(818d) Using Luciferase Expression to Quantify the Accumulation of Genetically Engineered Mesenchymal Stem Cells in Murine Tumors

Mesenchymal stem cells (MSCs) are bone marrow derived multipotent cells that can be expanded rapidly and genetically engineered to express therapeutic proteins. MSCs have a natural ability to home to tumors after systemic injection, but reduced homing capabilities arise after extended culture and genetic manipulation. Treatment strategies that increase the migration of genetically engineered cells are essential in the development of MSC-based gene delivery systems that home to tumors after infusion.

MSCs isolated from C57BL/6 mice were genetically engineered with a tetracycline inducible vector to express the luciferase reporter gene upon treatment with doxycycline. The inducibility of luciferase expression was characterized in vitro. Engineered MSCs and B16F1 tumor cells were co-implanted in C57BL/6 mice. Mice given control diet or doxycycline diet were imaged using the IVIS bioluminescent imaging system. Luciferase was easily visualized at the primary tumor site as well as in the lungs or tail of mice infused with genetically engineered MSCs. Luciferase expression will be used to track the location of systemically injected MSCs and to determine if in vitro treatment with soluble growth factors may be useful for improving the homing efficiency of genetically engineered MSCs.

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