Box: Methods of creating 2D micropatterned ESC colonies.

There are several ways of controlling the geometry of cell colonies. One common approach comprises casting a mold using an elastomeric material such as poly(dimethylsiloxane) (PDMS). The elastomer is coated with an ECM protein, such as laminin, which is then mechanically transferred like a stamp onto the dish [32] (see Box figure, a). Other approaches involve directly manipulating the surface by etching the surface with UV. In the depicted example, (see Box figure, b), the laminin is deposited on the PDMS-coated surface, covered with a photomask in the shape of desired patterns, then the laminin covering the remaining surface is etched away with UV [15].