Light scattering

Physics

Brillouin zone

Poromechanics

Laser

Porosity

Biology

Optics

Elasticity (physics)

Biophysics

Porous medium

Composite material

Viscoelasticity

Scattering

Materials science

Frequency dependence

Brillouin scattering

Nuclear magnetic resonance

Elastic modulus

Physical Review Letters

The structure of tumors can be recapitulated as an elastic frame formed by the connected cytoskeletons of the cells invaded by interstitial and intracellular fluids. The low-frequency mechanics of this poroelastic system, dictated by the elastic skeleton only, control tumor growth, penetration of therapeutic agents, and invasiveness. The high-frequency mechanical properties containing the additional contribution of the internal fluids have also been posited to participate in tumor progression and drug resistance, but they remain largely unexplored. Here we use Brillouin light scattering to produce label-free images of tumor microtissues based on the high-frequency viscoelastic modulus as a contrast mechanism. In this regime, we demonstrate that the modulus discriminates between tissues with altered tumorigenic properties. Our micrometric maps also reveal that the modulus is heterogeneously altered across the tissue by drug therapy, revealing a lag of efficacy in the core of the tumor. Exploiting high-frequency poromechanics should advance present theories based on viscoelasticity and lead to integrated descriptions of tumor response to drugs.

High-Frequency Mechanical Properties of Tumors Measured by Brillouin Light Scattering