No Immune Reaction

When Pam Davis of Case Western University School of Medicine tried the technique on mice with cystic fibrosis, she found the replacement gene was expressed in nasal lining and partially restored function - with little or no immune reaction. But that does not mean the method will work in people, she warns, because mice have a very different airway structure.

Indeed, there have already been many failed attempts to treat cystic fibrosis with gene therapy. Lungs are especially challenging, says respiratory specialist Duncan Geddes of Imperial College, London, because the lung lining is designed to keep out foreign objects. The build-up of thick sputum in the lungs of cystic fibrosis patients makes the problem even worse.

But the replacement gene only needs to be expressed in a small proportion of cells, Geddes says. "It's extremely interesting and promising."