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

Harnessing exosomes for targeted drug delivery systems to combat brain cancer

Brain cancer remains a significant challenge in the field of oncology, primarily because of its aggressive nature and the limited treatment options available. Conventional therapies often fall short in effectively targeting tumor cells, while sparing healthy brain tissue from collateral damage. However, exosomes are now recognized as promising nanocarriers for targeted drug delivery. These naturally occurring extracellular vesicles can cross the blood-brain barrier and selectively interact with cancer cells. Utilizing exosomes as drug delivery vehicles offers a novel approach with significant potential for targeted therapy. By encapsulating therapeutic agents within exosomes, drugs can be specifically targeted to tumor cells, maximizing their impact whilst minimizing damage to healthy brain tissue. Furthermore, exosomes can be modified to display molecules that specifically recognize and bind to cancer cells, further enhancing their precision and efficacy. While exosome-based therapies show potential, scalability, purification, and clinical application challenges remain. The scalability of exosome production, purification, and modification techniques remains a hurdle that must be overcome for clinical translation. Additionally, the intricate interactions between the tumor microenvironment and exosomes necessitate further research to optimize therapeutic outcomes. The review explores applications and future perspectives of exosome-based therapies in advancing targeted brain cancer treatment.

Red blood cells could protect miRNAs from degradation or loss thanks to Argonaute 2 binding

Red blood cells (RBCs) have emerged as reservoirs of microRNAs (miRNAs) in the circulatory system, challenging the traditional view of their nucleic acid absence. This study investigates the miRNA profiles and stability of both native and engineered RBCs. We demonstrate that RBCs are rich in miRNAs, which remain stable under physiological conditions, likely due to their association with Ago2, a key RNA-binding protein. The stability and retention of miRNAs persist even after hypotonic dialysis used for RBC engineering. These findings underline the potential of RBCs as miRNA carriers for therapeutic applications and as a foundation for RNA-based delivery systems. Such advancements could redefine their role in transfusion medicine and advanced RNA therapies.

Exosomes: from basic research to clinical diagnostic and therapeutic applications in cancer

Cancer continues to pose a global threat despite potent anticancer drugs, often accompanied by undesired side effects. To enhance patient outcomes, sophisticated multifunctional approaches are imperative. Small extracellular vesicles (EVs), a diverse family of naturally occurring vesicles derived from cells, offer advantages over synthetic carriers. Among the EVs, the exosomes are facilitating intercellular communication with minimal toxicity, high biocompatibility, and low immunogenicity. Their tissue-specific targeting ability, mediated by surface molecules, enables precise transport of biomolecules to cancer cells. Here, we explore the potential of exosomes as innovative therapeutic agents, including cancer vaccines, and their clinical relevance as biomarkers for clinical diagnosis. We highlight the cargo possibilities, including nucleic acids and drugs, which make them a good delivery system for targeted cancer treatment and contrast agents for disease monitoring. Other general aspects, sources, and the methodology associated with therapeutic cancer applications are also reviewed. Additionally, the challenges associated with translating exosome-based therapies into clinical practice are discussed, together with the future prospects for this innovative approach.

Exploring the potential of plasma and adipose mesenchymal stem cell-derived extracellular vesicles as novel platforms for neuroinflammation therapy

