In vivo molecular imaging characterizes pulmonary gene expression during experimental lung transplantation.
Experimental gene therapy is a promising strategy to prevent ischemia-reperfusion (I/R) injury and allograft rejection after lung transplantation, and methods will eventually be needed to characterize pulmonary transgene expression in vivo in humans. Therefore, we studied positron emission tomography (PET) as a means of performing in vivo molecular imaging in rodent models of lung transplantation. Rats were transfected endotracheally with adenovirus encoding a fusion gene of a mutant Herpes simplex virus-1 thymidine kinase and the green fluorescent protein gene (the former serving as an imaging reporter gene). Twenty-four hours after transfection, lungs were transplanted in groups representing normal transplantation, I/R injury and acute allograft rejection. Imaging was obtained either 24 h after transplantation to study reperfusion injury or 4 days after transplantation to study graft rejection. After imaging, lungs were excised and analyzed for thymidine kinase activity. Imaging detected transgene expression in transplanted lungs even in the presence of acute rejection or I/R injury. The PET imaging signal correlated with in vitro lung tissue assays of thymidine kinase activity (r(2) = 0.534). Thus, noninvasive molecular imaging with PET is a feasible, sensitive and quantitative method for characterizing pulmonary transgene expression in experimental lung transplantation.
Dharmarajan
Sekhar
S
Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, USA.
Hayama
Makio
M
Kozlowski
James
J
Ishiyama
Takaaki
T
Okazaki
Mikio
M
Factor
Phillip
P
Patterson
G Alexander
GA
Schuster
Daniel P
DP
D000818:Animals; D015870:Gene Expression / Q000235:genetics*; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods; D006084:Graft Rejection / Q000000981:diagnostic imaging* / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics; D006147:Guanine / Q000031:analogs & derivatives; D018259:Herpesvirus 1, Human / Q000201:enzymology; D008168:Lung / Q000000981:diagnostic imaging* / Q000378:metabolism*; D016040:Lung Transplantation; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D051381:Rats; D011914:Rats, Inbred BN; D011916:Rats, Inbred F344; D015427:Reperfusion Injury / Q000000981:diagnostic imaging* / Q000378:metabolism; D013937:Thymidine Kinase / Q000235:genetics; D013997:Time Factors; D016896:Treatment Outcome
C113308:9-(4-fluoro-3-hydroxymethylbutyl)guanine; D019275:Radiopharmaceuticals; D049452:Green Fluorescent Proteins; D006147:Guanine; D013937:Thymidine Kinase