Radioiodination of extravesicular surface constituents to study the biocorona, cell trafficking and storage stability of extracellular vesicles.

Background: Extracellular vesicles (EVs) are produced by all cell types and serve as biological packets delivering a wide variety of molecules for cell-to-cell communication. However, the biology of the EV extravesicular surface domain that we have termed EV 'biocorona' remains underexplored. Upon cell secretion, EVs possess an innate biocorona containing membrane integral and peripheral constituents that is modified by acquired constituents post secretion. This distinguishes EVs from synthetic nanoparticulate biomaterials that are limited to an adsorption-based, acquired biocorona.

Methods: The EV biocorona molecular constituents were radiolabeled with I to study biocorona constituents and its surface dynamics. As example toolset applications, I-EVs were utilized to study EV cell trafficking and the stability of the EV biocorona during storage.

Results: The biocorona of EVs consisted of proteins, lipids, DNA and RNA. The cellular uptake of I-EVs was temperature dependent and internalized I-EVs were rapidly recycled by cells. When I-EVs were stored in a purified state, they exhibited time and temperature dependent biocorona shedding and proteolytic degradation that was partially inhibited in the presence of serum.

Conclusion: The EV biocorona is complex and dynamic. Radiolabeling of the EV biocorona enables a unique platform methodology to study the biocorona and will facilitate unlocking EV's full clinical translation potential.

General Significance: The EV biocorona affects EV mediated biological processes in health and disease. Acquiring knowledge of the EV biocorona composition, dynamics, stability and structure not only informs the diagnostic and therapeutic translation of EVs but also aids in designing biomimetic nanomaterials for drug delivery.