title: Imaging pulmonary gene expression with positron emission tomography.
abstract: We evaluated positron emission tomographic imaging of pulmonary transgene expression, using an enhanced mutant herpes simplex virus-1 thymidine kinase as the reporter gene, in the lungs of normal rats. Sixteen rats were studied 3 days after an intratracheal administration of 5 x 10(9) to 1 x 10(11) viral particles of a replication-incompetent adenovirus containing a fusion gene of the mutant kinase and green fluorescent protein. Three rats infected with adenovirus containing no insert (null vector) served as control subjects. Images were obtained 1 hour after an intravenous injection of 9-(4-[18F]-fluoro-3-hydroxymethylbutyl)guanine, an imaging substrate for the viral kinase. After euthanasia, tissue radioactivity was determined in a gamma counter, and thymidine kinase activity and green fluorescent protein levels were measured in lung tissue samples. Imaging and gamma counting radioactivity measurements were strongly and linearly correlated (r2 = 0.96, p < 0.001). Imaging detected thymidine kinase expression above background (null vector) in 15 of 16 rats, even at low viral doses that produced little to no measurable green fluorescent protein expression. Lung 9-(4-[18F]-fluoro-3-hydroxymethylbutyl)guanine uptake (as assessed by imaging) correlated with in vitro assays of both kinase activity (r(2) = 0.48, p < 0.001) and fluorescent protein (r(2) = 0.46, p < 0.001). We conclude that positron emission tomographic imaging is a sensitive and quantitative method for detecting pulmonary reporter gene expression noninvasively.
authors.affiliation: Washington University School of Medicine, 660 South Euclid, St. Louis, MO 63110, USA.
authors.forename: Jean-Cristophe
authors.initials: JC
authors.lastname: Richard
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Zhou
authors.forename: Datta E
authors.initials: DE
authors.lastname: Ponde
authors.forename: Carmen S
authors.initials: CS
authors.lastname: Dence
authors.forename: Philip
authors.initials: P
authors.lastname: Factor
authors.forename: Paul N
authors.initials: PN
authors.lastname: Reynolds
authors.forename: Gary D
authors.initials: GD
authors.lastname: Luker
authors.forename: Vijay
authors.initials: V
authors.lastname: Sharma
authors.forename: Tom
authors.initials: T
authors.lastname: Ferkol
authors.forename: David
authors.initials: D
authors.lastname: Piwnica-Worms
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Schuster
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D004797:Enzyme-Linked Immunosorbent Assay; D019788:Fluorodeoxyglucose F18; D015870:Gene Expression / Q000235:genetics*; D018014:Gene Transfer Techniques; D017930:Genes, Reporter / Q000235:genetics*; D015316:Genetic Therapy / Q000379:methods; D006147:Guanine / Q000031:analogs & derivatives*; D018259:Herpesvirus 1, Human / Q000201:enzymology* / Q000235:genetics*; D016018:Least-Squares Analysis; D008168:Lung / Q000473:pathology*; D008171:Lung Diseases / Q000473:pathology / Q000628:therapy; D023421:Models, Animal; D019275:Radiopharmaceuticals; D051381:Rats; D017207:Rats, Sprague-Dawley; D013937:Thymidine Kinase / Q000235:genetics*; D013997:Time Factors; D014055:Tomography, Emission-Computed / Q000379:methods* / Q000592:standards; D019076:Transgenes / Q000235:genetics*; D016896:Treatment Outcome
chemical_list: C113308:9-(4-fluoro-3-hydroxymethylbutyl)guanine; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D006147:Guanine; D013937:Thymidine Kinase