miR-451 Loaded Exosomes Are Released by the Renal Cells in Response to Injury and Associated With Reduced Kidney Function in Human

Urinary exosomal miRNA-451a can be used as a potential noninvasive biomarker for diagnosis, reflecting tubulointerstitial damage and therapeutic response in IgA nephropathy

To investigate the potential clinical value of urinary exosomal (uE) miR-451a as a biomarker for IgAN, urinary exosomes were isolated from 40 patients with IgAN, 30 patients with primary renal diseases without IgA as disease controls (non-IgAN group) and 21 healthy controls (HCs). The expression of miR-451a within exosomes was examined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). uE miR-451a was significantly upregulated in patients with IgAN compared to non-IgAN and HCs. The uE miR-451a level was positively correlated with the change in eGFR and negatively correlated with serum creatinine, urinary macrophage migration inhibitory factor (MIF), interleukin-6 (IL-6) and tumor necrosis factor (TNF-α). A dual-luciferase reporter assay confirmed that MIF was a direct target of miR-451a. Receiver operating characteristic (ROC) curve analysis revealed that the expression of uE miR-451a showed potential diagnostic value for IgAN. Additionally, the uE miR-451a level could distinguish patients with IgAN with mild tubular atrophy/interstitial fibrosis from those with severe tubular atrophy/interstitial fibrosis. After a mean follow-up of 14.2 months, the levels of eGFR loss (ml/min/1.73 m2/year) were negatively correlated with baseline miR-451a. The levels of baseline miR-451a in the complete remission group were significantly higher than those in the non-complete remission group. uE miR-451a expression was significantly elevated in patients with IgA nephropathy and may serve as a potential biomarker for the diagnosis of IgAN and evaluation of tubulointerstitial damage, while the baseline levels of uE miR-451a may be predictors of therapeutic efficacy and disease progression.

Extracellular vesicles in kidney development and pediatric kidney diseases

Extracellular vesicles (EVs) are membranous cargo particles that mediate intercellular communication. They are heterogeneous in size and mechanism of release, and found in all biological fluids. Since EV content is in relation to the originating cell type and to its physiopathological conditions, EVs are under study to understand organ physiology and pathology. In addition, EV surface cargo, or corona, can be influenced by the microenvironment, leading to the concept that EV-associated molecules can represent useful biomarkers for diseases. Recent studies also focus on the use of natural, engineered, or synthetic EVs for therapeutic purposes. This review highlights the role of EVs in kidney development, pediatric kidney diseases, including inherited disorders, and kidney transplantation. Although few studies exist, they have promising results and may guide researchers in this field. Main limitations, including the influence of age on EV analyses, are also discussed.

Understanding exosomes: Part 2-Emerging leaders in regenerative medicine

Exosomes are the smallest subset of extracellular signaling vesicles secreted by most cells with the ability to communicate with other tissues and cell types over long distances. Their use in regenerative medicine has gained tremendous momentum recently due to their ability to be utilized as therapeutic options for a wide array of diseases/conditions. Over 5000 publications are currently being published yearly on this topic, and this number is only expected to dramatically increase as novel therapeutic strategies continue to be developed. Today exosomes have been applied in numerous contexts including neurodegenerative disorders (Alzheimer's disease, central nervous system, depression, multiple sclerosis, Parkinson's disease, post-traumatic stress disorders, traumatic brain injury, peripheral nerve injury), damaged organs (heart, kidney, liver, stroke, myocardial infarctions, myocardial infarctions, ovaries), degenerative processes (atherosclerosis, diabetes, hematology disorders, musculoskeletal degeneration, osteoradionecrosis, respiratory disease), infectious diseases (COVID-19, hepatitis), regenerative procedures (antiaging, bone regeneration, cartilage/joint regeneration, osteoarthritis, cutaneous wounds, dental regeneration, dermatology/skin regeneration, erectile dysfunction, hair regrowth, intervertebral disc repair, spinal cord injury, vascular regeneration), and cancer therapy (breast, colorectal, gastric cancer and osteosarcomas), immune function (allergy, autoimmune disorders, immune regulation, inflammatory diseases, lupus, rheumatoid arthritis). This scoping review is a first of its kind aimed at summarizing the extensive regenerative potential of exosomes over a broad range of diseases and disorders.

