Raman spectroscopy as a quick tool to assess purity of extracellular vesicle preparations and predict their functionality

ABSTRACT

Extracellular vesicles (EVs) from a variety of stem cell sources are believed to harbour regenerative capacity, which may be exploited for therapeutic purposes. Because of EV interaction with other soluble secreted factors, EV activity may depend on the employed purification method, which limits cross-study comparisons and therapeutic development. Raman spectroscopy (RS) is a quick and easy method to assess EV purity and composition, giving in-depth biochemical overview on EV preparation. Hereby, we show how this method can be used to characterise EVs isolated from human liver stem cells and bone marrow mesenchymal stem/stromal cells by means of conventional ultracentrifugation (UC) and size exclusion chromatography (SEC) protocols. The obtained EV preparations were demonstrated to be characterised by different degrees of purity and a specific Raman fingerprint that represents both the cell source and the isolation procedure used. Moreover, RS provided useful hints to explore the factors underlying the functional diversity of EV preparations from the same cell source, thus representing a valuable tool to assess EV quality prior to functional assays or therapeutic application.

KEYWORDS:

• Extracellular vesicles
• stem cell
• Raman spectroscopy
• size exclusion chromatography
• ultracentrifugation
• regenerative medicine

Disclosure statement

No potential conflict of interest was reported by the authors.

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Additional information

Funding

This work was supported by the Italian Ministry of Health [Ricerca Corrente to IRCCS Fondazione Don Carlo Gnocchi and IRCCS Istituto Ortopedico Galeazzi] and by the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme FP7/2007-2013/ [REA grant agreement n° 612224: EVEStemInjury].