The impact of storage on extracellular vesicles: A systematic study

Engineered extracellular vesicles: an emerging nanomedicine therapeutic platform

The intercellular communication role of extracellular vesicles has been widely proved in various organisms. Compelling evidence has illustrated the involvement of these vesicles in both physiological and pathological processes. Various studies indicate that extracellular vesicles surpass conventional synthetic drug carriers, owing to their abundance in organisms, enhanced targeting ability and low immunogenicity. Therefore, extracellular vesicles have been deemed to be potential drug carriers for the treatment of various diseases, and related studies have increased rapidly. Here, we intend to provide a comprehensive and in-depth review of recent advances in the sources, delivery function, extraction and cargo-loading technologies of extracellular vesicles, as well as their clinical potential in constructing emerging nanomedicine therapeutic platforms. In particular, microfluidic-based isolation and drug-loading technologies, as well as the treatment of various diseases, are highlighted. We also make comparisons between extracellular vesicles and other conventional drug carriers and discuss the challenges in developing drug delivery platforms for clinical translation.

Harnessing extracellular vesicle-mediated crosstalk between T cells and cancer cells for therapeutic applications

Small extracellular vesicles (EVs) are a diverse group of lipid-based particles that are ≤200 nm in diameter and contain an aqueous core. EVs have been shown to mediate intercellular communications between a wide array of immune cells; the downstream effects are diverse and have potential implications for the development of novel immunotherapeutic treatments. Despite a high volume of studies addressing the role EVs play in the immune system, our understanding of the crosstalk between T cells and cancer cells remains limited. Here, we discuss how EVs derived from cancer cells modulate T cell functions and conversely, how T cell derived EVs are crucial in modulating adaptive immune functions. In the context of cancer, tumor derived EVs (TD-EVs) halt T cell-mediated immunity by interfering with effector functions and enhancing regulatory T cell (Treg) functions. In contrast, EVs derived from effector T cells can serve to stimulate anticancer immunity, curbing metastasis and tumor growth. These findings highlight important aspects of how EVs can both mediate the therapeutic effects of T cells as well as impair T cell-mediated immunity. This calls for a deeper understanding of EV-mediated effects in order to advance them as next-generation therapeutics and nanocarriers.

Neural progenitor cell-derived exosomes in ischemia/reperfusion injury in cardiomyoblasts

The physiologic relationship between the brain and heart is emerging as a novel therapeutic target for clinical intervention for acute myocardial infarction. In the adult human brain, vestigial neuronal progenitor stem cells contribute to neuronal repair and recovery following cerebral ischemic injury, an effect modulated by secreted exosomes. Ischemia conditioned neuronal cell derived supernatant and experimental stroke has been shown to be injurious to the heart. However, whether unconditioned neuronal progenitor cell derived-exosomes can instead protect myocardium represents a profound research gap. We investigated the effects of unconditioned neural stem cell derived exosomes as post-injury treatment for cardiomyoblasts from three neuronal culture conditions; adherent cultures, neurosphere cultures and bioreactor cultures. Small extracellular vesicles were enriched with serial ultracentrifugation, validated via nanoparticle tracking analysis, transmission electron microscopy and Western blot analysis prior to utilization as post-injury treatment for H9c2 cardiomyoblasts following oxygen and glucose deprivation. LDH assay was used to assess viability and Seahorse XF high-resolution respirometry analyzer to investigate post-injury cardiomyocyte bioenergetics. We found no evidence that unconditioned neural stem cell derived exosomes are cardiotoxic nor cardioprotective to H9c2 cardiomyoblasts following ischemia-reperfusion injury. Based on our findings, utilizing unconditioned neural stem cell derived exosomes as post-injury treatment for other organs should not have adverse effects to the damaged cardiac cells.

A study on the production of extracellular vesicles derived from novel immortalized human placental mesenchymal stromal cells

Extracellular vesicles (EVs) are not only involved in cell-to-cell communications but have other functions as "garbage bags", as bringing nutrients to cells, and as inducing mineral during bone formation and ectopic calcification. These minuscule entities significantly contribute to the regulation of bodily functions. However, the clinical application of EVs faces challenges due to limited production yield and targeting efficiency. In our study, we propose a method for efficiently harvesting EVs utilizing simian virus 40 large T antigen (SV40LT) immortalized human placental chorionic mesenchymal stromal cells (CMSCs). We investigated immortalized placental chorionic mesenchymal stromal cells (imCMSCs), a stromal cell line that surpasses the growth limitations of primary passage cells while retaining phenotypic characteristics and differentiation potential. This development offers the prospect of a consistent, uniform source of EVs, which is essential for regenerative medicine. Our findings indicate that the immortalization process preserves the particle size, quantity and surface marker profiles of EVs, providing a possible approach to produce high-yield EVs suitable for disease diagnosis and treatment.

Extracellular vesicles in ageing cold-stored whole blood may not compensate for the decreasing haemostatic function in vitro

BACKGROUND

Extracellular vesicles (EVs) have procoagulative properties. As EVs are known to accumulate in stored blood products, we compared the EV content and coagulation capacity of leukoreduced cold-stored whole blood (CSWB) with current prehospital and in-hospital component therapies to understand the role of EVs in the haemostatic capacity of ageing CSWB.

MATERIALS AND METHODS

Blood was obtained from 12 O RhD-positive male donors. CSWB was compared with in-hospital component therapy of red blood cells (RBCs), OctaplasLG and buffy-coat platelets and prehospital component therapy of RBC and lyophilized plasma. Samples were drawn on Days 1 and 14 of CSWB and RBC cold storage. Blood count, haemolysis markers, rotational thromboelastometry, sonorheometry and thrombin generation were analysed. EVs were analysed using nanoparticle tracking analysis and cellular origin was determined using imaging flow cytometry.

RESULTS

There was a trend towards increased production of both platelet and RBC-derived EVs during CSWB storage. Particle count increased during storage, whereas thrombin generation slowed down and in viscoelastic assays, clotting times prolonged, clot formation became impaired, and stiffness of the resulting clot decreased.

CONCLUSION

Both platelet and RBC-derived EVs increased in number in CSWB during storage. This did not appear to compensate for the in vitro decreasing haemostatic capacity of ageing CSWB, suggesting EVs produced during storage may not have active procoagulative effects, but rather reflect the ageing of blood cells.

Amniotic fluid stem cell extracellular vesicles as a novel fetal therapy for pulmonary hypoplasia: a review on mechanisms and translational potential

Disruption of developmental processes affecting the fetal lung leads to pulmonary hypoplasia. Pulmonary hypoplasia results from several conditions including congenital diaphragmatic hernia (CDH) and oligohydramnios. Both entities have high morbidity and mortality, and no effective therapy that fully restores normal lung development. Hypoplastic lungs have impaired growth (arrested branching morphogenesis), maturation (decreased epithelial/mesenchymal differentiation), and vascularization (endothelial dysfunction and vascular remodeling leading to postnatal pulmonary hypertension). Herein, we discuss the pathogenesis of pulmonary hypoplasia and the role of microRNAs (miRNAs) during normal and pathological lung development. Since multiple cells and pathways are altered, the ideal strategy for hypoplastic lungs is to deliver a therapy that addresses all aspects of abnormal lung development. In this review, we report on a novel regenerative approach based on the administration of extracellular vesicles derived from amniotic fluid stem cells (AFSC-EVs). Specifically, we describe the effects of AFSC-EVs in rodent and human models of pulmonary hypoplasia, their mechanism of action via release of their cargo, including miRNAs, and their anti-inflammatory properties. We also compare cargo contents and regenerative effects of EVs from AFSCs and mesenchymal stromal cells (MSCs). Overall, there is compelling evidence that antenatal administration of AFSC-EVs rescues multiple features of fetal lung development in experimental models of pulmonary hypoplasia. Lastly, we discuss the steps that need to be taken to translate this promising EV-based therapy from the bench to the bedside. These include strategies to overcome barriers commonly associated with EV therapeutics and specific challenges related to stem cell-based therapies in fetal medicine.

Stabilizing milk-derived extracellular vesicles (mEVs) through lyophilization: a novel trehalose and tryptophan formulation for maintaining structure and Bioactivity during long-term storage

Extracellular vesicles (EVs) are widely investigated for their implications in cell-cell signaling, immune modulation, disease pathogenesis, cancer, regenerative medicine, and as a potential drug delivery vector. However, maintaining integrity and bioactivity of EVs between Good Manufacturing Practice separation/filtration and end-user application remains a consistent bottleneck towards commercialization. Milk-derived extracellular vesicles (mEVs), separated from bovine milk, could provide a relatively low-cost, scalable platform for large-scale mEV production; however, the reliance on cold supply chain for storage remains a logistical and financial burden for biologics that are unstable at room temperature. Herein, we aim to characterize and engineer a freeze-dried, mEV formulation that can be stored at room temperature without sacrificing structure/bioactivity and can be reconstituted before delivery. In addition to undertaking established mEV assays of structure and function on our preparations, we introduce a novel, efficient, high throughput assay of mEV bioactivity based on Electric Cell Substrate Impedance Sensing (ECIS) in Human dermal fibroblast monolayers. By adding appropriate excipients, such as trehalose and tryptophan, we describe a protective formulation that preserves mEV bioactivity during long-term, room temperature storage. Our identification of the efficacy of tryptophan as a novel additive to mEV lyophilization solutions could represent a significant advancement in stabilizing small extracellular vesicles outside of cold storage conditions.

