Uptake of small extracellular vesicles by recipient cells is facilitated by paracrine adhesion signaling
It’s firmly established that EVs play a major role in cell-cell communication, yet how EVs deliver their message to recipient cells is still not fully understood. In a critical breakthrough, Koichiro Hirosawa and colleagues have become the first group to see it happen, using cutting-edge microscopy and single particle imaging1. They report that cellular uptake of small EVs (sEVs) occurs through endocytosis, rather than membrane fusion. sEV binding to recipient cells induces intracellular calcium signalling that ultimately leads to internalisation. Intriguingly the effect was not observed when sEVs bound to the cells that produced them, only when they bound to different cells, termed ‘paracrine adhesion’ by the authors. This study used TRPS to characterise sEVs from cell culture supernatant, finding good agreement between diameters measured by transmission electron microscopy (TEM) and TRPS.
Helminth extracellular vesicles co‐opt host monocytes to drive T cell anergy
Parasitic roundworms cause chronic infections affecting millions of people worldwide. Borup et al. investigated how helminth worms use EVs to modulate their host’s immune response. They found that labelled EVs were preferentially taken up by monocytes but not T- or B-cells, and that EV-treated monocytes in turn decreased T-cell activation2. This suppression of T-cell response is part of the parasite’s survival strategy. While it’s bad news for the host during parasite infection, the authors point out that it could be a new avenue for research into treatments for inflammatory conditions such as colitis. Borup et al. isolated helminth EVs from concentrated culture medium with qEVoriginal/70 nm columns, using fractions 7-10 as EV-rich and fractions 16-25 as EV-depleted controls.
Enhanced packaging of U6 small nuclear RNA and splicing-related proteins into extracellular vesicles during HIV infection
Splicing is a key process in the HIV lifecycle and disruption of host gene splicing is known to occur during HIV infection. This paper from Yiyao Huang and colleagues completes one piece of the puzzle of how it happens. U6 snRNA is part of the spliceosome, playing a critical role in correct splicing of mRNA. This study reports that during acute infection, U6 snRNA appears to shift into EVs, lowering the amount in the nucleus and likely altering splicing and hence gene expression in infected cells3. What effect U6 snRNA loaded EVs then have on recipient cells is still a mystery and the authors highlight the need for further research on this fascinating topic. The study used qEV10/70 nm columns automated on an Automatic Fraction Collector (AFC) to isolate EVs from cell culture medium before downstream characterisation.
Therapeutic effects of platelet-derived extracellular vesicles on viral myocarditis correlate with biomolecular content
EVs are a heterogeneous bunch, with different types, contents and functions. Understanding this variation and its impact on recipient cells is fundamental to being able to use EVs therapeutically. In this paper, Danielle Beetler and fellow authors tackled one source of variability – EV donor characteristics. They hypothesised that platelet-derived EVs (PEVs) from healthy pre-menopausal females might have a stronger anti-inflammatory effect than PEVs from males and females of any age. While this hypothesis was not proved, both types of EV showed an anti-inflammatory effect in a mouse model of myocarditis, with miRNAs the likely mediators of this effect4. The authors carried out rigorous EV characterisation, using an Exoid to measure zeta potential and qEVoriginal/70 nm columns to isolate PEVs for imaging.
Incorporating Span 80 surfactant into lipid nanocapsules improves their biocompatibility and cellular uptake in B16F10 melanoma cells
Drug delivery is being transformed by lipid-based nanoparticles but there is still a lot to learn about how different formulations affect biopharmaceutical properties. Wu et al. found that adding Span 80, a hydrophobic surfactant, to lipid nanocapsules decreased cytotoxicity and increased cellular uptake in a murine melanoma, but not colorectal carcinoma, cell line5. The team were particularly interested in whether these changes could be due to the protein corona that forms around nanoparticles in a biological medium and showed that LNCs formulated with Span80 showed substantial changes in size and size distribution after incubation with conditioned culture medium. qEV columns were used to isolate LNC-protein complexes from free proteins after incubation in conditioned culture medium.
