Molecular Biology/Gene Expression
Molecular Biology/Gene Expression
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The ability to engineer mouse models that represent human disease is a valuable tool used by research groups around the world to better understand the biology of disease and drug targeting characteristics. A gap in sensitivity and resolution between in vivo and ex vivo techniques may make it hard to characterize an animal model. Using Cryo-Fluorescence Tomography (CFT), researchers can now obtain a 3D rendering of their mouse model to precisely understand the anatomical location of their genes of interest.

CFT – as high-res as it gets

Fluoro-tagged adeno-associated viruses (AAVs) are used to deliver genes to mammalian cells and express fluorescent marker proteins in animals. Cryo-fluorescence tomography (CFT) quantifies this fluorescence, and differentiates different AAV strains, across the whole animal.

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High-resolution localization of liver markers was achieved with CFT.

AAV liver markers

In this experiment, rats were treated with AAV9-GFP and observed 4 weeks later. Fluorescence was seen only in the liver. White light photography (left panel) showed the location to the liver. Using CFT, a fluorescent protein marker was detected (middle panel) and localized to the liver (right panel). Software analysis allowed the fluorescent marker to be quantified.
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Bioluminescence imaging (BLI) is commonly used in oncology studies but is limited because it can detect tumors only on a 2D scale.

CFT > BLI

CFT provides 3D images and can be co-visualized with white light imaging for anatomical landmarking. Thus, CFT provides a more accurate view of tumor location and size, even with very small tumors, in metastatic models/growing tumors than Bioluminescence imaging (BLI).
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BLI and CFT image of same tumor mouse model.
CFT image showing metastasis to the abdomen, lung, and bone not previously detected by bioluminescence

4T1 mouse mammary tumor cell line in immunodeficient mice.

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CFT, superior choice for metastasis studies

4T1 mice are used to study metastasis, where the tumor spreads from the breast to distant regions such as the lung, liver, lymph nodes, brain and bone. In this study, 4T1 mice expressing both luciferase and dsRed were visualized using both BLI and CFT. Using BLI (left panel) a few metastatic tumors were seen in the model. CFT (right panel) shows metastasis in the abdomen, lung, and bone not previously detected by BLI. CFT provided higher resolution and increased sensitivity imaging as compared to BLI in this study.

The Next Generation of Imaging. Xerra.