1. ¹Department of Surgery, School of Medicine, Keio University, Tokyo, Japan
2. ²Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan
3. ³Faculty of Engineering, Kobe University, Kobe, Hyogo, Japan
4. ⁴Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan
5. ⁵Department of Pathology, School of Medicine, Keio University, Tokyo, Japan

Correspondence: Dr M Ueda, Department of Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan. E-mail: m_ueda@sc.itc.keio.ac.jp

Received 19 December 2005; Revised 18 June 2006; Accepted 19 August 2006; Published online 22 September 2006.

Abstract

The development of safe and efficient liver-specific gene delivery approaches offers new perspectives for the treatment of liver disease, in particular, liver cancer. We evaluated the therapeutic potential of hepatotropic nanoparticles for gene therapy of liver tumor. These nanoparticles do not contain a viral genome and display the hepatitis B virus L antigen, which is essential to confer hepatic specificity. It has not been shown whether a therapeutic effect could be obtained using L nanoparticles in a human liver tumor xenograft model. Rats bearing human hepatic (NuE) and non-hepatic tumors were injected with L nanoparticles containing a green fluorescent protein (GFP) expression plasmid. GFP expression was observed only in NuE-derived tumors but not in the non-hepatic tumor. The potential for treatment of liver tumors was analyzed using L nanoparticles containing the herpes simplex virus thymidine kinase gene, in conjunction with ganciclovir pro-drug administration. The growth of NuE-derived tumors in L particle-injected rats was significantly suppressed, but not of the non-hepatic tumor control. In summary, this is the first demonstration that nanoparticles could be used for delivery of therapeutic genes with anti-tumor activity into human liver tumors. This intravenous delivery system may be one of the major advantages as compared to many other viral vector systems.