Genetic damage is not produced by normal cryopreservation procedures involving either glycerol or dimethyl sulfoxide: a cautionary note, however, on possible effects of dimethyl sulfoxide.

Cryopreservation of chinese hamster ovary cells in tissue culture with either glycerol or dimethyl sulfoxide did not result in chromosome damage as measured by the sister chromatid exchange technique. These results are consistent with earlier negative reports in which the freezing and thawing of mammalian cells did not increase the frequency of micronuclei. No increases in the spontaneous mutation rates of several bacterial strains at different genetic loci were observed during the course of a number of years of storage at -196 degrees C. It is concluded that standard cryopreservation procedures are without genetic hazards. However, the well-documented effects of dimethyl sulfoxide on cell fusion and gene differentiation suggest caution in its use as a cryopreservative for animal and human embryos.