Extracellular Vesicles Derived from Human Umbilical Mesenchymal Stem Cells Transfected with miR-7704 Improved Damaged Cartilage and Reduced Matrix Metallopeptidase 13

We aimed to explore the therapeutic efficacy of miR-7704-modified extracellular vesicles (EVs) derived from human umbilical cord mesenchymal stem cells (HUCMSCs) for osteoarthritis (OA) treatment. In vitro experiments demonstrated the successful transfection of miR-7704 into HUCMSCs and the isolation of EVs from these cells. In vivo experiments used an OA mouse model to assess the effects of the injection of miR-7704-modified EVs intra-articularly. Walking capacity (rotarod test), cartilage morphology, histological scores, and the expression of type II collagen, aggrecan, interleukin-1 beta, and matrix metalloproteinase 13 (MMP13) in the cartilage were evaluated. The EVs were characterized to confirm their suitability for therapeutic use. IL-1beta-treated chondrocytes increased type II collagen and decreased MMP13 after treatment with miR-7704-overexpressed EVs. In vivo experiments revealed that an intra-articular injection of miR-7704-overexpressed EVs significantly improved walking capacity, preserved cartilage morphology, and resulted in higher histological scores compared to in the controls. Furthermore, the decreased expression of MMP13 in the cartilage post treatment suggests a potential mechanism for the observed therapeutic effects. Therefore, miR-7704-overexpressed EVs derived from HUCMSCs showed potential as an innovative therapeutic strategy for treating OA. Further investigations should focus on optimizing dosage, understanding mechanisms, ensuring safety and efficacy, developing advanced delivery systems, and conducting early-phase clinical trials to establish the therapeutic potential of HUCMSC-derived EVs for OA management.

Dental pulp stem cell‑derived extracellular vesicles loaded with hydrogels promote osteogenesis in rats with alveolar bone defects

Alveolar bone defects caused by inflammation, trauma and tumors adversely affect periodontal health, causing tooth loosening or dentition defects, thus affecting denture or implant repair. Advancements in tissue engineering technology and stem cell biology have significantly improved the regenerative reconstruction of alveolar bone defects. The multiple trophic activities of extracellular vesicles (EVs) produced by mesenchymal stem cells play important roles in exerting their therapeutic effects. Several studies have reported the role of dental pulp stem cells (DPSCs) in bone regeneration, but the regenerative effects of DPSC‑EVs on alveolar bone defects are unclear. In the present study, the osteogenic effects of DPSC‑EVs on Hertwig's epithelial root sheath (HERS) cells in vitro and their osteoinductive effects in an alveolar bone defect rat model were investigated. The results showed that DPSC‑EVs significantly promoted the expression of osteogenic genes, such as runt‑related transcription factor 2 and alkaline phosphatase, and increased the osteogenic differentiation capability of HERS. These findings suggested that transforming growth factor β1 inhibition decreased DPSC‑EV‑induced Smad, MAPK and ERK phosphorylation in HERS. In vivo, DPSC‑EV‑loaded hydrogels were transplanted into the alveolar sockets of Sprague‑Dawley rats and observed for eight weeks. The new bone grew concentrically in the DPSC‑EV or DPSC‑EV‑loaded hydrogel group, with greater bone mass than that in the control group, and the bone volume/total volume increased notably. The results confirmed the osteogenic and osteoinductive effects of DPSC‑EVs and DPSC‑Exo‑loaded hydrogels on alveolar bone defects. Due to their low immunogenicity, high stability, good biocompatibility and osteogenic propensity, DPSC‑EV‑loaded hydrogels are a safe cell‑free therapeutic approach for defective alveolar bone regeneration.

Investigating the Potential of Extracellular Vesicles as Delivery Systems for Chemotherapeutics

BACKGROUND/OBJECTIVES

Standard chemotherapy is generally considered the best approach to treat many solid cancers, even accounting for severe side effects. Therefore, the development of a drug delivery system for chemotherapeutic administration could significantly improve standard chemotherapy by maintaining the cytotoxic effects of the drugs while decreasing the inherent side effects of the treatment. The aim of our study is the optimization of a loading strategy that conjugates the use of extracellular vesicles (EVs) as drug delivery carriers, by preserving their integrity, with the loading efficiency and activity maintenance of chemotherapeutics.

METHODS

We compared the EV loading of the chemotherapeutics epirubicin, mitomycin, methotrexate and mitoxantrone by co-incubation. Once loaded, the activity of drug-carrying EVs was tested on cancer cells and compared to that of free chemotherapeutics.

RESULTS

We defined a linear correlation between chemotherapeutics' concentration and their absorbance at the drug-specific wavelength, which allowed the definition of a highly sensitive absorbance-based spectrophotometric quantification system, enabling the assessment of drug loading efficiency. Co-incubation of EVs and chemotherapeutics was sufficient to obtain quantifiable drug loading, and the efficacy of EV loading was drug-dependent. Epirubicin-loaded vesicles showed increased toxicity to bladder cancer cells with respect to the free chemotherapeutic. The cytotoxicity was maintained even upon 6-month storage at -80 °C of loaded EVs.

CONCLUSION

We established an absorbance-based spectrophotometric quantification system that enables a straightforward measure of drug loading efficiency into EVs, and we demonstrated that chemotherapeutic-carrying EVs can be obtained by co-incubation, preserving and increasing drug cytotoxicity.

GFP Farnesylation as a Suitable Strategy for Selectively Tagging Exosomes

Exosomes are small extracellular vesicles (EVs) constituting fully biological, cell-derived nanovesicles with great potential in cell-to-cell communication and drug delivery applications. The current gold standard for EV labeling and tracking is represented by fluorescent lipophilic dyes which, however, importantly lack selectivity, due to their unconditional affinity for lipids. Herein, an alternative EV fluorescent labeling approach is in-depth evaluated, by taking advantage of green fluorescent protein (GFP) farnesylation (GFP-f), a post-translational modification to directly anchor GFP to the EV membrane. The performance of GFP-f is analyzed, in terms of selectivity and efficiency, in several typical EV experimental setups such as delivery in recipient cells, surface engineering, and cargo loading. First, the capability of GFP and GFP-f to label exosomes was compared, showing significantly higher GFP protein levels and fluorescence intensity in GFP-f- than in GFP-labeled exosomes, highlighting the advantage of directly anchoring the GFP to the EV cell membrane. Then, the GFP-f tag was further compared to Vybrant DiD lipophilic dye labeling in exosome uptake studies, by capturing EV intracellular fluorescence in a time- and concentration-dependent manner. The internalization assay revealed a particular ability of GFP-f to monitor the uptake of tagged exosomes into recipient cells, with a significant peak of intensity reached 12 h after administration by GFP-f but not Vybrant-labeled EVs. Finally, the GFP-f labeling capability was challenged in the presence of a surface modification of exosomes and after transfection for siRNA loading. Results showed that both procedures can influence GFP-f performance compared to naïve GFP-f exosomes, although fluorescence is importantly maintained in both cases. Overall, these data provide direct insight into the advantages and limitations of GFP-f as a tagging protein for selectively and accurately tracking the exosome route from isolation to uptake in recipient cells, also in the context of EV bioengineering applications.

Advances of New Extracellular Vesicle Isolation and Detection Technologies in Cancer Diagnosis

Cancer is a global health issue threatening people's lives. Currently, cancer detection methods still have a lot of room for improvement in both efficiency and accuracy. The development and application of new technologies are urgently required for early cancer diagnosis and prognosis. Extracellular vesicles (EVs) are a type of phospholipid bilayer vesicle secreted by cells and play an important role in cancer development and metastasis. These small vesicles participate in cancer information transmission, antigen presentation, angiogenesis, immune response, tumor invasion, and mediate signaling pathways in the tumor microenvironment. Liquid biopsy of EV cargo contents is a fast-developing research area, holding promise for early cancer diagnosis and monitoring cancer progression in real-time. However, current EV detection technologies for clinical translation are still facing many challenges. Recent advancements in developing techniques for EV isolation and detection have made significant progress and are paving the way toward clinical application. Here, the advantages and limitations of traditional EV detection and isolation technologies in cancer diagnosis and prognosis are reviewed. The review also focuses on emerging EV detection and isolation technologies in cancer, discusses the challenges faced by current methods, and explores the perspective of new EV detection techniques for future cancer diagnosis.

