Comparison of differential ultracentrifugation (DC) and size exclusion chromatography (SEC) based exosome isolation methods

Introduction:

In order to challenge the current lack of an exosome isolation technique that can provide high quality exosomes without contamination from other biomolecules, we optimised a PEG/SEC isolation method and compared it with the classical DC isolation method, with regards to exosome yield, integrity, purity and biomolecular content.

Methods:

Exosomes of healthy donor plasma and cell lines were isolated by DC or SEC. They were evaluated for their exo-protein (BCA), size and number (NTA). EM was used to show their integrity and the samples were tested for specific exo-markers (WB). PCR and RT-PCR of nucleic acids was performed for the detection of specific mutations.

Results:

Plasma exosomes extracted by SEC showed higher yield, integrity and purity in comparison to exosomes isolated by DC. SEC-isolated cell line exosomes showed similar yield and purity to DC exosomes, but higher integrity. Detection of leukemia specific mutations in exo-dsDNA was possible.

Conclusion:

Our study shows the potential of using the SEC method to isolate exosomes for cancer biomarker development and functional research.