Microfluidic fabrication of cell-derived nanovesicles as endogenous RNA carriers

Advances in preparation and engineering of plant-derived extracellular vesicles for nutrition intervention

Plant-derived extracellular vesicles (PLEVs), as a type of naturally occurring lipid bilayer membrane structure, represent an emerging delivery vehicle with immense potential due to their ability to encapsulate hydrophobic and hydrophilic compounds, shield them from external environmental stresses, control release, exhibit biocompatibility, and demonstrate biodegradability. This comprehensive review analyzes engineering preparation strategies for natural vesicles, focusing on PLEVs and their purification and surface engineering. Furthermore, it encompasses the latest advancements in utilizing PLEVs to transport active components, serving as a nanotherapeutic system. The prospects and potential development of PLEVs are also discussed. It is anticipated that this work will not only address existing knowledge gaps concerning PLEVs but also provide valuable guidance for researchers in the fields of food science and biomedical studies, stimulating novel breakthroughs in plant-based therapeutic options.

High-yield nanovesicles extruded from dental follicle stem cells promote the regeneration of periodontal tissues as an alternative of exosomes

AIM

To identify an optimized strategy for the large-scale production of nanovesicles (NVs) that preserve the biological properties of exosomes (EXOs) for use in periodontal regeneration.

MATERIALS AND METHODS

NVs from dental follicle stem cells (DFSCs) were prepared through extrusion, and EXOs from DFSCs were isolated. The yield of both extruded NVs (eNVs) and EXOs were quantified through protein concentration and particle number analyses. Their pro-migration, pro-proliferation and pro-osteogenesis capacities were compared subsequently in vitro. Additionally, proteomics analysis was conducted. To further evaluate the periodontal regeneration potential of eNVs and EXOs, they were incorporated into collagen sponges and transplanted into periodontal defects in rats. In vivo imaging and H&E staining were utilized to verify their biodistribution and safety. Micro-Computed Tomography analysis and histological staining were performed to examine the regeneration of periodontal tissues.

RESULTS

The yield of eNVs was nearly 40 times higher than that of EXOs. Interestingly, in vitro experiments indicated that the pro-migration and pro-proliferation abilities of eNVs were superior, and the pro-osteogenesis potential was comparable to EXOs. More importantly, eNVs exhibited periodontal regenerative potential similar to that of EXOs.

CONCLUSIONS

Extrusion has proven to be an efficient method for generating numerous eNVs with the potential to replace EXOs in periodontal regeneration.

Synergistic large segmental bone repair by 3D printed bionic scaffolds and engineered ADSC nanovesicles: Towards an optimized regenerative microenvironment

Achieving sufficient bone regeneration in large segmental defects is challenging, with the structure of bone repair scaffolds and their loaded bioactive substances crucial for modulating the local osteogenic microenvironment. This study utilized digital laser processing (DLP)-based 3D printing technology to successfully fabricate high-precision methacryloylated polycaprolactone (PCLMA) bionic bone scaffold structures. Adipose-derived stem cell-engineered nanovesicles (ADSC-ENs) were uniformly and stably modified onto the bionic scaffold surface using a perfusion device, constructing a conducive microenvironment for tissue regeneration and long bone defect repair through the scaffold's structural design and the vesicles' biological functions. Scanning electron microscopy (SEM) examination of the scaffold surface confirmed the efficient loading of ADSC-ENs. The material group loaded with vesicles (PCLMA-BAS-ENs) demonstrated good cell compatibility and osteogenic potential when analyzed for the adhesion and osteogenesis of primary rabbit bone marrow mesenchymal stem cells (BMSCs) on the material surface. Tested in a 15 mm critical rabbit radial defect model, the PCLMA-BAS-ENs scaffold facilitated near-complete bone defect repair after 12 weeks. Immunofluorescence and proteomic results indicated that the PCLMA-BAS-ENs scaffold significantly improved the osteogenic microenvironment at the defect site in vivo, promoted angiogenesis, and enhanced the polarization of macrophages towards M2 phenotype, and facilitated the recruitment of BMSCs. Thus, the PCLMA-BAS-ENs scaffold was proven to significantly promote the repair of large segmental bone defects. Overall, this strategy of combining engineered vesicles with highly biomimetic scaffolds to promote large-segment bone tissue regeneration holds great potential in orthopedic and other regenerative medicine applications.

Engineered nanovesicles from activated neutrophils with enriched bactericidal proteins have molecular debridement ability and promote infectious wound healing

Background

Bacterial infections pose a considerable threat to skin wounds, particularly in the case of challenging-to-treat diabetic wounds. Systemic antibiotics often struggle to penetrate deep wound tissues and topically applied antibiotics may lead to sensitization, necessitating the development of novel approaches for effectively treating germs in deep wound tissues. Neutrophils, the predominant immune cells in the bloodstream, rapidly release an abundance of molecules via degranulation upon activation, which possess the ability to directly eliminate pathogens. This study was designed to develop novel neutrophil cell engineered nanovesicles (NVs) with high production and explore their bactericidal properties and application in promoting infectious wound healing.

Methods

Neutrophils were isolated from peripheral blood and activated in vitro via phorbol myristate acetate (PMA) stimulation. Engineered NVs were prepared by sequentially extruding activated neutrophils followed by ultracentrifugation and were compared with neutrophil-derived exosomes in terms of morphology, size distribution and protein contents. The bactericidal effect of NVs in vitro was evaluated using the spread plate technique, LIVE/DEAD backlight bacteria assay and observation of bacterial morphology. The therapeutic effects of NVs in vivo were evaluated using wound contraction area measurements, histopathological examinations, assessments of inflammatory factors and immunochemical staining.

Results

Activated neutrophils stimulated with PMA in vitro promptly release a substantial amount of bactericidal proteins. NVs are similar to exosomes in terms of morphology and particle size, but they exhibit a significantly higher enrichment of bactericidal proteins. In vitro, NVs demonstrated a significant bactericidal effect, presumably mediated by the enrichment of bactericidal proteins such as lysozyme. These NVs significantly accelerated wound healing, leading to a marked reduction in bacterial load, downregulation of inflammatory factors and enhanced collagen deposition in a full-thickness infectious skin defect model.

Conclusions

We developed engineered NVs derived from activated neutrophils to serve as a novel debridement method targeting bacteria in deep tissues, ultimately promoting infectious wound healing.

Microfluidics-Prepared Ultra-small Biomimetic Nanovesicles for Brain Tumor Targeting

Blood-brain-barrier (BBB) serves as a fatal guard of the central nervous system as well as a formidable obstacle for the treatment of brain diseases such as brain tumors. Cell membrane-derived nanomedicines are promising drug carriers to achieve BBB-penetrating and brain lesion targeting. However, the challenge of precise size control of such nanomedicines has severely limited their therapeutic effect and clinical application in brain diseases. To address this problem, this work develops a microfluidic mixing platform that enables the fabrication of cell membrane-derived nanovesicles with precise controllability and tunability in particle size and component. Sub-100 nm macrophage plasma membrane-derived vesicles as small as 51 nm (nanoscale macrophage vesicles, NMVs), with a narrow size distribution (polydispersity index, PDI: 0.27) and a high drug loading rate (up to 89% for indocyanine green-loaded NMVs, NMVs@ICG (ICG is indocyanine green)), are achieved through a one-step process. Compared to beyond-100 nm macrophage cell membrane vesicles (general macrophage vesicles, GMVs) prepared via the traditional methods, the new NMVs exhibits rapid (within 1 h post-injection) and enhanced orthotopic glioma targeting (up to 78% enhancement), with no extra surface modification. This work demonstrates the great potential of such real-nanoscale cell membrane-derived nanomedicines in targeted brain tumor theranostics.

