[Myocardial single photon emission tomography imaging of reporter gene expression in rabbits].
OBJECTIVE
To explore the feasibility of single photon emission computed tomography (SPECT) detection of heart reporter gene expression and observed the optimal transfecting titer and imaging time by using herpes simplex virus 1-thymidine kinase (HSV1-tk) as reporter gene and 131I-2'-fluoro-2'-deoxy-1-beta-D-arabinofuranosyl-5-iodouracil (131I-FIAU) as reporter probe in rabbit myocardium.


METHODS
The recombinant Ad-tk carrying HSV1-tk gene and adenovirus (Ad) as vector was constructed and intramyocardially injected to rabbits at various concentrations (1 x 10(9) pfu, 5 x 10(8) pfu, 1 x 10(8) pfu, 5 x 10(7) pfu, 1 x 10(7) pfu). Two days later, rabbits were injected with 600 microCi 131I-FIAU in ear-margin vein and then underwent SPECT myocardium imaging for detection of HSV1-tk expression at 6 h, 24 h, 48 h and 72 h after injection, rabbits with 1 x 10(9) pfu Ad-tk injection were imaged at 96 h and 120 h. Rabbits were sacrificed after imaging and the total myocardial 131I-FIAU accumulation was quantified in percent of injected dose per gram myocardium (% ID/g). The myocardial Ad-tk expression was determined with RT-PCR.


RESULTS
Reporter gene was detected by SPECT imaging in the injection site while not detected in the control myocardium and site remote from injection. RT-PCR results also evidenced HSV1-tk express in the injection site. The SPECT target/nontarget ratio was correlated with ex vivo gamma-counting (r2 = 0.933, P<0.01) and expression of HSV1-tk (r2 = 0.877, P<0.01). Myocardial accumulation could be identified at viral titers as low as 1 x 10(7) pfu by SPECT imaging.


CONCLUSIONS
The cardiac SPECT reporter gene imaging with HSV1-tk as reporter gene and 131I-FIAU as reporter probe is feasible.
Liu
Ying
Y
Hubei Key Laboratory of Molecular Imaging, Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
Lan
Xiao-li
XL
Zhang
Liang
L
Wu
Tao
T
Jiang
Ri-feng
RF
Zhang
Yong-xue
YX
D000818:Animals; D005260:Female; D015870:Gene Expression; D018014:Gene Transfer Techniques; D017930:Genes, Reporter; D006321:Heart / Q000000981:diagnostic imaging*; D008297:Male; D009206:Myocardium / Q000378:metabolism; D011817:Rabbits; D013937:Thymidine Kinase / Q000235:genetics; D015899:Tomography, Emission-Computed, Single-Photon; D014162:Transfection; D014498:Uracil / Q000031:analogs & derivatives
D014498:Uracil; D013937:Thymidine Kinase; C048747:5-iodouracil