Establishment and Evaluation of a Simple Size-Selective Method for Exosome Enrichment and Purification

Procedures for enrichment, isolation and purification of exosomes from complex biological samples are difficult, tedious, non-standardized, and require bulky instrumentation such as ultracentrifugation (UC). In this article, a simple method for isolating exosomes. Size-Selective Method (SSM) was established based on commercially available materials, and the UC and ExoQuick-TC kits (EQkit) methods were compared in terms of morphology, particle size, quantity, Western Blot (WB), and extraction time. Results showed that all three different exosome separation methods could obtain circular membranous vesicles, with a diameter of 30-110 nm. There were more non-exosome components in the samples extracted by SSM, such as large microvesicles, with a lower purity. UC obtained a large number of exosomes with a higher purity, but it required an ultracentrifuge, costed much time and had low yield. Both EQkit and SSM were easy to operate, but EQkit tended to aggregate exosomes and consume much time. WB results showed that exosomes extracted by all the three methods expressed CD63 protein. The SSM had the highest CD63 protein content and at the same protein concentration. The above evidences showed that SSM was fast and had high recovery, low cost and high protein concentration, but had more non-exosome protein components, which can be a choice for exosome separation.