Characterization of extracellular vesicles by capillary zone electrophoresis: A novel concept for characterization of a next-generation drug delivery platform

Extracellular vesicles (EVs) are a part of a cell-to-cell communication system of prokaryotic and eukaryotic organisms. Their ability to penetrate biological barriers and to transfer molecules between cells shows their potential as a novel class of drug delivery platform. However, because of the great heterogeneity of EVs and the complexity of biological matrices from which they are typically isolated, reliable quality control procedures need to be established to ensure their safety for medical use. According to current recommendations, quantification of EVs, confirmation of their identity, and purity assessment require the use of several analytical techniques, including particle-size distribution analysis, proteomics, and electron microscopy, making the characterization process demanding. Capillary electrophoresis (CE) has recently emerged as an alternative tool for EV characterization. In this study, the available literature on this novel concept for EV characterization was reviewed. Its performance was critically evaluated and compared with currently used methods. The utility of CE in the quality control of EV-based medicines was discussed.

The proteomic landscape of extracellular vesicles derived from human intervertebral disc cells

Background

Extracellular vesicles (EVs) function as biomarkers and are crucial in cell communication and regulation, with therapeutic potential for intervertebral disc (IVD)-related low back pain (LBP). EV cargo is often affected by tissue health, which may affect the therapeutic potential. There is currently limited knowledge of how the cargo of IVD cell-derived EVs varies with tissue health and how differences in proteomic profile affect the predicted biological functions.

Methods

Our study purified EVs from human IVD cell conditioned media by size-exclusion chromatography. Nanoparticle tracking analysis was conducted to measure EV size and concentration. Transmission electron microscopy and Western blot were performed to examine EV structure and markers. Tandem mass tag-mass spectrometry was conducted to determine protein cargo.

Results

Most EVs were exosomes and intermediate microvesicles with an increasing amount linked to disease progression. Of the proteins detected, 88.6% were shared across the non-degenerate, mildly-degenerate, and degenerate samples. GO and KEGG analyses revealed that cargo from the mildly-degenerate samples was the most distinct, with the proteins in high abundance strongly associated with extracellular matrix (ECM) organization and structure. Shared proteins, highly expressed in the non-degenerate and degenerate samples, showed strong associations with cell adhesion, ECM-receptor interaction, and vesicle-mediated transport, respectively.

Conclusions

Our findings indicate that EVs from IVD cells from tissue with different degrees of degeneration share a majority of the cargo proteins. However, the level of expression differs with degeneration grade. Cargo from the mildly-degenerate samples exhibits the most differences. A better understanding of changes in EV cargo in the degenerative process may provide novel information related to molecular mechanisms underlying IVD degeneration and suggest new potential treatment modalities for IVD-related LBP.

Different storage and freezing protocols for extracellular vesicles: a systematic review

BACKGROUND

Extracellular vesicles (EVs) have been considered promising tools in regenerative medicine. However, the nanoscale properties of EVs make them sensitive to environmental conditions. Optimal storage protocols are crucial for maintaining EV structural, molecular, and functional integrity. This systematic review aimed to gather evidence on the effects of various storage protocols on EV characteristics and integrity.

STRATEGY

A comprehensive search was conducted for original studies investigating the impacts of storage temperature, freezing techniques, freeze-thaw cycles, and stabilizing strategies on EV concentration, size distribution, morphology, cargo content, and bioactivity. Results from 50 included studies were analyzed.

RESULTS

Data indicated that rapid freezing procedures and constant subzero temperatures (optimally - 80 °C) resulted in appropriate EV quantity and cargo preservation. Subjecting EVs to multiple freeze-thaw cycles decreased particle concentrations, RNA content, impaired bioactivity, and increased EV size and aggregation. Electron microscopy revealed vesicle enlargement, and fusion, along with membrane deformation after being exposed to substandard storage protocols. The addition of stabilizers like trehalose helped EVs to maintain integrity. Of note, storage in native biofluids offered improved stability over purified EVs in buffers.

CONCLUSION

Data emphasize the critical need for precise storage protocols for EVs to ensure reproducible research outcomes and clinical applications. Further studies using reliable methods are necessary to create specific guidelines for improving the stability of EVs in various applications.

Extracellular Vesicles Mimetic Design of Membrane Chimeric Nanovesicles for dsRNA Delivery in Spray-Induced Gene Silencing for Crop Protection

Spray-induced gene silencing (SIGS) presents a promising RNA interference (RNAi)-based crop protection strategy against eukaryotic phytopathogens. However, the application of SIGS faces challenges, such as the limited uptake of dsRNA by certain pathogens and the instability of dsRNA in the environment. This study introduces innovative biomimetic nanovesicles, called extracellular vesicle (EV) mimetic chimeric nanovesicles (ECNs), assembled from tomato leaf cell membranes and cationic sterosomes via the freeze-thaw method. Similar to the function of EVs in nucleic acid transport between cells, ECNs serve as a hybrid nanosystem to overcome the challenge of delivering exogenous dsRNA in Phytophthora infestans. When applied to SIGS, the superiority of ECNs in crop protection becomes more apparent, including high loading and protection of dsRNA, improved biosafety, and efficient internalization into pathogen and plant cells, all of which significantly enhance the efficacy of RNAi in preventing early infection of P. infestans to susceptible tomato plants. This study demonstrates that ECNs are promising RNA delivery vehicles and will promote the use of SIGS-based RNA pesticides in sustainable agricultural production.

Advances in plant-derived extracellular vesicles: isolation, composition, and biological functions

Plant-derived extracellular vesicles (PDEVs) are nanoscale vesicles released from plant cells into the extracellular space. While similar in structure and function to mammalian-derived EVs, PDEVs are unique due to their origin and the specific metabolites they carry. PDEVs have gained significant attention in recent years, with numerous reports isolating different PDEVs from various plants, each exhibiting diverse biological functions. However, the field is still in its early stages, and many issues need further exploration. To better develop and utilize PDEVs, it is essential to have a comprehensive understanding of their characteristics. This review provides an overview of recent advances in PDEV research. It focuses on the methods and techniques for isolating and purifying PDEVs, comparing their respective advantages, limitations, and application scenarios. Furthermore, we discuss the latest discoveries regarding the composition of PDEVs, including lipids, proteins, nucleic acids, and various plant metabolites. Additionally, we detail advanced studies on the multiple biological functions of PDEVs. Our goal is to advance our understanding of PDEVs and encourage further exploration in PDEV-based science and technology, offering insights into their potential applications for human health.

Streamlined miRNA loading of surface protein-specific extracellular vesicle subpopulations through electroporation

BACKGROUND

Extracellular vesicles (EVs) have emerged as an exciting tool for targeted delivery of therapeutics for a wide range of diseases. As nano-scale membrane-bound particles derived from living cells, EVs possess inherent capabilities as carriers of biomolecules. However, the translation of EVs into viable therapeutic delivery vehicles is challenged by lengthy and inefficient processes for cargo loading and pre- and post-loading purification of EVs, resulting in limited quantity and consistency of engineered EVs.

RESULTS

In this work, we develop a fast and streamlined method to load surface protein-specific subpopulations of EVs with miRNA by electroporating EVs, while they are bound to antibody-coated beads. We demonstrate the selection of CD81+ EV subpopulation using magnetic microbeads, facilitating rapid EV manipulations, loading, and subsequent purification processes. Our approach shortens the time per post-electroporation EV wash by 20-fold as compared to the gold standard EV washing method, ultracentrifugation, resulting in about 2.5-h less time required to remove unloaded miRNA. In addition, we addressed the challenge of nonspecific binding of cargo molecules due to affinity-based EV selection, lowering the purity of engineered EVs, by implementing innovative strategies, including poly A carrier RNA-mediated blocking and dissociation of residual miRNA and EV-like miRNA aggregates following electroporation.

CONCLUSIONS

Our streamlined method integrates magnetic bead-based selection with electroporation, enabling rapid and efficient loading of miRNA into CD81+ EVs. This approach not only achieves comparable miRNA loading efficiency to conventional bulk electroporation methods but also concentrates CD81+ EVs and allows for simple electroporation parameter adjustment, promising advancements in therapeutic RNA delivery systems with enhanced specificity and reduced toxicity.

Evaluation of extracellular vesicle aggregation by single vesicle analysis

Extracellular vesicles (EVs) play pivotal roles in intercellular communication and are implicated in numerous physiological and pathological processes. Here, we introduce a quantitative technique using total internal reflection fluorescence microscopy (TIRFm)-based single vesicle analysis (SVA) to assess EV aggregation, a critical factor influencing their biological functionality. Employing two-colored fluorescent recombinant EV mixtures, this method enables precise discrimination between aggregated and non-aggregated EVs. It allows for calculating an aggregation ratio from the colocalization of fluorescence signals. We evaluate the impact of isolation methods, storage conditions, and biochemical environments on EV aggregation, including salt and pH variations and the presence of antibodies. Additionally, we quantitatively assess the efficacy of aggregation removal techniques, revealing significant variability in removal methods depending on the type of aggregates. This analytical approach is expected to enhance our understanding of EV aggregation dynamics and set a new standard for the characterization and functional analysis of EVs.

