Exosomes for Non-Invasive Cancer Monitoring

Exosomes, membrane-bound phospholipid vesicles having diameters of 50-200 nm, are secreted by all cell types and circulate in human body fluids. These vesicles are known to carry cellular constituents that are specific to the originating cells (e.g., cytoplasmic/membrane proteins, RNA, and DNA). Thus, exosomes, which are both structurally stable and abundant, are robust indicators of cancers and, as a result, they have been utilized to monitor this disease in a manner that is less invasive than gold standard tissue biopsies. In this review, the history of exosomes and the specific biomarkers present in exosomes that enable accurate monitoring of various diseases are described. In addition, methods for analysis of exosomes and identification of biomarkers are presented with special emphasis being given to isolation and signaling strategies. Lastly, integrated, microfluidic systems developed for exosome-based cancer diagnosis are described and future directions that research in this area will likely take are presented.