Biodistribution of Exosomes and Engineering Strategies for Targeted Delivery of Therapeutic Exosomes

Exosome may be the next generation of promising cell-free vaccines

Traditional vaccines have limits against some persistent infections and pathogens. The development of novel vaccine technologies is particularly critical for the future. Exosomes play an important role in physiological and pathological processes. Exosomes present many advantages, such as inherent capacity being biocompatible, non-toxic, which make them a more desirable candidate for vaccines. However, research on exosomes are in their infancy and the barriers of low yield, low purity, and weak targeting of exosomes limit their applications in vaccines. Accordingly, further exploration is necessary to improve these problems and subsequently facilitate the functional studies of exosomes. In this study, we reviewed the origin, classification, functions, modifications, separation and purification, and characterization methods of exosomes. Meanwhile, we focused on the role and mechanism of exosomes for cancer and COVID-19 vaccines.

Strategies for Targeting Peptide-Modified Exosomes and Their Applications in the Lungs

Exosomes belong to a subgroup of extracellular vesicles secreted by various cells and are involved in intercellular communication and material transfer. In recent years, exosomes have been used as drug delivery carriers because of their natural origin, high stability, low immunogenicity and high engineering ability. However, achieving targeted drug delivery with exosomes remains challenging. In this paper, a phage display technology was used to screen targeted peptides, and different surface modification strategies of targeted peptide exosomes were reviewed. In addition, the application of peptide-targeted exosomes in pulmonary diseases was also summarised.

Antioxidant Potential of Exosomes in Animal Nutrition

This review delves into the advantages of exosomes as novel antioxidants in animal nutrition and their potential for regulating oxidative stress. Although traditional nutritional approaches promote oxidative stress defense systems in mammalian animals, several issues remain to be solved, such as low bioavailability, targeted tissue efficiency, and high-dose by-effect. As an important candidate offering regulation opportunities concerned with cellular communication, disease prevention, and physiology regulation in multiple biological systems, the potential of exosomes in mediating redox status in biological systems has not been well described. A previously reported relationship between redox system regulation and circulating exosomes suggested exosomes as a fundamental candidate for both a regulator and biomarker for a redox system. Herein, we review the effects of oxidative stress on exosomes in animals and the potential application of exosomes as antioxidants in animal nutrition. Then, we highlight the advantages of exosomes as redox regulators due to their higher bioavailability and physiological heterogeneity-targeted properties, providing a theoretical foundation and feed industry application. Therefore, exosomes have shown great potential as novel antioxidants in the field of animal nutrition. They can overcome the limitations of traditional antioxidants in terms of dosage and side effects, which will provide unprecedented opportunities in nutritional management and disease prevention, and may become a major breakthrough in the field of animal nutrition.

Extracellular vesicles from the microalga Tetraselmis chuii are biocompatible and exhibit unique bone tropism along with antioxidant and anti-inflammatory properties

Extracellular vesicles (EVs) are membrane-enclosed bio-nanoparticles secreted by cells and naturally evolved to transport various bioactive molecules between cells and even organisms. These cellular objects are considered one of the most promising bio-nanovehicles for the delivery of native and exogenous molecular cargo. However, many challenges with state-of-the-art EV-based candidates as drug carriers still exist, including issues with scalability, batch-to-batch reproducibility, and cost-sustainability of the final therapeutic formulation. Microalgal extracellular vesicles, which we named nanoalgosomes, are naturally released by various microalgal species. Here, we evaluate the innate biological properties of nanoalgosomes derived from cultures of the marine microalgae Tetraselmis chuii, using an optimized manufacturing protocol. Our investigation of nanoalgosome biocompatibility in preclinical models includes toxicological analyses, using the invertebrate model organism Caenorhabditis elegans, hematological and immunological evaluations ex vivo and in mice. We evaluate nanoalgosome cellular uptake mechanisms in C. elegans at cellular and subcellular levels, and study their biodistribution in mice with accurate space-time resolution. Further examination highlights the antioxidant and anti-inflammatory bioactivities of nanoalgosomes. This holistic approach to nanoalgosome functional characterization demonstrates that they are biocompatible and innate bioactive effectors with unique bone tropism. These findings suggest that nanoalgosomes have significant potential for future therapeutic applications.

Recent progress in engineered extracellular vesicles and their biomedical applications

AIMS

To present the recent update on the isolation, engineering techniques for extracellular vesicles, limitations associated with different isolation techniques, different biomedical applications, and challenges of engineered extracellular vesicles for the benefit of researchers from academic, industry, etc. MATERIALS AND METHODS: Peer-reviewed articles from most recognized journals were collected, and presented information was analyzed to discuss collection, chemical, electroporation, cellular, and membrane surface engineering to design extracellular vesicles for various therapeutic applications. In addition, we present the applications and limitations of techniques for the collection of extracellular vesicles.

KEY FINDINGS

There is a need for isolation techniques with the gold standard. However, advanced extracellular vesicle isolation techniques showed improved recovery, and purity of extracellular vesicles. Tumor therapy is a major part of the therapy section that illustrates the role of engineered extracellular vesicles in synergetic therapy such as phototherapy, theragnostic, and delivery of genetic materials. In addition, extracellular vesicles have shown their potential in the treatment of retinal disorders, neurodegenerative disease, tuberculosis, osteoporosis, inflammatory bowel disease, vaccine production, and wound healing.

SIGNIFICANCE

Engineered extracellular vesicles can deliver cargo to the specific cells, elicit an immune response and could be used for the development of the vaccines in the future. However, the progress is at the initial stage. Overall, this review will provide a comprehensive understanding and could serve as a reference for researchers in the clinical translation of engineered extracellular vesicles in different biomedical fields.

Composition, functions, and applications of exosomal membrane proteins

Exosomes play a crucial role in various biological processes, such as human development, immune responses, and disease occurrence. The membrane proteins on exosomes are pivotal factors for their biological functionality. Currently, numerous membrane proteins have been identified on exosome membranes, participating in intercellular communication, mediating target cell recognition, and regulating immune processes. Furthermore, membrane proteins from exosomes derived from cancer cells can serve as relevant biomarkers for early cancer diagnosis. This article provides a comprehensive review of the composition of exosome membrane proteins and their diverse functions in the organism's biological processes. Through in-depth exploration of exosome membrane proteins, it is expected to offer essential foundations for the future development of novel biomedical diagnostics and therapies.

Engineered exosomes as a prospective therapy for diabetic foot ulcers

Diabetic foot ulcer (DFU), characterized by high recurrence rate, amputations and mortality, poses a significant challenge in diabetes management. The complex pathology involves dysregulated glucose homeostasis leading to systemic and local microenvironmental complications, including peripheral neuropathy, micro- and macro-angiopathy, recurrent infection, persistent inflammation and dysregulated re-epithelialization. Novel approaches to accelerate DFU healing are actively pursued, with a focus on utilizing exosomes. Exosomes are natural nanovesicles mediating cellular communication and containing diverse functional molecular cargos, including DNA, mRNA, microRNA (miRNA), lncRNA, proteins, lipids and metabolites. While some exosomes show promise in modulating cellular function and promoting ulcer healing, their efficacy is limited by low yield, impurities, low loading content and inadequate targeting. Engineering exosomes to enhance their curative activity represents a potentially more efficient approach for DFUs. This could facilitate focused repair and regeneration of nerves, blood vessels and soft tissue after ulcer development. This review provides an overview of DFU pathogenesis, strategies for exosome engineering and the targeted therapeutic application of engineered exosomes in addressing critical pathological changes associated with DFUs.

