Origin Of Exosomes Research Articles

Exosomal non coding RNAs as a novel target for diabetes mellitus and its complications.

Diabetes mellitus (DM) is a first-line priority among the problems facing medical science and public health in almost all countries of the world. The main problem of DM is the high incidence of damage to the cardiovascular system, which in turn leads to diseases such as myocardial infarction, stroke, gangrene of the lower extremities, blindness and chronic renal failure. As a result, the study of the molecular genetic mechanisms of the pathogenesis of DM is of critical importance for the development of new diagnostic and therapeutic strategies. Molecular genetic aspects of the etiology and pathogenesis of diabetes mellitus are intensively studied in well-known laboratories around the world. One of the strategies in this direction is to study the role of exosomes in the pathogenesis of DM. Exosomes are microscopic extracellular vesicles with a diameter of 30-100nm, released into the intercellular space by cells of various tissues and organs. The content of exosomes depends on the cell type and includes mRNA, non-coding RNAs, DNA, and so on. Non-coding RNAs, a group of RNAs with limited transcriptional activity, have been discovered to play a significant role in regulating gene expression through epigenetic and posttranscriptional modulation, such as silencing of messenger RNA. One of the problems of usage exosomes in DM is the identification of the cellular origin of exosomes and the standardization of protocols for molecular genetic studies in clinical laboratories. In addition, the question of the target orientation of exosomes and their targeted activity requires additional study. Solving these and other problems will make it possible to use exosomes for the diagnosis and delivery of drugs directly to target cells in DM. This study presents an analysis of literature data on the role of exosomes and ncRNAs in the development and progression of DM, as well as the prospects for the use of exosomes in clinical practice in this disease.

The combination of Alisma and Atractylodes ameliorates cerebral ischaemia/reperfusion injury by negatively regulating astrocyte-derived exosomal miR-200a-3p/141-3p by targeting SIRT1

Ethnopharmacological relevanceThe combination of Alisma and Atractylodes (AA), a classical traditional Chinese herbal decoction, may protect against cerebral ischaemia/reperfusion injury (CIRI). However, the underlying mechanism has not been characterized. Intriguingly, exosomal microRNAs (miRNAs) have been recognized as vital factors in the pharmacology of Chinese herbal decoctions. Aim of the studyThe aim of the present study was to assess whether the neuroprotective effect of AA was dependent on the efficient transfer of miRNAs via exosomes in the brain. Materials and methodsBilateral common carotid artery ligation (BCAL) was used to induce transient global cerebral ischaemia/reperfusion (GCI/R) in C57BL/6 mice treated with/without AA. Neurological deficits were assessed with the modified neurological severity score (mNSS) and Morris water maze (MWM) test. Western blot (WB) analysis was used to detect the expression of sirtuin 1 (SIRT1) in the cerebral cortex. The inflammatory state was quantitatively evaluated by measuring the expression of phospho-Nuclear factor kappa B (p–NF–κB), Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) using WB analysis and glial fibrillary acidic protein (GFAP) immunohistochemical staining. The protein expression of zonula occluden-1 (ZO-1), occludin, caudin-5 and CD31 was examined by immunohistochemical staining to determine blood‒brain barrier (BBB) permeability. Exosomes were extracted from the brain interstitial space by ultracentrifugation and identified by transmission electron microscopy (TEM), WB analysis and nanoparticle tracking analysis (NTA). The origin of exosomes was clarified by measuring the specific mRNAs within exosomes via Real Time Quantitative PCR (RT‒qPCR). Differential miRNAs in exosomes were identified using microarray screening and were validated by RT‒qPCR. Exosomes were labelled with fluorescent dye (PKH26) and incubated with bEnd.3 cells, the supernatant was collected, IL-1β/TNF-α expression was measured using enzyme-linked immunosorbent assay (ELISA), total RNA was extracted, and miR-200a-3p/141-3p expression was examined by RT‒qPCR. In addition, the levels of miR-200a-3p/141-3p in oxygen glucose deprivation/reoxygenation (OGD/R)-induced bEnd.3 cells were quantified. The direct interaction between miR-200a-3p/141-3p and the SIRT1 3′ untranslated region (3′UTR) was measured by determining SIRT1 expression in bEnd.3 cells transfected with the miR-200a-3p/141-3p mimic/inhibitor. ResultsSevere neurological deficits and memory loss caused by GCI/R in mice was markedly ameliorated by AA treatment, particularly in the AA medium-dose group. Moreover, AA-treated GCI/R-induced mice showed significant increases in SIRT1, ZO-1, occludin, caudin-5, and CD31 expression levels and decreases in p–NF–κB, IL-1β, TNF-α, and GFAP expression levels compared with those in untreated GCI/R-induced mice. Furthermore, we found that miR-200a-3p/141-3p was enriched in astrocyte-derived exosomes from GCI/R-induced mice and could be inhibited by treatment with a medium dose of AA. The exosomes mediated the transfer of miR-200a-3p/141-3p into bEnd.3 cells, promoted IL-1β and TNF-α release and downregulated the expression of SIRT1. No significant changes in the levels of miR-200a-3p/141-3p were observed in OGD/R-induced bEnd.3 cells. The miR-200a-3p/141-3p mimic/inhibitor decreased/increased SIRT1 expression in bEnd.3 cells, respectively. ConclusionOur findings demonstrated that AA attenuated inflammation-mediated CIRI by inhibiting astrocyte-derived exosomal miR-200a-3p/141-3p by targeting the SIRT1 gene, which provided further evidence and identified a novel regulatory mechanism for the neuroprotective effects of AA.