Communication between nonalcoholic fatty liver disease and atherosclerosis: Focusing on exosomes

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic hepatic disorder on a global scale. Atherosclerosis (AS), a leading cause of cardiovascular diseases, stands as the primary contributor to mortality among patients diagnosed with NAFLD. However, the precise etiology by which NAFLD causes AS remains unclear. Exosomes are nanoscale extracellular vesicles secreted by cells, and are considered to participate in complex biological processes by promoting cell-to-cell and organ-to-organ communications. As vesicles containing protein, mRNA, non-coding RNA and other bioactive molecules, exosomes can participate in the development of NAFLD and AS respectively. Recently, studies have shown that NAFLD can also promote the development of AS via secreting exosomes. Herein, we summarized the recent advantages of exosomes in the pathogenesis of NAFLD and AS, and highlighted the role of exosomes in mediating the information exchange between NAFLD and AS. Further, we discussed how exosomes play a prominent role in enabling information exchange among diverse organs, delving into a novel avenue for investigating the link between diseases and their associated complications. The future directions and emerging challenges are also listed regarding the exosome-based therapeutic strategies for AS under NAFLD conditions.

Extracellular Vesicle MicroRNA in the Kidney

Most cells in our body release membrane-bound, nano-sized particles into the extracellular milieu through cellular metabolic processes. Various types of macromolecules, reflecting the physiological and pathological status of the producing cells, are packaged into such so-called extracellular vesicles (EVs), which can travel over a distance to target cells, thereby transmitting donor cell information. The short, noncoding ribonucleic acid (RNA) called microRNA (miRNA) takes a crucial part in EV-resident macromolecules. Notably, EVs transferring miRNAs can induce alterations in the gene expression profiles of the recipient cells, through genetically instructed, base-pairing interaction between the miRNAs and their target cell messenger RNAs (mRNAs), resulting in either nucleolytic decay or translational halt of the engaged mRNAs. As in other body fluids, EVs released in urine, termed urinary EVs (uEVs), carry specific sets of miRNA molecules, which indicate either normal or diseased states of the kidney, the principal source of uEVs. Studies have therefore been directed to elucidate the contents and biological roles of miRNAs in uEVs and moreover to utilize the gene regulatory properties of miRNA cargos in ameliorating kidney diseases through their delivery via engineered EVs. We here review the fundamental principles of the biology of EVs and miRNA as well as our current understanding of the biological roles and applications of EV-loaded miRNAs in the kidney. We further discuss the limitations of contemporary research approaches, suggesting future directions to overcome the difficulties to advance both the basic biological understanding of miRNAs in EVs and their clinical applications in treating kidney diseases. © 2023 American Physiological Society. Compr Physiol 13:4833-4850, 2023.

Therapeutic potential of urine exosomes derived from rats with diabetic kidney disease

Kidney disease is prevalent in diabetes. Urinary exosomes (uE) from animal models and patients with Diabetic nephropathy (DN) showed increased levels of miRs with reno-protective potential. We examined whether urinary loss of such miRs is associated with their reduced renal levels in DN patients. We also tested whether injecting uE can leverage kidney disease in rats. In this study (study-1) we performed microarray profiling of miRNA in uE and renal tissues in DN patients and subjects with diabetes without DN (controls). In study-2, diabetes was induced in Wistar rats by Streptozotocin (i.p. 50 mg/kg of body weight). Urinary exosomes were collected at 6th, 7th and 8th weeks, and injected back into the rats (100ug/biweekly, uE-treated n=7) via tail vein on weeks 9 and 10. Equal volume of vehicle was injected in controls (vehicle, n=7). uE from the human and rat showed the presence of exosome-specific proteins by immunoblotting. Microarray profiling revealed a set of 15 miRs having high levels in the uE, while lower in renal biopsies, from DN, compared to controls (n=5-9/group). Bioinformatic analysis also confirmed the Renoprotective potential of these miRs. Taqman qPCR confirmed the opposite regulation of miR-200c-3p and miR-24-3p in paired uE and renal biopsy samples from DN patients (n=15), relative to non-DN controls. A rise in 28 miRs levels, including miR-200c-3p, miR-24-3p, miR-30a-3p and miR-23a-3p were observed in the uE of DN rats, collected between 6th-8th weeks, relative to baseline (before diabetes induction). uE- treated DN rats had significantly reduced urine albumin-to-creatinine ratio, attenuated renal pathology, and lower miR-24-3p target fibrotic/inflammatory genes (TGF-beta, and Collagen IV), relative to vehicle treated DN rats. In uE treated rats, the renal expression of miR-24-3p, miR-30a-3p, let-7a-5p and miR-23a-3p was increased, relative to vehicle control. Patients with diabetic nephropathy had reduced renal levels, while higher uE abundance of miRs with reno-protective potential. Reverting the urinary loss of miRs by injecting uE attenuated renal pathology in diabetic rats.

