Menu

Close

Tissue size controls patterns of cell proliferation and migration in freely-expanding epithelia

Matthew A. Heinrich, Julienne M. LaChance, Tom J. Zajdel, Ricard Alert, Andrej Košmrlj, Daniel J. Cohen

Preprint posted on February 28, 2020 https://www.biorxiv.org/content/10.1101/2020.02.28.970418v1

Size matters - epithelial tissue size dictates proliferation and migration dynamics

Selected by Ilaria Di Meglio

BACKGROUND

Cell proliferation and migration control represents a critical aspect of tissue formation and maintenance in vivo. However, the exact mechanisms by which tissues coordinate cellular behaviour to give rise to the complexity of a living organism are not fully understood. Among the first descriptions of tissue size control was the concept of contact inhibition, a term first proposed over half a century ago [1], which refers to the inhibition of cell migration and eventually proliferation [2] due to extensive mutual contact between cells as density in a tissue increases. Since then, many in vitro studies have employed model epithelial tissues to elucidate the underlying mechanisms that drive migration and proliferation control [3-8]. However, as remarked by Heinrich et al, most studies have restricted tissue growth to the sub-millimetric scale (<500 microns) and have not assessed long-term growth (more than 24 hours), which may give rise to emergent complexity of the tissue. With this in mind, the authors investigate how tissue size affects the spreading and growth of a model MDCK epithelium grown on patterns of >1mm in diameter.

 

KEY FINDINGS

A model epithelial tissue of MDCK cells is grown on circular patterns of either small (1.7mm) or large (3.4mm) diameter with the same starting cell density, and allowed to freely expand for over 46h (Fig.1). A first characterization of tissue dynamics indicates a difference in growth and migration dynamics between small and large tissues; relative area increase is greater for small tissues compared to large tissues, whereas tissue density increases monotonically in large tissues but not in small tissues. This difference is attributed to the finding that in the early stages of expansion of small tissues, migration plays a stronger role than cell division in small tissues. By relating the dynamics of area expansion to kinematic measurements, the authors find that the average radial expansion of the tissue depends on the perimeter-to-area ratio of the pattern and not on tissue size, which could explain why smaller patterns exhibit faster area expansion compared to larger patterns.

Figure 1 – Expansion dynamics of small (left) and large (right) millimetric-size cell monolayers over 46h of growth (taken from Fig. 1 in Heinrich et al., 2020)

 

Next, the authors characterize the migratory behaviour and find that migration dynamics at the outer edge are independent of tissue size; speed is high and constant in both small and large tissues. In contrast, migratory dynamics within the bulk of the tissue are size-dependent. Towards the inner region of tissues, the speed profile diverges, and small tissues exhibit a motile interior region while large tissues exhibit an interior region that is almost completely non-motile past 28h of growth. As opposed to speed, the radial component of the velocity field is almost identical for small and large tissues, decreasing as distance from the tissue edge increases. Interestingly, the difference between radial velocity and speed observed for small tissues is due to the emergence of tissue-spanning, fast vortices in the centre small tissues (Fig.2). The formation of these vortices coincides temporally and spatially with a local cell density minimum occurring in small tissues. Using a minimal model that recapitulates the cell density evolution in small and large tissues, the observed transient decrease in density at the centre of small tissues is attributed to the combination of outward tissue flow and exponential growth of the tissue.

Figure 2 – Cell trajectories for small (left) and large (right) tissues illustrate vortex formation in expanding epithelia (taken from Fig. 3 in Heinrich et al., 2020)

 

Finally, the authors also analyze the spatiotemporal cell cycle dynamics in small and large tissues by using MDCK cells expressing FUCCI, meaning that cells fluoresce in red (shown as magenta) during G1-phase and in green when in the S-G2-M phase of the cell cycle. Similar to migration dynamics, cell cycle dynamics are independent of tissue size in the outer region of tissues, where cells are in the S-G2-M phases and thus are actively cycling. In contrast, the inner regions of small and large tissues exhibit different dynamics; large tissues are populated primarily by (contact-inhibited) G1-phase cells, while small tissues exhibit a mix of both G1 and S-G2-M phase cells where local density minimum and vortices occur. The contact-inhibited state observed in the centre of large tissues actually propagates inwards and does not originate from the core of the tissue (Fig. 3).

Figure 3 – Fluorescence images at the end of the experiment (46h) of G1 phase (magenta) and G2 phase (green) cells shows spatial cell-cycle dynamics in small (left) and large (right) tissues (taken from Fig.5 in Heinrich et al., 2020)

 

Altogether, the authors show that tissue size dictates the migratory and proliferative behaviour of the tissue. Importantly, edge dynamics are conserved across tissue size whereas dynamics at the bulk of the tissue are not. In fact, while a small tissue eventually reaches the size of a large tissue, its internal dynamics are different from the large tissue at this size. Therefore, initial tissue size alters the growth constraints under which the tissue grows and this ultimately determines the growth patterns within the bulk of the tissue.

 

Why I like this preprint:

I found this preprint particularly interesting because it focuses on assessing the effect of tissue size and growth on the dynamics of both migration and proliferation. With a few exceptions, most studies using cultured MDCK cells focus on one of the two processes, yet the control and dynamics of both are equally important in the context of a growing tissue. Even more so, migration and proliferation patterns are highly interlinked, highlighting the importance of assessing both in a growing tissue. I think this study is also particularly relevant because it explores tissue dynamics at the larger scale, and indeed in vivo tissues can extend for millimeters or even meters! Finally, I liked the use of the FUCCI system in this study because it allows one to assess the effect of mechanics and in this case of tissue size on local cell cycle progression and not only on overall proliferation rate.

