Urinary Exosomes in Nephrology: A New Frontier for Diagnosis and Prognosis of Kidney Diseases

Exosomes are nanosized vesicles that carry intracellular mediators and their abundance in urine opens new and intriguing possibilities in nephrology since they provide a non-invasive insight into kidney diseases. The aim of this review is to examine the main applications of urinary exosomes in nephropathies. Urinary exosomes are isolated through ultrafiltration, ultracentrifugation, precipitation, and immunoaffinity chromatography. After isolation they are characterized through Western blotting, flow cytometry, and, more recently, with mass spectrometry. Through the analysis of urinary exosomes, it has been possible to distinguish patients with IgA nephropathy from healthy controls. Different profiles of expression have been identified between patients with MCD and FSGS. A distinct exosomal composition has been discovered in patients with lupus nephropathy when compared to those without renal involvement. Significant findings have been reported also in patients with monoclonal gammopathy of renal significance, allowing a differential diagnosis between LCDD and amyloidosis. Among kidney transplant recipients, the analysis of urinary exosomes highlighted differences between antibody-mediated rejection and cell-mediated rejection. Urinary exosomes are new non-invasive, promising biomarkers and potential therapeutic options that have already shown interesting results in the nephrological field. Further studies are needed to harness their potential and diffusion.