miRNA Signature of Urine Extracellular Vesicles Shows the Involvement of Inflammatory and Apoptotic Processes in Diabetic Chronic Kidney Disease

BACKGROUND

The aim of this study was to investigate the role of urine-derived extracellular vesicles (uEVs) in diabetic kidney disease (DKD) in patients diagnosed with type 2 diabetes mellitus (T2DM).

METHODS

UEVs were characterized by size distribution and microRNA content by next-generation small RNA sequencing and quantitative reverse transcription PCR.

RESULTS

A subset of sixteen miRNAs enriched in T2DM patients with DKD, including hsa-miR-514a-5p, hsa-miR‑451a, hsa-miR-126-3p, hsa-miR-214, or hsa-miR‑503 was identified. Eight miRNAs as hsa-miR-21-3p, hsa-miR-4792, hsa-miR‑375, hsa-miR-1268a, hsa-miR-501-5p, or hsa-miR-582 were downregulated. Prediction of potential target genes and pathway enrichment analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) confirmed possible functions related to cellular processes such as apoptosis, inflammation, and tissue remodeling, that promote diabetic complications, such as DKD. Among them, hsa-miR-375, hsa-miR-503, and hsa-miR-451a make important contribution. Additionally, downregulated hsa-miR-582-5p has not been reported so far in any diabetes-related pathways.

CONCLUSIONS

This study revealed the most significant miRNAs in uEVs of patients with T2DM. However, as this is a bioinformatic prediction that we performed based on the putative targets of the identified miRNAs. Thus, further in vitro functional studies are needed to confirm our findings. Knowing the fact that EVs are crucial in transferring miRNAs, there is a great need toto discover their involvement in the pathomechanism of T2DM-related kidney disease.

Molecular profiling of urinary extracellular vesicles in chronic kidney disease and renal fibrosis

Chronic kidney disease (CKD) is a long-term kidney damage caused by gradual loss of essential kidney functions. A global health issue, CKD affects up to 16% of the population worldwide. Symptoms are often not apparent in the early stages, and if left untreated, CKD can progress to end-stage kidney disease (ESKD), also known as kidney failure, when the only possible treatments are dialysis and kidney transplantation. The end point of nearly all forms of CKD is kidney fibrosis, a process of unsuccessful wound-healing of kidney tissue. Detection of kidney fibrosis, therefore, often means detection of CKD. Renal biopsy remains the best test for renal scarring, despite being intrinsically limited by its invasiveness and sampling bias. Urine is a desirable source of fibrosis biomarkers as it can be easily obtained in a non-invasive way and in large volumes. Besides, urine contains biomolecules filtered through the glomeruli, mirroring the pathological state. There is, however, a problem of highly abundant urinary proteins that can mask rare disease biomarkers. Urinary extracellular vesicles (uEVs), which originate from renal cells and carry proteins, nucleic acids, and lipids, are an attractive source of potential rare CKD biomarkers. Their cargo consists of low-abundant proteins but highly concentrated in a nanosize-volume, as well as molecules too large to be filtered from plasma. Combining molecular profiling data (protein and miRNAs) of uEVs, isolated from patients affected by various forms of CKD, this review considers the possible diagnostic and prognostic value of uEVs biomarkers and their potential application in the translation of new experimental antifibrotic therapeutics.

What do we actually know about exosomal microRNAs in kidney diseases?

There are several types of kidney diseases with complex causes. If left untreated, these diseases irreversibly progress to end-stage renal disease. Thus, their early diagnosis and targeted treatment are important. Exosomes—extracellular vesicles released by a variety of cells—are ideal carriers for DNA, RNA, proteins, and other metabolites owing to their bilayer membranes. Studies have shown that almost all renal cells can secrete exosomes. While research on exosomal microRNAs in the context of renal diseases begun only recently, rapid progress has been achieved. This review summarizes the changes in exosomal microRNA expression in different kidney diseases. Thus, it highlights the diagnostic and prognostic value of these exosomal microRNAs. Further, this review analyzes their roles in the development of different kidney diseases, guiding research on molecular mechanisms and therapeutic strategies.

