Cystic Fibrosis (CF) is caused by a mutation of the cystic fibrosis transmembrane conductance regulator (CFTR), a Cl^- channel in the apical membrane of airway epithelial cells. The most common mutation ࢞F508 leads to an impaired processing, following degradation of the protein, preventing the functional expression of the CFTR channel.

In this study we transfected human CF airway epithelial cells (CFBE41o^-) with wild type (wt) CFTR-mRNA to investigate the insertion and functional expression of CFTR into the apical membrane. Therefore, we carried out Ussing chamber measurements to demonstrate the restoration of CFTR function and in parallel performed protein biochemical experiments to verify the increase of CFTR protein amount in the apical plasma membrane.

After transfection with wtCFTR-mRNA Ussing chamber experiments revealed an increased CFTR current following cAMP activation (74%) when compared to untransfected cells. This current appeared to be almost identical to the current of control cells expressing wtCFTR (16HBE14o^-). Furthermore, the CFTR activation was sensitive to the specific Cl^- channel blocker CFTRinh172, which decreased nearly 100% of the generated CFTR current and also reduced the electrophysiological parameters capacitance and conductance, significantly.

In addition, the protein biochemical approaches showed a markedly increased CFTR protein amount in the apical membrane. Using immunofluorescence techniques we demonstrated that the transfection of CFBE41o^- cells using wtCFTR-mRNA led to an increase of CFTR expression by about 220% in comparison to untransfected CFBE41o^- cells.

These data clearly indicate a successful restoration of impaired CFTR function in CF epithelia cells by transfection with wtCFTR-mRNA.