Proteome overview of exosome derived from plasma of cows infected with Mycobacterium bovis

Bovine tuberculosis (bTB), primarily caused by Mycobacterium bovis (M. bovis), is a globally zoonotic disease with significant economic impacts. Plasma exosomes have been extensively used for investigating disease processes and exploring biomarkers. While mass spectrometry (MS)-based proteomic analysis of plasma exosomes has been employed for human tuberculosis (TB) studies, it has not yet been applied to bTB. Therefore, a comprehensive proteomic overview of plasma exosomes from M. bovis-infected cows is essential. In this study, we presented an extensive proteomic analysis of plasma exosomes from 89 M. bovis-infected cows across three farms, using data dependent acquisition (DDA) mode. Our analysis encompasses 239,894 spectra, 6,011 peptides and 835 proteins. The proteomic overview revealed both consistencies and differences among individual cows, supplements 595 proteins to the bovine exosome library, and enriches tuberculosis and related pathways. Additionally, six pathways were validated as immune response pathways, and three proteins (CATHL1, H1-1, and LCN2) were identified as potential indicators of bTB. This study is the first to investigate the exosome proteome of plasma from cows infected with M. bovis, providing a valuable dataset for exploring candidate bTB markers and understanding the mechanisms of host defense against M. bovis.

Xenogeneic Transplantation Promoted Human Exosome Sequestration in Rat Specific Organs

Purpose

Here, we aimed to study the distribution pattern of normal and cancer xenogeneic exosomes (Exos) and possible interspecies reactions in a rat model.

Methods

Exos were isolated from normal Human umbilical vein endothelial cells (HUVECs) and MDA-MB-231 breast cancer cells. Diameter size and zeta potential distribution were studied using dynamic light scattering (DLS). The morphology of isolated Exos was monitored by scanning electron microscopy (SEM) images. Using western blotting, protein levels of exosomal tetraspanins were detected. For the in vivo study, Dil-labeled normal and cancer Exos were injected into the tail vein (100 µg exosomal protein/rat) three times at 1-hour intervals. After 24 hours, rats were euthanized and the cellular uptake of Exos was monitored in different organs using immunofluorescence staining (IF).

Results

The size distribution and mean zeta potential of HUVEC and MDA-MB-231 cells Exos were 80±29.94 and 64.77±25.49 nm, and -7.58 and -11.8 mV, respectively. Western blotting revealed CD9, CD81, and CD63 in normal and cancer Exos. The SEM images exhibited typical nano-sized round-shape Exo particles. IF staining indicated sequestration of administrated Exos in splenic tissue and lungs. The distribution of Exo in kidneys, aorta, and hepatic tissue was less. These features were more evident in the group that received cancer Exos. We found no obvious adverse effects in rats that received normal or cancer Exos.

Conclusion

Normal and cancerous xenogeneic human Exos can be sequestrated prominently in splenic tissue and lungs. Novel delivery approaches and engineering tools are helpful in the target delivery of administrated Exos to the injured sites.

New Origins of Yeast, Plant and Bacterial-Derived Extracellular Vesicles to Expand and Advance Compound Delivery

Extracellular vesicles (EVs) constitute a sophisticated molecular exchange mechanism highly regarded for their potential as a next-generation platform for compound delivery. However, identifying sustainable and biologically safe sources of EVs remains a challenge. This work explores the emergence of novel sources of plant and bacterial-based EVs, such as those obtained from food industry by-products, known as BP-EVs, and their potential to be used as safer and biocompatible nanocarriers, addressing some of the current challenges of the field. These novel sources exhibit remarkable oral bioavailability and biodistribution, with minimal cytotoxicity and a selective targeting capacity toward the central nervous system, liver, and skeletal tissues. Additionally, we review the ease of editing these recently uncovered nanocarrier-oriented vesicles using common EV editing methods, examining the cargo-loading processes applicable to these sources, which involve both passive and active functionalization methods. While the primary focus of these novel sources of endogenous EVs is on molecule delivery to the central nervous system and skeletal tissue based on their systemic target preference, their use, as reviewed here, extends beyond these key applications within the biotechnological and biomedical fields.

Priming mesenchymal stem cells to develop "super stem cells"

The stem cell pre-treatment approaches at cellular and sub-cellular levels encompass physical manipulation of stem cells to growth factor treatment, genetic manipulation, and chemical and pharmacological treatment, each strategy having advantages and limitations. Most of these pre-treatment protocols are non-combinative. This editorial is a continuum of Li et al's published article and Wan et al's editorial focusing on the significance of pre-treatment strategies to enhance their stemness, immunoregulatory, and immunosuppressive properties. They have elaborated on the intricacies of the combinative pre-treatment protocol using pro-inflammatory cytokines and hypoxia. Applying a well-defined multi-pronged combinatorial strategy of mesenchymal stem cells (MSCs), pre-treatment based on the mechanistic understanding is expected to develop "Super MSCs", which will create a transformative shift in MSC-based therapies in clinical settings, potentially revolutionizing the field. Once optimized, the standardized protocols may be used with slight modifications to pre-treat different stem cells to develop "super stem cells" with augmented stemness, functionality, and reparability for diverse clinical applications with better outcomes.

Mitigation of Oxidative Stress in Idiopathic Pulmonary Fibrosis Through Exosome-Mediated Therapies

Idiopathic pulmonary fibrosis (IPF) poses a formidable clinical challenge, characterized by the thickening of alveolar septa and the onset of pulmonary fibrosis. The pronounced activation of oxidative stress emerges as a pivotal hallmark of inflammation. Traditional application of exogenous antioxidants proves inadequate in addressing oxidative stress, necessitating exploration into strategies to augment their antioxidant efficacy. Exosomes, nano-sized extracellular vesicles harboring a diverse array of bioactive factors, present as promising carriers with the potential to meet this challenge. Recent attention has been directed towards the clinical applications of exosomes in IPF, fueling the impetus for this comprehensive review. We have compiled fresh insights into the role of exosomes in modulating oxidative stress in IPF and delved into their potential as carriers for regulating endogenous reactive oxygen species generation. This review endeavors to bridge the divide between exosome research and IPF, traversing from bedside to bench. Through the synthesis of recent findings, we propose exosomes as a novel and promising strategy for improving the outcomes of IPF therapy.

From bench to bedside: The promising value of exosomes in precision medicine for CNS tumors

Exosomes are naturally present extracellular vesicles (EVs) released into the surrounding body fluids upon the fusion of polycystic and plasma membranes. They facilitate intercellular communication by transporting DNA, mRNA, microRNA, long non-coding RNA, circular RNA, proteins, lipids, and nucleic acids. They contribute to the onset and progression of Central Nervous System (CNS) tumors. In addition, they can be used as biomarkers of tumor proliferation, migration, and blood vessel formation, thereby affecting the Tumor Microenvironment (TME). This paper reviews the recent advancements in the diagnosis and treatment of exosomes in various CNS tumors, the promise and challenges of exosomes as natural carriers of CNS tumors, and the therapeutic prospects of exosomes in CNS tumors. Furthermore, we hope this research can contribute to the development of more targeted and effective treatments for central nervous system tumors.

