Exosomes, which are 30–150 nm extracellular vesicles containing a variety of biomolecules (i.e., proteins, RNA, DNA, and lipids), have emerged as important analytes in liquid biopsy. Although exosome detection offers a valuable chance to understand disease status in a multidimensional manner, comprehensive analysis of different exosomal biomolecules with limited specimens remains a challenge.
Researchers from the Chinese Academy of Sciences introduced an aptamer-based PCR (polymerase chain reaction) platform and realized highly sensitive detection of CD63 protein positive exosomes as low as 50 particles/μL. More importantly, simultaneous analysis of exosomal RNA and surface protein is available using this method. In a proof of concept experiment, simultaneous detection of two immunotherapy-related biomarkers, programmed death-ligand 1 (PD-L1) protein and indoleamine 2,3-dioxygenase 1 (IDO1) mRNA, was demonstrated with clinical samples. This method provides a strategy for the comprehensive analysis of exosomes, with the advantages of high sensitivity and practicability.