Calorimetry of extracellular vesicles fusion to single phospholipid membrane

Abstract

Extracellular vesicles (EVs)-mediated communication relies not only on the delivery of complex molecular cargoes as lipids, proteins, genetic material, and metabolites to their target cells but also on the modification of the cell surface local properties induced by the eventual fusion of EVs’ membranes with the cells’ plasma membrane. Here we applied scanning calorimetry to study the phase transition of single phospholipid (DMPC) monolamellar vesicles, investigating the thermodynamical effects caused by the fusion of doping amounts of mesenchymal stem cells-derived EVs. Specifically, we studied EVs-induced consequences on the lipids distributed in the differently curved membrane leaflets, having different density and order. The effect of EV components was found to be not homogeneous in the two leaflets, the inner (more disordered one) being mainly affected. Fusion resulted in phospholipid membrane flattening associated with lipid ordering, while the transition cooperativity, linked to membrane domains’ coexistence during the transition process, was decreased. Our results open new horizons for the investigation of the peculiar effects of EVs of different origins on target cell membrane properties and functionality.

Isolation, characterization, and fibroblast uptake of bacterial extracellular vesicles from Porphyromonas gingivalis strains

“…Le et al (2023) detected dark structures on TEM pictures of EV‐like particles (EVLPs) from BHI, but after using eukaryotic EV markers they concluded that the EVLPs in BHI probably are large protein aggregates and not true EVs. Finally, several other factors can affect the NTA results, among them the potential fusion of vesicles (Grava et al, 2022). Different selections of threshold and camera levels during NTA analysis will also affect the outcome (Shao et al, 2018).…”

Integrated Strategies for a Holistic View of Extracellular Vesicles

“…The lipid phase borders present on the artificial bilayers (raft-like structures) seem to act as preferential docking sites from where the different sEV components spread with different kinetics in the surrounding bilayer. Further insights on the fusion mechanism of such systems have been explored by the same groups by means of differential scanning calorimetry and dynamic light scattering, 26 and these experiments allowed them to observe after fusion of sEVs with artificial lipid vesicles (LUVs) an increased rigidity of the bilayer, a flattening of the membrane with an increase in size of the LUVs, a decrease in the lateral mobility of the lipids, and a decreased transition cooperativity, as a sign of an increased membrane parcellation. Such experiments are important not only because they shed light on the likelihood of EVs to interact with specific domains with respect to others but also because they allowed the investigation of the effects of EVs on target cell membranes, opening perspectives in this field that are applicable to EVs of different origin.…”