The divergent roles of exosomes in kidney diseases: Pathogenesis, diagnostics, prognostics and therapeutics

Exosomes are the self-packed nanoscale vesicles (nanovesicles) derived from late endosomes and released from the cells to the extracellular milieu. Exosomal biogenesis is based on endosomal pathway to form the nanovesicles surrounded by membrane originated from plasma membranes of the parental cells. During biogenesis, exosomes selectively encapsulate an array of biomolecules (proteins, nucleic acids, lipids, metabolites, etc.), thereby conveying diverse messages for cell-cell communications. Once released, these exosomal contents trigger signaling and trafficking that play roles in cell growth, development, immune responses, homeostasis, remodeling, etc. Recent advances in exosomal research have provided a wealth of useful information that enhances our knowledge on the roles for exosomes in pathogenic mechanisms of human diseases involving a wide variety of organ systems. In the kidney, exosomes play divergent roles, ranging from pathogenesis to therapeutics, based on their original sources and type of interventions. Herein, we summarize and update the current knowledge on the divergent roles of exosomes involving the pathogenesis, diagnostics, prognostics, and therapeutics in various groups of kidney diseases, including acute kidney injury, immune-mediated kidney diseases (e.g., IgA nephropathy, lupus nephritis, membranous nephropathy, focal segmental glomerulosclerosis), chronic kidney disease (caused by diabetic nephropathy and others), renal cell carcinoma, nephrolithiasis, kidney transplantation and related complications, and polycystic kidney disease. Finally, the future perspectives on research in this area are discussed.

Extracellular vesicles in kidney disease

Extracellular vesicles are released by the majority of cell types and circulate in body fluids. They function as a long-distance cell-to-cell communication mechanism that modulates the gene expression profile and fate of target cells. Increasing evidence has established a central role of extracellular vesicles in kidney physiology and pathology. Urinary extracellular vesicles mediate crosstalk between glomerular and tubular cells and between different segments of the tubule, whereas circulating extracellular vesicles mediate organ crosstalk and are involved in the amplification of kidney damage and inflammation. The molecular profile of extracellular vesicles reflects the type and pathophysiological status of the originating cell so could potentially be exploited for diagnostic and prognostic purposes. In addition, robust preclinical data suggest that administration of exogenous extracellular vesicles could promote kidney regeneration and reduce inflammation and fibrosis in acute and chronic kidney diseases. Stem cells are thought to be the most promising source of extracellular vesicles with regenerative activity. Extracellular vesicles are also attractive candidates for drug delivery and various engineering strategies are being investigated to alter their cargo and increase their efficacy. However, rigorous standardization and scalable production strategies will be necessary to enable the clinical application of extracellular vesicles as potential therapeutics.

In this Review, the authors discuss the roles of extracellular vesicles in kidney physiology and disease as well as the beneficial effects of stem cell-derived extracellular vesicles in preclinical models of acute kidney injury and chronic kidney disease. They also highlight current and future clinical applications of extracellular vesicles in kidney diseases.

Urinary extracellular vesicles have roles in intra-glomerular, glomerulo-tubular and intra-tubular crosstalk, whereas circulating extracellular vesicles might mediate organ crosstalk; these mechanisms could amplify kidney damage and contribute to disease progression.

Urinary extracellular vesicles could potentially be analysed using multiplex diagnostic platforms to identify pathological processes and the originating cell types; technological advances including single extracellular vesicle analysis might increase the specificity of bulk analysis of extracellular vesicle preparations.

Robust standardization and validation in large patient cohorts are required to enable clinical application of extracellular vesicle-based biomarkers.

Stem cell-derived extracellular vesicles have been shown to improve renal recovery, limit progression of injury and reduce fibrosis in animal models of acute kidney injury and chronic kidney disease.

Various engineering approaches can be used to load extracellular vesicles with therapeutic molecules and increase their delivery to the kidney.

A small clinical trial that tested the efficacy of mesenchymal stem cell extracellular vesicle administration in patients with chronic kidney disease reported promising results; however, therapeutic application of extracellular vesicles is limited by a lack of scalable manufacturing protocols and clear criteria for standardization.

