1. Aggregate preparation for measurement of tissue surface tension. 
For adherent cells, spheroids can be formed by using either the hanging drop method or by generating a coherent sheet of cells that can then be cut into 1 mm fragments.
Aggregate formation by the hanging drop method:
<ol>
<li>Near-confluent adherent cell cultures should be grown to 90% confluence, whereupon monolayers should be rinsed twice with PBS. After draining well, add 2 mls (for 100 mm plates...

<ol>
	<li>Foty, R. A., Forgacs, G., Pfleger, C. M., Steinberg, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liquid+properties+of+embryonic+tissues:+Measurement+of+interfacial+tensions.">Liquid properties of embryonic tissues: Measurement of interfacial tensions.</a> Phys Rev Lett. 72, 2298-2301 (1994).</li><li>Foty, R. A., Pfleger, C. M., Forgacs, G., Steinberg, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+tensions+of+embryonic+tissues+predict+their+mutual+envelopment+behavior.">Surface tensions of embryonic tissues predict their mutual envelopment behavior.</a> Development. 122, 1611-1620 (1996).</li><li>Schotz, E. -. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+differences+in+tissue+surface+tension+influence+zebrafish+germ+layer+positioning.">Quantitative differences in tissue surface tension influence zebrafish germ layer positioning.</a> HFSP Journal. 2, 42-56 (2008).</li><li>Jia, D., Dajusta, D., Foty, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+surface+tensions+guide+in+vitro+self-assembly+of+rodent+pancreatic+islet+cells.">Tissue surface tensions guide in vitro self-assembly of rodent pancreatic islet cells.</a> Dev Dyn. 236, 2039-2049 (2007).</li><li>Schwarz, M. A., Zheng, H., Legan, S., Foty, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lung+Self-Assembly+is+Modulated+by+Tissue+Surface+Tensions.">Lung Self-Assembly is Modulated by Tissue Surface Tensions.</a> Am J Respir Cell Mol Biol. , (2010).</li><li>Ryan, P. L., Foty, R. A., Kohn, J., Steinberg, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+spreading+on+implantable+substrates+is+a+competitive+outcome+of+cell-cell+vs.+cell-substratum+adhesivity.">Tissue spreading on implantable substrates is a competitive outcome of cell-cell vs. cell-substratum adhesivity.</a> Proc Natl Acad Sci U S A. 98, 4323-4327 (2001).</li><li>Foty, R. A., Steinberg, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+differential+adhesion+hypothesis:+a+direct+evaluation.">The differential adhesion hypothesis: a direct evaluation.</a> Dev Biol. 278, 255-263 (2005).</li><li>Robinson, E. E., Foty, R. A., Corbett, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fibronectin+matrix+assembly+regulates+alpha5beta1-mediated+cell+cohesion.">Fibronectin matrix assembly regulates alpha5beta1-mediated cell cohesion.</a> Mol Biol Cell. 15, 973-981 (2004).</li><li>Robinson, E. E., Zazzali, K. M., Corbett, S. A., Foty, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=alpha5beta1+integrin+mediates+strong+tissue+cohesion.">alpha5beta1 integrin mediates strong tissue cohesion.</a> J Cell Sci. 116, 377-386 (2003).</li><li>Winters, B. S., Raj, B. K., Robinson, E. E., Foty, R. A., Corbett, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+culture+regulates+Raf-1+expression+to+modulate+fibronectin+matrix+assembly.">Three-dimensional culture regulates Raf-1 expression to modulate fibronectin matrix assembly.</a> Mol Biol Cell. 17, 3386-3396 (2006).</li><li>Caicedo-Carvajal, C. E., Shinbrot, T., Foty, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alpha5beta1+integrin-fibronectin+interactions+specify+liquid+to+solid+phase+transition+of+3D+cellular+aggregates.">Alpha5beta1 integrin-fibronectin interactions specify liquid to solid phase transition of 3D cellular aggregates.</a> PLoS One. 5, e11830-e11830 (2010).</li><li>Foty, R. A., Steinberg, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+tumor+cell+cohesion+and+suppression+of+invasion+by+E-+or+P-cadherin.">Measurement of tumor cell cohesion and suppression of invasion by E- or P-cadherin.</a> Cancer Res. 57, 5033-5036 (1997).</li><li>Foty, R. A., Corbett, S. A., Schwarzbauer, J. E., Steinberg, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dexamethasone+up-regulates+cadherin+expression+and+cohesion+of+HT-1080+human+fibrosarcoma+cells.">Dexamethasone up-regulates cadherin expression and cohesion of HT-1080 human fibrosarcoma cells.</a> Cancer Res. 58, 3586-3589 (1998).</li><li>Winters, B. S., Shepard, S. R., Foty, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biophysical+measurement+of+brain+tumor+cohesion.">Biophysical measurement of brain tumor cohesion.</a> Int J Cancer. 114, 371-379 (2005).</li><li>Foty, R. A., Cummings, K. B., Ward, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+surface+tensiometry:+a+novel+technique+for+predicting+invasive+potential+of+prostate+tumors+based+on+tumor+cell+aggregate+cohesivity+in+vitro.">Tissue surface tensiometry: a novel technique for predicting invasive potential of prostate tumors based on tumor cell aggregate cohesivity in vitro.</a> Surgical Forum L. , 707-708 (1999).</li><li>Folkman, J., Moscona, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+cell+shape+in+growth+control.">Role of cell shape in growth control.</a> Nature. 273, 345-349 (1978).</li><li>Foty, R. A., Forgacs, G., Pfleger, C. M., Steinberg, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liquid+properties+of+embryonic+tissues:+Measurement+of+interfacial+tensions.">Liquid properties of embryonic tissues: Measurement of interfacial tensions.</a> Physical Review Letters. 72, 2298-2301 (1994).</li><li>Guevorkian, K., Colbert, M. J., Durth, M., Dufour, S., Brochard-Wyart, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aspiration+of+biological+viscoelastic+drops.">Aspiration of biological viscoelastic drops.</a> Phys Rev Lett. 104, 218101-218101 (2010).</li></ol>

