Changes in the Number of Dna Repair Protein Foci in Tomography-Irradiated Human Mesenchymal Stem Cells

Purpose: Comparative analysis of changes in the number of γH2AX, 53BP1 and pATM foci in human mesenchymal stem/stromal cells (MSCs) after irradiation during single and five-time sequential computed tomography (CT). Additionally, as a positive control, changes in these parameters were studied after irradiation of cells using an X-ray machine at a dose of 2000 mGy. Material and methods: A primary culture of human MSCs was obtained from the collection of BioloT LLC (Russia). A TOSHIBA AQUILION 64 computed tomograph (Japan) was used for cell irradiation. Dosimetric monitoring was carried out using the thermoluminescent method with aluminophosphate dosimeters and magnesium borate-based dosimeters. For comparative studies and obtaining a positive control, a RUST-M1 X-ray biological unit (Russia) equipped with two X-ray emitters (dose 2000 mGy, dose rate 0.85 Gy/min) was used. Immunocytochemical staining using antibodies to γH2AX, 53BP1 and pATM was used for quantitative assessment of γH2AX, 53BP1 and pATM foci. Statistical significance was assessed using analysis of variance (ANOVA). Results: The studies showed that irradiation of MSCs during CT (absorbed doses during single CT approximetly 88 mGy) causes a statistically significant increase in the number of foci of the proteins γH2AX, 53BP1 and pATM, recorded 0.5 h after irradiation. However, no statistically significant increase in the number of residual γH2AX, 53BP1 and pATM foci was observed 24 h after irradiation compared to the control values. In general, a comprehensive assessment of the number of γH2AX, 53BP1 and pATM protein foci can be recommended for early biodosimetry of irradiation during CT.