Reduced insulin signaling and high glucagon in early insulin resistance impaired fast-fed regulation of renal gluconeogenesis via insulin receptor substrate

Gluconeogenesis is one of the key processes through which the kidney contributes to glucose homeostasis. Urinary exosomes (uE) have been used to study renal gene regulation noninvasively in humans and rodents. Recently, we demonstrated fast-fed regulation of phosphoenolpyruvate carboxykinase (PEPCK), the rate-limiting enzyme for gluconeogenesis, in human uE. The regulation was impaired in subjects with early insulin resistance. Here, we studied primary human proximal tubule cells (hPT) and human uE to elucidate a potential link between insulin resistance and fast-fed regulation of renal PEPCK. We demonstrate that fasted hPTs had higher PEPCK and insulin receptor substrate-2 (IRS2) mRNA and protein levels, relative to fed cells. The fast-fed regulation was, however, attenuated in insulin receptor knockdown (IRKO) hPTs. The IRKO was confirmed by the blunted insulin-induced response on PEPCK, PGC1α, p-IR, and p-AKT expression in IRKO cells. Exosomes secreted by the wild-type or IRKO hPT showed similar regulation to the respective hPT. Similarly, in human uE, the relative abundance of IRS-2 mRNA (to IRS1) was higher in the fasted state relative to the fed condition. However, the fast-fed difference was absent in subjects with early insulin resistance. These subjects had higher circulating glucagon levels relative to subjects with optimal insulin sensitivity. Furthermore, in hPT cells, glucagon significantly induced PEPCK and IRS2 gene, and gluconeogenesis. IR knockdown in hPT cells further increased the gene expression levels. Together the data suggest that reduced insulin sensitivity and high glucagon in early insulin resistance may impair renal gluconeogenesis via IRS2 regulation.

Emerging Biomarkers for Early Detection of Chronic Kidney Disease

Chronic kidney disease (CKD) is a major and serious global health problem that leads to kidney damage as well as multiple systemic diseases. Early diagnosis and treatment are two major measures to prevent further deterioration of kidney function and to delay adverse outcomes. However, the paucity of early, predictive and noninvasive biomarkers has undermined our ability to promptly detect and treat this common clinical condition which affects more than 10% of the population worldwide. Despite all limitations, kidney function is still measured by serum creatinine, cystatin C, and albuminuria, as well as estimating glomerular filtration rate using different equations. This review aims to provide comprehensive insight into diagnostic methods available for early detection of CKD. In the review, we discuss the following topics: (i) markers of glomerular injury; (ii) markers of tubulointerstitial injury; (iii) the role of omics; (iv) the role of microbiota; (v) and finally, the role of microRNA in the early detection of CKD. Despite all novel findings, none of these biomarkers have met the criteria of an ideal early marker. Since the central role in CKD progression is the proximal tubule (PT), most data from the literature have analyzed biomarkers of PT injury, such as KIM-1 (kidney injury molecule-1), NGAL (neutrophil gelatinase-associated lipocalin), and L-FABP (liver fatty acid-binding protein).

To the Future: The Role of Exosome-Derived microRNAs as Markers, Mediators, and Therapies for Endothelial Dysfunction in Type 2 Diabetes Mellitus

The prevalence of diabetes mellitus (DM) is increasing at a staggering rate around the world. In the United States, more than 30.3 million Americans have DM. Type 2 diabetes mellitus (T2DM) accounts for 91.2% of diabetic cases and disproportionately affects African Americans and Hispanics. T2DM is a major risk factor for cardiovascular disease (CVD) and is the leading cause of morbidity and mortality among diabetic patients. While significant advances in T2DM treatment have been made, intensive glucose control has failed to reduce the development of macro and microvascular related deaths in this group. This highlights the need to further elucidate the underlying molecular mechanisms contributing to CVD in the setting of T2DM. Endothelial dysfunction (ED) plays an important role in the development of diabetes-induced vascular complications, including CVD and diabetic nephropathy (DN). Thus, the endothelium provides a lucrative means to investigate the molecular events involved in the development of vascular complications associated with T2DM. microRNAs (miRNA) participate in numerous cellular responses, including mediating messages in vascular homeostasis. Exosomes are small extracellular vesicles (40-160 nanometers) that are abundant in circulation and can deliver various molecules, including miRNAs, from donor to recipient cells to facilitate cell-to-cell communication. Endothelial cells are in constant contact with exosomes (and exosomal content) that can induce a functional response. This review discusses the modulatory role of exosomal miRNAs and proteins in diabetes-induced endothelial dysfunction, highlighting the significance of miRNAs as markers, mediators, and potential therapeutic interventions to ameliorate ED in this patient group.

