Tuning the Extracellular Vesicles Membrane through Fusion for Biomedical Applications

Insight into the Functional Dynamics and Challenges of Exosomes in Pharmaceutical Innovation and Precision Medicine

Of all the numerous nanosized extracellular vesicles released by a cell, the endosomal-originated exosomes are increasingly recognized as potential therapeutics, owing to their inherent stability, low immunogenicity, and targeted delivery capabilities. This review critically evaluates the transformative potential of exosome-based modalities across pharmaceutical and precision medicine landscapes. Because of their precise targeted biomolecular cargo delivery, exosomes are posited as ideal candidates in drug delivery, enhancing regenerative medicine strategies, and advancing diagnostic technologies. Despite the significant market growth projections of exosome therapy, its utilization is encumbered by substantial scientific and regulatory challenges. These include the lack of universally accepted protocols for exosome isolation and the complexities associated with navigating the regulatory environment, particularly the guidelines set forth by the U.S. Food and Drug Administration (FDA). This review presents a comprehensive overview of current research trajectories aimed at addressing these impediments and discusses prospective advancements that could substantiate the clinical translation of exosomal therapies. By providing a comprehensive analysis of both the capabilities and hurdles inherent to exosome therapeutic applications, this article aims to inform and direct future research paradigms, thereby fostering the integration of exosomal systems into mainstream clinical practice.

In Situ Labeling of the Aqueous Compartment of Extracellular Vesicles with Luminescent Gold Nanoclusters

Extracellular vesicles (EVs) are well-known membrane-limited particles secreted by both healthy and cancerous cells. They are considered as biomarkers for early cancer diagnosis and are involved in many pathologies and physiological pathways. They could serve as diagnostic tools in liquid biopsies, as therapeutics in regenerative medicine, or as drug delivery vehicles. Our aim is here to encapsulate luminescent nanoprobes in the aqueous compartment of human EVs extracted from reproductive fluids. The analysis and labeling of the EVs content with easily detectable luminescent nanoparticles could enable a powerful tool for early diagnosis of specific diseases and also for the design of new therapeutics. In this view, gold nanoclusters (AuNCs) appear as an attractive alternative as nontoxic fluorophore probes because of their luminescence properties, large window of fluorescence lifetimes (1 ns-1 μs), ultrasmall size (<2 nm), good biocompatibility, and specific ability as X-ray photosensitizers. Here, we investigated an attractive method that uses fusogenic liposomes to deliver gold nanoclusters into EVs. This approach guarantees the preservation of the EVs membrane without any breakage, thus maintaining compartmental integrity. Different lipid compositions of liposomes preloaded with AuNCs were selected to interact electrostatically with human EVs and compared in terms of fusion efficiency. The mixture of liposomes and EVs results in membrane mixing as demonstrated by FRET experiments and fusion revealed by flux cytometry and cryo-TEM. The resulting fused EVs exhibit typical fluorescence of the AuNCs together with an increased size in agreement with fusion. Moreover, the fusion events in mixtures of EVs and AuNCs preloaded liposomes were analyzed by using cryo-electron microscopy. Finally, the ratio of released AuNCs during the fusion between the fusogenic liposomes and the EVs was estimated to be less than 20 mol % by Au titration using ICP spectroscopy.

Tonicity-induced cargo loading into extracellular vesicles

The current challenge in using extracellular vesicles (EVs) as drug delivery vehicles is to precisely control their membrane permeability, specifically in the ability to switch between permeable and impermeable states without compromising their integrity and functionality. Here, we introduce a rapid, efficient, and gentle loading method for EVs based on tonicity control (TC) using a lab-on-a-disc platform. In this technique, a hypotonic solution was used for temporarily permeabilizing a membrane ("on" state), allowing the influx of molecules into EVs. The subsequent isotonic washing led to an impermeable membrane ("off" state). This loading cycle enables the loading of different cargos into EVs, such as doxorubicin hydrochloride (Dox), ssDNA, and miRNA. The TC approach was shown to be more effective than traditional methods such as sonication or extrusion, with loading yields that were 4.3-fold and 7.2-fold greater, respectively. Finally, the intracellular assessments of miRNA-497-loaded EVs and doxorubicin-loaded EVs confirmed the superior performance of TC-prepared formulations and demonstrated the impact of encapsulation heterogeneity on the therapeutic outcome, signifying potential opportunities for developing novel exosome-based therapeutic systems for clinical applications.