Exosome: From biology to drug delivery

In recent years, different advancements have been observed in nanosized drug delivery systems. Factors such as stability, safety and targeting efficiency cause hindrances in the clinical translation of these synthetic nanocarriers. Therefore, researchers employed endogenous nanocarriers like exosomes as drug delivery vehicles that have an inherent ability to target more efficiently after appropriate functionalization and show higher biocompatibility and less immunogenicity and facilitate penetration through the biological barriers more quickly than the other available carriers. Exosomes are biologically derived lipid bilayer-enclosed nanosized extracellular vesicles (size ranges from 30 to 150 nm) secreted from both prokaryotic and eukaryotic cells and appears significantly in the extracellular space. These EVs (extracellular vesicles) can exist in different sources, including mammals, plants and microorganisms. Different advanced techniques have been introduced for the isolation of exosomes to overcome the existing barriers present with conventional methods. Extensive research on the application of exosomes in therapeutic delivery for treating various diseases related to central nervous system, bone, cancer, skin, etc. has been employed. Several studies are on different stages of clinical trials, and many exosomes patents have been registered.

Engineered dendritic cells-derived exosomes harboring HIV-1 Nefmut-Tat fusion protein and heat shock protein 70: A promising HIV-1 safe vaccine candidate

Antigen presenting cells (APCs)-derived exosomes are nano-vesicles that can induce antigen-specific T cell responses, and possess therapeutic effects in clinical settings. Moreover, dendritic cells (DCs)-based vaccines have been developed to combat human immunodeficiency virus-1 (HIV-1) infection in preclinical and clinical trials. We investigated the immunostimulatory effects (B- and T-cells activities) of DCs- and exosomes-based vaccine constructs harboring HIV-1 Nefmut-Tat fusion protein as an antigen candidate and heat shock protein 70 (Hsp70) as an adjuvant in mice. The modified DCs and engineered exosomes harboring Nefmut-Tat protein or Hsp70 were prepared using lentiviral vectors compared to electroporation, characterized and evaluated by in vitro and in vivo immunological tests. Our data indicated that the engineered exosomes induced high levels of total IgG, IgG2a, IFN-γ, TNF-α and Granzyme B. Moreover, co-injection of exosomes harboring Hsp70 could significantly increase the secretion of antibodies, cytokines and Granzyme B. The highest levels of IFN-γ and TNF-α were observed in exosomes harboring Nefmut-Tat combined with exosomes harboring Hsp70 (Exo-Nefmut-Tat + Exo-Hsp70) regimen after single-cycle replicable (SCR) HIV-1 exposure. Generally, Exo-Nefmut-Tat + Exo-Hsp70 regimen can be considered as a promising safe vaccine candidate due to high T-cells (Th1 and CTL) activity and its maintenance against SCR HIV-1 exposure.

The Therapeutic Potential of Human Umbilical Cord Mesenchymal Stromal Cells Derived Exosomes for Wound Healing: Harnessing Exosomes as a Cell-free Therapy

Wound healing is a complicated process that involves many different types of cells and signaling pathways. Mesenchymal stromal cells (MSCs) have shown great potential as a treatment to improve wound healing because they can modulate inflammation, promote the growth of new blood vessels, and stimulate the regeneration of tissue. Recent evidence indicates MSCs-derived extracellular vesicles known as exosomes may mediate many of the therapeutic effects of MSCs on wound healing. Exosomes contain bioactive molecules such as proteins, lipids, and RNAs that can be transferred to recipient cells to modulate cellular responses. This article reviews current evidence on the mechanisms and therapeutic effects of human umbilical cord MSCs (hUCMSCs)-derived exosomes on wound healing. In vitro and animal studies demonstrate that hUCMSC-derived exosomes promote fibroblast proliferation/migration, angiogenesis, and re-epithelialization while reducing inflammation and scar formation. These effects are mediated by exosomal transfer of cytokines, growth factors, and regulatory microRNAs that modulate signaling pathways involved in wound healing. Challenges remain in exosome isolation methods, optimizing targeting/retention, and translation to human studies. Nevertheless, hUCMSCs-derived exosomes show promise as a novel cell-free therapeutic approach to accelerate wound closure and improve healing outcomes. Further research is warranted to fully characterize hUCMSCs-exosomal mechanisms and explore their clinical potential for wound management.

Functionalized nanoparticles to deliver nucleic acids to the brain for the treatment of Alzheimer's disease

Brain-targeted gene delivery across the blood-brain barrier (BBB) is a significant challenge in the 21st century for the healthcare sector, particularly in developing an effective treatment strategy against Alzheimer's disease (AD). The Internal architecture of the brain capillary endothelium restricts bio-actives entry into the brain. Additionally, therapy with nucleic acids faces challenges like vulnerability to degradation by nucleases and potential immune responses. Functionalized nanocarrier-based gene delivery approaches have resulted in safe and effective platforms. These nanoparticles (NPs) have demonstrated efficacy in protecting nucleic acids from degradation, enhancing transport across the BBB, increasing bioavailability, prolonging circulation time, and regulating gene expression of key proteins involved in AD pathology. We provided a detailed review of several nanocarriers and targeting ligands such as cell-penetrating peptides (CPPs), endogenous proteins, and antibodies. The utilization of functionalized NPs extends beyond a singular system, serving as a versatile platform for customization in related neurodegenerative diseases. Only a few numbers of bioactive regimens can go through the BBB. Thus, exploring functionalized NPs for brain-targeted gene delivery is of utmost necessity. Currently, genes are considered high therapeutic potential molecules for altering any disease-causing gene. Through surface modification, nanoparticulate systems can be tailored to address various diseases by replacing the target-specific molecule on their surface. This review article presents several nanoparticulate delivery systems, such as lipid NPs, polymeric micelles, exosomes, and polymeric NPs, for nucleic acids delivery to the brain and the functionalization strategies explored in AD research.

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.

Exosomes encapsulated in hydrogels for effective central nervous system drug delivery

The targeted delivery of pharmacologically active molecules, metabolites, and growth factors to the brain parenchyma has become one of the major challenges following the onset of neurodegeneration and pathological conditions. The therapeutic effect of active biomolecules is significantly impaired after systemic administration in the central nervous system (CNS) because of the blood-brain barrier (BBB). Therefore, the development of novel therapeutic approaches capable of overcoming these limitations is under discussion. Exosomes (Exo) are nano-sized vesicles of endosomal origin that have a high distribution rate in biofluids. Recent advances have introduced Exo as naturally suitable bio-shuttles for the delivery of neurotrophic factors to the brain parenchyma. In recent years, many researchers have attempted to regulate the delivery of Exo to target sites while reducing their removal from circulation. The encapsulation of Exo in natural and synthetic hydrogels offers a valuable strategy to address the limitations of Exo, maintaining their integrity and controlling their release at a desired site. Herein, we highlight the current and novel approaches related to the application of hydrogels for the encapsulation of Exo in the field of CNS tissue engineering.

