Ultracentrifugation versus kit exosome isolation: nanoLC-MS and other tools reveal similar performance biomarkers, but also contaminations.

Aim: For isolation of exosomes, differential ultracentrifugation and an isolation kit from a major vendor were compared.

Materials & methods: 'Case study' exosomes isolated from patient-derived cells from glioblastoma multiforme and a breast cancer cell line were analyzed.

Results: Transmission electron microscopy, dynamic light scattering, western blotting, and so forth, revealed comparable performance. Potential protein biomarkers for both diseases were also identified in the isolates using nanoLC-MS. Western blotting and nanoLC-MS also revealed negative exosome markers regarding both isolation approaches.

Conclusion: The two isolation methods had an overall similar performance, but we hesitate to use the term 'exosome isolation' as impurities may be present with both isolation methods. NanoLC-MS can detect disease biomarkers in exosomes and is useful for critical assessment of exosome enrichment procedures.