Exosomes as Reconfigurable Therapeutic Systems

Perspectives on Directions and Priorities for Future Preclinical Studies in Regenerative Medicine

The myocardium consists of numerous cell types embedded in organized layers of ECM (extracellular matrix) and requires an intricate network of blood and lymphatic vessels and nerves to provide nutrients and electrical coupling to the cells. Although much of the focus has been on cardiomyocytes, these cells make up <40% of cells within a healthy adult heart. Therefore, repairing or regenerating cardiac tissue by merely reconstituting cardiomyocytes is a simplistic and ineffective approach. In fact, when an injury occurs, cardiac tissue organization is disrupted at the level of the cells, the tissue architecture, and the coordinated interaction among the cells. Thus, reconstitution of a functional tissue must reestablish electrical and mechanical communication between cardiomyocytes and restore their surrounding environment. It is also essential to restore distinctive myocardial features, such as vascular patency and pump function. In this article, we review the current status, challenges, and future priorities in cardiac regenerative or reparative medicine. In the first part, we provide an overview of our current understanding of heart repair and comment on the main contributors and mechanisms involved in innate regeneration. A brief section is dedicated to the novel concept of rejuvenation or regeneration, which we think may impact future development in the field. The last section describes regenerative therapies, where the most advanced and disruptive strategies used for myocardial repair are discussed. Our recommendations for priority areas in studies of cardiac regeneration or repair are summarized in Tables 1 and 2 .

Activated Human Lung Fibroblasts Produce Extracellular Vesicles with Antifibrotic Prostaglandins

The differentiation of interstitial lung fibroblasts into contractile myofibroblasts that proliferate and secrete excessive extracellular matrix is critical for the pathogenesis of pulmonary fibrosis. Certain lipid signaling molecules, such as prostaglandins (PGs), can inhibit myofibroblast differentiation. However, the sources and delivery mechanisms of endogenous PGs are undefined. Activated primary human lung fibroblasts (HLFs) produce PGs such as PGE₂. We report that activation of primary HLFs with IL-1β inhibited transforming growth factor β-induced myofibroblast differentiation in both the IL-1β-treated cells themselves (autocrine signal) and adjacent naive HLFs in cocultures (paracrine signal). Additionally, we demonstrate for the first time that at least some of the antifibrotic effect of activated fibroblasts on nearby naive fibroblasts is carried by exosomes and other extracellular vesicles that contain several PGs, including high levels of the antifibrotic PGE₂. Thus, activated fibroblasts communicate with surrounding cells to limit myofibroblast differentiation and maintain homeostasis. This work opens the way for future research into extracellular vesicle-mediated intercellular signaling in the lung and may inform the development of novel therapies for fibrotic lung diseases.

Adipogenesis and metabolic health

Obesity is characterized by increased adipose tissue mass and has been associated with a strong predisposition towards metabolic diseases and cancer. Thus, it constitutes a public health issue of major proportion. The expansion of adipose depots can be driven either by the increase in adipocyte size (hypertrophy) or by the formation of new adipocytes from precursor differentiation in the process of adipogenesis (hyperplasia). Notably, adipocyte expansion through adipogenesis can offset the negative metabolic effects of obesity, and the mechanisms and regulators of this adaptive process are now emerging. Over the past several years, we have learned a considerable amount about how adipocyte fate is determined and how adipogenesis is regulated by signalling and systemic factors. We have also gained appreciation that the adipogenic niche can influence tissue adipogenic capability. Approaches aimed at increasing adipogenesis over adipocyte hypertrophy can now be explored as a means to treat metabolic diseases.

Matrix regeneration proteins in the hypoxia-triggered exosomes of shoulder tenocytes and adipose-derived mesenchymal stem cells

Regenerative functions of exosomes rely on their contents which are influenced by pathological stimuli, including hypoxia, in rotator cuff tendon injuries (RCTI). The hypoxic environment triggers tenocytes and adjacent adipose-derived mesenchymal stem cells (ADMSCs) to release regenerative mediators to the ECM via the exosomes which elicit autocrine/paracrine responses to protect the tendon matrix from injury. We investigated the exosomal protein contents from tenocytes and subcutaneous ADMSCs from the shoulder of Yucatan microswine cultured under hypoxic conditions (2% O₂). The exosomal proteins were detected using high-resolution mass spectrometry nano-LC-MS/MS Tribrid system and were compiled using 'Scaffold' software. Hypoxic exosomes from tenocytes and ADMSCs carried 199 and 65 proteins, respectively. The key proteins identified by mass spectrometry and associated with ECM homeostasis from hypoxic ADMSCs included MMP2, COL6A, CTSD and TN-C and those from hypoxic tenocytes were THSB1, NSEP1, ITIH4 and TN-C. These findings were confirmed at the mRNA and protein level in the hypoxic ADMSCs and tenocytes. These proteins are involved in multiple signaling pathways of ECM repair/regeneration. This warrants further investigations for their translational significance in the management of RCTI.

Evaluation of the association between exosomal levels and female reproductive system and fertility outcome during aging: a systematic review protocol

BACKGROUND

Exosomes may have critical roles in the maternal-embryo cross-talk for the recognition and maintenance of pregnancy during maternal aging. Exosomes have the capability to carry developmental signaling molecules with the ability to modulate gene expressions and affect growth and regulation of embryo during pregnancy. Systematic review aims to evaluate age-related alterations in the exosomal content and functions that can influence the reproductive performance in human and animal models as conveyors of senescence signals.

METHODS

A literature search of electronic databases including MEDLINE (PubMed), Embase, ProQuest, Scopus, Google Scholar, WHO, SID, MAGIRAN, and Barakat will be conducted. Following the online search, articles will be screened by two independent reviewers according to inclusion and exclusion criteria. Eligible studies will be critically appraised by reviewers at the study level for methodological quality using Joanna Briggs Institute's standardized critical appraisal tools. The extracted data from selected studies will cover the study populations, methods, current evidence about the physiological role of extracellular vesicles and exosomes in reproductive system, relevant outcomes, and possible conclusions about the effectiveness of exposure.

DISCUSSION

Regarding the role of exosomes and their cargoes in the function of reproductive tract, the possible beneficial or adverse effects following exosomal administration from younger women to older women will be evaluated in the systematic review. As a result, exosome therapy could be suggested as a novel therapeutic agent if the favorable results are identified.

Tangential flow microfluidics for the capture and release of nanoparticles and extracellular vesicles on conventional and ultrathin membranes

Membranes have been used extensively for the purification and separation of biological species. A persistent challenge is the purification of species from concentrated feed solutions such as extracellular vesicles (EVs) from biological fluids. We investigated a new method to isolate micro- and nano-scale species termed tangential flow for analyte capture (TFAC), which is an extension of traditional tangential flow filtration (TFF). Initially, EV purification from plasma on ultrathin nanomembranes was compared between both normal flow filtration (NFF) and TFAC. NFF resulted in rapid formation of a protein cake which completely obscured any captured EVs and also prevented further transport across the membrane. On the other hand, TFAC showed capture of CD63 positive small EVs (sEVs) with minimal contamination. We explored the use of TFAC to capture target species over membrane pores, wash and then release in a physical process that does not rely upon affinity or chemical interactions. This process of TFAC was studied with model particles on both ultrathin nanomembranes and conventional thickness membranes (polycarbonate track-etch). Successful capture and release of model particles was observed using both membranes. Ultrathin nanomembranes showed higher efficiency of capture and release with significantly lower pressures indicating that ultrathin nanomembranes are well-suited for TFAC of delicate nanoscale particles such as EVs.

