Somatic Cell Gene Transfer 
airway. Using antibody and RNA probes, we have 
characterized the distribution of CFTR expres- 
sion in the human bronchus. The airway epithe- 
lial cells express low levels of CFTR. The predom- 
inant site of expression, however, is in the 
submucosal glands that are responsible for the 
production and delivery of mucus to the airway 
lumen. These findings suggest that effective gene 
therapies may require genetic reconstitution in 
both the epithelium and the submucosal glands. 
This work is also supported by the Cystic Fibrosis 
Foundation. 
We have entered a new phase of the develop- 
ment of CF gene therapies in which approaches 
for delivering functional CF genes into airway 
cells in vivo are being designed and tested. Di- 
rect inhalation of the gene transfer substrates 
could provide a noninvasive way of delivering 
the genes to the appropriate cells. Several viral 
and nonviral approaches are being considered. 
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