Effect of Thrombopoietin Receptor Agonist Romiplostim on the Ionizing Radiation‐Induced Premature Aging

Environmental stressors, such as ionizing radiation, accelerate aging by causing DNA damage and triggering pathways that lead to cell cycle arrest, apoptosis, and subsequent inflammation. The thrombopoietin receptor agonist romiplostim (RP), which is used as a clinical treatment for chronic idiopathic thrombocytopenic purpura and aplastic anemia, is known to be promising in reducing radiation-induced tissue damage. In this study, we established a mouse model of radiation-induced premature aging to evaluate the potential of RP in ameliorating this process. Female C57BL/6JJcl mice were subjected to total body irradiation with various irradiation schedules. Mice irradiated with 5 Gy every 4 weeks (total dose of 10 Gy over 2 months) showed a significant aging phenotype, including graying hair and elevated serum aging markers (CDKN2A/p16^INK4a, tumor necrosis factor-α (TNF-α), and C-reactive protein), compared with sham-irradiated controls. RP was intraperitoneally administered to the mouse model (10 μg/kg weekly or 50 μg/kg every 4 weeks). Treatment significantly reduced TNF-α levels by 15% and the area of graying body hair by 70%. Although bone marrow cell recovery was incomplete, spleen cell counts were significantly restored (2-fold) by 50 μg/kg RP, and SA-β-gal activity, a marker of cellular senescence, was also significantly suppressed by approximately 15%. These findings suggest that RP may partially ameliorate radiation-induced premature aging, providing a basis for future research addressing health issues associated with aging and radiation exposure.