Abstract
BACKGROUND/AIM: In vivo imaging with luciferase-luciferin has been limited by the inability to visualize the low emitted light, with the signal quantified only by photon counting using a cumbersome highly-cooled CCD camera in a dark room. In the present study, we demonstrate direct visualization of the luciferase-luciferin signal from an orthotopic lung cancer in a nude-mouse xenograft model with a sensitive low-light camera and optics. MATERIALS AND METHODS: Mouse Lewis-lung carcinoma cells expressing luciferase (LL/2-Luc2) were injected transcutaneously into the lung of a nude mouse. One week later after cell injection, luciferase imaging for emission at 560 nm was performed using the UVP Biospectrum Advanced system after i.v. injection of D-luciferin potassium salt. The intensity of the visualized light was measured and quantified with the instrument. RESULTS: A week following the implantation of LL/2-Luc2 cells in nude mice, the luciferase-luciferin signal from LL/2-Luc2 tumors in the lung was sufficiently visible through the skin to produce true images. At fifteen minutes, the intensity peaked and then progressively dropped due to clearance of luciferin from the tumor. CONCLUSION: Using the UVP Biospectrum Advanced system we demonstrated non-invasive visualization of true images from luciferase-luciferin signals from an orthotopic lung-cancer mouse model. The luciferase-luciferin emitted light was directly visible through the skin which is a major improvement over previous photon counting to detect the luciferase-luciferin signal.