Abstract and Introduction
Exosomes are nanoscale vesicles derived from endocytosis, formed by fusion of multivesicular bodies with membranes and secreted into the extracellular matrix or body fluids. Many studies have shown that exosomes can be present in a variety of biological fluids, such as plasma, urine, saliva, amniotic fluid, ascites, and sweat, and most types of cells can secrete exosomes. Exosomes play an important role in many aspects of human development, including immunity, cardiovascular diseases, neurodegenerative diseases, and neoplasia. Urine can be an alternative to blood or tissue samples as a potential source of disease biomarkers because of its simple, noninvasive, sufficient, and stable characteristics. Therefore, urinary exosomes have valuable potential for early screening, monitoring disease progression, prognosis, and treatment. The method for isolating urinary exosomes has been perfected, and exosome proteomics is widely used. Therefore, we review the potential use of urinary exosomes for disease diagnosis and summarize the related literature.
Exosomes are nanosized vesicles released after the fusion of multivesicular bodies with the cell membrane. The first biochemist to describe exosomes was Rose Johnstone in the 1980s. Johnstone reported a lipid-encapsulated particle with a diameter of 30 to 100 nm, which was produced due to downregulation of a specific membrane receptor during reticulocyte maturation. Since then, many exosome studies have been performed on bodily fluids, including blood, cerebrospinal fluid, urine, sweat, milk, synovial fluid, and pleural effusion.[2–6] The role of exosomes in cell-to-cell communication, immune regulation, and paracrine processes and the similarity of their contents to the cells of origin have aroused interest as potential sources of biomarkers. Urinary exosomes combine the advantages of exosomes and urine to provide a new noninvasive method to obtain information about the physiological or pathophysiological state of cells. Thus, urinary exosomes have attracted increasing attention in recent years.
Urine is an ideal source of protein markers for the detection of urinary tract–related diseases. It contains proteins secreted from the prostate, bladder, and kidneys and is produced by the lysis of exfoliated cells. Compared to blood, cerebrospinal fluid, ascites, pathological slices, and other samples, urine has unique advantages. Acquiring urine does not require the invasiveness of other liquid samples, avoids the infection risk of tissue biopsies, and allows continuous monitoring of the state of the body. In addition, the separation of exosomes can be a good way to note the enrichment of low-abundance proteins in urine, which has pathophysiological significance, and may become a biomarker with high sensitivity and specificity. The study of urinary exosomal proteins can provide clinicians with a simple, safe, and accurate method for detecting disease progression and monitoring treatment.
This review will briefly describe the origin and discovery of exosomes, summarize and analyze the isolation methods and potential applications of urinary exosomes, comprehensively introduce the latest research on urinary exosomes, and, finally, provide ideas and insights for further research on urinary exosomes.
Lab Med. 2023;54(2):115-125. © 2023 American Society for Clinical Pathology