Myocardial Kinetics of Reporter Probe 124I-FIAU in Isolated Perfused Rat Hearts After In Vivo Adenoviral Transfer of Herpes Simplex Virus

Reporter gene imaging holds promise for noninvasive monitor-ing of cardiac gene therapy. We recently demonstrated that 124I-labeled 2-fluoro-2-deoxy-5-iodo-1-D-arabinofuranosyl-uracil (124I-FIAU) is suitable for PET of myocardial expression of herpes simplex virus type 1 thymidine kinase reporter gene (HSV1-tk). In contrast to previous studies in tumors, early spe-cific uptake was followed by rapid washout. Myocardial kinetics of 124I-FIAU are still poorly understood. This study aimed at a further investigation under controlled conditions using an iso-lated heart perfusion model. Methods: Male Wistar rats under-went transthoracic regional injection of replication-defective ad-enovirus (2.5 109 plaque-forming units) containing either HSV1-tk (n 16) or LacZ reporter gene (n 15) into the inferior wall. Nonmanipulated rats (n 5) served as further controls. Hearts were excised 2 d later and perfused according to th