Extracellular vesicles as nanotheranostic platforms for targeted neurological disorder interventions

Central Nervous System (CNS) disorders represent a profound public health challenge that affects millions of people around the world. Diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and traumatic brain injury (TBI) exemplify the complexities and diversities that complicate their early detection and the development of effective treatments. Amid these challenges, the emergence of nanotechnology and extracellular vesicles (EVs) signals a new dawn for treating and diagnosing CNS ailments. EVs are cellularly derived lipid bilayer nanosized particles that are pivotal in intercellular communication within the CNS and have the potential to revolutionize targeted therapeutic delivery and the identification of novel biomarkers. Integrating EVs with nanotechnology amplifies their diagnostic and therapeutic capabilities, opening new avenues for managing CNS diseases. This review focuses on examining the fascinating interplay between EVs and nanotechnology in CNS theranostics. Through highlighting the remarkable advancements and unique methodologies, we aim to offer valuable perspectives on how these approaches can bring about a revolutionary change in disease management. The objective is to harness the distinctive attributes of EVs and nanotechnology to forge personalized, efficient interventions for CNS disorders, thereby providing a beacon of hope for affected individuals. In short, the confluence of EVs and nanotechnology heralds a promising frontier for targeted and impactful treatments against CNS diseases, which continue to pose significant public health challenges. By focusing on personalized and powerful diagnostic and therapeutic methods, we might improve the quality of patients.

Mesenchymal stem cell-derived extracellular vesicles: a regulator and carrier for targeting bone-related diseases

The escalating threat of bone-related diseases poses a significant challenge to human health. Mesenchymal stem cell (MSC)-derived extracellular vesicles (MSC-EVs), as inherent cell-secreted natural products, have emerged as promising treatments for bone-related diseases. Leveraging outstanding features such as high biocompatibility, low immunogenicity, superior biological barrier penetration, and extended circulating half-life, MSC-EVs serve as potent carriers for microRNAs (miRNAs), long no-code RNAs (lncRNAs), and other biomolecules. These cargo molecules play pivotal roles in orchestrating bone metabolism and vascularity through diverse mechanisms, thereby contributing to the amelioration of bone diseases. Additionally, engineering modifications enhance the bone-targeting ability of MSC-EVs, mitigating systemic side effects and bolstering their clinical translational potential. This review comprehensively explores the mechanisms through which MSC-EVs regulate bone-related disease progression. It delves into the therapeutic potential of MSC-EVs as adept drug carriers, augmented by engineered modification strategies tailored for osteoarthritis (OA), rheumatoid arthritis (RA), osteoporosis, and osteosarcoma. In conclusion, the exceptional promise exhibited by MSC-EVs positions them as an excellent solution with considerable translational applications in clinical orthopedics.

Exosomes as a therapeutic tool to promote neurorestoration and cognitive function in neurological conditions: Achieve two ends with a single effort

Exosomes possess a significant role in intercellular communications. In the nervous system, various neural cells release exosomes that not only own a role in intercellular communications but also eliminate the waste of cells, maintain the myelin sheath, facilitate neurogenesis, and specifically assist in normal cognitive function. In neurological conditions including Parkinson's disease (PD), Alzheimer's disease (AD), traumatic brain injury (TBI), and stroke, exosomal cargo like miRNAs take part in the sequela of conditions and serve as a diagnostic tool of neurological disorders, too. Exosomes are not only a diagnostic tool but also their inhibition or administration from various sources like mesenchymal stem cells and serum, which have shown a worthy potential to treat multiple neurological disorders. In addition to neurodegenerative manifestations, cognitive deficiencies are an integral part of neurological diseases, and applying exosomes in improving both aspects of these diseases has been promising. This review discusses the status of exosome therapy in improving neurorestorative and cognitive function following neurological disease.

Unlocking the potential of exosomes: a breakthrough in the theranosis of degenerative orthopaedic diseases

Degenerative orthopaedic diseases pose a notable worldwide public health issue attributable to the global aging population. Conventional medical approaches, encompassing physical therapy, pharmaceutical interventions, and surgical methods, face obstacles in halting or reversing the degenerative process. In recent times, exosome-based therapy has gained widespread acceptance and popularity as an effective treatment for degenerative orthopaedic diseases. This therapeutic approach holds the potential for "cell-free" tissue regeneration. Exosomes, membranous vesicles resulting from the fusion of intracellular multivesicles with the cell membrane, are released into the extracellular matrix. Addressing challenges such as the rapid elimination of natural exosomes in vivo and the limitation of drug concentration can be effectively achieved through various strategies, including engineering modification, gene overexpression modification, and biomaterial binding. This review provides a concise overview of the source, classification, and preparation methods of exosomes, followed by an in-depth analysis of their functions and potential applications. Furthermore, the review explores various strategies for utilizing exosomes in the treatment of degenerative orthopaedic diseases, encompassing engineering modification, gene overexpression, and biomaterial binding. The primary objective is to provide a fresh viewpoint on the utilization of exosomes in addressing bone degenerative conditions and to support the practical application of exosomes in the theranosis of degenerative orthopaedic diseases.

Stem Cell-Derived Exosomes: An Advanced Horizon to Cancer Regenerative Medicine

Cancer research has made significant progress in recent years, and extracellular vesicles (EVs) based cancer investigation reveals several facts about cancer. Exosomes are a subpopulation of EVs. In the present decade, exosomes is mostly highlighted for cancer theranostic research. Tumor cell derived exosomes (TEXs) promote cancer but there are multiple sources of exosomes that can be used as cancer therapeutic agents (plant exosomes, stem cell-derived exosomes, modified or synthetic exosomes). Stem cells based regenerative medicine faces numerous challenges, such as promote tumor development, cellular reprogramming etc., and therefore addressing these complications becomes essential. Stem cell-derived exosomes serves as an answer to these problems and offers a better solution. Global research indicates that stem cell-derived exosomes also play a dual role in the cellular system by either inhibiting or promoting cancer. Modified exosomes which are genetically engineered exosomes or surface modified exosomes to increase the efficacy of the therapeutic properties can also be considered to target the above concerns. However, the difficulties associated with the exosomes include variations in exosomes heterogenity, isolation protocols, large scale production, etc., and these have to be managed effectively. In this review, we explore exosomes biogenesis, multiple stem cell-derived exosome sources, drug delivery, modified stem cells exosomes, clinical trial of stem cells exosomes, and the related challenges in this domain and future orientation. This article may encourage researchers to explore stem cell-derived exosomes and develop an effective and affordable cancer therapeutic solution.

Exosome-mediated delivery and regulation in neurological disease progression

Exosomes (EXOs), membranous structures originating from diverse biological sources, have recently seized the attention of researchers due to their theranostic potential for neurological diseases. Released actively by various cells, including stem cells, adipose tissue, and immune cells, EXOs wield substantial regulatory influence over the intricate landscape of neurological complications, exhibiting both positive and negative modulatory effects. In AD, EXOs play a pivotal role in disseminating and breaking down amyloid-β protein. Moreover, EXOs derived from mesenchymal stem cells showcase a remarkable capacity to mitigate pro-inflammatory phenotypes by regulating miRNAs in neurodegenerative diseases. These vesicles possess the unique ability to traverse the blood-brain barrier, governing the aggregation of mutant huntingtin protein. Understanding the exosomal functions within the CNS holds significant promise for enhancing treatment efficacy in neurological diseases. This review intricately examines the regulatory mechanisms involving EXOs in neurological disease development, highlighting therapeutic prospects and exploring their utility in exosome-based nanomedicine for various neurological complications. Additionally, the review highlights the challenges associated with drug delivery to the brain, emphasizing the complexities inherent in this critical aspect of neurotherapeutics.

