Immunomagnetic Sequential Ultrafiltration (iSUF) Platform for Enrichment and Purification of Extracellular Vesicles from Biofluids

Extracellular vesicles (EVs) derived from tumor cells have the potential to provide a much-needed source of non-invasive molecular biomarkers for liquid biopsies. However, current methods for EV isolation have limited specificity towards tumor-derived EVs that limit their clinical use. Here, we present an approach called immunomagnetic sequential ultrafiltration (iSUF) that consists of sequential stages of purification and enrichment of EVs (nonspecifically and specifically) in approximately 2 h. In iSUF, EVs present in different volumes of biofluids (0.5 mL to 100 mL) can be significantly enriched (up to 1000 times), with up to 99 % removal of contaminating proteins (e.g., albumin). The EV recovery rate by iSUF for cell culture media (CCM), serum, and urine corresponded to 98.0% {+/-} 3.6%, 96.0% {+/-} 2.0% and 94.0% {+/-} 1.9%, respectively (p > 0.05). The final step of iSUF enables the separation of tumor-specific EVs by incorporating immunomagnetic beads specific to a target subpopulation of EVs. Serum from a small cohort of clinical samples from metastatic breast cancer (BC) patients and healthy donors were processed by the iSUF platform and the isolated EVs from patients showed significantly higher expression levels of BC biomarkers (i.e., HER2, CD24, and miR21).