Bacteria Outer Membrane-Based Oxygen Gels Alleviate Tumor Hypoxia for Enhanced Systemic Immune Response to Radiotherapy
Radiotherapy (RT) is a standard cancer treatment that directly kills tumor cells and promotes systemic immune responses. However, RT can exacerbate tumor hypoxia, which suppresses dendritic cell (DC) antigen presentation and weakens systemic anti-tumor immunity. Here, we report oxygen-loaded in situ gels carrying bacterial outer membrane (MOGel) that slowly degrade to release oxygen and bacterial outer membrane (OM). Oxygen release alleviates tumor hypoxia, while OM continuously activates DCs, enhancing their antigen-presenting capability. In vitro, MOGel combined with RT induced the strongest tumor cell apoptosis. In an orthotopic colon cancer model, MOGel+RT achieved an 80% tumor suppression rate. Notably, MOGel+RT elicited an enhanced abscopal effect, with hypoxia relief and enhanced DC activation contributing to systemic immune responses. These findings suggest that OM-based oxygen gels offer a novel strategy to enhance systemic immune responses to RT.