Elevated frequencies of micronuclei in cultured fibroblasts after freezing and thawing.
Spontaneous micronuclei (MN) were determined in 69 fibroblast lines in the first subculture after cryoconservation. 45 cultures (65%) showed micronuclei in the normal range (less than 10 MN/500 cells), but 24 (35%) exhibited an elevation up to 60 MN/500 cells. In order to determine whether freezing and thawing is responsible for the enhanced MN level we studied the persistence of elevated MN in 10 cell cultures after freezing and thawing, and found that the MN levels returned to normal after 3 subcultures. In addition, the micronucleus formation before and after freezing was investigated in 2 newly established cell cultures obtained from probands whose cells had a particularly high number of MN. Both cultures had regular MN levels before freezing but a more than doubled number of MN when frozen samples were recultivated. This effect of the freezing procedure was confirmed with 5 separate biopsies obtained from the same donor. Since a freezing-related increase in MN was constantly observed in cells from some individuals but not in others, it might be possible that it is a constitutive trait which causes cultured fibroblasts of some individuals to be hypersensitive to the freezing and thawing procedure. It is also noteworthy that fibroblasts from 8 out of 12 probands with a familial malignant melanoma exhibited this phenomenon.
Schmidt-Preuss
U
U
Department of Occupational Medicine, University of Hamburg, F.R.G.
Roser
M
M
Weichenthal
M
M
Rüdiger
H W
HW
D001706:Biopsy; D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology / Q000648:ultrastructure; D005615:Freezing; D006801:Humans; D008545:Melanoma / Q000473:pathology; D048629:Micronuclei, Chromosome-Defective / Q000648:ultrastructure*; D012016:Reference Values; D012867:Skin / Q000166:cytology / Q000473:pathology / Q000648:ultrastructure; D012878:Skin Neoplasms / Q000473:pathology