IL-12 minicircle delivery via extracellular vesicles as immunotherapy for bladder cancer.

Interleukin-12 (IL-12) holds significant potential in cancer therapy; however, its clinical applicability is hindered by dose-limiting toxicity. Delivery of the IL-12 gene directly to tumours for constitutive IL-12 expression is a possible strategy to enhance its effectiveness while minimizing systemic toxicity. In this study, we investigate the potential of red blood cell-derived extracellular vesicles (RBCEVs) as a carrier for Il-12 plasmid delivery. We demonstrate that RBCEVs can be loaded with minicircle plasmid encoding IL-12 and delivered to MB49 bladder cancer cells for IL-12 expression. The expression of transgenes from minicircles was significantly higher than from the parental plasmids. RBCEV-mediated IL-12 expression stimulated immune responses in mouse splenocytes. Intratumoral delivery of Il-12 plasmid-loaded RBCEVs suppressed bladder cancer tumour growth, stimulated immune responses and promoted immune cell infiltration. In conclusion, our study demonstrates the promising potential of RBCEVs as an effective, safe and redosable nucleic acid drug delivery platform for IL-12.