Histidylated polylysine as a synthetic vector for gene transfer into immortalized cystic fibrosis airway surface and airway gland serous cells

Background We recently designed a cationic polymer called histidylated poly lysine made of polylysine partially substituted with histidyl residues whic h become protonated at slightly acidic pH. This polymer is thought to induc e the leakage of acidic vesicles containing plasmid/histidylated polylysine complexes. Methods and results Here, we have analyzed the ability of histidylated poly lysine to transfer reporter or CFTR genes into immortalized cystic fibrosis airway surface epithelial cells (Sigma CFTE29o- cells) and airway gland se rous cells (CF-KM4 cells) which are both important targets far cystic fibro sis gene therapy. The luciferase reporter gene expression measured after ge ne transfer with histidylated polylysine into both cell lines was quite hig h and similar to that obtained with commercially available vectors. In addi tion, the level of expression was not dependent on the presence of a membra ne disrupting agent such as chloroquine. Histidylated complexes were presen t in slightly acidic non-lysosomal cellular compartments as shown by a cyto logical approach using biotinylated plasmid, lysosome-specific antibodies a nd confocal microscopy. Histidylated complexes appeared to be of small size when prepared at low ionic strength and formed aggregates upon increasing the ionic strength. However, aggregate formation was prevented by the addit ion of 10% fetal bovine serum. Gene transfer efficiency varied with the siz e of the complexes and decreased when small particles were used. Conclusions These results suggest that histidylated polylysine may be an ef ficient non-viral vector for gene transfer into cystic fibrosis airway surf ace epithelial cells and airway gland serous cells. Copyright (C) 2000 John Wiley & Sons, Ltd.