Abstract
Extracellular vesicles (exosomes, EVs) (30-200 nm) that encapsulate biofunctional molecules (e.g., microRNAs and enzymes) are highly expected to be useful as next-generation therapeutic carriers because of their pharmaceutical advantages such as controlled immunogenicity, effective usage of cell-to-cell communication routes, absence of cytotoxicity, constitutive secretion, encapsulation of additional biofunctional molecules, and expression of functional proteins in membranes. However, methods for increasing the cellular uptake efficacy of EVs must be developed to achieve effective intracellular delivery of EV contents. In this review, I introduce and discuss novel techniques to enhance cellular EV uptake by modification of arginine-rich peptides on EV membranes for macropinocytosis induction and effective cellular uptake. Our research group previously found that macropinocytosis (accompanied by actin reorganization, ruffling of the plasma membrane, and engulfment of large volumes of extracellular fluid) is very important route for the cellular uptake of EVs. Therefore, we developed macropinocytosis induction techniques by modification of biofunctional peptides on EV membranes to enhance their cellular uptake. Arginine-rich cell-penetrating peptides have been shown to induce macropinocytosis via proteoglycans on plasma membranes, and we developed arginine-rich cell-penetrating peptide-modified EVs that can actively induce macropinocytotic uptake by cells. In addition, I discuss effects of lyophilization of arginine-rich cell-penetrating peptide-modified EVs on their biological activity. Our findings may contribute to the development of EV-based intracellular delivery systems via macropinocytosis.
