Raman Spectral Signatures of Serum-Derived Extracellular Vesicle-Enriched Isolates May Support the Diagnosis of CNS Tumors

Abstract

Investigating the molecular composition of small extracellular vesicles (sEVs) for tumor diagnostic purposes is becoming increasingly popular, especially for diseases for which diagnosis is challenging, such as central nervous system (CNS) malignancies. Thorough examination of the molecular content of sEVs by Raman spectroscopy is a promising but hitherto barely explored approach for these tumor types. We attempt to reveal the potential role of serum-derived sEVs in diagnosing CNS tumors through Raman spectroscopic analyses using a relevant number of clinical samples. A total of 138 serum samples were obtained from four patient groups (glioblastoma multiforme, non-small-cell lung cancer brain metastasis, meningioma and lumbar disc herniation as control). After isolation, characterization and Raman spectroscopic assessment of sEVs, the Principal Component Analysis–Support Vector Machine (PCA–SVM) algorithm was performed on the Raman spectra for pairwise classifications. Classification accuracy (CA), sensitivity, specificity and the Area Under the Curve (AUC) value derived from Receiver Operating Characteristic (ROC) analyses were used to evaluate the performance of classification. The groups compared were distinguishable with 82.9–92.5% CA, 80–95% sensitivity and 80–90% specificity. AUC scores in the range of 0.82–0.9 suggest excellent and outstanding classification performance. Our results support that Raman spectroscopic analysis of sEV-enriched isolates from serum is a promising method that could be further developed in order to be applicable in the diagnosis of CNS tumors.

Toward the nanoscale chemical and physical probing of milk-derived extracellular vesicles using Raman and tip-enhanced Raman spectroscopy

“…, to assess their purity or for diagnostic purposes. 10,35–43 While confocal Raman spectroscopy involves the global analysis of the mean properties of a large number of vesicles, TERS may enable the investigation of single EVs with high spatial resolution, e.g. , to identify domains and specific fingerprint areas to be used as biomarkers.…”

Proteome of human glioblastoma and meningioma tissue small extracellular vesicles

“…We previously reported a method to isolate small EVs from the extracellular matrix (ECM) of post-mortem human frontal cortex (13, 15, 18). The vesicles contain the hallmarks of endosomal derived exosomes (13, 15) and fulfilled the experimental requirements of the International Society for Extracellular Vesicles 2018 guidelines (19).…”

“…While there have been several studies on GBM derived EVs, only a few have been conducted on MNG derived EVs (7–9, 18, 50, 51). A study by Ricklefs et al (2022) observed that the levels of circulating EVs in the blood of meningioma patients are increased, correlating with malignancy grade and oedema, but subsequently declined post-surgery (8).…”

The role of the metabolite cargo of extracellular vesicles in tumor progression

“…In contrast, analysis of the whole EV molecular pattern of the whole EV set would provide more relevant results. This approach has recently been applied in clinical studies for tumor diagnostic purposes [142][143][144].…”