Abstract (eng)
Thy-1, also known as CD90, is a cell surface glycoprotein expressed in neurons, endothelial cells, thymocytes and many other cell types and plays a role in, among others, inhibition of neurite growth and melanoma cell migration. In mice, there are two alleles resulting in two sub-types, Thy-1.1 and Thy-1.2, whereas there is only one in humans. A transgenic mouse model was used for histological characterization in this thesis, were the reporter gene luciferase is expressed under the control of a Thy-1.2 promoter element. B16F10 melanoma cells with high metastatic potential and an aggressive growth pattern were implanted. Positive staining indi-cating CD90 expression was detected in tumors, brain and endothelial cells and lymphatic vessels in the skin. Furthermore, CD90 and the correlating expression of the transgene firefly luciferase under the control of the Thy-1.2-Luc expression cassette were detected in murine tissue of a breast cancer mouse model. As expected, this was not the case for implanted tu-mor cells. Since histological methods are limited in their resolution, 3D imaging offers a power-ful alternative. By combining fluorescence molecular tomography and computed tomography, in vivo real-time tracking of fluorescence emitting probes was achieved. To detect signals via fluorescence imaging tomography, fluorescence dyes like AF750 or quantum dots must be added to the formulations. To track biodistribution of naked siRNA, auropolyplexes loaded with siRNA, cadmium telluride quantum dots or polyethyleneimine-based quantoplexes, 3D images of living mice were taken at two different time-points after injection. Signals of each organ were marked by cuboid regions of interest and measured for further evaluation. To summarize, Thy-1 was efficiently detected in an implanted tumor of a Thy-1.2-Luc transgenic mouse model. Firefly luciferase was also successfully detected under control of the Thy-1.2-Luc ex-pression cassette in a breast cancer mouse model via immunohistochemistry. Furthermore, the biodistribution of siRNA and nanoparticles was efficiently tracked. SiRNA mainly accumu-lated in the kidneys and auropolyplexes were found in bladder and kidneys. Quantum dots showed a weak signal in the kidneys and quantoplex application resulted in signals in liver and lungs.