Preparation of genetically or chemically engineered exosomes and their therapeutic effects in bone regeneration and anti-inflammation

The treatment of bone or cartilage damage and inflammation-related diseases has been a long-standing research hotspot. Traditional treatments such as surgery and cell therapy have only displayed limited efficacy because they can't avoid potential deterioration and ensure cell activity. Recently, exosomes have become a favorable tool for various tissue reconstruction due to their abundant content of proteins, lipids, DNA, RNA and other substances, which can promote bone regeneration through osteogenesis, angiogenesis and inflammation modulation. Besides, exosomes are also promising delivery systems because of stability in the bloodstream, immune stealth capacity, intrinsic cell-targeting property and outstanding intracellular communication. Despite having great potential in therapeutic delivery, exosomes still show some limitations in clinical studies, such as inefficient targeting ability, low yield and unsatisfactory therapeutic effects. In order to overcome the shortcomings, increasing studies have prepared genetically or chemically engineered exosomes to improve their properties. This review focuses on different methods of preparing genetically or chemically engineered exosomes and the therapeutic effects of engineering exosomes in bone regeneration and anti-inflammation, thereby providing some references for future applications of engineering exosomes.

Co-culture engineering: a promising strategy for production of engineered extracellular vesicle for osteoarthritis treatment

The therapeutic effects of extracellular vesicles (EVs) have been identified as a significant factor in intercellular communication in different disease treatments, including osteoarthritis (OA). Compared to the conventional approaches in treating OA, EV therapy is a non-invasive and cell-free method. However, improving the yield of EVs and their therapeutic effects are the main challenges for clinical applications. In this regard, researchers are using the EV engineering potential to overcome these challenges. New findings suggest that the co-culture strategy as an indirect EV engineering method efficiently increases EV production and quality. The co-culture of mesenchymal stem cells (MSCs) and chondrocytes has improved their chondrogenesis, anti-inflammatory effects, and regenerative properties which are mediated by EVs. Hence, co-culture engineering by considerable systems could be useful in producing engineered EVs for different therapeutic applications. Here, we review various co-culture approaches, including diverse direct and indirect, 2D and 3D cell cultures, as well as static and dynamic systems. Meanwhile, we suggest and discuss the advantages of combined strategies to achieve engineered EVs for OA treatment.

Engineering of Cell Derived-Nanovesicle as an Alternative to Exosome Therapy

BACKGROUND

Exosomes, nano-sized vesicles ranging between 30 and 150 nm secreted by human cells, play a pivotal role in long-range intercellular communication and have attracted significant attention in the field of regenerative medicine. Nevertheless, their limited productivity and cost-effectiveness pose challenges for clinical applications. These issues have recently been addressed by cell-derived nanovesicles (CDNs), which are physically synthesized exosome-mimetic nanovesicles from parent cells, as a promising alternative to exosomes. CDNs exhibit structural, physical, and biological properties similar to exosomes, containing intracellular protein and genetic components encapsulated by the cell plasma membrane. These characteristics allow CDNs to be used as regenerative medicine and therapeutics on their own, or as a drug delivery system.

METHODS

The paper reviews diverse methods for CDN synthesis, current analysis techniques, and presents engineering strategies to improve lesion targeting efficiency and/or therapeutic efficacy.

RESULTS

CDNs, with their properties similar to those of exosomes, offer a cost-effective and highly productive alternative due to their non-living biomaterial nature, nano-size, and readiness for use, allowing them to overcome several limitations of conventional cell therapy methods.

CONCLUSION

Ongoing research and enhancement of CDNs engineering, along with comprehensive safety assessments and stability analysis, exhibit vast potential to advance regenerative medicine by enabling the development of efficient therapeutic interventions.

The role of microfluidics and 3D-bioprinting in the future of exosome therapy

Exosome-based strategies constitute a promising tool for therapeutics, avoiding potential immunogenic and tumorigenic side-effects of cell therapies. However, the collection of a suitable exosome pool, and the need for high doses with conventional administration approaches, hamper their clinical translation. To overcome these challenges, versatile exosome collection strategies together with advanced delivery platforms may represent major progress in this field. Microfluidics enables large-scale gathering of both natural and synthetic exosomes for their implementation into bioinks, while 3D-bioprinting holds great promise in regenerative medicine with the use of exosome-loaded scaffolds that mimic the target tissue with controlled pharmacokinetics and pharmacodynamics. Hence, the combination of both strategies might become the key for the translation of exosome therapies to clinical practice.

Engineered exosomes-based theranostic strategy for tumor metastasis and recurrence

Metastasis-associated processes are the predominant instigator of fatalities linked to cancer, wherein the pivotal role of circulating tumor cells lies in the resurgence of malignant growth. In recent epochs, exosomes, constituents of the extracellular vesicle cohort, have garnered attention within the field of tumor theranostics owing to their inherent attributes encompassing biocompatibility, modifiability, payload capacity, stability, and therapeutic suitability. Nonetheless, the rudimentary functionalities and limited efficacy of unmodified exosomes curtail their prospective utility. In an effort to surmount these shortcomings, intricate methodologies amalgamating nanotechnology with genetic manipulation, chemotherapy, immunotherapy, and optical intervention present themselves as enhanced avenues to surveil and intercede in tumor metastasis and relapse. This review delves into the manifold techniques currently employed to engineer exosomes, with a specific focus on elucidating the interplay between exosomes and the metastatic cascade, alongside the implementation of tailored exosomes in abating tumor metastasis and recurrence. This review not only advances comprehension of the evolving landscape within this domain but also steers the trajectory of forthcoming investigations.

Engineering Cell-Derived Nanovesicles for Targeted Immunomodulation

Extracellular vesicles (EVs) show promise for targeted drug delivery but face production challenges with low yields. Cell-derived nanovesicles (CDNVs) made by reconstituting cell membranes could serve as EV substitutes. In this study, CDNVs were generated from mesenchymal stem cells by extrusion. Their proteomic composition, in vitro and in vivo toxicity, and capacity for loading RNA or proteins were assessed. Compared with EVs, CDNVs were produced at higher yields, were comprised of a broader range of proteins, and showed no detrimental effects on cell proliferation, DNA damage, or nitric oxide production in vitro or on developmental toxicity in vivo. CDNVs could be efficiently loaded with RNA and engineered to modify surface proteins. The feasibility of generating immunomodulatory CDNVs was demonstrated by preparing CDNVs with enhanced surface expression of PD1, which could bind to PD-L1 expressing tumor cells, enhance NK and T cell degranulation, and increase immune-mediated tumor cell death. These findings demonstrate the adaptability and therapeutic promise of CDNVs as promising substitutes for natural EVs that can be engineered to enhance immunomodulation.

