AdMSC spheroids encapsulating antioxidant hybrid protein carrier for irradiation-damaged salivary gland repair.

Radiation therapy for head and neck cancer often causes xerostomia, a chronic salivary gland (SG) dysfunction driven by excessive reactive oxygen species (ROS), severely impacting the quality of life of patients. Existing treatments, such as artificial saliva or SG stimulants, offer only temporary relief. We developed a novel therapeutic system combining glutathione (GSH)-conjugated gelatin (Gel) hybrid protein-based cell carrier (GC) with adipose-derived mesenchymal stem cell (AdMSC) spheroids. This hybrid protein carrier (GC) extended the antioxidant activity of GSH by overcoming its short half-life and enabled efficient encapsulation and delivery of AdMSC spheroids to irradiation (IR)-damaged SGs. The 3D spheroids enhanced vascular endothelial growth factor (VEGF) expression through hypoxic core formation, promoting angiogenesis. In an IR-damaged mouse model, spheroid-encapsulated GC increased SOD2 expression and decreased 8-OHdG and NOX4 levels, effectively mitigating oxidative stress, fibrosis, and apoptosis, while accelerating angiogenesis. SG structural regeneration and functional recovery were confirmed using histological and immunohistochemical analyses following spheroid-encapsulating GC treatment. These results demonstrate the synergistic effects of ROS-scavenging activity from GC and paracrine signaling from AdMSC spheroids. This groundbreaking spheroid-encapsulating GC improves SG regeneration and functional recovery by integrating antioxidant activity with angiogenic effects, offering a paradigm-shifting solution for other oxidative stress-mediated tissue disorders.