Development of complementary analytical methods to characterize extracellular vesicles

BACKGROUND

Extracellular vesicles (EVs) are involved in intercellular communication and various biological processes. They hold clinical promise for the diagnosis and management of a wide range of pathologies, including cancer, cardiovascular diseases and degenerative diseases, and are of interest as regenerative therapies. Understanding the complex structure of these EVs is essential to perceive the current challenges associated with their analysis and characterization. Today, challenges remain in terms of access to high-yield, high-purity isolation methods, as well as analytical methods for characterizing and controlling the quality of these products for clinical use.

RESULTS

We isolated EVs from the same immortalized human cell culture supernatant using two commonly used approaches, namely differential ultracentrifugation and membrane affinity. Then we evaluated EV morphology, size, zeta potential, particle and protein content, as well as protein identity using cryogenic electron microscopy, nanoparticle tracking analysis, asymmetric field flow fractionation (AF4) and size exclusion chromatography (SEC) coupled to multi angle light scattering, bicinchoninic acid assay, electrophoretic light scattering, western blotting and high-resolution mass spectrometry. Compared to membrane affinity isolation, dUC is a more efficient isolation process for obtaining particles with the characteristics expected for EVs and more specifically for exosomes. To validate an isolation process, cryogenic electron microscopy is essential to confirm vesicles with membranes. High resolution mass spectrometry is powerful for understanding the mechanism of action of vesicles. Separative methods, such as AF4 and SEC, are interesting for separating vesicle subpopulations and contaminants.

SIGNIFICANCE

This study provides a critical assessment of eight different techniques for analyzing EVs, some of which are mandatory for in-depth characterization and deciphering, while others are more appropriate for routine analysis, once the production and isolation process has been validated. The strengths and limitations of the different approaches used are highlighted.

Focusing on exosomes to overcome the existing bottlenecks of CAR-T cell therapy

Since chimeric antigen receptor T (CAR-T) cells were introduced three decades ago, the treatment using these cells has led to outstanding outcomes, and at the moment, CAR-T cell therapy is a well-established mainstay for treating CD19 + malignancies and multiple myeloma. Despite the astonishing results of CAR-T cell therapy in B-cell-derived malignancies, several bottlenecks must be overcome to promote its safety and efficacy and broaden its applicability. These bottlenecks include cumbersome production process, safety concerns of viral vectors, poor efficacy in treating solid tumors, life-threatening side effects, and dysfunctionality of infused CAR-T cells over time. Exosomes are nano-sized vesicles that are secreted by all living cells and play an essential role in cellular crosstalk by bridging between cells. In this review, we discuss how the existing bottlenecks of CAR-T cell therapy can be overcome by focusing on exosomes. First, we delve into the effect of tumor-derived exosomes on the CAR-T cell function and discuss how inhibiting their secretion can enhance the efficacy of CAR-T cell therapy. Afterward, the application of exosomes to the manufacturing of CAR-T cells in a non-viral approach is discussed. We also review the latest advancements in ex vivo activation and cultivation of CAR-T cells using exosomes, as well as the potential of engineered exosomes to in vivo induction or boost the in vivo proliferation of CAR-T cells. Finally, we discuss how CAR-engineered exosomes can be used as a versatile tool for the direct killing of tumor cells or delivering intended therapeutic payloads in a targeted manner.

Mapping bacterial extracellular vesicle research: insights, best practices and knowledge gaps

Bacterial extracellular vesicles (BEVs) enable communication between bacteria and their natural habitats, including multicellular organisms such as humans. Consequently, the study of BEVs has rapidly gained attention with recent research raising the prospect of developing BEVs as biomarkers and treatments to manage (mal)functioning of natural habitats. Although diverse technologies are available, the composition of their source, their heterogeneity in biophysical and biochemical features, and their multifaceted cargo composition challenges the analysis of BEVs. To map current practices in BEV research, we analyzed 845 publications released in 2015-2021, reporting 3338 BEV-related experiments. The extracted data are accessible via the publicly available EV-TRACK knowledgebase ( https://evtrack.org/ ). We identify the need for transparent reporting, delineate knowledge gaps, outline available best practices and define areas in need of guidance to ensure advances in BEV research and accelerate BEV applications.

Comparative Analysis of Extracellular Vesicles from Cytotoxic CD8+ αβ T Cells and γδ T Cells

BACKGROUND

Although belonging to different branches of the immune system, cytotoxic CD8+ αβ T cells and γδ T cells utilize common cytolytic effectors including FasL, granzymes, perforin and granulysin. The effector proteins are stored in different subsets of lysosome-related effector vesicles (LREVs) and released to the immunological synapse upon target cell encounter. Notably, in activated cells, LREVs and potentially other vesicles are continuously produced and released as extracellular vesicles (EVs). Presumably, EVs serve as mediators of intercellular communication in the local microenvironment or at distant sites.

METHODS

EVs of activated and expanded cytotoxic CD8+ αβ T cells or γδ T cells were enriched from culture supernatants by differential and ultracentrifugation and characterized by nanoparticle tracking analyses and Western blotting. For a comparative proteomic profiling, EV preparations from both cell types were isobaric labeled with tandem mass tags (TMT10plex) and subjected to mass spectrometry analysis.

RESULTS

686 proteins were quantified in EV preparations of cytotoxic CD8+ αβ T cells and γδ T cells. Both populations shared a major set of similarly abundant proteins, while much fewer proteins presented higher abundance levels in either CD8+ αβ T cells or γδ T cells. To our knowledge, we provide the first comparative analysis of EVs from cytotoxic CD8+ αβ T cells and γδ T cells.

Human mesenchymal stroma/stem-like cell-derived taxol-loaded EVs/exosomes transfer anti-tumor microRNA signatures and express enhanced SDF-1-mediated tumor tropism

BACKGROUND

The release of extracellular vesicles (EVs) including exosomes from human mesenchymal stroma/stem-like cells (MSC) represents valuable cell-free carriers for the delivery of regenerative and medicinal compounds.

METHODS

EVs/exosomes were isolated by differential centrifugation from four individual MSC as controls and after treatment with a sub-lethal concentration of 10 mM taxol for 24 h, respectively. The isolated EVs/exosomes were characterized and quantified by nano-tracking-analysis and by Western blots. MicroRNAs (miRs) were isolated from the different EVs/exosome populations and expression levels were quantified by qPCR using 1246 miR templates. Cytotoxic effects of the different MSC-derived taxol-loaded EVs/exosomes were determined in five different GFP-transduced cancer cell lines and quantified by a fluoroscan assay with a GFP-detecting fluorimeter. The presence of stroma cell-derived factor 1 (SDF-1) in MSC-derived EVs/exosomes and its enhanced expression in the vesicles after taxol treatment of MSC was quantified by a specific ELISA.

RESULTS

EVs/exosomes isolated from four individual taxol-treated MSC displayed a larger size and higher yields as the control EVs/exosomes and were used as anti-tumor therapeutic vehicles. Application of each of the four MSC-derived taxol-loaded EVs/exosome populations revealed significant cytotoxic effects in cell lines of five different tumor entities (carcinomas of lung, breast, ovar, colon, astrocytoma) in a concentration-dependent manner. Expression analysis of 1246 miRs in these taxol-loaded EVs/exosomes as compared to the corresponding MSC-derived control EVs/exosomes unraveled a taxol-mediated up-regulation of 11 miRs with predominantly anti-tumorigenic properties. Moreover, various constitutively expressed protein levels were unanimously altered in the MSC cultures. Taxol treatment of the different MSC revealed an up-regulation of tetraspanins and a 2.2-fold to 5.4-fold increased expression of SDF-1 among others. Treatment of cancer cells with MSC-derived taxol-loaded EVs/exosomes in the presence of a neutralizing SDF-1 antibody significantly abolished the cytotoxic effects between 20.3% and 27%.

CONCLUSIONS

These findings suggested a taxol-mediated increase of anti-cancer properties in MSC that enhance the tropism of derived EVs/exosomes to tumors, thereby specifically focusing the therapeutic effects of the delivered products.

Extracellular vesicle mimetics as delivery vehicles for oligonucleotide-based therapeutics and plasmid DNA

Introduction

Small membrane particles called extracellular vesicles (EVs) transport biologically active cargo between cells, providing intercellular communication. The clinical application of EVs is limited due to the lack of scalable and cost-effective approaches for their production and purification, as well as effective loading strategies.

