Physicochemical Characterization of Liposomes That Mimic the Lipid Composition of Exosomes for Effective Intracellular Trafficking

Abstract

Exosomes mediate communication between cells in the body by the incorporation and transfer of biological materials. To design an artificial liposome, which would mimic the lipid composition and physicochemical characteristics of naturally occurring exosomes, we first studied the physicochemical properties of exosomes secreted from HepG2 cells. The exosome stiffness obtained by atomic force microscopy was moderate. Some liposomes were then fabricated to mimic the representative reported lipid composition of exosomes. Their physicochemical properties and cellular internalization efficiencies were investigated to optimize the cellular internalization efficiency of the liposomes. A favorable internalization efficiency was obtained by incubating HeLa cells with 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)/cholesterol (Chol)/1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS) (40/40/20 mol %) liposomes, which have a similar stiffness and zeta potential to exosomes. A dramatic increase in internalization efficiency was demonstrated by adding DOPS to simple DSPC/Chol liposomes. We found that DOPS had a more desirable effect on cellular internalization than its saturated lipid counterpart, 1,2-distearoyl-sn-glycero-3-phospho-l-serine. Furthermore, it was shown that the phosphatidylserine-binding protein, T-cell immunoglobulin mucin protein 4, was largely involved in the intracellular transfer of DSPC/Chol/DOPS liposomes. Thus, DOPS was a key lipid to provide the appropriate stiffness, zeta potential, and membrane surface affinity of the resulting liposome. Our results may help develop efficient drug carriers aiming to internalize active substances into cells.

Effect of Sample Concentration on Nanoparticle Tracking Analysis of Small Extracellular Vesicles and Liposomes Mimicking the Physicochemical Properties of Exosomes

“…Liposome Preparations Liposomes that mimicked the physical characteristics of exosomes were fabricated based on our previous report. 30) The lipid composition (mol%) of liposomes was DSPC/Chol/DOPS (40/40/20 mol%) and were prepared using a modified Bangham method. 33) Briefly, the desired amounts of lipids were mixed in chloroform and dried by evaporation at 70 °C to create a thin homogeneous lipid film.…”

“…Artificial beads have been used to examine factors that affect NTA, 25,26) and there are several reports that have addressed device-dependent and -independent sources of NTA measurement error and uncertainty. 22,25,[27][28][29][30] Most of these studies use polystyrene nanoparticles (PSN) as artificial beads. However, sEVs are complex soft lipid nanoparticles that are multimodal in size and the use of polystyrene nanoparticles as a model of sEV is not necessarily ideal.…”

“…We have recently developed liposomes that mimic the lipid composition and physical properties, e.g., size, zeta potential and membrane rigidity, of naturally occurring exosomes to clarify physicochemical factors that affect the cellular internalization of exosomes. 31) Therefore, in this study, we used liposomes as a model of exosomes to standardize NTA.…”

Techniques for increasing the yield of stem cell-derived exosomes: what factors may be involved?

“…However, clinical applications of liposomes are scarce due to their undesirable immunogenicity and unsatisfactory stability, biocompatibility, targeting ability, and absorbability (Antimisiaris et al, 2018;Guimarães et al, 2021). Such drawbacks can be largely overcome by fabricating an exosome-liposome complex, by which the advantages of two can complement each other (Haraszti et al, 2019;Sakai-Kato et al, 2020). In theory, artificial exosomes with their laden nucleic acid antigen can be employed to target dendritic cells by the self-assembly of microemulsion micelle.…”

Extracellular vesicles, lipids, and lipoproteins in early pregnant sheep

“…The biological effects elicited specifically by the lipid, protein, or nucleic acid cargo warrants further examination. The development of liposomes with more biologically relevant lipid makeups could be used to parse out the biological effects of EV lipids in early pregnancy events compared to some of the nucleic acid or protein cargo [479].…”