title: Single-Cell Analysis of [18F]Fluorodeoxyglucose Uptake by Droplet Radiofluidics.
abstract: Radiolabels can be used to detect small biomolecules with high sensitivity and specificity without interfering with the biochemical activity of the labeled molecule. For instance, the radiolabeled glucose analogue, [18F]fluorodeoxyglucose (FDG), is routinely used in positron emission tomography (PET) scans for cancer diagnosis, staging, and monitoring. However, despite their widespread usage, conventional radionuclide techniques are unable to measure the variability and modulation of FDG uptake in single cells. We present here a novel microfluidic technique, dubbed droplet radiofluidics, that can measure radiotracer uptake for single cells encapsulated into an array of microdroplets. The advantages of this approach are multiple. First, droplets can be quickly and easily positioned in a predetermined pattern for optimal imaging throughput. Second, droplet encapsulation reduces cell efflux as a confounding factor, because any effluxed radionuclide is trapped in the droplet. Last, multiplexed measurements can be performed using fluorescent labels. In this new approach, intracellular radiotracers are imaged on a conventional fluorescence microscope by capturing individual flashes of visible light that are produced as individual positrons, emitted during radioactive decay, traverse a scintillator plate placed below the cells. This method is used to measure the cell-to-cell heterogeneity in the uptake of tracers such as FDG in cell lines and cultured primary cells. The capacity of the platform to perform multiplexed measurements was demonstrated by measuring differential FDG uptake in single cells subjected to different incubation conditions and expressing different types of glucose transporters. This method opens many new avenues of research in basic cell biology and human disease by capturing the full range of stochastic variations in highly heterogeneous cell populations in a repeatable and high-throughput manner.
authors.affiliation: †Division of Medical Physics, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305, United States.
authors.forename: Silvan
authors.initials: S
authors.lastname: Türkcan
authors.affiliation: ‡Department of Chemistry and Biochemistry, Santa Clara University, Santa Clara, California 95053, United States.
authors.forename: Julia
authors.initials: J
authors.lastname: Nguyen
authors.affiliation: §Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University, Stanford, California 94305, United States.
authors.forename: Marta
authors.initials: M
authors.lastname: Vilalta
authors.affiliation: ∥Department of Radiology, Stanford University Medical Center, Stanford, California 94305, United States.
authors.forename: Bin
authors.initials: B
authors.lastname: Shen
authors.affiliation: ∥Department of Radiology, Stanford University Medical Center, Stanford, California 94305, United States.
authors.forename: Frederick T
authors.initials: FT
authors.lastname: Chin
authors.affiliation: †Division of Medical Physics, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305, United States.
authors.forename: Guillem
authors.initials: G
authors.lastname: Pratx
authors.affiliation: ‡Department of Chemistry and Biochemistry, Santa Clara University, Santa Clara, California 95053, United States.
authors.forename: Paul
authors.initials: P
authors.lastname: Abbyad
mesh_terms: D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D059010:Single-Cell Analysis / Q000379:methods*
chemical_list: D019788:Fluorodeoxyglucose F18