Giant Enhancement of Raman Scattering by a Hollow-Core Microstructured Optical Fiber Allows Single Exosome Probing.

Microstructured optical fibers (MOFs) provide solutions for breaking through the bottlenecks in areas of high-power transmission and high-efficiency optical waveguides. Other than transporting light waves, MOFs can synergistically combine microfluidics and optics in a single fiber with an unprecedented light path length not readily achievable by planar optofluidic configurations. Here, we demonstrate that hollow-core anti-resonant optical fibers (HcARFs) can significantly enhance Raman scattering by over three orders of magnitude (EF ≈ 5000) compared with a planar setup, due to the joint mechanisms of strong light-matter interaction in the fiber core and the cumulative effect of the fiber. The giant enhancement enables us to develop the first optical fiber sensor to achieve single cancer exosome detection via a sandwich-structured strategy. This enables a multiplexed analysis of surface proteins of exosome samples, potentially allowing an accurate identification of the cellular origin of exosomes for cancer diagnosis. Our findings could expand the applications of HcARF in many exciting areas beyond the waveguide.

Exosomes: The role in mammalian reproductive regulation and pregnancy-related diseases.

Exosomes are a kind of extracellular vesicles that are produced and secreted by different mammalian cells. They serve as cargo proteins and can transfer different kinds of biomolecules, including proteins, lipids, and nucleic acids, which consequently act on target cells to exert different biological effects. Recent years have witnessed a significant increase in the number of studies on exosomes due to the potential effects of exosomes in the diagnosis and treatment of cancers, neurodegenerative diseases, and immune disorders. Previous studies have demonstrated that exosomal contents, especially miRNAs, are implicated in numerous physiological processes such as reproduction, and are crucial regulators of mammalian reproduction and pregnancy-related diseases. Here, we describe the origin, composition, and intercellular communication of exosomes, and discuss their functions in follicular development, early embryonic development, embryonic implantation, male reproduction and development of pregnancy-related diseases in humans and animals. We believe this study will provide a foundation for revealing the mechanism of exosomes in regulating mammalian reproduction, and providing new approaches and ideas for the diagnosis and treatment of pregnancy-related diseases.

Exosomal circular RNAs: A chief culprit in cancer chemotherapy resistance.

Chemotherapy is one of the primary treatments for malignant tumors. However, the acquired drug resistance hinders clinical efficacy and leads to treatment failure in most patients. Exosomes are cell-derived vesicles with a diameter of 30-150nm carrying and delivering substances such as DNAs, RNAs, lipids, and proteins for cellular communication in tumor development. Circular RNAs (circRNAs) present covalently closed-loop RNA structures, which regulate tumor cell proliferation, apoptosis, and metastasis by controlling different genes and signaling pathways. CircRNAs are abundant and stably expressed in exosomes. Recent studies have shown that they play critical roles in chemotherapy resistance in various cancers. In this review, we summarized the origin of exosomes and discussed the regulation mechanism of exosomal circRNAs in cancer drug resistance.

