362 A Novel Animal Model of Radiation-Induced Heart Disease Using Photon Radiation

OBJECTIVES/GOALS: The purpose of this study is to develop a clinically relevant mouse model of Radiation-Induced Heart Disease (RIHD) and characterize the resulting phenotype to find biomarkers and therapeutic targets as well as to understand the changes in cellular and molecular mechanisms of bioenergetics. METHODS/STUDY POPULATION: We used a two-beam method in the axillary region targeting the heart to irradiate male BALB/c mice at an isodose of 22, 16 and 8 Gray (Gy). We examined cardiac damage (i.e., vacuolization), inflammation, and DNA damage at 10 days post irradiation using histology and immunohistochemistry of heart tissue and cardiac function at day 35 by echocardiography. Additionally, cardiac tissue of mice irradiated at 22 Gy was collected at day 10 and day 35 post irradiation and sent for RNA sequencing. Data from RNA sequencing was analyzed using gProfiler, GSEA, and Cytoscape to enrich and visualize differentially expressed genes. RT-qPCR was performed to validate findings of significantly differentially expressed genes. RESULTS/ANTICIPATED RESULTS: Significantly increased phosphorylation of H2A.X indicated that irradiated mice were undergoing DNA double strand break repair indicating cardiac damage. Additionally, we found that regulators of mitochondrial function were decreased in the heart at day 10 for all doses. We found that mice that received 22 Gy developed cardiomyopathy at day 35 based on increased global longitudinal strain (GLS). Radiation decreased T cells, macrophages, and mast cells in the heart of irradiated mice by RT-qPCR at day 10 indicating damage to immune cells by radiation at all doses. Thus, we successfully created a clinically relevant model of RIHD in male BALB/c mice. DISCUSSION/SIGNIFICANCE: Patients undergoing radiation therapy for thoracic malignancies can develop cardiomyopathy (DCM) due to radiation damage. Previously published animal models utilized mouse strains resistant to developing DCM (female mice, C57BL/6 strain) and used high doses of radiation. Establishing a translational model is crucial for prevention of RIHD.