Establishing an in vitro model for embryonic patterning using a novel micropatterning system (360G-Wellcome-110151_Z_15_Z)

An in vitro micropatterning system (MPS) was developed, using human ESCs, which apparently mimics patterning within the embryo. This 'embryo in a dish' develops a presumptive primitive streak, introducing the possibility of studying gastrulation dynamically in vitro. This MPS gastrulation model resembles 3D organoids emerging for a number of systems and enables signalling manipulation in time and 3D space. While this system was established in human, it cannot be validated by comparisons with in vivo human development. The mouse model represents an essential bridge between pluripotent cell cultures and the embryo. I will establish the MPS in mouse and compare the expression of lineage markers in the MPS directly to mouse embryos to ask whether this system recapitulates in utero development. I will use the MPS to compare mouse and human development and analyse the basis of patterning defects in mouse mutants. I will use transcription factor and signalling pathway fluorescent reporters to map the spatial and temporal requirements of BMP, Activin/Nodal and Wnt pathways for patterning at a quantitative single cell resolution in real-time. Using this data, in collaboration with the Siggia lab, mathematical models will be generated and tested to predict the phenotypic outcome of signalling combinations.