[Comparative analysis of a new human cell line 4BL karyotype at long-term cultivation. Ploidy of chromosomal set]

Long-term cultivation of human cells, including stem cells, can lead to substantial transformation of the karyotype and occurrence of genetic instability. The aim of this research was a comparative cytogenetic study of the karyotype of a new human stem cell line 4BL at 160 and 205 passages. The absence of 10 and 13 pairs of chromosomes and the monosomy of chromosomes 4, 8, 10, 11, 13, 15, 17, 21, X were observed; also six regular marker chromosomes were detected. Chromosomes 1, 15 and 21 are involved in translocations t(l;11), t(5;15), t(12; 15), t(16;21). Modal class of the karyotype is within 41-43 chromosomes at both 160 and 205 passages. The frequency of polyploid cells have been increased from 2.8% at 160 passage up to 36% at 205 passage. Cells with a near-haploid karyotype were not detected at 205 passage (in contrast to 24.6% at 160 passages) and a decline of the level of premature separation of chromatids was observed. We assume stabilization of karyotype of the cell line 4BL at 205 passage and consider that further research is needed to predict the direction of karyotypic evolution of these cells in vitro.