Development of Catheter-Based Procedures for Transducing the Isolated Rabbit Liver with Plasmid DNA

Abstract

Rapid systemic injection of naked plasmid DNA (pDNA) in a large volume into a mouse tail vein has been shown to result in a high level of gene expression in the liver. However, the potential therapeutic benefit to humans embodied in hydrodynamic transfection of the liver cannot be realized until a clinically viable method for gene delivery is developed. In light of this fact, we have devised and evaluated several methods for delivering pDNA to the isolated rabbit liver using minimally invasive catheter-based techniques. Using a lobar technique, pDNA was delivered hydrodynamically to an isolated hepatic lobe using a balloon occlusion balloon catheter to occlude a selected hepatic vein. A whole organ technique was used wherein the entire hepatic venous system was isolated and the pDNA solution injected hydrodynamically into the vena cava between two balloons used to block hepatic venous outflow. Lobar delivery of a plasmid encoding a secreted alkaline phosphatase (SEAP) reporter gene resulted in significant levels of transgene product in the serum. A nonsecreted transgene product, chloramphenicol acetyltransferase (CAT), showed the highest levels of expression in the injected lobe distal to the injection site. Compared to lobar delivery, whole organ delivery yielded much higher serum levels of SEAP expression and a significantly broader hepatic parenchymal distribution of CAT expression. These preliminary studies suggest that catheter-mediated hydrodynamic delivery of pDNA to the isolated liver may provide a method for human gene therapy that is both therapeutically significant and clinically practicable.

DNA delivery to ‘ex vivo’ human liver segments

“…The exact reason for the low gene transfer efficiency of retrograde injection is still unknown, but the low resistance of the sinusoid bed must be a very important factor, as DNA can easily travel across the liver segment after hepatic vein injection, reaching the portal vein and then freely returning to the inferior cava vein through another liver segment. 15 In the present work, we hypothesize that human 'ex vivo' liver segments must be excellent candidates for anadromous gene transfer, as the outflow of injected DNA solution from the targeted segment is blocked in the surgical removal process. In all cases, vascular patency before injection was confirmed by contrast injection and X-ray fluoroscopy.…”

Advances in Gene Delivery Systems

“…[171,176,180] In an attempt to apply this simple procedure of gene delivery to the clinic, efforts have been made to reduce the total injection volume. Eastman et al [181] demonstrated in rabbits that a volume of 15 mL/kg can be safely injected into an isolated rabbit liver. Similar studies have been reported by several groups using pigs as an animal model.…”

Minimally invasive and selective hydrodynamic gene therapy of liver segments in the pig and human

“…In vivo study: pigs Initial porcine work aimed to reproduce that of Eastman et al, 8 where in the rabbit model, isolation of the hepatic veins was achieved surgically via the open abdomen. To develop a less invasive technique, presently available balloon catheters were used to isolate the liver.…”

“…Therefore, a method where the rapid fluid shifts were isolated to the liver to minimize the systemic upset was developed in the larger animal model of the rabbit. 8 The technique involved isolation of the inferior vena cava (IVC) at laparotomy and injection of pDNA solution between two balloon catheters within the IVC thereby isolating the liver venous outflow. A number of groups are now modifying this approach to HGT in the pig using balloon catheters to isolate the venous outflow of the liver.…”