Engineered extracellular vesicles in female reproductive disorders

Biologically active and nanoscale extracellular vesicles (EVs) participate in a variety of cellular physiological and pathological processes in a cell-free manner. Unlike cells, EVs not only do not cause acute immune rejection, but are much smaller and have a low risk of tumorigenicity or embolization. Because of their unique advantages, EVs show promise in applications in the diagnosis and treatment of reproductive disorders. As research broadens, engineering strategies for EVs have been developed, and engineering strategies for EVs have substantially improved their application potential while circumventing the defects of natural EVs, driving EVs toward clinical applications. In this paper, we will review the engineering strategies of EVs, as well as their regulatory effects and mechanisms on reproductive disorders (including premature ovarian insufficiency (POI), polycystic ovarian syndrome (PCOS), recurrent spontaneous abortion (RSA), intrauterine adhesion (IUA), and endometriosis (EMS)) and their application prospects. This work provides new ideas for the treatment of female reproductive disorders by engineering EVs.

Programming assembly of biomimetic exosomes: An emerging theranostic nanomedicine platform

Exosomes have emerged as a promising cell-free therapeutic approach. However, challenges in large-scale production, quality control, and heterogeneity must be overcome before they can be used clinically. Biomimetic exosomes containing key components of natural exosomes have been assembled through extrusion, artificial synthesis, and liposome fusion to address these limitations. These exosome-mimetics (EMs) possess similar morphology and function but provide higher yields, faster large-scale production, and similar size compared to conventional exosomes. This article provides an overview of the chemical and biological properties of various synthetic exosome systems, including nanovesicles (NVs), EMs, and hybrid exosomes. We highlight recent advances in the production and applications of nanobiotechnology and discuss the advantages, limitations, and potential clinical applications of programming assembly of exosome mimetics.

Plant and mammalian-derived extracellular vesicles: a new therapeutic approach for the future

Background: In recent years, extracellular vesicles have been recognized as important mediators of intercellular communication through the transfer of active biomolecules (proteins, lipids, and nucleic acids) across the plant and animal kingdoms and have considerable roles in several physiological and pathological mechanisms, showing great promise as new therapeutic strategies for a variety of pathologies. Methods: In this study, we carefully reviewed the numerous articles published over the last few decades on the general knowledge of extracellular vesicles, their application in the therapy of various pathologies, and their prospects as an approach for the future. Results: The recent discovery and characterization of extracellular vesicles (EVs) of diverse origins and biogenesis have altered the current paradigm of intercellular communication, opening up new diagnostic and therapeutic perspectives. Research into these EVs released by plant and mammalian cells has revealed their involvement in a number of physiological and pathological mechanisms, such as embryonic development, immune response, tissue regeneration, and cancer. They are also being studied as potential biomarkers for disease diagnosis and vectors for drug delivery. Conclusion: Nanovesicles represent powerful tools for intercellular communication and the transfer of bioactive molecules. Their molecular composition and functions can vary according to their origin (plant and mammalian), so their formation, composition, and biological roles open the way to therapeutic applications in a variety of pathologies, which is arousing growing interest in the scientific community. Clinical Trial Registration: ClinicalTrials.gov identifier: NCT03608631.

Microfluidic approaches for producing lipid-based nanoparticles for drug delivery applications

The importance of drug delivery for disease treatment is supported by a vast literature and increasing ongoing clinical studies. Several categories of nano-based drug delivery systems have been considered in recent years, among which lipid-based nanomedicines, both artificial and cell-derived, remain the most approved. The best artificial systems in terms of biocompatibility and low toxicity are liposomes, as they are composed of phospholipids and cholesterol, the main components of cell membranes. Extracellular vesicles-biological nanoparticles released from cells-while resembling liposomes in size, shape, and structure, have a more complex composition with up to hundreds of different types of lipids, proteins, and carbohydrates in their membranes, as well as an internal cargo. Although nanoparticle technologies have revolutionized drug delivery by enabling passive and active targeting, increased stability, improved solubilization capacity, and reduced dose and adverse effects, the clinical translation remains challenging due to manufacturing limitations such as laborious and time-consuming procedures and high batch-to-batch variability. A sea change occurred when microfluidic strategies were employed, offering advantages in terms of precise particle handling, simplified workflows, higher sensitivity and specificity, and good reproducibility and stability over bulk methods. This review examines scientific advances in the microfluidics-mediated production of lipid-based nanoparticles for therapeutic applications. We will discuss the preparation of liposomes using both hydrodynamic focusing of microfluidic flow and mixing by herringbone and staggered baffle micromixers. Then, an overview on microfluidic approaches for producing extracellular vesicles and extracellular vesicles-mimetics for therapeutic applications will describe microfluidic extrusion, surface engineering, sonication, electroporation, nanoporation, and mixing. Finally, we will outline the challenges, opportunities, and future directions of microfluidic investigation of lipid-based nanoparticles in the clinic.

Cell mediated ECM-degradation as an emerging tool for anti-fibrotic strategy

Investigation into the role of cells with respect to extracellular matrix (ECM) remodeling is still in its infancy. Particularly, ECM degradation is an indispensable process during the recovery from fibrosis. Cells with ECM degradation ability due to the secretion of various matrix metalloproteinases (MMPs) have emerged as novel contributors to the treatment of fibrotic diseases. In this review, we focus on the ECM degradation ability of cells associated with the repertoire of MMPs that facilitate the attenuation of fibrosis through the inhibition of ECM deposition. Besides, innovative approaches to engineering and characterizing cells with degradation ability, as well as elucidating the mechanism of the ECM degradation, are also illustrated. Studies conducted to date on the use of cell-based degradation for therapeutic purposes to combat fibrosis are summarized. Finally, we discuss the therapeutic potential of cells with high degradation ability, hoping to bridge the gap between benchside research and bedside applications in treating fibrotic diseases.

Strategies for Engineering of Extracellular Vesicles

Extracellular vesicles (EVs) are membrane vesicles released by cells into the extracellular space. EVs mediate cell-to-cell communication through local and systemic transportation of biomolecules such as DNA, RNA, transcription factors, cytokines, chemokines, enzymes, lipids, and organelles within the human body. EVs gained a particular interest from cancer biology scientists because of their role in the modulation of the tumor microenvironment through delivering bioactive molecules. In this respect, EVs represent an attractive therapeutic target and a means for drug delivery. The advantages of EVs include their biocompatibility, small size, and low immunogenicity. However, there are several limitations that restrict the widespread use of EVs in therapy, namely, their low specificity and payload capacity. Thus, in order to enhance the therapeutic efficacy and delivery specificity, the surface and composition of extracellular vesicles should be modified accordingly. In this review, we describe various approaches to engineering EVs, and further discuss their advantages and disadvantages to promote the application of EVs in clinical practice.

