Directed Differentiation of Human Pluripotent Stem Cells to Microglia

Microglia, the immune cells of the brain, are crucial to proper development and maintenance of the CNS, and their involvement in numerous neurological disorders is increasingly being recognized. To improve our understanding of human microglial biology, we devised a chemically defined protocol to generate human microglia from pluripotent stem cells. Myeloid progenitors expressing CD14/CX3CR1 were generated within 30 days of differentiation from both embryonic and induced pluripotent stem cells (iPSCs). Further differentiation of the progenitors resulted in ramified microglia with highly motile processes, expressing typical microglial markers. Analyses of gene expression and cytokine release showed close similarities between iPSC-derived (iPSC-MG) and human primary microglia as well as clear distinctions from macrophages. iPSC-MG were able to phagocytose and responded to ADP by producing intracellular Ca2+ transients, whereas macrophages lacked such response. The differentiation protocol was highly reproducible across several pluripotent stem cell lines. •Efficient protocol to generate human microglia from PSCs•iPSC-derived microglia have ramified morphology and motile processes•Expression and cytokine profiles of iPSC-derived microglia resemble primary microglia•iPSC-derived microglia can phagocytose beads and respond to ADP Douvaras and colleagues generated microglia from pluripotent stem cells using a chemically defined protocol through a myeloid progenitor. iPSC-derived microglia showed highly motile processes, were able to phagocytose and responded to ADP with calcium transients. Microglial identity was further confirmed by gene expression analysis comparing multiple iPSC-derived microglia samples with primary microglia and peripheral blood or other tissue-specific macrophages.