Improving plasmid DNA-mediated liver gene transfer by prolonging its retention in the hepatic vasculature.
BACKGROUND
Naked DNA is the simplest and safest method to deliver genes to the liver. In this study, we demonstrate that significant gene expression could be achieved in the liver by transiently restricting blood flow through the liver immediately following peripheral intravenous injection of plasmid DNA.


METHODS
Mice were intravenously (tail vein) injected with plasmid DNA in 100 microl of saline (0.9% NaCl) immediately followed by 8 s of occlusion of blood flow through the liver. The occlusion of blood flow was performed by using a clip at either the vena cava (VC) or at the portal vein and hepatic artery (PV+HA). Alternatively, the VC was clamped for 4 s followed by clamping the PV+HA for 4 s (VC and PV+HA).


RESULTS
Gene transfer to the liver was completed after blood flow through the liver was blocked for as short as 1 s. Up to 560 pg of luciferase protein per mg of extracted protein was observed from the liver after a single injection of 80 microg of plasmid DNA. Gene expression was increased more than 50-fold by the combination of clamping and electroporation.


CONCLUSIONS
This is the first demonstration of gene transfer to the liver via systemic administration without using any carrier system or physical force. Also, the technique provides new insights into the mechanism of hepatic gene transfer.
Liu
F
F
Center for Pharmacogenetics, School of Pharmacy, University of Pittsburgh, PA 15213, USA. fliu+@pitt.edu
Huang
L
L
D000818:Animals; D018274:Electroporation / Q000379:methods*; D015870:Gene Expression; D018014:Gene Transfer Techniques; D007275:Injections, Intravenous; D008099:Liver / Q000098:blood supply / Q000378:metabolism*; D008156:Luciferases / Q000032:analysis / Q000235:genetics; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D010957:Plasmids / Q000008:administration & dosage / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D013997:Time Factors; D001616:beta-Galactosidase / Q000235:genetics
D008156:Luciferases; D001616:beta-Galactosidase