Low-Dose Ionizing Radiation Affects Mesenchymal Stem Cells via Extracellular Oxidized Cell-Free DNA: A Possible Mediator of Bystander Effect and Adaptive Response

Figure 8

Low-dose radiation and cfDNAox fragments cause a short-term arrest of cell cycle and decreases proliferation. (a) (1) Proportions of cells that contain the amount of DNA characteristic for G1, S, and G2/M phases of the cell-cycle (flow cytometry). (a) (2) Proportions for control cells,10 cGy irradiated cells, and cells treated with oxidized DNA. (b) Dynamics of the change of fraction of proliferating cells (Ki-67+ fraction) in the population (flow cytometry): (1) distribution of cells with varying Ki-67 content; (2) average signal intensity of FL1-Ki-67+ in irradiated cells (10 cGy, 15 min and 2 h after exposure) and cells exposed to cfDNAox (50 ng/ml, 30 min and 2 h). Significantly differs from control (). (c) Change of PCNA level in control and exposed cells (flow cytometry): (1) distribution of cells with varying Ki-67 contents; (2) average PCNA fluorescence. Significantly different from control ().

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