RSL3-loaded nanoparticles amplify the therapeutic potential of cold atmospheric plasma

Cold atmospheric plasma (CAP) has exhibited exciting potential for cancer treatment. Reactive oxygen and nitrogen species (RONS), the primary constituents in CAP, contribute to cancer cell death by elevating oxidative stress in cells. However, several intrinsic cellular antioxidant defense systems exist, such as the glutathione peroxidase 4 (GPX4) enzyme, which dampens the cell-killing efficacy of CAP. RAS-selective lethal 3 (RSL3), also known as a ferroptosis inducer, is a synthetic GPX4 inhibitor. Therefore, we hypothesized that RSL3 can amplify CAP-induced cell death by inhibition of GPX4. In this study, we showed that RSL3 loaded in poly (ethylene glycol)-block-poly(lactide-co-glycolide) (PLGA-PEG) nanoparticles can enhance CAP-induced cell deaths in 4T1 tumor cells. Furthermore, the combination of CAP and RSL3 also promoted cancer immunogenic cell death (ICD), induced dendritic cell (DC) maturation, and macrophage polarization, initiating tumor-specific T-cell mediated immune responses against tumors. For in vivo application, RSL3@NP was co-delivered with CAP via injectable Pluronic hydrogel. In 4T1-bearing mice, hydrogel-mediated delivery of CAP and RSL3-loaded nanoparticles can effectively elicit potent anti-tumor immune responses and inhibit tumor growth.