scholarly journals Label-free characterization of Amyloid-β-plaques and associated lipids in brain tissues using stimulated Raman scattering microscopy

2019 ◽  
Author(s):  
Volker Schweikhard ◽  
Andrea Baral ◽  
Vishnu Krishnamachari ◽  
William C. Hay ◽  
Martin Fuhrmann
Keyword(s):  
Raman Scattering ◽  
Neurodegenerative Diseases ◽  
Membrane Lipids ◽  
Stimulated Raman Scattering ◽  
Three Dimensional ◽  
Brain Slices ◽  
Amyloid Β ◽  
Brain Structures ◽  
Label Free ◽  
Stimulated Raman

ABSTRACTThe brains of patients with neurodegenerative diseases such as Alzheimer’s Disease (AD) often exhibit pathological alterations that involve abnormal aggregations of proteins and lipids. Here, we demonstrate that high-resolution, label-free, chemically-specific imaging using Stimulated Raman Scattering Microscopy (SRS) provides novel insights into the biophysical properties and biochemical composition of such pathological structures. In brain slices of a mouse model of AD, SRS reveals large numbers of Amyloid-β plaques that commonly form a characteristic, three-dimensional core-shell structure, with a fibrillar proteinaceous core surrounded by a halo-like shell of lipid-rich deposits. SRS spectroscopic imaging allows for a clean, label-free visualization of the misfolded (β-sheet) Amyloid-β content in the plaque core. Surrounding lipid-rich deposits are found to contain comparatively high concentrations of membrane lipids (sphingomyelin, phosphatidylcholine), but lower levels of cholesterol than healthy white matter structures. Overall, the SRS spectra of plaque-associated lipids closely resemble those of nearby neurites, with the notable difference of a higher degree of lipid unsaturation compared to healthy brain structures. We hypothesize that plaque-associated lipid deposits may result from neuritic dystrophy associated with AD, and that the observed increased levels of unsaturation could help identify the kinds of pathological alterations taking place. Taken together, our results highlight the potential of Stimulated Raman Scattering microscopy to contribute to a deeper understanding of neurodegenerative diseases.

scholarly journals Volumetric chemical imaging by clearing-enhanced stimulated Raman scattering microscopy

2019 ◽  
Vol 116 (14) ◽  
pp. 6608-6617 ◽  
Author(s):  
Mian Wei ◽  
Lingyan Shi ◽  
Yihui Shen ◽  
Zhilun Zhao ◽  
Asja Guzman ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Optical Microscopy ◽  
Stimulated Raman Scattering ◽  
Three Dimensional ◽  
Lipid Synthesis ◽  
Chemical Imaging ◽  
Label Free ◽  
Tissue Clearing ◽  
Metabolic Activities ◽  
Stimulated Raman

Three-dimensional visualization of tissue structures using optical microscopy facilitates the understanding of biological functions. However, optical microscopy is limited in tissue penetration due to severe light scattering. Recently, a series of tissue-clearing techniques have emerged to allow significant depth-extension for fluorescence imaging. Inspired by these advances, we develop a volumetric chemical imaging technique that couples Raman-tailored tissue-clearing with stimulated Raman scattering (SRS) microscopy. Compared with the standard SRS, the clearing-enhanced SRS achieves greater than 10-times depth increase. Based on the extracted spatial distribution of proteins and lipids, our method reveals intricate 3D organizations of tumor spheroids, mouse brain tissues, and tumor xenografts. We further develop volumetric phasor analysis of multispectral SRS images for chemically specific clustering and segmentation in 3D. Moreover, going beyond the conventional label-free paradigm, we demonstrate metabolic volumetric chemical imaging, which allows us to simultaneously map out metabolic activities of protein and lipid synthesis in glioblastoma. Together, these results support volumetric chemical imaging as a valuable tool for elucidating comprehensive 3D structures, compositions, and functions in diverse biological contexts, complementing the prevailing volumetric fluorescence microscopy.

scholarly journals Label-free imaging of amyloid plaques in Alzheimer’s disease with stimulated Raman scattering microscopy

2018 ◽  
Vol 4 (11) ◽  
pp. eaat7715 ◽  
Author(s):  
Minbiao Ji ◽  
Michal Arbel ◽  
Lili Zhang ◽  
Christian W. Freudiger ◽  
Steven S. Hou ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Raman Scattering ◽  
Stimulated Raman Scattering ◽  
Imaging Modality ◽  
Amyloid Β ◽  
Amyloid Plaques ◽  
Label Free ◽  
Thin Sections ◽  
Stimulated Raman

