Diagram 1 : Gene Therapy for Cystic Fibrosis 
AIRWAY BLOOD 
Normal 
mucous 
Airway epithelial cell with 
functional CFTR protein 
pumps chloride in airway. 
Water follows the chloride, 
leading to thin mucous. 
Thick, dry 
mucous 
s ■ ; 
Mutant! 
CFTR# 
Airway epithelial cell with 
non-functioning CFTR protein 
cannot pump chloride into 
airway. Water remains in 
cell, leading to thick, dry 
mucous. 
Normal 
mucous 
Airway epithelial cell following 
gene therapy with AAV-CFTR 
vector. Functional CFTR protein 
pumps chloride into airway. 
Water follows the chloride, 
leading to thin mucous. 
Recombinant DNA Research, Volume 20 