Tailoring the Inherent Properties of Biobased Nanoparticles for Nanomedicine

Biobased nanoparticles are at the leading edge of the rapidly developing field of nanomedicine and biotherapeutics. Their unique size, shape, and biophysical properties make them attractive tools for biomedical research, including vaccination, targeted drug delivery, and immune therapy. These nanoparticles are engineered to present native cell receptors and proteins on their surfaces, providing a biomimicking camouflage for therapeutic cargo to evade rapid degradation, immune rejection, inflammation, and clearance. Despite showing promising clinical relevance, commercial implementation of these biobased nanoparticles is yet to be fully realized. In this perspective, we discuss advanced biobased nanoparticle designs used in medical applications, such as cell membrane nanoparticles, exosomes, and synthetic lipid-derived nanoparticles, and highlight their benefits and potential challenges. Moreover, we critically assess the future of preparing such particles using artificial intelligence and machine learning. These advanced computational tools will be able to predict the functional composition and behavior of the proteins and cell receptors present on the nanoparticle surfaces. With more advancement in designing new biobased nanoparticles, this field of research could play a key role in dictating the future rational design of drug transporters, thereby ultimately improving overall therapeutic outcomes.

Intrathecal Injection of Autologous Mesenchymal Stem-Cell-Derived Extracellular Vesicles in Spinal Cord Injury: A Feasibility Study in Pigs

Spinal cord injury (SCI) remains one of the current medical and social problems, as it causes deep disability in patients. The use of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) is one strategy for stimulating the post-traumatic recovery of the structure and function of the spinal cord. Here, we chose an optimal method for obtaining cytochalasin B-induced EVs, including steps with active vortex mixing for 60 s and subsequent filtration to remove nuclei and disorganized inclusions. The therapeutic potential of repeated intrathecal injection of autologous MSC-derived EVs in the subacute period of pig contused SCI was also evaluated for the first time. In this study, we observed the partial restoration of locomotor activity by stimulating the remyelination of axons and timely reperfusion of nervous tissue.

Bioengineered exosomal-membrane-camouflaged abiotic nanocarriers: neurodegenerative diseases, tissue engineering and regenerative medicine

A bio-inspired strategy has recently been developed for camouflaging nanocarriers with biomembranes, such as natural cell membranes or subcellular structure-derived membranes. This strategy endows cloaked nanomaterials with improved interfacial properties, superior cell targeting, immune evasion potential, and prolonged duration of systemic circulation. Here, we summarize recent advances in the production and application of exosomal membrane-coated nanomaterials. The structure, properties, and manner in which exosomes communicate with cells are first reviewed. This is followed by a discussion of the types of exosomes and their fabrication methods. We then discuss the applications of biomimetic exosomes and membrane-cloaked nanocarriers in tissue engineering, regenerative medicine, imaging, and the treatment of neurodegenerative diseases. Finally, we appraise the current challenges associated with the clinical translation of biomimetic exosomal membrane-surface-engineered nanovehicles and evaluate the future of this technology.

The role of biomechanical stress in extracellular vesicle formation, composition and activity

Extracellular vesicles (EVs) are cornerstones of intercellular communication with exciting fundamental, clinical, and more broadly biotechnological applications. However, variability in EV composition, which results from the culture conditions used to generate the EVs, poses significant fundamental and applied challenges and a hurdle for scalable bioprocessing. Thus, an understanding of the relationship between EV production (and for clinical applications, manufacturing) and EV composition is increasingly recognized as important and necessary. While chemical stimulation and culture conditions such as cell density are known to influence EV biology, the impact of biomechanical forces on the generation, properties, and biological activity of EVs remains poorly understood. Given the omnipresence of these forces in EV preparation and in biomanufacturing, expanding the understanding of their impact on EV composition-and thus, activity-is vital. Although several publications have examined EV preparation and bioprocessing and briefly discussed biomechanical stresses as variables of interest, this review represents the first comprehensive evaluation of the impact of such stresses on EV production, composition and biological activity. We review how EV biogenesis, cargo, efficacy, and uptake are uniquely affected by various types, magnitudes, and durations of biomechanical forces, identifying trends that emerge both generically and for individual cell types. We also describe implications for scalable bioprocessing, evaluating processes inherent in common EV production and isolation methods, and propose a path forward for rigorous EV quality control.

Extracellular Vesicles and Their Mimetics: A Comparative Study of Their Pharmacological Activities and Immunogenicity Profiles

Extracellular vesicles (EVs), which are miniaturised carriers loaded with functional proteins, lipids, and nucleic acid material, are naturally secreted by cells and show intrinsic pharmacological effects in several conditions. As such, they have the potential to be used for the treatment of various human diseases. However, the low isolation yield and laborious purification process are obstacles to their translation for clinical use. To overcome this problem, our lab developed cell-derived nanovesicles (CDNs), which are EV mimetics produced by shearing cells through membrane-fitted spin cups. To evaluate the similarities between EVs and CDNs, we compare the physical properties and biochemical composition of monocytic U937 EVs and U937 CDNs. Besides having similar hydrodynamic diameters, the produced CDNs had proteomic, lipidomic, and miRNA profiles with key communalities compared to those of natural EVs. Further characterisation was conducted to examine if CDNs could exhibit similar pharmacological activities and immunogenicity when administered in vivo. Consistently, CDNs and EVs modulated inflammation and displayed antioxidant activities. EVs and CDNs both did not exert immunogenicity when administered in vivo. Overall, CDNs could serve as a scalable and efficient alternative to EVs for further translation into clinical use.

Research progress of exosomes in pathogenesis, diagnosis, and treatment of ocular diseases

Exosomes are natural extracellular vesicles with a diameter of 30-150 nm, which exist in biological fluids and contain biomolecules related to the parent cell, such as proteins, nucleic acids, lipids, etc. It has a wide range of biological functions, and participates in the regulation of important physiological and pathological activities of the body. It can be used as a biomarker for early diagnosis of ocular diseases, a potential therapeutic target, a targeted drug carrier, and has a high potential for clinical application. In this paper, we summarized the genesis mechanism, biological functions, research and application progress of exosomes, focused on the engineering strategy of exosomes, and summarized the advantages and disadvantages of common engineering exosome preparation methods. Systematically combed the role of exosomes in corneal diseases, glaucoma, and retinal diseases, to provide a reference for further understanding of the role of exosomes in the pathogenesis, diagnosis, and treatment of ocular diseases. Finally, we further summarized the opportunities and challenges of exosomes for precision medicine. The extension of exosome research to the field of ophthalmology will help advance current diagnostic and therapeutic methods. Tiny exosomes have huge potential.

High yield engineered nanovesicles from ADSC with enriched miR-21-5p promote angiogenesis in adipose tissue regeneration

BACKGROUND

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have been found to have a great potential for soft tissue repair due to various biological functions, including pro-angiogenesis and low immunogenicity. However, the low yield and heterogeneity of MSC-EVs limited their clinical transformation. This study was designed to develop a novel adipose-derived stem cell engineered nanovesicles (ADSC-NVs) with high production and explore its pro-angiogenetic effect and application in adipose tissue regeneration.