One of the key pathological features of Alzheimer’s disease (AD) is the existence of extracellular deposition of amyloid plaques formed with misfolded amyloid-β (Aβ). The conformational change of proteins leads to enriched contents of β sheets, resulting in remarkable changes of vibrational spectra, especially the spectral shifts of the amide I mode. Here, we applied stimulated Raman scattering (SRS) microscopy to image amyloid plaques in the brain tissue of an AD mouse model. We have demonstrated the capability of SRS microscopy as a rapid, label-free imaging modality to differentiate misfolded from normal proteins based on the blue shift (~10 cm−1) of amide I SRS spectra. Furthermore, SRS imaging of Aβ plaques was verified by antibody staining of frozen thin sections and fluorescence imaging of fresh tissues. Our method may provide a new approach for studies of AD pathology, as well as other neurodegenerative diseases associated with protein misfolding.

scholarly journals Label-Free Biomedical Imaging with High Sensitivity by Stimulated Raman Scattering Microscopy

Science ◽  
2008 ◽  
Vol 322 (5909) ◽  
pp. 1857-1861 ◽  
Author(s):  
Christian W. Freudiger ◽  
Wei Min ◽  
Brian G. Saar ◽  
Sijia Lu ◽  
Gary R. Holtom ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Biomedical Imaging ◽  
Stimulated Raman Scattering ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Raman Microscopy ◽  
Label Free ◽  
Omega 3 ◽  
Low Sensitivity ◽  
Stimulated Raman

Label-free chemical contrast is highly desirable in biomedical imaging. Spontaneous Raman microscopy provides specific vibrational signatures of chemical bonds, but is often hindered by low sensitivity. Here we report a three-dimensional multiphoton vibrational imaging technique based on stimulated Raman scattering (SRS). The sensitivity of SRS imaging is significantly greater than that of spontaneous Raman microscopy, which is achieved by implementing high-frequency (megahertz) phase-sensitive detection. SRS microscopy has a major advantage over previous coherent Raman techniques in that it offers background-free and readily interpretable chemical contrast. We show a variety of biomedical applications, such as differentiating distributions of omega-3 fatty acids and saturated lipids in living cells, imaging of brain and skin tissues based on intrinsic lipid contrast, and monitoring drug delivery through the epidermis.

scholarly journals Utilizing Stimulated Raman Scattering Microscopy To Study Intracellular Distribution of Label-Free Ponatinib in Live Cells

2019 ◽  
Vol 63 (5) ◽  
pp. 2028-2034 ◽  
Author(s):  
Kristel Sepp ◽  
Martin Lee ◽  
Marie T. J. Bluntzer ◽  
G. Vignir Helgason ◽  
Alison N. Hulme ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Stimulated Raman Scattering ◽  
Intracellular Distribution ◽  
Live Cells ◽  
Label Free ◽  
Stimulated Raman

scholarly journals Label-free chemical imaging flow cytometry by high-speed multicolor stimulated Raman scattering

2019 ◽  
Vol 116 (32) ◽  
pp. 15842-15848 ◽  
Author(s):  
Yuta Suzuki ◽  
Koya Kobayashi ◽  
Yoshifumi Wakisaka ◽  
Dinghuan Deng ◽  
Shunji Tanaka ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Raman Scattering ◽  
Cancer Biology ◽  
High Speed ◽  
Stimulated Raman Scattering ◽  
Chemical Imaging ◽  
Fluorescent Labeling ◽  
Label Free ◽  
Imaging Flow Cytometry ◽  
Stimulated Raman

Combining the strength of flow cytometry with fluorescence imaging and digital image analysis, imaging flow cytometry is a powerful tool in diverse fields including cancer biology, immunology, drug discovery, microbiology, and metabolic engineering. It enables measurements and statistical analyses of chemical, structural, and morphological phenotypes of numerous living cells to provide systematic insights into biological processes. However, its utility is constrained by its requirement of fluorescent labeling for phenotyping. Here we present label-free chemical imaging flow cytometry to overcome the issue. It builds on a pulse pair-resolved wavelength-switchable Stokes laser for the fastest-to-date multicolor stimulated Raman scattering (SRS) microscopy of fast-flowing cells on a 3D acoustic focusing microfluidic chip, enabling an unprecedented throughput of up to ∼140 cells/s. To show its broad utility, we use the SRS imaging flow cytometry with the aid of deep learning to study the metabolic heterogeneity of microalgal cells and perform marker-free cancer detection in blood.

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