Quantification of Lipid Metabolism in Living Cells through the Dynamics of Lipid Droplets Measured by Stimulated Raman Scattering Imaging

Dysregulation of lipid metabolism is associated with many diseases including cancer. Lipid droplet (LD), a ubiquitous organelle in mammalian cells, serves as a hub for lipid metabolism. Conventional assays on the measurement of lipid metabolism rely on the quantification of the lipid composition or...

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Bibliographic Details
Published in:Analytical chemistry (Washington) 2017-04, Vol.89 (8), p.4502-4507
Main Authors: Zhang, Chi, Li, Junjie, Lan, Lu, Cheng, Ji-Xin
Format: Article
Language:English
Subjects:
Cancer
Cells
Cells (biology)
Diseases
Droplets
Dynamics
Glucose
Lipid metabolism
Lipids
Mammals
Metabolism
Raman scattering
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Summary:Dysregulation of lipid metabolism is associated with many diseases including cancer. Lipid droplet (LD), a ubiquitous organelle in mammalian cells, serves as a hub for lipid metabolism. Conventional assays on the measurement of lipid metabolism rely on the quantification of the lipid composition or amount. Such methods cannot distinguish LDs having different biofunctionalities in living cells, and thus could be inaccurate in measuring the instantaneous lipogenesis of the living cells. We applied label-free stimulated Raman scattering microscopy to quantify the LDs’ spatial-temporal dynamics, which showed direct links to cellular lipid metabolisms and can separate LDs involved in different metabolic events. In human cancer cells, we found that changes in the maximum displacement of LDs reflected variations in cellular lipogenic activity, and changes in the average speed of LDs revealed alterations in LD size. The LD dynamics analysis allowed for more accurate measurement in the lipogenesis and LD dimensions, and can break the optical diffraction limit to detect small variation in lipid metabolism that was conventionally undetectable. By this method, we revealed changes in the lipogenic activity and LD sizes during glucose starvation of HeLa cells and transforming growth factor beta-induced epithelial-to-mesenchymal transition of SKOV-3 cells. This method opens a way to quantify lipid metabolism in living cells during cellular development and transition.
ISSN:0003-2700
1520-6882
DOI:10.1021/acs.analchem.6b04699