High-resolution line-scan Brillouin microscopy for live-imaging of mechanical properties during embryo development

Bevilacqua, Carlo; Gomez, Juan Manuel; Fiúza, Ulla-Maj; Chan, Chii Jou; Hambura, Sebastian; Eguren, Manuel; Ellenberg, Jan; Diz-Muñoz, Alba; Leptin, Maria; Prevedel, Robert

doi:10.1101/2022.04.25.489364

Cited by 15 publications

(18 citation statements)

References 45 publications

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“…While the spectral and thus overall image acquisition time of pulsed-SBS (~20 ms) is notably slower than recently developed line-scan Brillouin microscopy approaches [36][37][38] , we note that it is still faster than standard confocal implementations 8,12,39,40 , yet yields improved spectral linewidth fidelity and thus mechanical specificity, and in principle allows information to be obtained on the mass density. The limitations of pulsed-SBS are that it is presently restricted to relatively (i.e., non-absorbing) samples thinner than ~100-200 µm that can be optically accessed from two opposing sides.…”

Section: Discussionmentioning

confidence: 90%

Pulsed stimulated Brillouin microscopy enables high-sensitivity mechanical imaging of live and fragile biological specimens

Yang

Bevilacqua

Hambura

et al. 2022

Preprint

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Brillouin microscopy is an emerging optical elastography technique capable of assessing mechanical properties of biological samples in a 3D, all-optical and hence non-contact fashion. The typically weak Brillouin scattering signal can be substantially enhanced via a stimulated photon-phonon process, which improves the signal-to-background ratio (SBR) as well as provides higher spectral resolution. However, current implementations of stimulated Brillouin spectroscopy (SBS) require high pump powers, which prohibit applications in many areas of biology, especially when studying photosensitive samples, or when live-imaging in 3D and/or over extended time periods. Here, we present a pulsed SBS scheme that takes full advantage of the non-linearity of the pump-probe interaction in SBS. In particular, we show that through quasi-pulsing and diligent optimization of signal detection parameters, the required pump laser power can be decreased ~20-fold without affecting the signal levels or spectral precision. Moreover, we devise a custom analysis approach that facilitates the analysis of complex, multi-peaked Brillouin spectra in order to harness the high spectral resolution of SBS for the specific identification of biomechanical components inside the point-spread function of the microscope. We then demonstrate the low-phototoxicity and high-specificity of our pulsed SBS approach by imaging sensitive single cells, zebrafish larvae, and mouse embryos as well as adultC. eleganswith sub-cellular detail. Furthermore, our method permits observing the mechanics of organoids andC. elegansembryos over time. We expect that the substantially lower photo-burden and improved SBR of pulsed SBS will facilitate studying biomechanics in 3D at high spatio-temporal resolution in living biological specimens in a non-invasive manner, opening up exciting new possibilities for the field of mechanobiology.

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Section: Discussionmentioning

confidence: 90%

Pulsed stimulated Brillouin microscopy enables high-sensitivity mechanical imaging of live and fragile biological specimens

Yang

Bevilacqua

Hambura

et al. 2022

Preprint

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“…It relies on the interaction and inelastic scattering of monochromatic laser light from thermally driven acoustic phonons at high frequencies. The scattered light spectrum is indicative of the material's local mechanical properties, as shown by recent work on mouse ovaries and living embryos (Chan et al, 2021;Bevilacqua et al, 2022). Another imaging technique is second harmonic generation microscopy, which probes the tissue composition and the molecular structure of collagen with high sensitivity and specificity.…”

Section: Biomechanical Characterisation Of Ovarian Mechanicsmentioning

confidence: 99%

Squeezing the eggs to grow: The mechanobiology of mammalian folliculogenesis

Biswas

Prabhakaran

et al. 2022

Front. Cell Dev. Biol.

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The formation of functional eggs (oocyte) in ovarian follicles is arguably one of the most important events in early mammalian development since the oocytes provide the bulk genetic and cytoplasmic materials for successful reproduction. While past studies have identified many genes that are critical to normal ovarian development and function, recent studies have highlighted the role of mechanical force in shaping folliculogenesis. In this review, we discuss the underlying mechanobiological principles and the force-generating cellular structures and extracellular matrix that control the various stages of follicle development. We also highlight emerging techniques that allow for the quantification of mechanical interactions and follicular dynamics during development, and propose new directions for future studies in the field. We hope this review will provide a timely and useful framework for future understanding of mechano-signalling pathways in reproductive biology and diseases.

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“…We tackled the spatial aspect using confocal Brillouin microscopy 46,47 , a label-free optical technique that has been previously used to quantify the embryonic tissue mechanics of the spinal cord, cornea, and fly ventral furrow during gastrulation [48][49][50] . Brillouin microscopy measures the frequency shift (i.e., Brillouin shift) between incident and scattered light caused by the interaction of incoming photons with inherent (spontaneous) acoustic waves in biological materials 51 (Fig.…”

Section: Crowding Of Ureteric Bud Tip Domains Creates Crystal-like Pa...mentioning

confidence: 99%

“…We next sought to validate the spatial aspect of our hypothesis using confocal Brillouin microscopy 52,53 , a label-free optical technique that has been previously used to quantify the embryonic tissue mechanics of the spinal cord, cornea, and fly ventral furrow during gastrulation [54][55][56] . Brillouin microscopy measures the frequency shift (i.e.…”

Section: Crowding Of Ureteric Bud Tip Domains Creates Crystal-like Pa...mentioning

confidence: 99%

Tubule jamming in the developing mouse kidney creates cyclical mechanical stresses in nephron-forming niches

Viola

Liu

Prahl

et al. 2022

Preprint

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The kidney develops through elaboration of ureteric epithelial tubules (the future urinary collecting ducts), stroma, and nephron progenitors in the cap mesenchyme that surrounds each ureteric tip as they branch. Dynamic interactions between these tissues coordinate a balance between ureteric tip branching and nephron formation that sets nephron numbers for life, which impacts the probability of adult disease. How then is this balance achieved? Here we study the geometric and mechanical consequences of tubule tip crowding at the embryonic kidney surface and its effect on nephron formation. We find that kidney surface curvature reduces and tubule 'tip domains' pack more closely over developmental time. These together create a semi-crystalline geometry of tips at the kidney surface and a rigidity transition to more solid-like tissue properties at later developmental stages. New tips overcome mechanical resistance as they branch, expand, and displace close-packed neighbors, after which residual mechanical stress dissipates. This correlates with a changing nephrogenesis rate over the tip 'life-cycle'. To draw a causal link between the two, we mimic a mechanical transient in human iPSC-derived nephron progenitor organoids and find increased cell commitment to early nephron aggregates. The data suggest that temporal waves of mechanical stress within nephron progenitor populations could constitute a clock that synchronizes nephron formation and ureteric tubule duplication after E15. Ongoing efforts to understand the spatial and temporal regulation of nephron induction will clarify variation in nephron endowment between kidneys and advance engineered kidney tissues for regenerative medicine.

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High-resolution line-scan Brillouin microscopy for live-imaging of mechanical properties during embryo development

Cited by 15 publications

References 45 publications

Pulsed stimulated Brillouin microscopy enables high-sensitivity mechanical imaging of live and fragile biological specimens

Pulsed stimulated Brillouin microscopy enables high-sensitivity mechanical imaging of live and fragile biological specimens

Squeezing the eggs to grow: The mechanobiology of mammalian folliculogenesis

Tubule jamming in the developing mouse kidney creates cyclical mechanical stresses in nephron-forming niches

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