Sunday, December 26, 2021

Brain tumours spread by exploiting fundamental physics of viscoelasticity

Good news! Another step towards cancer is history!

"New research in Germany shows that changes to the mechanical properties of cells can cause a brain tumor to become malignant. [Researchers] have shown that a brain tumor is a unique material and its spread is driven by physics as well as biomechanics. Using research conducted on tumors in living patients, they suggest that small changes to the elasticity of cells produce collective effects that impact the prognosis of a tumor. ...
... pioneered the use of low frequency vibrations combined with magnetic resonance imaging (MRI) to measure the progression of diseases such as cancer. This technique is called magnetic resonance elastography (MRE). ... the inventors of the optical stretcher, which was also used in this study. An optical stretcher is an optical trap that uses two laser beams to deform single cells and measure their viscoelastic properties. ...
In 2019, the [researchers] discovered, using MRE, that glioblastoma, the deadliest form of brain cancer, is softer and less viscous than a benign brain tumour. Glioblastomas are almost impossible to remove because they grow by spreading tiny “fingers” into the surrounding tissue. The researchers realized that this growth could be driven by pure physics because “viscous fingers” are a well-known effect that arises when a low viscosity liquid is injected into another fluid. ...
it was the stretchiness and elasticity of the cells that was correlated with the fluidity of the tissue. For a tumor to “flow” into the surrounding tissue, the cells must squeeze past each other, and the researchers believe that this makes elasticity, rather than viscosity, the mediator of tissue fluidity. They also observed that the tumor cells had a much wider range of mechanical properties than would be expected in a healthy sample. This is consistent with what is known about cancer, which breaks down regulation processes in cells. ..."

From the abstract:
"... OS [optical stretcher] experiments measured cellular creep deformation in response to laser-induced step stresses. We used a Kelvin-Voigt model to deduce two parameters related to cellular stiffness (μKV) and cellular viscosity (ηKV) from OS measurements in a time regimen that overlaps with that of MRE. We found that single-cell μKV was correlated with |G*| (R = 0.962, p < 0.001) and G'' (R = 0.883, p = 0.004) but not G' of the bulk tissue. These results suggest that single-cell stiffness affects tissue viscosity in brain tumors.  ..."

Brain tumours spread by exploiting fundamental physics – Physics World




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