We thank the lab of Ulrich Schwarz for computational tracking software used in quantification of cellular traction forces (Sabass et al., 2008). This work was supported by a Burroughs Wellcome Career Award and NIH Director's Pioneer Award (DP10D00354) to M.L. Gardel and Medical Scientist National Research Service Award (5 T32 GM07281) to S.P. Winter.

1.	Activating the coverslip surface
<ol>
<li>	Coverslips (#1.5, 22x40 mm) are cleaned using a series of soap and ethanol washes in a previously described protocol (Waterman-Storer, 1998) to clean and remove dust.</li>
<li>	Place coverslips in a stainless steel holder rack, such that coverslips are spaced apart and not touching.</li>
<li>	In chemical fume hood (nitrile gloves and goggles recommended), dilute full strength 3-aminopropyltrimethoxysilane in isopropanol for a final concentration of 2% (2ml silane /100 m...

<ol>
	<li>Damljanovic, V., Lajerholm, B. C., Jacobson, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bulk+and+micropatterned+conjugation+of+extracellular+matrix+proteins+to+characterized+polyacrylamid+substrates+for+cell+mechanotransduction+assays.">Bulk and micropatterned conjugation of extracellular matrix proteins to characterized polyacrylamid substrates for cell mechanotransduction assays.</a> Biotechniques. 39 (6), 847-851 (2005).</li><li>Engler, A., Bacakova, L. N. e. w. m. a. n., Hategan, C., Griffin, A., M, D. D. i. s. c. h. e. r. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Substrate+compliance+versus+ligand+in+cell+on+gel+responses.">Substrate compliance versus ligand in cell on gel responses.</a> Biophys J. 86 ((1 Pt 1)), 617-628 (2004).</li><li>Gardel, M. L., Sabass, B., Ji, L., Danuser, G., Schwarz, U. S., Waterman, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Traction+stress+in+focal+adhesions+correlates+biphasically+with+actin+retrograde+flow+speed.">Traction stress in focal adhesions correlates biphasically with actin retrograde flow speed.</a> J Cell Biol. 183, 999-1005 (2008).</li><li>Rajagopalan, P., Marganski, W. A., Brown, X. Q., Wong, J. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+comparison+of+the+spread+area,+contractility,+and+migration+of+balb/c+3T3+fibroblasts+adhered+to+fibronectin-+and+RGD-modified+substrata.">Direct comparison of the spread area, contractility, and migration of balb/c 3T3 fibroblasts adhered to fibronectin- and RGD-modified substrata.</a> Biophys J. 87 (4), 2818-2827 (2004).</li><li>Reinhart-King, C. A., Dembo, M., Hammer, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+dynamics+and+mechanics+of+endothelial+cell+spreading.">The dynamics and mechanics of endothelial cell spreading.</a> Biophys J. 89, 676-689 (2005).</li><li>Stricker, J., Sabass, B., Schwarz, U. S., Gardel, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimization+of+traction+force+microscopy+for+micron-sized+focal+adhesions.">Optimization of traction force microscopy for micron-sized focal adhesions.</a> J. Phys: Condensed Matter. 22, 194104-194114 (2010).</li><li>Sabass, B., Gardel, M. L., Waterman, C. M., Schwarz, U. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+resolution+traction+force+microscopy+based+on+experimental+and+computational+advances.">High resolution traction force microscopy based on experimental and computational advances.</a> Biophys J. 94, 207-220 (2008).</li><li>Yeung, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+substrate+stiffness+on+cell+morphology,+cytoskeletal+structure,+and+adhesion.">Effects of substrate stiffness on cell morphology, cytoskeletal structure, and adhesion.</a> Cell Motil Cytoskeleton. 60 (1), 24-34 (2005).</li><li>Waterman-Storer, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microtubule/organelle+motility+assays.">Microtubule/organelle motility assays.</a> Curr Protoc Cell Biol. , 13.1.1-13.1.21 (1998).</li></ol>

No conflicts of interest declared.

The procedure described here for the setup of a traction force microscopy (TFM) experiment, along with the implementation of computational tracking routines (Sabass et al., 2008), allows for the quantification of cellular forces with micron-scale spatial resolution. To optimize the experimental protocol, it is critical to form a pure and uniform gel substrate with uniform coating of ECM ligand. We discuss potential pitfalls below:

Non-uniform Gel Surface or Tears:
<p class="jove...

