4.7. In Vivo and Ex Vivo Fluorescence Imaging

In vivo fluorescence imaging of the DID-labeled cells was performed with an IVIS Lumina II system (PerkinElmer, Waltham, MA, USA) using the 740/780 nm filter pair. All the mice were ventrally shaven from the cervical to the pubis region before imaging. The accumulation of the labeled cells in the tumor, lungs, liver and spleen was quantified using the total radiant efficiency (p/s/µW/cm²). Reported values were normalized to the background fluorescence of each individual mouse before injection of BMDMs. Since spleen mobility can cause spleen and liver to overlap in vivo, the fluorescence of these organs was combined into one region of interest (ROI). ROI dimensions were kept constant for all the mice.