title: Label-free identification of macrophage phenotype by fluorescence lifetime imaging microscopy.
abstract: Macrophages adopt a variety of phenotypes that are a reflection of the many functions they perform as part of the immune system. In particular, metabolism is a phenotypic trait that differs between classically activated, proinflammatory macrophages, and alternatively activated, prohealing macrophages. Inflammatory macrophages have a metabolism based on glycolysis while alternatively activated macrophages generally rely on oxidative phosphorylation to generate chemical energy. We employ this shift in metabolism as an endogenous marker to identify the phenotype of individual macrophages via live-cell fluorescence lifetime imaging microscopy (FLIM). We demonstrate that polarized macrophages can be readily discriminated with the aid of a phasor approach to FLIM, which provides a fast and model-free method for analyzing fluorescence lifetime images.
authors.affiliation: University of California Irvine, Department of Biomedical Engineering, 2412 Engineering Hall, Irvine, California 92697, United States.
authors.forename: Alba
authors.initials: A
authors.lastname: Alfonso-García
authors.affiliation: University of California Irvine, Department of Biomedical Engineering, 2412 Engineering Hall, Irvine, California 92697, United States.
authors.forename: Tim D
authors.initials: TD
authors.lastname: Smith
authors.affiliation: University of California Irvine, Department of Biomedical Engineering, 2412 Engineering Hall, Irvine, California 92697, United States.
authors.forename: Rupsa
authors.initials: R
authors.lastname: Datta
authors.affiliation: University of California Irvine, Department of Pharmacological Sciences, 2412 Engineering Hall, Irvine, California 92697, United States.
authors.forename: Thuy U
authors.initials: TU
authors.lastname: Luu
authors.affiliation: University of California Irvine, Department of Biomedical Engineering, 2412 Engineering Hall, Irvine, California 92697, United States.
authors.forename: Enrico
authors.initials: E
authors.lastname: Gratton
authors.affiliation: University of California Irvine, Department of Chemistry, 2412 Engineering Hall, Irvine, California 92697, United States.
authors.forename: Eric O
authors.initials: EO
authors.lastname: Potma
authors.affiliation: University of California Irvine, Department of Biomedical Engineering, 2412 Engineering Hall, Irvine, California 92697, United States.
authors.forename: Wendy F
authors.initials: WF
authors.lastname: Liu
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005260:Female; D006019:Glycolysis; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008264:Macrophages / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence / Q000379:methods*; D009243:NAD / Q000032:analysis / Q000378:metabolism; D010085:Oxidative Phosphorylation; D010641:Phenotype
chemical_list: D009243:NAD