Exosomes in renal cell carcinoma: challenges and opportunities

Renal cell carcinoma (RCC) is the most common type of kidney cancer that accounts for approximately 2-3% of adult malignancies. Among the primary treatment methods for this type of cancer are surgery and targeted treatment. Still, due to less than optimal effectiveness, there are problems such as advanced distant metastasis, delayed diagnosis, and drug resistance that continue to plague patients. In recent years, therapeutic advances have increased life expectancy and effective treatment in renal cell carcinoma patients. One of these methods is the use of stem cells. Although the therapeutic effects of stem cells, especially mesenchymal stem cells, are still impressive, today, extracellular vesicles (EVs) as carrying molecules and various mediators in intercellular communications, having a central role in tumorigenesis, metastasis, immune evasion, and drug response, and on the other hand, due to its low immunogenicity and strong regulatory properties of the immune system, has received much attention from researchers and doctors. Despite the increasing interest in exosomes as the most versatile type of EVs, the heterogeneity of their efficacy presents challenges and, on the other hand, exciting opportunities for diagnostic and clinical interventions.In the upcoming article, we will review the various aspects of exosomes' effects in the prevention, treatment, and progress of renal cell carcinoma and also ways to optimize them to strengthen their positive sides.

Engineered extracellular vesicles expressing ICAM-1: A promising targeted delivery system for T cell modifications

BACKGROUND

Extracellular vesicles (EVs) are natural nano-carriers that possess the required crucial features of an ideal biomolecular delivery system. However, using unmodified EVs may have some limitations such as low accumulation in target sites. Studies have established that engineering EVs against different cell surface markers can overcome most of these hurdles.

METHODS

In this study, engineered EVs expressing ICAM-1/LAMP2b fusion protein on their surfaces were produced and isolated. The uptake of isolated targeted and non-targeted EVs was evaluated by imaging and flow cytometry. To assess the ability of targeted EVs to be applied as a safe carrier, pAAVS1-Puro-GFP plasmids were encapsulated into EVs by electroporation.

RESULTS

The HEKT 293 cell line was successfully modified permanently by a lentiviral vector to express ICAM-1 on the surface of the derived EVs. The ELISA and western blot tests established the binding affinity of targeted EVs for recombinant LFA-1 with a remarkable difference from non-targeted EVs. Furthermore, flow cytometry results revealed noteworthy differences in the binding of LFA-1-positive, non-targeted EVs, and targeted EVs to LFA-1-negative cells. Finally, imaging and flow cytometry indicated that newly produced EVs could efficiently interact with T cells and functionally deliver loaded plasmids to them.

CONCLUSION

These LFA-1-targeted EVs were able to interact with T cells as their recipient cells. They can be utilized as an ideal delivery system to transfer various biomolecules to T cells, facilitating immunotherapies or other cell-based treatments.

Unlocking the potential of exosomes in cancer research: A paradigm shift in diagnosis, treatment, and prevention

Exosomes, which are tiny particles released by cells, have the ability to transport various molecules, including proteins, lipids, and genetic material containing non-coding RNAs (ncRNAs). They are associated with processes like cancer metastasis, immunity, and tissue repair. Clinical trials have shown exosomes to be effective in treating cancer, inflammation, and chronic diseases. Mesenchymal stem cells (MSCs) and dendritic cells (DCs) are common sources of exosome production. Exosomes have therapeutic potential due to their ability to deliver cargo, modulate the immune system, and promote tissue regeneration. Bioengineered exosomes could revolutionize disease treatment. However, more research is needed to understand exosomes in tumor growth and develop new therapies. This paper provides an overview of exosome research, focusing on cancer and exosome-based therapies including chemotherapy, radiotherapy, and vaccines. It explores exosomes as a drug delivery system for cancer therapy, highlighting their advantages. The article discusses using exosomes for various therapeutic agents, including drugs, antigens, and RNAs. It also examines challenges with engineered exosomes. Analyzing exosomes for clinical purposes faces limitations in sensitivity, specificity, and purification. On the other hand, Nanotechnology offers solutions to overcome these challenges and unlock exosome potential in healthcare. Overall, the article emphasizes the potential of exosomes for personalized and targeted cancer therapy, while acknowledging the need for further research.

Pulmonary Biodistribution of Platelet-Derived Regenerative Exosomes in a Porcine Model

The purpose of this study was to evaluate the biodistribution of a platelet-derived exosome product (PEP), previously shown to promote regeneration in the setting of wound healing, in a porcine model delivered through various approaches. Exosomes were labeled with DiR far-red lipophilic dye to track and quantify exosomes in tissue, following delivery via intravenous, pulmonary artery balloon catheter, or nebulization in sus scrofa domestic pigs. Following euthanasia, far-red dye was detected by Xenogen IVUS imaging, while exosomal protein CD63 was detected by Western blot and immunohistochemistry. Nebulization and intravenous delivery both resulted in global uptake of exosomes within the lung parenchyma. However, nebulization resulted in the greatest degree of exosome uptake. Pulmonary artery balloon catheter-guided delivery provided the further ability to localize pulmonary delivery. No off-target absorption was noted in the heart, spleen, or kidney. However, the liver demonstrated uptake primarily in nebulization-treated animals. Nebulization also resulted in uptake in the trachea, without significant absorption in the esophagus. Overall, this study demonstrated the feasibility of pulmonary delivery of exosomes using nebulization or intravenous infusion to accomplish global delivery or pulmonary artery balloon catheter-guided delivery for localized delivery.

Extracellular Vesicles and Hydrogels: An Innovative Approach to Tissue Regeneration

Extracellular vesicles have emerged as promising tools in regenerative medicine due to their inherent ability to facilitate intercellular communication and modulate cellular functions. These nanosized vesicles transport bioactive molecules, such as proteins, lipids, and nucleic acids, which can affect the behavior of recipient cells and promote tissue regeneration. However, the therapeutic application of these vesicles is frequently constrained by their rapid clearance from the body and inability to maintain a sustained presence at the injury site. In order to overcome these obstacles, hydrogels have been used as extracellular vesicle delivery vehicles, providing a localized and controlled release system that improves their therapeutic efficacy. This Review will examine the role of extracellular vesicle-loaded hydrogels in tissue regeneration, discussing potential applications, current challenges, and future directions. We will investigate the origins, composition, and characterization techniques of extracellular vesicles, focusing on recent advances in exosome profiling and the role of machine learning in this field. In addition, we will investigate the properties of hydrogels that make them ideal extracellular vesicle carriers. Recent studies utilizing this combination for tissue regeneration will be highlighted, providing a comprehensive overview of the current research landscape and potential future directions.

Understanding exosomes: Part 1-Characterization, quantification and isolation techniques

Exosomes are the smallest subset of extracellular signaling vesicles secreted by most cells with a diameter in the range of 30-150 nm. Their use has gained great momentum recently due to their ability to be utilized as diagnostic tools with a vast array of therapeutic applications. Over 5000 publications are currently being published yearly on this topic, and this number is only expected to dramatically increase as novel therapeutic strategies continue to be investigated. This review article first focuses on understanding exosomes, including their cellular origin, biogenesis, function, and characterization. Thereafter, overviews of the quantification methods and isolation techniques are given with discussion over their potential use as novel therapeutics in regenerative medicine.