Persistent reactive oxygen species (ROS) and neuroinflammation contribute to the onset and progression of neurodegenerative diseases, underscoring the need for targeted therapeutic strategies to mitigate these effects. Extracellular vesicles (EVs) show promise in drug delivery due to their biocompatibility, ability to cross biological barriers, and specific interactions with cell and tissue receptors. In this study, we demonstrated that human plasma-derived EVs (pEVs) exhibit higher brain-targeting specificity, while adipose-derived mesenchymal stem cells EVs (ADMSC-EVs) offer regenerative and immunomodulatory properties. We further investigated the potential of these EVs as therapeutic carriers for brain-targeted drug delivery, using Donepezil (DNZ) as the model drug. DNZ, a cholinesterase inhibitor commonly used for Alzheimer's disease (AD), also has neuroprotective and anti-inflammatory properties. The size of EVs used ranged from 50 to 300 nm with a surface charge below -30 mV. Both formulations showed rapid cellular internalization, without toxicity, and the ability to cross the blood-brain barrier (BBB) in a zebrafish model. The have analyzed the anti-inflammatory and antioxidant actions of pEVs-DNZ and ADMSC-EVs-DNZ in the presence of lipopolysaccharide (LPS). ADMSC-EVs significantly reduced the inflammatory mediators released by HMC3 microglial cells while treatment with pEVs-DNZ and ADMSC-EVs-DNZ lowered both phagocytic activity and ROS levels in these cells. In vivo experiments using zebrafish larvae revealed that both EV formulations reduced microglial proliferation and exhibited antioxidant effects. Overall, this study highlights the potential of EVs loaded with DNZ as a novel approach for treating neuroinflammation underlying various neurodegenerative diseases.

Self-Assembly of Silole-Based Aggregation-Induced Emission Compounds with Green Fluorescent Protein under Physiological Conditions for Traceable and Versatile Drug Delivery

Biomacromolecules are viewed as promising drugs due to their specific functions in biological processes, biocompatibility, and pharmacological efficacy. Injective administration, chosen to avoid intestinal barriers, may in turn lead to immediate decay in the circulation system, unreliable targeting performance, or the induction of immune responses. For some biomacromolecules, chemically modified proteins have been developed for practical use. Various cargo or carrier systems are under development but have been delayed by technical difficulties. We present self-assembled nanocapsules with diameters ranging from 100 to 500 nm that can be deployed in physiological buffers to enclose various substances present in the buffers at the same time. Our amphiphilic nanocapsule, consisting of silole-core dendrimer products as the hydrophobic part and green fluorescent protein (GFP) derivatives as the hydrophilic part, connects and assembles spontaneously when mixed in solutions while engulfing dissolved or dispersed compounds together in a dose-dependent manner and shows unique optical characteristics because the dendrimer products exhibit aggregation-induced emission. Furthermore, the emission of the dendrimer causes considerable fluorescence resonance energy transfer (FRET) to GFP derivatives upon association. We could easily monitor assemblies by FRET states and particle sizes and have confirmed a stable presence in the buffer for at least a month. Further tracking of nanocapsules by fluorescence confirmed efficient uptake into some cancer cells. Nanocapsules based on GFP variants with or without a cell-surface-specific tag demonstrated that the tag improved the potential for specific targeted delivery. There were also indications that the nanocapsules became unstable after cellular uptake in the intracellular environment. We report here the simple preparation of traceable, stable, and biocompatible self-assembled nanocapsules as the basis for a versatile drug delivery system.

Umbilical Cord Mesenchymal Stem Cell-Derived Extracellular Vesicles as Natural Nanocarriers in the Treatment of Nephrotoxic Injury In Vitro

Umbilical cord mesenchymal stem cell-derived extracellular vesicles (UC-EVs) are valuable in nanomedicine as natural nanocarriers, carrying information molecules from their parent cells and fusing with targeted cells. miRNA-126, specific to endothelial cells and derived from these vesicles, supports vascular integrity and angiogenesis and has protective effects in kidney diseases.

OBJECTIVE

This study investigates the delivery of miRNA-126 and anti-miRNA-126 via UC-EVs as natural nanocarriers for treating nephrotoxic injury in vitro.

METHOD

The umbilical cord-derived mesenchymal stem cell and UC-EVs were characterized according to specific guidelines. Rat kidney proximal tubular epithelial cells (tubular cells) were exposed to nephrotoxic injury through of gentamicin and simultaneously treated with UC-EVs carrying miRNA-126 or anti-miRNA-126. Specific molecules that manage cell cycle progression, proliferation cell assays, and newly synthesized DNA and DNA damage markers were evaluated.

