Ruprecht Karls Universität Heidelberg


Cell and tissue mechanics

This seminar combines an introduction into the fundamentals of cell and tissue mechanics with a discussion of recent advances in this field. Contributing students are assigned reading material both from standard text books and/or from recent papers from research journals like Biophysical Journal or PNAS. The seminar takes place each Wednesday from 14.15 to 15.45 in seminar room 215 INF 293. The language is English in order to allow non-German speakers to participate.

Like all features of biological systems, also the mechanics of cells and tissues has evolved to fulfill very specific purposes. In strong contrast to most men-made constructions like houses or cars, however, they are based on soft rather than solid matter. Although this makes them vulnerable against mechanical impact, it endows biological structures with an ability to mechanically adapt to the environment in a way which is unsurpassed in synthetic materials. As an example for the mechanical requirements a cell is able to meet, imagine a white blood cells which after exit from the bone marrow fist travels the blood stream, thereby adapting to the shapes of the blood capillaries and withstanding the shear forces from the blood flow; exits from the blood stream by squeezing through the enclosing endothelium; migrates through the porous extracellular matrix of the surrounding tissue; in finally engulfs some pathogens by firmly wrapping itself around it.

The seminar offers an introduction to our current understanding of the mechanical principles at work with cells and tissues. The structural integrity of cells and tissues is essentially provided by the following elements:

  • the lipid bilayer, most importantly the plasma membrane
  • the cortex underlying the plasma membrane, like the spectrin network in red blood cells or the actin cortex in tissue cells
  • additional intracellular cytoskeletal elements, like stress fibers, microtubules, and the intermediate filaments
  • the extracellular matrix, a mixture of different types of molecules filling the space between cells
We will cover the physical concepts needed to describe these structural elements, including elasticity of thin shells, viscoelasticity and fiber networks. Possible subjects for presentations on recent advances include:
  • shape of red blood cells as determined by plasma membrane and spectrin network
  • mechanical properties of cells in suspension probed by the optical stretcher
  • AFM on cells
  • Rheology of gels and cells, including one- and two-bead-microrheology
  • fibers networks as models for the cytoskeleton and the extracellular matrix
  • force generation by polymerization
  • force generation by contractility
  • cell spreading and adhesion
  • overall design principles for cells and tissues (including tensegrity)
  • tissue growth

Recommended literature

  • Bruce Alberts et al., Molecular Biology of the Cell, 4th edition 2002, chapters 16 (cytoskeleton) and 19 (cell adhesion and extracellular matrix)
  • David Boal, Mechanics of the cell, Cambridge University Press 2002
  • Constantine Pozrikidis, editor, Modeling and Simulation of Capsules and Biological Cells, Chapman & Hall/CRC Press, 2003
  • Yuan-Cheng Fung, Biomechanics: mechanical properties of living tissues, 2nd edition, Springer 1993
  • Joe Howard, Mechanics of motor proteins and the cytoskeleton, Sinauer Associates 2001

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Last modified Fr Jul 28 08:43:28 CEST 2006

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