Exosome as a Novel Shuttle for Delivery of Therapeutics across Biological Barriers

High frequency acoustic cell stimulation promotes exosome generation regulated by a calcium-dependent mechanism

Exosomes are promising disease diagnostic markers and drug delivery vehicles, although their use in practice is limited by insufficient homogeneous quantities that can be produced. We reveal that exposing cells to high frequency acoustic irradiation stimulates their generation without detriment to cell viability by exploiting their innate membrane repair mechanism, wherein the enhanced recruitment of calcium ions from the extracellular milieu into the cells triggers an ESCRT pathway known to orchestrate exosomal production. Given the high post-irradiation cell viabilities (≈95%), we are able to recycle the cells through iterative irradiation and post-excitation incubation steps, which facilitate high throughput production of a homogeneous population of exosomes-a particular challenge for translating exosome therapy into clinical practice. In particular, we show that approximately eight- to ten-fold enrichment in the number of exosomes produced can be achieved with just 7 cycles over 280 mins, equivalent to a yield of around 1.7-2.1-fold/h.

Extracellular Vesicles - Advanced Nanocarriers in Cancer Therapy: Progress and Achievements

Extracellular vesicles (EVs) are a class of cell-derived, lipid bilayer membrane composed vesicles, and some of them such as exosomes and ectosomes have been proven, playing remarkable roles in transmitting intercellular information, and being involved in each property of cell physiological activities. Nowadays, EVs are considered as potential nanocarriers which could partially resolve the problems of current chemotherapy because of their distinctive advantages. As endogenous membrane encompassed vesicles with nanosize, EVs are able to pass through the natural barriers with prolonged circulation time in vivo and have intrinsic cell targeting properties, they are less toxic, and less immunogenic. Recently, studies focusing on EV-based drug delivery system for cancer therapy have exploded dramatically. This review aims to outline the current applications of EVs as potential nanosized drug carriers in cancer therapy. Firstly, the characteristics and biofunctions of each EV subtype are described. Then the variety of therapeutic cargoes, the loading methods, and the targeting strategy of engineered EVs are emphatically introduced. Thereafter the pros and cons of EVs applied as therapeutic carriers, as well as the future prospects in this field, are discussed.

Cell-Free Extracellular Vesicles Derived from Human Bone Marrow Endothelial Progenitor Cells as Potential Therapeutics for Microvascular Endothelium Restoration in ALS

Repairing the damaged blood-CNS-barrier in amyotrophic lateral sclerosis (ALS) is necessary to prevent entry of detrimental blood-borne factors contributing to motor neuron dysfunction. Recently, we showed benefits of human bone marrow endothelial progenitor cell (hBM-EPC) transplantation into symptomatic ALS mice on barrier restoration by replacing damaged endothelial cells (ECs). Additionally, transplanted cells may endogenously repair ECs by secreting angiogenic factors as our subsequent in vitro study demonstrated. Based on these study results, hBM-EPCs may secrete extracellular vesicles, which may contain and transfer diverse vesicular biomolecules towards maintenance of EC functionality. The study aimed to characterize extracellular vesicles (EVs) derived from hBM-EPCs as potential cell-free therapeutics for endothelium repair in ALS. EVs were isolated from hBM-EPC media at different culture times and vesicle properties were evaluated. The protective effects of EVs on mouse brain endothelial cells (mBECs) exposed to ALS mouse plasma were investigated. Uptake and blockage of EVs from GFP-transfected hBM-EPCs in ECs were determined in vitro. Results showed that EVs isolated from hBM-EPCs as nanosized vesicles significantly reduced mBEC damage from the pathological environment and these EVs were taken up by cells. Blockage of β1 integrin on EVs prevented internalization of vesicles in mBECs. Together, these results provide evidence for potential of hBM-EPC-derived EVs as novel cell-free therapeutics for repair of endothelium in ALS. Although determining translational potential of hBM-EPC-derived EVs will require evaluation in vivo, this in vitro study represents a step towards an extracellular vesicle-based approach for repair of the damaged microvascular endothelium in ALS.

