Page "Luciferase" Paragraph 41

Whole animal imaging ( referred to as in vivo or, occasionally, ex vivo imaging ) is a powerful technique for studying cell populations in live animals, such as mice.

Different types of cells ( e. g. bone marrow stem cells, T-cells ) can be engineered to express a luciferase allowing their non-invasive visualization inside a live animal using a sensitive charge-couple device camera ( CCD camera ). This technique has been used to follow tumorigenesis and response of tumors to treatment in animal models.

However, environmental factors and therapeutic interferences may cause some discrepancies between tumor burden and bioluminescence intensity in relation to changes in proliferative activity.

The intensity of the signal measured by in vivo imaging may depend on various factors, such as D-luciferin absorption through the peritoneum, blood flow, cell membrane permeability, availability of co-factors, intracellular pH and transparency of overlying tissue, in addition to the amount of luciferase.