Origin and Composition of Exosomes as Crucial Factors in Designing Drug Delivery Systems

Exosomes are a subpopulation of extravascular vesicles with a diameter of 30–150 nm. They are cellular-communication mediators, often reaching very distant organism tissues. Information is transferred by exosomal cargo, composed of a wide variety of macromolecules such as nucleic acids, proteins, and lipids. Exosomes possess natural specific cell targeting properties that are desirable in designing targeted macromolecules (DNA and RNA) and drug delivery systems (doxorubicin, paclitaxel, and taxol). In this context, exosomes can be defined as bio-derived drug transporting and protecting devices for the treatment of bacterial (toxoplasmosis and salmonellosis), viral (AIDS and hepatitis B), and cancer (lung, pancreatic, colon, brain, and breast) diseases. Extensive research proves that exosomes’ natural cargo can double-act, both increasing and decreasing the disease severity. In this case, the exosomes need to be prepared, namely, their origin and their cargo need to be screened and known. Thus, appropriate methods for intact and price-effective exosome isolation are needed with further exosome properties description. Among many utilized isolation methods, the most common are ultracentrifugation, polymer-based precipitation, and affinity precipitation-isolation systems, but novel microfluidic methods compromising high efficacy and purity are being developed. In this review, we state the current knowledge and trends in exosome-based drug delivery systems.

Milk exosomes as delivery agents for therapy of cancer diseases

Exosomes are natural nanovesicles with a diameter of 40–100 nm, which are actively involved in the transfer of biologically active substances and participate in intercellular communication. The natural origin of exosomes determines its biological compatibility with cell cultures and makes them promising delivery vehicles for anticancer drugs. Methods of the artificial production of exosomes are not available, and exosome preparations obtained from tumor cells are not suitable for therapy. Milk is a biological fluid that is commercially available and may be a universal source of exosomes for treatment. Target delivery of anticancer drugs using milk exosomes can reduce the toxic effect of cytostatic agents during chemotherapy. This review discusses methods for isolating exosomes from milk, their additional purification, and analysis of their biologically significant components – proteins and nucleic acids, and prospects for using milk exosomes to treat cancer.

Nanoplasmonic Sensor Approaches for Sensitive Detection of Disease-Associated Exosomes.

Exosomes are abundantly secreted by most cells that carry membrane and cytosolic factors that can reflect the physiologic state of their source cells and thus have strong potential to serve as biomarkers for early diagnosis, disease staging, and treatment monitoring. However, traditional diagnostic or prognostic applications that might use exosomes are hindered by the lack of rapid and sensitive assays that can exploit their biological information. An array of assay approaches have been developed to address this deficit, including those that integrate immunoassays with nanoplasmonic sensors to measure changes in optical refractive indexes in response to the binding of low concentrations of their targeted molecules. These sensors take advantage of enhanced and tunable interactions between the electron clouds of nanoplasmonic particles and structures and incident electromagnetic radiation to enable isolation-free and ultrasensitive quantification of disease-associated exosome biomarkers present in complex biological samples. These unique advantages make nanoplasmonic sensing one of the most competitive approaches available for clinical applications and point-of-care tests that evaluate exosome-based biomarkers. This review will briefly summarize the origin and clinical utility of exosomes and the limitations of current isolation and analysis approaches before reviewing the specific advantages and limitations of nanoplasmonic sensing devices and indicating what additional developments are necessary to allow the translation of these approaches into clinical applications.

Review of Methodological Approaches to Human Milk Small Extracellular Vesicle Proteomics.

Proteomics can map extracellular vesicles (EVs), including exosomes, across disease states between organisms and cell types. Due to the diverse origin and cargo of EVs, tailoring methodological and analytical techniques can support the reproducibility of results. Proteomics scans are sensitive to in-sample contaminants, which can be retained during EV isolation procedures. Contaminants can also arise from the biological origin of exosomes, such as the lipid-rich environment in human milk. Human milk (HM) EVs and exosomes are emerging as a research interest in health and disease, though the experimental characterization and functional assays remain varied. Past studies of HM EV proteomes have used data-dependent acquisition methods for protein detection, however, improvements in data independent acquisition could allow for previously undetected EV proteins to be identified by mass spectrometry. Depending on the research question, only a specific population of proteins can be compared and measured using isotope and other labelling techniques. In this review, we summarize published HM EV proteomics protocols and suggest a methodological workflow with the end-goal of effective and reproducible analysis of human milk EV proteomes.

