COMPARISON OF POLAR METABOLIC PROFILES BETWEEN PLASMA, SERUM, AND PLASMA/SERUM-DERIVED EXTRACELLULAR VESICLES

Polar metabolites and neurotransmitters in serum and plasma show significant alterations across psychiatric disorders, which makes them promising potential biomarkers. Lately, these molecules have also been analyzed in extracellular vesicles (EVs) from these biofluids. While metabolic profiles in plasma, serum, and EVs have all been explored, few studies have provided direct comparisons between these sample types. However, this comparison is crucial to understand the mechanisms of transport of these molecules in blood, as well as to determine the sample type best suited for specific analyses.
Our focus here was on targeted metabolomic profiling of different blood-derived sample types, namely serum, plasma, and EVs isolated from both plasma and serum. We used liquid chromatography-tandem mass spectrometry to analyze the levels of a range of polar metabolites.
Our analysis revealed marked differences between the sample types. Specifically, homovanillic acid, serotonin, 5-hydroxyindoleacetic acid, and acetylcholine were detected only in plasma and serum, while their levels in EV samples were below the limit of detection. Other metabolites were detected in both plasma/serum and EVs, namely: tyrosine, tryptophan, kynurenine, aspartate, glutamine, glutamate, γ-aminobutyric acid, glycine, spermidine, and spermine.
These results show that the polar metabolite content is significantly different in distinct blood-derived samples and provide a foundation for further studies of these metabolites in biofluids and extracellular vesicles.
This work has been funded by a grant from the Programme Johannes Amos Comenius under the Ministry of Education, Youth and Sports of the Czech Republic CZ.02.01.01/00/23_020/0008560.