Cancer associated fibroblast mediated chemoresistance: A paradigm shift in understanding the mechanism of tumor progression

One of the undeniable issues with cancer eradication is the evolution of chemoresistance in due course of treatment, and the mechanisms of chemoresistance have been the subject of extensive research for several years. The efficacy of chemotherapy is hindered by cancer epithelium, mostly in a cell-autonomous mechanism. However, recently the valid experimental evidence showed that the surrounding tumor microenvironment (TME) is equivalently responsible for the induction of chemoresistance. Of the verities of cells in the tumor microenvironment, cancer-associated fibroblasts (CAFs) are the major cellular component of TME and act as a key regulator in the acquisition of cancer chemoresistance by providing a protective niche to the cancer cells against the anti-cancer drugs. Moreover, the symbiotic relationship between the tumor and CAFs to obtain key resources such as growth factors and nutrients for optimal tumor growth and proliferation favors the chemoresistance phenotype. Here, in this review, we provide an up-to-date overview of our knowledge of the role of the CAFs in inducing chemoresistance and tumor progression. We also further delineated the emerging events leading to the CAF origins and activation of normal fibroblasts to CAFs. Along with this, we also discuss the novel area of research confined to the CAF targeted therapies of cancer. The identification of CAF-specific markers may allow unveiling new targets and avenues for blunting or reverting the detrimental pro-tumorigenic potential of CAFs in the foreseeable future.

Towards analyzing the potential of exosomes to deliver microRNA therapeutics

Exosome selectivity mechanisms underlying exosome-target cell interactions and the specific traits affecting their capability to communicate still remain unclear. Moreover, the capacity of exosomes to efficiently deliver their molecular cargos intracellularly needs precise investigation towards establishing functional exosome-based delivery platforms exploitable in the clinical practice. The current study focuses on: (a) exosome production from normal MRC-5 and Vero cells growing in culture, (b) physicochemical characterization by dynamic light scattering (DLS) and cryo-transmission electron microscopy; (c) cellular uptake studies of rhodamine-labeled exosomes in normal and cancer cells, providing to exosomes either "autologous" or "heterologous" cellular delivery environments; and (d) loading exogenous Alexa Fluor 488-labeled siRNA into exosomes for the assessment of their delivering capacity by immunofluorescence in a panel of recipient cells. The data obtained thus far indicate that MRC-5 and Vero exosomes, indeed exhibit an interesting delivering profile, as promising "bio-shuttles," being pharmacologically exploitable in the context of theranostic applications.

Extracellular Vesicles-Based Drug Delivery Systems: A New Challenge and the Exemplum of Malignant Pleural Mesothelioma

Research for the most selective drug delivery to tumors represents a fascinating key target in science. Alongside the artificial delivery systems identified in the last decades (e.g., liposomes), a family of natural extracellular vesicles (EVs) has gained increasing focus for their potential use in delivering anticancer compounds. EVs are released by all cell types to mediate cell-to-cell communication both at the paracrine and the systemic levels, suggesting a role for them as an ideal nano-delivery system. Malignant pleural mesothelioma (MPM) stands out among currently untreatable tumors, also due to the difficulties in achieving an early diagnosis. Thus, early diagnosis and treatment of MPM are both unmet clinical needs. This review looks at indirect and direct evidence that EVs may represent both a new tool for allowing an early diagnosis of MPM and a potential new delivery system for more efficient therapeutic strategies. Since MPM is a relatively rare malignant tumor and preclinical MPM models developed to date are very few and not reliable, this review will report data obtained in other tumor types, suggesting the potential use of EVs in mesothelioma patients as well.

Exosomes: From garbage bins to translational medicine

Exosomes are lipid bilayer-enclosed vesicles of endosomal origin, which initially considered as garbage bins to dispose unwanted cellular components, but they are now emerged as an intercellular communication system involved in several physiological and pathological conditions. With the increasing understanding that the healthy patients release exosomes with distinct proteins and RNAs, exosomes have been exploited as biomarkers for disease diagnosis and prognosis. Owing to the intrinsic immunomodulatory in a tumor microenvironment, exosomes have also been vaccinated into patients against malignant diseases. Moreover, the nano-metered exosomes are relatively stable in extracellular fluids. Thus they appear attractive in delivering "cargo" to destined cells with enhanced efficiency. In this review, we outline the current knowledge in exosomal biogenesis and isolation. Furthermore, the biological activities of exosomes are also discussed with a focus on their potentials to be employed in translational medicine, especially as biomarkers, vaccines and therapeutic delivery system.

