Spread of brain tumors explained using principles of fluid physics

Josef Käs from the University of Leipzig and Ingolf Sack from the Charité-Universitätsmedizin Berlin have shown that the spread of Brain tumor cells depends on both their physical and biomechanical properties. According to the researchers, a small change in the elasticity of glioma cells - the most dangerous brain tumor - significantly changes its ability to metastasize.

Sack is a chemist and Käs is a physicist. Both specialize in cancer research, but from different perspectives. Sack studies the mechanical properties of fabrics and has the technology of Magnetic resonance elastography developed a combination of low frequency vibrations and Magnetic resonance. It is used to track the progress of diseases. Käs, on the other hand, works with one optical trap, in which soft miniature objects such as cells can be deformed with the help of lasers to create their elasticity and to investigate deformability.

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Two years ago, the two scientists discovered that Glioma cells are softer and less sticky than cancer cells from non-malignant tumors. Since a glioma is difficult to remove because it extends small "tentacles" into the surrounding tissue, the scientists realized that the only laws of physics can control the spread of this cancer. The appearance of such "tentacles" is a well-known phenomenon in fluid physics when a fluid is less Viscosity is introduced into another liquid.

The researchers managed to recruit eight patients for the study, four of whom were benign Brain tumors and four with malignant tumors, including three with gliomas. The results of the study surprised the researchers themselves. What was remarkable was that the mechanical properties of a single cell were reflected in the mechanical properties of the entire tissue, says Käs. However, the data obtained suggest a more complex picture than just sticky cells forming a sticky tumor.

In previous studies, malignant tumors were softer and less viscous than benign tumors. However, and this was surprising, the cells they formed were no less viscous. It turned out that the most important thing was the stretchability and elasticity of the cells. This correlated with the ability of the tissue to "flow". In order to spread, they had to Tumor cells squeeze between other cells. According to the researchers, this is flexibility, not that Viscosity the most important factor in a tissue's ability to spread.

Cancer cells do not need to make any special genetic changes to begin the process of "extending their tentacles". All you need are the right mechanical properties. According to Käs, this is sufficient for highly invasive tissue growth.

The discovery by the German scientists is both bad and good news from a therapeutic point of view. The bad news is that mechanical properties are more difficult to perturb than molecular processes. The good news is that we now know the mechanism. When physical changes can make a tumor more malignant, they can also make it more benign. Understanding this process could help develop new therapies in the future.