Recent Advances in Extracellular Vesicles as Drug Delivery Systems and Their Potential in Precision Medicine

Exosomes based strategies for cardiovascular diseases: Opportunities and challenges

Exosomes, as nanoscale extracellular vesicles (EVs), are secreted by all types of cells to facilitate intercellular communication in living organisms. After being taken up by neighboring or distant cells, exosomes can alter the expression levels of target genes in recipient cells and thereby affect their pathophysiological outcomes depending on payloads encapsulated therein. The functions and mechanisms of exosomes in cardiovascular diseases have attracted much attention in recent years and are thought to have cardioprotective and regenerative potential. This review summarizes the biogenesis and molecular contents of exosomes and details the roles played by exosomes released from various cells in the progression and recovery of cardiovascular disease. The review also discusses the current status of traditional exosomes in cardiovascular tissue engineering and regenerative medicine, pointing out several limitations in their application. It emphasizes that some of the existing emerging industrial or bioengineering technologies are promising to compensate for these shortcomings, and the combined application of exosomes and biomaterials provides an opportunity for mutual enhancement of their performance. The integration of exosome-based cell-free diagnostic and therapeutic options will contribute to the further development of cardiovascular regenerative medicine.

Logic-Based Strategy for Spatiotemporal Release of Dual Extracellular Vesicles in Osteoarthritis Treatment

To effectively treat osteoarthritis (OA), the existing inflammation must be reduced before the cartilage damage can be repaired; this cannot be achieved with a single type of extracellular vesicles (EVs). Here, a hydrogel complex with logic-gates function is proposed that can spatiotemporally controlled release two types of EVs: interleukin 10 (IL-10)+ EVs to promote M2 polarization of macrophage, and SRY-box transcription factor 9 (SOX9)+ EVs to increase cartilage matrix synthesis. Following dose-of-action screening, the dual EVs are loaded into a matrix metalloporoteinase 13 (MMP13)-sensitive self-assembled peptide hydrogel (KM13E) and polyethylene glycol diacrylate/gelatin methacryloyl-hydrogel microspheres (PGE), respectively. These materials are mixed to form a "microspheres-in-gel" KM13E@PGE system. In vitro, KM13E@PGE abruptly released IL-10+ EVs after 3 days and slowly released SOX9+ EVs for more than 30 days. In vivo, KM13E@PGE increased the CD206+ M2 macrophage proportion in the synovial tissue and decreased the tumor necrosis factor-α and IL-1β levels. The aggrecan and SOX9 expressions in the cartilage tissues are significantly elevated following inflammation subsidence. This performance is not achieved using anti-inflammatory or cartilage repair therapy alone. The present study provides an injectable, integrated delivery system with spatiotemporal control release of dual EVs, and may inspire logic-gates strategies for OA treatment.

Postbiotics: Functional Food Materials and Therapeutic Agents for Cancer, Diabetes, and Inflammatory Diseases

Postbiotics are (i) "soluble factors secreted by live bacteria, or released after bacterial lysis, such as enzymes, peptides, teichoic acids, peptidoglycan-derived muropeptides, polysaccharides, cell-surface proteins and organic acids"; (ii) "non-viable metabolites produced by microorganisms that exert biological effects on the hosts"; and (iii) "compounds produced by microorganisms, released from food components or microbial constituents, including non-viable cells that, when administered in adequate amounts, promote health and wellbeing". A probiotic- and prebiotic-rich diet ensures an adequate supply of these vital nutrients. During the anaerobic fermentation of organic nutrients, such as prebiotics, postbiotics act as a benevolent bioactive molecule matrix. Postbiotics can be used as functional components in the food industry by offering a number of advantages, such as being added to foods that are harmful to probiotic survival. Postbiotic supplements have grown in popularity in the food, cosmetic, and healthcare industries because of their numerous health advantages. Their classification depends on various factors, including the type of microorganism, structural composition, and physiological functions. This review offers a succinct introduction to postbiotics while discussing their salient features and classification, production, purification, characterization, biological functions, and applications in the food industry. Furthermore, their therapeutic mechanisms as antibacterial, antiviral, antioxidant, anticancer, anti-diabetic, and anti-inflammatory agents are elucidated.

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.

