during rewarming. The release of cations and other cytoplasmic markers was correlated to cell shrinkage and dehydration. The data were used to assess the relative effects of some of the proposed damaging factors in freeze-thaw injury (thermal shock, ice damage, dilution shock, etc.). CHO cells showed a much higher survival rate and release of cations after fast cooling than MRC-5 cells. This, and additional circumstantial information, indicated that CHO cells survived freeze-thaw cycles better than MRC-5 cells because they are able to dehydrate more readily, even at fast cooling rates. © 1978.