A systemic-absorption-blocked (SEAL) nanoplatform for mRNA-based local immunotherapy.

Rapid transport of locally delivered mRNA lipid nanoparticles (mRNA-LNPs) into systemic circulation induces off-target protein expression and undesired side effects. Here we describe a systemic-absorption-blocked (SEAL) nanoplatform that achieves efficient mRNA delivery to disseminated peritoneal tumors using LNPs with minimized systemic exposure. Intraperitoneal administration of SEAL LNPs significantly reduces unintended mRNA expression in the liver and spleen, while maintaining robust protein expression in peritoneal tumors. Incorporation of cationic helper lipid is demonstrated essential for SEAL LNPs to minimize their systemic exposure. Using an in vitro transwell model to simulate the mesothelial barrier, we further elucidate that SEAL LNPs favor clathrin-mediated endocytosis and Golgi apparatus less involved intracellular trafficking in mesothelial cells, leading to reduced capability to penetrate the mesothelium for lymphatic transport. Intraperitoneal delivery of IL-12 mRNA (mIL-12) using the SEAL platform generates localized IL-12 expression with reduced systemic toxicity, leading to potent antitumor effects in mice bearing colorectal cancer (CRC) peritoneal dissemination. Delivery of mRNA-encoded therapeutic proteins using this platform presents a promising strategy to address peritoneal carcinomatosis.