Oral Presentation Australasian Extracellular Vesicles Conference 2020

Cancer exosomes are nanoscale membranous vesicles shed from cancer cells and are found to act as messergers of important information for cell-cell communication. Therefore, exosomes have been regarded as an important cancer biomarker used for cancer diagnosis. However, due to the high heterogeneity and low level of exosomes in body fluids, it is very challenging for sensitive and accurate detection of exosomes at molecular level. We proposed a sensitive and effective approach by using surface enhanced Raman scattering (SERS) nanotags for simultaneously profiling of multiple protein biomarkers expressed on cancer exosomes, without complex exosome isolation procedures. Rapid and multiplexed phenotypic profiling of exosomes are achieved by combining specific detection antibody-coated SERS nanotags as signal readout and the capture of antibody-conjugated magnetic beads for targets enrichment, which formed a sandwich structure (fig.1). As a proof-of-concept demonstration, we applied this approach to characterize pancreatic cancer derived exosomes by simultaneously detecting three specific exosomal surface receptors, including Glypican-1, EpCAM and CD44V6. The detection limit of this method is down to 2.3×10⁶ exosomes/mL, which is more sensitive and has shown much higher multiplex capacity than most of the reported profiling techniques. Furthermore, phenotypic profiling of exosomes from colorectal cancer and bladder cancer cell lines (SW480 and C3) was compared to that on pancreatic cancer exosomes, indicating the different exosomal phenotypes for different cancer types. Thus, we believe this technology enables a comprehensive evaluation of exosome secretion heterogeneity, which holds strong potential for non-invasive cancer diagnosis.