Emerging advances in hydrogel-based therapeutic strategies for tissue regeneration

Significant developments in cell therapy and biomaterial science have broadened the therapeutic landscape of tissue regeneration. Tissue damage is a complex biological process in which different types of cells play a specific role in repairing damaged tissues and growth factors strictly regulate the activity of these cells. Hydrogels have become promising biomaterials for tissue regeneration if appropriate materials are selected and the hydrogel properties are well-regulated. Importantly, they can be used as carriers for living cells and growth factors due to the high water-holding capacity, high permeability, and good biocompatibility of hydrogels. Cell-loaded hydrogels can play an essential role in treating damaged tissues and open new avenues for cell therapy. There is ample evidence substantiating the ability of hydrogels to facilitate the delivery of cells (stem cell, macrophage, chondrocyte, and osteoblast) and growth factors (bone morphogenetic protein, transforming growth factor, vascular endothelial growth factor and fibroblast growth factor). This paper reviewed the latest advances in hydrogels loaded with cells or growth factors to promote the reconstruction of tissues. Furthermore, we discussed the shortcomings of the application of hydrogels in tissue engineering to promote their further development.

Challenges and future scope of exosomes in the treatment of cardiovascular diseases

Exosomes are nanosized vesicles that carry biologically diverse molecules for intercellular communication. Researchers have been trying to engineer exosomes for therapeutic purposes by using different approaches to deliver biologically active molecules to the various target cells efficiently. Recent technological advances may allow the biodistribution and pharmacokinetics of exosomes to be modified to meet scientific needs with respect to specific diseases. However, it is essential to determine an exosome's optimal dosage and potential side effects before its clinical use. Significant breakthroughs have been made in recent decades concerning exosome labelling and imaging techniques. These tools provide in situ monitoring of exosome biodistribution and pharmacokinetics and pinpoint targetability. However, because exosomes are nanometres in size and vary significantly in contents, a deeper understanding is required to ensure accurate monitoring before they can be applied in clinical settings. Different research groups have established different approaches to elucidate the roles of exosomes and visualize their spatial properties. This review covers current and emerging strategies for in vivo and in vitro exosome imaging and tracking for potential studies.

Engineered Extracellular Vesicles Derived from Dermal Fibroblasts Attenuate Inflammation in a Murine Model of Acute Lung Injury

Acute respiratory distress syndrome (ARDS) represents a significant burden to the healthcare system, with ≈200 000 cases diagnosed annually in the USA. ARDS patients suffer from severe refractory hypoxemia, alveolar-capillary barrier dysfunction, impaired surfactant function, and abnormal upregulation of inflammatory pathways that lead to intensive care unit admission, prolonged hospitalization, and increased disability-adjusted life years. Currently, there is no cure or FDA-approved therapy for ARDS. This work describes the implementation of engineered extracellular vesicle (eEV)-based nanocarriers for targeted nonviral delivery of anti-inflammatory payloads to the inflamed/injured lung. The results show the ability of surfactant protein A (SPA)-functionalized IL-4- and IL-10-loaded eEVs to promote intrapulmonary retention and reduce inflammation, both in vitro and in vivo. Significant attenuation is observed in tissue damage, proinflammatory cytokine secretion, macrophage activation, influx of protein-rich fluid, and neutrophil infiltration into the alveolar space as early as 6 h post-eEVs treatment. Additionally, metabolomics analyses show that eEV treatment causes significant changes in the metabolic profile of inflamed lungs, driving the secretion of key anti-inflammatory metabolites. Altogether, these results establish the potential of eEVs derived from dermal fibroblasts to reduce inflammation, tissue damage, and the prevalence/progression of injury during ARDS via nonviral delivery of anti-inflammatory genes/transcripts.

Angiopep-2 Modified Exosomes Load Rifampicin with Potential for Treating Central Nervous System Tuberculosis

Background

Central nervous system tuberculosis (CNS-TB) is the most devastating form of extrapulmonary tuberculosis. Rifampin (RIF) is a first-line antimicrobial agent with potent bactericidal action. Nonetheless, the blood-brain barrier (BBB) limits the therapeutic effects on CNS-TB. Exosomes, however, can facilitate drug movements across the BBB. In addition, exosomes show high biocompatibility and drug-loading capacity. They can also be modified to increase drug delivery efficacy. In this study, we loaded RIF into exosomes and modified the exosomes with a brain-targeting peptide to improve BBB permeability of RIF; we named these exosomes ANG-Exo-RIF.