METHODS

Adipose-derived stem cell-derived extracellular vesicles (ADSC-EVs) were isolated from an EVs-free culture medium for human ADSCs (hADSCs). ADSC-NVs were prepared by sequentially extruding ADSCs followed by iodixanol density gradient ultracentrifugation and were compared with ADSC-EVs in morphology, size distribution, protein contents and yield. The pro-angiogenetic effect of ADSC-NVs in different doses (0, 5, 20 and 80 μg/mL) in vitro was determined using transwell assay, tube formation assay, western blot and qRT-PCR. In vivo, BALB/c nude mice were administered injection of a mixture of fat granules and different dose of ADSC-NVs and grafts were harvested at 12 weeks post-transplantation for further analysis. By analyzing the weight and volume of grafts and histological evaluation, we investigated the effect of ADSC-NVs in vessel formation and adipose tissue regeneration.

RESULTS

Our results showed yield of purified ADSC-NVs was approximately 20 times more than that of ADSC-EVs secreted by the same number of ADSCs. In vitro, both ADSC-NVs and ADSC-EVs exhibited a dose-dependent pro-angiogenetic effect, despite their distinct miRNA profiles. These effects of ADSC-NVs may be mediated by enriched miR-21-5p via PTEN inhibition and PI3K/p-Akt signaling activation. Furthermore, after a mixed injection of ADSC-NVs, vessel formation and adipose regeneration were observed in vivo in fat implants.

CONCLUSIONS

Our study developed a potent alternative of ADSC-EVs. ADSC-NVs have a high pro-angiogenesis potential and can be used as cell-free therapeutic biomaterials in soft tissue regeneration.

Recent advances in nanomaterials for the treatment of spinal cord injury

Spinal cord injuries (SCIs) are devastating. In SCIs, a powerful traumatic force impacting the spinal cord results in the permanent loss of nerve function below the injury level, leaving the patient paralyzed and wheelchair-bound for the remainder of his/her life. Unfortunately, clinical treatment that depends on surgical decompression appears to be unable to handle damaged nerves, and high-dose methylprednisolone-based therapy is also associated with problems, such as infection, gastrointestinal bleeding, femoral head necrosis, obesity, and hyperglycemia. Nanomaterials have opened new avenues for SCI treatment. Among them, performance-based nanomaterials derived from a variety of materials facilitate improvements in the microenvironment of traumatic injury and, in some cases, promote neuron regeneration. Nanoparticulate drug delivery systems enable the optimization of drug effects and drug bioavailability, thus contributing to the development of novel treatments. The improved efficiency and accuracy of gene delivery will also benefit the exploration of SCI mechanisms and the understanding of key genes and signaling pathways. Herein, we reviewed different types of nanomaterials applied to the treatment of SCI and summarized their functions and advantages to provide new perspectives for future clinical therapies.

Extracellular Vesicle Mimetics: Preparation from Top-Down Approaches and Biological Functions

Extracellular vesicles (EVs) have attracted attention as delivery vehicles due to their structure, composition, and unique properties in regeneration and immunomodulation. However, difficulties during production and isolation processes of EVs limit their large-scale clinical applications. EV mimetics (EVMs), prepared via top-down strategies that improve the yield of nanoparticles while retaining biological properties similar to those of EVs have been used to address these limitations. Herein, the preparation of EVMs is reviewed and their characteristics in terms of structure, composition, targeting ability, cellular uptake mechanism, and immunogenicity, as well as their strengths, limitations, and future clinical application prospects as EV alternatives are summarized.

Methods of the Large-Scale Production of Extracellular Vesicles

To date, extracellular vesicles (EVs) have been extensively investigated as potential substitutes for cell therapy. Research has suggested their ability to overcome serious risks associated with the application of these cells. Although, the translation of EVs into clinical practice is hampered by the lack of a cheap reasonable way to obtain a clinically relevant number of EVs, an available method for the large-scale production of EVs ensures vesicles’ integrity, preserves their biological activity, and ensures they are well reproducible, providing homogeneity of the product from batch to batch. In this review, advances in the development of methods to increase EVs production are discussed. The existing approaches can be divided into the following: (1) those based on increasing the production of natural EVs by creating and using high capacity “cell factories”, (2) those based on the induction of EVs secretion under various cell stressors, and (3) those based on cell fragmentation with the creation of biomimetic vesicles. The aim of this review is to stimulate the introduction of EVs into clinical practice and to draw attention to the development of new methods of EVs production on a large scale.

The in vivo fate and targeting engineering of crossover vesicle-based gene delivery system

Exosomes and biomimetic vesicles are widely used for gene delivery because of their excellent gene loading capacity and stability and their natural targeting delivery potential. These vesicles take advantages of both cell-based bioactive delivery system and synthetical lipid-derived nanovectors to form crossover characteristics. To further optimize the specific targeting properties of crossover vesicles, studies of their in vivo fate and various engineering approaches including nanobiotechnology are required. This review describes the preparation process of exosomes and biomimetic vesicles, and summarizes the mechanism of loading and delivery of nucleic acids or gene editing systems. We provide a comprehensive overview of the techniques employed for preparing the targeting crossover vesicles based on their cellular uptake and targeting mechanism. To delineate the future prospects of crossover vesicle gene delivery systems, various challenges and clinical applications of vesicles have also been discussed.

A Microfluidic Platform to Monitor Real-Time Effects of Extracellular Vesicle Exchange between Co-Cultured Cells across Selectively Permeable Barriers

Exosomes and other extracellular vesicles (EVs) play a significant yet poorly understood role in cell-cell communication during homeostasis and various pathological conditions. Conventional in vitro and in vivo approaches for studying exosome/EV function depend on time-consuming and expensive vesicle purification methods to obtain sufficient vesicle populations. Moreover, the existence of various EV subtypes with distinct functional characteristics and submicron size makes their analysis challenging. To help address these challenges, we present here a unique chip-based approach for real-time monitoring of cellular EV exchange between physically separated cell populations. The extracellular matrix (ECM)-mimicking Matrigel is used to physically separate cell populations confined within microchannels, and mimics tissue environments to enable direct study of exosome/EV function. The submicron effective pore size of the Matrigel allows for the selective diffusion of only exosomes and other smaller EVs, in addition to soluble factors, between co-cultured cell populations. Furthermore, the use of PEGDA hydrogel with a very small pore size of 1.2 nm in lieu of Matrigel allows us to block EV migration and, therefore, differentiate EV effects from effects that may be mediated by soluble factors. This versatile platform bridges purely in vitro and in vivo assays by enabling studies of EV-mediated cellular crosstalk under physiologically relevant conditions, enabling future exosome/EV investigations across multiple disciplines through real-time monitoring of vesicle exchange.

Emerging function and clinical significance of extracellular vesicle noncoding RNAs in lung cancer

Lung cancer (LC) is a commonly diagnosed cancer with an unsatisfactory prognosis. Extracellular vesicles (EVs) are lipid bilayer-delimited particles that mediate cell-cell communication by transporting various biomacromolecules, such as nucleic acids, proteins, and lipids. Noncoding RNAs (ncRNAs), including microRNAs, circular RNAs, and long noncoding RNAs, are important noncoding transcripts that play critical roles in a variety of physiological and pathological processes, especially in cancer. ncRNAs have been verified to be packaged into EVs and transported between LC cells and stromal cells, regulating multiple LC malignant phenotypes, such as proliferation, migration, invasion, epithelial-mesenchymal transition, metastasis, and treatment resistance. Additionally, EVs can be detected in various body fluids and are associated with the stage, grade, and metastasis of LC. Herein, we summarize the biological characteristics and functions of EV ncRNAs in the biological processes of LC, focusing on their potential to serve as diagnostic and prognostic biomarkers of LC as well as their probable role in the clinical treatment of LC. EV ncRNAs provide a new perspective for understanding the mechanism underlying LC pathogenesis and development, which might benefit numerous LC patients in the future.

