A novel experimental platform for investigating the mechanics of cell monolayers
Lead Research Organisation:
University of Cambridge
Department Name: Engineering
Abstract
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Technical Summary
Exposure to mechanical stresses is a normal part of physiology for monolayers and their mechanical function is particularly apparent in disease when mutations or pathogens affecting the cytoskeleton, adherens junctions, or desmosomes result in increased fragility of tissues. Despite clear physiological relevance, little is known about the mechanics of monolayers and how these relate to the mechanical properties of the individual cells constituting the tissue. The challenge is to design an instrument that enables precise control over the mechanical environment of tissues on time scales from 0.1s to hours while allowing for simultaneous high resolution imaging of subcellular structures.
We propose to develop a versatile new experimental tool for measuring the mechanical properties of cell monolayers and applying well-characterised steady forces onto cell monolayers to study their responses to mechanical stresses at all the relevant time- and length-scales.
The tool will require precise control of the deformation and monitoring of the applied tension, with a compact design suitable for live microscopy imaging and environmental control. This will be achieved by using a closed-loop piezo drive to control deformation and a force sensor with an accuracy of 10uN to monitor tension. Control software will allow testing of time-dependent properties by imposing constant stress conditions or cycles of deformation. A laser ablation system will be built to create controlled cuts in the stretched tissue to characterise their resistance to fracture and measure their macroscopic adhesion energy. Image acquisition and image analysis will characterise cellular dynamics within the monolayer. High magnification microscopy combined with GFP-tagging will provide data regarding the subcellular organisation of the material. This new tool will pave the way for interdisciplinary investigations of monolayer mechanics and mechanotransduction at the molelular, cellular, and tissue levels.
We propose to develop a versatile new experimental tool for measuring the mechanical properties of cell monolayers and applying well-characterised steady forces onto cell monolayers to study their responses to mechanical stresses at all the relevant time- and length-scales.
The tool will require precise control of the deformation and monitoring of the applied tension, with a compact design suitable for live microscopy imaging and environmental control. This will be achieved by using a closed-loop piezo drive to control deformation and a force sensor with an accuracy of 10uN to monitor tension. Control software will allow testing of time-dependent properties by imposing constant stress conditions or cycles of deformation. A laser ablation system will be built to create controlled cuts in the stretched tissue to characterise their resistance to fracture and measure their macroscopic adhesion energy. Image acquisition and image analysis will characterise cellular dynamics within the monolayer. High magnification microscopy combined with GFP-tagging will provide data regarding the subcellular organisation of the material. This new tool will pave the way for interdisciplinary investigations of monolayer mechanics and mechanotransduction at the molelular, cellular, and tissue levels.
Planned Impact
Academic impact
Academic advancement and innovation:
To ensure the novel instrument has the highest possible research impact, we will present our technological developments and preliminary results generated at high profile conferences that cover relevant topics including tissue engineering, biophysics, developmental biology and cell biology in 2013 and 2014. We expect the instrument to attract interest from many fields in the global scientific community and that this will lead to the development of new international research collaborations over the next couple of years. Where possible we will disseminate our findings in general audience and/or open access journals. Furthermore, we expect that the imminent publication of our preliminary results in PNAS will bring attention of a wide audience onto the new instrument.
Training and professional development:
Both GC and AK are actively involved in interdisciplinary training activities at UCL and Cambridge University. GC runs the "quantitative biology" module for the UCL Systems Biology training program, participates in teaching in the CoMPLEX DTP, and is a member of the new interdisciplinary BBSRC DTP. AK is an important contributor to the development of the Bioengineering curriculum in Cambridge, and teaches a number of relevant subjects ranging from material sciences to physiology. The project described here will be used to introduce students from different backgrounds to interdisciplinary research in the life sciences. Elements of the work will be used as exemplar projects for students in the CoMPLEX and BBSRC DTPs. The mechanical aspects of the project will also form the basis of a couple of 4th year engineering projects in Cambridge and are likely to attract students with a Mechanical/Bio Engineering background.
Throughout the course of the project, the post-doc involved, already largely independent and technically capable to develop this project, will receive further cross-disciplinary mentoring and benefit from regular interactions both in Cambridge and London. In addition, he will be involved in mentoring students and develop his own mentoring and leadership skills. This will aid his progression towards an independent group leader position.
Societal and economic impact
Commercialisation and exploitation:
We expect our instrument to evolve towards a generic characterisation method within a couple of years and we will strive to use standardized components to enable interested laboratories to rapidly and easily build their own instrument using off-the-shelf components. We envisage that it could be utilized to study the effect of pathologic genetic mutations on tissue mechanical properties and test how drug treatments affect macroscopic tissue properties. Should there be interest from the pharmaceutical community, we will study the possibility of designing a new prototype in a format suited to high throughput screening.