LncRNA PVT1 promotes exosome secretion through YKT6, RAB7, and VAMP3 in pancreatic cancer

Pancreatic cancer (PC) is one of the deadliest cancers worldwide. Cancer cells secrete excessive numbers of exosomes that play essential roles in tumorigenesis. Long non-coding RNAs (lncRNAs) are essential non-coding RNAs for cancer progression. However, the role of lncRNA plasmacytoma variant translocation 1 (PVT1) in exosome secretion of PC remains to be comprehensively investigated. Thus, nanoparticle tracking analysis and transmission electron microscopy were performed to determine exosome secretion. Confocal microscopy, western blots, real-time PCR, immunofluorescence, pull-down and RNA immunoprecipitation assays, and rescue experiments were applied to investigate the mechanism underlying the role of PVT1 in exosome secretion. The results showed that PVT1 was upregulated in PC cells, along with increased levels of YKT6 v-SNARE homolog (YKT6), ras-related protein Rab-7 (RAB7), and vesicle-associated membrane protein 3 (VAMP3). Also, PVT1 promoted the transportation of multivesicular bodies (MVBs) towards the plasma membrane. In addition, PVT1 promoted the docking of MVBs by altering RAB7 expression and localization. Moreover, PVT1 promoted the fusion of MVBs with the plasma membrane through regulating YKT6 and VAMP3 colocalization and the palmitoylation of YKT6. Taken together, the results suggest that PVT1 promoted exosome secretion of PC cells and thus, can expand the understanding of PVT1 in tumor biology.

Bacterial outer membrane vesicles as a platform for biomedical applications: An update

Outer membrane vesicles (OMVs) are produced by Gram-negative bacteria both in vitro and in vivo. OMVs are nano-sized spherical vehicles formed by lipid bilayer membranes and contain multiple parent bacteria-derived components. Based on the presence of bacterial antigens, pathogen-associated molecular patterns (PAMPs), adhesins, various proteins and the vesicle structure, OMVs have been developed for biomedical applications as bacterial vaccines, adjuvants, cancer immunotherapy agents, drug delivery vehicles, and anti-bacteria adhesion agents. In this review, we analyze the contributions of the structure and composition of OMVs to their applications, summarize the methods used to isolate and characterize OMVs, and highlight recent progress and future perspectives of OMVs in biomedical applications.

Exosome Derived from Coronary Serum of Patients with Myocardial Infarction Promotes Angiogenesis Through the miRNA-143/IGF-IR Pathway

Purpose

Myocardial ischemia-reperfusion injury primarily causes myocardial infarction (MI), which is manifested by cell death. Angiogenesis is essential for repair and regeneration in cardiac tissue after MI. In this study, we aimed to investigate the effect of exosomes derived from the serum of MI patients in angiogenesis and its related mechanism.

Patients and Methods

Exosomes, isolated from serum, were collected from MI (MI-exosome) and control (Con-exosome) patients. After coculturing with human umbilical vein endothelial cells, MI-exosome promoted cell proliferation, migration, and tube formation.

Results

The results revealed that the production and release of MI-exosome were associated with cardiomyocytes. Moreover, microarray assays demonstrated that miRNA-143 was significantly decreased in MI-exosome. Meanwhile, the overexpression and knockdown of miRNA-143 could inhibit and enhance angiogenesis, respectively. Furthermore, the effect of exosomal miRNA-143 on angiogenesis was mediated by its targeting gene, insulin-like growth factor 1 receptor (IGF-IR), and was associated with the production of nitric oxide (NO).

Conclusion

Taken together, exosomes derived from the serum of patients with MI promoted angiogenesis through the IGF-IR/NO signaling pathway. The results provide novel understanding of the function of exosomes in MI.

