mRNA transfection of dendritic cells: Synergistic effect of ARCA mRNA capping with Poly(A) chains in cis and in trans for a high protein expression level

The occurrence of translation mechanism in the cytosol offers advantages to mRNA transfer over DNA-based transfection in non-dividing cells. Here, we sought to optimize mRNA constructs allowing a high level of protein upon lipofection. We found that luciferase into mouse dendritic cells (JAWSII cells) was ∼20-fold higher when the luciferase mRNA was capped with 3′-O-methyl-m75′Gppp5′G (anti-reverse cap analogue; ARCA) than with m75′Gppp5′G (CAP). Adding a Poly(A) tail of 100 instead of 64 adenosines in cis increased by ∼35-fold more the protein level. Finally, ARCA-Luc-mRNA-A100 construct was 700-fold better efficient than the CAP-Luc-mRNA-A64 one. Moreover, co-transfection with free Poly(A) chains in trans enhanced by 100% the luciferase level. The efficiency of ARCA-mRNA-A100 construct was validated in immature and mature human CD34-derived dendritic cells. Such mRNA construct was also successful to obtain high level of MART-1 tumor antigen.