Nanotechnology and Immunotherapy in Ovarian Cancer: Tracing New Landscapes

Ovarian cancer (OC) is the seventh most common cancer in women worldwide. Standard therapeutic treatments involve debulking surgery combined with platinum-based chemotherapies. Of the patients with advanced-stage cancer who initially respond to current treatments, 50%-75% relapse. Immunotherapy-based approaches aimed at boosting antitumor immunity have recently emerged as promising tools to challenge tumor progression. Treatments with inhibitors of immune checkpoint molecules have shown impressive results in other types of tumors. However, only 15% of checkpoint inhibitors evaluated have proven successful in OC due to the immunosuppressive environment of the tumor and the transport barriers. This limits the efficacy of the existing immunotherapies. Nanotechnology-based delivery systems hold the potential to overcome such limitations. Various nanoformulations including polymeric, liposomes, and lipid-polymer hybrid nanoparticles have already been proposed to improve the biodistribution and targeting capabilities of drugs against tumor-associated immune cells, including dendritic cells and macrophages. In this review, we examine the impact of immunotherapeutic approaches that are currently under consideration for the treatment of OC. In this review, we also provide a comprehensive analysis of the existing nanoparticle-based synthetic strategies and their limitations and advantages over standard treatments. Furthermore, we discuss how the strength of the combination of nanotechnology with immunotherapy may help to overcome the current therapeutic limitations associated with their individual application and unravel a new paradigm in the treatment of this malignancy.

Exosomes derived from induced vascular progenitor cells promote angiogenesis in vitro and in an in vivo rat hindlimb ischemia model

Induced vascular progenitor cells (iVPCs) were created as an ideal cell type for regenerative medicine and have been reported to positively promote collateral blood flow and improve cardiac function in a rat model of myocardial ischemia. Exosomes have emerged as a novel biomedicine that mimics the function of the donor cells. We investigated the angiogenic activity of exosomes from iPVCs (iVPC-Exo) as a cell-free therapeutic approach for ischemia. Exosomes from iVPCs and rat aortic endothelial cells (RAECs) were isolated using a combination of ultrafiltration and size-exclusion chromatography. Nanoparticle tracking analysis revealed that exosome isolates fell within the exosomal diameter (<150 nm). These exosomes contained known markers Alix and TSG101, and their morphology was validated using transmission electron microscopy. When compared with RAECs, iVPCs significantly increased the secretion of exosomes. Cardiac microvascular endothelial cells and aortic ring explants were pretreated with RAEC-Exo or iVPC-Exo, and basal medium was used as a control. iVPC-Exo exerted an in vitro angiogenic effect on the proliferation, tube formation, and migration of endothelial cells and stimulated microvessel sprouting in an ex vivo aortic ring assay. Additionally, iVPC-Exo increased blood perfusion in a hindlimb ischemia model. Proangiogenic proteins (pentraxin-3 and insulin-like growth factor-binding protein-3) and microRNAs (-143-3p, -291b, and -20b-5p) were found to be enriched in iVPC-Exo, which may mediate iVPC-Exo induced vascular growth. Our findings demonstrate that treatment with iVPC-Exo promotes angiogenesis in vitro, ex vivo, and in vivo. Collectively, these findings indicate a novel cell-free approach for therapeutic angiogenesis.NEW & NOTEWORTHY The results of this work demonstrate exosomes as a novel physiological mechanism by which induced vascular progenitor cells exert their angiogenic effect. Moreover, angiogenic cargo of proteins and microRNAs may define the biological contributors in activating endothelial cells to form a new capillary plexus for ischemic vascular diseases.

The Role of Exosomes in Bone Remodeling: Implications for Bone Physiology and Disease

Bone remodeling represents a physiological phenomenon of continuous bone tissue renewal that requires fine orchestration of multiple cell types, which is critical for the understanding of bone disease but not yet clarified in precise detail. Exosomes, which are cell-secreted nanovesicles drawing increasing attention for their broad biosignaling functions, can shed new light on how multiple heterogeneous cells communicate for the purpose of bone remodeling. In the healthy bone, exosomes transmit signals favoring both bone synthesis and resorption, regulating the differentiation, recruitment, and activity of most cell types involved in bone remodeling and even assuming an active role in extracellular matrix mineralization. Additionally, in the ailing bone, they actively participate in pathogenic processes constituting also potential therapeutic agents and drug vectors. The present review summarizes the current knowledge on bone exosomes and bone remodeling in health and disease.

An Update on Novel Therapeutic Warfronts of Extracellular Vesicles (EVs) in Cancer Treatment: Where We Are Standing Right Now and Where to Go in the Future

Extracellular vesicles (EVs) are a heterogeneous group of membrane-bounded vesicles that are believed to be produced and secreted by presumably all cell types under physiological and pathological conditions, including tumors. EVs are very important vehicles in intercellular communications for both shorter and longer distances and are able to deliver a wide range of cargos including proteins, lipids, and various species of nucleic acids effectively. EVs have been emerging as a novel biotherapeutic platform to efficiently deliver therapeutic cargos to treat a broad range of diseases including cancer. This vast potential of drug delivery lies in their abilities to carry a variety of cargos and their ease in crossing the biological membranes. Similarly, their presence in a variety of body fluids makes them a potential biomarker for early diagnosis, prognostication, and surveillance of cancer. Here, we discuss the relatively least and understudied aspects of EV biology and tried to highlight the obstacles and limitations in their clinical applications and also described most of the new warfronts to beat cancer at multiple stages. However, much more challenges still remain to evaluate EV-based therapeutics, and we are very much hopeful that the current work prompts further discovery.

An Exosomal Urinary miRNA Signature for Early Diagnosis of Renal Fibrosis in Lupus Nephritis

For lupus nephritis (LN) management, it is very important to detect fibrosis at an early stage. Urinary exosomal miRNAs profiling can be used as a potential multi-marker phenotyping tool to identify early fibrosis. We isolated and characterised urinary exosomes and cellular pellets from patients with biopsy-proven LN (n = 45) and healthy controls (n = 20). LN chronicity index (CI) correlated with urinary exosomal miR-21, miR-150, and miR-29c (r = 0.565, 0.840, −0.559, respectively). This miRNA profile distinguished low CI from moderate-high CI in LN patients with a high sensitivity and specificity (94.4% and 99.8%). Furthermore, this multimarker panel predicted an increased risk of progression to end-stage renal disease (ESRD). Pathway analysis identified VEGFA and SP1 as common target genes for the three miRNAs. Immunohistochemistry in LN renal biopsies revealed a significant increase of COL1A1 and COL4A1 correlated with renal chronicity. SP1 decreased significantly in the high-CI group (p = 0.002). VEGFA levels showed no differences. In vitro experiments suggest that these miRNA combinations promote renal fibrosis by increasing profibrotic molecules through SP1 and Smad3/TGFβ pathways. In conclusion, a urinary exosomal multimarker panel composed of miR-21, miR-150, and miR-29c provides a non-invasive method to detect early renal fibrosis and predict disease progression in LN.

