Lineage tracing origins of human innate lymphoid cells from hematopoietic precursors

Project summary Human natural killer (NK) cells are critical for control of viral infection and their importance for human health is underscored by the disease that results from dysregulated NK cell development or function. In the adult, NK cells are continuously generated from stem cells, making their generation an important process for human immunity. Despite the importance of this continuous generation, there is much that is still unknown about how stem cells with the potential to become any blood cell are directed to become an NK cell. This process is further complexified by the observation that myeloid progenitors can give rise to NK cells under certain conditions. Here we propose to address these questions using genetic ‘barcoding’ of human pluripotent stem cells combined with their differentiation to NK cell lineages. This experimental approach will be used to delineate the emergence of innate lymphoid cells from stem cells with single cell resolution. Aim 1 will optimize a novel genetic cell tracing system and use it to generate transcriptomic trajectories of NK cell differentiation from lymphoid or myeloid committed progenitors. Aim 2 will pair this reporter system with live cell imaging of cell dynamics as NK cells undergo differentiation to understand the dynamic interactions that give rise to human NK cells. Together, these aims will define the emergence of NK cells from multipotent progenitors and provide a mechanistic, single cell resolution understanding of how lymphoid and myeloid progenitors give rise to functionally mature innate lymphocytes.