SPECT imaging of cardiac reporter gene expression in living rabbits

SPECT imaging of cardiac reporter gene expression in living rabbits 1 2 first-author 1 corresp Corresponding author. E-mail address: hzslxl @163.com Corresponding author. E-mail address: hzslxl @163.com hzslxl @163.com 1 1 1 1 Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology; Hubei Key Laboratory of Molecular Imaging of Hubei Province, Wuhan 430022, China Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology; Hubei Key Laboratory of Molecular Imaging of Hubei Province, Wuhan 430022, China Department of Nuclear Medicine, the Second Affiliated Hospital of Guangzhou Medical College, Guangzhou 510260, China Department of Nuclear Medicine, the Second Affiliated Hospital of Guangzhou Medical College, Guangzhou 510260, China This work is to demonstrate feasibility of imaging the expression of herpes simplex virus 1-thymidine kinase (HSV1-tk) reporter gene in rabbits myocardium by using the reporter probe 131 I-2’-fluoro-2’-deoxy-1-β- D - arabinofuranosyl-5-iodouracil ( 131 I-FIAU) and SPECT. Rabbits of the study group received intramyocardial injection of Ad5-tk and control group received aseptic saline injection. Two sets of experiments were performed on the study group. Rabbits of the 1 st set were injected with 131 I-FIAU 600 µCi at Day 2 after intramyocardial transfection of Ad5-tk in 1×10 9 , 5×10 8 , 1×10 8 , 5×10 7 and 1×10 7 pfu, and heart SPECT imaging was done at different hours. Rabbits of the 2 nd were transferred various titers of Ad5-tk (1×10 9 , 5×10 8 , 1×10 8 , 5×10 7 , 1×10 7 pfu) to determine the threshold and optimal viral titer needed for detection of gene expression. Two days later, 131 I-FIAU was injected and heart SPECT imaging was performed at 6, 24 and 48 h, before killing them for gamma counting of the hearts. Reverse transcription-polymerase chain reaction (RT-PCR) was used to verify the transferred HSV1-tk gene expression. Semi-quantitative analysis derived of region of interest (ROI) of SPECT images and RT-PCR images was performed and the relationship of SPECT images with ex vivo gamma counting and mRNA level were evaluated. SPECT images conformed 131 I-FIAU accumulation in rabbits injected with Ad5-tk in the anterolateral wall. The optimal images quality was obtained at 24~48 h for different viral titers. The highest radioactivity in the focal myocardium was seen at 6 h, and then declined with time. The threshold was 5×10 7 pfu of virus titer. The result could be set better in 1~5×10 8 pfu by SPECT analysis and gamma counting. ROI-derived semi-quantitative study on SPECT images correlated well with ex vivo gamma counting and mRNA levels from RT-PCR analysis. The HSV1-tk/ 131 I-FIAU reporter gene/reporter probe system is feasible for cardiac SPECT reporter gene imaging. The optimal Ad5-tk titer is 1~5×10 8 pfu and optimal imaging time is 24~48 h after transferred Ad5-tk in rabbit. The imaging of transgene expression in heart might be used for noninvasive imaging of gene therapy in cardiac diseases in human. Reporter gene Herpes simplex virus 1-thymidine kinase 2’-fluoro-2’-deoxy-1-β- D -arabinofuranosyl-5- iodouracil Single photon emission computed tomography Cardiac References Yla-Herttuala S , Markkanen J E , Rissanen T T . Thends Cardiovasc Med , 2004 , 14 : 295 - 300 . Thends Cardiovasc Med Brewster L P , Brey E M , Greisler H P . Adv Drug Deliv Rev , 2006 , 58 : 604 - 629 . Adv Drug Deliv Rev Urbain J L C . J Nucl Med , 2001 , 42 : 107 - 108 . J Nucl Med Dobrucki L W , Sinusas A J . Molecular Imaging , 2005 , 49 : 106 - 115 . Molecular Imaging Tjuvajev J G , Stockhammer G , Desai R , et al . Cancer Res , 1995 , 55 : 6126 - 6132 . Cancer Res Tjuvajev JG , Finn R , Watanabe K , et al . Cancer Res , 1996 , 56 : 4087 - 4095 . Cancer Res Haubner R , Avril N , Hantzopoulos PA , et al . Eur J Nucl Med , 2000 , 27 : 283 - 291 . Eur J Nucl Med Inubushi M , Joseph C , Sanjiv S , et al . Circulation , 2003 , 107 : 326 - 332 . Circulation Bengel F M , Anton M , Richter , et al . Circulation , 2003 , 108 : 2127 - 2133 . Circulation Wen B , Burgman P , Zanzonico P , et al . Eur J Nucl Mol Imaging , 2004 , 31 : 1530 - 1538 . Eur J Nucl Mol Imaging Simoes M V , Miyagama M , Reder S , et al . J Nucl Med , 2005 , 46 : 98 - 105 . J Nucl Med Bengel F M , Anton M , Avril N , et al . Circulation , 2000 , 102 : 948 - 950 . Circulation Pislaru S , Janssens S P , Gersh B J , et al . Circulation , 2002 , 106 : 631 - 636 . Circulation Wu J C , Inubushi M , Sundaresan G , et al . Circulation , 2002 , 106 : 180 - 183 . Circulation 10.13538/j.1001-8042/nst.20.170-176 Supported by National Natural Science Foundation of China (No.30400176, 30571816) 2009-01-06 2009-06-20 2021-01-19 2009 Nuclear Science and Techniques 03 20