A cell-based assay for CD63-containing extracellular vesicles

Extracellular vesicles (EVs) are thought to be important in cell-cell communication and have elicited extraordinary interest as potential biomarkers of disease. However, quantitative methods to enable elucidation of mechanisms underlying release are few. Here, we describe a cell-based assay for monitoring EV release using the EV-enriched tetraspanin CD63 fused to the small, ATP-independent reporter enzyme, Nanoluciferase. Release of CD63-containing EVs from stably expressing cell lines was monitored by comparing luciferase activity in culture media to that remaining in cells. HEK293, U2OS, U87 and SKMel28 cells released 0.3%-0.6% of total cellular CD63 in the form of EVs over 5 hrs, varying by cell line. To identify cellular machinery important for secretion of CD63-containing EVs, we performed a screen of biologically active chemicals in HEK293 cells. While a majority of compounds did not significantly affect EV release, treating cells with the plecomacrolides bafilomycin or concanamycin, known to inhibit the V-ATPase, dramatically increased EV release. Interestingly, alkalization of the endosomal lumen using weak bases had no effect, suggesting a pH-independent enhancement of EV release by V-ATPase inhibitors. The ability to quantify EVs in small samples will enable future detailed studies of release kinetics as well as further chemical and genetic screening to define pathways involved in EV secretion.

The purification and identification of human blood serum proteins with affinity to the antitumor active RL2 lactaptin using magnetic microparticles

The cytopoxic effect of RL2 lactaptin (the recombinant analog of proteolytic fragment of human kappa-casein) toward tumor cells in vitro and in vivo presents it as a novel promising antitumor drug. The binding of any drug with serum proteins can affect their activity, distribution, rate of excretion and toxicity in the human body. Here, we studied the ability of RL2 to bind to various blood serum proteins. Using magnetic microparticles bearing by RL2 as an affinity matrix, in combination with mass spectrometry and western blot analysis, we found a number of blood serum proteins possessing affinity for RL2. Among them IgA, IgM and IgG subclasses of immunoglobulins, apolipoprotein A1 and various cortactin isoforms were identified. This data suggests that in the bloodstream RL2 lactaptin takes part in complicate protein-protein interactions, which can affect its activity.

An ultrasensitive electrochemical aptasensor for the determination of tumor exosomes based on click chemistry

Exosomes, lipid bilayer membrane vesicles, can guide various pathological and physiological processes. However, reliable, convenient and sensitive methods for exosome determination for early cancer diagnosis are still technically challenging. Herein, an electrochemical aptasensor based on click chemistry and the DNA hybridization chain reaction (HCR) for signal amplification has been developed for the ultrasensitive detection of tumor exosomes. CD63 aptamer was first immobilized on a glassy carbon electrode for capturing exosomes, and 4-oxo-2-nonenal alkyne (alkynyl-4-ONE) molecules, functionalized lipid electrophiles, were conjugated to the exosomes via the reaction of amino and aldehyde groups. Azide-labeled DNA probe as an anchor was then connected to the exosomes by copper (I)-catalyzed click chemistry. Signal amplification was achieved by HCR, and the numerous linked horseradish peroxidase (HRP) molecules could catalyze the reaction of o-phenylenediamine (OPD) and H₂O₂. The concentration of exosomes could be quantified by monitoring the electrochemical reduction current of 2,3-diaminophenazine (DAP). Under the optimal conditions, this method allowed the sensitive detection of exosomes in the range of 1.12 × 10² to 1.12 × 10⁸ particles/μL with a limit of detection (LOD) of 96 particles/μL. Furthermore, the present assay enabled sensitive and accurate quantification of exosomes in human serum, and it has high potential for exosome analysis in clinical samples.

Exosomes: Diagnostic Biomarkers and Therapeutic Delivery Vehicles for Cancer

Exosomes are described as nanoscale extracellular vesicles (EVs) secreted by multiple cell types and extensively distributed in various biological fluids. They contain multifarious bioactive molecules and transfer them to adjoining or distal cells through systemic circulation, participating in intracellular and intercellular communication, and modulating host-tumor cell interactions. Recent research has indicated that exosomes obtained from different biological fluids and their contents (proteins, nucleic acids, glycoconjugates, and lipids) can serve as biomarkers for cancer diagnosis, prognosis, and therapeutic response. Furthermore, the discovery of exosomes as therapeutic delivery vehicles has drawn much attention in antineoplastic drug delivery. They can be utilized for therapeutic delivery of proteins, genetic drugs, and chemotherapeutic drugs. Herein, this review summarizes the biogenesis, structure, and components of exosomes, focusing primarily on their two possible applications as diagnostic biomarkers and therapeutic delivery vehicles for cancers.

The Secret Life of Exosomes: What Bees Can Teach Us About Next-Generation Therapeutics

Mechanistic exploration has pinpointed nanosized extracellular vesicles, known as exosomes, as key mediators of the benefits of cell therapy. Exosomes appear to recapitulate the benefits of cells and more. As durable azoic entities, exosomes have numerous practical and conceptual advantages over cells. Will cells end up just being used to manufacture exosomes, or will they find lasting value as primary therapeutic agents? Here, a venerable natural process-the generation of honey-serves as an instructive parable. Flowers make nectar, which bees collect and process into honey. Cells make conditioned medium, which laboratory workers collect and process into exosomes. Unlike flowers, honey is durable, compact, and nutritious, but these facts do not negate the value of flowers themselves. The parallels suggest new ways of thinking about next-generation therapeutics.

