Hydrodynamic gene delivery to the pig liver via an isolated segment of the inferior vena cava

Abstract

Hydrodynamic gene delivery is an attractive option for non-viral liver gene therapy, but requires evaluation of efficacy, safety and clinically applicable techniques in large animal models. We have evaluated retrograde delivery of DNA to the whole liver via the isolated segment of inferior vena cava (IVC) draining the hepatic veins. Pigs (18-20 kg weight) were given the pGL3 plasmid via two programmable syringe pumps in parallel. Volumes corresponding to 2% of body weight (360-400 ml) were delivered at 100 ml s À1 via a Y connector. The IVC segment pressure, portal venous pressure, arterial pressure, electrocardiogram (ECG) and pulse were monitored. Concurrent studies were performed in rats for interspecies comparisons. The hydrodynamic procedure generated intrahepatic vascular pressures of 101-126 mm Hg, which is B4 times higher than in rodents, but levels of gene delivery were B200-fold lower. Suprahepatic IVC clamping caused a fall in arterial pressure, with the development of ECG signs of myocardial ischaemia, but these abnormalities resolved rapidly. The IVC segment approach is a clinically acceptable approach to liver gene therapy. However, it is less effective in pigs than in rodents, possibly because of larger liver size or a less compliant connective tissue framework.

DNA delivery to ‘ex vivo’ human liver segments

“…To avoid this adverse effect, we have described a retrograde cathetermediated gene delivery procedure 5 with the aim of locally reproducing the intrahepatic conditions mediated by tail vein hydrodynamic injection. However, all the studies reported in pigs 4,5,[11][12][13][14] and in human clinical trials 3 indicate that the efficiency of the procedure remains several orders of magnitude lower than observed in mice. 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.…”

Technical requirements for effective regional hydrodynamic gene delivery to the left lateral lobe of the rat liver

“…This creates potentially important pressure conduits at the periphery of the targeted liver segment. 13 One must also remember that other factors might influence the susceptibility to hydrodynamic gene delivery, in particular species differences in liver compliance (elasticity) 9,13 and size of the sinusoidal fenestrae. 16 This new technique provides highly specific regional hydrodynamic gene delivery to the liver in the rat, with minimum physiological disturbance.…”

“…The technique involves the rapid injection of large volumes of DNA solution into a peripheral (usually the tail) vein, using volumes amounting to B10% of the body weight in mice (B2.5 ml) 1,2 and B8-10% of body weight in rats (B20-25 ml). 3,4 However, although there have been six published reports in the pig [5][6][7][8][9][10] and one clinical trial, 11 none of these has provided levels of gene delivery remotely close to those seen in mice and rats. In the pig studies, levels of reporter gene expression were o1% of those in concurrent studies in rodents, while there was no substantive evidence for gene expression in the clinical study.…”

“…We have previously discussed in detail that swelling of the liver can occur only if there is raised intrahepatic vascular pressure, and that raised vascular pressure can occur only if there is resistance to flow. 9,13 We have proposed that the simplicity of the tail vein approach rests on the fact that nature has provided the necessary outflow obstruction, in that flow of DNA solution from the inferior vena cava (IVC) into the low-pressure portal vein is then obstructed by the vascular resistance of the capillary bed of the gut. 13 We have argued that when hydrodynamic delivery is targeted to individual lobes/segments of the liver (regional hydrodynamic gene delivery), outflow obstruction will need to be provided surgically.…”

Advances in Gene Delivery Systems

“…Similar studies have been reported by several groups using pigs as an animal model. [172,[182][183][184] A computercontrolled injection device has been developed for hydrodynamic gene delivery in large animals. [185] Using this system, Suda and colleagues [185] have reported safe and efficient gene delivery in pig liver, kidney and muscle.…”