Biomechanics of subcellular structures by non-invasive Brillouin microscopy

Abstract

Cellular biomechanics play a pivotal role in the pathophysiology of several diseases. Unfortunately, current methods to measure biomechanical properties are invasive and mostly limited to the surface of a cell. As a result, the mechanical behaviour of subcellular structures and organelles remains poorly characterised. Here, we show three-dimensional biomechanical images of single cells obtained with non-invasive, non-destructive Brillouin microscopy with an unprecedented spatial resolution. Our results quantify the longitudinal elastic modulus of subcellular structures. In particular, we found the nucleoli to be stiffer than both the nuclear envelope (p < 0.0001) and the surrounding cytoplasm (p < 0.0001). Moreover, we demonstrate the mechanical response of cells to Latrunculin-A, a drug that reduces cell stiffness by preventing cytoskeletal assembly. Our technique can therefore generate valuable insights into cellular biomechanics and its role in pathophysiology.

The role of cell body density in ruminant retina mechanics assessed by atomic force and Brillouin microscopy

“…The overall elastic stiffness of retinal tissue measured in this study was comparable to that of other CNS tissues assessed by AFM (6, 8–11, 47, 50–52). Similarly, the Brillouin shifts we measured in the retina are comparable with values published in previous literature (18, 20, 21). …”

“…We used two different ruminant species for our experiments, sheep and cows. The morphological structure of ovine and bovine retinae is very similar (21) (figure 1), suggesting that their mechanical properties are also likely similar.…”

Long-term Brillouin imaging of live cells with reduced absorption-mediated damage at 660nm wavelength

“…These specifications are met by gas lasers and solid-state lasers typically abundant in the blue/green region of the spectrum while semiconductor lasers, often used in the near-infrared region, usually present side modes and noise from amplified spontaneous emission. Indeed, Brillouin studies so far have used frequency doubled solid-state lasers, most using 532 nm wavelength of Nd:YAG laser, some using 561 nm [9,27,28] and one using 671 nm [29]. For in vivo studies, where photodamage is a strict concern, Brillouin studies have used near infrared wavelength (780 nm) employing semiconductor lasers and additional spectral purification elements [13,[30][31][32].…”

Imaging mechanical properties of sub-micron ECM in live zebrafish using Brillouin microscopy

“…Furthermore, it does not require artificial labelling nor external loading of the sample, thus making it a promising label-free and non-contact method to study mechanical properties of living tissues. In recent years, Brillouin microscopy has enabled applications in cell biology [12][13][14], ophthalmology [15,16], as well as disease detection [17]. Previous works have established that it is in principle feasible to measure cell mechanical properties with subcellular resolution [12,13].…”

“…In recent years, Brillouin microscopy has enabled applications in cell biology [12][13][14], ophthalmology [15,16], as well as disease detection [17]. Previous works have established that it is in principle feasible to measure cell mechanical properties with subcellular resolution [12,13]. Furthermore, Schlüssler et al have used Brillouin microscopy for the biomechanical assessment of regenerating tissues in living zebrafish [18] and Palombo et al have studied the contribution to the Brillouin shift of different ECMs from various rat fibrous connective tissue ex-vivo as well as their relative fiber alignment [19].…”