Intracellular trafficking of a plasmid complexed to glycosylated cationic polymers in cystic fibrosis human airway epithelial cells
Gene therapy represents a potential advance in the treatment of cystic fibrosis. Safe, efficient and non-toxic gene delivery vectors are needed to allow human clinical applications. The goal of this study was to identify the intracellular barriers to an efficient gene transfer by using cationic polymers in order to develop more efficient vectors. We first studied glycosylated polylysines (pLK), in which pLK condenses DNA and sugar-moieties allow a cell-specific uptake. We have shown that one major limiting step with this vector was a delayed exit from endosomes. Glycosylated polyethylenimines (PEI) have then been developed because PEI has an intrinsic endosomolytic activity. We have shown that lactosylated PEI allows the most efficient in vitro gene transfer into airway epithelial cells. Complexes are able to exit from endosomal vesicles and accumulate near the nucleus. In vivo studies in animals are under investigation. However, the nuclear uptake in quiescent cells remains a limiting step for gene transfer by using lactosylated PEI. Modifications of the plasmid are under study in order to improve this step.
Key words :cystic fibrosis, gene transfer, synthetic vectors, glycosylated cationic polymers, endocytosis, intracellular trafficking, confocal microscopy, electron microscopy