Methods

Here we used EV mimetics produced by cell treatment with the actin-destabilizing agent cytochalasin B as an alternative to EVs for the delivery of therapeutic nucleic acids.

Results

Cytochalasin-B-inducible nanovesicles (CINVs) delivered a fully modified N-(methanesulfonyl)- or mesyl (µ-) antisense oligonucleotide to B16 melanoma cells, selectively decreasing the level of target microRNA-21 with effectiveness comparable to that observed upon Lipofectamine 2000-mediated delivery. The efficiency of the CINV-mediated delivery of plasmid DNA encoding EGFP varied depending on the type of recipient cells. Surprisingly, under experimental conditions, CINVs were unable to deliver both modified and natural short RNA duplexes-small interfering RNA and immunostimulatory RNA-probably due to their poor loading into CINVs.

Discussion

CINVs demonstrated unique properties for the delivery of therapeutic nucleic acids, especially for antisense oligonucleotide-based therapy.

Microglia morphological response to mesenchymal stromal cell extracellular vesicles demonstrates EV therapeutic potential for modulating neuroinflammation

BACKGROUND

Mesenchymal stromal cell derived extracellular vesicles (MSC-EVs) are a promising therapeutic for neuroinflammation. MSC-EVs can interact with microglia, the resident immune cells of the brain, to exert their immunomodulatory effects. In response to inflammatory cues, such as cytokines, microglia undergo phenotypic changes indicative of their function e.g. morphology and secretion. However, these changes in response to MSC-EVs are not well understood. Additionally, no disease-relevant screening tools to assess MSC-EV bioactivity exist, which has further impeded clinical translation. Here, we developed a quantitative, high throughput morphological profiling approach to assess the response of microglia to neuroinflammation- relevant signals and whether this morphological response can be used to indicate the bioactivity of MSC-EVs.

RESULTS

Using an immortalized human microglia cell-line, we observed increased size (perimeter, major axis length) and complexity (form factor) upon stimulation with interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α). Upon treatment with MSC-EVs, the overall morphological score (determined using principal component analysis) shifted towards the unstimulated morphology, indicating that MSC-EVs are bioactive and modulate microglia. The morphological effects of MSC-EVs in TNF-α /IFN-γ stimulated cells were concomitant with reduced secretion of 14 chemokines/cytokines (e.g. CXCL6, CXCL9) and increased secretion of 12 chemokines/cytokines (e.g. CXCL8, CXCL10). Proteomic analysis of cell lysates revealed significant increases in 192 proteins (e.g. HIBADH, MEAK7, LAMC1) and decreases in 257 proteins (e.g. PTEN, TOM1, MFF) with MSC-EV treatment. Of note, many of these proteins are involved in regulation of cell morphology and migration. Gene Set Variation Analysis revealed upregulation of pathways associated with immune response, such as regulation of cytokine production, immune cell infiltration (e.g. T cells, NK cells) and morphological changes (e.g. Semaphorin, RHO/Rac signaling). Additionally, changes in microglia mitochondrial morphology were measured suggesting that MSC-EV modulate mitochondrial metabolism.

CONCLUSION

This study comprehensively demonstrates the effects of MSC-EVs on human microglial morphology, cytokine secretion, cellular proteome, and mitochondrial content. Our high-throughput, rapid, low-cost morphometric approach enables screening of MSC-EV batches and manufacturing conditions to enhance EV function and mitigate EV functional heterogeneity in a disease relevant manner. This approach is highly generalizable and can be further adapted and refined based on selection of the disease-relevant signal, target cell, and therapeutic product.

A critical systematic review of extracellular vesicle clinical trials

This systematic review examines the landscape of extracellular vesicle (EV)-related clinical trials to elucidate the field's trends in clinical applications and EV-related methodologies, with an additional focus on the acknowledgement of EV subpopulations. By analysing data from public reporting repositories, we catalogued 471 EV-related clinical trials to date, with indications for over 200 diseases. Diagnostics and companion diagnostics represented the bulk of EV-related clinical trials with cancer being the most frequent application. EV-related therapeutics trials mainly utilized mesenchymal stromal cell (MSC) EVs and were most frequently used for treatment of respiratory illnesses. Ultracentrifugation and RNA-sequencing were the most common isolation and characterization techniques; however, methodology for each was not frequently reported in study records. Most of the reported characterization relied on bulk characterization of EV isolates, with only 11% utilizing EV subpopulations in their experimental design. While this may be connected to a lack of available techniques suitable for clinical implementation, it also highlights the opportunity for use of EV subpopulations to improve translational efforts. As academic research identifies more chemically distinct subpopulations and technologies for their enrichment, we forecast to more refined EV trials in the near future. This review emphasizes the need for meticulous methodological reporting and consideration of EV subpopulations to enhance the translational success of EV-based interventions, pointing towards a paradigm shift in personalized medicine.

Extracellular vesicle-derived biomarkers in prostate cancer care: Opportunities and challenges

Prostate cancer (PCa) is the second most prevalent cancer in men worldwide, presenting a significant global public health challenge that necessitates early detection and personalized treatment. Recently, non-invasive liquid biopsy methods have emerged as promising tools to provide insights into the genetic landscape of PCa and monitor disease progression, aiding decision-making at all stages. Research efforts have concentrated on identifying liquid biopsy biomarkers to improve PCa diagnosis, prognosis, and treatment prediction. This article reviews recent research advances over the last five years utilizing extracellular vesicles (EVs) as a natural biomarker library for PCa, and discusses the clinical translation of EV biomarkers, including ongoing trials and key implementation challenges. The findings underscore the transformative role of liquid biopsy, particularly EV-based biomarkers, in revolutionizing PCa diagnosis, prediction, and treatment.

Stem cell-derived extracellular vesicles: a potential intervention for Bronchopulmonary Dysplasia

Despite advances in neonatal care, the incidence of Bronchopulmonary Dysplasia (BPD) remains high among extreme preterm infants. The pathogenesis of BPD is multifactorial, with inflammation playing a central role. There is strong evidence that stem cell therapy reduces inflammatory changes and restores normal lung morphology in animal models of hyperoxia-induced lung injury. These therapeutic effects occur without significant engraftment of the stem cells in the host lung, suggesting more of a paracrine mechanism mediated by their secretome. In addition, there are multiple concerns with stem cell therapy which may be alleviated by administering only the effective vesicles instead of the cells themselves. Extracellular vesicles (EVs) are cell-derived components secreted by most eukaryotic cells. They can deliver their bioactive cargo (mRNAs, microRNAs, proteins, growth factors) to recipient cells, which makes them a potential therapeutic vehicle in many diseases, including BPD. The following review will highlight recent studies that investigate the effectiveness of EVs derived from stem cells in preventing or repairing injury in the preterm lung, and the potential mechanisms of action that have been proposed. Current limitations will also be discussed as well as suggestions for advancing the field and easing the transition towards clinical translation in evolving or established BPD. IMPACT: Extracellular vesicles (EVs) derived from stem cells are a potential intervention for neonatal lung diseases. Their use might alleviate the safety concerns associated with stem cell therapy. This review highlights recent studies that investigate the effectiveness of stem cell-derived EVs in preclinical models of bronchopulmonary dysplasia. It adds to the existing literature by elaborating on the challenges associated with EV research. It also provides suggestions to advance the field and ease the transition towards clinical applications. Optimizing EV research could ultimately improve the quality of life of extreme preterm infants born at vulnerable stages of lung development.

Immunomodulatory Effects of Probiotic-Derived Extracellular Vesicles: Opportunities and Challenges

Probiotics are known to modulate host immune responses in the course of many diseases. Recently, bacterial extracellular vesicles (EVs), which contain bioactive proteins, lipids, nucleic acids, and metabolites released by bacteria, have been identified as potentially important mediators of bacteria-bacterium and bacteria-host interactions. With the deepening of research, it has been found that probiotic-derived EVs play a significant role in regulating host immune function and, thus, exerting health-promoting effects. Nevertheless, current research is in its early stages, and there remains a long way to go to bridge the gap between basic research and clinical practice. In this review, we describe the fundamental aspects of probiotic-derived EVs, including their biogenesis, cargo sorting mechanism, and transport capabilities. We further discussed the potential mechanisms of probiotic-derived EVs in regulating the host's gut microbiota and immune responses. Finally, we speculate about the potential of probiotic-derived EVs as new postbiotics for applications in functional food, disease treatment substitutes, and immune regulatory adjuvants.

