IMECs support macrophage differentiation from hematopoietic progenitors. (A) Schematic representation of hematopoietic progenitors evaluated and the time of emergence of macrophage colonies (right). HSPC indicates hematopoietic stem/progenitor cell; G/CMP, granulocyte-macrophage and common myeloid progenitor; and MEP, megakaryocyte-erythroid progenitor. Arrows indicate colonies. Scale bar, 200 μm. (B) Colony cell number at day 28 of cocultures was normalized to the initial number of progenitor cells plated (n = 6). (C) Colony cells from all progenitors moderately display M2 macrophage markers but lack M1 markers. Ctrl indicates colony cells from the coculture of whole bone marrow (WBM) cells and IMECs (n = 6). (D) Colonies from all progenitors expressed CD206/Mrc1 (M2 macrophage marker, green) and F4/80 (pan macrophage marker, red). Colonies shown are from d14 coculture. DAPI indicates staining for nucleus (blue). Scale bar, 100 μm.