RESULTS

We observed significant increases in the expression of cell cycle markers, including PCNA, p53, and p21, indicating a positive cell cycle regulation with newly synthesized DNA via BrDU. The treatments reduced the expression of DNA damage marker, such as H2Ax, suggesting a lower rate of cellular damage.

CONCLUSIONS

The UC-EVs, acting as natural nanocarriers of miRNA-126 and anti-miRNA-126, offer nephroprotective effects in vitro. Additionally, other components in UC-EVs, such as proteins, lipids, and various RNAs, might also contribute to these effects.

Extracellular vesicles

Cells, pathogens, and other systems release extracellular vesicles (EVs). The particles promote intercellular communication and contain proteins, lipids, RNA and DNA. Initially considered to be cellular waste in the twentieth century, EVs were becoming recognized for their function in biological communication and control. EVs are divided into many subtypes: exosomes, microvesicles, and apoptotic bodies. Exosomes form in the late endosome/multivesicular body and are released when the compartments fuse with the plasma membrane. Microvesicles are generated by direct budding of the plasma membrane, whereas apoptotic bodies are formed after cellular apoptosis. The new guideline for EVs that describes alternate nomenclature for EVs. The particles modulate the immune response by affecting both innate and adaptive immunity, and their specific the structure allows them to be used as biomarkers to diagnose a variety of diseases. EVs have a wide range of applications, for example, delivery systems for medications and genetic therapies because of their ability to convey specific cellular material. In anti-tumor therapy, EVs deliver therapeutic chemicals to tumor cells. The EVs promote transplant compatibility and reduce organ rejection. Host-parasite interactions, therapeutic and diagnostic for cancer, cardiovascular disease, cardiac tissue regeneration, and the treatment of neurological diseases such as Alzheimer's and Parkinson's. The study of EVs keeps on expanding, revealing new functions and beneficial options. EVs have the potential to change drug delivery, diagnostics, and specific therapeutics, creating a new frontier in biomedical.

Quantitative Analysis of Complement Membrane Attack Complex Proteins Associated with Extracellular Vesicles

Extracellular vesicles (EVs) represent a universal mechanism of intercellular communication in normal and pathological conditions. There are reports showing the presence of complement proteins in EV preparations, specifically those that can form a membrane attack complex (MAC). In the present work, we have used a quantitative mass spectrometry method that allows for the measurement of multiple targeted proteins in one experimental run. The quantification of MAC-forming proteins, namely C5b, C6, C7, C8, and C9, in highly purified EVs from normal human plasma revealed the presence of MAC proteins at approximately equal stoichiometry that does not fit the expected stoichiometry of preformed MAC. We concluded that while MAC proteins can be associated with EVs from normal plasma and presumably can be delivered to the recipient cells, there is no evidence that the EVs carry preformed MAC.

Efficient and highly reproducible production of red blood cell-derived extracellular vesicle mimetics for the loading and delivery of RNA molecules

Extracellular vesicles (EVs) are promising natural nanocarriers for the delivery of therapeutic agents. As with any other kind of cell, red blood cells (RBCs) produce a limited number of EVs under physiological and pathological conditions. Thus, RBC-derived extracellular vesicles (RBCEVs) have been recently suggested as next-generation delivery systems for therapeutic purposes. In this paper, we show that thanks to their unique biological and physicochemical features, RBCs can be efficiently pre-loaded with several kinds of molecules and further used to generate RBCEVs. A physical vesiculation method, based on "soft extrusion", was developed, producing an extremely high yield of cargo-loaded RBCEV mimetics. The RBCEVs population has been deeply characterized according to the new guidelines MISEV2023, showing great homogeneity in terms of size, biological features, membrane architecture and cargo. In vitro preliminary results demonstrated that RBCEVs are abundantly internalized by cells and exert peculiar biological effects. Indeed, efficient loading and delivery of miR-210 by RBCEVs to HUVEC has been proven, as well as the inhibition of a known mRNA target. Of note, the bench-scale process can be scaled-up and translated into clinics. In conclusion, this investigation could open the way to a new biomimetic platform for RNA-based therapies and/or other therapeutic cargoes useful in several diseases.