Extracellular vesicles in cancer: challenges and opportunities for clinical laboratories

Extracellular vesicles (EVs) are nano-sized particles secreted by most cells. They transport different types of biomolecules (nucleic acids, proteins, and lipids) characteristic of their tissue or cellular origin that can mediate long-distance intercellular communication. In the case of cancer, EVs participate in tumor progression by modifying the tumor microenvironment, favoring immune tolerance and metastasis development. Consequently, EVs have great potential in liquid biopsy for cancer diagnosis, prognosis and follow-up. In addition, EVs could have a role in cancer treatment as a targeted drug delivery system. The intense research in the EV field has resulted in hundreds of patents and the creation of biomedical companies. However, methodological issues and heterogeneity in EV composition have hampered the advancement of EV validation trials and the development of EV-based diagnostic and therapeutic products. Consequently, only a few EV biomarkers have moved from research to clinical laboratories, such as the ExoDx Prostate IntelliScore (EPI) test, a CLIA/FDA-approved EV prostate cancer diagnostic test. In addition, the number of large-scale multicenter studies that would clearly define biomarker performance is limited. In this review, we will critically describe the different types of EVs, the methods for their enrichment and characterization, and their biological role in cancer. Then, we will specially focus on the parameters to be considered for the translation of EV biology to the clinic laboratory, the advances already made in the field of EVs related to cancer diagnosis and treatment, and the issues still pending to be solved before EVs could be used as a routine tool in oncology.

Dynamics of microRNA secreted via extracellular vesicles during the maturation of embryonic stem cell-derived retinal pigment epithelium

Retinal pigment epithelial (RPE) cells are exclusive to the retina, critically multifunctional in maintaining the visual functions and health of photoreceptors and the retina. Despite their vital functions throughout lifetime, RPE cells lack regenerative capacity, rendering them vulnerable which can lead to degenerative retinal diseases. With advancements in stem cell technology enabling the differentiation of functional cells from pluripotent stem cells and leveraging the robust autocrine and paracrine functions of RPE cells, extracellular vesicles (EVs) secreted by RPE cells hold significant therapeutic potential in supplementing RPE cell activity. While previous research has primarily focused on the trophic factors secreted by RPE cells, there is a lack of studies investigating miRNA, which serves as a master regulator of gene expression. Profiling and defining the functional role of miRNA contained within RPE-secreted EVs is critical as it constitutes a necessary step in identifying the optimal phenotype of the EV-secreting cell and understanding the biological cargo of EVs to develop EV-based therapeutics. In this study, we present a comprehensive profile of miRNA in small extracellular vesicles (sEVs) secreted during RPE maturation following differentiation from human embryonic stem cells (hESCs); early-stage hESC-RPE (20-21 days in culture), mid-stage hESC-RPE (30-31 days in culture) and late-stage hESC-RPE (60-61 days in culture). This exploration is essential for ongoing efforts to develop and optimize EV-based intraocular therapeutics utilizing RPE-secreted EVs, which may significantly impact the function of dysfunctional RPE cells in retinal diseases.

Advances in Extracellular-Vesicles-Based Diagnostic and Therapeutic Approaches for Ocular Diseases

Extracellular vesicles (EVs) are nanoscale membrane vesicles of various sizes that can be secreted by most cells. EVs contain a diverse array of cargo, including RNAs, lipids, proteins, and other molecules with functions of intercellular communication, immune modulation, and regulation of physiological and pathological processes. The biofluids in the eye, including tears, aqueous humor, and vitreous humor, are important sources for EV-based diagnosis of ocular disease. Because the molecular cargos may reflect the biology of their parental cells, EVs in these biofluids, as well as in the blood, have been recognized as promising candidates as biomarkers for early diagnosis of ocular disease. Moreover, EVs have also been used as therapeutics and targeted drug delivery nanocarriers in many ocular disorders because of their low immunogenicity and superior biocompatibility in nature. In this review, we provide an overview of the recent advances in the field of EV-based studies on the diagnosis and therapeutics of ocular disease. We summarized the origins of EVs applied in ocular disease, assessed different methods for EV isolation from ocular biofluid samples, highlighted bioengineering strategies of EVs as drug delivery systems, introduced the latest applications in the diagnosis and treatment of ocular disease, and presented their potential in the current clinical trials. Finally, we briefly discussed the challenges of EV-based studies in ocular disease and some issues of concern for better focusing on clinical translational studies of EVs in the future.

Emerging Trends in the Application of Extracellular Vesicles as Novel Oral Delivery Vehicles for Therapeutics in Inflammatory Diseases

Inflammation involves complex immune responses where cytokines such as TNF-α, IL-1, and IL-6 promote vasodilation and increased vascular permeability to facilitate immune cell migration to inflammation sites. Persistent inflammation is linked to diseases like cancer, arthritis, and neurodegenerative disorders. Although oral anti-inflammatory drugs are favored for their non-invasiveness and cost-effectiveness, their efficacy is often compromised due to gastrointestinal degradation and limited bioavailability. Recent advancements highlight the potential of extracellular vesicles (EVs) as nanocarriers that enhance drug delivery by encapsulating therapeutic agents, ensuring targeted release and reduced toxicity. These EVs, derived from dietary sources and cell cultures, exhibit excellent biocompatibility and stability, presenting a novel approach in anti-inflammatory therapies. This review discusses the classification and advantages of orally administered EVs (O-EVs), their mechanism of action, and their emerging role in treating inflammatory conditions, positioning them as promising vectors in the development of innovative anti-inflammatory drug delivery systems.

Size-Exclusion Chromatography: A Path to Higher Yield and Reproducibility Compared to Sucrose Cushion Ultracentrifugation for Extracellular Vesicle Isolation in Multiple Myeloma

Small extracellular vesicles (EVs) play a pivotal role in intercellular communication across various physiological and pathological contexts. Despite their growing significance as disease biomarkers and therapeutic targets in biomedical research, the lack of reliable isolation techniques remains challenging. This study characterizes vesicles that were isolated from conditioned culture media (CCM) sourced from three myeloma cell lines (MM.1S, ANBL-6, and ALMC-1), and from the plasma of healthy donors and multiple myeloma patients. We compared the efficacy, reproducibility, and specificity of isolating small EVs using sucrose cushion ultracentrifugation (sUC) vs. ultrafiltration combined with size-exclusion chromatography (UF-SEC). Our results demonstrate that UF-SEC emerges as a more practical, efficient, and consistent method for EV isolation, outperforming sUC in the yield of EV recovery and exhibiting lower variability. Additionally, the comparison of EV characteristics among the three myeloma cell lines revealed distinct biomarker profiles. Finally, our results suggest that HBS associated with Tween 20 improves EV recovery and preservation over PBS. Standardization of small EV isolation methods is imperative, and our comparative evaluation represents a significant step toward achieving this goal.

Utilizing extracellular vesicles as a drug delivery system in glaucoma and RGC degeneration

Retinal diseases are the leading cause of blindness, resulting in irreversible degeneration and death of retinal neurons. One such cell type, the retinal ganglion cell (RGC), is responsible for connecting the retina to the rest of the brain through its axons that make up the optic nerve and is the primary cell lost in glaucoma and traumatic optic neuropathy. To date, different therapeutic strategies have been investigated to protect RGCs from death and preserve vision, yet currently available strategies are restricted to treating neuron loss by reducing intraocular pressure. A major barrier identified by these studies is drug delivery to RGCs, which is in large part due to drug stability, short duration time at target, low delivery efficiency, and undesired off-target effects. Therefore, a delivery system to deal with these problems is needed to ensure maximum benefit from the candidate therapeutic material. Extracellular vesicles (EV), nanocarriers released by all cells, are lipid membranes encapsulating RNAs, proteins, and lipids. As they naturally shuttle these encapsulated compounds between cells for communicative purposes, they may be exploitable and offer opportunities to overcome hurdles in retinal drug delivery, including drug stability, drug molecular weight, barriers in the retina, and drug adverse effects. Here, we summarize the potential of an EV drug delivery system, discussing their superiorities and potential application to target RGCs.

Extracellular vesicles may provide an alternative detoxification pathway during skeletal muscle myoblast ageing

Skeletal muscle (SM) acts as a secretory organ, capable of releasing myokines and extracellular vesicles (SM-EVs) that impact myogenesis and homeostasis. While age-related changes have been previously reported in murine SM-EVs, no study has comprehensively profiled SM-EV in human models. To this end, we provide the first comprehensive comparison of SM-EVs from young and old human primary skeletal muscle cells (HPMCs) to map changes associated with SM ageing. HPMCs, isolated from young (24 ± 1.7 years old) and older (69 ± 2.6 years old) participants, were immunomagnetically sorted based on the presence of the myogenic marker CD56 (N-CAM) and cultured as pure (100% CD56+) or mixed populations (MP: 90% CD56+). SM-EVs were isolated using an optimised protocol combining ultrafiltration and size exclusion chromatography (UF + SEC) and their biological content was extensively characterised using Raman spectroscopy (RS) and liquid chromatography mass spectrometry (LC-MS). Minimal variations in basic EV parameters (particle number, size, protein markers) were observed between young and old populations. However, biochemical fingerprinting by RS highlighted increased protein (amide I), lipid (phospholipids and phosphatidylcholine) and hypoxanthine signatures for older SM-EVs. Through LC-MS, we identified 84 shared proteins with functions principally related to cell homeostasis, muscle maintenance and transcriptional regulation. Significantly, SM-EVs from older participants were comparatively enriched in proteins involved in oxidative stress and DNA/RNA mutagenesis, such as E3 ubiquitin-protein ligase TTC3 (TTC3), little elongation complex subunit 1 (ICE1) and Acetyl-CoA carboxylase 1 (ACACA). These data suggest SM-EVs could provide an alternative pathway for homeostasis and detoxification during SM ageing.