No conflicts of interest declared.

Measuring aggregate cohesion by TST is relatively straightforward. There are, however, key steps that must be mastered in order to generate useable TST data; 1) aggregates must be "healthy". This can be controlled by ensuring that aggregate formation begins with cells that are at optimal confluence prior to detachment. Aggregate size and time in culture must also be controlled to minimize the development of a necrotic core within the aggregate; 2) Another parameter that can influence TST measurements is the degree of adh...

<ul>
	<li>water bath/shaker (New Brunswick Scientific, Edison, NJ)</li> 
	<li>10 ml round-bottom flasks (Belco, Vineland, NJ)</li>
</ul>

measurement of aggregate cohesion by tissue surface tensiometry

Rigorous measurement of intercellular binding energy can only be made using methods grounded in thermodynamic principles in systems at equilibrium. We have developed tissue surface tensiometry (TST) specifically to measure the surface free energy of interaction between cells. The biophysical concepts underlying TST have been previously described in detail1,2. The method is based on the observation that mutually cohesive cells, if maintained in shaking culture, will spontaneously assemble into clusters. Over time, these clusters will round up to form spheres. This rounding-up behavior mimics the behavior characteristic of liquid systems. Intercellular binding energy is measured by compressing spherical aggregates between parallel plates in a custom-designed tissue surface tensiometer. The same mathematical equation used to measure the surface tension of a liquid droplet is used to measure surface tension of 3D tissue-like spherical aggregates. The cellular equivalent of liquid surface tension is intercellular binding energy, or more generally, tissue cohesivity. Previous studies from our laboratory have shown that tissue surface tension (1) predicts how two groups of embryonic cells will interact with one another1-5, (2) can strongly influence the ability of tissues to interact with biomaterials6, (3) can be altered not only through direct manipulation of cadherin-based intercellular cohesion7, but also by manipulation of key ECM molecules such as FN8-11 and 4) correlates with invasive potential of lung cancer12, fibrosarcoma13, brain tumor14 and prostate tumor cell lines15. In this article we will describe the apparatus, detail the steps required to generate spheroids, to load the spheroids into the tensiometer chamber, to initiate aggregate compression, and to analyze and validate the tissue surface tension measurements generated.

Watch this Scientific Journal Video about Measurement of Aggregate Cohesion by Tissue Surface Tensiometry at JoVE.com

Measurement of Aggregate Cohesion by Tissue Surface Tensiometry

We describe a method of measuring binding energy, expressible as tissue surface tension, between cells within 3D tissue-like aggregates. Differences in tissue surface tension have been demonstrated to correlate with invasiveness of lung, muscle, and brain tumors, and are fundamental determinants of establishing spatial relationships between different cell types.

Rigorous measurement of intercellular binding energy can only be made using methods grounded in thermodynamic principles in systems at equilibrium.  We ...

measurement-of-aggregate-cohesion-by-tissue-surface-tensiometry

Research

JoVE Journal

Bioengineering

12.5K Görüntüleme.  UMDNJ-Robert Wood Johnson Medical School. Biz 3D doku gibi agrega içinde hücreleri arasında, bağlayıcı enerji, doku yüzey gerilimi olarak ifade ölçme yöntemi açıklanmaktadır. , Akciğer, kas, ve beyin tümörleri invazivliğini ile ilişkili doku yüzey gerilimi farklar göstermiştir ve farklı hücre türleri arasındaki mekansal ilişkilerin kurulması temel belirleyicileri olmuştur.