Abstract
Therapeutic effects of in vivo gene therapy, which aims to treat diseases by administering therapeutic genes to patients, are obtained via proteins expressed from the gene administered. Therefore, to optimize the therapeutic effects of such therapy, it is important to control not only the tissue distribution of gene vectors but also that of proteins expressed from the vector. Studies using protein pharmaceuticals have clearly demonstrated that the therapeutic effect depends largely on the spatiotemporal distribution of proteins, such as area under the curve and mean residence time. These results strongly suggest that precise control of the spatiotemporal distribution of proteins increases the efficacy of in vivo gene therapy. Based on these considerations, we tried to increase the therapeutic effect of plasmid DNA-based gene therapy by controlling the profile of proteins expressed form vectors. To increase the residence time of proteins, we developed plasmids with few CpG motifs and achieved sustained expression of proteins at therapeutic levels for as long as several months. Sustained expression of murine interferon γ was highly effective in inhibiting metastatic tumor growth and atopic dermatitis in mouse models. Thus, designing plasmid vectors is a promising approach not only to controlling the spatiotemporal distribution of proteins, but also to increasing the therapeutic potency of in vivo gene therapy.
