Intratumoral heterogeneity, which is manifested in almost all of the hallmarks of cancer, including the significantly altered metabolic profiles of cancer cells, represents a challenge to effective cancer therapy. High-throughput measurements of the metabolism of individual cancer cells would allow direct visualization and quantification of intratumoral metabolic heterogeneity, yet the throughputs of current measurement techniques are limited to about 120 cells per hour. Here, we show that single-cell photoacoustic microscopy can reach throughputs of approximately 12,000 cells per hour by trapping single cells with blood in an oxygen-diffusion-limited high-density microwell array and by using photoacoustic imaging to measure the haemoglobin oxygen change (that is, the oxygen consumption rate) in the microwells. We demonstrate the capability of this label-free technique by performing high-throughput single-cell oxygen-consumption-rate measurements of cultured cells and by imaging intratumoral metabolic heterogeneity in specimens from patients with breast cancer. High-throughput single-cell photoacoustic microscopy of oxygen consumption rates should enable the faster characterization of intratumoral metabolic heterogeneity.
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The authors appreciate the help received from J. Yao in the initial phase of the project and J. Liang in the data analysis while they were former members of our laboratory. We also thank J. Ballard for his close reading of the manuscript. This work was sponsored by National Science Foundation (grant nos 1255930 and 1255921) and National Institutes of Health (grant nos DP1 EB016986 (NIH Director’s Pioneer Award) and R01 CA186567 (NIH Director’s Transformative Research Award)).
L.V.W. has a financial interest in Microphotoacoustics, Inc.; CalPACT, LLC and Union Photoacoustic Technologies, Ltd. These companies did not support this work.
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MitoRACE: evaluating mitochondrial function in vivo and in single cells with subcellular resolution using multiphoton NADH autofluorescence
The Journal of Physiology (2019)
Nature Biomedical Engineering (2019)