Migratory Neural Crest Cells Phagocytose Dead Cells in the Developing Nervous System

During neural tube closure and spinal cord development, many cells die in both the central and peripheral nervous systems (CNS and PNS, respectively). However, myeloid-derived professional phagocytes have not yet colonized the trunk region during early neurogenesis. How apoptotic cells are removed from this region during these stages remains largely unknown. Using live imaging in zebrafish, we demonstrate that neural crest cells (NCCs) respond rapidly to dying cells and phagocytose cellular debris around the neural tube. Additionally, NCCs have the ability to enter the CNS through motor exit point transition zones and clear debris in the spinal cord. Surprisingly, NCCs phagocytosis mechanistically resembles macrophage phagocytosis and their recruitment toward cellular debris is mediated by interleukin-1β. Taken together, our results reveal a role for NCCs in phagocytosis of debris in the developing nervous system before the presence of professional phagocytes. [Display omitted] •Neural crest cells phagocytose debris during early development in the PNS•They migrate into the spinal cord through motor exit points to clear CNS debris•Their recruitment toward debris is mediated by interleukin-1β signaling•Maturation of neural crest phagosomes is similar to that in professional phagocytes Neural crest cells clear cellular debris left behind from cell death that occurs during early embryonic development, thus revealing an unexpected source of phagocytic activity prior to the arrival of professional phagocytes in the developing zebrafish nervous system.