Bioengineering embryo models

Stem cell-based embryo models, which recapitulate symmetry breaking, pattern formation and tissue morphogenesis during early development, provide promising experimental tools to study the development of mammalian species, including humans. Despite considerable progress in embryo modelling using cultured stem cells, generating embryo models with high fidelity, efficiency, controllability, and in vivo-like cellular organization and tissue architecture remains challenging. This is largely due to intrinsic variabilities in self-organization and differentiation of mammalian stem cells in uncontrolled culture environments. In this Review, we argue that bioengineering tools, which are powerful for controlling topological boundaries and dynamic chemical and mechanical signals, can efficiently guide symmetry breaking, pattern formation, tissue morphogenesis and tissue–tissue interactions. We discuss pattern formation and morphogenesis during embryonic development and examine different embryo models to highlight the importance of bioengineering strategies in developing models with improved efficiency, reproducibility, controllability, complexity and in vivo relevance.