Induction and assessment of persistent radioresistance in murine leukocytes in vivo.
Biochem Biophys Rep 2022;
31:101296. [PMID:
35707716 PMCID:
PMC9189778 DOI:
10.1016/j.bbrep.2022.101296]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 05/27/2022] [Accepted: 06/01/2022] [Indexed: 11/25/2022] Open
Abstract
The aim of the present study was to investigate whether weekly exposure to gamma rays causes a persistent increase in the number of radioresistant leukocytes in mice in vivo. Using the comet assay, 1 Gy radiation exposure decreased the percentage of leukocytes with less than 5% DNA in the tail (<5% DNAT), and we propose that radioresistance induction might increase the number of cells with <5% DNAT after radiation exposure. We exposed mice to 1 Gy gamma rays weekly for four weeks or 2 Gy per week for nine weeks. We observed a significant increase in cells with <5% DNAT after the third week and up to nine weeks of exposure. We exposed animals to gradually increasing radiation doses and finally challenged the lymphocytes with 1 Gy radiation both in vivo and in vitro. We observed increased radioresistance in vitro, providing evidence that a cellular process is involved. However, more radioresistance was observed in vivo than in vitro, suggesting a physiological effect. Cells challenged in vitro were maintained on ice during and after exposure, which likely caused a reduction in DNA repair. Radioresistance induction likely arose from mutation selection in stem cells because leukocytes are unable to proliferate in peripheral blood.
First evidence of cell radioresistance induced in vivo in mice.
Leukocyte precursor cells in vivo a model for study radioresistance induction.
Irradiation-division cycles in vivo cause long-lasting cellular radioresistance.
Increase of <5% DNA at tail after irradiation an index of cell radioresistance.
Course of radioresistance caused by mutation-selection differ from adaptive response.
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