We evaluated the transfection efficiency of five different cationic liposom
e/plasmid DNA complexes, during the in vitro gene transfer into human epith
elial tracheal cell lines. A dramatic correlation between the transfection
efficiency and the charge ratio (positive charge of liposome to negative ch
arge of DNA) has been found. DC-Chol-DOPE was found to be the most effectiv
e liposome formulation. Therefore, a morphological and structural analysis
of DC-Chol-DOPE liposomes and DC-Chol-DOPE/DNA complexes, has been performe
d by transmission electron microscopy (TEM) and by confocal laser scanning
microscopy (CLSM), respectively. The process of interaction between DC-Chol
-DOPE/DNA complexes and human epithelial tracheal cells has been studied by
CLSM. These results raise some issues for in vivo gene therapy. (C) 1999 E
lsevier Science B.V. All rights reserved.