Phosphonocationic lipids in protein delivery to mice lungs

Cationic liposomes constitute one of the main approaches currently investigated to introduce a gene with therapeutic properties into a cell. Another alternative consists in directly introducing the normal protein of concern to, for example, restore the deleted function. We report here on in vitro and in vivo results obtained with GLB73, one of the phosphonolipids investigated as gene transfer agents. In previous studies this cationic lipid had shown its DNA-transfer efficacy in vitro and in vivo. We also confirmed the feasibility of protein/cationic lipid delivery in epithelial cells of mice lungs after intratracheal administration by use of a reporter gene (beta-galactosidase). Two quantitative tests (i.e., a chemiluminescent assay and a flow cytometry assay) were used to determine the amount of beta-galactosidase found in the lungs and the percentage of transfected cells. They showed that 50% of the cells of mice lungs were still positive at day 4 after protein/GLB73 delivery. Immunohistochemistry and electron microscopy studies allowed us to determine the spatial distribution and visualize the penetration of our complex into the lungs.