@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 = {

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.

}, 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 {346, title = {Effect of substrate stiffness and PDGF on the behavior of vascular smooth muscle cells: implications for atherosclerosis.}, journal = {J Cell Physiol}, volume = {225}, year = {2010}, month = {2010 Oct}, pages = {115-22}, abstract = {

Vascular disease, such as atherosclerosis, is accompanied by changes in the mechanical properties of the vessel wall. Although altered mechanics is thought to contribute to disease progression, the molecular mechanisms whereby vessel wall stiffening could promote vascular occlusive disease remain unclear. It is well known that platelet-derived growth factor (PDGF) is a major stimulus for the abnormal migration and proliferation of vascular smooth muscle cells (VSMCs) and contributes critically to vascular disease. Here we used engineered substrates with tunable mechanical properties to explore the effect of tissue stiffness on PDGF signaling in VSMCs as a potential mechanism whereby vessel wall stiffening could promote vascular disease. We found that substrate stiffness significantly enhanced PDGFR activity and VSMC proliferation. After ligand binding, PDGFR followed distinct routes of activation in cells cultured on stiff versus soft substrates, as demonstrated by differences in its intensity and duration of activation, sensitivity to cholesterol extracting agent, and plasma membrane localization. Our results suggest that stiffening of the vessel wall could actively promote pathogenesis of vascular disease by enhancing PDGFR signaling to drive VSMC growth and survival.

}, keywords = {Acrylic Resins, Animals, Atherosclerosis, Cattle, Cell Culture Techniques, Cell Movement, Cell Proliferation, Cells, Cultured, Elasticity, Muscle, Smooth, Vascular, Myocytes, Smooth Muscle, Platelet-Derived Growth Factor, Receptors, Platelet-Derived Growth Factor}, issn = {1097-4652}, doi = {10.1002/jcp.22202}, author = {Brown, Xin Q and Bartolak-Suki, Erzsebet and Williams, Corin and Walker, Mathew L and Weaver, Valerie M and Wong, Joyce Y} } @article {511, title = {Death in the third dimension: apoptosis regulation and tissue architecture.}, journal = {Curr Opin Genet Dev}, volume = {14}, year = {2004}, month = {2004 Feb}, pages = {71-80}, abstract = {

Tissue development, homeostasis and tumor pathogenesis all depend upon a complex dialogue between multiple cell types operating within a dynamic three-dimensional (3D) tissue extracellular matrix microenvironment. A major issue is whether the spatial organization of a cell within this 3D tissue microenvironment could modulate cell responsiveness to regulate cell fate decisions such as survival, and if so how. Classic developmental model systems and transgenic animals are instructive but pose special challenges for investigators conducting signaling studies and biochemical assays in tissues. As an alternative, 3D culture model systems exist in which cell-adhesion dependent tissue architecture, heterotypic cell-cell interactions and tissue differentiation can be recapitulated with good fidelity. 3D cell culture models are slowly revealing how tissue architecture can dramatically influence how a cell responds to exogenous stimuli to modify its apoptotic behavior and hence should prove instrumental for identifying novel cell death pathways.

}, keywords = {Apoptosis, Cell Adhesion, Cell Culture Techniques, Extracellular Matrix, Gene Expression Regulation, Homeostasis, Models, Biological}, issn = {0959-437X}, doi = {10.1016/j.gde.2003.12.005}, author = {Zahir, Nastaran and Weaver, Valerie M} }