Exosome-Based Treatment for Atherosclerosis

Atherosclerosis is an inflammatory disease in which lipids accumulate on the walls of blood vessels, thickening and clogging these vessels. It is well known that cell-to-cell communication is involved in the pathogenesis of atherosclerosis. Exosomes are extracellular vesicles that deliver various substances (e.g., RNA, DNA, and proteins) from the donor cell to the recipient cell and that play an important role in intercellular communication. Atherosclerosis can be either induced or inhibited through cell-to-cell communication using exosomes. An understanding of the function of exosomes as therapeutic tools and in the pathogenesis of atherosclerosis is necessary to develop new atherosclerosis therapies. In this review, we summarize the studies on the regulation of atherosclerosis through exosomes derived from multiple cells as well as research on exosome-based atherosclerosis treatment.

Stem Cell Mimicking Nanoencapsulation for Targeting Arthritis

Mesenchymal stem cells (MSCs) are considered a promising regenerative therapy due to their ability to migrate toward damaged tissues. The homing ability of MSCs is unique compared with that of non-migrating cells and MSCs are considered promising therapeutic vectors for targeting major cells in many pathophysiological sites. MSCs have many advantages in the treatment of malignant diseases, particularly rheumatoid arthritis (RA). RA is a representative autoimmune disease that primarily affects joints, and secreted chemokines in the joints are well recognized by MSCs following their migration to the joints. Furthermore, MSCs can regulate the inflammatory process and repair damaged cells in the joints. However, the functionality and migration ability of MSCs injected in vivo still show insufficient. The targeting ability and migration efficiency of MSCs can be enhanced by genetic engineering or modification, eg, overexpressing chemokine receptors or migration-related genes, thus maximizing their therapeutic effect. However, there are concerns about genetic changes due to the increased probability of oncogenesis resulting from genome integration of the viral vector, and thus, clinical application is limited. Furthermore, it is suspected that administering MSCs can promote tumor growth and metastasis in xenograft and orthotopic models. For this reason, MSC mimicking nanoencapsulations are an alternative strategy that does not involve using MSCs or bioengineered MSCs. MSC mimicking nanoencapsulations consist of MSC membrane-coated nanoparticles, MSC-derived exosomes and artificial ectosomes, and MSC membrane-fused liposomes with natural or genetically engineered MSC membranes. MSC mimicking nanoencapsulations not only retain the targeting ability of MSCs but also have many advantages in terms of targeted drug delivery. Specifically, MSC mimicking nanoencapsulations are capable of encapsulating drugs with various components, including chemotherapeutic agents, nucleic acids, and proteins. Furthermore, there are fewer concerns over safety issues on MSC mimicking nanoencapsulations associated with mutagenesis even when using genetically engineered MSCs, because MSC mimicking nanoencapsulations use only the membrane fraction of MSCs. Genetic engineering is a promising route in clinical settings, where nano-encapsulated technology strategies are combined. In this review, the mechanism underlying MSC homing and the advantages of MSC mimicking nanoencapsulations are discussed. In addition, genetic engineering of MSCs and MSC mimicking nanoencapsulation is described as a promising strategy for the treatment of immune-related diseases.

Packaging and Delivery of Asthma Therapeutics

Asthma is a life-altering, chronic disease of heterogenous origin that features a complex interplay of immune and environmental signaling. Although very little progress has been made in prevention, diverse types of medications and delivery systems, including nanoscale systems, have been or are currently being developed to control airway inflammation and prevent exacerbations and fibrosis. These medications are delivered through mechanical methods, with various inhalers (with benefits and drawbacks) existing, and new types offering some variety in delivery. Of particular interest is the progress being made in nanosized materials for efficient penetration into the epithelial mucus layer and delivery into the deepest parts of the lungs. Liposomes, nanoparticles, and extracellular vesicles, both natural and synthetic, have been explored in animal models of asthma and have produced promising results. This review will summarize and synthesize the latest developments in both macro-(inhaler) and micro-sized delivery systems for the purpose of treating asthma patients.

A systematic review on the modifications of extracellular vesicles: a revolutionized tool of nano-biotechnology

Background

Tailoring extracellular vesicles (EVs) can bequeath them with diverse functions and efficient performance in nano-biotechnology. Engineering and modification of EVs improves the targeted drug delivery efficiency. Here, we performed systematic review of various methods for EVs modifications.

Methods

PubMed, Scopus, ISI Web of Science, EMBASE, and Google Scholar were searched for available articles on EVs modifications (up to March 2021). In total, 1208 articles were identified and assessed, and then only 36 articles were found eligible and included.

Results

Six studies demonstrate the application of click chemistry, seven studies used co-incubation, two studies used chemical transfection, four studies implicated electroporation and sonication approach for modification of EVs. Moreover, two studies utilized microfluidics as suitable approach for loading cargo into EVs, while eight studies showed freeze–thaw method as feasible for these biological nanoparticles.

Conclusion

Freeze–thaw approach is found to be convenient and popular among researchers for performing modifications in EVs for the purpose of targeted drug delivery loading. Clinical-grade EVs production with good clinical practices (GCPs) is challenging in the current scenario. More studies are needed to determine the best suitable approach for cargo loading of EVs that may be exploited for research and therapeutic use.

Graphical Abstract

Extracellular vesicles (EVs) can be modified using various methods available including physical, chemical and engineering based. These tailoring methods are helpful in targeting drug delivery to treat various diseases. Moreover, EVs have the ability to modify that’s due to presence of lipid bilayer membrane, that’s effectively participate in loading and unloading of desired drug.

EVs expressed from the specific cell types can give useful information about the pathogenesis of a particular disease in the form of unique nucleic acids, protein and lipid sequences and therefore, EVs derived from these cells can be used as specific diagnostic biomarker for diagnosis of diseases.

Modified EVs using various drugs or miRNAs can be used for targeted drug delivery to specific cells.

Exosomes as Powerful Engines in Cancer: Isolation, Characterization and Detection Techniques

Exosomes, powerful extracellular nanovesicles released from almost all types of living cells, are considered the communication engines (messengers) that control and reprogram physiological pathways inside target cells within a community or between different communities. The cell-like structure of these extracellular vesicles provides a protective environment for their proteins and DNA/RNA cargos, which serve as biomarkers for many malicious diseases, including infectious diseases and cancers. Cancer-derived exosomes control cancer metastasis, prognosis, and development. In addition to the unique structure of exosomes, their nanometer size and tendency of interacting with cells makes them a viable novel drug delivery solution. In recent years, numerous research efforts have been made to quantify and characterize disease-derived exosomes for diagnosis, monitoring, and therapeutic purposes. This review aims to (1) relate exosome biomarkers to their origins, (2) focus on current isolation and detection methods, (3) discuss and evaluate the proposed technologies deriving from exosome research for cancer treatment, and (4) form a conclusion about the prospects of the current exosome research.

