Non-contact elastography methods in mechanobiology: a point of view

Abstract

In recent decades, mechanobiology has emerged as a novel perspective in the context of basic biomedical research. It is now widely recognized that living cells respond not only to chemical stimuli (for example drugs), but they are also able to decipher mechanical cues, such as the rigidity of the underlying matrix or the presence of shear forces. Probing the viscoelastic properties of cells and their local microenvironment with sub-micrometer resolution is required to study this complex interplay and dig deeper into the mechanobiology of single cells. Current approaches to measure mechanical properties of adherent cells mainly rely on the exploitation of miniaturized indenters, to poke single cells while measuring the corresponding deformation. This method provides a neat implementation of the everyday approach to measure mechanical properties of a material, but it typically results in a very low throughput and invasive experimental protocol, poorly translatable towards three-dimensional living tissues and biological constructs. To overcome the main limitations of nanoindentation experiments, a radical paradigm change is foreseen, adopting next generation contact-less methods to measure mechanical properties of biological samples with sub-cell resolution. Here we briefly introduce the field of single cell mechanical characterization, and we concentrate on a promising high resolution optical elastography technique, Brillouin spectroscopy. This non-contact technique is rapidly emerging as a potential breakthrough innovation in biomechanics, but the application to single cells is still in its infancy.

The Role of Mechanotransduction in Contact Inhibition of Locomotion and Proliferation

“…Although it is likely that mechanical activation of FLNA occurs at high strain, the precise relationship between FLNA activation and the deformation of actin networks has not been thoroughly investigated. Various methods exist to measure the nanomechanics of individual proteins, as well as the viscoelastic properties of biopolymers, cells, and tissues, and to manipulate these properties for the study of CI and mechanotransduction [251][252][253][254][255]. Despite these advancements, there is still a need for further research to develop a comprehensive theory that can establish a connection between the measured mechanical properties and their impact on biological phenotypes.…”

Brillouin scattering from biomedical samples: the challenge of heterogeneity

“…This breakthrough has fuelled the growing demand for BLS hyperspectral viscoelastic imaging of biomedical samples. In fact, BLS imaging can accelerate research in areas such as biomechanics [14,15], mechanobiology [16,17], and tissue engineering [18,19] by providing access to valuable information about the biomechanical properties of cells and tissues [20][21][22]. It is evident that enhancing the reliability of spectral interpretation can significantly expand the clinical utility of BLS imaging, paving the way for innovative diagnostic tools and for evaluating tissue health and disease [22][23][24][25].…”

Brillouin spectroscopy for accurate assessment of morphological and mechanical characteristics in micro-structured samples

“…After its theoretical prediction by Leon Brillouin a century ago [1], Brillouin spectroscopy has become an important tool for investigating the mechanical properties of homogeneous materials. This technique is based on the interaction of light with the acoustic waves that spontaneously propagate inside the sample to extract information about their mechanical properties: the viscoelastic characterization occurs without any physical contact or labeling, unlike other commonly used approaches [2][3][4][5][6]. This peculiar characteristic made Brillouin spectroscopy a valuable technique to measure the mechanical properties of biological and biomedical samples [7][8][9][10][11][12].…”