Approaches to inducing antigen-specific immune tolerance in allergy and autoimmunity: Focus on antigen-presenting cells and extracellular vesicles

Increasing prevalence of allergic and autoimmune diseases urges clinicians and researchers to search for new and efficient treatments. Strategies that activate antigen-specific immune tolerance and simultaneously maintain immune reactivity to all other antigens deserve special attention. Accordingly, antigen-presenting cells (APCs) seem to be the best suited for orchestrating these mechanisms by directing T cell immune responses towards a tolerant subtype. Recent advances in understanding cell-to-cell communication via extracellular vesicles (EVs) make the latter promising candidates for reprogramming APCs towards a tolerant phenotype, and for mediating tolerogenic APC function. Thus, comprehensive studies have been undertaken to describe the interactions of APCs and EVs naturally occurring during immune tolerance induction, as well as to develop EV-based manoeuvres enabling the induction of immune tolerance in an antigen-specific manner. In this review, we summarize the findings of relevant studies, with a special emphasis on future perspectives on their translation to clinical practice.

Extracellular vesicles in urological malignancies: an update

Extracellular vesicles (EVs) have an essential functional role in local tumour progression, metastatic spread and the emergence of drug resistance in bladder, kidney and prostate cancer. Thus, EVs could be diagnostic, prognostic and predictive biomarkers for these malignancies. Virtually all biomolecules (including DNA, mRNA, microRNA, long non-coding RNA, proteins and lipids) packaged into EVs have been tested as biomarkers in blood and urine samples. The results are very heterogeneous, but promising biomarker candidates have been identified. Differing methods of EV isolation, characterization and analysis of their content have been used owing to a lack of international consensus; hence, comparing study results is challenging. Furthermore, validation of potential biomarkers in independent cohorts or prospective trials has rarely been performed. Future efforts to establish EV-derived biomarkers need to adequately address these points. In addition, emerging technologies such as mass spectroscopy and chip-based approaches can identify surface markers specific for cancer-associated EVs and will enable specific separation from blood and urine EVs, which probably will improve their performance as biomarkers. Moreover, EVs could be harnessed as therapeutic drug delivery vehicles for precise and effective anticancer therapy.

Noninvasive Assessment of Exosome Pharmacokinetics In Vivo: A Review

Exosomes, intraluminal vesicles that contain informative DNA, RNA, proteins, and lipid membranes derived from the original donor cells, have recently been introduced to therapy and diagnosis. With their emergence as an alternative to cell therapy and having undergone clinical trials, proper analytical standards for evaluating their pharmacokinetics must now be established. Molecular imaging techniques such as fluorescence imaging, magnetic resonance imaging, and positron emission tomography (PET) are helpful to visualizing the absorption, distribution, metabolism, and excretion of exosomes. After exosomes labelled with a fluorescer or radioisotope are administered in vivo, they are differentially distributed according to the characteristics of each tissue or lesion, and real-time biodistribution of exosomes can be noninvasively monitored. Quantitative analysis of exosome concentration in biological fluid or tissue samples is also needed for the clinical application and industrialization of exosomes. In this review, we will discuss recent pharmacokinetic applications to exosomes, including labelling methods for in vivo imaging and analytical methods for quantifying exosomes, which will be helpful for evaluating pharmacokinetics of exosomes and improving exosome development and therapy.

Exploring the key communicator role of exosomes in cancer microenvironment through proteomics

There have been many attempts to fully understand the mechanism of cancer behavior. Yet, how cancers develop and metastasize still remain elusive. Emerging concepts of cancer biology in recent years have focused on the communication of cancer with its microenvironment, since cancer cannot grow and live alone. Cancer needs to communicate with other cells for survival, and thus they secrete various messengers, including exosomes that contain many proteins, miRNAs, mRNAs, etc., for construction of the tumor microenvironment. Moreover, these intercellular communications between cancer and its microenvironment, including stromal cells or distant cells, can promote tumor growth, metastasis, and escape from immune surveillance. In this review, we summarized the role of proteins in the exosome as communicators between cancer and its microenvironment. Consequently, we present cancer specific exosome proteins and their unique roles in the interaction between cancer and its microenvironment. Clinically, these exosomes might provide useful biomarkers for cancer diagnosis and therapeutic tools for cancer treatment.