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

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

Exosome a Story From Waste to Become a Gold Mine

: Exosomes are emerging as a novel therapeutic avenue which is exploring. These naturally made nanoparticles are mainly used by cells to communicate. Given that they are composed of a lipid layer and the macromolecules that they carry inside, including lipids, proteins, and microRNA, can be considered as good candidates for drug and gene delivery. However, the source of exosomes to be used in the clinic needs to be investigated, as they are naturally made by cells, and they quickly can move through the body without being recognized by the immune system. In this review, we tried to bring the recent breakthroughs for exosome isolation, characterization, and therapeutic use. We discussed the origin of exosomes, their composition, and their potential for clinical use as a targeted gene and drug delivery systems.

Exosome-based Tumor Therapy: Opportunities and Challenges.

Exosomes play an important role in transferring information among different cell types, as they transport materials from the cell membrane to the cytoplasm. They are involved not only in normal physiological functions, but also in the occurrence and development of a variety of diseases. Cancer is a major health problem affecting humans. Currently, exosomes are considered novel stars in tumor therapy. To present a review focusing on the role of exosomes in tumorigenesis and development and the possibility of treating tumors with exosome-targeted therapies or using exosomes as carriers. We reviewed literature related to the biological origin and function of exosomes and exosome-tumor relationship. Exosomes are closely related to tumor immunity, angiogenesis, pre-metastasis microenvironment, chemoresistance, energy metabolism, etc. Tumor therapy involving the targeting of exosomes involves block the generation, secretion, uptake of exosomes, and elimination of circulating exosomes, and develop antitumor vaccines. Exosome as delivery vehicles can be loaded with chemotherapeutic drugs, therapeutic genes, and other therapeutic drugs to target cells. Prospects and challenges of exosome-based tumor therapy are also discussed. Exosomes are involved in multiple processes during tumor development and should be further studied as novel targets for cancer therapy.

Proteomic Analysis Reveals Proteins and Pathways Associated with Lactation in Bovine Mammary Epithelial Cell-Derived Exosomes.

Milk-derived exosomes have been reported, which are involved in many biological processes. The exosomes derived from mammary glands are not known yet, and their relationship with mammary gland lactation and the origin of milk-derived exosomes are largely unclear. The present study aimed to investigate the proteome of exosomes derived from bovine mammary epithelial cells (BMECs) and compare them with milk-derived exosomes in the database. BMEC-derived exosomes were successfully separated from the culture supernatant of BMECs by a combined ultracentrifugation approach, and the purity of exosomes was identified by western blot analysis. Liquid chromatography with tandem mass spectrometry identified 638 proteins in BMEC-derived exosomes. The MS data were deposited into the PUBLIC repository ProteomeXchange, dataset identifier(s): https://www.iprox.org/page/PSV023.html;?url=1590961453176tKpa. Gene Ontology annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that these proteins were associated with specific biological processes and molecular functions of metabolism. Cross comparison of these proteins with the protein database of milk exosomes showed that 77 common expressed proteins (CEPs) were in both BMEC- and milk-derived exosomes. The KEGG pathway analysis for these CEPs showed that they were mainly involved in signaling pathways associated with milk biosynthesis in BMECs. Among these CEPs, six proteins have been previously reported to be associated with the lactation function. The western blot analysis detected that expression of these six proteins in BMEC-derived exosomes was increased after the stimulation of methionine and β-estradiol on BMECs. In summary, the proteome of BMEC-derived exosomes reveals that they are associated with milk biosynthesis in BMECs and might be a source of milk-derived exosomes.

