Xenbase Image ID: 159235

Fig. 2. Features of ESC self-organization and patterning. (A) A simple example of polarity-based self-organization. Dissociated ESCs on a surface coated with polymerized ECM proteins form a polarized epithelium, with cells exhibiting apical (green) and basolateral (orange) surfaces. (B) Sorting driven by the minimization of tissue surface energy. Cells with the strongest cell-cell interactions (based on adhesive energy or tissue tension) migrate toward the interior of a cell cluster, while those with the weakest cell-cell interactions migrate toward the exterior. (C) Lumen formation in ESCs. Cells embedded in a gel of polymerized ECM proteins polarize and form a spherical embryoid with a lumen at its center. The proteins actin and ezrin are enriched at the apical part of polarized cells. Microscopy image reproduced with permission (Taniguchi et al., 2015). (D) Mechanical properties affect cell differentiation and patterning. Shown is an example demonstrating that cells cultured on a softer surface have a higher propensity for mesodermal differentiation than those cultured on a stiff surface. (E) Geometric confinement may give rise to a signaling gradient. Shown is an example of the BMP4-induced differentiation of hESCs grown in colonies of different sizes. The cells sense BMP4 only at the edge of the colony (i.e. only the cells in between the two dotted circles are competent to receive the BMP4 signal), inducing the secretion of an inhibitor which, together with the BMP4, establishes a signaling gradient. The result is a radially symmetric pattern of gene expression resembling that of germ layer formation in gastrulation. As the signaling gradient is constant, the inner cell fates do not arise in small colonies. TE, trophectoderm. Microscopy images adapted with permission (Deglincerti et al., 2016b). Image published in: Simunovic M and Brivanlou AH (2017) Copyright © 2017. Image reproduced with permission of the publisher and the copyright holder. This is an Open Access article distributed under the terms of the Creative Commons Attribution License. Larger Image Printer Friendly View

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