Systemic trafficking of mRNA lipid nanoparticle vaccine following intramuscular injection generates potent tissue-specific T cell response

The mRNA lipid nanoparticles (LNPs) represent a new generation of vaccine carriers designed to elicit potent immune responses against infectious diseases and cancer. Despite the clinical success and rapid advancements in mRNA LNP technologies, the trafficking patterns of LNPs after intramuscular (i.m.) administration and the subsequent tissue-specific immunological effects have not been systematically characterized. Here, we report that trafficking of mRNA LNPs to different organs following i.m. injection is crucial for the induction of tissue-specific immunity beyond systemic immune response, particularly in tissue-resident CD8+ T cell generation, which is important for localized defense. By fine-tuning the composition of mRNA LNPs, trafficking patterns to systemic organs can be modulated, which can alter the resulting tissue-specific immune response. Formulations with a greater ability to enter the bloodstream can preferentially localize and transfect cells in specific organs like the liver, elicit stronger tissue-specific CD8+ T cell immune responses, and achieve enhanced efficacy in a liver tumor model. These findings highlight the potential to tailor mRNA LNP compositions to modulate trafficking following i.m. injection, thereby providing novel strategies for designing tissue-specific vaccines. Such strategies are particularly valuable for organ-specific diseases like cancer and infectious diseases, where tissue targeting and long-lasting immunity are essential for therapeutic success.