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.
Bibliographical noteFunding Information:
We thank Hilla Giladi (Gene Therapy Institute, Hadassah Medical Center) for useful advice during the experimental work and preparation of the manuscript; Jonathan Axelrod (Liver Unit, Hadassah Medical Center) for help; and Eitan Yaffe Nof, Yinon Ben-Neriah, and Iris Lavon (all from the Department of Immunology, Hebrew University, Hadassah Medical Center) for their animal model. Mark Christenson and Sten Tomegard (both from Roper Scientific, Inc.) continuously supported this work. The Berkowitz Family Foundation supported this study. E.G. holds the Sam and Ellie Fishman Chair in Gene Therapy. We acknowledge the Hamamatsu Photonics Corporation and their representatives in Israel and Germany for their support. The Israeli Ministry of Science (Grant # 2004-1-99) and CapCure Foundation supported in part this work.
- CCCD camera
- Gene therapy
- In vivo delivery
- In vivo imaging