Harnessing Bacterial Extracellular Vesicle Immune Effects for Cancer Therapy

There are a growing number of studies linking the composition of the human microbiome to disease states and treatment responses, especially in the context of cancer. This has raised significant interest in developing microbes and microbial products as cancer immunotherapeutics that mimic or recapitulate the beneficial effects of host-microbe interactions. Bacterial extracellular vesicles (bEVs) are nano-sized, membrane-bound particles secreted by essentially all bacteria species and contain a diverse bioactive cargo of the producing cell. They have a fundamental role in facilitating interactions among cells of the same species, different microbial species, and even with multicellular host organisms in the context of colonization (microbiome) and infection. The interaction of bEVs with the immune system has been studied extensively in the context of infection and suggests that bEV effects depend largely on the producing species. They thus provide functional diversity, while also being nonreplicative, having inherent cell-targeting qualities, and potentially overcoming natural barriers. These characteristics make them highly appealing for development as cancer immunotherapeutics. Both natively secreted and engineered bEVs are now being investigated for their application as immunotherapeutics, vaccines, drug delivery vehicles, and combinations of the above, with promising early results. This suggests that both the intrinsic immunomodulatory properties of bEVs and their ability to be modified could be harnessed for the development of next-generation microbe-inspired therapies. Nonetheless, there remain major outstanding questions regarding how the observed preclinical effectiveness will translate from murine models to primates, and humans in particular. Moreover, research into the pharmacology, toxicology, and mass manufacturing of this potential novel therapeutic platform is still at early stages. In this review, we highlight the breadth of bEV interactions with host cells, focusing on immunologic effects as the main mechanism of action of bEVs currently in preclinical development. We review the literature on ongoing efforts to develop natively secreted and engineered bEVs from a variety of bacterial species for cancer therapy and finally discuss efforts to overcome outstanding challenges that remain for clinical translation.

Platelet-derived drug delivery systems: Pioneering treatment for cancer, cardiovascular diseases, infectious diseases, and beyond

Platelets play a critical role as circulating cells in the human body and contribute to essential physiological processes such as blood clotting, hemostasis, vascular repair, and thrombus formation. Currently, platelets are extensively employed in the development of innovative biomimetic drug delivery systems, offering significant enhancements in circulation time, biocompatibility, and targeted delivery efficiency compared to conventional drug delivery approaches. Leveraging the unique physiological functions of platelets, these platelet-derived drug delivery systems (DDSs) hold great promise for the treatment of diverse diseases, including cancer, cardiovascular diseases, infectious diseases, wound healing and other diseases. This review primarily focuses on the design and characteristics of existing platelet-derived DDSs, including their preparation and characterization methods. Furthermore, this review comprehensively outlines the applications of these materials across various diseases, offering a holistic understanding of their therapeutic potential. This study aimed to provide a comprehensive overview of the potential value of these materials in clinical treatment, serving as a valuable reference for the advancement of novel platelet-derived DDSs and their broader utilization in the field of disease treatment.

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

Malignancy is a major public health problem and among the leading lethal diseases worldwide. Although the current tumor treatment methods have therapeutic effect to a certain extent, they still have some shortcomings such as poor water solubility, short half-life, local and systemic toxicity. Therefore, how to deliver therapeutic agent so as to realize safe and effective anti-tumor therapy become a problem urgently to be solved in this field. As a medium of information exchange and material transport between cells, exosomes are considered to be a promising drug delivery carrier due to their nano-size, good biocompatibility, natural targeting, and easy modification. In this review, we summarize recent advances in the isolation, identification, drug loading, and modification of exosomes as drug carriers for tumor therapy alongside their application in tumor therapy. Basic knowledge of exosomes, such as their biogenesis, sources, and characterization methods, is also introduced herein. In addition, challenges related to the use of exosomes as drug delivery vehicles are discussed, along with future trends. This review provides a scientific basis for the application of exosome delivery systems in oncological therapy.

