Figure 3.

In vivo and ex vivo uptake of MC1RL-800 into tumor. A) Representative time-domain based fluorescence tomography image of MC1RL-800 accumulation in mouse xenograft tumors 2 hours after intravenous injection of 5 nmol/kg probe. A375 cells that constitutively express low levels of MC1R were used to form the low-expressing tumor (left flank) and A375/MC1R cells were used to form the high expressing tumor (right flank). Only the tumor areas were scanned. B) Top: In vivo tomographic slices (0.5 mm thickness) through the high-expression tumor from top to bottom (ordered from left to right). Below: Ex vivo surface radiance image of a center section from the high-expressing tumor (left) compared to the center slice from the in vivo tomographic image of the same tumor. An effort was made to maintain registration of the ex vivo section with the in vivo image slice. All analyses were performed using the Optix-MX3 Optiview Software (version 3.01). C) Ex vivo images of center sections from low- and high-expressing tumors with corresponding IHC staining of MC1R. D) Biodistribution of MC1RL-800 probe determined by quantification of ex vivo fluorescence values from the tumor, kidneys and liver at different time-points post-injection of 3 nmol/kg probe. No signal was detected in the heart, lung, brain and other organs (not shown). The values were normalized as percentage of the highest signal.