Noninvasive imaging of first generation adenovirus mediated systemic gene delivery in animal models

Molecular imaging is a technology that enhances our understanding of biological process in living organisms. Lately, noninvasive imaging of reporter gene expression in vivo became feasible by cooled charge-coupled device (CCD) camera. Tracing and quantifying the reporter gene expression in vivo is an important approach to monitor the expression of therapeutic genes in targeted tissues in disease models. Detection of the location, intensity, and time variation of reporter gene expression without need of invasive techniques is now possible.For this reason, in this study we wanted to apply a new light detection CCD camera for in vivo imaging of EGFP transgene expression in BALB/c mice. Various titers of first generation adenoviral vectors encoding enhanced green fluorescent protein (AdEGFP) was injected into BALB/c mice via tail-vein. After vector administration, AdEGFP mediated transgene expression was imaged at different time points by using a CCD camera.Our results showed that adenovirus delivered transgene expression was observed only in the liver after systemic vector administration. It peaked at day 4 and then remained detectable for at least 30 days by CCD camera. However, based on our results fluorescent signal detection in deep tissue could be enhanced 36% by surgical methods. These findings demonstrate that, noninvasive imaging provides functional data indicating the approximate location, magnitude, and duration of transgene expression for living organisms.