Gastric cancer and mesenchymal stem cell-derived exosomes: from pro-tumorigenic effects to anti-cancer vehicles

Gastric cancer (GC) is one of the most prevalent malignancies in the world, with a high mortality rate in both women and men. Conventional treatments, like chemotherapy, radiotherapy and surgery, are facing some drawbacks like acquired drug resistance and various side effects, leading to cancer recurrence and increased morbidity; thus, development of novel approaches in targeted therapy would be very beneficial. Exosomes, extracellular vesicles with a size distribution of sub-150 nm, interplay in physiological and pathophysiological cell-cell communications and can pave the way for targeted cancer therapy. Accumulating pieces of evidence have indicated that exosomes derived from mesenchymal stem cells (MSC-EXs) can act as a double-edged sword in some cancers. The purpose of this review is to assess the differences between stem cell therapy and exosome therapy. Moreover, our aim is to demonstrate how naïve MSCs transform into GC-MSCs in the tumor microenvironment. Additionally, the tumorigenic and anti-proliferation effects of MSC-EXs derived from different origins were investigated. Finally, we suggest potential modifications and combination options that involve utilizing MSC-EXs from the foreskin and umbilical cord as promising sources to enhance the efficacy of gastric cancer treatment. This approach is presented in contrast to bone marrow cells, which are more heterogeneous, age-related, and are also easily affected by the patient's circulation system.

Immunological Regulation of Gut-Tropic Immune Cells by Extracellular Vesicles

The remarkable diversity of lymphocytes, essential components of the immune system, serves as an ingenious mechanism for maximizing the efficient utilization of limited host defense resources. While cell adhesion molecules, notably in gut-tropic T cells, play a central role in this mechanism, the counterbalancing molecular details have remained elusive. Conversely, we've uncovered the molecular pathways enabling extracellular vesicles secreted by lymphocytes to reach the gut's mucosal tissues, facilitating immunological regulation. This discovery sheds light on immune fine-tuning, offering insights into immune regulation mechanisms.

Extracellular Vesicles as Delivery Systems in Disease Therapy

Extracellular vesicles (EVs)/exosomes are nanosized membrane-bound structures that are released by virtually all cells. EVs have attracted great attention in the scientific community since the discovery of their roles in cell-to-cell communication. EVs' enclosed structure protects bioactive molecules from degradation in the extracellular space and targets specific tissues according to the topography of membrane proteins. Upon absorption by recipient cells, EV cargo can modify the transcription machinery and alter the cellular functions of these cells, playing a role in disease pathogenesis. EVs have been tested as the delivery system for the mRNA COVID-19 vaccine. Recently, different therapeutic strategies have been designed to use EVs as a delivery system for microRNAs and mRNA. In this review, we will focus on the exciting and various platforms related to using EVs as delivery vehicles, mainly in gene editing using CRISPR/Cas9, cancer therapy, drug delivery, and vaccines. We will also touch upon their roles in disease pathogenesis.

Recent Trends in the Use of Small Extracellular Vesicles as Optimal Drug Delivery Vehicles in Oncology

Small extracellular vesicles (sEVs) are produced by most cells and play an important role in cell-to-cell communication and maintaining cellular homeostasis. Their ability to transfer biological cargo to target cells makes them a promising tool for cancer drug delivery. Advances in sEV engineering, EV mimetics, and ligand-directed targeting have improved the efficacy of anticancer drug delivery and functionality. EV-based RNA interference and hybrid miRNA transfer have also been extensively used in various preclinical cancer models. Despite these developments, gaps still exist in our understanding of using sEVs to treat solid tumor malignancies effectively. This article provides an overview of the last five years of sEV research and its current status for the efficient and targeted elimination of cancer cells, which could advance cancer research and bring sEV formulations into clinical use.