Biomimetic and bioinspired strategies for oral drug delivery

Oral drug delivery remains the most preferred approach due to its multiple advantages. Recently there has been increasing interest in the development of advanced vehicles for oral delivery of different therapeutics. Among them, biomimetic and bioinspired strategies are emerging as novel approaches that are promising for addressing biological barriers encountered by traditional drug delivery systems. Herein we provide a state-of-the-art review on the current progress of biomimetic particulate oral delivery systems. Different biomimetic nanoparticles used for oral drug delivery are first discussed, mainly including ligand/antibody-functionalized nanoparticles, transporter-mediated nanoplatforms, and nanoscale extracellular vesicles. Then we describe bacteria-derived biomimetic systems, with respect to oral delivery of therapeutic proteins or antigens. Subsequently, yeast-derived oral delivery systems, based on either chemical engineering or bioengineering approaches are discussed, with emphasis on the treatment of inflammatory diseases and cancer as well as oral vaccination. Finally, bioengineered plant cells are introduced for oral delivery of biological agents. A future perspective is also provided to highlight the existing challenges and possible resolution toward clinical translation of currently developed biomimetic oral therapies.

Porcine Milk Exosome MiRNAs Attenuate LPS-Induced Apoptosis through Inhibiting TLR4/NF-κB and p53 Pathways in Intestinal Epithelial Cells

Lipopolysaccharide (LPS) is a bacterial endotoxin that induces intestine inflammation. Milk exosomes improve the intestine and immune system development of newborns. This study aims to establish the protective mechanisms of porcine milk exosomes on the attenuation of LPS-induced intestinal inflammation and apoptosis. In vivo, exosomes prevented LPS-induced intestine damage and inhibited (p < 0.05) LPS-induced inflammation. In vitro, exosomes inhibited (p < 0.05) LPS-induced intestinal epithelial cells apoptosis (23% ± 0.4% to 12% ± 0.2%). Porcine milk exosomes also decreased (p < 0.05) the LPS-induced TLR4/NF-κB signaling pathway activation. Furthermore, exosome miR-4334 and miR-219 reduced (p < 0.05) LPS-induced inflammation through the NF-κB pathway and miR-338 inhibited (p < 0.05) the LPS-induced apoptosis via the p53 pathway. Cotransfection with these three miRNAs more effectively prevented (p < 0.05) LPS-induced cell apoptosis than these miRNAs individual transfection. The apoptosis percentage in the group cotransfected with the three miRNAs (14% ± 0.4%) was lower (p < 0.05) than that in the NC miRNA group (28% ± 0.5%), and also lower than that in each individual miRNA group. In conclusion, porcine milk exosomes protect the intestine epithelial cells against LPS-induced injury by inhibiting cell inflammation and protecting against apoptosis through the action of exosome miRNAs. The presented results suggest that the physiological amounts of miRNAs-enriched exosomes addition to infant formula could be used as a novel preventative measure for necrotizing enterocolitis.

Pro-survival autophagy: An emerging candidate of tumor progression through maintaining hallmarks of cancer

Autophagy is an evolutionary conserved catabolic process that regulates the cellular homeostasis by targeting damaged cellular contents and organelles for lysosomal degradation and sustains genomic integrity, cellular metabolism, and cell survival during diverse stress and adverse conditions. Recently, the role of autophagy is extremely debated in the regulation of cancer initiation and progression. Although autophagy has a dichotomous role in the regulation of cancer, growing numbers of studies largely indicate the pro-survival role of autophagy in cancer progression and metastasis. In this review, we discuss the detailed mechanisms of autophagy, the role of pro-survival autophagy that positively drives several classical as well as emerging hallmarks of cancer for tumorigenic progression, and also we address various autophagy inhibitors that could be harnessed against pro-survival autophagy for effective cancer therapeutics. Finally, we highlight some outstanding problems that need to be deciphered extensively in the future to unravel the role of autophagy in tumor progression.

