Comparison of the dynamics of DNA damage in blood leukocytes and survival of mice after total body irradiation with Bragg peak carbon ions or x-rays

Abstract

This study has determined a survival rate of mice irradiated with accelerated carbon ions (450 MeV/nucleon) in the Bragg peak or X-ray at a dose of 6.5 Gy, using the comet assay. Levels of DNA damage (%TDNA) in blood leukocytes from mice were measured 1 day before, 1-23 days after exposure to carbon ions and 1-28 days after exposure to X-ray radiation at the same dose. According to survival and % TDNA parameters, it was found that a damaging effect of carbon ions is greater than that of X-rays and substantial variations in % TDNA, which occur in individual animals, could appear to cause individual differences in the development of genome instability in the long term. It is assumed that a higher % TDNA in leukocytes after carbon ion exposure compared to that of X-rays, a wide range of variations and asynchronous changes in individuals in the post-irradiation period are associated with the induction of clustered DNA damages and mitochondrial dysfunction, and are also due to genetic and epigenetic factors. The results obtained point to the need to assess the state of blood leukocytes in animals with a heterogeneous genetic background using the comet assay before irradiation in order to form a group with similar %TDNA values. The revealed differences in individual laboratory animals require further study in order to improve animal models in the light of the development of personalized biomedicine.