@article {281,
	title = {Exploring the link between human embryonic stem cell organization and fate using tension-calibrated extracellular matrix functionalized polyacrylamide gels.},
	journal = {Methods Mol Biol},
	volume = {916},
	year = {2012},
	month = {2012},
	pages = {317-50},
	abstract = {<p>Human embryonic stem cell (hESc) lines are likely the in vitro equivalent of the pluripotent epiblast. hESc express high levels of the extracellular matrix (ECM) laminin integrin receptor α6β1 and consequently can adhere robustly and be propagated in an undifferentiated state on tissue culture plastic coated with the laminin rich basement membrane preparation, Matrigel, even in the absence of supporting fibroblasts. Such cultures represent a critical step in the development of more defined feeder free cultures of hESc; a goal deemed necessary for regenerative medical applications and have been used as the starting point in some differentiation protocols. However, on standard non-deformable tissue culture plastic hESc either fail or inadequately develop the structural/morphological organization of the epiblast in vivo. By contrast, growth of hESc on appropriately defined mechanically deformable polyacrylamide substrates permits recapitulation of many of these in vivo features. These likely herald differences in the precise nature of the integration of signal transduction pathways from soluble morphogens and represent an unexplored variable in hESc (fate) state space. In this chapter we describe how to establish viable hESc colonies on these functionalized polyacrylamide gels. We suggest this strategy as a prospective in vitro model of the genetics, biochemistry, and cell biology of pre- and early-gastrulation stage human embryos and the permissive and instructive roles that cellular and substrate mechanics might play in early embryonic cell fate decisions. Such knowledge should inform regenerative medical applications aimed at enabling or improving the differentiation of specific cell types from embryonic or induced embryonic stem cells.</p>
},
	keywords = {Acrylamides, Acrylic Resins, Calibration, Cell Culture Techniques, Cell Differentiation, Cell Polarity, Collagen, Crystallization, Drug Combinations, Elastic Modulus, Embryonic Stem Cells, Extracellular Matrix, Glutaral, Humans, Laminin, Ligands, Proteoglycans, Stress, Mechanical, Trypsin},
	issn = {1940-6029},
	doi = {10.1007/978-1-61779-980-8_24},
	author = {Lakins, Johnathon N and Chin, Andrew R and Weaver, Valerie M}
}
@article {361,
	title = {Integrin clustering is driven by mechanical resistance from the glycocalyx and the substrate.},
	journal = {PLoS Comput Biol},
	volume = {5},
	year = {2009},
	month = {2009 Dec},
	pages = {e1000604},
	abstract = {<p>Integrins have emerged as key sensory molecules that translate chemical and physical cues from the extracellular matrix (ECM) into biochemical signals that regulate cell behavior. Integrins function by clustering into adhesion plaques, but the molecular mechanisms that drive integrin clustering in response to interaction with the ECM remain unclear. To explore how deformations in the cell-ECM interface influence integrin clustering, we developed a spatial-temporal simulation that integrates the micro-mechanics of the cell, glycocalyx, and ECM with a simple chemical model of integrin activation and ligand interaction. Due to mechanical coupling, we find that integrin-ligand interactions are highly cooperative, and this cooperativity is sufficient to drive integrin clustering even in the absence of cytoskeletal crosslinking or homotypic integrin-integrin interactions. The glycocalyx largely mediates this cooperativity and hence may be a key regulator of integrin function. Remarkably, integrin clustering in the model is naturally responsive to the chemical and physical properties of the ECM, including ligand density, matrix rigidity, and the chemical affinity of ligand for receptor. Consistent with experimental observations, we find that integrin clustering is robust on rigid substrates with high ligand density, but is impaired on substrates that are highly compliant or have low ligand density. We thus demonstrate how integrins themselves could function as sensory molecules that begin sensing matrix properties even before large multi-molecular adhesion complexes are assembled.</p>
},
	keywords = {Algorithms, Computer Simulation, Extracellular Matrix, Glycocalyx, Integrins, Ligands, Protein Binding, Stress, Physiological, Substrate Specificity},
	issn = {1553-7358},
	doi = {10.1371/journal.pcbi.1000604},
	author = {Paszek, Matthew J and Boettiger, David and Weaver, Valerie M and Hammer, Daniel A}
}
