Asymmetric Aneuploidy in Mesenchymal Stromal Cells Detected by In Situ Karyotyping and Fluorescence In Situ Hybridization: Suggestions for Reference Values for Stem Cells

Abstract

Cytogenetic testing is important to ensure patient safety before therapeutic application of mesenchymal stromal cells (MSCs). However, the standardized methods and criteria for the screening of chromosomal abnormalities of MSCs have not yet been determined. We investigated the frequency of cytogenetic aberrations in MSCs using G-banding and fluorescence in situ hybridization (FISH) and suggest reference values for aneuploidy in MSCs. Cytogenetic analysis was performed on 103 consecutive cultures from 68 MSCs (25 adipose-origin, 20 bone marrow-origin, 18 cord blood-origin, and 5 neural stem cells; 8 from adipose tissue of patients with breast cancer and 60 from healthy donors). We compared the MSC aneuploidy patterns with those of hematological malignancies and benign hematological diseases. Interphase FISH showed variable aneuploid clone proportions (1%-20%) in 68 MSCs. The aneuploidy patterns were asymmetric, and aneuploidy of chromosomes 16, 17, 18, and X occurred most frequently. Clones with polysomy were significantly more abundant than those with monosomy. The cutoff value of maximum polysomy rates (upper 95th percentile value) was 13.0%. By G-banding, 5 of the 61 MSCs presented clonal chromosomal aberrations. Aneuploidy was asymmetric in the malignant hematological diseases, while it was symmetric in the benign hematological diseases. We suggest an aneuploidy cutoff value of 13%, and FISH for aneuploidy of chromosomes 16, 17, 18, and X would be informative to evaluate the genetic stability of MSCs. Although it is unclear whether the aneuploid clones might represent the senescent cell population or transformed cells, more attention should be focused on the safety of MSCs, and G-banding combined with FISH should be performed.

Mesenchymal Stem and Progenitor Cells in Normal and Dysplastic Hematopoiesis—Masters of Survival and Clonality?

“…Asymmetric aneuploidy has been found to be prevalent in malignant hematologic diseases, but it remains unclear whether these aneuploid MSPC clones represent senescent or transformed cells [ 639 ]. MSPCs from patients with acute lymphoblastic leukemia demonstrated leukemia-associated chromosomal translocations in 10 of 10 patients’ samples analyzed, with proportions of translocation-positive MSPCs varying from 10% to 54% [ 640 ].…”

“…The concept of a common origin has recently also been supported by the observation that chromosomal aberrations mirroring those found in the corresponding leukemic blasts (in addition to distinct additional cytogenetic aberrations) were detected in AML-MSPCs in some AML patients [ 324 ]. Discrepant findings in the literature regarding the clonality of MSPCs may result from a lack of standardized methods for the screening of chromosomal abnormalities of MSPCs as well as the lack of harmonization of MSPC-purifying strategies, but also from the varying culture periods, different numbers of passages, and different tissue culture media used to grow cells prior to cytogenetic analyses [ 324 , 639 , 641 ].…”

Identity, proliferation capacity, genomic stability and novel senescence markers of mesenchymal stem cells isolated from low volume of human bone marrow

“…However, the occurrence of karyotypic instability in cultured hBM-MSCs has been documented. It has been admitted that genome instability enables tumor cells to acquire their characteristics [ 11 ], therefore the tumorigenesis potential of the hMSCs has become the most important concern for clinical use of MSCs [ 12 ]. Though, hBM-MSC studies presented highly conflicting results.…”

A model study for the manufacture and validation of clinical-grade deciduous dental pulp stem cells for chronic liver fibrosis treatment

“…ND, not detected; ns, not significant stable during culturing in vitro [42][43][44][45][46][47][48]. On the contrary, abundant recent studies have revealed that human MSCs exhibited spontaneous genomic alternation with increased passage number [49][50][51][52][53][54]. Previous chromosomal profiling studies also provide that karyotypical abnormalities and chromosomal instability in early passaged human MSCs disappear during the extended passage [51,[54][55][56].…”