216. Enhancement of Gene Transfection Both In Vitro and In Vivo Using Polymer Conjugated HVJ-Envelope Vector

Vector development is critical for the advancement of human gene therapy. However, the use of viral vectors raises many safety concerns and most non-viral methods are less efficient for gene transfer. One of the breakthroughs in vector technology is the combination of the vector with various polymers. HVJ (hemagglutinating virus of Japan) envelope vector (HVJ-E) has been developed as a versatile gene transfer vector. In this study, we combined HVJ-E with cationized gelatin(CG) to make it a more powerful tool and assessed its transfection efficiency in vitro and in vivo. CG is one of the most suitable polymers for the complex formation with HVJ-E because of the positive charge and biocompatibility. As shown in Fig. 1, we combined it with HVJ-E and used it in vitro and in vivo experiments. In addition, we investigated the mechanism of the gene transfer by means of the inhibition of fusion or endocytosis. The combination of both protamine sulfate(PS) and CG with HVJ-E, referred to as PS-CG-HVJ-E, further enhanced the in vitro transfection efficiency. In CT26 cells, the luciferase gene expression of PS-CG-HVJ-E was approximately 10 times higher than that of the combination of PS with HVJ-E or the combination of CG with HVJ-E, referred to as PS-HVJ-E or CG-HVJ-E, respectively. In case of in vivo study, we tried intravenous administration at first. In conclusion, the luciferase gene expression in liver mediated by intravenous administration of CG-HVJ-E was much higher than the luciferase gene expression mediated by PS-HVJ-E or PS-CG-HVJ-E and approximately 100 times higher than that mediated by HVJ-E alone. Next, we tried intraperitoneal administration of CG-HVJ-E containing luciferase gene to the peritoneal disseminated colon tumor model mice. As shown in Fig. 2, the luciferase gene expression was specifically detected at tumor nodules. Thus, cationized gelatin-conjugated HVJ-E enhanced gene transfection efficiency both in vitro and in vivo. These results suggest that the conjugation with low molecular weight cationized gelatin may increase in vivo transfection efficiency of various recombinant viral vectors such as retrovirus, herpes virus and lentivirus vector.