Targeted extracellular vesicle delivery systems employing superparamagnetic iron oxide nanoparticles

In the past decade, the study of extracellular vesicles (EVs), especially exosomes (50-150 nm) have attracted growing interest in numerous areas of cancer and tissue regeneration due to their unique biological features. A low isolation yield and insufficient targeting abilities limit their therapeutic applicability. Recently, superparamagnetic iron oxide nanoparticles (SPIONs) with magnetic navigation have been exploited to enhance the targeting ability of EVs. To construct targeted EV delivery systems engineered by SPIONs, several groups have pioneered the use of different techniques, such as electroporation, natural incubation, and cell extrusion, to directly internalize SPIONs into EVs. Furthermore, some endogenous ligands, such as transferrins, antibodies, aptamers, and streptavidin, were shown to enable modification of SPIONs, which increases binding with EVs. In this review, we summarized recent advances in targeted EV delivery systems engineered by SPIONs and focused on the key methodological approaches and the current applications of magnetic EVs. This report aims to address the existing challenges and provide comprehensive insights into targeted EV delivery systems. STATEMENT OF SIGNIFICANCE: Targeted extracellular vesicle (EV) delivery systems engineered by superparamagnetic iron oxide nanoparticles (SPIONs) have attracted wide attention and research interest in recent years. Such strategies employ external magnet fields to manipulate SPION-functionalized EVs remotely, aiming to enhance their accumulation and penetration in vivo. Although iron oxide nanoparticle laden EVs are interesting, they are controversial at present, hampering the progress in their clinical application. A thorough integration of these studies is needed for an advanced insight and rational design of targeted EV delivery systems. In this review, we summarize the latest advances in the design strategies of targeted EV delivery systems engineered by SPIONs with a focus on their key methodological approaches, current applications, limitation and future perspectives, which may facilitate the development of natural theranostic nanoplatforms.

Exosomes: Emerging Therapy Delivery Tools and Biomarkers for Kidney Diseases

Exosomes are nanometer-sized small EVs coated with bilayer structure, which are released by prokaryotic and eukaryotic cells. Exosomes are rich in a variety of biologically active substances, such as proteins, nucleotides, and lipids. Exosomes are widely present in various body fluids and cell culture supernatants, and it mediates the physiological and pathological processes of the body through the shuttle of these active ingredients to target cells. In recent years, studies have shown that exosomes from a variety of cell sources can play a beneficial role in acute and chronic kidney disease. In particular, exosomes derived from mesenchymal stem cells have significant curative effects on the prevention and treatment of kidney disease in preclinical trials. Besides, some encapsulated substances are demonstrated to exert beneficial effects on various diseases, so they have attracted much attention. In addition, exosomes have extensive sources, stable biological activity, and good biocompatibility and are easy to store and transport; these advantages endow exosomes with superior diagnostic value. With the rapid development of liquid biopsy technology related to exosomes, the application of exosomes in the rapid diagnosis of kidney disease has become more prominent. In this review, the latest development of exosomes, including the biosynthesis process, the isolation and identification methods of exosomes are systematically summarized. The utilization of exosomes in diagnosis and their positive effects in the repair of kidney dysfunction are discussed, along with the specific mechanisms. This review is expected to be helpful for relevant studies and to provide insight into future applications in clinical practice.

Exosomes in Nephropathies: A Rich Source of Novel Biomarkers

The biomarkers commonly utilized in diagnostic evaluations of kidney disease suffer from low sensitivity, especially in the early stages of renal damage. On the other hand, obtaining a renal biopsy to augment clinical decision making can lead to potentially serious complications. In order to overcome the shortcomings of currently available diagnostic tools, recent studies suggest that exosomes, cell-secreted extracellular vesicles containing a large array of active molecules to facilitate cell-to-cell communication, may represent a rich source of novel disease biomarkers. Because of their endocytic origin, exosomes carry markers typical for their parent cells, which could permit the localization of biochemical cellular alterations in specific kidney compartments. Different types of exosomes can be isolated from noninvasively obtained biofluids; however, in the context of kidney disease, evidence has emerged on the role of urinary exosomes in the diagnostic and predictive modeling of renal pathology. The current review summarizes the potential application of exosomes in the detection of acute and chronic inflammatory, metabolic, degenerative, and genetic renal diseases.