Methods

Exosomes were isolated from the culture medium of BMSCs by differential ultracentrifugation and loaded RIF by electroporation and modified ANG by chemical reaction. To characterize ANG-Exo-RIF, Western blot (WB), nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM) were performed. Bend.3 cells were incubated with DiI labeled ANG-Exo-RIF and then fluorescent microscopy and flow cytometry were used to evaluate the targeting ability of ANG-Exo-RIF in vitro. Fluorescence imaging and frozen section were used to evaluate the targeting ability of ANG-Exo-RIF in vivo. MIC and MBC were determined through microplate alamar blue assay (MABA).

Results

A novel exosome-based nanoparticle was developed. Compared with untargeted exosomes, the targeted exosomes exhibited high targeting capacity and permeability in vitro and in vivo. The MIC and MBC of ANG-Exo-RIF were 0.25 μg/mL, which were sufficient to meet the clinical needs.

Conclusion

In summary, excellent targeting ability, high antitubercular activity and biocompatibility endow ANG-Exo-RIF with potential for use in future translation-aimed research and provide hope for an effective CNS-TB treatment.

Exosomes as Potential Functional Nanomaterials for Tissue Engineering

Exosomes are cell-derived extracellular vesicles of 40-160 nm diameter, which carry numerous biomolecules and transmit information between cells. They are used as functional nanomaterials with great potential in biomedical areas, such as active agents and delivery systems for advanced drug delivery and disease therapy. In recent years, potential applications of exosomes in tissue engineering have attracted significant attention, and some critical progress has been made. This review gives a complete picture of exosomes and their applications in the regeneration of various tissues, such as the central nervous systems, kidney, bone, cartilage, heart, and endodontium. Approaches employed for modifying exosomes to equip them with excellent targeting capacity are summarized. Furthermore, current concerns and future outlook of exosomes in tissue engineering are discussed.

Interleukin-4 Receptor Targeting Peptide Decorated Extracellular Vesicles as a Platform for In Vivo Drug Delivery to Thyroid Cancer

Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) have been demonstrated to deliver therapeutic drugs in preclinical studies. However, their use is limited, as they lack the ability to specifically deliver drugs to tumor tissues in vivo. In the present study, we propose the use of a targeting peptide, IL-4R-binding peptide (IL4RPep-1), to specifically deliver intravenously (i.v.) infused EVs to thyroid tumors. In vivo, a xenograft tumor model was treated with either the control peptide (NSSSVDK) or IL4RPep-1-Flamma; mice were fluorescently imaged (FLI) using an in vivo imaging system at 0–3 h post-treatment. EVs (labeled with DiD dye) were conjugated with IL4RPep-1 through a DOPE-NHS linker and administered to mice intravenously. FLI was performed 0–24 h post-injection, and the animals were sacrificed for further experiments. The morphology and size of EVs, the presence of EV markers such as CD63 and ALIX, and the absence of the markers GM130 and Cyto-C were confirmed. In vivo, FLI indicated an accumulation of i.v. injected IL4RPep-1-Flamma at the tumor site 90 min post-injection. No accumulation of NSSSVDK-Flamma was detected. In vivo, IL4RPep-1-EVs targeted the Cal-62 tumor 2 h post-injection. NSSSVDK-EVs were not even detected in the tumor 24 h post-injection. The quantification of FLI showed a significant accumulation of MSC-EVs in the tumor 2 h, 3 h, and 24 h post-injection. Furthermore, ex vivo imaging and an IF analysis confirmed the in vivo findings. Our results demonstrate the use of the IL4RPep-1 peptide as a targeting moiety of EVs for IL-4R-expressing anaplastic thyroid tumors.