SUN-045 URINARY EXTRACELLULAR VESICLES AS BIOMARKER OF RENAL TUBULAR INJURY

Extracellular vesicles (EV) are microstructures that participate in cellular communication. They are released by all biological fluids and are carriers of proteins, lipids, DNA, RNA mainly miRNA, that reflect their cell of origin. Among their populations, we can mention microvesicles and exosomes. Exosomes are structures that are 40-150 nm and have preserved proteins, such tetraspanins CD9, CD63 and CD81. They are released after injury, including in acute renal injury. Urinary exosomes (uEV) are potential marker of renal tubular injury. However, few studies have confirmed the origin of exosomes excreted in the urine. This study aims to compare the clearance of fluorescent beads similar to exosomes with the clearance of inulin and creatinine, substances excreted in the urine only by glomerular filtration. This strategy aims to determine whether uEV come from the kidney itself or from systemic origin through glomerular filtration and/or tubular secretion. Wistar rats were anesthetized, submitted to an intrajugular injection of inulin (10%) or fluorescent beads (0.1%). Serum and urine samples were collected before and 2h after the beginning of the experiment. The clearance of inulin, creatinine and fluorescent beads were determined by respective quantifications in serum and urine samples. Creatinine and inulin concentrations were determined by spectrophotometry and beads concentrations were determined by fluorescence quantification by Nanoparticle Tracking Analysis (NTA). The location of beads in renal tissue was determined by immunofluorescence microscopy. According to the NTA method, the beads commercially obtained had a diameter of 97 nm, consistent with the exosomes. There was no significant difference between creatinine clearances in the group inulin (1.13 ± 0.31 mL/min) or beads (1.13 ± 0.17 mL/min) at the end of the experiment, suggesting that administration of the particles did not alter renal function. On the contrary, at the end of the experiment, the clearance of beads was significantly lower (0.26 ± 0.26 mL/min) than inulin clearance (2.02 ± 0.29 mL/min), suggesting that particles of similar diameter to exosomes are poorly filtered by the glomerulus. Additionally, we identified the beads in the glomerulus and peritubular space, demonstrating their presence in the kidney. However, we observed an increase in the clearance of non-fluorescent particles compared to fluorescent ones, suggesting that most of the uEVs come from the urinary system itself. This work suggests that uEVs released in the urine come from the urinary system itself, reinforcing its potential as a biomarker for kidney diseases, like acute kidney injury and renal tubular injury.

Exosomes From Astrocyte Processes: Signaling to Neurons.

It is widely recognized that extracellular vesicles subserve non-classical signal transmission in the central nervous system. Here we assess if the astrocyte processes, that are recognized to play crucial roles in intercellular communication at the synapses and in neuron-astrocyte networks, could convey messages through extracellular vesicles. Our findings indicate, for the first time that freshly isolated astrocyte processes prepared from adult rat cerebral cortex, can indeed participate to signal transmission in central nervous system by releasing exosomes that by volume transmission might target near or long-distance sites. It is noteworthy that the exosomes released from the astrocyte processes proved ability to selectively target neurons. The astrocyte-derived exosomes were proven positive for neuroglobin, a protein functioning as neuroprotectant against cell insult; the possibility that exosomes might transfer neuroglobin to neurons would add a mechanism to the potential astrocytic neuroprotectant activity. Notably, the exosomes released from the processes of astrocytes maintained markers, which prove their parental astrocytic origin. This potentially allows the assessment of the cellular origin of exosomes that might be recovered from body fluids.

A High Efficient Method to Isolate Exosomes from Small Intestinal Epithelium.

The intestinal epithelium is an important receptor that is not only exposed to nutrients but also to pathogens, such as ingested toxins, bacterial flora, and their metabolites. The sensory information is communicated to extensive endocrine, neural, immune systems, and the exosomes acts as carriers of communication from cell-to-cell. Isolation of exosomes from small intestinal epithelium remains more complex to obtain as a source of exosomes, as it contains varying proportions of exosomes derived from many different cells. Current studies on exosomes have been largely performed using supernatants of cultured cells. This is because, in a cell culture, the origin of exosomes can be determined and isolation of exosomes devoid of 'contaminating' proteins, lipids, and sugars involves relatively simple composition of most culture media facilitates. However, this is hard to achieve in intestinal epithelial cells (IECs) due to several technical issues, including recapitulation of in vivo physiology, operational simplicity, culture stability over time, and assay throughput. Meanwhile, separation of exosomes from a specific cell type remains to be a considerable problem, as the isolated supernatant exosomal fraction may represent only a small fraction of the total instead of reflecting the overall situation. Herein, we proposed an efficient protocol for enrichment of exosomes from the interstitial space of small intestinal epithelium. This method maintains the integrity of the vesicles as well as their contents. Also, it may help to better understand the properties of exosomes and explore their role in cell-to-cell communication of small intestinal epithelium.

