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Imaging pulmonary gene expression with positron emission tomography.
Jean-Cristophe Richard1, Zhaohui Zhou, Datta E Ponde
1Washington University School of Medicine, 660 South Euclid, St. Louis, MO 63110, USA.
American Journal of Respiratory and Critical Care Medicine
|December 31, 2002
Summary
Positron emission tomographic imaging noninvasively detects pulmonary reporter gene expression in rats. This sensitive method accurately quantifies gene expression using viral thymidine kinase and a novel imaging substrate.
Area of Science:
- Molecular Imaging
- Gene Therapy
- Respiratory Medicine
Background:
- Reporter gene expression in the lungs is critical for gene therapy efficacy.
- Noninvasive monitoring of pulmonary transgene expression is needed.
Purpose of the Study:
- To evaluate positron emission tomographic (PET) imaging for detecting pulmonary transgene expression.
- To assess the sensitivity and quantitation of PET imaging using a herpes simplex virus-1 thymidine kinase reporter gene.
Main Methods:
- Rats received intratracheal administration of replication-incompetent adenovirus carrying a fusion gene (mutant kinase-green fluorescent protein).
- PET imaging was performed after intravenous injection of the imaging substrate 9-(4-[18F]-fluoro-3-hydroxymethylbutyl)guanine.
- Post-euthanasia, lung tissue radioactivity, thymidine kinase activity, and green fluorescent protein levels were measured.
Main Results:
- PET imaging and ex vivo gamma counting showed strong linear correlation (r2 = 0.96).
- PET detected thymidine kinase expression in 15 of 16 rats, even at low viral doses.
- Imaging-assessed gene expression correlated with in vitro kinase activity and fluorescent protein levels.
Conclusions:
- Positron emission tomographic imaging is a sensitive and quantitative tool for noninvasive monitoring of pulmonary reporter gene expression.
- This technique allows for accurate assessment of gene transfer and expression in the lungs.