Medical Radiology and Radiation Safety. 2026. Vol. 71. № 5
DOI:10.33266/1024-6177-2026-71-5-13-19
D.V. Fomina1, 3, A.V. Tochilenko1, 3, T.P. Kalinin3, R.M. Sarimov4, E.O. Levintas3, A.S. Kuzmina3, S.I. Shubina3, S.A. Abdullaev1, 2, 3
EVALUATION OF THE «BYSTANDER EFFECT» WHEN INJECTING MICE WITH X-RAY-IRRADIATED OR HYDROGEN PEROXIDE-TREATED MITOCHONDRIAL DNA
1 N.N. Semenov Federal Research Center for Chemical Physics, Moscow, Russia
2 Institute of Theoretical and Experimental Biophysics, Pushchino, Russia
3 A.I. Burnazyan Federal Medical Biophysical Center, Moscow, Russia
4 A.M. Prokhorov General Physics Institute, Moscow, Russia
Contact person: S.A. Abdullaev, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
ABSTRACT
Purpose: To assess the possibility of the “bystander effect” occurring when non-irradiated mice were injected with mitochondrial DNA irradiated with X-rays or treated with hydrogen peroxide.
Material and methods: Male Balb/c mice aged 2 months were used. Mitochondrial DNA (mtDNA) was injected intraperitoneally in saline (20 mg/mouse) – intact, irradiated at a dose of 5 Gy, and treated with hydrogen peroxide. mtDNA was isolated from mouse liver mitochondria. To purify the obtained mtDNA from nuclear DNA (nDNA) fragments, the mitochondria were treated with nuclease. Animals were sacrificed 1, 3, 7, 14, 21, and 30 days after mtDNA injection. The following parameters were then determined: mtDNA copy number in tissue cells, mitochondrial gene expression, intracellular mtDNA damage, the relative number of mutant mtDNA copies, and the level of micronuclei in cells. The brain, heart, liver, and spleen were used to analyze these parameters. Micronuclei levels were determined in bone marrow cells.
Results: Injecting mice with intact extracellular mitochondrial DNA irradiated at a dose of 5 Gy and treated with hydrogen peroxide resulted in a general pattern of changes. From the moment of injection, the mtDNA copy number in brain and heart tissues decreased by approximately 2‒3 times. In liver and spleen cells, the mtDNA copy number increased approximately 3-fold over 24 hours, and after 72 hours, the mtDNA copy number decreased to control levels. In brain and heart cells, the amount of ATP6 gene transcripts increased for up to 72 hours after injection. After 72 hours, the relative amounts of ATP6 gene transcripts in brain and heart tissues exceeded the control level by 10 and 12 times, respectively. A decrease in this parameter was then observed, with ATP6 gene transcript levels still exceeding control levels by five times 14 days after mtDNA injection. However, these changes were not considered significant due to the large standard deviation. In liver and spleen cells, ATP6 gene transcript levels increased threefold relative to control levels seven days after mtDNA injection. Changes in parameters such as mtDNA damage and mutations in these tissues, as well as micronuclei formation in bone marrow cells after mtDNA injection, did not differ significantly from control values.
Conclusion: Thus, based on the obtained research results, the hypothesis that mitochondrial extracellular DNA can cause a “bystander effect” at the level of the whole organism has not been confirmed.
Keywords: mtDNA, bystander effect, oxidative stress, X-ray exposure
For citation: Fomina DV, Tochilenko AV, Kalinin TP, Sarimov RM, Levintas EO, Kuzmina AS, Shubina SI, Abdullaev SA. Evaluation of the «Bystander Effect» when Injecting Mice with X-Ray-Irradiated or Hydrogen Peroxide-Treated Mitochondrial DNA. Medical Radiology and Radiation Safety. 2026;71(5):13–19. DOI:10.33266/1024-6177-2026-71-5-13-19
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Conflict of interest.The authors declare no conflict of interest.
Financing. This work was supported by the Russian Science Foundation (project No. 24-24-00446).
Contribution. Article was prepared with equal participation of the authors.
Article received: 20.04.2026. Accepted for publication: 25.05.2026.