Single Particle Liquid Biopsy Analysis for Disease Diagnostics

Liquid biopsies from patients are a non-invasive and information rich medium for diagnostics. These biological fluids contain extracellular vesicles (EVs); nano-sized membrane vesicles with a phospholipid bilayer, released by most cells whether healthy or diseased. The lipid, protein and nucleic acid composition of EVs has been found specific to their cell-type origin and therefore it may be possible to trace EVs in biological fluids to their source. Studies by the Riley group have shown that EVs secreted from the epicardium play a critical role in the human heart's regenerative capacity in response to cardiac injury (Villa del Campo et al. 2021 Cardiovasc. Res.). Therefore, if we are able to characterise the contents of EVs in biological fluids, link them back to their cellular origin (e.g. injured heart tissue) and identify their specific regenerative potential, using EVs as biomarkers can offer a unique, non-invasive liquid-biopsy-based solution for diagnosis and longitudinal monitoring of tissue regeneration including treatment response.

A key challenge is the heterogeneity of the samples which contain EVs from multiple cell types. The Stevens group has developed a novel platform called SPARTA(registered trademark) (Single Particle Automated Raman Trapping Analysis), which is now being commercialised by spin-out company SPARTA Biodiscovery Ltd. This technique offers a unique solution for analyses of EVs by utilizing automated single particle trapping with Raman spectroscopy. This means SPARTA(registered trademark) can provide high-throughput biochemical information, in the form of Raman spectral fingerprints of individual EVs, enabling us to distinguish between EV subtypes within mixtures, which would not be possible with bulk techniques. Research in the Stevens group (Penders et al. 2021 ACS Nano) has indicated a tremendous potential for sensitive and specific detection of disease vs. healthy cell derived EVs using SPARTA(registered trademark).

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