Comparative Study of Mitochondrial DNA Abnormalities in Mesenchymal Stem Cells after Exposure to X-Ray Radiation in Low and Medium Doses

The effects of low- and medium-dose X-rays on mitochondrial function in mesenchymal stem (stromal) cells (MSCs) were compared. Irradiation at a dose of 80 mGy did not lead to mitochondrial disorders in MSCs by all analyzed parameters, while 24 h after irradiation at a dose of 2000 mGy, damage to mitochondrial and nuclear DNA was recorded, as well as the initiation of replicative synthesis of mitochondrial DNA involving damaged molecules, which led to an increase in the level of heteroplasmy. The increased level of mitochondrial DNA heteroplasmy after irradiation at a dose of 2000 mGy was accompanied by a decrease in the expression of genes involved in the process of oxidative phosphorylation and regulating mitochondrial dynamics.