Partial correction of endogenous ΔF508 CFTR in human cystic fibrosis airway epithelia by spliceosome-mediated RNA trans-splicing

Spliceosome-mediated RNA trans-splicing (SMaRT) was investigated as a means for functionally correcting endogenous Delta F508 cystic fibrosis transmembrane conductance regulator (CFTR) transcripts using in vitro human cystic fibrosis (CF) polarized airway epithelia and in vivo human CF bronchial xenografts. Recombinant adenovirus (Ad.CFTR-PTM) encoding a pre-therapeutic molecule (PTM) targeted to CFTR intron 9 corrected transepithelial cyclic AMP (cAMP)-sensitive short-circuit current (Isc) in Delta F508 homozygous epithelia to a level 16% of that observed in normal human bronchial epithelia. Molecular analyses using RTPCR and western blotting confirmed SMaRT-mediated partial correction of endogenous Delta F508 messenger RNA (mRNA) transcripts and protein. In an in vivo model of Delta F508 CIF airway epithelia, human CIF bronchial xenografts infected with Ad. CFTR-PTM also demonstrated partial correction of CFTR-mediated Cl- permeability at a level 22% of that seen in non-CF xenografts. These results provide functional evidence for SMaRT-mediated repair of mutant endogenous CFTR mRNA in intact polarized CIF airway epithelial models.