Coated cationic lipid-nanoparticles entrapping miR-660 inhibit tumor growth in patient-derived xenografts lung cancer models

Lung cancer is the leading cause of cancer-related deaths. Late diagnosis and inadequate therapies contribute to poor outcomes. MicroRNAs (miRNAs) are small non-coding RNAs and are involved in lung cancer development. Because miRNAs simultaneously regulate several cancer-related genes, they represent an interesting therapeutic approach for cancer treatment. We have developed Coated Cationic Lipid-nanoparticles entrapping miR-660 (CCL660) and intraperitoneally administered (1.5 mg/Kg) twice a week for four weeks into SCID mice carrying subcutaneously lung cancer Patients Derived Xenografts (PDXs). Obtained data demonstrated that miR-660 is down-regulated in lung cancer patients and that its replacement inhibited lung cancer growth by inhibiting the MDM2-P53 axis. Furthermore, systemic delivery of CCL660 increased miRNA levels in tumors and significantly reduced tumor growth in two different P53 wild-type PDXs without off-target effects. MiR-660 administration reduced cancer cells proliferation by inhibiting MDM2 and restoring P53 function and its downstream effectors such as p21. Interestingly, anti-tumoral effects of CCL660 also in P53 mutant PDXs but with a functional p21 pathway were observed. Stable miR-660 expression inhibited the capacity of H460 metastatic lung cancer cells to form lung nodules when injected intravenously into SCID mice suggesting a potential role of miR-660 in metastatic dissemination. To investigate the potential toxic effects of both miRNAs and delivery agents, an in vitro approach revealed that miR-660 replacement did not induce any changes in both mouse and human normal cells. Interestingly, lipid-nanoparticle delivery of synthetic miR-660 had no immunological off-target or acute/chronic toxic effects on immunocompetent mice. Altogether, our results highlight the potential role of coated cationic lipid-nanoparticles entrapping miR-660 in lung cancer treatment without inducing immune-related toxic effects.

Effect of exosomes from adipose-derived stem cells on the apoptosis of Schwann cells in peripheral nerve injury

Aims

Recovery after peripheral nerve injury (PNI) is often difficult, and there is no optimal treatment. Schwann cells (SCs) are important for peripheral nerve regeneration, so SC‐targeting treatments have gained importance. Adipose‐derived stem cells (ADSCs) and their exosomes can promote peripheral nerve repair, but their interactions with SCs are unclear.

Methods

Purified SCs from sciatic nerve injury sites were harvested, and apoptosis and proliferation of SCs at post‐PNI 24 hours were analyzed. The effects of coculture with ADSCs and different concentrations of ADSC‐derived exosomes (ADSC‐Exo) were studied through in vitro experiments by flow cytometry, CCK8 assay, immunofluorescence staining, and histological analysis. The expression of the apoptosis‐related genes Bcl‐2 and Bax was also analyzed by qRT‐PCR.

Results

ADSC‐Exo reduced the apoptosis of SCs after PNI by upregulating the anti‐apoptotic Bcl‐2 mRNA expression and downregulating the pro‐apoptotic Bax mRNA expression. Further, it also improved the proliferation rate of SCs. This effect was confirmed by the morphological and histological findings in PNI model rats.

Conclusion

Our results present a novel exosome‐mediated mechanism for ADSC‐SC cross talk that reduces the apoptosis and promotes the proliferation of SCs and may have therapeutic potential in the future.

Local pharmacological induction of angiogenesis: Drugs for cells and cells as drugs

The past decades have seen significant advances in pro-angiogenic strategies based on delivery of molecules and cells for conditions such as coronary artery disease, critical limb ischemia and stroke. Currently, three major strategies are evolving. Firstly, various pharmacological agents (growth factors, interleukins, small molecules, DNA/RNA) are locally applied at the ischemic region. Secondly, preparations of living cells with considerable bandwidth of tissue origin, differentiation state and preconditioning are delivered locally, rarely systemically. Thirdly, based on the notion, that cellular effects can be attributed mostly to factors secreted in situ, the cellular secretome (conditioned media, exosomes) has come into the spotlight. We review these three strategies to achieve (neo)angiogenesis in ischemic tissue with focus on the angiogenic mechanisms they tackle, such as transcription cascades, specific signalling steps and cellular gases. We also include cancer-therapy relevant lymphangiogenesis, and shall seek to explain why there are often conflicting data between in vitro and in vivo. The lion's share of data encompassing all three approaches comes from experimental animal work and we shall highlight common technical obstacles in the delivery of therapeutic molecules, cells, and secretome. This plethora of preclinical data contrasts with a dearth of clinical studies. A lack of adequate delivery vehicles and standardised assessment of clinical outcomes might play a role here, as well as regulatory, IP, and manufacturing constraints of candidate compounds; in addition, completed clinical trials have yet to reveal a successful and efficacious strategy. As the biology of angiogenesis is understood well enough for clinical purposes, it will be a matter of time to achieve success for well-stratified patients, and most probably with a combination of compounds.

Articular fibrocartilage - Why does hyaline cartilage fail to repair?

Once damaged, articular cartilage has a limited potential to repair. Clinically, a repair tissue is formed, yet, it is often mechanically inferior fibrocartilage. The use of monolayer expanded versus naïve cells may explain one of the biggest discrepancies in mesenchymal stromal/stem cell (MSC) based cartilage regeneration. Namely, studies utilizing monolayer expanded MSCs, as indicated by numerous in vitro studies, report as a main limitation the induction of type X collagen and hypertrophy, a phenotype associated with endochondral bone formation. However, marrow stimulation and transfer studies report a mechanically inferior collagen I/II fibrocartilage as the main outcome. Therefore, this review will highlight the collagen species produced during the different therapeutic approaches. New developments in scaffold design and delivery of therapeutic molecules will be described. Potential future directions towards clinical translation will be discussed. New delivery mechanisms are being developed and they offer new hope in targeted therapeutic delivery.

The Contribution of the 20S Proteasome to Proteostasis

The last decade has seen accumulating evidence of various proteins being degraded by the core 20S proteasome, without its regulatory particle(s). Here, we will describe recent advances in our knowledge of the functional aspects of the 20S proteasome, exploring several different systems and processes. These include neuronal communication, post-translational processing, oxidative stress, intrinsically disordered protein regulation, and extracellular proteasomes. Taken together, these findings suggest that the 20S proteasome, like the well-studied 26S proteasome, is involved in multiple biological processes. Clarifying our understanding of its workings calls for a transformation in our perception of 20S proteasome-mediated degradation—no longer as a passive and marginal path, but rather as an independent, coordinated biological process. Nevertheless, in spite of impressive progress made thus far, the field still lags far behind the front lines of 26S proteasome research. Therefore, we also touch on the gaps in our knowledge of the 20S proteasome that remain to be bridged in the future.

Scutellarin-treated exosomes increase claudin 5, occludin and ZO1 expression in rat brain microvascular endothelial cells

Homocysteine has been reported to be an independent risk factor for stroke. Scutellarin (Scu) dilates cerebral blood vessels and promotes anti-platelet aggregation; however, the mechanism by which Scu and Scu-treated exosomes protect against cerebrovascular disease is unclear. The aim of the present study was to investigate the mechanisms underlying the effects of Scu and Scu-treated exosomes on tight junction proteins in the blood-brain barrier. Rat brain microvascular endothelial cells (RBMVECs) were cultured and divided into five groups: Control, model, Scu, exosomes derived from RBMVECs and exosomes derived from RBMVECs after Scu administration. MTT, lactate dehydrogenase (LDH) and nitric oxide (NO) assays were performed to assess cell viability and injury. Reactive oxygen species (ROS) levels were detected using spectrophotometry and immunofluorescence. Western blotting and immunofluorescence were performed to measure cluster of differentiation (CD) 63, claudin 5, occludin and tight junction protein 1 (ZO1) expression. The results revealed that treatment with Scu and Scu-treated exosomes enhanced cell viability, reduced cell injury, increased NO levels, upregulated CD63, claudin 5, occludin and ZO1, and decreased LDH and ROS levels. These data suggest that Scu and Scu-treated exosomes protect homocysteine-induced RBMVECs via increased claudin 5, occludin and ZO1 expression.

