Cytogenetic analysis of 13 mesenchymal stem cell cultures isolated from normal human adipose tissue was carried out at different stages of culturing. The incidence of chromosomes 6, 8, 11, and X aneuploidy and polyploidy was studied by fluorescent in situ hybridization. During the early passages, monosomal cells were more often detected than trisomal ones. A clone with chromosome 6 monosomy was detected in three cultures during late passages.

We elaborated a method of preparing cytogenetic preparations of cultured multipotent mesenchymal stromal cells from the adipose tissue. It was found that karyotypic changes (monosomy, translocations) appear in some samples during culturing. Clones with changed karyotype were detected in 11-14-passage cultures from 2 of 7 individuals. The percent of aberrant cells in cultures from different individuals varied from 1.5 to 5.95 per 100 cells, which attested to karyotype instability. These data substantiate the need for cytogenetic control of cells before their transplantation into donor organism and further investigation of chromosome variability in stem cells.

Immunophenotype, proliferation rate, and genetic stability parameters of bone marrow multipotent mesenchymal stromal cells were studied. Despite the reduction of proliferative activity by passages 11-12, the cells retained the characteristic immunophenotype. The incidence of spontaneous aneuploidy for autosomes 6, 8, 11 and sex chromosomes was evaluated. Two cultures of mesenchymal stromal cells carrying aneuploid cell clones were detected: with chromosome 8 trisomy and X chromosome monosomy. The results indicate the possibility of genetic transformation and selection of mesenchymal stromal cells with abnormal karyotype during in vitro culturing.

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