Large-scale production of human iPSC-derived macrophages for drug screening

Tissue resident macrophages are key players in inflammatory processes and their activation and functionality is crucial in health and disease. Diseases associated with alterations in homeostasis or dysregulation of the innate immune system are numerous and include allergic reactions, autoimmune diseases as well as cancer. Hence, these cells are of high interest in drug development. Currently, the main sources of macrophages used in drug development are still primary cells isolated from blood or tissue, or immortalized cell lines (e.g. THP-1). Here, we describe an improved method for large-scale production of tissue resident macrophages from induced pluripotent stem cells (iPSC) in unprecedented yields. For this, iPSC-derived macrophages are thoroughly characterized to confirm their cell identity and thus their suitability for screening purposes. We demonstrate that this method to generate macrophages from iPSC overcomes the limitations of using primary cells, i.e. donor variability and limited availability of large cell numbers. Notably, the cells recapitulate key functional characteristics, including cytokine release, phagocytosis and migration. Genetic modifications can be introduced at the macrophage progenitor stage, so this methodology will facilitate the generation of reporters and gain- and loss-of-function mutants in an isogenetic background, essential assets for target validation. Overall design: Monocytes from primary cells or macrophage progenitors from iPSCs were differentiated into M0 macrophages (MCSF), M1 macrophages (GMCSF, INFG), and M2 macrophages (MCSF, IL4). iPSC-derived monocytes were also differentiated into microglia cells (CD34, GMCSF). 5 replicates were sequenced for each cell type and 5 additional samples were sequenced for primary and iPSC monocytes in a second run.