Metabolomic profiling of urine-derived extracellular vesicles from rat model of drug-induced acute kidney injury

Effects and Mechanisms of Extracellular Vesicles in Different Models of Acute Kidney Injury

Acute kidney injury (AKI) is a rapid decline in renal function caused by ischemia/reperfusion (I/R), renal toxic injury, and sepsis. While the precise molecular mechanisms underlying AKI are still under investigation, current therapeutic approaches remain insufficient. In recent years, there has been growing evidence that mesenchymal stem cells (MSCs) have great potential in accelerating renal repair after AKI in various preclinical models, while there has been extensive research on extracellular vesicles (EVs) as therapeutic mediators in AKI models, and they are considered to be superior to MSCs as new regenerative therapies. EVs are nanoparticles secreted by various types of cells under physiological and pathological conditions. EVs derived from various sources possess biomarker potential and play crucial roles in mediating cellular communication between kidney cells and other tissue cells by transmitting signal molecules. These vesicles play a direct and indirect role in regulating the pathophysiological mechanisms of AKI and contribute to the occurrence, development, treatment, and repair of AKI. In this review, we briefly outline the essential characteristics of EVs, focus on the multiple molecular mechanisms currently involved in the protection of EVs against different types of AKI, and further discuss the potential targets of EVs from different sources in the treatment of AKI. Finally, we summarized the deficiencies in the production and treatment of EVs and the current strategies for improvement.

Monitoring the electroactive cargo of extracellular vesicles can differentiate various cancer cell lines

Extracellular vesicles (EVs) are pivotal in cell-to-cell communication due to the array of cargo contained within these vesicles. EVs are considered important biomarkers for identification of disease, however most measurement approaches have focused on monitoring specific surface macromolecular targets. Our study focuses on exploring the electroactive component present within cargo from EVs obtained from various cancer and non-cancer cell lines using a disk carbon fiber microelectrode. Variations in the presence of oxidizable components were observed when the total cargo from EVs were measured, with the highest current detected in EVs from MCF7 cells. There were differences observed in the types of oxidizable species present within EVs from MCF7 and A549 cells. Single entity measurements showed clear spikes due to the detection of oxidizable cargo within EVs from MCF7 and A549 cells. These studies highlight the promise of monitoring EVs through the presence of varying electroactive components within the cargo and can drive a wave of new strategies towards specific detection of EVs for diagnosis and prognosis of various diseases.

Targeted protein quantitation in human body fluids by mass spectrometry

Human body fluids (biofluids) contain various proteins, some of which reflect individuals' physiological conditions or predict diseases. Therefore, the analysis of biofluids can provide substantial information on novel biomarkers for clinical diagnosis and prognosis. In the past decades, mass spectrometry (MS)-based technologies have been developed as proteomic strategies not only for the identification of protein biomarkers but also for biomarker verification/validation in body fluids for clinical applications. The main advantage of targeted MS-based methodologies is the accurate and specific simultaneous quantitation of multiple biomarkers with high sensitivity. Here, we review MS-based methodologies that are currently used for the targeted quantitation of protein components in human body fluids, especially in plasma, urine, cerebrospinal fluid, and saliva. In addition, the currently used MS-based methodologies are summarized with a specific focus on applicable clinical sample types, MS configurations, and acquisition modes.

Pre-analytical handling conditions and protein marker recovery from urine extracellular vesicles for bladder cancer diagnosis

Extracellular vesicles (EVs) contain a variety of biomolecules and provide information about the cells that produce them. EVs from cancer cells found in urine can be used as biomarkers to detect cancer, enabling early diagnosis and treatment. The potential of alpha-2-macroglobulin (A2M) and clusterin (CLU) as novel diagnostic urinary EV (uEV) biomarkers for bladder cancer (BC) was demonstrated previously. To validate the diagnostic value of these proteins in uEVs in a large BC cohort, urine handling conditions before uEV isolation should be optimized during sample transportation from medical centers. In this study, we analyzed the uEV protein quantity, EV particle number, and uEV-A2M/CLU after urine storage at 20°C and 4°C for 0-6 days, each. A2M and CLU levels in uEVs were relatively stable when stored at 4°C for a maximum of three days and at 20°C for up to 24 h, with minimal impact on analysis results. Interestingly, pre-processing to remove debris and cells by centrifugation and filtration of urine did not show any beneficial effects on the preservation of protein biomarkers of uEVs during storage. Here, the importance of optimizing shipping conditions to minimize the impact of pre-analytical handling on the uEVs protein biomarkers was emphasized. These findings provide insights for the development of clinical protocols that use uEVs for diagnostic purposes.

