Imaging mass spectrometry demonstrates age-related decline in human adipose plasticity
Christelle Guillermier, … , Claude P. Lechene, Matthew L. Steinhauser
Christelle Guillermier, … , Claude P. Lechene, Matthew L. Steinhauser
Published March 9, 2017
Citation Information: JCI Insight. 2017;2(5):e90349. https://doi.org/10.1172/jci.insight.90349.
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Resource and Technical Advance Aging Endocrinology

Imaging mass spectrometry demonstrates age-related decline in human adipose plasticity

Abstract

Quantification of stable isotope tracers has revealed the dynamic state of living tissues. A new form of imaging mass spectrometry quantifies isotope ratios in domains much smaller than a cubic micron, enabling measurement of cell turnover and metabolism with stable isotope tracers at the single-cell level with a methodology we refer to as multi-isotope imaging mass spectrometry. In a first-in-human study, we utilize stable isotope tracers of DNA synthesis and de novo lipogenesis to prospectively measure cell birth and adipocyte lipid turnover. In a study of healthy adults, we elucidate an age-dependent decline in new adipocyte generation and adipocyte lipid turnover. A linear regression model suggests that the aging effect could be mediated by a decline in insulin-like growth factor-1 (IGF-1). This study therefore establishes a method for measurement of cell turnover and metabolism in humans with subcellular resolution while implicating the growth hormone/IGF-1 axis in adipose tissue aging.

Authors

Christelle Guillermier, Pouneh K. Fazeli, Soomin Kim, Mingyue Lun, Jonah P. Zuflacht, Jessica Milian, Hang Lee, Hugues Francois-Saint-Cyr, Francois Horreard, David Larson, Evan D. Rosen, Richard T. Lee, Claude P. Lechene, Matthew L. Steinhauser

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Figure 1

Measurement of human cell birth with MIMS.

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Measurement of human cell birth with MIMS. (A) 15N-thymidine–labeled leu...
(A) 15N-thymidine–labeled leukocytes, collected after a 2-day intravenous labeling period or subsequent 4-week label-free chase. Quantitative mass images reveal subcellular details. High phosphate content in nucleic acid accounts for high signal in nuclei of 31P images. 32S images demonstrate intense signal in the granules contained in granulocytes. 15N/14N hue saturation intensity image shows label localized to the nuclei of cells born during label administration (arrows). The rainbow scale ranges from blue, set to natural ratio (0.37%, expressed as 0% above natural ratio), to red, where the ratio is above the natural ratio (200% = 3 times natural ratio). Scale bar: 5 μm. (B) Frequency of labeled leukocyte subsets after pulse or chase (n = 6 subjects). Data displayed as Tukey box-and-whisker plots. Mann-Whitney tests were used to assess significance. Note, the y axis ranges from 0%–20%. (C) Labeling schematic for protocol 2, in which subjects were administered intravenous 15N-thymidine continuously for 3 days concurrently with oral 2H-water. The expected effective labeling period for 2H-water is prolonged relative to 15N-thymidine due to a total body water half-life of ~1 week. (D) 15N-thymidine/2H-water doubly labeled cells (arrows). Scale bar: 5 μm. (E) Colocalization of label in D confirmed quantitatively by plotting pixel values, which demonstrate associations among 15N, 2H, and 31P signals, consistent with DNA labeling. Each plotted data point is extracted from a single pixel on the quantitative mass or ratio images. (F) Pixel analysis from 15N-thymidine–unlabeled cells in D demonstrates no positive correlation between the 2H and 31P signals. (G) Data from representative subject undergoing double-labeling protocol (n = 3). After pulse (left), 15N-thymidine–labeled monocytes demonstrate high 2H-water labeling relative to 15N-unlabeled cells. After chase (right), high 2H-labeling in 15N-thymidine–labeled lymphocytes relative to that observed in 15N-unlabeled cells. Rare 15N– outliers that are highly 2H-labeled likely represent cells born after cessation of 15N-thymidine labeling but within the effective 2H-water–labeling period shown schematically in C. Data displayed as Tukey box-and-whisker plots. Mann-Whitney tests were used to assess significance. b.g., background.