The State of Exosomes Research: A Global Visualized Analysis

Objective

With the development of exosomes studies increased around the whole world. Our present study was aimed to investigate the global status and trends in exosomes field.

Methods

Publications related to exosomes studies from 1994 to 2017 were retrieved from the Web of Science database. The data source was studied and indexed by using bibliometric methodology. For visualized study, VOS viewer software was used to conduct bibliographic coupling analysis, coauthorship analysis, cocitation analysis, and cooccurrence analysis and to analyze the publication trend in exosomes research.

Results

A total of 4960 publications were included. The relative research interests and number of publications were increasing per year globally. The USA made the highest contributions to the global research with the most citations, the highest H-index, and the most total link strength, while Sweden had the highest average citation per item. The journal PLOS ONE had the highest publication number. The Natl Canc Ctr was the most contributive institutions. Studies could be divided into three clusters: mechanism study, in vivo study, and in vitro study.

Conclusions

The efforts should be put into mechanism studies, predicted to be the next hot spots in exosomes studies.

Proteomic and Post-Translational Modification Profiling of Exosome-Mimetic Nanovesicles Compared to Exosomes

Issues associated with upscaling exosome production for therapeutic use may be overcome through utilizing artificial exosomes. Cell-derived mimetic nanovesicles (M-NVs) are a potentially promising alternative to exosomes for clinical applicability, demonstrating higher yield without incumbent production and isolation issues. Although several studies have shown that M-NVs have similar morphology, size and therapeutic potential compared to exosomes, comprehensive characterization and to what extent M-NVs components mimic exosomes remain elusive. M-NVs were generated through the extrusion of cells and proteomic profiling demonstrated an enrichment of proteins associated with membrane and cytosolic components. The proteomic data herein reveal a subset of proteins that are highly abundant in M-NVs in comparison to exosomes. M-NVs contain proteins that largely represent the parental cell proteome, whereas the profile of exosomal proteins highlight their endosomally derived origin. This advantage of M-NVs alleviates the necessity of endosomal sorting of endogenous therapeutic proteins or RNA into exosomes. This study also highlights differences in protein post-translational modifications among M-NVs, as distinct from exosomes. Overall this study provides key insights into defining the proteome composition of M-NVs as a distinct from exosomes, and the potential advantage of M-NVs as an alternative nanocarrier when spontaneous endosomal sorting of therapeutics are limited.

Exosome microRNA signatures in patients with complex regional pain syndrome undergoing plasma exchange

Background

Therapeutic plasma exchange (PE) or plasmapheresis is an extracorporeal procedure employed to treat immunological disorders. Exosomes, nanosized vesicles of endosomal origin, mediate intercellular communication by transferring cargo proteins and nucleic acids and regulate many pathophysiological processes. Exosomal miRNAs are potential biomarkers due to their stability and dysregulation in diseases including complex regional pain syndrome (CRPS), a chronic pain disorder with persistent inflammation. A previous study showed that a subset of CRPS patients responded to PE.

Methods

As a proof-of-concept, we investigated the PE-induced exosomal miRNA changes in six CRPS patients. Plasma cytokine levels were measured by HPLC and correlated with miRNA expression. Luciferase assay following co-transfection of HEK293 cells with target 3′UTR constructs and miRNA mimics was used to evaluate miRNA mediated gene regulation of target mRNA. Transient transfection of THP-1 cells with miRNA mimics followed by estimation of target gene and protein expression was used to validate the findings.

Results

Comparison of miRNAs in exosomes from the serum of three responders and three poor-responders showed that 17 miRNAs differed significantly before and after therapy. Of these, poor responders had lower exosomal hsa-miR-338-5p. We show that miR-338-5p can bind to the interleukin 6 (IL-6) 3′ untranslated region and can regulate IL-6 mRNA and protein levels in vitro. PE resulted in a significant reduction of IL-6 in CRPS patients.

Conclusions

We propose that lower pretreatment levels of miR-338-5p in poor responders are linked to IL-6 levels and inflammation in CRPS. Our data suggests the feasibility of exploring exosomal miRNAs as a strategy in patient stratification for maximizing therapeutic outcome of PE.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1833-3) contains supplementary material, which is available to authorized users.

Vehicles of intercellular communication: exosomes and HIV-1

The terms extracellular vesicles, microvesicles, oncosomes, or exosomes are often used interchangeably as descriptors of particles that are released from cells and comprise a lipid membrane that encapsulates nucleic acids and proteins. Although these entities are defined based on a specific size range and/or mechanism of release, the terminology is often ambiguous. Nevertheless, these vesicles are increasingly recognized as important modulators of intercellular communication. The generic characterization of extracellular vesicles could also be used as a descriptor of enveloped viruses, highlighting the fact that extracellular vesicles and enveloped viruses are similar in both composition and function. Their high degree of similarity makes differentiating between vesicles and enveloped viruses in biological specimens particularly difficult. Because viral particles and extracellular vesicles are produced simultaneously in infected cells, it is necessary to separate these populations to understand their independent functions. We summarize current understanding of the similarities and differences of extracellular vesicles, which henceforth we will refer to as exosomes, and the enveloped retrovirus, HIV-1. Here, we focus on the presence of these particles in semen, as these are of particular importance during HIV-1 sexual transmission. While there is overlap in the terminology and physical qualities between HIV-1 virions and exosomes, these two types of intercellular vehicles may differ depending on the bio-fluid source. Recent data have demonstrated that exosomes from human semen serve as regulators of HIV-1 infection that may contribute to the remarkably low risk of infection per sexual exposure.

Exosomes from endothelial progenitor cells improve outcomes of the lipopolysaccharide-induced acute lung injury

Background

The acute respiratory distress syndrome (ARDS) is characterized by disruption of the alveolar-capillary barrier resulting in accumulation of proteinaceous edema and increased inflammatory cells in the alveolar space. We previously found that endothelial progenitor cell (EPC) exosomes prevent endothelial dysfunction and lung injury in sepsis in part due to their encapsulation of miRNA-126. However, the effects of EPC exosomes in acute lung injury (ALI) remain unknown.

Methods

To determine if EPC exosomes would have beneficial effects in ALI, intratracheal administration of lipopolysaccharide (LPS) was used to induce ALI in mice. Lung permeability, inflammation, and the role of miRNA-126 in the alveolar-epithelial barrier function were examined.

