Research
Mechano-genetic interactions in stem cell aggregates
Most animals display one or more body axes, such as the head-to-tail axis, which usually form during early embryogenesis. Such axis formation can be studied in vitro, in stem cell aggregates called gastruloids. While initially isotropic, gastruloids break rotational symmetry over the course of roughly a day, reflected in an asymmetric distribution of cell fates.
We want to understand how cell fate dynamics interacts with cell motion and tissue dynamics.
On this project, we work together with the experimental groups of Pierre-François Lenne (Marseille), Vikas Trivedi, and Verena Ruprecht (both Barcelona).
Recent publications:
Marangoni-like tissue flows enhance symmetry breaking of embryonic organoids, Simon Gsell*, Sham Tlili*, Matthias Merkel, Pierre-François Lenne. bioRxiv (2023).
Phase separation dynamics in deformable droplets. Simon Gsell, Matthias Merkel. Soft Matter 18(13), p. 2672-2683 (2022).
Dynamics of anisotropic tissues
A key process during animal development is the anisotropic deformation of tissues. Often, such deformation is actively driven and some kind of orientational information is inherently defined within tissues (for instance in terms of cell polarity or cell shape anisotropy). Yet, generic theories for such active materials with orientational information predict inherent instabilities. How could such instabilities be prevented to during animal development? To address this question, we study the interplay between orientational information and tissue mechanics using both cell-based and hydrodynamic models for biological tissues.
Recent publications:
Deforming polar active matter in a scalar field gradient. Muhamet Ibrahimi, Matthias Merkel. NJP 25(1), p. 013022 (2023).
Structure and Rheology in Vertex Models under Cell-Shape-Dependent Active Stresses. Shao-Zhen Lin, Matthias Merkel, Jean-François Rupprecht. PRL 130(5), p. 058202 (2023), arXiv.
Implementation of cellular bulk stresses in vertex models of biological tissues. Shao-Zhen Lin, Matthias Merkel, Jean-Francois Rupprecht. EPJE 45(1), p. 4 (2022).
Dynamics of curved tissues
Sheet-like biological tissues, called epithelia, are often curved during animal development. How does curvature affect the tissue dynamics? For instance, when tissues change their Gaussian curvature, then they need to deform tangentially. What are the consequences of this for tissue flow?
On this project, we work together with the group of Thomas Lecuit (Marseille).
Recent publications:
Curvature gradient drives polarized tissue flow in the Drosophila embryo. Emily Gehrels*, Bandan Chakrabortty*, Marc-Eric Perrin, Matthias Merkel, Thomas Lecuit. PNAS 120(6), p. e2214205120 (2023), bioRxiv.
Mechanics of under-constrained materials
How do large-scale properties of disordered systems arise from the complex interplay of their microscopic constituents? This question is important to understand a large class of materials both living and non-living. We have recently analytically show that the elastic properties of the broad class of under-constrained materials follows very generic relations. This is relevant to understand systems as diverse as semiflexible polymer networks like collagen, cell-based vertex models for biological tissue, and membranes.
Recent publications:
Connecting anomalous elasticity and sub-Arrhenius structural dynamics in a cell-based model. Chengling Li, Matthias Merkel, Daniel M. Sussman. arXiv (2024).
Generic elasticity of thermal, under-constrained systems. Cheng-Tai Lee, Matthias Merkel. arXiv (2023).
Partition sum of thermal, under-constrained systems. Cheng-Tai Lee, Matthias Merkel. arXiv (2023).
Stiffening of under-constrained spring networks under isotropic strain. Cheng-Tai Lee, Matthias Merkel. Soft Matter 18(29), p. 5410-5425 (2022).