Many rare monogenic diseases are treated by
protein replacement
therapy, in which the missing
protein is repetitively administered to the patient. However, in several cases, the missing
protein is required at a high and sustained level, which renders
protein therapy far from being adequate. As an alternative, a gene
therapy treatment ensuring a sustained effectiveness would be particularly valuable. Liver is an optimal organ for the secretion and systemic distribution of a therapeutic transgene product. Cutting edge non-viral gene
therapy tools were tested in order to produce a high and sustained level of therapeutic
protein secretion by the liver using the hydrodynamic delivery technique. The use of S/MAR matrix attachment region provided a slight, however not statistically significant, increase in the expression of a reporter gene in the liver. We have selected the
von Willebrand Factor (vWF) gene as a particularly challenging large gene (8.4 kb) for liver delivery and expression, and also because a high vWF blood concentration is required for disease correction. By using the optimized miniplasmid pFAR free of antibiotic resistance gene together with the Sleeping Beauty transposon and the hyperactive SB100X
transposase, we have obtained a sustainable level of vWFblood secretion by the liver, at 65% of physiological level. Our results point to the general use of this plasmid platform using the liver as a
protein factory to treat numerous rare disorders by gene therapy.