Engineering Micro Oxygen Factory to Slow Tumor Progression by Hyperoxia Microenvironment

While hypoxia promotes carcinogenesis, tumor aggressiveness, metastasis, and resistance to oncological treatments, the impacts of hyperoxia on tumors are rarely explored because in vivo long-lasting oxygen supply is a big challenge. Herein, we constructed a micro oxygen factory, namely photosynthesis microcapsules (PMCs) by encapsulation of acquired cyanobacteria and upconversion nanoparticles in alginate microcapsules. This system enabled long-lasting oxygen supply by converting external radiations into red emissions for photosynthesis in cyanobacteria. PMC treatment suppressed NF-kB pathway, HIF-1α production and cancer cell proliferation. Hyperoxia microenvironments created by in vivo PMC implants inhibited hepatocarcinoma growth and metastasis, synergized the effects of anti-PD-1 in breast cancer. The engineered oxygen factory offers potential for tumor biology study in hyperoxia microenvironments and will inspire the exploration of oncological treatments.