Drug transport by red blood cells

This review focuses on the role of human red blood cells (RBCs) as drug carriers. First, a general introduction about RBC physiology is provided, followed by the presentation of several cases in which RBCs act as natural carriers of drugs. This is due to the presence of several binding sites within the same RBCs and is regulated by the diffusion of selected compounds through the RBC membrane and by the presence of influx and efflux transporters. The balance between the influx/efflux and the affinity for these binding sites will finally affect drug partitioning. Thereafter, a brief mention of the pharmacokinetic profile of drugs with such a partitioning is given. Finally, some examples in which these natural features of human RBCs can be further exploited to engineer RBCs by the encapsulation of drugs, metabolites, or target proteins are reported. For instance, metabolic pathways can be powered by increasing key metabolites (i.e., 2,3-bisphosphoglycerate) that affect oxygen release potentially useful in transfusion medicine. On the other hand, the RBC pre-loading of recombinant immunophilins permits increasing the binding and transport of immunosuppressive drugs. In conclusion, RBCs are natural carriers for different kinds of metabolites and several drugs. However, they can be opportunely further modified to optimize and improve their ability to perform as drug vehicles.

Extracellular Vesicles: Emergent and Multiple Sources in Wound Healing Treatment

Non-healing wound- and tissue-injury are commonly experienced worldwide by the aging population. The persistence of disease commonly leads to tissue infection, resulting in severe clinical complications. In the last decade, extracellular vesicles (EVs) have been considered promising and emergent therapeutic tools to improve the healing processes. Therefore, efforts have been directed to develop a cell-free therapeutic platform based on EV administration to orchestrate tissue repair. EVs derived from different cell types, including fibroblast, epithelial, and immune cells are recruited to the injured sites and in turn take part in scar formation. EVs are nano-sized particles containing a heterogeneous cargo consisting of lipids, proteins, and nucleic acids protected from degradation by their lipid bilayer. Noteworthy, since EVs have natural biocompatibility and low immunogenicity, they represent the ideal therapeutic candidates for regenerative purposes. Indeed, EVs are released by several cell types, and even if they possess unique biological properties, their functional capability can be further improved by engineering their content and functionalizing their surface, allowing a specific cell cargo delivery. Herein, we provide an overview of preclinical data supporting the contribution of EVs in the repair and regenerative processes, focusing on different naïve EV sources, as well as on their engineering, to offer a scalable and low-cost therapeutic option for tissue repair.

Platelet-derived extracellular vesicles for drug delivery

Platelet-derived extracellular vesicles (PEVs) are a subset of EVs that are released from platelets, which are small nuclear cell fragments that play a critical role in hemostasis and thrombosis. PEVs have been shown to have important roles in a variety of physiological and pathological processes, including inflammation, angiogenesis, and cancer. Recently, researchers, including our group have utilized PEVs as drug delivery platforms as PEVs could target inflammatory sites both passively and actively. This review summarizes the biological function of PEVs, introduces recent applications of PEVs in targeted drug delivery, and provides an outlook for the further development of utilizing PEVs for drug delivery.

Size-exclusion chromatography for the characterization of urinary extracellular vesicles

In recent years, extracellular vesicles (EVs) have gained attention for their potential as biomarkers for the early diagnosis and treatment of various diseases. Traditionally, EV isolation has relied exclusively on ultracentrifugation. However, alternative enrichment methods such as size-exclusion chromatography (SEC) and polyethylene glycol-based precipitation have been introduced. This study utilized SEC as a characterization tool to assess the efficiency of EV isolation. Urinary EVs isolated from human urine using centrifugation (40,000 × g) were analyzed using an SEC column with a pore size of 1000 Å, an inner diameter of 7.8 mm, and a length of 300 mm. The EVs were detected sequentially using UV (280 nm) and fluorescence (λex/em = 550 nm/565 nm); the EVs were observed at approximately 6 min, while the proteins were observed at approximately 12 min. The repeated centrifugation enrichment steps resulted in an increase in EV peaks and a decrease in protein peaks. SEC analysis of the enriched EV samples confirmed that a four-cycle repetition of centrifugation is necessary for successful EV enrichment and removal of non-EV proteins from 40 mL of human urine.