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

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

Navigating the brain: the role of exosomal shuttles in precision therapeutics

Brain diseases have become one of the leading roots of mortality and disability worldwide, contributing a significant part of the disease burden on healthcare systems. The blood-brain barrier (BBB) is a primary physical and biological obstacle that allows only small molecules to pass through it. Its selective permeability is a significant challenge in delivering therapeutics into the brain for treating brain dysfunction. It is estimated that only 2% of the new central nervous system (CNS) therapeutic compounds can cross the BBB and achieve their therapeutic targets. Scientists are exploring various approaches to develop effective cargo delivery vehicles to promote better therapeutics targeting the brain with minimal off-target side effects. Despite different synthetic carriers, one of the natural brain cargo delivery systems, "exosomes," are now employed to transport drugs through the BBB. Exosomes are naturally occurring small extracellular vesicles (EVs) with unique advantages as a therapeutic delivery system for treating brain disorders. They have beneficial innate aspects of biocompatibility, higher stability, ability to cross BBB, low cytotoxicity, low immunogenicity, homing potential, targeted delivery, and reducing off-site target effects. In this review, we will discuss the limitations of synthetic carriers and the utilization of naturally occurring exosomes as brain-targeted cargo delivery vehicles and highlight the methods for modifying exosome surfaces and drug loading into exosomes. We will also enlist neurodegenerative disorders targeted with genetically modified exosomes for their treatment.

Encapsulation and assessment of therapeutic cargo in engineered exosomes: a systematic review

Exosomes are nanoscale extracellular vesicles secreted by cells and enclosed by a lipid bilayer membrane containing various biologically active cargoes such as proteins, lipids, and nucleic acids. Engineered exosomes generated through genetic modification of parent cells show promise as drug delivery vehicles, and they have been demonstrated to have great therapeutic potential for treating cancer, cardiovascular, neurological, and immune diseases, but systematic knowledge is lacking regarding optimization of drug loading and assessment of delivery efficacy. This review summarizes current approaches for engineering exosomes and evaluating their drug delivery effects, and current techniques for assessing exosome drug loading and release kinetics, cell targeting, biodistribution, pharmacokinetics, and therapeutic outcomes are critically examined. Additionally, this review synthesizes the latest applications of exosome engineering and drug delivery in clinical translation. The knowledge compiled in this review provides a framework for the rational design and rigorous assessment of exosomes as therapeutics. Continued advancement of robust characterization methods and reporting standards will accelerate the development of exosome engineering technologies and pave the way for clinical studies.

Research progress of extracellular vesicles in the treatment of ovarian diseases (Review)

The ovary is an essential reproductive organ in the female organism and its development seriously affects the physical and mental health of female patients. Ovarian diseases include ovarian cancer, premature ovarian insufficiency (POI) and polycystic ovary syndrome (PCOS). Women should pay attention to the most effective treatments for this condition because it is one of the most prevalent gynecological illnesses at present. Extracellular vesicles (EVs), which are smaller vesicles that mediate the exchange of cellular information, include the three categories of exosomes, microvesicles and apoptotic bodies. They are able to transport proteins, RNA and other substances to adjacent or distal cells, thus allowing cellular and tissue homeostasis to be maintained. Numerous previous studies have revealed that EVs are crucial for the treatment of ovarian diseases. They are known to transport its contents to ovarian cancer cells as well as other ovarian cells such as granulosa cells, affecting the development of ovarian disease processes. Therefore, this extracellular vesicle may be involved as a target in the therapeutic process of ovarian disease and may have great potential in the treatment of ovarian disease. In the present review, the role of EVs in the development of three ovarian diseases, including ovarian cancer, POI and PCOS, was mainly summarizes. It is expected that this will provide some theoretical support for the treatment of ovarian disease.

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.

Protocol for Testing Human Melanoma Exosomes that Shift the Healthy Phenotype of Human Dermal Cells

Exosomes are small membrane-derived vesicles that transmit DNA constituents, mRNAs, microRNAs, and proteins from donor cells to a receiver cell. Various cells comprising of mesenchymal, immune, and cancer cells discharge exosomes. Cancer cell exosomes form the entry and reprogramming of essentials connected to a tumor environment. Melanoma-derived exosomes transport diverse proteins such as c-MET and RAB27a, which leave a melanoma mark. Increased mesenchymal epithelial transition (MET) expressions in serum exosomes have been considered an indicator of disease progression. Meanwhile, RAB27a has been identified as being involved in exosome discharge and trafficking. Decreased expressions of RAB27a in human melanoma cells have shown to diminish exosome release.We examined the effects of the downregulation and upregulation of RAB27a and c-MET in human dermal fibroblasts by utilizing the isolated exosomes of malignant melanoma cell lines. Melanoma exosomes derived from cancer cells conveyed information to healthy dermal fibroblasts and stem cells while inducing phenotypic change. In this chapter, we show optimized protocols that were used by our group for in vitro analysis with melanoma exosomes.

The miR-210 Primed Endothelial Progenitor Cell Exosomes Alleviate Acute Ischemic Brain Injury

BACKGROUND

Stem cell-released exosomes (EXs) have shown beneficial effects on regenerative diseases. Our previous study has revealed that EXs of endothelial progenitor cells (EPC-EXs) can elicit favorable effects on endothelial function. EXs may vary greatly in size, composition, and cargo uptake rate depending on the origins and stimulus; notably, EXs are promising vehicles for delivering microRNAs (miRs). Since miR-210 is known to protect cerebral endothelial cell mitochondria by reducing oxidative stress, here we study the effects of miR-210-loaded EPC-EXs (miR210-EPC-EXs) on ischemic brain damage in acute ischemic stroke (IS).

METHODS

The miR210-EPC-EXs were generated from EPCs transfected with miR-210 mimic. Middle cerebral artery occlusion (MCAO) surgery was performed to induce acute IS in C57BL/6 mice. EPC-EXs or miR210-EPC-EXs were administrated via tail vein injection 2 hrs after IS. To explore the potential mechanisms, inhibitors of the vascular endothelial growth factor receptor 2 (VEGFR2)/PI3 kinase (PI3K) or tyrosine receptor kinase B (TrkB)/PI3k pathways were used. The brain tissue was collected after treatments for infarct size, cell apoptosis, oxidative stress, and protein expression (VEGFR2, TrkB) analyses on day two. The neurological deficit score (NDS) was evaluated before collecting the samples.

RESULTS

1) As compared to EPC-EXs, miR210-EPC-EXs profoundly reduced the infarct volume and improved the NDS on day two post-IS. 2) Fewer apoptosis cells were detected in the peri-infarct brain of mice treated with miR210-EPC-EXs than in EPC-EXs-treated mice. Meanwhile, the oxidative stress was profoundly reduced by miR210-EPC-EXs. 3) The ratios of p-PI3k/PI3k, p- VEGFR2/VEGFR2, and p-TrkB/TrkB in the ipsilateral brain were raised by miR210-EPC-EXs treatment. These effects could be significantly blocked or partially inhibited by PI3k, VEGFR2, or TrkB pathway inhibitors.

CONCLUSION

These findings suggest that miR210-EPC-EXs protect the brain from acute ischemia- induced cell apoptosis and oxidative stress partially through the VEGFR2/PI3k and TrkB/PI3k signal pathways.