Results

The intratracheal administration of EPC exosomes reduced lung injury following LPS-induced ALI at 24 and 48 h. Compared to placebo, intratracheal administration of EPC exosomes significantly reduced the cell number, protein concentration, and cytokines/chemokines in the bronchoalveolar lavage fluid (BALF), indicating a reduction in permeability and inflammation. Further, EPC exosomes reduced myeloperoxidase (MPO) activity, lung injury score, and pulmonary edema, demonstrating protection against lung injury. Murine fibroblast (NIH3T3) exosomes, which do not contain abundant miRNA-126, did not provide these beneficial effects. In human small airway epithelial cells (SAECs), we found that overexpression of miRNA-126-3p can target phosphoinositide-3-kinase regulatory subunit 2 (PIK3R2), while overexpression of miRNA-126-5p inhibits the inflammatory alarmin HMGB1 and permeability factor VEGFα. Interestingly, both miR-126-3p and 5p increase the expression of tight junction proteins suggesting a potential mechanism by which miRNA-126 may mitigate LPS-induced lung injury.

Conclusions

Our data demonstrated that human EPC exosomes are beneficial in LPS-induced ALI mice, in part through the delivery of miRNA-126 into the injured alveolus.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2339-3) contains supplementary material, which is available to authorized users.

Exosome Release Is Regulated by mTORC1

Exosomes are small membrane-bound vesicles released into extracellular spaces by many types of cells. These nanovesicles carry proteins, mRNA, and miRNA, and are involved in cell waste management and intercellular communication. In the present study, it is shown that exosome release, which leads to net loss of cellular membrane and protein content, is negatively regulated by mechanistic target of rapamycin complex 1 (mTORC1). It is found that in cells and animal models exosome release is inhibited by sustained activation of mTORC1, leading to intracellular accumulation of CD63-positive exosome precursors. Inhibition of mTORC1 by rapamycin or nutrient and growth factor deprivation stimulates exosome release, which occurs concomitantly with autophagy. The drug-stimulated release is blocked by siRNA-mediated downregulation of small GTPase Rab27A. Analysis of the cargo content in exosomes released from rapamycin-treated cells reveals that inhibition of mTORC1 does not significantly alter its majority protein and miRNA profiles. These observations demonstrate that exosome release, like autophagy, is negatively regulated by mTORC1 in response to changes in nutrient and growth factor conditions.

Addressing the Manufacturing Challenges of Cell-Based Therapies

Exciting developments in the cell therapy field over the last decades have led to an increasing number of clinical trials and the first cell products receiving marketing authorization. In spite of substantial progress in the field, manufacturing of cell-based therapies presents multiple challenges that need to be addressed in order to assure the development of safe, efficacious, and cost-effective cell therapies.The manufacturing process of cell-based therapies generally requires tissue collection, cell isolation, culture and expansion (upstream processing), cell harvest, separation and purification (downstream processing), and, finally, product formulation and storage. Each one of these stages presents significant challenges that have been the focus of study over the years, leading to innovative and groundbreaking technological advances, as discussed throughout this chapter.Delivery of cell-based therapies relies on defining product targets while controlling process variable impact on cellular features. Moreover, commercial viability is a critical issue that has had damaging consequences for some therapies. Implementation of cost-effectiveness measures facilitates healthy process development, potentially being able to influence end product pricing.Although cell-based therapies represent a new level in bioprocessing complexity in every manufacturing stage, they also show unprecedented levels of therapeutic potential, already radically changing the landscape of medical care.

Bone-Derived Extracellular Vesicles: Novel Players of Interorgan Crosstalk

An increasing number of studies have shown that bone plays an active role in regulating glucose metabolism, affects renal, and cardiovascular diseases and even influences the development of offspring. These novel findings have indicated that bone plays a much more important role in the human body than only providing physical support. However, further investigations of the mechanisms underlying the effects of bone are needed. Recently, extracellular vesicles (EVs) have received increased attention because they can transfer functional proteins, mRNAs, and miRNAs between cells/organs. After reviewing the existing evidence, we hypothesized that bone may be involved in interorgan communication via EVs. Further research exploring bone-derived EVs may facilitate the understanding of bone as a multifunctional organ.

Stem Cell Extracellular Vesicles in Skin Repair

Stem cell extracellular vesicles (EVs) have been widely studied because of their excellent therapeutic potential. EVs from different types of stem cell can improve vascularization as well as aid in the treatment of cancer and neurodegenerative diseases. The skin is a complex organ that is susceptible to various types of injury. Strategies designed to restore epithelial tissues’ integrity with stem cell EVs have shown promising results. Different populations of stem cell EVs are able to control inflammation, accelerate skin cell migration and proliferation, control wound scarring, improve angiogenesis, and even ameliorate signs of skin aging. However, large-scale production of such stem cell EVs for human therapy is still a challenge. This review focuses on recent studies that explore the potential of stem cell EVs in skin wound healing and skin rejuvenation, as well as challenges of their use in therapy.

Tangential Flow Filtration for Highly Efficient Concentration of Extracellular Vesicles from Large Volumes of Fluid

Concentration of extracellular vesicles (EVs) from biological fluids in a scalable and reproducible manner represents a major challenge. This study reports the use of tangential flow filtration (TFF) for the highly efficient isolation of EVs from large volumes of samples. When compared to ultracentrifugation (UC), which is the most widely used method to concentrate EVs, TFF is a more efficient, scalable, and gentler method. Comparative assessment of TFF and UC of conditioned cell culture media revealed that the former concentrates EVs of comparable physicochemical characteristics, but with higher yield, less single macromolecules and aggregates (<15 nm in size), and improved batch-to-batch consistency in half the processing time (1 h). The TFF protocol was then successfully implemented on fluids derived from patient lipoaspirate. EVs from adipose tissue are of high clinical relevance, as they are expected to mirror the regenerative properties of the parent cells.

Approaches to therapeutic angiogenesis for ischemic heart disease

Ischemic heart disease (IHD) is caused by the narrowing of arteries that work to provide blood, nutrients, and oxygen to the myocardial tissue. The worldwide epidemic of IHD urgently requires innovative treatments despite the significant advances in medical, interventional, and surgical therapies for this disease. Angiogenesis is a physiological and pathophysiological process that initiates vascular growth from pre-existing blood vessels in response to a lack of oxygen. This process occurs naturally over time and has encouraged researchers and clinicians to investigate the outcomes of accelerating or enhancing this angiogenic response as an alternative IHD therapy. Therapeutic angiogenesis has been shown to revascularize ischemic heart tissue, reduce the progression of tissue infarction, and evade the need for invasive surgical procedures or tissue/organ transplants. Several approaches, including the use of proteins, genes, stem/progenitor cells, and various combinations, have been employed to promote angiogenesis. While clinical trials for these approaches are ongoing, microvesicles and exosomes have recently been investigated as a cell-free approach to stimulate angiogenesis and may circumvent limitations of using viable cells. This review summarizes the approaches to accomplish therapeutic angiogenesis for IHD by highlighting the advances and challenges that addresses the applicability of a potential pro-angiogenic medicine.

