Summary: Using Raman imaging technology, University of Twente researchers have been able to obtain clear images of brain tissue affected by Alzheimer’s disease.
Source: University of Twente.
Using ‘Raman’ optical technology, scientists of the University of Twente, can now produce images of brain tissue that is affected by Alzheimer’s disease. The images also include the surrounding areas, already showing changes.
Alzheimer’s disease is associated with areas of high protein concentration in brain tissue: plaques and tangles. Raman imaging is now used to get sharp images of these affected areas. It is an attractive technique, because it shows more than the specific proteins involved. The presence of water and lipids, influenced by protein presence, can also be detected. Using this technique, the researchers have studied brain tissue of four brain donors, three of them with Alzheimer’s disease.
The affected area can, in this way, be shown in a sharp and clear way. After image processing, even an area appears that is in transition between healthy and affected tissue: this may give an indication how the disease is spreading in the brain. Even in the brain tissue of the healthy person, a small area is detected with protein activity. This can be a first sign of a neurodegenerative disease.
Raman microscopy uses a laser beam for the detection of chemical substances. The energy of the reflected and scattered light gives an indication of the substances present in a sample. In each of the four brain samples, 4096 spectra were examined in this way. A major advantage of Raman is that the chemicals don’t need a pretreatment, it is ‘label free’. In chemical analysis, Raman has proven to be a powerful technique.
SMALLER THAN A CELL
In this case, Raman was used to examine brain tissue outside the body, but it could even be used ‘in vivo’ for detecting specific areas during surgery. Compared to MRI, PET and CT imaging, Raman is able to detect areas, smaller than cells, with very high precision. In this way, it can be a very valuable extra technique. The Raman images now show protein activity at neural cell level, but the sensitivity is high enough for detecting areas that are even smaller – as is the case with the brain sample of the healthy person.
Cees Otto, of the Medical Cell Biophysics group of UT, published his work in Scientific Reports, together with colleagues from Leiden University and from Spain and Austria.
Source: Wiebe Van Der Veen – University of Twente
Publisher: Organized by NeuroscienceNews.com.
Image Source: NeuroscienceNews.com image is credited to the researchers.
Original Research: Full open access research for “Hyperspectral Raman imaging of neuritic plaques and neurofibrillary tangles in brain tissue from Alzheimer’s disease patients” by Ralph Michael, Aufried Lenferink, Gijs F. J. M. Vrensen, Ellen Gelpi, Rafael I. Barraquer & Cees Otto in Scientific Reports. Published online November 15 2017 doi:10.1038/s41598-017-16002-3
Hyperspectral Raman imaging of neuritic plaques and neurofibrillary tangles in brain tissue from Alzheimer’s disease patients
Neuritic plaques and neurofibrillary tangles are crucial morphological criteria for the definite diagnosis of Alzheimer’s disease. We evaluated 12 unstained frontal cortex and hippocampus samples from 3 brain donors with Alzheimer’s disease and 1 control with hyperspectral Raman microscopy on samples of 30 × 30 µm. Data matrices of 64 × 64 pixels were used to quantify different tissue components including proteins, lipids, water and beta-sheets for imaging at 0.47 µm spatial resolution. Hierarchical cluster analysis was performed to visualize regions with high Raman spectral similarities. The Raman images of proteins, lipids, water and beta-sheets matched with classical brain morphology. Protein content was 2.0 times, the beta-sheet content 5.6 times and Raman broad-band autofluorescence was 2.4 times higher inside the plaques and tangles than in the surrounding tissue. The lipid content was practically equal inside and outside. Broad-band autofluorescence showed some correlation with protein content and a better correlation with beta-sheet content. Hyperspectral Raman imaging combined with hierarchical cluster analysis allows for the identification of neuritic plaques and neurofibrillary tangles in unstained, label-free slices of human Alzheimer’s disease brain tissue. It permits simultaneous quantification and distinction of several tissue components such as proteins, lipids, water and beta-sheets.
“Hyperspectral Raman imaging of neuritic plaques and neurofibrillary tangles in brain tissue from Alzheimer’s disease patients” by Ralph Michael, Aufried Lenferink, Gijs F. J. M. Vrensen, Ellen Gelpi, Rafael I. Barraquer & Cees Otto in Scientific Reports. Published online November 15 2017 doi:10.1038/s41598-017-16002-3