Noninvasive radiological imaging of pulmonary gene transfer and expression using the human sodium iodide symporter.
OBJECTIVE
In this study we investigated the application of the human sodium iodide symporter (hNIS) as a reporter gene to noninvasively image in vivo gene transfer and expression in lung tissue in real time.


METHODS
Human NIS-expressing adenoviruses (Ad-hNIS) or empty adenoviruses (Ad-Bgl II) were instilled into the lungs of Cotton rats via the nostrils. After 3, 10, and 17 days post infection, gamma camera scintigraphy with 99mTcO4- was performed to observe the distribution and duration of gene transfer. At 20 days after infection, reverse transcription polymerase chain reaction was performed to detect hNIS gene expression. Dual expressing vector Ad-hNIS-eGFP was used to detect transgene expression by fluorescence photomicroscopy in infected lung tissue. Positron emission tomography (PET) imaging of gene transfer to the lungs was performed using 124I- as tracer. Finally, hNIS transfer to a polarized human airway epithelial cell layer was evaluated by phosphorimaging.


RESULTS
Lungs in animals infected with Ad-hNIS were clearly visible on scintigraphy and PET scans, while those infected with Ad-Bgl II were undetectable. Lungs in Ad-hNIS infected animals could still be visualized at 17 days but were no longer detectable at 20 days. Fluorescence microscopy showed that lung tissue infected with Ad-hNIS-eGFP had significantly higher GFP signal intensity than that infected with Ad-Bgl II.


CONCLUSIONS
It is feasible to use the hNIS gene as a reporter gene to monitor the location, magnitude, and timing of expression of genes delivered during pulmonary gene therapy. The ability to noninvasively visualize gene expression tomographically in real time has significant translational implications in human gene therapy.
Niu
Gang
G
Free Radical and Radiation Biology Program, Department of Radiation Oncology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, B 180 Med Labs, Iowa City, IA 52242, USA.
Krager
Kimberly J
KJ
Graham
Michael M
MM
Hichwa
Richard D
RD
Domann
Frederick E
FE
D000818:Animals; D005240:Feasibility Studies; D020869:Gene Expression Profiling / Q000379:methods*; D005786:Gene Expression Regulation / Q000502:physiology*; D018014:Gene Transfer Techniques; D017930:Genes, Reporter; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000378:metabolism*; D015336:Molecular Probe Techniques; D049268:Positron-Emission Tomography / Q000379:methods*; D051381:Rats; D016205:Sigmodontinae; D027981:Symporters / Q000235:genetics* / Q000378:metabolism*; D014162:Transfection / Q000379:methods; D000099209:Sodium-Iodide Symporters
D027981:Symporters; D000099209:Sodium-Iodide Symporters