Therapeutic Targeting Cancer-Initiating Cell Markers by Exosome miRNA: Efficacy and Functional Consequences Exemplified for claudin7 and EpCAM

AIM: Transfer of exosomes (Exo) miRNA was described interfering with tumor progression. We here explored for claudin7 (cld7) and EpCAM (EpC), cancer-initiating-cell markers in colorectal and pancreatic cancer, the efficacy of Exo loading with miRNA and miRNA transfer. METHODS: Exo were collected from nontransformed mouse (NIH3T3) and rat lung fibroblasts (rFb), which were transfected with Tspan8 cDNA (NIH3T3-Tspan8, rFb-Tspan8). Exo were loaded by electroporation with miRNA. The transfer of Exo-miRNA was evaluated in vitro and in vivo in a rat pancreatic (ASML) and a human colon (SW948) cancer line. RESULTS: NIH3T3-Tspan8- or rFb-Tspan8-Exo were efficiently loaded with cld7- or EpC-miRNA. Exo targeting in vivo was strongly improved by tailoring with Tspan8. Exo-miRNA transfer into tumor targets promoted cld7, respectively, EpC downregulation by 33%-60%. Cld7 silencing was accompanied by reduced expression of additional cancer-initiating cell markers and NOTCH. EpC silencing reduced vimentin, N-cadherin, and Nanog expression. The Exo-miRNA transfer affected anchorage-independent growth, motility, and invasion. CONCLUSIONS: Exo are efficiently loaded with miRNA, miRNA-delivery being supported by Exo tailoring. Partial cld7 and EpC silencing by Exo miRNA affects metastasis-promoting tumor cell activities. The findings suggest miRNA loading of tailored Exo as an easy approachable and efficient adjuvant therapy.

The Ambiguous Roles of Extracellular Vesicles in HIV Replication and Pathogenesis

Cells from all kingdoms of life can release membrane-enclosed vesicles to the extracellular milieu. These extracellular vesicles (EVs) may function as mediators of intercellular communication, allowing the transfer of biologically active molecules between cells and organisms. It has become clear that HIV particles and certain types of EVs, such as exosomes, share many similarities regarding morphology, composition, and biogenesis. This review presents a summary of the literature describing the intricate relationship between HIV and EVs biogenesis. Also, we discuss the latest progress toward understanding the mechanisms by which EVs influence HIV pathogenesis, as well as, how HIV modulates EVs composition in infected cells to facilitate viral spread.

An Endothelial-to-Adipocyte Extracellular Vesicle Axis Governed by Metabolic State

We have uncovered the existence of extracellular vesicle (EV)-mediated signaling between cell types within the adipose tissue (AT) proper. This phenomenon became evident in our attempts at generating an adipocyte-specific knockout of caveolin 1 (cav1) protein. Although we effectively ablated the CAV1 gene in adipocytes, cav1 protein remained abundant. With the use of newly generated mouse models, we show that neighboring endothelial cells (ECs) transfer cav1-containing EVs to adipocytes in vivo, which reciprocate by releasing EVs to ECs. AT-derived EVs contain proteins and lipids capable of modulating cellular signaling pathways. Furthermore, this mechanism facilitates transfer of plasma constituents from ECs to the adipocyte. The transfer event is physiologically regulated by fasting/refeeding and obesity, suggesting EVs participate in the tissue response to changes in the systemic nutrient state. This work offers new insights into the complex signaling mechanisms that exist among adipocytes, stromal vascular cells, and, potentially, distal organs.

Lipidomic profiling of extracellular vesicles derived from prostate and prostate cancer cell lines

BACKGROUND

Extracellular vesicles (EVs) are produced and secreted from most cells of the body and can be recovered in biological fluids. Although there has been extensive characterisation of the protein and nucleic acid component of EVs, their lipidome has received little attention and may represent a unique and untapped source of biomarkers for prostate cancer diagnosis and prognosis.

METHODS

EVs were isolated from non-tumourigenic (RWPE1), tumourigenic (NB26) and metastatic (PC-3) prostate cell lines. Lipids were extracted and subsequently used for targeted lipidomics analysis for the quantitation of molecular lipid species.

RESULTS

A total of 187 molecular lipid species were quantitatively identified in EV samples showing differential abundance between RWPE1, NB26 and PC-3 EV samples. Fatty acids, glycerolipids and prenol lipids were more highly abundant in EVs from non-tumourigenic cells, whereas sterol lipids, sphingolipids and glycerophospholipids were more highly abundant in EVs from tumourigenic or metastatic cells.

CONCLUSIONS

This study identified differences in the molecular lipid species of prostate cell-derived EVs, increasing our understanding of the changes that occur to the EV lipidome during prostate cancer progression. These differences highlight the importance of characterising the EV lipidome, which may lead to improved diagnostic and prognostic biomarkers for prostate cancer.

Targeting extracellular vesicles to injured tissue using membrane cloaking and surface display

BACKGROUND

Extracellular vesicles (EVs) and exosomes are nano-sized, membrane-bound vesicles shed by most eukaryotic cells studied to date. EVs play key signaling roles in cellular development, cancer metastasis, immune modulation and tissue regeneration. Attempts to modify exosomes to increase their targeting efficiency to specific tissue types are still in their infancy. Here we describe an EV membrane anchoring platform termed "cloaking" to directly embed tissue-specific antibodies or homing peptides on EV membrane surfaces ex vivo for enhanced vesicle uptake in cells of interest. The cloaking system consists of three components: DMPE phospholipid membrane anchor, polyethylene glycol spacer and a conjugated streptavidin platform molecule, to which any biotinylated molecule can be coupled for EV decoration.

RESULTS

We demonstrate the utility of membrane surface engineering and biodistribution tracking with this technology along with targeting EVs for enhanced uptake in cardiac fibroblasts, myoblasts and ischemic myocardium using combinations of fluorescent tags, tissue-targeting antibodies and homing peptide surface cloaks. We compare cloaking to a complementary approach, surface display, in which parental cells are engineered to secrete EVs with fusion surface targeting proteins.

CONCLUSIONS

EV targeting can be enhanced both by cloaking and by surface display; the former entails chemical modification of preformed EVs, while the latter requires genetic modification of the parent cells. Reduction to practice of the cloaking approach, using several different EV surface modifications to target distinct cells and tissues, supports the notion of cloaking as a platform technology.

