title: Inverse-power-law behavior of cellular motility reveals stromal-epithelial cell interactions in 3D co-culture by OCT fluctuation spectroscopy.
abstract: The progression of breast cancer is known to be affected by stromal cells within the local microenvironment. Here we study the effect of stromal fibroblasts on the in-place motions (motility) of mammary epithelial cells within organoids in 3D co-culture, inferred from the speckle fluctuation spectrum using optical coherence tomography (OCT). In contrast to Brownian motion, mammary cell motions exhibit an inverse power-law fluctuation spectrum. We introduce two complementary metrics for quantifying fluctuation spectra: the power-law exponent and a novel definition of the motility amplitude, both of which are signal- and position-independent. We find that the power-law exponent and motility amplitude are positively (p<0.001) and negatively (p<0.01) correlated with the density of stromal cells in 3D co-culture, respectively. We also show how the hyperspectral data can be visualized using these metrics to observe heterogeneity within organoids. This constitutes a simple and powerful tool for detecting and imaging cellular functional changes with OCT.
authors.affiliation: Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255; Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7513; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7295.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Oldenburg
authors.affiliation: Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255; Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7513.
authors.forename: Xiao
authors.initials: X
authors.lastname: Yu
authors.affiliation: Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255.
authors.forename: Thomas
authors.initials: T
authors.lastname: Gilliss
authors.affiliation: Department of Computer Science, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3175.
authors.forename: Oluwafemi
authors.initials: O
authors.lastname: Alabi
authors.affiliation: Department of Computer Science, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3175; Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255.
authors.forename: Russell M
authors.initials: RM
authors.lastname: Taylor
authors.affiliation: Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7295; Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7435.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Troester