Abstract 3702: Quantitative imaging of metabolic changes in macrophage subsets

• Published in: Cancer research (Chicago, Ill.) Ill.), 2017-07, Vol.77 (13_Supplement), p.3702-3702
• Main Authors: Heaster, Tiffany M., Elion, David L., Cook, Rebecca S., Skala, Melissa C.
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM2017-3702

Macrophages play an important role in tumor therapeutic response. However, current methods cannot image heterogeneities in macrophage activity on a single-cell level over time within intact, living samples. Macrophage metabolism is closely linked to macrophage function, as M1-like macrophages rely on aerobic glycolysis and M2-like macrophages rely on fatty acid oxidation and oxidative phosphorylation. Thus, we propose to develop optical metabolic imaging (OMI) using two-photon microscopy to monitor cell-level changes in macrophage polarization and functional activity. OMI exploits the auto-fluorescence intensities and lifetimes of the metabolic co-enzymes NAD(P)H and FAD, and has been previously used to dynamically image in vivo tumors with cell-level resolution. The optical redox ratio (fluorescence intensity of NAD(P)H divided by FAD) provides a global measure of redox balance within individual cells. The fluorescence lifetimes of NAD(P)H and FAD provide information in protein-binding activities in metabolic reactions. OMI was used to monitor metabolic changes in macrophages on a single-cell level during polarization and after metabolic perturbations. RAW 264.7 macrophages were stimulated towards an M1- or M2-like phenotype, and imaged with OMI at 24, 48, and 72 hours post-polarization. M1- and M2-like macrophages exhibited significant differences (p