543. Monitoring Transgene Expression by Radio-Peptide Positron Emission Tomography

• Published in: Molecular therapy Vol. 13; no. S1; p. S209
• Main Authors: Gazdhar, Amiq, Bilici, Murat, Ayuni, Erick, Krause, Thomas, Hofmann, Michal, Schmid, Raplh A.
• Format: Journal Article
• Language: English
• Published: Milwaukee Elsevier Limited 01-05-2006
• Subjects: Efficiency; Gene therapy; Localization; Nanoparticles; Peptides; Thoracic surgery; Tomography; Switzerland
• ISSN: 1525-0016; 1525-0024
• DOI: 10.1016/j.ymthe.2006.08.615

Background Progress towards Clinical application of gene therapy is hindered by the lack of possibility to image and trace transgene expression. Optical methods using fluorescent gene products or chemiluminesce inducing enzymes are not fully quantitative because of tissue absorption and fluorescence quenching. By using radioactive probes such as positron emitter labelled radiopeptides, a quantitative method for measuring transgene expression would be available. Aim The feasibility of electroporation mediated gene transfer of human somatostatin receptor 2 (hsstr2) in rats and subsequent PET/CT imaging was evaluated. Methods100 μg of Pcik-hSSTR2 plasmid was injected in the forelimb muscle of anesthetised adult male Fischer rats (n = 12) followed by in vivo electroporation with 4, 20ms pulses of 200v/cm. Assessment was performed at 24 hrs after gene transfer and repeated at different time points till day 6. 2-5MBq of Ga-68-DOTATOC (0.5nmol DOTATOC peptide) was injected via the penile vein.30 minutes after injection, PET/CT Siemens/CTI,Erlangen/Knoxville;LSO Biograph16-pico3D High res,4.0mm intrinsic resolution)scans were performed (10min emission). After reconstruction, segmentation, attenuation and scatter correction of the PET/CT, activity accumulations were measured in the right and left fore limb of the rats. Results All the animals showed moderate to high accumulation of radioactivity in the right fore limb. No significant activity accumulation was found in the contralateral muscles. Correct CT anatomical co registration into the forelimb muscle was found for all animals. Relative expression was found to be increased by a factor of 3-8 as correlated to the contralateral activity. Induction of expression increased by a factor of 2-4 at 24hrs and 48hrs after gene transfer. No activity accumulation could be detected in the forelimbs 6 days after gene transfer. Conclusion Expression of hsstr2 as reporter gene may be detected and quantified by PET/CT.