Liver-targeted hydrodynamic gene therapy: Recent advances in the technique

Abstract

One of the major research focuses in the field of gene therapy is the development of clinically applicable, safe, and effective gene-delivery methods. Since the first case of human gene therapy was performed in 1990, a number of gene-delivery methods have been developed, evaluated for efficacy and safety, and modified for human application. To date, viral-vector-mediated deliveries have shown effective therapeutic results. However, the risk of lethal immune response and carcinogenesis have been reported, and it is still controversial to be applied as a standard therapeutic option. On the other hand, delivery methods for nonviral vector systems have been developed, extensively studied, and utilized in in vivo gene-transfer studies. Compared to viral-vector mediated gene transfer, nonviral systems have less risk of biological reactions. However, the lower gene-transfer efficiency was a critical hurdle for applying them to human gene therapy. Among a number of nonviral vector systems, our studies focus on hydrodynamic gene delivery to utilize physical force to deliver naked DNA into the cells in the living animals. This method achieves a high gene-transfer level by DNA solution injections into the tail vein of rodents, especially in the liver. With the development of genome editing methods, in vivo gene-transfer therapy using this method is currently the focus in this research field. This review explains the method principle, efficiency, safety, and procedural modifications to achieve a high level of reproducibility in large-animal models.

Keywords: Gene therapy; Hydrodynamic gene delivery; Image-guided; Liver; Non-viral.

Figure 1

Image-guided, computer-controlled hydrodynamic gene-delivery to the dog liver. The balloon catheter was placed at the appropriate position in the hepatic veins of right lateral lobe and the occlusion of the blood flow by the balloon was confirmed by injecting a small amount of contrast medium into the hepatic vein. Then the hydrodynamic injection of naked DNA solution was performed under the real time monitoring of liver structure by the laparoscope using the computer-controlled injection system (A). B: Time-pressure curve and the volume of injected solution recorded in the injection system. Solid and dotted lines represent actual and preloaded time-pressure curves. A gray area shows cumulative volume of injected saline (mL). C: Laparoscopic findings of the hydrodynamically injected right lateral lobe of the dog. The injected lobe was swollen and the injected DNA solution transiently made the liver pale. No destruction nor bleeding were seen on the surface of the liver (arrowheads). D: The effect of lobe-specific hydrodynamic gene delivery of luciferase expressing plasmid. The immunohistochemical analyses showed positively stained cells in the injected right lateral lobe. No stained cells were found in non-injected left lateral lobe.

Figure 2

Scheme of computer-controlled injection system. The schema of the newly developed hydrodynamic gene-delivery system. This figure is partly reused and modified with updated information from Figure 1 in Ref [20] with their permission. IVC: Inferior vena cava; PV: Portal vein.