Membrane Vesicles as Drug Delivery Systems: Source, Preparation, Modification, Drug Loading, In Vivo Administration and Biodistribution, and Application in Various Diseases

Bioinspired (or biologically inspired) drug delivery systems (DDSs) have been intensively studied in the last decades. As bioinspired DDSs, membrane vesicles, including extracellular vesicles (EVs) released from eukaryotic cells, outer membrane vesicles (OMVs) from bacteria, cell-bound membrane vesicles (CBMVs) isolated in situ from cell surfaces, membrane vesicles reorganized after the isolation of the plasma membrane of cells, and others have been rapidly developed and are attracting more and more attention. Most recently, a collection of 25 papers on the advances in membrane vesicle-based drug delivery systems was published in a Special Issue of Pharmaceutics entitled "Advances of membrane vesicles in drug delivery systems". These papers cover many related topics including the source, preparation, modification, drug loading, and in vivo administration and biodistribution of membrane vesicles (mainly extracellular vesicles or exosomes and bacterial outer membrane vesicles), as well as application of membrane vesicles as DDSs in the treatment of various diseases.

Preclinical and clinical developments in enzyme-loaded red blood cells: an update

INTRODUCTION

We have previously described the preclinical developments in enzyme-loaded red blood cells to be used in the treatment of several rare diseases, as well as in chronic conditions.

AREA COVERED

Since our previous publication we have seen further progress in the previously discussed approaches and, interestingly enough, in additional new studies that further strengthen the idea that red blood cell-based therapeutics may have unique advantages over conventional enzyme replacement therapies in terms of efficacy and safety. Here we highlight these investigations and compare, when possible, the reported results versus the current therapeutic approaches.

EXPERT OPINION

The continuous increase in the number of new potential applications and the progress from the encapsulation of a single enzyme to the engineering of an entire metabolic pathway open the field to unexpected developments and confirm the role of red blood cells as cellular bioreactors that can be conveniently manipulated to acquire useful therapeutic metabolic abilities. Positioning of these new approaches versus newly approved drugs is essential for the successful transition of this technology from the preclinical to the clinical stage and hopefully to final approval.

Viral Vectors, Exosomes, and Vexosomes: Potential Armamentarium for Delivering CRISPR/Cas to Cancer Cells

The underlying cause of cancer is genetic disruption, so gene editing technologies, particularly CRISPR/Cas systems can be used to go against cancer. The field of gene therapy has undergone many transitions over its 40-year history. Despite its many successes, it has also suffered many failures in the battle against malignancies, causing really adverse effects instead of therapeutic outcomes. At the tip of this double-edged sword are viral and non-viral-based vectors, which have profoundly transformed the way scientists and clinicians develop therapeutic platforms. Viruses such as lentivirus, adenovirus, and adeno-associated viruses are the most common viral vectors used for delivering the CRISPR/Cas system into human cells. In addition, among non-viral vectors, exosomes, especially tumor-derived exosomes (TDEs), have proven to be quite effective at delivering this gene editing tool. The combined use of viral vectors and exosomes, called vexosomes, seems to be a solution to overcoming the obstacles of both delivery systems.

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

Extracellular vesicles (EVs) are membrane vesicles released into the extracellular milieu by cells of various origins. They contain different biological cargoes, protecting them from degradation by environmental factors. There is an opinion that EVs have a number of advantages over synthetic carriers, creating new opportunities for drug delivery. In this review, we discuss the ability of EVs to function as carriers for therapeutic nucleic acids (tNAs), challenges associated with the use of such carriers in vivo, and various strategies for tNA loading into EVs.