Preparation of Recombinant Human Collagen III Protein Hydrogels with Sustained Release of Extracellular Vesicles for Skin Wound Healing

Existing treatment methods encounter difficulties in effectively promoting skin wound healing, making this a serious challenge for clinical treatment. Extracellular vesicles (EVs) secreted by stem cells have been proven to contribute to the regeneration and repair of wound tissue, but they cannot be targeted and sustained, which seriously limits their current therapeutic potential. The recombinant human collagen III protein (rhCol III) has the advantages of good water solubility, an absence of hidden viral dangers, a low rejection rate and a stable production process. In order to achieve a site-specific sustained release of EVs, we prepared a rhCol III hydrogel by cross-linking with transglutaminase (TGase) from Streptomyces mobaraensis, which has a uniform pore size and good biocompatibility. The release profile of the rhCol III-EVs hydrogel confirmed that the rhCol III hydrogel could slowly release EVs into the external environment. Herein, the rhCol III-EVs hydrogel effectively promoted macrophage changing from type M1 to type M2, the migration ability of L929 cells and the angiogenesis of human umbilical vein endothelial cells (HUVECs). Furthermore, the rhCol III-EVs hydrogel is shown to promote wound healing by inhibiting the inflammatory response and promoting cell proliferation and angiogenesis in a diabetic rat skin injury model. The reported results indicate that the rhCol III-EVs hydrogel could be used as a new biological material for EV delivery, and has a significant application value in skin wound healing.

The Effect of Lactobacillus plantarum Extracellular Vesicles from Korean Women in Their 20s on Skin Aging

Extracellular vesicles, which are highly conserved in most cells, contain biologically active substances. The vesicles and substances interact with cells and impact physiological mechanisms. The skin is the most external organ and is in direct contact with the external environment. Photoaging and skin damage are caused by extrinsic factors. The formation of wrinkles is a major indicator of skin aging and is caused by a decrease in collagen and hyaluronic acid. MMP-1 expression is also increased. Due to accruing damage, skin aging reduces the ability of the skin barrier, thereby lowering the skin’s ability to contain water and increasing the amount of water loss. L. plantarum suppresses various harmful bacteria by secreting an antimicrobial substance. L. plantarum is also found in the skin, and research on the interactions between the bacteria and the skin is in progress. Although several studies have investigated L. plantarum, there are only a limited number of studies on extracellular vesicles (EV) derived from L. plantarum, especially in relation to skin aging. Herein, we isolated EVs that were secreted from L. plantarum of women in their 20s (LpEVs). We then investigated the effect of LpEVs on skin aging in CCD986sk. We showed that LpEVs modulated the mRNA expression of ECM related genes in vitro. Furthermore, LpEVs suppressed wrinkle formation and pigmentation in clinical trials. These results demonstrated that LpEVs have a great effect on skin aging by regulating ECM related genes. In addition, our study offers important evidence on the depigmentation effect of LpEVs.

Applications of Extracellular Vesicles in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive and refractory subtype of breast cancer, often occurring in younger patients with poor clinical prognosis. Given the current lack of specific targets for effective intervention, the development of better treatment strategies remains an unmet medical need. Over the last decade, the field of extracellular vesicles (EVs) has grown tremendously, offering immense potential for clinical diagnosis/prognosis and therapeutic applications. While TNBC-EVs have been shown to play an important role in tumorigenesis, chemoresistance and metastasis, they could be repurposed as potential biomarkers for TNBC diagnosis and prognosis. Furthermore, EVs from various cell types can be utilized as nanoscale drug delivery systems (NDDS) for TNBC treatment. Remarkably, EVs generated from specific immune cell subsets have been shown to delay solid tumour growth and reduce tumour burden, suggesting a new immunotherapy approach for TNBC. Intrinsically, EVs can cross the blood-brain barrier (BBB), which holds great potential to treat the brain metastases diagnosed in one third of TNBC patients that remains a substantial clinical challenge. In this review, we present the most recent applications of EVs in TNBC as diagnostic/prognostic biomarkers, nanoscale drug delivery systems and immunotherapeutic agents, as well as discuss the associated challenges and future directions of EVs in cancer immunotherapy.

