Acquisition of cell migration defines NK cell differentiation from hematopoietic stem cell precursors

Abstract

Human natural killer (NK) cells are generated from CD34+ precursors and can be differentiated in vitro by co-culture with developmentally supportive stromal cells. Despite the requirement for stromal cell contact in this process, the nature of these contacts has been poorly defined. We have previously identified a requirement for NK cell signaling receptors associated with terminal maturation in NK cell migration. However, the relationship between NK cell migration and differentiation is still unclear. Here, we perform continuous long-term imaging and tracking of NK cell progenitors undergoing in vitro differentiation. We demonstrate that NK cell precursors can be tracked over long time periods on the order of weeks by utilizing phase-contrast microscopy, and show that these cells acquire increasing motility as they mature. Additionally, we observe that NK cells display a more heterogeneous range of migratory behaviors at later stages of development, with the acquisition of complex modes of migration that are associated with terminal maturation. Together these data demonstrate previously unknown migratory behaviors of innate lymphocytes undergoing lineage differentiation revealed by long-term imaging and analysis workflows.