Micromanipulation techniques presented in the modules:
- optical tweezers: Christoph Schmidt (2nd week)
- laser ablation/tissue mechanics: Thomas Lecuit, Matteo Rauzi (1st week)
- micropipette aspiration: Darius Koester (2nd week)
- Force apparatus using an optical fiber as cantilever: Pramod Pullarkat (1st week)
- micro-patterned surfaces: Matthieu Piel (2nd week)
- micro pillars: G.V. Shivashankar, Feroz Menon (1st week)
- stretchable surface: Bidisha Sinha (1st week)
- theory module: Madan Rao, Sriram Ramaswamy, Dave Odde, Dyche Mullins
- technical lectures: Carl-Philipp Heisenberg, Maria Garcia-Parajo, Benoit Ladoux
Each participants can join two modules per week, i.e. in total 4 modules. At the beginning of each week, the available modules will be introduced, and participants will then make their choice.
Some details about the abovementioned techniques:
Optical tweezers consist of a focused light beam which allows trapping micrometer sized objects such as polystyrene or glass beads. Optically trapped beads function as a handle to apply and/or to measure forces in the picoNewton range within or on cells 1.
Laser ablation is frequently used to study mechanical properties of tissues, e.g. developing Drosophila larvae. The impact of focused high energy laser pulses of a few micro-seconds duration is sufficient to disrupt connections between cells without disturbing neighboring parts of the tissue 2.
Micropipette aspiration is a versatile and easily to install tool that can be used to apply a controlled suction force to cells in order to measure the amount of excess membrane or to measure their elasticity3.
Optical fiber based force aparatus uses an optical fiber as a force sensor in combination with a piezo for applying deformations. This device is an improvement over the simpler glass needle technique employed previously for cell mechanics measurements. 4.
Shear stress/ cell rheology methods base in general on the application of a laminar flow of liquid on single or a monolayer of cells to study the cell’s reactions to this mechanical cue. More recently, several techniques have been developed to investigate rheology inside the cell 5,6.
Micro-patterned substrates confine the surface on which cells can adhere, and provide a mean to standardize cell shapes (of a large number of cells) allowing a quantitative study of cell morphology changes resulting from genetic or mechanical perturbations 7,8.
Stretchable surfaces like PDMS are a widely used tool to apply an axial stretch to the basal cell membrane. In addition, they can also serve to study the traction forces of cells by following substrate deformations 9,10
References
1. Veigel, C. & Schmidt, C. F. Moving into the cell: single-molecule studies of molecular motors in complex environments. Nature reviews. Molecular cell biology 12, 163–76 (2011).
2. Lecuit, T., Lenne, P.-F. & Munro, E. Force generation, transmission, and integration during cell and tissue morphogenesis. Annual review of cell and developmental biology 27, 157–84 (2011).
3. Hochmuth, R. M. Micropipette aspiration of living cells. Journal of Biomechanics133, 305–323 (2000).
4. Heidemann, S. R., Lamoureux, P. & Buxbaum, R. E. Cytomechanics of axonal development. Cell biochemistry and biophysics 27, 135–55 (1995).
5. Bernal, R., Melo, F. & Pullarkat, P. A. Drag force as a tool to test the active mechanical response of PC12 neurites. Biophysical journal 98, 515–23 (2010).
6. Hoffman, B. D. & Crocker, J. C. Cell mechanics: dissecting the physical responses of cells to force. Annual review of biomedical engineering 11, 259–88 (2009).
7. Théry, M., Jiménez-Dalmaroni, A., Racine, V., Bornens, M. & Jülicher, F. Experimental and theoretical study of mitotic spindle orientation. Nature 447, 493–6 (2007).
8. Duong, T., Goud, B. & Schauer, K. Closed-form density-based framework for automatic detection of cellular morphology changes. Proceedings of the National Academy of Sciences of the United States of America 109, 8382–7 (2012).
9. Saez, A. et al. Traction forces exerted by epithelial cell sheets. Journal of physics. Condensed matter?: an Institute of Physics journal 22, 194119 (2010).
10. Trepat, X. et al. Physical forces during collective cell migration. Nature Physics 5, 426–430 (2009).