Extracellular Vesicles as New Players in Drug Delivery: A Focus on Red Blood Cells-Derived EVs

Abstract

The article is divided into several sections, focusing on extracellular vesicles’ (EVs) nature, features, commonly employed methodologies and strategies for their isolation/preparation, and their characterization/visualization. This work aims to give an overview of advances in EVs’ extensive nanomedical-drug delivery applications. Furthermore, considerations for EVs translation to clinical application are summarized here, before focusing the review on a special kind of extracellular vesicles, the ones derived from red blood cells (RBCEVs). Generally, employing EVs as drug carriers means managing entities with advantageous properties over synthetic vehicles or nanoparticles. Besides the fact that certain EVs also reveal intrinsic therapeutic characteristics, in regenerative medicine, EVs nanosize, lipidomic and proteomic profiles enable them to pass biologic barriers and display cell/tissue tropisms; indeed, EVs engineering can further optimize their organ targeting. In the second part of the review, we focus our attention on RBCEVs. First, we describe the biogenesis and composition of those naturally produced by red blood cells (RBCs) under physiological and pathological conditions. Afterwards, we discuss the current procedures to isolate and/or produce RBCEVs in the lab and to load a specific cargo for therapeutic exploitation. Finally, we disclose the most recent applications of RBCEVs at the in vitro and preclinical research level and their potential industrial exploitation. In conclusion, RBCEVs can be, in the near future, a very promising and versatile platform for several clinical applications and pharmaceutical exploitations.

Exosome-based delivery strategies for tumor therapy: an update on modification, loading, and clinical application

“…Polymer precipitation is a size- and density-based separation method that uses polyethylene glycol (PEG) as a medium to harvest exosomes under centrifugal conditions by reducing their solubility. Precipitation was initially employed to isolate viruses but later showed good separation efficiency when purifying exosomes [ 83 ]. This method is relatively simple to perform, requires a short analysis time, can be integrated with existing clinical techniques, and is suitable for large sample volumes.…”

Harnessing Bacterial Extracellular Vesicle Immune Effects for Cancer Therapy

“…Given that essentially all bacteria produce them, bEVs exhibit wide heterogeneity in terms of dimensions, surface elements, and molecular cargo, making this a versatile platform technology for therapeutic development [ 90 ]. In addition, bEVs have the capability to traverse biological barriers while maintaining stability in the bloodstream [ 91 , 92 ]. They also have the potential to deliver their payload with some selectivity to the TME, either by passive accumulation as biological nanoparticles [ 40 , 93 ], by engineered expression of tumor-targeting ligands [ 93 ], or by incorporation into host cells that home to tumors [ 94 ].…”

Extracellular Vesicles for Therapeutic Nucleic Acid Delivery: Loading Strategies and Challenges

“…These nanosized carriers transfer various cargoes into the body, protecting them from enzymatic degradation. The unique architecture and content of EVs have stimulated research aimed at their use as drug carriers, diagnostic markers, immunotherapeutic agents, and for regenerative medicine [ 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 ]. Two general pathways of EV formation have been described to date: via the intracellular endosomal compartments and via the separation of vesicles from the plasma membrane [ 52 ].…”

“…Due to the different approaches used to isolate and purify EVs, there are significant inconsistencies in the doses of EVs used in preclinical studies [ 61 ]. The amount of EVs is usually measured either by the total protein concentration or by the particle number in the EV preparations (techniques of EV characterizations were discussed in reviews [ 40 , 50 , 113 , 114 , 115 ]). However, the different methods for isolating EVs give different levels of contamination in the EV preparations with nonvesicular structures.…”