Abstract 2785: Metabolic autofluorescence microscopy of 3D microscale macrophage-tumor co-cultures

• Published in: Cancer research (Chicago, Ill.) Ill.), 2019-07, Vol.79 (13_Supplement), p.2785-2785
• Main Authors: Heaster, Tiffany M., Yu, Jiaquan, Edman, Margaret, Beebe, David J., Skala, Melissa C.
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM2019-2785

Macrophages are ideal treatment targets due to their tumor-regulatory functions and high infiltration in the tumor microenvironment (TME). However, macrophage heterogeneity prevents effective therapeutic reprogramming. Macrophages have high plasticity and adopt phenotypes with diverse behavior and metabolism. The complex TME can drive this plasticity but is not well understood. Standard functional assays (e.g. flow cytometry, ELISA) lack sensitivity to heterogeneous cell populations. Also, their destructive sample processing limits spatial and temporal assessment. Thus, nondestructive, single cell imaging and analysis tools are needed to study macrophage heterogeneity within the TME. Optical metabolic imaging (OMI) measures two-photon excited fluorescence from the coenzymes NAD(P)H and FAD to resolve cellular metabolism within intact, 3D samples. The optical redox ratio (NAD(P)H intensity/FAD intensity) and fluorescence lifetimes reflect cell redox state and intracellular protein binding, respectively. Previous studies have shown that OMI detects spatial and temporal changes in stromal cells across in vivo and 3D in vitro models. Microscale models closely mimic the TME, are high throughput, and enable precise environmental control. Thus, microenvironmental stimulation of macrophage polarization and migration was mimicked in 3D microscale cultures of mouse macrophages (RAW264.7) and mammary carcinoma cells (PyVMT) in a collagen matrix. OMI captured redox ratio, NAD(P)H and FAD mean lifetime (τm) changes in mono-cultured and co-cultured macrophages 24-72 hours post-seeding. Intensity and lifetime volumes of macrophage layers further assessed metabolic changes in macrophages during migration. Co-cultured macrophages exhibited significantly increased (p