Isolation and purification of exosomes in urine.

Exosomes represent an important and readily isolated subset of the urinary proteome that has the potential to shed much insight on the health status of the kidney. Each segment of the nephron sheds exosomes into the urine. Exosomes are rich in potential biomarkers, especially membrane proteins such as transporters and receptors that may be up- or downregulated during disease states. Two differential centrifugation methods are available for simple purification of exosomes: one uses ultracentrifugation, and the other uses a nanomembrane concentrator. Validation methods include western blots of pan-exosome markers and segment-specific exosome markers, and negative staining electron microscopy.