Scapevs Alleviate Radiation-Induced Salivary Glands Injury By Dna Repair

To investigate the therapeutic role of extracellular vesicles derived from stem cells from apical papilla (SCAP-EVs) in alleviating radiation-induced salivary gland and its potential mechanism. The submandibular region was radiated in 8-week-old Sprague-Dawley rats to establish the radiation-induced salivary gland injury model, and SCAP-EVs was injected in the submandibular region. Salivary flow rate was tested and haematoxylin and eosin staining were performed to observe the pathological changes after 14 and 28 days. Immunohistochemical and immunofluorescence staining were used to assess the expression of aquaporin 5 (AQP5) and phosphor-H2AX (γ-H2AX) in submandibular gland. In vitro, salivary gland epithelial cells (SGECs) isolated from rats were irradiated and treated with different doses of SCAP-EVs. Ki-67 immunofluorescence staining and flow cytometry were used to detect the SGEC proliferation and apoptosis level. The expression of γ-H2AX was evaluated by western blot and immunofluorescence, and comet assay was performed to assess the deoxyribonucleic acid damage level. SCAP-EVs significantly enhanced salivary secretion in rats with radiation-induced salivary gland injury, increased the expression of AQP5 and reduced the proportion of γ-H2AX -positive SGECs in submandibular gland. In vitro, SCAP-EVs upregulated the proliferation rate, reduced apoptosis level and restored AQP5 protein expression of irradiated SGECs. Moreover, the expression of γ-H2AX and comet tail moments of irradiated SGECs reduced after the treatment of SCAP-EVs. SCAP-EVs could alleviate radiation-induced salivary gland injury by attenuating the deoxyribonucleic acid damage level of irradiated SGECs.