Abstract: Objective:To establish a radiation injury model of mouse submandibular gland (SMG) organoids to provide support for the research on the repair of radiation injury of the salivary gland.Methods:The SMG tissue of 4-week-old mice was digested into single cell suspension by collagenase, and then the suspension was inoculated into Matrigel for culture and passage.The growth morphology of SMG was observed by inverted phase contrast microscope.The expressions of cytokeratin(CK8)and aquaporin(AQP5)were detected by immunofluorescence after tissue embedding.The content of salivary amylase (AMS) in the culture supernatant was determined by enzyme-linked immunosorbent assay(ELISA).The mouse SMG organoid model was irradiated with different doses(0 Gy、5 Gy、10 Gy、15 Gy)by electron linear accelerator.The cell viability of each irradiation dose group was detected by the ATP cell viability kit.Results:The mouse SMG organoids grew like round spheres, and the lobular structures were formed with the passage culture.CK8 and AQP5 staining were positive in mouse SMG organoids, and AMS expression was detected in the supernatant of cell culture, which confirmed that SMG organoids were derived from glandular epithelium and had the function of secreting AMS.Radiation slowed down the proliferation of organoids, and the shape around the sphere was approximately disintegrated.ATP cell viability detection showed that the cell viability decreased with the increase of irradiation dose (P< 0.05).When the irradiation dose was 10 Gy, the cell viability was about 50% of that of the 0 Gy group.Conclusion:The mouse SMG organoid model is successfully established, and 10 Gy is the most appropriate radiation dose for the research on the repair of radiation injury of salivary gland.