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>3-aminopropyltrimethyoxysilane</td>
<td>&nbsp;</td>
<td>Aldrich</td>
<td>28, 177-8</td>
<td>&nbsp;</td>
<tr>
<td>40% Acrylamide</td>
<td>&nbsp;</td>
<td>BioRad</td>
<td>161-0140</td>
<td>&nbsp;</td>
<tr>
<td>2% Bis-acrylamide</td>
<td>&nbsp;</td>
<td>Fisher BioReagents</td>
<td>BP1404</td>
<td>&nbsp;</td>
<tr>
<td>TEMED</td>
<td>&nbsp;</td>
<td>Fisher BioReagents</td>
<td>BP 150-20</td>
<td>&nbsp;</td>
<tr>
<td>Ammonium persulfate</td>
<td>&nbsp;</td>
<td>Fisher Scientific</td>
<td>BP179</td>
<td>&nbsp;</td>
<tr>
<td>40nm fluorescent micro-spheres</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>F8789</td>
<td>&nbsp;</td>
<tr>
<td>Sulfo-SANPAH</td>
<td>&nbsp;</td>
<td>Pierce</td>
<td>22589</td>
<td>&nbsp;</td>
<tr>
<td>Confocal imaging chamber (RC-30)</td>
<td>&nbsp;</td>
<td>Warner Instruments</td>
<td>64-0320</td>
<td>&nbsp;</td>
<tr>
<td>Coverslip spinner</td>
<td>&nbsp;</td>
<td>Home-built</td>
<td>NA</td>
<td>&nbsp;</td>
<tr>
<td>Ultraviolet lamp CL1000</td>
<td>&nbsp;</td>
<td>UVP</td>
<td>95-0228-01</td>
<td>&nbsp;</td>
<tr>
<td>Stainless steel rack</td>
<td>&nbsp;</td>
<td>Electron Microscopy Sciences</td>
<td>72239-04</td>
<td>&nbsp;</td>
<tr>
<td>acryloyl-X, SE (6-((acryloyl)amino)hexanoic acid)</td>
<td>&nbsp;</td>
<td>Invitrogen
</td>
<td>A-20770</td>
<td>&nbsp;</td>
<tr>
<td>Hydrazine hydrate</td>
<td>&nbsp;</td>
<td>Sigma Aldrich</td>
<td>225819</td>
<td>&nbsp;</td>
<tr>
<td>Sodium meta-periodate</td>
<td>&nbsp;</td>
<td>Thermo Scientific</td>
<td>20504</td>
<td>&nbsp;</td>
<tr>
<td>Isopropanol</td>
<td>&nbsp;</td>
<td>Fisher Scientific</td>
<td>A416-4</td>
<td>&nbsp;</td>
<tr>
<td>Fibronectin</td>
<td>&nbsp;</td>
<td>Sigma-Aldrich</td>
<td>F2006</td>
<td>&nbsp;</td>
<tr>
<td>Collagen</td>
<td>&nbsp;</td>
<td>BD Biosciences</td>
<td>354236</td>
<td>&nbsp;</td>
<tr>
<td>Coverslips (#1.5)</td>
<td>&nbsp;</td>
<td>Corning</td>
<td>2940&#x2010;224</td>
<td>&nbsp;</td>
<tr>
<td>Glutaraldehyde</td>
<td>&nbsp;</td>
<td>Electron Microscopy Sciences</td>
<td>16120</td>
<td>&nbsp;</td>
<tr>
<td>Rain-X</td>
<td>&nbsp;</td>
<td>SOPUS Products</td>
<td>www.rainx.com</td>
<td>&nbsp;</td>
<tr>
<td>Acetic Acid</td>
<td>&nbsp;</td>
<td>Acros Organics</td>
<td>64-19-7</td>
<td>&nbsp;</td>		</tbody>
		</table>
		</div>

preparation of complaint matrices for quantifying cellular contraction

The regulation of cellular adhesion to the extracellular matrix (ECM) is essential for cell migration and ECM remodeling. Focal adhesions are macromolecular assemblies that couple the contractile F-actin cytoskeleton to the ECM. This connection allows for the transmission of intracellular mechanical forces across the cell membrane to the underlying substrate. Recent work has shown the mechanical properties of the ECM regulate focal adhesion and F-actin morphology as well as numerous physiological processes, including cell differentiation, division, proliferation and migration. Thus, the use of cell culture substrates has become an increasingly prevalent method to precisely control and modulate ECM mechanical properties.
To quantify traction forces at focal adhesions in an adherent cell, compliant substrates are used in conjunction with high-resolution imaging and computational techniques in a method termed traction force microscopy (TFM). This technique relies on measurements of the local magnitude and direction of substrate deformations induced by cellular contraction. In combination with high-resolution fluorescence microscopy of fluorescently tagged proteins, it is possible to correlate cytoskeletal organization and remodeling with traction forces.
Here we present a detailed experimental protocol for the preparation of two-dimensional, compliant matrices for the purpose of creating a cell culture substrate with a well-characterized, tunable mechanical stiffness, which is suitable for measuring cellular contraction. These protocols include the fabrication of polyacrylamide hydrogels, coating of ECM proteins on such gels, plating cells on gels, and high-resolution confocal microscopy using a perfusion chamber. Additionally, we provide a representative sample of data demonstrating location and magnitude of cellular forces using cited TFM protocols.

Watch this Scientific Journal Video about Preparation of Complaint Matrices for Quantifying Cellular Contraction at JoVE.com

Preparation of Complaint Matrices for Quantifying Cellular Contraction

In this video, we demonstrate the experimental techniques used to fabricate compliant, extracellular matrix (ECM) coated substrates suitable for cell culture, and which are amenable to traction force microscopy and observing effects of ECM stiffness on cell behavior.

The regulation of cellular adhesion to the extracellular matrix (ECM) is essential for cell migration and ECM remodeling.  Focal adhesions are ...

preparation-of-complaint-matrices-for-quantifying-cellular-contraction

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JoVE Journal

Bioengineering

17.7K Views.  University of Chicago. In questo video, dimostriamo le tecniche sperimentali utilizzate per fabbricare compatibile, della matrice extracellulare (ECM) substrati rivestiti adatto per colture cellulari e che sono suscettibili di microscopia a forza di trazione e di osservare gli effetti di rigidità ECM sul comportamento delle cellule.