Cystic fibrosis (CF) is the most common life-threatening inherited disease in the Caucasian population. It is caused by genetic defects in the cystic fibrosis transmembrane conductance regulator gene (CFTR). CFTR encodes for a cAMP-regulated chloride channel located in the apical membrane of polarized epithelial cells. The most frequent mutation, δF508, impairs the maturation and functional CFTR expression. As a new therapeutic approach, this study investigates the restoration of CFTR transport and regulatory function by transfection of human cells with optimized wildtype (wt) CFTR-mRNA.

We used human airway epithelia cell lines (CFBE41o^- and 16HBE14o^-) to establish the general mechanism. We carried out transepithelial measurements to demonstrate the restoration of CFTR function. In Ussing chamber experiments we showed an increased CFTR current following cAMP activation (74%) after transfection of CF-cells with wtCFTR-mRNA compared to untransfected cells. This current appeared to be almost identical to the current of control cells expressing wtCFTR (16HBE14o^-). In addition, biochemical and immunofluorescence techniques showed a considerably increased CFTR protein amount in the apical membrane after mRNA transfection of CF-cells.

To transfer these data into a relevant physiological context we performed transepithelial measurements using wtCFTR-mRNA transfected primary cultured human nasal epithelial (HNE) cells. We could demonstrate a 10-fold increase in CFTR current after cAMP application compared to the controls. This current increase could also be inhibited by the specific CFTR blocker CFTRinh172.

In conclusion, our data demonstrate that CFTR-mRNA transfection of CF airway epithelia may serve as a novel concept for the treatment of CF.