Figure 2. PEG-based vesicle enrichment is comparable or superior to standard harvest methods.

(a) All harvest methods recovered more particles than differential centrifugation (DC). (b) Particle sizes were consistent with the reported size distributions of exosomes. (c) The average sample purity of the 8% PEG + wash group was not statistically different from the DC group (p > 0.05), but was purer than those of the commercial products (p < 0.01). (d) Of the PEG-based methods, 8% PEG + wash and 12% PEG + wash produced the strongest evidence of exosomes by western blot. (e) Western analyses showed that purity of 8% PEG + wash group was comparable to DC, and superior to commercial methods. (f,g) Ponceau staining demonstrated that no method removed all serum protein contaminants, however, the 8% PEG + wash method greatly reduced the most prominent contaminants relative to other treatments. *A non-specific >50 kDa band appeared in the ExoQuick sample lane (d). It was subsequently confirmed to not reflect the presence of TSG101 (see Fig. 3). TEI, Total Exosome Isolation (Life Technologies). All approximate protein masses are represented in kilodaltons (kDa).