Single-Vesicle Assays Using Liposomes and Cell-Derived Vesicles: From Modeling Complex Membrane Processes to Synthetic Biology and Biomedical Applications

The plasma membrane is of central importance for defining the closed volume of cells in contradistinction to the extracellular environment. The plasma membrane not only serves as a boundary, but it also mediates the exchange of physical and chemical information between the cell and its environment in order to maintain intra- and intercellular functions. Artificial lipid- and cell-derived membrane vesicles have been used as closed-volume containers, representing the simplest cell model systems to study transmembrane processes and intracellular biochemistry. Classical examples are studies of membrane translocation processes in plasma membrane vesicles and proteoliposomes mediated by transport proteins and ion channels. Liposomes and native membrane vesicles are widely used as model membranes for investigating the binding and bilayer insertion of proteins, the structure and function of membrane proteins, the intramembrane composition and distribution of lipids and proteins, and the intermembrane interactions during exo- and endocytosis. In addition, natural cell-released microvesicles have gained importance for early detection of diseases and for their use as nanoreactors and minimal protocells. Yet, in most studies, ensembles of vesicles have been employed. More recently, new micro- and nanotechnological tools as well as novel developments in both optical and electron microscopy have allowed the isolation and investigation of individual (sub)micrometer-sized vesicles. Such single-vesicle experiments have revealed large heterogeneities in the structure and function of membrane components of single vesicles, which were hidden in ensemble studies. These results have opened enormous possibilities for bioanalysis and biotechnological applications involving unprecedented miniaturization at the nanometer and attoliter range. This review will cover important developments toward single-vesicle analysis and the central discoveries made in this exciting field of research.

Endogenous exosome labelling with an amphiphilic NIR-fluorescent probe

The recognition of the biological, diagnostic and medical importance of exosomes has given rise to an urgent need for efficient labelling of these extracellular vesicles in ways that do not alter their inherent characteristics. We report for the first time an endogenous method to NIR-fluorescent labelled exosomes using an amphiphilic probe without the need for immunolabelling or synthetic or chromatographic manipulation of exosomes. Comparative analyses of labelled and unlabelled exosomes with NTA, AFM, flow cytometry and immunoblot analysis all show a high degree of similarity. Spectroscopic analysis and fluorescence imaging confirmed the ability to visualise purified NIR-exosomes.

A mechanistic roadmap for the clinical application of cardiac cell therapies

The development of cells for regenerative therapy has encountered many pitfalls on its path to clinical translation. In cardiology, clinical studies of heart-targeted cell therapies began two decades ago, yet progress towards reaching an approved product has been slow. In this Perspective, I provide an overview of recent cardiac cell therapies, with a focus on the hurdles limiting the translation of cell products from research laboratories to clinical practice. By focusing on heart failure as a target indication, I argue that strategies for overcoming limitations in clinical translation require an increasing emphasis on mechanism-supported efficacy, rather than on phenomenological observations. As research progresses from cells to paracrine mechanisms to defined factors, identifying those defined factors that are involved in achieving superior therapeutic efficacy will better inform the use of cells as therapeutic candidates. The next generation of cell-free biologics may provide the benefits of cell therapy without the intrinsic limitations of whole-cell products.

Stem Cell-Derived Exosome in Cardiovascular Diseases: Macro Roles of Micro Particles

The stem cell-based therapy has emerged as the promising therapeutic strategies for cardiovascular diseases (CVDs). Recently, increasing evidence suggest stem cell-derived active exosomes are important communicators among cells in the heart via delivering specific substances to the adjacent/distant target cells. These exosomes and their contents such as certain proteins, miRNAs and lncRNAs exhibit huge beneficial effects on preventing heart damage and promoting cardiac repair. More importantly, stem cell-derived exosomes are more effective and safer than stem cell transplantation. Therefore, administration of stem cell-derived exosomes will expectantly be an alternative stem cell-based therapy for the treatment of CVDs. Furthermore, modification of stem cell-derived exosomes or artificial synthesis of exosomes will be the new therapeutic tools for CVDs in the future. In addition, stem cell-derived exosomes also have been implicated in the diagnosis and prognosis of CVDs. In this review, we summarize the current advances of stem cell-derived exosome-based treatment and prognosis for CVDs, including their potential benefits, underlying mechanisms and limitations, which will provide novel insights of exosomes as a new tool in clinical therapeutic translation in the future.

A low voltage nanopipette dielectrophoretic device for rapid entrapment of nanoparticles and exosomes extracted from plasma of healthy donors

An insulator-based dielectrophoresis (iDEP) is a label-free method that has been extensively utilized for manipulation of nanoparticles, cells, and biomolecules. Here, we present a new iDEP approach that can rapidly trap nanoparticles at the close proximity of a glass nanopipette’s tip by applying 10 V/cm direct current (DC) across the pipette’s length. The trapping mechanism was systemically studied using both numerical modeling and experimental observations. The results showed that the particle trapping was determined to be controlled by three dominant electrokinetic forces including dielectrophoretic, electrophoretic and electroosmotic force. Furthermore, the effect of the ionic strength, the pipette’s geometry, and the applied electric field on the entrapment efficiency was investigated. To show the application of our device in biomedical sciences, we demonstrated the successful entrapment of fluorescently tagged liposomes and unlabeled plasma-driven exosomes from the PBS solution. Also, to illustrate the selective entrapment capability of our device, 100 nm liposomes were extracted from the PBS solution containing 500 nm polystyrene particles at the tip of the pipette as the voltage polarity was reversed.

Advances, challenges, and opportunities in extracellular RNA biology: insights from the NIH exRNA Strategic Workshop

Extracellular RNA (exRNA) has emerged as an important transducer of intercellular communication. Advancing exRNA research promises to revolutionize biology and transform clinical practice. Recent efforts have led to cutting-edge research and expanded knowledge of this new paradigm in cell-to-cell crosstalk; however, gaps in our understanding of EV heterogeneity and exRNA diversity pose significant challenges for continued development of exRNA diagnostics and therapeutics. To unravel this complexity, the NIH convened expert teams to discuss the current state of the science, define the significant bottlenecks, and brainstorm potential solutions across the entire exRNA research field. The NIH Strategic Workshop on Extracellular RNA Transport helped identify mechanistic and clinical research opportunities for exRNA biology and provided recommendations on high priority areas of research that will advance the exRNA field.

MicroRNA-6869-5p acts as a tumor suppressor via targeting TLR4/NF-κB signaling pathway in colorectal cancer

Many studies have implicated that microRNAs (miRNAs), as non-coding RNAs, play important roles in the development and progression of colorectal cancer (CRC). However, little is known about the role of a newly identified miRNA, miR-6869-5p, in CRC. We aim to investigate the modifying effects and underlying mechanisms of miR-6869-5 in colorectal carcinogenesis and progression. Significantly reduced levels of miR-6869-5p were observed in both serum exosomes tumor tissue samples from patients with CRC. The prediction of targets of miR-6869-5p in databases of targetscan, microRNA. ORG and miRDBA revealed that toll-like receptor 4 (TLR4) is a potential target for this miRNA. MiR-6869-5p could inhibit cell proliferation and the production of inflammatory cytokines (TNF-α and IL-6) in CRC cells via directly targeting TLR4. The protective effect of miR-6869-5p from colorectal carcinogenesis was dependent on TLR4/NF-κB signaling pathway. In addition, the 3-year survival was poor among CRC patients with decreased levels of miR-6869-5p in serum exosomes. Thus, miR-6869-5p may serve as a tumor suppressor in CRC, and serum exosomal miR-6869-5p is a promising circulating biomarker for the prediction of CRC prognosis.