Cancer Patient Tissueoid with Self-Homing Nano-Targeting of Metabolic Inhibitor

The current paradigm of cancer medicine focuses on patient- and/or cancer-specific treatments, which has led to continuous progress in the development of patient representatives (e.g., organoids) and cancer-targeting carriers for drug screening. As breakthrough concepts, i) living cancer tissues convey intact profiles of patient-specific microenvironmental signatures. ii) The growth mechanisms of cancer mass with intense cell-cell interactions can be harnessed to develop self-homing nano-targeting by using cancer cell-derived nanovesicles (CaNVs). Hence, a tissueoid model of ovarian cancer (OC) is developed by culturing OC patient tissues in a 3D gel chip, whose microchannel networks enable perfusion to maintain tissue viability. A novel model of systemic cancer responses is approached by xenografting OC tissueoids into ischaemic hindlimbs in nude mice. CaNVs are produced to carry general chemotherapeutics or new drugs under pre/clinical studies that target the BRCA mutation or energy metabolism, thereby increasing the test scope. This pioneer study cross-validates drug responses from the OC clinic, tissueoid, and animal model by demonstrating the alignment of results in drug type-specific efficiency, BRCA mutation-dependent drug efficiency, and metabolism inhibition-based anti-cancer effects. Hence, this study provides a directional foundation to accelerate the discovery of patient-specific drugs with CaNV application towards future precision medicine.

Targeted extracellular vesicle delivery systems employing superparamagnetic iron oxide nanoparticles

In the past decade, the study of extracellular vesicles (EVs), especially exosomes (50-150 nm) have attracted growing interest in numerous areas of cancer and tissue regeneration due to their unique biological features. A low isolation yield and insufficient targeting abilities limit their therapeutic applicability. Recently, superparamagnetic iron oxide nanoparticles (SPIONs) with magnetic navigation have been exploited to enhance the targeting ability of EVs. To construct targeted EV delivery systems engineered by SPIONs, several groups have pioneered the use of different techniques, such as electroporation, natural incubation, and cell extrusion, to directly internalize SPIONs into EVs. Furthermore, some endogenous ligands, such as transferrins, antibodies, aptamers, and streptavidin, were shown to enable modification of SPIONs, which increases binding with EVs. In this review, we summarized recent advances in targeted EV delivery systems engineered by SPIONs and focused on the key methodological approaches and the current applications of magnetic EVs. This report aims to address the existing challenges and provide comprehensive insights into targeted EV delivery systems. STATEMENT OF SIGNIFICANCE: Targeted extracellular vesicle (EV) delivery systems engineered by superparamagnetic iron oxide nanoparticles (SPIONs) have attracted wide attention and research interest in recent years. Such strategies employ external magnet fields to manipulate SPION-functionalized EVs remotely, aiming to enhance their accumulation and penetration in vivo. Although iron oxide nanoparticle laden EVs are interesting, they are controversial at present, hampering the progress in their clinical application. A thorough integration of these studies is needed for an advanced insight and rational design of targeted EV delivery systems. In this review, we summarize the latest advances in the design strategies of targeted EV delivery systems engineered by SPIONs with a focus on their key methodological approaches, current applications, limitation and future perspectives, which may facilitate the development of natural theranostic nanoplatforms.

Dually targeted bioinspired nanovesicle delays advanced prostate cancer tumour growth in vivo

Prostate cancer (PC) is second-leading cancer in men, with limited treatment options available for men with advanced and metastatic PC. Prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) have been exploited as therapeutic targets in PC due to their upregulation in the advanced stages of the disease. To date, several PSA- and PSMA-activatable prodrugs have been developed to reduce the systemic toxicity of existing chemotherapeutics. Bioinspired nanovesicles have been exploited in drug delivery, offering prolonged drug blood circulation and higher tumour accumulation. For the first time, this study describes the engineering of dually targeted PSA/PSMA nanovesicles for advanced PC. PSMA-targeted bioinspired hybrids were prepared by hydrating a lipid film with anti-PSMA-U937 cell membranes and DOX-PSA prodrug, followed by extrusion. The bioinspired hybrids were characterised using dynamic light scattering, transmission electron microscopy, Dot blot, flow cytometry and Western blot. Cellular binding and toxicity studies in PC cancer cell lines were carried out using flow cytometry, confocal microscopy, and resazurin assay. Finally, tumour targeting and therapeutic efficacy studies were performed in solid and metastatic C4-2B-tumor-bearing mice. Interestingly, our PSMA-targeted hybrids demonstrated high cell uptake in PSMA-expressing cells with significant accumulation in solid and metastatic C4-2B tumour tissues following intravenous administration. More promisingly, our dually targeted PSA/PSMA hybrid significantly slowed down the C4-2B tumour growth in vivo, compared to free DOX-PSA and non-targeted PSA-hybrid. Our PSA/PSMA bioinspired hybrid could offer a highly selective treatment for advanced PC with lower side effects. STATEMENT OF SIGNIFICANCE: This study investigates a new approach to treat prostate cancer using dually targeted bioinspired nanovesicle . Our bioinspired vesicles are made mainly of a human blood cell membrane with a ligand recognising a specific marker (PSMA) on the surface of the prostate cancer cells. The present work describes the successful loading of a doxorubicin prodrug linked to a PSA- activatable peptide into these targeted bioinspired nanovesicle , where the active PSA enzyme presents in these cells converts the drug to its active form. Our dually targeted PSA/PSMA hybrid vesicles has successfully improved site-specific prodrug delivery to tackle advanced prostate cancer, offering a novel and effective prostate cancer treatment.

Techniques for increasing the yield of stem cell-derived exosomes: what factors may be involved?

Exosomes are nano-scale extracellular vesicles secreted by cells and constitute an important part in the cell-cell communication. The main contents of the exosomes include proteins, microRNAs, and lipids. The mechanism and safety of stem cell-derived exosomes have rendered them a promising therapeutic strategy for regenerative medicine. Nevertheless, limited yield has restrained full explication of their functions and clinical applications To address this, various attempts have been made to explore the up- and down-stream manipulations in a bid to increase the production of exosomes. This review has recapitulated factors which may influence the yield of stem cell-derived exosomes, including selection and culture of stem cells, isolation and preservation of the exosomes, and development of artificial exosomes.

Development of Extracellular Vesicle Therapeutics: Challenges, Considerations, and Opportunities

Extracellular vesicles (EVs) hold great promise as therapeutic modalities due to their endogenous characteristics, however, further bioengineering refinement is required to address clinical and commercial limitations. Clinical applications of EV-based therapeutics are being trialed in immunomodulation, tissue regeneration and recovery, and as delivery vectors for combination therapies. Native/biological EVs possess diverse endogenous properties that offer stability and facilitate crossing of biological barriers for delivery of molecular cargo to cells, acting as a form of intercellular communication to regulate function and phenotype. Moreover, EVs are important components of paracrine signaling in stem/progenitor cell-based therapies, are employed as standalone therapies, and can be used as a drug delivery system. Despite remarkable utility of native/biological EVs, they can be improved using bio/engineering approaches to further therapeutic potential. EVs can be engineered to harbor specific pharmaceutical content, enhance their stability, and modify surface epitopes for improved tropism and targeting to cells and tissues in vivo. Limitations currently challenging the full realization of their therapeutic utility include scalability and standardization of generation, molecular characterization for design and regulation, therapeutic potency assessment, and targeted delivery. The fields' utilization of advanced technologies (imaging, quantitative analyses, multi-omics, labeling/live-cell reporters), and utility of biocompatible natural sources for producing EVs (plants, bacteria, milk) will play an important role in overcoming these limitations. Advancements in EV engineering methodologies and design will facilitate the development of EV-based therapeutics, revolutionizing the current pharmaceutical landscape.