Mesenchymal Stem Cell-Derived Exosome Therapy of Microbial Diseases: From Bench to Bed

Microbial diseases are a global health threat, leading to tremendous casualties and economic losses. The strategy to treat microbial diseases falls into two broad categories: pathogen-directed therapy (PDT) and host-directed therapy (HDT). As the typical PDT, antibiotics or antiviral drugs directly attack bacteria or viruses through discerning specific molecules. However, drug abuse could result in antimicrobial resistance and increase infectious disease morbidity. Recently, the exosome therapy, as a HDT, has attracted extensive attentions for its potential in limiting infectious complications and targeted drug delivery. Mesenchymal stem cell-derived exosomes (MSC-Exos) are the most broadly investigated. In this review, we mainly focus on the development and recent advances of the application of MSC-Exos on microbial diseases. The review starts with the difficulties and current strategies in antimicrobial treatments, followed by a comprehensive overview of exosomes in aspect of isolation, identification, contents, and applications. Then, the underlying mechanisms of the MSC-Exo therapy in microbial diseases are discussed in depth, mainly including immunomodulation, repression of excessive inflammation, and promotion of tissue regeneration. In addition, we highlight the latest progress in the clinical translation of the MSC-Exo therapy, by summarizing related clinical trials, routes of administration, and exosome modifications. This review will provide fundamental insights and future perspectives on MSC-Exo therapy in microbial diseases from bench to bedside.

Made by cells for cells - extracellular vesicles as next-generation mainstream medicines

Current medicine has only taken us so far in reducing disease and tissue damage. Extracellular vesicles (EVs), which are membranous nanostructures produced naturally by cells, have been hailed as a next-generation medicine. EVs deliver various biomolecules, including proteins, lipids and nucleic acids, which can influence the behaviour of specific target cells. Since EVs not only mirror composition of their parent cells but also modify the recipient cells, they can be used in three key areas of medicine: regenerative medicine, disease detection and drug delivery. In this Review, we discuss the transformational and translational progress witnessed in EV-based medicine to date, focusing on two key elements: the mechanisms by which EVs aid tissue repair (for example, skin and bone tissue regeneration) and the potential of EVs to detect diseases at an early stage with high sensitivity and specificity (for example, detection of glioblastoma). Furthermore, we describe the progress and results of clinical trials of EVs and demonstrate the benefits of EVs when compared with traditional medicine, including cell therapy in regenerative medicine and solid biopsy in disease detection. Finally, we present the challenges, opportunities and regulatory framework confronting the clinical application of EV-based products.

Tissue-derived extracellular vesicles in cancers and non-cancer diseases: Present and future

Extracellular vesicles (EVs) are lipid‐bilayer membrane structures secreted by most cell types. EVs act as messengers via the horizontal transfer of lipids, proteins, and nucleic acids, and influence various pathophysiological processes in both parent and recipient cells. Compared to EVs obtained from body fluids or cell culture supernatants, EVs isolated directly from tissues possess a number of advantages, including tissue specificity, accurate reflection of tissue microenvironment, etc., thus, attention should be paid to tissue‐derived EVs (Ti‐EVs). Ti‐EVs are present in the interstitium of tissues and play pivotal roles in intercellular communication. Moreover, Ti‐EVs provide an excellent snapshot of interactions among various cell types with a common histological background. Thus, Ti‐EVs may be used to gain insights into the development and progression of diseases. To date, extensive investigations have focused on the role of body fluid‐derived EVs or cell culture‐derived EVs; however, the number of studies on Ti‐EVs remains insufficient. Herein, we summarize the latest advances in Ti‐EVs for cancers and non‐cancer diseases. We propose the future application of Ti‐EVs in basic research and clinical practice. Workflows for Ti‐EV isolation and characterization between cancers and non‐cancer diseases are reviewed and compared. Moreover, we discuss current issues associated with Ti‐EVs and provide potential directions.

Quantitative proteomic analysis for evaluating affinity isolation of extracellular vesicles

Absolute quantification with mass spectrometry and isotope labeled internal standards has found broad applications in biomedical research. In the present research, it was used for developing and evaluating a new affinity-based approach to isolate extracellular vesicles (EVs) from human plasma. First, a phage display peptide library was screened against EVs as a bait and absolute quantification of multiple proteins helped to select the best bait available. Then, absolute quantification was used to evaluate the efficiency of affinity chromatography on peptide-Sepharose. In summary, we have demonstrated that peptides with affinity to EVs selected from phage library screening can be valuable ligands for EVs isolation. SIGNIFICANCE: Extracellular vesicles (EVs) have an important role in intercellular communication for all cell types. This makes EVs a promising new type of therapeutics capable to deliver drugs to specific sites with no off-target side effects. However, their isolation, and correct assignment of their biological function and properties remains an obscure field of research. In this study, we proposed to use MRM quantitation of a pattern of EVs and non-EVs proteins to develop a purification protocol based on affinity peptides selected from phage library screening. MRM quantification of EVs proteins can also help in identifying those that are subpopulation specific markers for further target-specific isolation.

