Establishment and Histopathological Analysis of Radiation Induced Mucositis Mouse Model

Introduction: Radiation-induced mucositis (RIM) is a common side effect of radiation therapy in head and neck cancer patients. Efficient remedy to prevent the occurrence or reduce the severity of RIM is developing. Therefore, an ideal animal model with grading methods for RIM is imperative. Objective: In this study, we established a mouse model and set up a grading method for the severity of RIM. Materials and methods: Local irradiation of single dose was administered toward the snout extending the anterior 8 mm of the tongue. Mice were sacrificed on day 0, 3, 6, 9, 12, and RIM on tongues were graded by histopathological analysis and expression of targeted pro-inflammatory cytokine. Results: Moderate atrophy of filiform papilla with generalized edema and moderate inflammatory infiltration were observed starting from day 9. At day 12, disruption of epithelial layer with overlying pseudomembrane were detected and accompanied with a moderate to severe inflammatory cell infiltration in the submucosa. A panel of pro-inflammation cytokines was increased starting from day 12 compared to non-irradiated controls. Based on the histopathological characteristic and parameters, we established a novel grading system for RIM on the dorsal surface mucosa of tongue. Conclusion: The established RIM mouse model and the grading parameters could provide a useful platform to evaluate the prophy¬lactic and therapeutic remedy for RIM.