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Anal Chem. 2015 Jul 7;87(13):6667-73. doi: 10.1021/acs.analchem.5b00792. Epub 2015 Jun 15.

Single-Cell Analysis of [18F]Fluorodeoxyglucose Uptake by Droplet Radiofluidics.

Author information

1
†Division of Medical Physics, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305, United States.
2
‡Department of Chemistry and Biochemistry, Santa Clara University, Santa Clara, California 95053, United States.
3
§Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University, Stanford, California 94305, United States.
4
∥Department of Radiology, Stanford University Medical Center, Stanford, California 94305, United States.

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.

PMID:
26035453
PMCID:
PMC4669076
DOI:
10.1021/acs.analchem.5b00792
[Indexed for MEDLINE]
Free PMC Article

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