Extracellular Vesicle-Based Therapy for COVID-19: Promises, Challenges and Future Prospects

The COVID-19 pandemic has become a serious concern and has negatively impacted public health and the economy. It primarily targets the lungs, causing acute respiratory distress syndrome (ARDS); however, it may also lead to multiple organ failure (MOF) and enhanced mortality rates. Hence, there is an urgent need to develop potential effective therapeutic strategies for COVID-19 patients. Extracellular vesicles (EVs) are released from various types of cells that participate in intercellular communication to maintain physiological and pathological processes. EVs derived from various cellular origins have revealed suppressive effects on the cytokine storm during systemic hyper-inflammatory states of severe COVID-19, leading to enhanced alveolar fluid clearance, promoted epithelial and endothelial recovery, and cell proliferation. Being the smallest subclass of EVs, exosomes offer striking characteristics such as cell targeting, being nano-carriers for drug delivery, high biocompatibility, safety, and low-immunogenicity, thus rendering them a potential cell-free therapeutic candidate against the pathogeneses of various diseases. Due to these properties, numerous studies and clinical trials have been performed to assess their safety and therapeutic efficacy against COVID-19. Hence, in this review, we have comprehensively described current updates on progress and challenges for EVs as a potential therapeutic agent for the management of COVID-19.

Extracellular Vesicles as Therapeutic Tools for the Treatment of Chronic Wounds

Chronic wounds develop when the orderly process of cutaneous wound healing is delayed or disrupted. Development of a chronic wound is associated with significant morbidity and financial burden to the individual and health-care system. Therefore, new therapeutic modalities are needed to address this serious condition. Mesenchymal stem cells (MSCs) promote skin repair, but their clinical use has been limited due to technical challenges. Extracellular vesicles (EVs) are particles released by cells that carry bioactive molecules (lipids, proteins, and nucleic acids) and regulate intercellular communication. EVs (exosomes, microvesicles, and apoptotic bodies) mediate key therapeutic effects of MSCs. In this review we examine the experimental data establishing a role for EVs in wound healing. Then, we explore techniques for designing EVs to function as a targeted drug delivery system and how EVs can be incorporated into biomaterials to produce a personalized wound dressing. Finally, we discuss the status of clinically deploying EVs as a therapeutic agent in wound care.

Characterization and Therapeutic Use of Extracellular Vesicles Derived from Platelets

Autologous blood products, such as platelet-rich plasma (PRP), are gaining increasing interest in different fields of regenerative medicine. Although growth factors, the main components of PRP, are thought to stimulate reparation processes, the exact mechanism of action and main effectors of PRP are not fully understood. Plasma contains a high amount of extracellular vesicles (EVs) produced by different cells, including anucleated platelets. Platelet-derived EVs (PL-EVs) are the most abundant type of EVs in circulation. Numerous advantages of PL-EVs, including their ability to be released locally, their ease of travel through the body, their low immunogenicity and tumourigenicity, the modulation of signal transduction as well as the ease with which they can be obtained, has attracted increased attention n. This review focuses briefly on the biological characteristics and isolation methods of PL-EVs, including exosomes derived from platelets (PL-EXOs), and their involvement in the pathology of diseases. Evidence that shows how PL-EVs can be used as a novel tool in medicine, particularly in therapeutic and regenerative medicine, is also discussed in this review.

Zebrafish as a preclinical model for Extracellular Vesicle-based therapeutic development

Extracellular Vesicles (EVs) are released during various pathophysiological processes and reflect the state of their cell of origin. Once released, they can propagate through biological fluids, target cells, deliver their content and elicit functional responses. These specific features would allow their harnessing as biomarkers, drug nano-vehicles and therapeutic intrinsic modulators. However, the further development of their potential therapeutic application is hampered by the lack of knowledge about how EVs behave in vivo. Recent advances in the field of imaging EVs in vivo now allow live-tracking of endogenous and exogenous EV in various model organisms at high spatiotemporal resolution to define their distribution, half-life and fate. This review highlights current imaging tools available to image EVs in vivo and how live imaging especially in the zebrafish embryo can bring further insights into the characterization of EVs dynamics, biodistribution and functions to potentiate their development for therapeutic applications.