Quality control and validation of extracellular vesicles isolated from cultured human breast cancer cells

OBJECTIVE

Extracellular vesicles (EVs) have been shown to play a critical role in promoting tumorigenesis. As EV research grows, it is of importance to have standardization of isolation, quality control, characterization and validation methods across studies along with reliable references to explore troubleshooting solutions. Therefore, our objective with this Research Note was to isolate EVs from multiple breast cancer cell lines and to describe and perform protocols for validation as outlined by the list of minimal information for studies of EVs (MISEV) from the International Society for Extracellular Vesicles.

RESULTS

To isolate EVs, two techniques were employed: ultracentrifugation and size exclusion chromatography. Ultracentrifugation yielded better recovery of EVs in our hands and was therefore used for further validation. In order to satisfy the MISEV requirements, protein quantification, immunoblotting of positive (CD9, CD63, TSG101) and negative (TGFβ1, β-tubulin) markers, nanoflow cytometry and electron microscopy was performed. With these experiments, we demonstrate that yield of validated EVs varied between different breast cancer cell lines. Protocols were optimized to accommodate for low levels of EVs, and various technical and troubleshooting suggestions are included for potential application to other cell types that may provide benefit to investigators interested in future EV studies.

Biofluid, Imaging, Physiological, and Functional Biomarkers of Mild Traumatic Brain Injury and Subconcussive Head Impacts

Post-concussive symptoms are frequently reported by individuals who sustain mild traumatic brain injuries (mTBIs) and subconcussive head impacts, even when evidence of intracranial pathology is lacking. Current strategies used to evaluate head injuries, which primarily rely on self-report, have a limited ability to predict the incidence, severity, and duration of post-concussive symptoms that will develop in an individual patient. In addition, these self-report measures have little association with the underlying mechanisms of pathology that may contribute to persisting symptoms, impeding advancement in precision treatment for TBI. Emerging evidence suggests that biofluid, imaging, physiological, and functional biomarkers associated with mTBI and subconcussive head impacts may address these shortcomings by providing more objective measures of injury severity and underlying pathology. Interest in the use of biomarker data has rapidly accelerated, which is reflected by the recent efforts of organizations such as the National Institute of Neurological Disorders and Stroke and the National Academies of Sciences, Engineering, and Medicine to prioritize the collection of biomarker data during TBI characterization in acute-care settings. Thus, this review aims to describe recent progress in the identification and development of biomarkers of mTBI and subconcussive head impacts and to discuss important considerations for the implementation of these biomarkers in clinical practice.

Microglia Morphological Response to Mesenchymal Stromal Cell Extracellular Vesicles Demonstrates EV Therapeutic Potential for Modulating Neuroinflammation

Background

Mesenchymal stromal cell derived extracellular vesicles (MSC-EVs) are a promising therapeutic for neuroinflammation. MSC-EVs can interact with microglia, the resident immune cells of the brain, to exert their immunomodulatory effects. In response to inflammatory cues, such as cytokines, microglia undergo phenotypic changes indicative of their function e.g. morphology and secretion. However, these changes in response to MSC-EVs are not well understood. Additionally, no disease-relevant screening tools to assess MSC-EV bioactivity exist, which has further impeded clinical translation. Here, we developed a quantitative, high throughput morphological profiling approach to assess the response of microglia to neuroinflammation-relevant signals and whether this morphological response can be used to indicate the bioactivity of MSC-EVs.

Results

Using an immortalized human microglia cell-line, we observed increased size (perimeter, major axis length) and complexity (form factor) upon stimulation with interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α). Upon treatment with MSC-EVs, the overall morphological score (determined using principal component analysis) shifted towards the unstimulated morphology, indicating that MSC-EVs are bioactive and modulate microglia. The morphological effects of MSC-EVs in TNF-γ/IFN-α stimulated cells were concomitant with reduced secretion of 14 chemokines/cytokines (e.g. CXCL6, CXCL9) and increased secretion of 12 chemokines/cytokines (e.g. CXCL8, CXCL10). Proteomic analysis of cell lysates revealed significant increases in 192 proteins (e.g. HIBADH, MEAK7, LAMC1) and decreases in 257 proteins (e.g. PTEN, TOM1, MFF) with MSC-EV treatment. Of note, many of these proteins are involved in regulation of cell morphology and migration. Gene Set Variation Analysis revealed upregulation of pathways associated with immune response, such as regulation of cytokine production, immune cell infiltration (e.g. T cells, NK cells) and morphological changes (e.g. Semaphorin, RHO/Rac signaling). Additionally, changes in microglia mitochondrial morphology were measured suggesting that MSC-EV modulate mitochondrial metabolism.

Conclusion

This study comprehensively demonstrates the effects of MSC-EVs on human microglial morphology, cytokine secretion, cellular proteome, and mitochondrial content. Our high-throughput, rapid, low-cost morphological approach enables screening of MSC-EV batches and manufacturing conditions to enhance EV function and mitigate EV functional heterogeneity in a disease relevant manner. This approach is highly generalizable and can be further adapted and refined based on selection of the disease-relevant signal, target cell, and therapeutic product.

Most recent advances and applications of extracellular vesicles in tackling neurological challenges

Over the past few decades, there has been a notable increase in the global burden of central nervous system (CNS) diseases. Despite advances in technology and therapeutic options, neurological and neurodegenerative disorders persist as significant challenges in treatment and cure. Recently, there has been a remarkable surge of interest in extracellular vesicles (EVs) as pivotal mediators of intercellular communication. As carriers of molecular cargo, EVs demonstrate the ability to traverse the blood-brain barrier, enabling bidirectional communication. As a result, they have garnered attention as potential biomarkers and therapeutic agents, whether in their natural form or after being engineered for use in the CNS. This review article aims to provide a comprehensive introduction to EVs, encompassing various aspects such as their diverse isolation methods, characterization, handling, storage, and different routes for EV administration. Additionally, it underscores the recent advances in their potential applications in neurodegenerative disorder therapeutics. By exploring their unique capabilities, this study sheds light on the promising future of EVs in clinical research. It considers the inherent challenges and limitations of these emerging applications while incorporating the most recent updates in the field.

A new subtype of artificial cell-derived vesicles from dental pulp stem cells with the bioequivalence and higher acquisition efficiency compared to extracellular vesicles

Extracellular vesicles (EVs) derived from dental pulp stem cells (DPSC) have been shown an excellent efficacy in a variety of disease models. However, current production methods fail to meet the needs of clinical treatment. In this study, we present an innovative approach to substantially enhance the production of 'Artificial Cell-Derived Vesicles (ACDVs)' by extracting and purifying the contents released by the DPSC lysate, namely intracellular vesicles. Comparative analysis was performed between ACDVs and those obtained through ultracentrifugation. The ACDVs extracted from the cell lysate meet the general standard of EVs and have similar protein secretion profile. The new ACDVs also significantly promoted wound healing, increased or decreased collagen regeneration, and reduced the production of inflammatory factors as the EVs. More importantly, the extraction efficiency is improved by 16 times compared with the EVs extracted using ultracentrifuge method. With its impressive attributes, this new subtype of ACDVs emerge as a prospective candidate for the future clinical applications in regenerative medicine.

Extracellular vesicle isolation methods identify distinct HIV-1 particles released from chronically infected T-cells

The current study analyzed the intersecting biophysical, biochemical, and functional properties of extracellular particles (EPs) with the human immunodeficiency virus type-1 (HIV-1) beyond the currently accepted size range for HIV-1. We isolated five fractions (Frac-A through Frac-E) from HIV-infected cells by sequential differential ultracentrifugation (DUC). All fractions showed a heterogeneous size distribution with median particle sizes greater than 100 nm for Frac-A through Frac-D but not for Frac-E, which contained small EPs with an average size well below 50 nm. Synchronized and released cultures contained large infectious EPs in Frac-A, with markers of amphisomes and viral components. Additionally, Frac-E uniquely contained EPs positive for CD63, HSP70, and HIV-1 proteins. Despite its small average size, Frac-E contained membrane-protected viral integrase, detectable only after SDS treatment, indicating that it is enclosed in vesicles. Single particle analysis with dSTORM further supported these findings as CD63, HIV-1 integrase, and the viral surface envelope (Env) glycoprotein (gp) colocalized on the same Frac-E particles. Surprisingly, Frac-E EPs were infectious, and infectivity was significantly reduced by immunodepleting Frac-E with anti-CD63, indicating the presence of this protein on the surface of infectious small EPs in Frac-E. To our knowledge, this is the first time that extracellular vesicle (EV) isolation methods have identified infectious small HIV-1 particles (smHIV-1) that are under 50 nm. Collectively, our data indicate that the crossroads between EPs and HIV-1 potentially extend beyond the currently accepted biophysical properties of HIV-1, which may have further implications for viral pathogenesis.

