Quantification and Analysis of Cancer-Cell Derived Exosomes

Over 90% of cancer-related deaths are due to metastasis. Tumor-cell derived extracellular vesicles or exosomes are thought to contribute to metastasis. However, there is no standardized method to isolate exosomes. We hypothesize that polymer-based kits, in particular ExoQuick-TC (EQTC), may be better for isolating exosomes when compared to ultracentrifugation. In this study, we used three different methods to isolate exosomes from 4T1 murine mammary tumor cells. Samples isolated through ultracentrifugation (UC), EQTC, and Total Exosome Isolation Reagent (TEIR) were analyzed to assess quantity and quality of exosomes by nanoparticle tracking analysis (NTA) and flow cytometry (FC). Using NTA, we found that each method yielded samples with varying average concentration and particle size. FC analysis revealed UC to be the most effective method in yielding a high number of verified exosomes. Standardizing the isolation method and assessment will help in determining the role of exosomes in cancer metastasis.