Potential of FTIR Spectroscopy Applied to Exosomes for Alzheimer's Disease Discrimination: A Pilot Study


Alzheimer's disease (AD) diagnosis is based on psychological and imaging tests but can also include monitoring cerebrospinal fluid (CSF) biomarkers. However, CSF based-neurochemical approaches are expensive and invasive, limiting their use to well-equipped settings. In contrast, blood-based biomarkers are minimally invasive, cost-effective, and a widely accessible alternative. Blood-derived exosomes have recently emerged as a reliable AD biomarker source, carrying disease-specific cargo. Fourier-transformed infrared (FTIR) spectroscopy meets the criteria for an ideal diagnostic methodology since it is rapid, easy to implement, and has high reproducibility. This metabolome-based technique is useful for diagnosing a broad range of diseases, although to our knowledge, no reports for FTIR spectroscopy applied to exosomes in AD exist. In this ground-breaking pilot study, FTIR spectra of serum and serum-derived exosomes from two independent cohorts were acquired and analyzed using multivariate analysis. The regional UA-cohort includes 9 individuals, clinically diagnosed with AD, mean age of 78.7 years old; and the UMG-cohort comprises 12 individuals, clinically diagnosed with AD (based on molecular and/or imaging data), mean age of 73.2 years old. Unsupervised principal component analysis of FTIR spectra of serum-derived exosomes revealed higher discriminatory value for AD cases when compared to serum as a whole. Consistently, the partial least-squares analysis revealed that serum-derived exosomes present higher correlations than serum. In addition, the second derivative peak area calculation also revealed significant differences among Controls and AD cases. The results obtained suggest that this methodology can discriminate cases from Controls and thus be potential useful to assist in AD clinical diagnosis.



subject category

Neurosciences & Neurology


Martins, TS; Magalhaes, S; Rosa, IM; Vogelgsang, J; Wiltfang, J; Delgadillo, I; Catita, J; Silva, OABDE; Nunes, A; Henriques, AG

our authors


This work was funded by PTDC/DTPPIC/5587/2014 and POCI-01-0145-FEDER-016904 and also supported by Instituto de Biomedicina (iBiMED) - UIDB/04501/2020, the Fundacao para a Ciencia e Tecnologia (FCT) of the Ministerio da Educacao e Ciencia, COMPETE program, the QREN and the European Union (Fundo Europeu de Desenvolvimento Regional) and by the Integrated Programme of SR&TD pAGE (CENTRO 2020 - CENTRO-01-0145-FEDER-000003), co-funded by Centro 2020 program, Portugal 2020, European Union, through the European Regional Development Fund. JV was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - project number 413501650. The funding body had no influence in the design of the study and collection, analysis, and interpretation of data and in writing the manuscript. AGH is supported by the FCT stimulus of scientific employment, individual support (CEECIND/01803/2017). TSM was supported by the University of Aveiro through the individual PhD grant BD/REIT/7964/2019. JW is supported by an Ilidio Pinho professorship at University of Aveiro. We thank Hermann Esselmann for manuscript proofreading and suggestions.

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