A Modular Platform for Differentiation of Human PSCs into All Major Ectodermal Lineages.

Directing the fate of human pluripotent stem cells (hPSCs) into different lineages requires variable starting conditions and components with undefined activities, introducing inconsistencies that confound reproducibility and assessment of specific perturbations. Here we introduce a simple, modular protocol for deriving the four main ectodermal lineages from hPSCs. By precisely varying FGF, BMP, WNT, and TGFβ pathway activity in a minimal, chemically defined medium, we show parallel, robust, and reproducible derivation of neuroectoderm, neural crest (NC), cranial placode (CP), and non-neural ectoderm in multiple hPSC lines, on different substrates independently of cell density. We highlight the utility of this system by interrogating the role of TFAP2 transcription factors in ectodermal differentiation, revealing the importance of TFAP2A in NC and CP specification, and performing a small-molecule screen that identified compounds that further enhance CP differentiation. This platform provides a simple stage for systematic derivation of the entire range of ectodermal cell types.