This image shows an E2-Crimson expressing tumor cells (gray/white structures) in the organs of a rat after six weeks of tumor development. (Image: Working Group Shastri)
Diagnosing and treating tumours remains one of the grand challenges of medicine in the 21st century. For the translation of laboratory findings into human patients, animal models play a critical role. One way to visualize internal structures in living systems is to use light to selectively illuminate certain tissue, and analyse the reflected light to determine the structure. In such light-based imaging techniques, fluorophores - used as dyes - provide specificity and contrast, to distinguish one tissue from the other and to delineate specific tissue components.
The researchers from the University of Freiburg engineered breast cancer cells to express E2-Crimson - a protein that absorbs light in the far-red spectrum - and then grew these cells in a living system to form tumours. The scientists achieved the visualization of the tumour in real-time by illuminating the tumour expressing E2-Crimson with near infrared light followed by reconstruction of the tumour image using fluorescence molecular tomography. This enabled them to make two important findings: During the first four weeks of tumour development, the tumour volume increased not due to the increase in the tumour cells but due to the support matrix they were synthesizing. After four weeks, however, the tumour underwent a dramatic increase in the number of tumour cells. These new findings and the ability to provide visual and quantitative information on phases of tumour growth is important for selection of treatments and delivery of cancer drugs in the future.
Source: BIOSS - Centre for Biological Signalling Studies