Metabolomics of Extracellular Vesicles: A Future Promise of Multiple Clinical Applications

Extracellular vesicles (EVs) can contain DNA, RNA, proteins and metabolic molecules from primary origins; they are coated with a phospholipid bilayer membrane and released by cells into the extracellular matrix. EVs can be obtained from various body liquids, including the blood, saliva, cerebrospinal fluid, and urine. As has been proved, EVs-mediated transfer of biologically active molecules is crucial for various physiological and pathological processes. Extensive investigations have already begun to explore the diagnosis and prognosis potentials for EVs. Furthermore, research has continued to recognize the critical role of nucleic acids and proteins in EVs. However, our understanding of the comprehensive effects of metabolites in these nanoparticles is currently limited and in its infancy. Therefore, we have attempted to summarize the recent research into the metabolomics of EVs in relation to potential clinical applications and discuss the problems and challenges that have occurred, to provide more guidance for the future development in this field.

Extracellular Vesicles as Theranostic Tools in Kidney Disease

Extracellular vesicles are important vectors for cell-cell communication and show potential value for diagnosis and treatment of kidney diseases. The pathologic diagnosis of kidney diseases relies on kidney biopsy, whereas collection of extracellular vesicles from urine or circulating blood may constitute a less invasive diagnostic tool. In particular, urinary extracellular vesicles released mainly from resident kidney cells might provide an alternative tool for detection of kidney injury. Because extracellular vesicles mirror many features of their parent cells, cargoes of several populations of urinary extracellular vesicles are promising biomarkers for disease processes, like diabetic kidney disease, kidney transplant, and lupus nephritis. Contrarily, extracellular vesicles derived from reparative cells, such as mesenchymal stem cells, tubular epithelial progenitor cells, and human umbilical cord blood represent promising regenerative tools for treatment of kidney diseases. Furthermore, induced pluripotent stem cells-derived and engineered extracellular vesicles are being developed for specific applications for the kidney. Nevertheless, some assumptions regarding the specificity and immunogenicity of extracellular vesicles remain to be established. This review focuses on the utility of extracellular vesicles as therapeutic and diagnostic (theranostic) tools in kidney diseases and future directions for studies.

Extracellular vesicles in renal inflammatory and infectious diseases

Extracellular vesicles can mediate cell-to-cell communication, or relieve the parent cell of harmful substances, in order to maintain cellular integrity. The content of extracellular vesicles includes miRNAs, mRNAs, growth factors, complement factors, cytokines, chemokines and receptors. These may contribute to inflammatory and infectious diseases by the exposure or transfer of potent effectors that induce vascular inflammation by leukocyte recruitment and thrombosis. Furthermore, vesicles release cytokines and induce their release from cells. Extracellular vesicles possess immune modulatory and anti-microbial properties, and induce receptor signaling in the recipient cell, not least by the transfer of pro-inflammatory receptors. Additionally, the vesicles may carry virulence factors systemically. Extracellular vesicles in blood and urine can contribute to the development of kidney diseases or exhibit protective effects. In this review we will describe the role of EVs in inflammation, thrombosis, immune modulation, angiogenesis, oxidative stress, renal tubular regeneration and infection. Furthermore, we will delineate their contribution to renal ischemia/reperfusion, vasculitis, glomerulonephritis, lupus nephritis, thrombotic microangiopathies, IgA nephropathy, acute kidney injury, urinary tract infections and renal transplantation. Due to their content of miRNAs and growth factors, or when loaded with nephroprotective modulators, extracellular vesicles have the potential to be used as therapeutics for renal regeneration.