Abstract 2748: Monitoring cellular metabolic activity by non-invasive endogenous fluorescence imaging
Authors: Seppa Isabelle , Xie Maggie , Xu Min , Phelan Shelley A. 
Published: September 2020

Abstract
Standard histopathology procedure requires multiple steps, including embedding, sectioning, staining, mounting, and analysis. In contrast, label-free computational staining of tissue uses chemometric fluorescence to quantify native chromophores such as FAD, NADH, tryptophan, and elastin. Some of these measurements can also correlate with biochemical alternations in cancer. In this study, we investigate whether endogenous fluorescence can measure cellular metabolism in MCF-10A cells. This is part of an NSF-funded interdisciplinary research project.Our experimental design involves parallel experiments using either end-point molecular assays or endogenous fluorescence. MCF10A normal breast epithelial cells were cultured under three conditions: growth medium, serum-deprived, and serum-deprived followed by serum stimulation. For endogenous fluorescence measurements, treated MCF-10A cells were imaged with epi-fluorescence and DIC microscopy. Each cell was first delineated with its DIC image, and its endogenous fluorescence intensities were obtained from the corresponding fluorescence images using ImageJ. The fluorescence intensity at the Green channel excited under blue light serves as the proxy for the concentration of flavin adenine dinucleotide (FAD), a marker for cellular metabolism. A significant difference in cellular FAD was observed between serum-deprived and re-stimulated conditions, while no significant differences were observed between any other conditions, potentially due to the reduced statistical power with the smaller sample sizes. The molecular end-point assay run in parallel is a glucose uptake assay using the 2-DG glucose analog. Our results demonstrate a reduction in cellular glucose uptake in serum-deprived MCF-10A cells, as compared to the serum-stimulated condition. We also found a significant reduction in glucose uptake in the serum-deprived condition compared to the re-stimulated condition. Based on these results, a similar trend of decreased cellular metabolism was seen between serum-deprived and re-stimulated MCF10A cells. While the glucose uptake assay and endogenous fluorescence imaging can both measure cellular metabolism, endogenous fluorescence imaging is noninvasive and further reveals significant heterogeneity in the shape and metabolic rate of cells under each individual growth conditions. Additional experiments are currently underway to verify the accuracy and consistency of this methodology, as well as its application in distinguishing cancerous from non-cancerous cells. This will establish a solid foundation for label-free computational staining based on chemometric endogenous fluorescence, and could provide an important new approach for non-invasive cancer cell characterization.
Citation Format: Isabelle Seppa, Maggie Xie, Min Xu, Shelley A. Phelan. Monitoring cellular metabolic activity by non-invasive endogenous fluorescence imaging [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2748.