Adipose-derived stromal/stem cells and extracellular vesicles for cancer therapy

INTRODUCTION

Mesenchymal stromal/stem cells (MSCs) hold great perspective for the therapy of a host of diseases due to regenerative and anti-inflammatory properties by differentiation into diverse cell populations, homing to damaged tissue regions, paracrine effects, and release of extracellular vesicles.

AREAS COVERED

This review describes the isolation, characterization, and potential use of MSCs and ADSCs for benign and malignant diseases. The MSCs may be administered as whole cells or in form of their secretome that is held responsible for most of their beneficial effects. A special constituent of the paracrine components are the extracellular vesicles (EVs) that carry a biologically potent cargo of proteins, cytokines, and RNA.

EXPERT OPINION

The applications of MSCs and ADSCs are amply documented and have been investigated in preclinical models and many unregulated and a few controlled trials. Larger numbers of MSCs and ADSCs can be obtained for allogeneic transfer but imply difficulties including perseverance of the cells in vivo and possible differentiation into harmful cell types. MSC-derived cell-free preparations are easier to handle and manufacture for various applications. Especially, with the help of bioreactors, EVs can be obtained in excessive numbers and preloaded or charged with proteins, cytokines, and regulatory RNA specimen to treat inflammatory diseases and cancer.

Exosomes contribution in COVID-19 patients' treatment

Adipose cell-free derivatives have been recently gaining attention as potential therapeutic agents for various human diseases. In this context, mesenchymal stromal/stem cells (MSCs), adipocyte mesenchymal stem cells (Ad-MSCs) and adipose-derived stem cells (ADSC) possessing potent immunomodulatory activities are proposed as a therapeutic option for the treatment of coronavirus disease 2019 (COVID-19). The COVID-19 represents a global concern of public health caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in which there is not actually any specific therapy. MSCs exert an immunomodulation effect due to the secretion of endogenous factors, such as vascular endothelial growth factor (VEGF), insulin growth factor (IGF), and nerve growth factor (NGF), transforming growth factor (TGF)-β and growth differentiation factor (GDF)-11. Recent reports are promising for further studies and clinical applications of ADSCs and Ad-MSCs in COVID-19 patients. Experimental and clinical studies are exploring the therapeutic potential of both MSCs and derived-exosomes in moderating the morbidity and mortality of COVID-19. In this field, more preclinical and clinical studies are warranted to find an effective treatment for the patients suffering from COVID-19 infection.

Human umbilical cord-derived mesenchymal stem cells improve chronic pancreatitis in rats via the AKT-mTOR-S6K1 signaling pathway

Chronic pancreatitis (CP) is a progressive inflammatory disease. In clinical treatment, many patients cannot get a timely diagnosis and effective treatment due to the lack of early diagnosis indicators. Mesenchymal stem cells have immunomodulatory and anti-inflammatory effects, and have broad application prospects in treating auto-immune diseases and inflammatory diseases. This study aimed to clarify the mechanisms of human umbilical cord mesenchymal stem cells (HUCMSCs) in the treatment of CP. The rats were randomly divided into four groups, with six rats in each group: control group, CP group, CP + HUCMSCs-treated group I, and CP + HUCMSCs-treated group II. We evaluated the levels of inflammatory factors, fibrosis and apoptosis markers, detected the protein expression levels of AKT-mTOR-S6K1 and assessed histological changes of the pancreas. The results showed that HUCMSCs not only inhibited the secretion of inflammatory cytokines and activation of pancreatic stellate cells but also suppressed the apoptosis of acinar cells. Further investigation revealed that HUCMSCs noticeably suppressed the AKT-mTOR-S6K1 pathway in the pancreatic tissue of DBTC-induced CP. In addition, the therapeutic effect of HUCMSCs injected into the inferior vena cava and left gastric artery in the CP model was also observed, thus providing the basis for the clinical application of intervention measures.