Near-Infrared Afterglow Semiconducting Nano-Polycomplexes for the Multiplex Differentiation of Cancer Exosomes.

The detection of exosomes is promising for the early diagnosis of cancer. However, the development of suitable optical sensors remains challenging. We have developed the first luminescent nanosensor for the multiplex differentiation of cancer exosomes that bypasses real-time light excitation. The sensor is composed of a near-infrared semiconducting polyelectrolyte (ASPN) that forms a complex with a quencher-tagged aptamer. The afterglow signal of the nanocomplex (ASPNC), being initially quenched, is turned on in the presence of aptamer-targeted exosomes. Because detection of the afterglow takes place after the excitation, background signals are minimized, leading to an improved limit of detection that is nearly two orders of magnitude lower than that of fluorescence detection in cell culture media. Also, ASPNC can be easily tailored to detect different exosomal proteins by changing the aptamer sequence. This enables an orthogonal analysis of multiple exosome samples, potentially permitting an accurate identification of the cellular origin of exosomes for cancer diagnosis.

Near‐Infrared Afterglow Semiconducting Nano‐Polycomplexes for the Multiplex Differentiation of Cancer Exosomes

AbstractThe detection of exosomes is promising for the early diagnosis of cancer. However, the development of suitable optical sensors remains challenging. We have developed the first luminescent nanosensor for the multiplex differentiation of cancer exosomes that bypasses real‐time light excitation. The sensor is composed of a near‐infrared semiconducting polyelectrolyte (ASPN) that forms a complex with a quencher‐tagged aptamer. The afterglow signal of the nanocomplex (ASPNC), being initially quenched, is turned on in the presence of aptamer‐targeted exosomes. Because detection of the afterglow takes place after the excitation, background signals are minimized, leading to an improved limit of detection that is nearly two orders of magnitude lower than that of fluorescence detection in cell culture media. Also, ASPNC can be easily tailored to detect different exosomal proteins by changing the aptamer sequence. This enables an orthogonal analysis of multiple exosome samples, potentially permitting an accurate identification of the cellular origin of exosomes for cancer diagnosis.

Exosomes: fighting cancer with cancer.

Exosomes are nanovesicles secreted by many cells, including cancer cells. Extensive research has been carried out to validate potential applications of exosomes and to evaluate their efficiency in a wide range of diseases, including cancer. The current knowledge on the origin, biogenesis and composition of exosomes is described. This review then focuses on the use of exosomes in cancer diagnostics and therapeutics.

Urinary Exosomes and Exosomal CCL2 mRNA as Biomarkers of Active Histologic Injury in IgA Nephropathy

IgA nephropathy (IgAN) features variable renal pathology and a heterogeneous clinical course. Our aim was to search noninvasive biomarkers from urinary exosomes for IgAN patients; membrane nephropathy and minimal change disease were included as other glomerulopathy controls. Transmission electron microscopy and nanoparticle tracking analysis confirmed the size and morphology characteristic of urinary exosomes. Exosome markers (Alix and CD63) as well as renal cell markers [aquaporin 2 (AQP2) and nephrin] were detected, which indicate the renal origin of urinary exosomes. Exosome excretion was increased markedly in IgAN patients compared with controls and correlated with levels of proteinuria and tubular injury. More important, urinary exosome excretion correlated with greater histologic activity (mesangial hypercellularity, crescents, and endocapillary hypercellularity). Profiling of the inflammation-related mRNA revealed that exosomal chemokine (C-C motif) ligand 2 (CCL2) was up-regulated in IgAN patients. In a validation study, CCL2 was exclusively highly expressed in IgAN patients compared with healthy controls as well as minimal change disease and membrane nephropathy patients. Also, a correlation between exosomal CCL2 and estimated glomerular filtration rate levels was found in IgAN. Exosomal CCL2 was correlated with tubulointerstitial inflammation and C3 deposition. High CCL2 levels at the time of renal biopsy were associated with subsequent deterioration in renal function. Thus, urinary exosomes and exosomal CCL2 mRNA are promising biomarkers reflecting active renal histologic injury and renal function deterioration in IgAN.