Real-time Raman and SRS imaging of living human macrophages reveals cell-to-cell heterogeneity and dynamics of lipid uptake.
Monitoring living cells in real-time is important in order to unravel complex dynamic processes in life sciences. In particular the dynamics of initiation and progression of degenerative diseases is intensely studied. In atherosclerosis the thickening of arterial walls is related to high lipid levels in the blood stream, which trigger the lipid uptake and formation of droplets as neutral lipid reservoirs in macrophages in the arterial wall. Unregulated lipid uptake finally results in foam cell formation, which is a hallmark of atherosclerosis. In previous studies, the uptake and storage of different fatty acids was monitored by measuring fixed cells. Commonly employed fluorescence staining protocols are often error prone because of cytotoxicity and unspecific fluorescence backgrounds. By following living cells with Raman spectroscopic imaging, lipid uptake of macrophages was studied with real-time data acquisition. Isotopic labeling using deuterated palmitic acid has been combined with spontaneous and stimulated Raman imaging to investigate the dynamic process of fatty acid storage in human macrophages for incubation times from 45 min to 37 h. Striking heterogeneity in the uptake rate and the total concentration of deuterated palmitic acid covering two orders of magnitude is detected in single as well as ensembles of cultured human macrophages. SRS signal of deuterated palmitic acid measured at the CD vibration band after incorporation into living macrophages.
Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Straße 9, 07745, Jena, Germany.|Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany.
Clara
C
Stiebing
Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Straße 9, 07745, Jena, Germany.|Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany.
Tobias
T
Meyer
APE Angewandte Physik & Elektronik GmbH, Plauener Straße 163-165, 13053, Berlin.
Ingo
I
Rimke
Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Straße 9, 07745, Jena, Germany.|Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany.
Christian
C
Matthäus
Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany.
Michael
M
Schmitt
Institute of Nutrition and Abbe Center of Photonics, Friedrich Schiller University Jena, Dornburger Straße 25, 07743, Jena, Germany.|Competence Cluster of Nutrition and Cardiovascular Health (nutriCARD), Halle-Jena-Leipzig, Friedrich Schiller University Jena, Dornburger Straße 25, 07743, Jena, Germany.
Stefan
S
Lorkowski
Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Straße 9, 07745, Jena, Germany.|Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany.
Jürgen
J
Popp
D050197:Atherosclerosis; D005227:Fatty Acids / Q000378:metabolism*; D006801:Humans; D050356:Lipid Metabolism; D008264:Macrophages / Q000378:metabolism*; D013059:Spectrum Analysis, Raman
D005227:Fatty Acids
Monocyte-derived macrophages; coherent Raman imaging; isotope labeling; lipid droplet; palmitic acid; stimulated Raman scattering