Recent Progress of Extracellular Vesicle Engineering

Extracellular vesicles (EVs) are nanoscale phospholipid bilayer membrane vesicles which contain varied active biomolecules. As natural carriers, EVs can deliver endogenous cargos to target tissues safely and effectively. However, the applications of natural released EVs are limited by their low yield and heterogeneity. Engineering EVs can endow them with more functions and better performances to address these issues. EVs can be modified and engineered to improve the yield, targeting efficiency, and content of beneficial cargos. Herein, the strategies of engineering EVs through genetic modification of EVs are introduced; the molecular modification of the EV membrane and the loading of nucleic acids are summarized; the building of EV mimetic nanovesicles are reviewed. Overall, we anticipate that readers will gain a better understanding of the progress of EV engineering, which will help to promote the development of the technologies and applications in this field.

Technological advances towards extracellular vesicles mass production

Extracellular vesicles (EVs) are becoming essential actors in bio-therapeutics, as much for their regenerative or immunomodulatory properties as for their potential as cargo delivery vehicles. To enable the democratization of these EV-based therapies, many challenges remain such as large-scale production which is necessary to reduce costs of treatment. Herein, we review some advanced works on high-yield EV manufacturing. One approach consists in developing large-scale cell culture platforms, while others focus on cell stimulation to increase particle yield per cell. This can be done by moderate physico-chemical stresses or by disrupting cell membrane towards autoassembled vesicle-like particles. We critically compare these different techniques, keeping in mind that the field still lacks shared characterization standards, underline the importance of therapeutic potency assessment and discuss mass production strategies that have been identified in current clinical trials.

Artificial exosomes for translational nanomedicine

Exosomes are lipid bilayer membrane vesicles and are emerging as competent nanocarriers for drug delivery. The clinical translation of exosomes faces many challenges such as massive production, standard isolation, drug loading, stability and quality control. In recent years, artificial exosomes are emerging based on nanobiotechnology to overcome the limitations of natural exosomes. Major types of artificial exosomes include 'nanovesicles (NVs)', 'exosome-mimetic (EM)' and 'hybrid exosomes (HEs)', which are obtained by top-down, bottom-up and biohybrid strategies, respectively. Artificial exosomes are powerful alternatives to natural exosomes for drug delivery. Here, we outline recent advances in artificial exosomes through nanobiotechnology and discuss their strengths, limitations and future perspectives. The development of artificial exosomes holds great values for translational nanomedicine.

Current strategies in tailoring methods for engineered exosomes and future avenues in biomedical applications

Exosomes are naturally occurring nanovesicles of endosomal origin, responsible for cellular communication. Depending on the cell type, exosomes display disparity in the cargo and are involved in up/down regulation of different biological pathways. Naturally secreted exosomes, owing to their inherent delivery potential, non-immunogenic nature and limited structural resemblance to the cells have emerged as ideal candidates for various drug delivery and therapeutic applications. Moreover, the structural versatility of exosomes provides greater flexibility for surface modifications to be made in the native configuration, by different methods, like genetic-engineering, chemical procedures, physical methods and microfluidic-technology, to enhance the cargo quality for expanded biomedical applications. Post isolation and prior to engineering exosomes for various applications, the internal and external structural compositions of exosomes are studied via different techniques. Efficiency and scalability of the exosome modification methods are pivotal in determining the scope of the technique for clinical applications. This review majorly focuses on different methods employed for engineering exosomes, and advantages/disadvantages associated with different tailoring approaches, along with the efficacy of engineered exosomes in biomedical applications. Further, the review highlights the importance of a relatively recent avenue for delivery of exosomes via scaffold-based delivery of naïve/engineered exosomes for regenerative medicine and tissue engineering. This review is based on the recent knowledge generated in this field and our comprehension in this domain.

The Role of Extracellular Vesicles in Disease Progression and Detection of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and one of the leading causes of cancer-related death worldwide. Despite the improvements in surveillance and treatment, the prognosis of HCC remains poor. Extracellular vesicles (EVs) are a heterogeneous group of phospholipid bilayer-enclosed particles circulating in the bloodstream and mediating intercellular communication. Emerging studies have shown that EVs play a crucial role in regulating the proliferation, immune escape, and metastasis of HCC. In addition, because EVs are present in the circulation at relatively early stages of disease, they are getting attention as an attractive biomarker for HCC detection. Over the past decade, dedicated efforts have been made to isolate EVs more efficiently and make them useful tools in different clinical settings. In this review article, we provide an overview of the EVs isolation methods and highlight the role of EVs as mediators in the pathogenesis and progression of HCC. Lastly, we summarize the potential applications of EVs in early-stage HCC detection.

Drug Delivery to the Bone Microenvironment Mediated by Exosomes: An Axiom or Enigma

The increasing incidence of bone-related disorders is causing a burden on the clinical scenario. Even though bone is one of the tissues that possess tremendous regenerative potential, certain bone anomalies need therapeutic intervention through appropriate delivery of a drug. Among several nanosystems and biologics that offer the potential to contribute towards bone healing, the exosomes from the class of extracellular vesicles are outstanding. Exosomes are extracellular nanovesicles that, apart from the various advantages, are standing out of the crowd for their ability to conduct cellular communication. The internal cargo of the exosomes is leading to its potential use in therapeutics. Exosomes are being unraveled in terms of the mechanism as well as application in targeting various diseases and tissues. Through this review, we have tried to understand and review all that is already established and the gap areas that still exist in utilizing them as drug delivery vehicles targeting the bone. The review highlights the potential of the exosomes towards their contribution to the drug delivery scenario in the bone microenvironment. A comparison of the pros and cons of exosomes with other prevalent drug delivery systems is also done. A section on the patents that have been generated so far from this field is included.

Engineered Extracellular Vesicles for Cancer Therapy

Extracellular vesicles (EVs) have emerged as a novel cell-free strategy for the treatment of many diseases including cancer. As a result of their natural properties to mediate cell-to-cell communication and their high physiochemical stability and biocompatibility, EVs are considered as excellent delivery vehicles for a variety of therapeutic agents such as nucleic acids and proteins, drugs, and nanomaterials. Increasing studies have shown that EVs can be modified, engineered, or designed to improve their efficiency, specificity, and safety for cancer therapy. Herein, a comprehensive overview of the recent advances in the strategies and methodologies of engineering EVs for scalable production and improved cargo-loading and tumor-targeting is provided. Additionally, the potential applications of engineered EVs in cancer therapy are discussed by presenting prominent examples, and the opportunities and challenges for translating engineered EVs into clinical practice are evaluated.