Lipoplexes carrying mRNA encoding Gag protein modulate dendritic cells to stimulate HIV-specific immune responses

Aim: Cationic lipids (Lipofectamine (TM) [Invitrogen, Merelbeke, Belgium] and 1,2-dioleoyl-3-trimethylammonium-propane/1,2-dioleoyl-sn-glycero-3-phosphoethanolamine) and polymers (jetPEI (TM) and in vivo-jetPEI (TM) [Polyplus-transfection, Illkirch, France]) were evaluated for their potential to deliver mRNA to monocyte-derived dendritic cells. Materials & methods: Lipoplexes and polyplexes, containing mRNA encoding GFP or Gag protein, were incubated with human monocyte-derived dendritic cells and transfection efficiencies were assessed by flow cytometry. Results: Lipofectamine was by far the most efficient in mRNA delivery, therefore it was used in further experiments. Incubation of monocyte-derived dendritic cells isolated from HIV-1-positive donors with mRNA encoding Gag protein complexed to Lipofectamine resulted in 50% transfection. Importantly, coculture of these Gag-transfected dendritic cells with autologous T cells induced an over tenfold expansion of IFN-gamma- and IL-2-secreting CD4(+) and CD8(+) T cells. Conclusion: Cationic lipid-mediated mRNA delivery may be a useful tool for therapeutic vaccination against HIV-1. This approach can be applied to develop vaccination strategies for other infectious diseases and cancer.