Cationic liposomes enhance retrovirus-mediated multinucleated cell formation and retroviral transduction

A retroviral vector carrying herpes simplex virus thymidine kinase (HSV-TK) gene was introduced into Ψ2 packaging cells (Ψ2tkn) and XC tumor cells (XCtkn). Ψ2tkn, XCtkn and XC cells co-cultured with TK-carrying cells were killed by ganciclovir (GCV) treatment. The growth of XC cells transplanted into nude mice was also suppressed by intratumoral injection of Ψ2tkn or XCtkn cells and subsequent GCV administration. In addition, the XC cells cultured with either Ψ2tkn cells or cell-free retrovirus suspension formed giant multinucleated cells. The multinucleated cell formation was specific to the combination of XC cells and the retrovirus produced by the Ψ2tkn cells. Cationic liposomes enhanced the retrovirus-induced multinucleated cell formation and retroviral transduction. The correlation between the two actions of liposomes suggests that liposomes which enhance multinucleated cell formation are potent enhancers of retroviral transduction.