Microfluidics-based molecular profiling of tumor-derived exosomes for liquid biopsy

Exosomes are extracellular vesicles that actively secreted by most live cells via endosome pathway. They distribute ubiquitously in body fluids and play important roles in physiological and pathological processes. Recent studies have revealed that exosomes carry cell-specific cargoes, such as proteins and nucleic acids, which have been recognized as emerging noninvasive biomarkers in liquid biopsy. Therefore, the molecular profiling of tumor-derived exosomes is crucial in facilitating the discovery of cancer-related biomarkers. Recently, various techniques have been proposed for sensitive, accurate, and rapid molecular characterization of these small vesicles. To meet the growing demands for multiplexed detection, microfluidics has been integrated with diverse traditional analytical methods as powerful components for exosomes analysis. Taking advantages of their inherent merits of great sensitivity, high analysis performance and system integration, short analysis time, low cost, small volume of sample, improved potential for control, automation, and disposability, microfluidic systems have significantly improved the molecular profiling of exosomes. In this review, we summarized the most recent progresses in microfluidic technologies for molecular profiling of tumor-derived exosomes, including proteins, nucleic acids, metabolites, lipids. Furthermore, we discussed the major challenges and offered a perspective of the microfluidic strategy-based exosomal biomarkers discovery. We expected that the in-depth summary of microfluidic devices-assisted analysis of exosomes will greatly facilitate the discovery of biomarkers, thereby realizing highly efficient and accurate diagnosis, and prediction of cancers. Moreover, in view of the significance of this interesting approach in exosomes-based liquid biopsy, this review will contribute to the translation of microfluidic technology into clinical applications.