Assessment of Ionizing Radiation-Induced Bystander Effect in Stem Cells

Abstract

The radiation induced bystander effect (RIBE), is well documented in the field of radiation biology. Vast majority of these effects are described in cell-culture systems, while in vivo validation and assessment of biological consequences remain uncertain. To mechanistically interrogate RIBE responses, this study was conducted. Accordingly, Albino rats’ right femurs were exposed to 0.25, 0.45 and 0.75 Gу γ-radiation. Rats were euthanized 1 day and ten days post irradiation, bone marrow total antioxidant capacity and mRNA expression level of Stromal Derived Growth Factor (SDF-1), Nerve Growth Factor (NGF) and Glial Fibrillary Acidic Protein (GFAP) genes; femur muscle LPO and blood frequency of micronucleated polychromatic erythrocytes (fMNPCEs) were all measured. Muscle femur LPO, total antioxidant capacity and mRNA expression level of all genes were significantly increased in left and right femur at 0.45 and 0.75 Gy 24 hours post irradiation and retained near control levels 10 days post irradiation. fMNPCEs became significantly higher 24 hours post irradiation and showed non-significant decrease ten days post irradiation at all doses. In conclusion, the increase in muscle femur LPO, bone marrow mRNA expression level of all genes, and total antioxidant capacity in left and right femurs indicate that a bystander effect exists in vivo.