Development and comparative analysis of human urine exosome isolation strategies

Exosomes contain virtually every type of biomolecules that have originated from parental cells. High concentrations of exosomes are found in a variety of body fluids including urine, a body fluid that can be easily and non-invasively collected. Therefore, urinary exosomes are ideal materials for liquid biopsy. Although there are some major barriers to their use which include high variability and lack of standarization of exosome isolation methods. Therefore, it is highly recommended to systemically assess urinary exosome isolation strategies in terms of isolation concentration and purity. In this study, comparative studies among eight different strategies based on ultracentrifugation, ultrafiltration, precipitation, and size exclusion chromatography (SEC) were performed for urinary exosome isolation from healthy donors. The results indicated that SEC combined with ultrafiltration was the most compromised and balanced method for urinary exosome isolation in terms of both isolation concentration and purity. SEC combined with precipitation yielded the highest purity. Thus, the appropriate urinary exosome isolation method can be chosen depending on the downstream applications of isolated urinary exosomes. This comparative analysis of urinary exosome isolation methods contributes to the discovery of exosome-associated biomarker and the development of exosome-based diagnostics.