title: In vivo detection of macrophage recruitment in hind-limb ischemia using a targeted near-infrared fluorophore.
abstract: Macrophages are an essential component of the immune system and have protective and pathogenic functions in various diseases. Imaging of macrophages in vivo could furnish new tools to advance evaluation of disease and therapies. Critical limb ischemia is a disease in which macrophages have considerable pathogenic roles, and are potential targets for cell-based immunotherapy. We sought to develop a new near-infrared fluorescence (NIRF) imaging probe to target macrophages specifically in vivo in various pathological states, including hind-limb ischemia. We rapidly screened the photostable cyanine-based NIRF library against different blood cell lines. The identified monocyte/macrophage-selective hit was tested in vitro in live-cell labeling assay. Non-invasive NIRF imaging was performed with murine models of paw inflammation by lipopolysaccharide challenge and hind-limb ischemia with femoral artery ligation. in vivo macrophage targeting was further evaluated using intravital microscopy with Csf1r-EGFP transgenic mice and immunofluorescent staining with macrophage-specific markers. We discovered MF800, a Macrophage-specific near-infrared Fluorophore, which showed selective live-cell imaging performance in a panel of cell lines and primary human blood samples. MF800 outperforms the clinically-available NIRF contrast agent ICG for in vivo specificity in paw inflammation and hind-limb ischemia models. We observed a marked overlap of MF800-labeled cells and EGFP-expressing macrophages in intravital imaging of Csf1r-EGFP transgenic mice. In the histologic analysis, MF800-positive cells also expressed the macrophage markers CD68 and CD169. NIRF imaging showcased the potential of using MF800 to understand macrophage behavior in vivo, characterize macrophage-associated diseases, and may help in assessing therapeutic responses in the clinic.
authors: Smart Humanity Convergence Center, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, Korea; Department of Chemistry, National University of Singapore, Singapore, Singapore.
authors: Jung Sun
authors: JS
authors: Yoo
authors: Department of Chemistry, National University of Singapore, Singapore, Singapore.
authors: Raj Kumar
authors: RK
authors: Das
authors: Laboratory of Bioimaging Probe Development, Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, Singapore.
authors: Zhi Yen
authors: ZY
authors: Jow
authors: Department of Chemistry, National University of Singapore, Singapore, Singapore; Laboratory of Bioimaging Probe Development, Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, Singapore.
authors: Young-Tae
authors: YT
authors: Chang
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007211:Indoles / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D007249:Inflammation / Q000000981:diagnostic imaging; D007511:Ischemia / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D007866:Leg; D008264:Macrophages / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D011859:Radiography; D019265:Spectroscopy, Near-Infrared
chemical_list: D005456:Fluorescent Dyes; D007211:Indoles; C000602791:MF800 compound