Aneuploidy analysis in fibroblasts of human premature aging syndromes by FISH during in vitro cellular aging

Cultured cells from human premature aging syndromes show premature replicative senescence and as such might serve as models for genetic studies of cellular replicative senescence/aging. To date, no systematic study on chromosome-specific aneuploidy in premature aging syndromes has been carried out using molecular-cytogenetic techniques. We, therefore, have performed a comparative analysis of chromosome-specific aneuploidy levels at both interphase and metaphase in earlier (younger) and later (older) passage fibroblasts from two normal male and female versus six male and female premature aging syndromes (Cockayne, Hutchinson-Gilford and Werner) by FISH. We have used seven chromosome-specific DNA probes (nos. 1, 4, 6, 8, 10, 15, X) and four DNA probes (nos. 1, 4, 6, X) for females and males, respectively. Our data on total aneuploidy of each chromosome in all cell cultures indicated that significantly higher percentages of aneuploid cells were detectable at interphase than at metaphase. Also, the interphase aneuploidy levels of all chromosomes under study were significantly higher in cells from the syndromes as compared to those of the normal controls at both earlier and later passages. In general, the interphase aneuploidy level of each of the chromosomes in both the control and experimental cell cultures increased with in vitro proliferation and aging, although to a much lesser extent in the controls. The aneuploidy levels, however, varied widely from chromosome to chromosome in each case. Since adequate numbers of mitotic cells were not always available in some later passage cells of various premature aging syndromes, metaphase chromosome analysis for all chromosomes under study was not always possible at this stage, but interphase cytogenetics was very informative in all cases. No consistent pattern of chromosome-specific aneuploidy was detected in the earlier passage cells (younger cells) of the syndromes. However, the later passage cells (older cells) from all three female syndromes consistently showed the highest aneuploidy levels for the X chromosome at interphase.