Monitoring the expression of therapeutic genes in targeted tissues in disease models is important to assessing the effectiveness of systems of gene therapy delivery. We applied a new light-detection cooled charged-coupled device (CCCD) camera for continuous in vivo assessment of commonly used gene therapy delivery systems (such as ex vivo manipulated cells, viral vectors, and naked
DNA), without the need to kill animals. We examined a variety of criteria related to real-time monitoring of
luciferase (luc) gene expression in tissues including bone, muscle, salivary glands, dermis, liver, peritoneum, testis, teeth, prostate, and bladder in living mice and rats. These criteria included determination of the efficiency of
infection/transfection of various viral and nonviral delivery systems, promoter specificity, and visualization of
luciferase activity, and of the ability of
luciferin to reach various organs. The exposure time for detection of luc activity by the CCCD camera is relatively short (approximately 2 minutes) compared with the intensified CCD camera photon-counting method (approximately 15 minutes). Here we transduce a variety of vectors (such as viruses, transfected cells, and naked
DNA) by various delivery methods, including electroporation, systemic injection of viruses, and tail-vein, high-velocity-high-volume administration of
DNA plasmids. The location, intensity, and duration of luc expression in different organs were determined. The distribution of
luciferin is most probably not a barrier for the detection of in vivo
luciferase activity. We showed that the CCCD photon detection system is a simple, reproducible, and applicable method that enables the continuous monitoring of a gene delivery system in living animals.