Exosomes: Methods for Isolation and Characterization in Biological Samples

Exosomes are small lipid bilayer-encapsulated nanosized extracellular vesicles of endosomal origin. Exosomes are secreted by almost all cell types and are a crucial player in intercellular communication. Exosomes transmit cellular information from donor to recipient cells in the form of proteins, lipids, and nucleic acids and influence several physiological and pathological responses. Due to their capacity to carry a variety of cellular cargo, low immunogenicity and cytotoxicity, biocompatibility, and ability to cross the blood-brain barrier, these nanosized vesicles are considered excellent diagnostic tools and drug-delivery vehicles. Despite their tremendous potential, the progress in therapeutic applications of exosomes is hindered by inadequate isolation techniques, poor characterization, and scarcity of specific biomarkers. The current research in the field is focused on overcoming these limitations. In this chapter, we have reviewed conventional exosome isolation and characterization methods and recent advancements, their advantages and limitations, persistent challenges in exosome research, and future directions.

Simultaneous ischemic regions targeting and BBB crossing strategy to harness extracellular vesicles for therapeutic delivery in ischemic stroke

Extracellular vesicles (EVs) derived from adipose-derived stem cells (ADSC-EVs) hold great promise for ischemic stroke treatment, but their therapeutic efficacy is greatly limited due to insufficient targeting ability. Previous reports focused on single ischemic targeting or blood-brain barrier (BBB) penetration, precise delivery to the brain parenchyma has not been fully considered. This study leveraged the targeting ability of RGD peptide and the cell penetrating ability of Angiopep-2 peptide to deliver ADSC-EVs precisely to the impaired brain parenchyma. We found that dual-modified EVs (RA-EVs) significantly enhanced the transcellular permeability across BBB in vitro, and not only targeted ischemic blood vessels but also achieved rapid accumulation in the ischemic lesion area after intravenous administration in vivo. RA-EVs further decreased the infarct volume, apoptosis, BBB disruption, and neurobehavioral deficits. RNA sequencing revealed the molecular regulation mechanism after administration. These findings demonstrate that dual-modification optimizes brain parenchymal targeting and highlights the significance of recruitment and penetration as a previously unidentified strategy for harnessing EVs for therapeutic delivery in ischemic stroke.

Neuroprotective Effects and Therapeutic Potential of Dichloroacetate: Targeting Metabolic Disorders in Nervous System Diseases

Dichloroacetate (DCA) is an investigational drug used to treat lactic acidosis and malignant tumours. It works by inhibiting pyruvate dehydrogenase kinase and increasing the rate of glucose oxidation. Some studies have documented the neuroprotective benefits of DCA. By reviewing these studies, this paper shows that DCA has multiple pharmacological activities, including regulating metabolism, ameliorating oxidative stress, attenuating neuroinflammation, inhibiting apoptosis, decreasing autophagy, protecting the blood‒brain barrier, improving the function of endothelial progenitor cells, improving mitochondrial dynamics, and decreasing amyloid β-protein. In addition, DCA inhibits the enzyme that metabolizes it, which leads to peripheral neurotoxicity due to drug accumulation that may be solved by individualized drug delivery and nanovesicle delivery. In summary, in this review, we analyse the mechanisms of neuroprotection by DCA in different diseases and discuss the causes of and solutions to its adverse effects.

Schwann Cell-Derived Exosomal Vesicles: A Promising Therapy for the Injured Spinal Cord

Exosomes are nanoscale-sized membrane vesicles released by cells into their extracellular milieu. Within these nanovesicles reside a multitude of bioactive molecules, which orchestrate essential biological processes, including cell differentiation, proliferation, and survival, in the recipient cells. These bioactive properties of exosomes render them a promising choice for therapeutic use in the realm of tissue regeneration and repair. Exosomes possess notable positive attributes, including a high bioavailability, inherent safety, and stability, as well as the capacity to be functionalized so that drugs or biological agents can be encapsulated within them or to have their surface modified with ligands and receptors to imbue them with selective cell or tissue targeting. Remarkably, their small size and capacity for receptor-mediated transcytosis enable exosomes to cross the blood-brain barrier (BBB) and access the central nervous system (CNS). Unlike cell-based therapies, exosomes present fewer ethical constraints in their collection and direct use as a therapeutic approach in the human body. These advantageous qualities underscore the vast potential of exosomes as a treatment option for neurological injuries and diseases, setting them apart from other cell-based biological agents. Considering the therapeutic potential of exosomes, the current review seeks to specifically examine an area of investigation that encompasses the development of Schwann cell (SC)-derived exosomal vesicles (SCEVs) as an approach to spinal cord injury (SCI) protection and repair. SCs, the myelinating glia of the peripheral nervous system, have a long history of demonstrated benefit in repair of the injured spinal cord and peripheral nerves when transplanted, including their recent advancement to clinical investigations for feasibility and safety in humans. This review delves into the potential of utilizing SCEVs as a therapy for SCI, explores promising engineering strategies to customize SCEVs for specific actions, and examines how SCEVs may offer unique clinical advantages over SC transplantation for repair of the injured spinal cord.

Ultrasound-Targeted Microbubble Destruction Assisted Delivery of Platelet-Rich Plasma-Derived Exosomes Promoting Peripheral Nerve Regeneration

Peripheral nerve injury is prevalent and has a high disability rate in clinical settings. Current therapeutic methods have not achieved satisfactory efficacy, underscoring the need for novel approaches to nerve restoration that remains an active area of research in neuroscience and regenerative medicine. In this study, we isolated platelet-rich plasma-derived exosomes (PRP-exos) and found that they can significantly enhance the proliferation, migration, and secretion of trophic factors by Schwann cells (SCs). In addition, there were marked changes in transcriptional and expression profiles of SCs, particularly via the upregulation of genes related to biological functions involved in nerve regeneration and repair. In the rat model of sciatic nerve crush injury, ultrasound-targeted microbubble destruction (UTMD) enhanced the efficiency of PRP-exos delivery to the injury site. This approach ensured a high concentration of PRP-exos in the injured nerve and improved the therapeutic outcomes. In conclusion, PRP-exos may promote nerve regeneration and repair, and UTMD may increase the effectiveness of targeted PRP-exos delivery to the injured nerve and enhance the therapeutic effect.

Research Advances of Engineered Exosomes as Drug Delivery Carrier

Exosomes are nanoscale vesicles secreted by living cells that have similar membrane composition to parental cells and carry a variety of proteins, lipids, and nucleic acids. Therefore, exosomes have certain biological activities and play an important role in intercellular communication. On the basis of its potential as a carrier for drug delivery systems, exosomes have been engineered to compensate for the shortage of natural exosomes through various engineering strategies for improving drug delivery efficiency, enhancing targeting to tissues and organs, and extending the circulating half-life of exosomes. This review focuses on the engineered exosomes loading drugs through different strategies, discussions on exosome surface modification strategies, and summarizes the advantages and disadvantages of different strategies. In addition, this review provides an overview of the recent applications of engineered exosomes in a number of refractory and relapsable diseases. This review has the potential to provide a reference for further research and development of engineered exosomes.

Engineered exosomes for tissue regeneration: from biouptake, functionalization and biosafety to applications

Exosomes are increasingly recognized as important effector molecules that regulate intercellular signaling pathways. Notably, certain types of exosomes can induce therapeutic responses, including cell proliferation, angiogenesis, and tissue repair. The use of exosomes in therapy is a hot spot in current research, especially in regenerative medicine. Despite the therapeutic potential, problems have hindered their success in clinical applications. These shortcomings include low concentration, poor targeting and limited loading capability. To fully realize their therapeutic potential, certain modifications are needed in native exosomes. In the present review, we summarize the exosome modification and functionalization strategies. In addition, we provide an overview of potential clinical applications and highlight the issues associated with the biosafety and biocompatibility of engineered exosomes in applications.

