Consomic Rat Models Identify Genetic Factors that Modulate Radiation-Induced Cardiac Toxicity and Inflammation

Abstract

plated at sub-confluence, then irradiated using a cesium irradiator. Senescence was determined by chromogenic beta-galactosidase assay (percent positive b-gal). 129Sv+/+ and 129Sv Fanca-/-mice received total body irradiation (TBI) using a Mark I Gamma Cell Irradiator. Subgroups of TBI and control mice were maintained on regular water or with 400uM MMS350 (Kalash, et al., Radiat Res, 180:474, 2013). Subgroups were sacrificed at 7days or 1 year after irradiation. Organs were immediately sectioned and scored for b-gal at 40x magnification. Statistical analysis was carried out using student's t-test. Results: Control non-irradiated cells showed no significant effect of genotype on senescence-associated b-gal staining at baseline (0.23% +/-0.23% in WT vs 0.23% +/-0.23% in Fanca-/-). By day 3 after 10Gy, b-gal staining was significantly induced in both WT (3.06% +/-1.08%, pZ0.007) and Fanca-/-cell lines (10.5% +/-1.17%, pZ0.001). Fanca-/showed significantly higher induction compared to WT (p<0.0001). Growth in MMS350 after 10Gy reduced senescence in Fanca-/-cell lines (8.12% +/-1.2%, pZ0.04). Seven days after 7Gy TBI, the spleen showed a significant increase in b-gal staining in both WT (0.74 +/-0.07 at 0Gy vs 1.81 +/-0.39 at 7Gy, pZ0.020) and in Fanca-/-(0.38 +/-0.20 at 0Gy vs 1.5 +/-0.45 at 7Gy, pZ0.029). At 1 year, WT showed a higher baseline staining compared to Fanca-/-in spleen (1.43 +/-0.10 in WT vs 0.83 +/-0.14 in Fanca-/-, pZ0.025). In contrast, 7.5 Gy caused a significant decrease in b-gal in WT at 1 yr (0.81 +/-0.12, pZ0.036) with little effect of MMS350. In Fanca-/-spleen, there was an increase at 1 yr (1.58 +/-0.13 after 7.5 Gy, pZ0.0009), which was reduced by MMS350 (1.17 +/-0.13). The brain showed no significant effect of time or genotype between groups. Conclusion: Fanca-/-bone marrow stromal cell lines showed greater irradiation induction of senescence over time compared to WT. MMS350 caused a reduction in the senescence in Fanca-/-. In vivo, the spleen showed a significant radiation induction in Fanca-/-and WT at 7 days. In contrast, WT spleen showed decreased senescence at 1 year after irradiation, while Fanca-/-spleen showed an increase. In the Fanca-/-mice, MMS350 reduced senescence at 1 year after irradiation.