Generation and Characterization of MacGreen Mice, the Cfs1r-EGFP Transgenic Mice

Macrophage colony-stimulating factor (CSF-1) regulates the differentiation, proliferation, and survival of cells of the mononuclear phagocyte system. The activity of CSF-1 is mediated by the CSF-1 receptor (CSFlR, CD115) that is encoded by c-fms (Csf1r ) protooncogene. The c-fms gene is expressed in macrophage, trophoblast cell lineages, and to some extent granulocytes. A reporter gene construct containing 3.5-kb of 5′ flanking sequence and the downstream intron 2 of the c-fms gene directed expression of enhanced green fluorescent protein (EGFP) to cells expressing the c-fms gene including the macrophages and trophoblasts. EGFP was detected in trophoblasts from the earliest stage of implantation. During embryonic development, EGFP expression highlighted the large numbers of c-fms positive macrophages in most organs. These embryonic macrophages contribute to organogenesis and tissue remodeling. In adult c-fms EGFP transgenic mice, which have been called the MacGreen mice, EGFP expressed in all tissue macrophage populations and permitted convenient detection of tissue macrophages as well as facilitates their isolation from various tissues.