Both the UCL and Cambridge University have efficient mechanisms to assist academics in the development of commercial applications of their research outputs and in the management of intellectual property rights (see for instance Cambridge Enterprise or UCL Business).
Increasing public engagement and understanding:
Previously members of the team have been involved in interactions with the wider community through public discussions and school visits. Through this type of outreach we expect this work to reach a wide audience, giving the public a better understanding of multidisciplinary research and an appreciation of the remarkable natural world in which we live. We expect to participate in one public engagement event during the course of this short project. We will use these opportunities to stress the important role played by basic science and engineering research in driving societal advances.
Academic advancement and innovation:
To ensure the novel instrument has the highest possible research impact, we will present our technological developments and preliminary results generated at high profile conferences that cover relevant topics including tissue engineering, biophysics, developmental biology and cell biology in 2013 and 2014. We expect the instrument to attract interest from many fields in the global scientific community and that this will lead to the development of new international research collaborations over the next couple of years. Where possible we will disseminate our findings in general audience and/or open access journals. Furthermore, we expect that the imminent publication of our preliminary results in PNAS will bring attention of a wide audience onto the new instrument.
Training and professional development:
Both GC and AK are actively involved in interdisciplinary training activities at UCL and Cambridge University. GC runs the "quantitative biology" module for the UCL Systems Biology training program, participates in teaching in the CoMPLEX DTP, and is a member of the new interdisciplinary BBSRC DTP. AK is an important contributor to the development of the Bioengineering curriculum in Cambridge, and teaches a number of relevant subjects ranging from material sciences to physiology. The project described here will be used to introduce students from different backgrounds to interdisciplinary research in the life sciences. Elements of the work will be used as exemplar projects for students in the CoMPLEX and BBSRC DTPs. The mechanical aspects of the project will also form the basis of a couple of 4th year engineering projects in Cambridge and are likely to attract students with a Mechanical/Bio Engineering background.
Throughout the course of the project, the post-doc involved, already largely independent and technically capable to develop this project, will receive further cross-disciplinary mentoring and benefit from regular interactions both in Cambridge and London. In addition, he will be involved in mentoring students and develop his own mentoring and leadership skills. This will aid his progression towards an independent group leader position.
Societal and economic impact
Commercialisation and exploitation:
We expect our instrument to evolve towards a generic characterisation method within a couple of years and we will strive to use standardized components to enable interested laboratories to rapidly and easily build their own instrument using off-the-shelf components. We envisage that it could be utilized to study the effect of pathologic genetic mutations on tissue mechanical properties and test how drug treatments affect macroscopic tissue properties. Should there be interest from the pharmaceutical community, we will study the possibility of designing a new prototype in a format suited to high throughput screening.
Both the UCL and Cambridge University have efficient mechanisms to assist academics in the development of commercial applications of their research outputs and in the management of intellectual property rights (see for instance Cambridge Enterprise or UCL Business).
Increasing public engagement and understanding:
Previously members of the team have been involved in interactions with the wider community through public discussions and school visits. Through this type of outreach we expect this work to reach a wide audience, giving the public a better understanding of multidisciplinary research and an appreciation of the remarkable natural world in which we live. We expect to participate in one public engagement event during the course of this short project. We will use these opportunities to stress the important role played by basic science and engineering research in driving societal advances.
People |
ORCID iD |
Alexandre Kabla (Principal Investigator) |
Publications
Bonfanti A
(2020)
A unified rheological model for cells and cellularised materials.
Bonfanti A
(2020)
A unified rheological model for cells and cellularised materials.
in Royal Society open science
Harris AR
(2013)
Generating suspended cell monolayers for mechanobiological studies.
in Nature protocols
Harris AR
(2014)
Formation of adherens junctions leads to the emergence of a tissue-level tension in epithelial monolayers.
in Journal of cell science
Khalilgharibi N
(2019)
Stress relaxation in epithelial monolayers is controlled by the actomyosin cortex.
in Nature physics
Wyatt T
(2019)
Actomyosin controls planarity and folding of epithelia in response to compression
in Nature Materials
Wyatt TP
(2015)
Emergence of homeostatic epithelial packing and stress dissipation through divisions oriented along the long cell axis.
