A Novel Strategy to Increase the Yield of Exosomes (Extracellular Vesicles) for an Expansion of Basic Research

Abstract

Exosomes are tiny extracellular vesicles that are usually harvested in small quantities. Such small yield has been an obstacle for the expansion of the basic research regarding exosome analysis and applications in drug delivery. To increase exosome yield, we attempted to stimulate tumor cells via the addition of liposomes in vitro. Neutral, cationic-bare or PEGylated liposomes were incubated with four different tumor cell lines. The stimulatory effect of liposomal formulations on exosome secretion and cellular uptake propensity of the collected exosome by mother cells or different cells was evaluated. Both neutral and cationic-bare liposomes enhanced exosome secretion in a dose-dependent manner. Fluid cationic liposomes provided the strongest stimulation. Surprisingly, the PEGylation of bare liposomes diminished exosome secretion. Exosomes harvested in the presence of fluid cationic liposomes showed increased cellular uptake, but solid cationic liposomes did not. Our findings indicate that the physicochemical properties of liposomes determine whether they will act as a stimulant or as a depressant on exosome secretion from tumor cells. Liposomal stimulation may be a useful strategy to increase exosome yield, although further preparation to increase the purity of exosomes may be needed. In addition, fine-tuning of the biological properties of induced exosomes could be achieved via controlling the physicochemical properties of the stimulant liposomes.

Engineering of Exosomes to Target Cancer Metastasis

“…70 Liposomes formed the basis of a study involving exosome delivery of proteins to cancer cells, where they were co-incubated with a murine melanoma cell line (B16BL6). 27,28 The liposomes used for co-incubation were either fluid DOPE-based (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine) or solid HSPC-based (hydrogenated soy phosphatidylcholine). Exosomes were collected and isolated from the culture media, their protein contents analyzed and broken up into categories (tetraspanins, heat shock proteins, enzymes and others).…”

Exosomes and cancer: From oncogenic roles to therapeutic applications

“…PEGylation of exosome increases their biostability and circulation time. However, according to vascular leakiness of each tumor, the size of the nanodrug delivery vehicle must be customized …”

“…However, according to vascular leakiness of each tumor, the size of the nanodrug delivery vehicle must be customized. 242 The bioengineering and manipulation capacity of exosomes is an interesting and suitable property for cancer therapy proposal. Several reports have confirmed the feasibility of bioengineered exosomes for specific tissue or cell targeting and drug delivery.…”

Characteristics and roles of extracellular vesicles released by epidermal keratinocytes

“…Under serum‐free conditions with or without defined supplements, mammalian cells undergo severe stress that is communicated to adjacent cells by secreted EVs . An alternative approach to avoid stressing cells during EV studies is to deplete serum EVs by centrifugation that has also been described as media for EV secretion . Unsurprisingly, almost any stimuli, exogenous factor, or event that causes cellular stress results in increased export of EVs.…”

“…21,22 An alternative approach to avoid stressing cells during EV studies is to deplete serum EVs by centrifugation that has also been described as media for EV secretion. 15,23 Unsurprisingly, almost any stimuli, exogenous factor, or event that causes cellular stress results in increased export of EVs. In addition to serum-free and EVdepleted serum medium, other stimuli known to induce keratinocytes to release EVs include irradiation, 18 poly (I:C) which is an immunostimulant and present in some viruses, 15 TGFa 1 and hypoxia.…”