In vivo Gentransfer nackter DNA in xenotransplantierte Kolonkarzinome in der Nude Maus mit Hilfe der Jet-Injektion

Abstract

Background: The jet-injection technology has developed to an applicable alternative to viral or liposomal gene delivery systems. In this study a novel “low-volume High-Speed Jet- Injector” system was used for the direct gene transfer of naked DNA into tumors. The versatile hand-held Jet-Injector uses pressurized air to force small volumes (1.5 – 7 µl) of naked DNA into targeted tissues. Methods: In our in vivo studies human colon carcinoma xenotransplanted female nude mice were jet-injected simultaneously with the β-galactosidase (LacZ) and the human tumor necrosis factor alpha (TNF-α) gene carrying vector plasmids. The animals received a total of ten jet-injections through the skin into the tumor at a pressure of 3.0 bar. The jet-injection delivered 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 6.0, or 7.0 µl plasmid DNA (1 µg/µl of each plasmid in water) into the tumor tissue. Forty-eight hours after jet-injection, tumors were excised and cryosectioned for LacZ or TNF-α detection. Results The jet-injection of DNA leads to a spread expression pattern within tumor tissues with penetration depths of 5 – 10 mm. The X-Gal staining in cryosections of jet-injected tumors revealed LacZ expression with moderate expression level at a injection volume of 1.5 to 2.5 µl and strong expression at injection volumes of 3 – 7 µl For the therapeutic gene TNF-α TNF-ELISA showed efficient expression and secretion of this cytokine within the tumor tissue after jet-injection. Conclusions: These studies demonstrate the applicability of the Jet-Injection technology for the efficient and simultaneous in vivo gene transfer of two different plasmid DNAs into tumors. It can be employed for non-viral gene therapy of cancer using minimal amounts of naked DNA.