in Proceedings of the National Academy of Sciences of the United States of America
Description | The goal of this BBSRC tools and resources grant was to develop a versatile new experimental tool for measuring the mechanical properties of cell monolayers and applying well-characterised steady forces onto cell monolayers to study their responses to mechanical stresses at all the relevant scales. The instrument was designed to work on millimeter size suspended epithelia. Our objectives were to design an instrument that could: (a) stretch epithelia on time-scales ranging from the fraction of a second to tens of hours. (b) accurately record stress on the tissue in the 10-105Pa range with an acquisition rate >10Hz. (c) image the evolution of cellular and subcellular morphology within the tissue during stretching. (d) study tissue fracture with a high degree of control. Objective a was achieved by integrating a fast and precise motorised micromanipulator into the experimental setup. This micromanipulator is piloted via Labview such that movement and feedback routines can be implemented to suit the experiments to be conducted. With this setup, strain rates >75%/s can be achieved signifying that a monolayer can be extended by 30% length in less than 0.5s. Driving at such fast rates allows the study of the rheology of monolayers. For long duration experiments designed to examine cellular responses to application of extrinsic mechanical stresses, the micromanipulator is utilised to apply the initial extension with high precision. The micromanipulator prong is then fixed at the final position using glue and detached from the micromanipulator arm. This allows multiple experiments to be carried out in parallel. Objective b was achieved by integrating an SI-KG7B force transducer into the setup. This allows measurement of forces up to 10mN with a 1µN precision at rates of >1kHz, far exceeding our original goals. Data acquisition is integrated into Labview, allowing force feedback routines to be implemented. Objective c was achieved by purchasing a long working distance high NA 30x objective and integrating the experimental platform into an environmentally controlled chamber. The new objective allows imaging of large fields of view with high signal and allows zooming on scanning laser confocals. Objective d required the integration of a laser ablation system to the setup to create controlled multi-cellular cracks in the tissue. The laser ablation system was built to interface directly to the FV-1000 laser lines and controlled through Olympus software (similar to the one described in 11). It allows the generation of subcellular cracks by cutting single junctions as well as multicellular cracks ranging from 1 to 10 cells in length. The fracture can be detected by optical microscopy using the objective and chamber described in objective c. Combined with molecular perturbations, these measurements will be applied to understanding the magnitude and biological origin of intercellular adhesion. |
Exploitation Route | The tool developed for this grant is now currently enabling research on: a) the biological origin of the elastic and viscous properties of monolayers b) the intercellular adhesion energy in monolayers c) the role of oriented mitoses and cell rearrangement in dissipating applied stresses (with Prof Buzz Baum, LMCB, UCL) d) the mechanical properties of Drosophila wing disk (With Dr Yanlan Mao, LMCB, UCL). |
Sectors | Pharmaceuticals and Medical Biotechnology |
URL | http://www.nature.com/nprot/journal/v8/n12/full/nprot.2013.151.html |
Description | We are not aware of others using the method at this stage. The work has however been published in Nature protocols and other laboratories, in and outside of academia, are now free to reproduce the setup. It is therefore likely that the tool will be picked up in future, if it has not been done already. |
Sector | Healthcare,Pharmaceuticals and Medical Biotechnology |
Description | The mechanics of epithelial tissues |
Amount | £689,610 (GBP) |
Funding ID | BB/M003280/1 |
Organisation | Biotechnology and Biological Sciences Research Council (BBSRC) |
Sector | Public |
Country | United Kingdom |
Start | 11/2014 |
End | 11/2017 |
Description | Collaboration with Buzz Baum |
Organisation | University College London |
Department | MRC Laboratory for Molecular Cell Biology |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | I formally cosupervise a PhD student from this institution. My lab is contributing ideas and theoretical tools. |
Collaborator Contribution | My partners are leading the experimental work and providing data. |
Impact | doi: 10.1098/rsfs.2014.0013 doi:10.1038/nprot.2013.151 doi: 10.1073/pnas.1213301109 |
Start Year | 2012 |
Description | Mechanisms of oriented cell division in stretched monolayers |
Organisation | University College London |
Department | MRC Laboratory for Molecular Cell Biology |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | This research utilises our experimental system to examine how tissue stretch orients cell division along the the axis of tension. |
Start Year | 2013 |
Title | Rheos |
Description | The software library provides a computational framework to model the rheological response of materials presenting a power law behaviour. Such behaviour has been observed across a broad range of biological materials. |
Type Of Technology | Software |
Year Produced | 2018 |
Open Source License? | Yes |
Impact | It has provided us with a reliable mechanism to extract material parameters in monolayers and embryo tissues. This has allowed the prediction of complex behaviours in monolayers, as recently reported in https://www.biorxiv.org/content/10.1101/543330v1. |
URL | https://github.com/JuliaRheology/RHEOS.jl |
Description | Cell Mechanics Workshop, Curie Institute - Invited contribution |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Postgraduate students |
Results and Impact | The goal of this workshop was to bring together biologists and experimental and theoretical physicists to discuss current topics in cell motility from different perspectives. A strong focus is made on the interaction during the talks and in between sessions. We aim at a mixed audience with a diverse scientific background and different levels of professional experience from students to leading scientists in the field. |
Year(s) Of Engagement Activity | 2015 |
URL | http://www.labex-celtisphybio.fr/cell-motility-workshop-2015/ |