Extracellular Vesicle-Based Therapeutics for Heart Repair

Extracellular vesicles (EVs) are constituted by a group of heterogeneous membrane vesicles secreted by most cell types that play a crucial role in cell–cell communication. In recent years, EVs have been postulated as a relevant novel therapeutic option for cardiovascular diseases, including myocardial infarction (MI), partially outperforming cell therapy. EVs may present several desirable features, such as no tumorigenicity, low immunogenic potential, high stability, and fine cardiac reparative efficacy. Furthermore, the natural origin of EVs makes them exceptional vehicles for drug delivery. EVs may overcome many of the limitations associated with current drug delivery systems (DDS), as they can travel long distances in body fluids, cross biological barriers, and deliver their cargo to recipient cells, among others. Here, we provide an overview of the most recent discoveries regarding the therapeutic potential of EVs for addressing cardiac damage after MI. In addition, we review the use of bioengineered EVs for targeted cardiac delivery and present some recent advances for exploiting EVs as DDS. Finally, we also discuss some of the most crucial aspects that should be addressed before a widespread translation to the clinical arena.

Skin Immunomodulation during Regeneration: Emerging New Targets

Adipose-Derived Stem Cells (ADSC) are present within the hypodermis and are also expected to play a pivotal role in wound healing, immunomodulation, and rejuvenation activities. They orchestrate, through their exosome, the mechanisms associated to cell differentiation, proliferation, and cell migration by upregulating genes implicated in different functions including skin barrier, immunomodulation, cell proliferation, and epidermal regeneration. ADSCs directly interact with their microenvironment and specifically the immune cells, including macrophages and T and B cells, resulting in differential inflammatory and anti-inflammatory mechanisms impacting, in return, ADSCs microenvironment and thus skin function. These useful features of ADSCs are involved in tissue repair, where the required cell proliferation, angiogenesis, and anti-inflammatory responses should occur rapidly in damaged sites. Different pathways involved have been reported such as Growth Differentiation Factor-11 (GDF11), Tumor Growth Factor (TGF)-β, Metalloproteinase (MMP), microRNA, and inflammatory cytokines that might serve as specific biomarkers of their immunomodulating capacity. In this review, we try to highlight ADSCs’ network and explore the potential indicators of their immunomodulatory effect in skin regeneration and aging. Assessment of these biomarkers might be useful and should be considered when designing new clinical therapies using ADSCs or their specific exosomes focusing on their immunomodulation activity.

Exosomes as Drug Delivery Systems: Endogenous Nanovehicles for Treatment of Systemic Lupus Erythematosus

Exosomes, nanometer-sized lipid-bilayer-enclosed extracellular vesicles (EVs), have attracted increasing attention due to their inherent ability to shuttle proteins, lipids and genes between cells and their natural affinity to target cells. Their intrinsic features such as stability, biocompatibility, low immunogenicity and ability to overcome biological barriers, have prompted interest in using exosomes as drug delivery vehicles, especially for gene therapy. Evidence indicates that exosomes play roles in both immune stimulation and tolerance, regulating immune signaling and inflammation. To date, exosome-based nanocarriers delivering small molecule drugs have been developed to treat many prevalent autoimmune diseases. This review highlights the key features of exosomes as drug delivery vehicles, such as therapeutic cargo, use of targeting peptide, loading method and administration route with a broad focus. In addition, we outline the current state of evidence in the field of exosome-based drug delivery systems in systemic lupus erythematosus (SLE), evaluating exosomes derived from various cell types and engineered exosomes.

An Overview of Exosomes in Cancer Therapy: A Small Solution to a Big Problem

Exosomes are defined as a type of extracellular vesicle released when multivesicular bodies of the endocytic pathway fuse with the plasma membrane. They are characterized by their role in extracellular communication, partly due to their composition, and present the ability to recognize and interact with cells from the immune system, enabling an immune response. Their targeting capability and nanosized dimensions make them great candidates for cancer therapy. As chemotherapy is associated with cytotoxicity and multiple drug resistance, the use of exosomes targeting capabilities, able to deliver anticancer drugs specifically to cancer cells, is a great approach to overcome these disadvantages. The objective is to assess treatment efficiency in reducing tumor cells, as well as overall safety and response by cancer carriers. So far, results show exosomes as a promising therapeutic strategy in the fight against cancer. This review summarizes the characteristics and composition of exosomes, as well as explaining in detail the involved parties in the origin of exosomes. Furthermore, some considerations about exosome application in immunotherapy are addressed. The main isolation and loading methods are described to give an insight into how exosomes can be obtained and manipulated. Finally, some therapeutic applications of exosomes in cancer therapy are described.