Calorimetry of Cationic Liposome–DNA Complex and Intracellular Visualization of the Complexes

Abstract

This chapter describes cationic liposome–mediated gene transfer that has become a widely used tool for in vitro transfection of eukaryotic cells and as a promising and safe alternative for in vivo gene therapy applications. It involves the formation of a cationic lipid–DNA complex that interacts efficiently with the cell surface, leading to the entry and expression of the exogenous DNA. The use of cationic lipids as DNA delivery systems for gene therapy is limited by the relatively low efficiency of the gene transfer process compared with viral vectors. Improvement of the in vitro and in vivo cationic lipid–mediated gene transfection efficiency can be attempted by use of trial and error approaches consisting of synthesizing and testing a large number of cationic lipid derivatives. Alternatively, a deeper understanding of the intermediate steps and mechanisms involved in the gene transfer process mediated by cationic lipids could allow the design of new rational strategies to improve the transfection efficiency. Two key steps are involved in the cationic lipid–mediated gene transfer process: (1) interaction between the cationic liposomes and DNA leading to the formation of a complex and (2) interaction between the complex and the target cells leading to DNA entry and expression of the transgene.