 

Questions to the authors:

  • The authors use plastic culture dishes in this study, which are several orders of magnitude stiffer than tissues. I think it would be interesting to assess the same dynamics at the millimetric-scale as has been done here but on substrates that are of physiologically relevant stiffness, which may give rise to further complexity in the dynamics observed.
  • Do you observe cell extrusion and if so is there a difference between small and large tissues, and between edge and tissue core?
  • The effect of aspect ratio on tissue expansion, which you assess by growing elliptical shaped tissues of major to minor axis ratios 8:1 or 4:1, also appears to impact vortex formation. The formation of a vortex is very evident in the movie S3 for the 8:1 tissue but not the 4:1 tissue – what could be the explanation for this difference?

References

  1. Abercrombie, M. and J.E. Heaysman, Observations on the social behaviour of cells in tissue culture. II. Monolayering of fibroblasts. Exp Cell Res, 1954. 6(2): p. 293-306.
  2. Stoker, M.G. and H. Rubin, Density dependent inhibition of cell growth in culture. Nature, 1967. 215(5097): p. 171-2.
  3. Nelson, C.M., et al., Emergent patterns of growth controlled by multicellular form and mechanics. Proc Natl Acad Sci U S A, 2005. 102(33): p. 11594-9.
  4. Puliafito, A., et al., Collective and single cell behavior in epithelial contact inhibition. Proc Natl Acad Sci U S A, 2012. 109(3): p. 739-44.
  5. Streichan, S.J., et al., Spatial constraints control cell proliferation in tissues. Proc Natl Acad Sci U S A, 2014. 111(15): p. 5586-91.
  6. Uroz, M., et al., Regulation of cell cycle progression by cell-cell and cell-matrix forces. Nat Cell Biol, 2018. 20(6): p. 646-654.
  7. Vedula, S.R., et al., Emerging modes of collective cell migration induced by geometrical constraints. Proc Natl Acad Sci U S A, 2012. 109(32): p. 12974-9.
  8. Wyatt, T.P., et al., Emergence of homeostatic epithelial packing and stress dissipation through divisions oriented along the long cell axis. Proc Natl Acad Sci U S A, 2015. 112(18): p. 5726-31

 

Posted on: 21st May 2020

doi: https://doi.org/10.1242/prelights.20855

Read preprint (No Ratings Yet)




  • 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 cell biology category:

    BioMalPar XVI: Biology and Pathology of the Malaria Parasite

    [under construction] Preprints presented at the (fully virtual) EMBL BioMalPar XVI, 17-18 May 2020 #emblmalaria

     



    List by Gautam Dey, Samantha Seah

    1

    Cell Polarity

    Recent research from the field of cell polarity is summarized in this list of preprints. It comprises of studies focusing on various forms of cell polarity ranging from epithelial polarity, planar cell polarity to front-to-rear polarity.

     



    List by Yamini Ravichandran

    TAGC 2020

    Preprints recently presented at the virtual Allied Genetics Conference, April 22-26, 2020. #TAGC20

     



    List by Maiko Kitaoka, Madhuja Samaddar, Miguel V. Almeida, Sejal Davla, Jennifer Ann Black, Gautam Dey

    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

    ECFG15 – Fungal biology

    Preprints presented at 15th European Conference on Fungal Genetics 17-20 February 2020 Rome

     



    List by Hiral Shah

    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

    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

    Autophagy

    Preprints on autophagy and lysosomal degradation and its role in neurodegeneration and disease. Includes molecular mechanisms, upstream signalling and regulation as well as studies on pharmaceutical interventions to upregulate the process.

     



    List by Sandra Malmgren Hill

    Lung Disease and Regeneration

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

     



    List by Rob Hynds

    Cellular metabolism

    A curated list of preprints related to cellular metabolism at Biorxiv by Pablo Ranea Robles from the Prelights community. Special interest on lipid metabolism, peroxisomes and mitochondria.

     



    List by Pablo Ranea Robles

    BSCB/BSDB Annual Meeting 2019

    Preprints presented at the BSCB/BSDB Annual Meeting 2019

     



    List by Gautam Dey

    MitoList

    This list of preprints is focused on work expanding our knowledge on mitochondria in any organism, tissue or cell type, from the normal biology to the pathology.

     



    List by Sandra Franco Iborra

    ASCB/EMBO Annual Meeting 2018

    This list relates to preprints that were discussed at the recent ASCB conference.

     



    List by Gautam Dey, Amanda Haage

    Also in the developmental biology category:

    Cell Polarity

    Recent research from the field of cell polarity is summarized in this list of preprints. It comprises of studies focusing on various forms of cell polarity ranging from epithelial polarity, planar cell polarity to front-to-rear polarity.

     



    List by Yamini Ravichandran

    TAGC 2020

    Preprints recently presented at the virtual Allied Genetics Conference, April 22-26, 2020. #TAGC20

     



    List by Maiko Kitaoka, Madhuja Samaddar, Miguel V. Almeida, Sejal Davla, Jennifer Ann Black, Gautam Dey

    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