Exosome release and cargo in Down syndrome

Down syndrome (DS) is a multisystem disorder affecting 1 in 800 births worldwide. Advancing technology, medical treatment, and social intervention have dramatically increased life expectancy, yet there are many etiologies of this disorder that are in need of further research. The advent of the ability to capture extracellular vesicles (EVs) in blood from specific cell types allows for the investigation of novel intracellular processes. Exosomes are one type of EVs that have demonstrated great potential in uncovering new biomarkers of neurodegeneration and disease, and also that appear to be intricately involved in the transsynaptic spread of pathogenic factors underlying Alzheimer's disease and other neurological diseases. Exosomes are nanosized vesicles, generated in endosomal multivesicular bodies (MVBs) and secreted by most cells in the body. Since exosomes are important mediators of intercellular communication and genetic exchange, they have emerged as a major research focus and have revealed novel biological sequelae involved in conditions afflicting the DS population. This review summarizes current knowledge on exosome biology in individuals with DS, both early in life and in aging individuals. Collectively these studies have demonstrated that complex multicellular processes underlying DS etiologies may include abnormal formation and secretion of extracellular vesicles such as exosomes.

Physiologic constraints of using exosomes in vivo as systemic delivery vehicles

Systemic delivery of exosomes meets hurdles which had not been elucidated using live molecular imaging for their biodistribution. Production and uptake of endogenous exosomes are expected to be nonspecific and specific, respectively, where external stimuli of production of exosomes and their quantitative degree of productions are not understood. Despite this lack of understanding of basic physiology of in vivo behavior of exosomes including their possible paracrine or endocrine actions, many engineering efforts are taken to develop therapeutic vehicles. Especially, the fraction of exosomes’ taking the routes of waste disposal and exerting target actions are not characterized after systemic administration. Here, we reviewed the literature about in vivo distribution and disposal/excretion of exogenous or endogenous exosomes and, from these limited resources of knowledge currently available, summarized the knowledge and the uncertainties of exosomes on physiologic standpoints. An eloquent example of the investigations to understand the roles and confounders of exosomes’ action in the brain was highlighted with emphasis on the recent discovery of brain lymphatics and hypothesis of glymphatic/lymphatic clearance pathways in diseases as well as in physiologic processes. The possibility of delivering therapeutic exosomes through the systemic circulation, across blood-brain barriers and finally to target cells such as microglia, astrocytes and/or neurons is a good testbed in which the investigators can formulate problems to solve for both understanding (science) and application (engineering).

Exosomes as Drug Carriers for Cancer Therapy

Exosomes, biological extracellular vesicles, have recently begun to find use in targeted drug delivery in solid tumor research. Ranging from 30-120 nm in size, exosomes are secreted from cells and isolated from bodily fluids. Exosomes provide a unique material platform due to their characteristics, including physical properties such as stability, biocompatibility, permeability, low toxicity, and low immunogenicity-all critical to the success of any nanoparticle drug delivery system. In addition to traditional chemotherapeutics, natural products and RNA have been encapsulated for the treatment of breast, pancreatic, lung, prostate cancers, and glioblastoma. This review discusses current research on exosomes for drug delivery to solid tumors.

Extracellular vesicles, news about their role in immune cells: physiology, pathology and diseases

Two types of extracellular vesicles (EVs), exosomes and ectosomes, are generated and released by all cells, including immune cells. The two EVs appear different in many properties: size, mechanism and site of assembly, composition of their membranes and luminal cargoes, sites and processes of release. In functional terms, however, these differences are minor. Moreover, their binding to and effects on target cells appear similar, thus the two types are considered distinct only in a few cases, otherwise they are presented together as EVs. The EV physiology of the various immune cells differs as expected from their differential properties. Some properties, however, are common: EV release, taking place already at rest, is greatly increased upon cell stimulation; extracellular navigation occurs adjacent and at distance from the releasing cells; binding to and uptake by target cells are specific. EVs received from other immune or distinct cells govern many functions in target cells. Immune diseases in which EVs play multiple, often opposite (aggression and protection) effects, are numerous; inflammatory diseases; pathologies of various tissues; and brain diseases, such as multiple sclerosis. EVs also have effects on interactive immune and cancer cells. These effects are often distinct, promoting cytotoxicity or proliferation, the latter together with metastasis and angiogenesis. Diagnoses depend on the identification of EV biomarkers; therapies on various mechanisms such as (1) removal of aggression-inducing EVs; (2) EV manipulations specific for single targets, with insertion of surface peptides or luminal miRNAs; and (3) removal or re-expression of molecules from target cells.