Arginine-Rich Peptide-Based mRNA Nanocomplexes Efficiently Instigate Cytotoxic T Cell Immunity Dependent on the Amphipathic Organization of the Peptide.

To date, the mRNA delivery field has been heavily dominated by lipid-based systems. Reports on the use of nonlipid carriers for mRNA delivery in contrast are rare in the context of mRNA vaccination. This paper describes the potential of a cell-penetrating peptide containing the amphipathic RALA motif to deliver antigen-encoding mRNA to the immune system. RALA condenses mRNA into nanocomplexes that display acidic pH-dependent membrane disruptive properties. RALA mRNA nanocomplexes enable mRNA escape from endosomes and thereby allow expression of mRNA inside the dendritic cell cytosol. Strikingly, RALA mRNA nanocomplexes containing pseudouridine and 5-methylcytidine modified mRNA elicit potent cytolytic T cell responses against the antigenic mRNA cargo and show superior efficacy in doing so when compared to RALA mRNA nanocomplexes containing unmodified mRNA. RALA's unique sequence and structural organization are vital to act as mRNA vaccine vehicle, as arginine-rich peptide variants that lack the RALA motif show reduced mRNA complexation, impaired cellular uptake and lose the ability to transfect dendritic cells in vitro and to evoke T cell immunity in vivo

Gene therapy with RALA/iNOS composite nanoparticles significantly enhances survival in a model of metastatic prostate cancer

Recent approvals of gene therapies by the FDA and the EMA for treatment of inherited disorders have further opened the door for assessment of nucleic acid pharmaceuticals for clinical usage. Arising from presence of damaged or inappropriate DNA, cancer is a condition particularly suitable for genetic intervention. The RALA peptide has been shown to be a potent non-viral delivery platform for nucleic acids. This study reports that complexation of RALA with a plasmid encoding inducible nitric oxide synthase (iNOS) DNA produces functional cationic nanoparticles with gene expression in PC-3 prostate cancer cells. Furthermore, repeated administrations of RALA/DNA nanoparticles to immunocompetent mice did not produce an immunological response, be that neutralization of the vector or release of inflammatory mediators. RALA/CMV-iNOS reduced the clonogenicity of PC-3 cells in vitro, and in an in vivo model of prostate cancer metastasis, systemically-delivered RALA/CMV-iNOS significantly improved the survival of mice. These results further validate RALA as a genetic cargo delivery vehicle and iNOS as a potent therapy for the treatment of cancer