Fluorescence detection of amyloid deposits in human tissues using histochemical dyes

About authors

1 Institute of Experimental Medicine, Saint Petersburg, Russia

2 Saint Petersburg State University, St Petersburg, Russia

Correspondence should be addressed: Valeria V. Guselnikova
Acad. Pavlov, 12, Saint Petersburg, 197376; ur.xednay@aiirelaV.avocinlesuG

About paper

Author contribution: Guselnikova VV — literature analysis, study planning, staining specimens, analysis and interpretation of the results, manuscript draft writing; Sufieva DA — quantitative data analysis; Tsyba DL — quantitative data analysis; Korzhevskii DE — conceptual development, study planning, manuscript editing.

Compliance with ethical standards: the study was conducted in accordance with the requirements of the World Medical Association Declaration of Helsinki (2013) and approved by the Ethics Committee of the Institute of Experimental Medicine (protocol № 3/18 dated November 22, 2018).

Received: 2021-07-12 Accepted: 2021-07-25 Published online: 2021-07-31

Recently, fluorescence microscopy becomes more available, presenting new opportunities to face several challenges of experimental biology and medicine. The study was aimed to assess the effectiveness of fluorescence microscopy for the identification of amyloid deposits in human tissues. Post-mortem samples of the myocardium (n = 12) and cerebral cortex (n = 8) obtained from subjects of both sexes aged 60–98 with verified amyloidosis were used as a material for the study. The specimens were stained using 11 different histochemical dyes and subsequently analyzed by light and fluorescence microscopy. Qualitative and quantitative analysis has shown that Thioflavin T is the most effective stain for fluorescence detection of β- and transthyretin amyloid in human tissues. Congo red staining is highly effective for the detection of transthyretin amyloidosis, however, it is ill-suited for the identification of β-amyloid plaques. It has been found that the ability of Congo red to exhibit fluorescence when binding to amyloid fibrils can be used for verification of amyloid deposits instead of the traditional polarized light microscopy. As has been first noted, methyl violet can selectively bind to β-amyloid with fluorescent complex formation. In addition, methyl violet treatment effectively reduces the autofluorescent background in the nervous tissue. This makes methyl violet staining a promising diagnostic tool for Alzheimer's-type pathology.

Keywords: fluorescence microscopy, amyloid, amyloid plaques, histochemistry, congo red, thioflavin, methyl violet