Menu

Close

Polyacrylamide Bead Sensors for in vivo Quantification of Cell-Scale Stress in Zebrafish Development

Nicole Traeber, Klemens Uhlmann, Salvatore Girardo, Gokul Kesavan, Katrin Wagner, Jens Friedrichs, Ruchi Goswami, Keliya Bai, Michael Brand, Carsten Werner, Daniel Balzani, Jochen Guck,

Preprint posted on September 18, 2018 https://doi.org/10.1101/420844

Article now published in Scientific Reports at http://dx.doi.org/10.1038/s41598-019-53425-6

Sensing cell-scale mechanical stress in vivo with polyacrylamide beads

Selected by Jacky G. Goetz

Summary

This preprint from the group of Jochen Guck provides an elegant method to accurately assess and quantify compressional forces in real-time in vivo.

The new methodolody is based on cell-like polyacrylamide (PAAm) beads sensors, which have defined size and elastic properties. Interestingly, the PAAm have been designed to mimic real cells:

– they display a uniform particle size of 17 µm;

– the elastic modulus was chemically adjusted to mimic the typical stiffness of eukaryotic cells (1,8 kPa);

– they have been rendered bioadhesive and fluorescent (thus trackable in vivo) by coating with Poly-L-Lysine conjugated with Cy3 fluorophores.

– they are compressible and volume changes can be used to assess bead elasticity and deformations at small compressions.

Such properties (size, compressibility, elastic modulus, biocompatibility and fluorescence) thus provide a new and elegant method for assessing bead deformations in vivo.

The study also provides a computational method for tracking bead-mediated stress sensing. This method, named COMPAX (for computational analysis-based cell-scale stress sensing) is composed of 3 steps :

  1. registration of deformed PAAm beads based on 2D confocal images
  2. comparison of the deformed configuration to the undeformed one (the undeformed bead being considered as a sphere with a mean diameter of 17 µm
  3. Finite Element simulation to obtain stress distribution over the deformed bead

After numerically validation the COMPAX method, the preprint further details that PAAm beads can sense mechanical stress in aggregates of mesenchymal stem cells in vitro. The authors then injected the PAAm beads in the developing neural plate of a zebrafish embryo. Doing so, they were capable of quantifying the deformations of embedded PLL-Cy3 PAAm beads by computational reconstruction. The method allows now to estimate the direction of main shape changes during neural rod formation in vivo in zebrafish embryos

Bigger picture

This work beautifully demonstrates that functionalized PAAm beads can be efficiently injected into living embryos to quantitatively assess mechanical stress in vivo. Numerical comparison of the bead deformation from the spherical shape of the reference configuration allows to quantitatively probe pressure changes as well as the direction of main shape changes.

Such work expands on preexisting methods for interrogating mechanical stress in vivo. While most of the techniques could only be applied to in vitro situations (such as atomic force microscopy or micropipette aspiration assay) or used FRET-based biosensor methods that are not compatible with cell-scale stress, recent work had demonstrated the power of biocompatible oil microdroplets or elastic round microgels. While oil microdroplets are incompressible, the accuracy of the second method strictly relies on measurements of stress-free microgels with spherical shape.

This new method described within this preprint will very likely provide a useful tool to probe spatiotemporal mechanical stress during developmental processes.

Open questions

This method is perfectly suited for tracking morphogenetic processes in developing embryos, but not only. Indeed, it would be interesting to test such PAAm beads in other physiological and pathological scenarios. In particular, one could probe mechanical stress during tumor growth and invasion using the PAAm beads.

From the experimental point of view, the next steps could aim at:

– testing bead deformations in other developing tissues

– testing bead deformations in other animal small organism models (and organoïds, as proposed by the authors)

– testing the compatibility of such method with intravital imaging (and computation) in mouse models

Tags: beads, biomechanics, development, pressure, stress, zebrafish

Posted on: 21st September 2018

doi: https://doi.org/10.1242/prelights.4869

Read preprint (2 votes)




  • Have your say

    Your email address will not be published. Required fields are marked *

    This site uses Akismet to reduce spam. Learn how your comment data is processed.

    Sign up to customise the site to your preferences and to receive alerts

    Register here

    Also in the developmental biology category:

    3D Gastruloids

    A curated list of preprints related to Gastruloids (in vitro models of early development obtained by 3D aggregation of embryonic cells)

     



    List by Paul Gerald L. Sanchez and Stefano Vianello

    ASCB EMBO Annual Meeting 2019

    A collection of preprints presented at the 2019 ASCB EMBO Meeting in Washington, DC (December 7-11)

     



    List by Madhuja Samaddar, Ramona Jühlen, Amanda Haage, Laura McCormick, Maiko Kitaoka

    EDBC Alicante 2019

    Preprints presented at the European Developmental Biology Congress (EDBC) in Alicante, October 23-26 2019.

     



    List by Sergio Menchero, Jesus Victorino, Teresa Rayon, Irepan Salvador-Martinez

    EMBL Seeing is Believing – Imaging the Molecular Processes of Life

    Preprints discussed at the 2019 edition of Seeing is Believing, at EMBL Heidelberg from the 9th-12th October 2019

     



    List by Gautam Dey

    SDB 78th Annual Meeting 2019

    A curation of the preprints presented at the SDB meeting in Boston, July 26-30 2019. The preList will be updated throughout the duration of the meeting.

     



    List by Alex Eve

    Lung Disease and Regeneration

    This preprint list compiles highlights from the field of lung biology.

     



    List by Rob Hynds

    Young Embryologist Network Conference 2019

    Preprints presented at the Young Embryologist Network 2019 conference, 13 May, The Francis Crick Institute, London

     



    List by Alex Eve

    Pattern formation during development

    The aim of this preList is to integrate results about the mechanisms that govern patterning during development, from genes implicated in the processes to theoritical models of pattern formation in nature.

     



    List by Alexa Sadier

    BSCB/BSDB Annual Meeting 2019

    Preprints presented at the BSCB/BSDB Annual Meeting 2019

     



    List by Gautam Dey

    Zebrafish immunology

    A compilation of cutting-edge research that uses the zebrafish as a model system to elucidate novel immunological mechanisms in health and disease.

     



    List by Shikha Nayar
    Close