Hypoxic regulation of extracellular vesicles: Implications for cancer therapy

Extracellular vesicles (EVs) play a pivotal role in intercellular communication and have been implicated in cancer progression. Hypoxia, a pervasive hallmark of cancer, is known to regulate EV biogenesis and function. Hypoxic EVs contain a specific set of proteins, nucleic acids, lipids, and metabolites, capable of reprogramming the biology and fate of recipient cells. Enhancing the intrinsic therapeutic efficacy of EVs can be achieved by strategically modifying their structure and contents. Moreover, the use of EVs as drug delivery vehicles holds great promise for cancer treatment. However, various hurdles must be overcome to enable their clinical application as cancer therapeutics. In this review, we aim to discuss the current knowledge on the hypoxic regulation of EVs. Additionally, we will describe the underlying mechanisms by which EVs contribute to cancer progression in hypoxia and outline the progress and limitations of hypoxia-related EV therapeutics for cancer.

Optimization of exosome-based cell-free strategies to enhance endogenous cell functions in tissue regeneration

Exosomes, nanoscale extracellular vesicles, play a crucial role in intercellular communication, owing to their biologically active cargoes such as RNAs and proteins. In recent years, they have emerged as a promising tool in the field of tissue regeneration, with the potential to initiate a new trend in cell-free therapy. However, it's worth noting that not all types of exosomes derived from cells are appropriate for tissue repair. Thus, selecting suitable cell sources is critical to ensure their efficacy in specific tissue regeneration processes. Current therapeutic applications of exosomes also encounter several limitations, including low-specific content for targeted diseases, non-tissue-specific targeting, and short retention time due to rapid clearance in vivo. Consequently, this review paper focuses on exosomes from diverse cell sources with functions specific to tissue regeneration. It also highlights the latest engineering strategies developed to overcome the functional limitations of natural exosomes. These strategies encompass the loading of specific therapeutic contents into exosomes, the endowment of tissue-specific targeting capability on the exosome surface, and the incorporation of biomaterials to extend the in vivo retention time of exosomes in a controlled-release manner. Collectively, these innovative approaches aim to synergistically enhance the therapeutic effects of natural exosomes, optimizing exosome-based cell-free strategies to boost endogenous cell functions in tissue regeneration. STATEMENT OF SIGNIFICANCE: Exosome-based cell-free therapy has recently emerged as a promising tool for tissue regeneration. This review highlights the characteristics and functions of exosomes from different sources that can facilitate tissue repair and their contributions to the regeneration process. To address the functional limitations of natural exosomes in therapeutic applications, this review provides an in-depth understanding of the latest engineering strategies. These strategies include optimizing exosomal contents, endowing tissue-specific targeting capability on the exosome surface, and incorporating biomaterials to extend the in vivo retention time of exosomes in a controlled-release manner. This review aims to explore and discuss innovative approaches that can synergistically improve endogenous cell functions in advanced exosome-based cell-free therapies for a broad range of tissue regeneration.

Exosomes in Cancer Progression and Therapy Resistance: Molecular Insights and Therapeutic Opportunities

The development of therapy resistance still represents a major hurdle in treating cancers, leading to impaired treatment success and increased patient morbidity. The establishment of minimally invasive liquid biopsies is a promising approach to improving the early diagnosis, as well as therapy monitoring, of solid tumors. Because of their manifold functions in the tumor microenvironment, tumor-associated small extracellular vesicles, referred to as exosomes, have become a subject of intense research. Besides their important roles in cancer progression, metastasis, and the immune response, it has been proposed that exosomes also contribute to the acquisition and transfer of therapy resistance, mainly by delivering functional proteins and RNAs, as well as facilitating the export of active drugs or functioning as extracellular decoys. Extensive research has focused on understanding the molecular mechanisms underlying the occurrence of resistance and translating these into strategies for early detection. With this review, we want to provide an overview of the current knowledge about the (patho-)biology of exosomes, as well as state-of-the-art methods of isolation and analysis. Furthermore, we highlight the role of exosomes in tumorigenesis and cancer treatment, where they can function as therapeutic agents, biomarkers, and/or targets. By focusing on their roles in therapy resistance, we will reveal new paths of exploiting exosomes for cancer diagnosis and treatment.

Engineered Exosomes as Theranostic Platforms for Cancer Treatment

Tremendous progress in nanotechnology and nanomedicine has made a significant positive effect on cancer treatment by integrating multicomponents into a single multifunctional nanosized delivery system for combinatorial therapies. Although numerous nanocarriers developed so far have achieved excellent therapeutic performance in mouse models via elegant integration of chemotherapy, photothermal therapy, photodynamic therapy, sonodynamic therapy, and immunotherapy, their synthetic origin may still cause systemic toxicity, immunogenicity, and preferential detection or elimination by the immune system. Exosomes, endogenous nanosized particles secreted by multiple biological cells, could be absorbed by recipient cells to facilitate intercellular communication and content delivery. Therefore, exosomes have emerged as novel cargo delivery tools and attracted considerable attention for cancer diagnosis and treatment due to their innate stability, biological compatibility, and biomembrane penetration capacity. Exosome-related properties and functions have been well-documented; however, there are few reviews, to our knowledge, with a focus on the combination of exosomes and nanotechnology for the development of exosome-based theranostic platforms. To make a timely review on this hot subject of research, we summarize the basic information, isolation and functionalization methodologies, diagnostic and therapeutic potential of exosomes in various cancers with an emphasis on the description of exosome-related nanomedicine for cancer theranostics. The existing appealing challenges and outlook in exosome clinical translation are finally introduced. Advanced biotechnology and nanotechnology will definitely not only promote the integration of intrinsic advantages of natural nanosized exosomes with traditional synthetic nanomaterials for modulated precise cancer treatment but also contribute to the clinical translations of exosome-based nanomedicine as theranostic nanoplatforms.

Potential applications of using tissue-specific EVs in targeted therapy and vaccinology

Many cell types secrete spherical membrane bodies classified as extracellular vesicles (EVs). EVs participate in intercellular communication and are present in body fluids, including blood, lymph, and cerebrospinal fluid. The time of EVs survival in the body varies depending on the body's localisation. Once the EVs reach cells, they trigger a cellular response. Three main modes of direct interaction of EVs with a target cell were described: receptor-ligand interaction mode, a direct fusion of EVs with the cellular membrane and EVs internalisation. Studies focused on the medical application of EVs. Medical application of EVs may require modification of their surface and interior. EVs surface was modified by affecting the parental cells or by the direct amendment of isolated EVs. The interior modification involved introducing materials into the cells or direct administrating isolated EVs. EVs carry proteins, lipids, fragments of DNA, mRNA, microRNA (miRNA) and long non-coding RNA. Because of EVs availability in liquid biopsy, they are potential diagnostic markers. Modified EVs could enhance the treatment of diseases such as colorectal cancer, Parkinson's disease, leukaemia or liver fibrosis. EVs have specific tissue tropisms, which makes them convenient organ-directed carriers of nucleic acids, drugs and vaccines. In conclusion, recently published works have shown that EVs could become biomarkers and modern vehicles of advanced drug forms.