Mannosylated and histidylated LPR technology for vaccination with tumor antigen mRNA.

mRNA-based vaccines are currently being developed for treating various diseases including cancers. For this purpose, synthetic or in vitro transcribed (IVT) mRNA encoding tumor antigen offers several advantages over plasmid DNA encoding tumor antigen including better delivery and security. In this chapter, we report the preparation of mannosylated mRNA nanoparticles termed mannosylated lipopolyplexes or Man-LPR loaded with mRNA encoding a melanoma antigen. This formulation enhances the transfection of dendritic cells (DCs) in vivo and the anti-B16F10 melanoma vaccination in mice. The mRNA is formulated with histidylated liposomes and a histidylated polymer. Those pH-sensitive vectors promote membrane destabilization in endosomes upon the protonation of their histidine groups, allowing nucleic acid delivery in the cytosol. To favor DCs targeting via the mannose receptor, a mannose lipid is incorporated in the liposomes. Here, we provide protocols for the preparation of mannosylated liposomes, the synthesis of mRNA, mice immunization based on systemic injection, measurement of the cellular immune response and determination of the number of transfected splenic DC.