Identification of amyloid-beta (Aβ) plaques in freshly frozen human brain tissue using Raman spectroscopy

Alzheimer's disease (AD) is the most common form of dementia, which is one of the main death leading causes with around 46 million people affected worldwide. Alzheimer's disease is characterized by the accumulation of extracellular deposits of proteins in the brain, known as amyloid-beta (Aβ) plaques. Currently, in-vivo detection of Aβ pathology is solely possible by two invasive techniques: the analysis of cerebral fluid or PET imaging. Raman spectroscopy may be an alternative way of in-vivo diagnosis of Aβ deposits as it is sensitive to concentrations of biomolecules. It is an established and common non-destructive technique, which in addition allows for minimal sample preparation. Recent publications on transgenic mouse and human AD brain tissue suggest that Raman spectroscopy is an adequate technique to identify and localize Aβ plaques1,2. However, publications on human tissue lack the proof of plaque existence at the same location, imaged with Raman spectroscopy. The present study is designed to confirm ultimately a match between Raman spectra and possible amyloid-beta plaque locations. This is achieved by superimposing the autofluorescence image, the Raman imaging map and the stained fluorescence image of the same tissue section. Additionally, obtained data will be compared to previous studies of post mortem human AD brain tissue that was formalin fixed and paraffin embedded.