Membrane proteins significantly restrict exosome mobility

Abstract

Exosomes are membrane nanovesicles implicated in cell-to-cell signaling in which they transfer their molecular cargo from the parent to the recipient cells. This role essentially depends on the exosomes' small size, which is the prerequisite for their rapid migration through the crowded extracellular matrix and into and out of circulation. Here we report much lower exosome mobility than expected from the size of their vesicles, implicate membrane proteins in a substantially impeded rate of migration, and suggest an approach to quantifying the impact. The broadly distributed excess hydrodynamic resistance provided by surface proteins produces a highly heterogeneous and microenvironment-dependent hindrance to exosome mobility. The implications of the findings on exosome-mediated signaling are discussed.

Extracellular vesicle measurements with nanoparticle tracking analysis – An accuracy and repeatability comparison between NanoSight NS300 and ZetaView

“…However, size measurements by both NTA devices in general produced peaks at substantially higher sizes and broader size distributions as compared to TEM imaging as well as to SP‐IRIS. This discrepancy might at least in part result from the physical principle of size determination of the NTA devices, which is calculated based on the motion of particles in solution and influenced by the surface protein composition of EVs [27]. In line, measurements of liposomes, which are devoid of protein decorations, produced the lowest size peak using NanoSight NS300 followed by TEM imaging and ZetaView measurements.…”

“…Of note, both NTA devices could not reproduce TEM‐derived size distributions with peak diameter below 50 nm pointing out limitations of NTA. Differences might depend on the detection limit of NTA for smaller EVs and on the impact of protein surface cargo of EVs on their motility falsifying NTA‐derived size distributions [27].…”

“…The concentration measurement may depend on various parameters including size and device‐dependent detection limits. Important for this consideration is the EV surface protein cargo, which can attenuate EV motility in solution [27]. Thus, the protein surface cargo falsifies the diameter measured by NTA resulting in a broader and phase‐shifted size distribution of EVs.…”

Extracellular vesicles from human plasma and serum are carriers of extravesicular cargo—Implications for biomarker discovery

“…As the enzymatic removal of the EV surface proteins has been shown to hamper cellular uptake [49,50], the protein corona may affect the functional properties of EVs. The heterogeneity of the protein corona was shown to affect the hydrodynamic range of EVs, as well as their mobility in solution and extracellular matrix [51].…”

Gene Editing by Extracellular Vesicles

“…Damage of EV membranes (by electroporation, freeze-thaw cycles, etc.) or degradation of EV surface markers (e.g., by protease digestion) alter EV accumulation in target organs may impair their ability to cross biological barriers [ 159 , 160 , 161 ]. For example, protease digestion of EV surface proteins reduced their accumulation in the lungs [ 162 ].…”