Recombinant DNA Advisory Committee - 12/3-4/92 
Dr. Welsh described data derived from in vitro and in vivo model systems. Production of 
mRNA and protein has been demonstrated in monkeys that already have the wild-type 
CFTR function. The AdCFTR vector has been evaluated in the nasal epithelium of 
monkeys and the lungs of cotton rats. He described experiments in which human CF 
airway epithelial cells were cultured on a permeable support in order to create an 
epithelium. The apex side of these cells is at the air/liquid interface and the basal side 
of the cells is down. CFTR function can be easily demonstrated in this model support 
system. When the epithelium grown on these permeable supports is exposed to the 
adenovirus vector and adenosine 3':5'-cyclic phosphate (cyclic AMP) agonists, the 
chloride secretion defect is corrected. Significant responses were observed at doses as 
low as a 0.1 MOI. The promoter is not a high level promoter, but CFTR is not 
expressed at high levels in these cells. 
Dr. Welsh described FACS analysis data regarding the percentage of cells that are 
corrected by this procedure. At 24 hours, little difference was observed between control 
and virus treated cells. At 48 hours, the number of positive cells (fluorescent cells) 
increased dramatically. The number of positive cells continued to increase for 96 hours. 
Data indicates that at an MOI of 10, gene expression was observed in 60 to 70% of the 
cells. FACS analysis of transduced cells obtained from the bronchioli of cotton rats 
demonstrated that the majority of the vector resides in the apical cells; however, 
occasional staining was observed in the basal cells. 
Dr. Welsh addressed the issue of safety. Experiments have been performed on a variety 
of tissue culture cell lines, primary cells, and in vivo. Gene transduction and protein 
expression have been observed in all instances. Viral mRNA synthesis was detected 
occasionally, suggesting that viral proteins can be made at a low level. Low level viral 
DNA synthesis was detected. There was minimal evidence of inflammation of cytopathic 
effects. The important issue is that in all of the in vitro and in vivo models tested, no 
evidence of virus replication was detected. 
Dr. Welsh responded to Dr. Ginsberg's specific questions regarding the cotton rat model. 
A dose of 4 x 10 10 PFU of Ad2/CFTR-1 were administered to these animals. This dose 
is approximately 1,000 times larger than the highest dose proposed for human 
administration. Gene expression was observed in all animals. The inflammatory 
response was monitored in these animals. Bronchial/alveolar lavage demonstrated no 
increase in cell number over control animals. 
Dr. Welsh responded to Dr. Post's comments regarding host cell protein shut-off and 
cytopathic effects. Host cell macromolecular synthesis is inhibited early in infection and 
cytopathic effects usually develop later. The host cell shut-off maps in part to Elb and 
cytopathic effects map in part to penton, which can be present in crude preparations. 
Host cell shut-off is not detected at an MOI of up to 200 with Ad2/CFTR-1 in HeLa 
Recombinant DNA Research, Volume 16 
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