Fluorescent Proteins as Visible In Vivo Sensors - Progress in Molecular Biology and Translational Science - page 389

Figure 10.1 Non-invasive image of GFP and RFP human tumors in the brain in a nude
mouse. GFP- and RFP-expressing U87 human glioma cells were implanted in the brain in
a single nude mouse. The excitation light was produced with a simple blue-LED flash-
light equipped with an excitation filter with a central peak of 470 nm. The image was
acquired with a Hamamatsu charge-coupled device (CCD) camera. 13

images are readily quantifiable; (iii) there is negligible interference from
autofluorescence; and (iv) very simple and low-cost instruments can be used
for GFP and RFP whole-body macroimaging, including LED (light-
emitting diode) flashlights with proper filters ( Fig. 10.1 ). 13
A novel, RFP-expressing pancreatic cancer model was orthotopically
established in nude mice. 17 The MIA-PaCa-2 human pancreatic cancer cell
line was transduced with RFP and grown subcutaneously. Fluorescent tumor
fragments were then surgically transplanted onto the nude mouse pancreas.
Groups treated with intraperitoneal gemcitabine or intravenous irinotecan
were sequentially imaged to compare, in real time, the anti-metastatic and
anti-tumor efficacy of these agents compared with untreated controls. The
anti-metastatic efficacy of each drug was followed noninvasively in real time
by imaging the RFP-expressing tumor and metastases and was confirmed by
fluorescence open imaging of autopsy specimens. This highlymetastaticmodel
reliably simulates the aggressive course of human pancreatic cancer. Noninva-
sive, sequential imaging permits quantification of tumor growth and dissemi-
nation and, thereby, real-time evaluationof therapeutic efficacy. These features
make this model an ideal pre-clinical system with which to study novel ther-
apeutics for pancreatic cancer.

2.1. Noninvasive cellular and subcellular imaging in vivo

Our laboratory has developed dual-color fluorescent cells with one color
in the nucleus and the other in the cytoplasm, which enable real-time
nuclear-cytoplasmic dynamics to be visualized in living cells in vivo as well