Quantitative intrinsic auto-cathodoluminescence can resolve spectral signatures of tissue-isolated collagen extracellular matrix

• Published in: Communications biology Vol. 2; no. 1; p. 69
• Main Authors: Zielinski, Marcin S., Vardar, Elif, Vythilingam, Ganesh, Engelhardt, Eva-Maria, Hubbell, Jeffrey A., Frey, Peter, Larsson, Hans M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 18.02.2019; Nature Publishing Group
• Subjects: 13/107; 14/28; 14/5; 631/1647/328/1649; 631/61/54/994; 82/58; Animals; Biology; Biomedical and Life Sciences; Cattle; Cells, Cultured; Collagen; Collagen - metabolism; Collagen - ultrastructure; Electric Conductivity; Electrical conductivity; Extracellular matrix; Extracellular Matrix - metabolism; Extracellular Matrix - ultrastructure; Fibrin; Humans; Life Sciences; Localization; Luminescent Measurements - methods; Mass Spectrometry - methods; Mass spectroscopy; Microscopy, Electron, Scanning; Rats; Scanning electron microscopy; Smooth muscle; Spatial discrimination; Spectrum analysis
• ISSN: 2399-3642; 2399-3642
• DOI: 10.1038/s42003-019-0313-x

By analyzing isolated collagen gel samples, we demonstrated in situ detection of spectrally deconvoluted auto-cathodoluminescence signatures of specific molecular content with precise spatial localization over a maximum field of view of 300 µm. Correlation of the secondary electron and the hyperspectral images proved ~40 nm resolution in the optical channel, obtained due to a short carrier diffusion length, suppressed by fibril dimensions and poor electrical conductivity specific to their organic composition. By correlating spectrally analyzed auto-cathodoluminescence with mass spectroscopy data, we differentiated spectral signatures of two extracellular matrices, namely human fibrin complex and rat tail collagen isolate, and uncovered differences in protein distributions of isolated extracellular matrix networks of heterogeneous populations. Furthermore, we demonstrated that cathodoluminescence can monitor the progress of a human cell-mediated remodeling process, where human collagenous matrix was deposited within a rat collagenous matrix. The revealed change of the heterogeneous biological composition was confirmed by mass spectroscopy. Zielinski et al. show that quantitative label-free cathodoluminescence-scanning electron microscopy differentiates spectral signatures of two extracellular matrices. This method can monitor the progress of a smooth muscle cell-mediated remodeling process without using antibodies to enhance the optical signal.