Restoration of bacterial killing activity of human respiratory cystic fibrosis cells through cationic vector-mediated cystic fibrosis transmembrane conductance regulator gene transfer

In vitro and in vivo studies have demonstrated that gene transfer of the CF TR (cystic fibrosis transmembrane conductance regulator) cDNA into human re spiratory cells through nonviral vectors can occur safely and can be done r epeatedly. Although functional evaluation of CFTR in cystic fibrosis (CF) p atients enrolled in phase I clinical trials using cationic liposomes has sh own a partial correction of nasal potential difference, a biological assay indicating a therapeutic relevance of CFTR gene transfer is still missing. Our aims were to study the induction of killing activity toward Pseudomonas aeruginosa (PA) in CF cells by cationic vector-mediated CFTR gene transfer and to use this assay as a therapeutic end point. Luciferase expression an d GFP FACS analysis were used to evaluate the optimal vector and the effici ency of gene transfer into non-CF human respiratory cells growing from nasa l polyp explants at the air-liquid interface, To prove that transgenic CFTR was expressed in CF cell cultures under the same experimental conditions, a specific RT-PCR was performed. Challenge of the outgrowths with a known a mount of PA showed a bacterial clearance activity by non-CF respiratory cel ls, while in the case of CF cells it even resulted in bacterial growth. Cat ionic vector-mediated CFTR cDNA determined the recovery of bacterial cleara nce activity only under those conditions yielding 5% or more of GFP-positiv e cells, The results shown in this study might be helpful in considering ca tionic vectors as therapeutic nonviral vectors for transferring CFTR into h uman CF respiratory cells, as well as for restoring the bacterial killing a ctivity defective in cystic fibrosis.