Extracellular Vesicle Spherical Nucleic Acids

Extracellular vesicles (EVs) are naturally occurring vesicles secreted by cells that can transport cargo between cells, making them promising bioactive nanomaterials. However, due to the complex and heterogeneous biological characteristics, a method for robust EV manipulation and efficient EV delivery is still lacking. Here, we developed a novel class of extracellular vesicle spherical nucleic acid (EV-SNA) nanostructures with scalability, programmability, and efficient cellular delivery. EV-SNA was constructed through the simple hydrophobic coassembly of natural EVs with cholesterol-modified oligonucleotides and can be stable for 1 month at room temperature. Based on programmable nucleic acid shells, EV-SNA can respond to AND logic gates to achieve vesicle assembly manipulation. Importantly, EV-SNA can be constructed from a wide range of biological sources EV, enhancing cellular delivery capability by nearly 10-20 times. Compared to artificial liposomal SNA, endogenous EV-SNA exhibited better biocompatibility and more effective delivery of antisense oligonucleotides in hard-to-transfect primary stem cells. Additionally, EV-SNA can deliver functional EVs for immune regulation. As a novel material form, EV-SNA may provide a modular and programmable framework paradigm for EV-based applications in drug delivery, disease treatment, nanovaccines, and other fields.

Biological Activities of Citrus-Derived Extracellular Vesicles on Human Cells: The Role of Preservation

Extracellular vesicles (EVs) have been identified as important mediators for cell-to-cell communication. Citrus-based EVs in particular offer an excellent platform for nutraceutical delivery systems, as their endemic cargo includes micronutrients (e.g., ascorbic acid), which contribute to their antioxidant capacity. Despite being extensively investigated as to their therapeutic and diagnostic potential, their cargo is inherently unstable and thus directly affected by their storage and preservation. In this study, EVs were isolated from citrus fruit using tangential flow filtration and evaluated for their physicochemical characteristics, antioxidant activity and effects on human cells. To assess how their isolation and preservation methods affect these properties, the EVs were tested immediately after isolation (from fresh and freeze-thawed juices) or following freeze-drying. A measurable biological effect of cryoprotection on citrus-derived EVs was evident, whether during or after isolation. This was more pronounced in the cell-based assays, ranging from -4% to +32% in human skin fibroblast proliferation. Nevertheless, the effects on human cancer cells varied depending on the cell line. Although these results should be considered preliminary observations, subject to further investigation, it is safe to state that any type of preservation is expected to impact the EVs' biological activity.

Macromolecules with predominant β-pleated sheet proteins in extracellular vesicles released from Raphanus sativus L. var. caudatus Alef microgreens induce DNA damage-mediated apoptosis in HCT116 colon cancer cells

Plant-derived bioactive macromolecules (i.e., proteins, lipids, and nucleic acids) were prepared as extracellular vesicles (EVs). Plant-derived EVs are gaining pharmaceutical research interest because of their bioactive components and delivery properties. The spherical nanosized EVs derived from Raphanus sativus L. var. caudatus Alef microgreens previously showed antiproliferative activity in HCT116 colon cancer cells from macromolecular compositions (predominantly proteins). To understand the mechanism of action, the biological activity studies, i.e., antiproliferation, cellular biochemical changes, DNA conformational changes, DNA damage, apoptotic nuclear morphological changes, apoptosis induction, and apoptotic pathways, were determined by neutral red uptake assay, synchrotron radiation-based Fourier transform infrared microspectroscopy, circular dichroism spectroscopy, comet assay, 4',6-diamidino-2-phenylindole (DAPI) staining, flow cytometry, and caspase activity assay, respectively. EVs inhibited HCT116 cell growth in concentration- and time-dependent manners, with a half-maximal inhibitory concentration of 675.4 ± 33.8 μg/ml at 48 h and a selectivity index of 1.5 ± 0.076. HCT116 treated with EVs mainly changed the cellular biochemical compositions in the nucleic acids and carbohydrates region. The DNA damage caused no changes in DNA conformation. The apoptotic nuclear morphological changes were associated with the increased apoptotic cell population. The apoptotic cell death was induced by both extrinsic and intrinsic pathways. EVs have potential as antiproliferative bioparticles.

Stem cell-derived extracellular vesicles in the therapeutic intervention of Alzheimer's Disease, Parkinson's Disease, and stroke

With the increase in the aging population, the occurrence of neurological disorders is rising. Recently, stem cell therapy has garnered attention due to its convenient sourcing, minimal invasiveness, and capacity for directed differentiation. However, there are some disadvantages, such as poor quality control, safety assessments, and ethical and logistical issues. Consequently, scientists have started to shift their attention from stem cells to extracellular vesicles due to their similar structures and properties. Beyond these parallels, extracellular vesicles can enhance biocompatibility, facilitate easy traversal of barriers, and minimize side effects. Furthermore, stem cell-derived extracellular vesicles can be engineered to load drugs and modify surfaces to enhance treatment outcomes. In this review, we summarize the functions of native stem cell-derived extracellular vesicles, subsequently review the strategies for the engineering of stem cell-derived extracellular vesicles and their applications in Alzheimer's disease, Parkinson's disease, and stroke, and discuss the challenges and solutions associated with the clinical translation of stem cell-derived extracellular vesicles.

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.

Development of a Sampling and Storage Protocol of Extracellular Vesicles (EVs)-Establishment of the First EV Biobank for Polytraumatized Patients

In the last few years, several studies have emphasized the existence of injury-specific EV "barcodes" that could have significant importance for the precise diagnosis of different organ injuries in polytrauma patients. To expand the research potential of the NTF (network trauma research) biobank of polytraumatized patients, the NTF research group decided to further establish a biobank for EVs. However, until now, the protocols for the isolation, characterization, and storage of EVs for biobank purposes have not been conceptualized. Plasma and serum samples from healthy volunteers (n = 10) were used. Three EV isolation methods of high relevance for the work with patients' samples (ultracentrifugation, size exclusion chromatography, and immune magnetic bead-based isolation) were compared. EVs were quantified using nanoparticle tracking analysis, EV proteins, and miRNAs. The effects of different isolation solutions; the long storage of samples (up to 3 years); and the sensibility of EVs to serial freezing-thawing cycles and different storage conditions (RT, 4/-20/-80 °C, dry ice) were evaluated. The SEC isolation method was considered the most suitable for EV biobanking. We did not find any difference in the quantity of EVs between serum and plasma-EVs. The importance of particle-free PBS as an isolation solution was confirmed. Plasma that has been frozen for a long time can also be used as a source of EVs. Serial freezing-thawing cycles were found to affect the mean size of EVs but not their amount. The storage of EV samples for 5 days on dry ice significantly reduced the EV protein concentration.

Mesenchymal stromal cell-derived extracellular vesicles therapy openings new translational challenges in immunomodulating acute liver inflammation

Inflammation plays a critical role in conditions such as acute liver failure, acute-on-chronic liver failure, and ischemia-reperfusion-induced liver injury. Various pathogenic pathways contribute to liver inflammation, involving inflammatory polarization of macrophages and Küpffer cells, neutrophil infiltration, dysregulation of T cell subsets, oxidative stress, and activation of hepatic stellate cells. While mesenchymal stromal cells (MSCs) have demonstrated beneficial properties, their clinical translation is limited by their cellular nature. However, MSC-derived extracellular vesicles (MSC-EVs) have emerged as a promising cell-free therapeutic approach for immunomodulation. MSC-EVs naturally mirror their parental cell properties, overcoming the limitations associated with the use of MSCs. In vitro and in vivo preclinical studies have demonstrated that MSC-EVs replicate the beneficial effects of MSCs in liver injury. This includes the reduction of cell death and oxidative stress, improvement of hepatocyte function, induction of immunomodulatory effects, and mitigation of cytokine storm. Nevertheless, MSC-EVs face challenges regarding the necessity of defining consistent isolation methods, optimizing MSCs culture conditions, and establishing quality control measures for EV characterization and functional assessment. By establishing standardized protocols, guidelines, and affordable cost mass production, clinicians and researchers will have a solid foundation to conduct further studies, validate the therapeutic efficacy of MSC-EVs, and ultimately pave the way for their clinical implementation in acute liver injury.