Studies on the mechanisms of XXXX cell killing by a freeze-thaw cycle: conditions that prevent cell killing using nucleated freezing.

@entity1 @entity7970 @entity137 @entity1735 @entity3733 @entity653 @entity969 @entity413
Normally a freeze-thaw cycle is a very efficient method of killing @entity1 cells. However, this report describes conditions that prevent killing of cultured @entity1 cells by nucleated freezing at -24 degrees C. Optimal protection from cell killing at -24 degrees C was obtained in isotonic solutions containing an organic cryoprotectant such as @entity3733 ( @entity3733 ; 10%, v/v), a @entity1735 such as @entity969 over a broad concentration range from 50 to 150 mM, and @entity413 . @entity653 was also an effective cryoprotectant but other organic solvents were ineffective, although in some cases they appeared to protect cell membranes, while not protecting other vital components. A wide variety of @entity1735 structures were effective at protecting cells from freeze-thaw killing, with @entity7970 being particularly effective. The degree of resistance to killing by a freeze-thaw cycle under these conditions varied widely among different cell lines. If @entity137 of @entity3733 was responsible for this variability of cryoprotection, it must have been due to short-term, not longer term, @entity137 of @entity3733 . Studies on the mechanism by which cells are protected from killing under these conditions indicated that neither vitrification of the medium nor the concentrating of components during freezing were involved. One model not eliminated by the mechanistic studies proposes that the organic solvent cryoprotectant component acts by fluidizing membranes under the thawing conditions, so that any holes produced by ice crystals propagating through membranes can reseal during the thawing process. In this model one of the mechanisms by which the @entity1735 component could act is by entering the cells and stabilizing vital intracellular components. Consistent with this, a freeze-thaw cycle promoted the uptake of labeled @entity969 into cultured cells.
