Thus, these systems may represent a promising arena for the investigation of symmetry breaking, and the events that lead to the formation of the body axis from a symmetric embryo
Thus, these systems may represent a promising arena for the investigation of symmetry breaking, and the events that lead to the formation of the body axis from a symmetric embryo. sub-millimeter colonies. After 42 hours of BMP4 stimulation, cells form self-organized differentiation patterns in concentric radial domains, which express specific markers associated with the embryonic germ layers, reminiscent of gastrulating embryos. Our protocol takes 3 days; it uses commercial microfabricated slides (CYTOO), human laminin-521 (LN-521) as extra-cellular matrix coating, and either conditioned or chemically-defined medium (mTeSR). Differentiation patterns within individual colonies can be determined by immunofluorescence and analyzed with cellular resolution. Both the size of the micropattern and the type of medium affect the patterning outcome. The protocol is appropriate for personnel with basic stem cell culture training. This protocol describes a robust platform for quantitative analysis of the mechanisms associated with pattern formation at the onset of gastrulation. studies. A challenge of using hESCs to study development is that the differentiation must be made to resemble Metanicotine development as closely as possible, and, in particular, systems need to be developed in which hESCs differentiate in spatial patterns akin to those in the early embryo. Here we present a method for controlling the spatial organization of hESC differentiation patterns that are associated with embryonic gastrulation. Development of the method We initially analyzed the relationship between the TGF-? signaling and cell fate in a murine myoblast cell line, and showed that TGF-showed that TGF-cell line, different. We then explored the consequences of this mechanism in cell-fate decisions5,6. We sought to extend comparable methods to study signaling and fate decisions in hESCs, but Metanicotine were hampered by the inherent variability between cells. The response of cells to applied ligands varied within the colony and every colony had a different spatial pattern of signaling. As regular hESCs cultures present colonies of different sizes and shapes, we reasoned that variations in colony geometries likely underlie these variable colony-level responses. We therefore sought to control colony geometries. Methods to control the shape of single cells had previously been used to study the biophysics of cell shape, adhesion, and division7,8. Micropatterning technologies to spatially control extra-cellular matrix deposition and thus colony geometries on 2D surfaces had also been applied to hESCs where it was observed that colonies of different size Metanicotine gave rise to different proportions of cell fate upon differentiation9,10, however, spatial differentiation patterns were not observed. In our experiments, we found that micropatterned colonies treated with Bone Morphogenetic Protein 4 (BMP4) responded with particular spatial patterns of signaling that translated into cell fate patterns. These patterns of signaling involved both differential responses to the initial BMP4 stimulus as well as patterns of endogenous Nodal signaling that were shaped by the production of both the Nodal ligand and its feedback inhibitor Lefty11. Wnt signaling likely serves as a required intermediate between BMP4 and Nodal as Wnt ligands are targets of BMP4 signaling both in the mouse1 and in hESCs differentiated with BMP412. Comparison to other methods Here, we describe a protocol that takes advantage of commercially available micropatterned coverslips (Cytoo). These Rabbit polyclonal to ZNF101 are produced by first covering the culture surface with a cell-repellant substrate such as lysine-grafted polyethylene glycol13 and then selectively removing it using UV light or a plasma etch in a pattern defined by a mask. Homemade solutions using this technique can also yield satisfactory cell confinement14. An alternative method to produce the same results is usually microcontact printing, which is performed with an embossed stamp coated with an extracellular matrix of interest capable of mediating cellular attachment. When the stamp is usually pressed onto a slide, it deposits a cell-adherent coating in the desired pattern9,15. The uncoated areas may be backfilled with a passivating material to interfere with nonspecific attachment of cells. The stamps are made by spin coating polydimethylsiloxane (PDMS) elastomer over a negative mold made using standard photolithography or silicon etching. As commercial chips offer only a limited number of designs, it may be necessary to use homemade micropatterned chips for special applications: for example when alternative.