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Gene Therapy (2006) 13, 16191627 & 2006 Nature Publishing Group All rights reserved 0969-7128/06 $30.00 www.nature.com/gt
ORIGINAL ARTICLE
Variability of naked DNA expression after direct local injection: the inuence of the injection speed
FM Andr1,2, C Cournil-Henrionnet1,2,3, D Vernerey4, P Opolon1,2 and LM Mir1,2
1CNRS, UMR 8121, Laboratory of Vectorology and Gene Transfer, Institut Gustave-Roussy, Villejuif, France; 2Univ Paris-Sud, UMR 8121, Laboratory of Vectorology and Gene Transfer, Institut Gustave-Roussy, Villejuif, France; 3UMR7561 CNRS, Universit de Nancy I, Vanduvre Ls Nancy, France and 4Biostatistics and Epidemiology Unit, Institut Gustave-Roussy, Villejuif, France
The simple injection of DNA into muscles is known to result in the expression of the injected genes, even though at low and variable levels. We report that this variability in DNA expression is partly dependent on the injection speed. The acceleration of the injection speed from values around 2 ml/s up to ones around 25 ml/s (depending on the tissue) results in a signicant increase in gene expression in skeletal muscle (280 times on an average) and in liver (50 times) and a nonsignicant sevenfold increase in tumors. Heparin, which inhibits the spontaneous uptake of the injected DNA, also inhibits the increases related to the injection speed. However, at the highest injection speed, this inhibition is not total
because very fast injections provoke a direct permeabilization of the cells. This hydroporation could be similar to the permeabilization found in the hydrodynamics method based on the fast intravascular injection of a huge volume of DNA.Neither the hydroporation nor the heparin-inhibitable uptake mechanism induces histologically detectable lesions. There is a limited muscle cell stress independent of the injection speed. Heterogeneity in the injection speed might thus be an explanation for the variability in DNA expression after simple injection.
Gene Therapy (2006) 13, 16191627. doi:10.1038/sj.gt.3302827; published online 27 July 2006
Keywords: non-viral gene therapy; muscle; liver; tumor; endocytosis; hydroporation
Introduction
Non-viral gene therapy approaches are being actively investigated. It has been proved that the simple injection of DNA into skeletal muscle can result in the expression of the injected gene, although at very low and variable levels.1 The crucial point that limited the use of this very simple procedure was the extreme variability of gene expression following DNA injection. Until now, the reasons for this variability have...