Oil Red O based method for exosome labelling and detection.

With the realization of the role of exosomes in diseases, especially cancer, exosome research is gaining popularity in biomedical sciences. To understand exosome biology, their labelling and tracking studies are important. New and improved methods of exosome labelling for detection and tracking of exosomes need to be developed to harness their therapeutic and diagnostic potential. In this paper, we report a novel, simple and effective method of labelling and detecting exosomes using Oil Red O (ORO), a dye commonly used for lipid staining. Using ORO is a cost effective and easy approach with an intense red coloration of exosomes. Further, the issues faced with commonly used lipophilic dyes for exosome labelling like long-term persistence of dyes, aggregation and micelle formation of dyes, difficulty in distinguishing dye particles from labelled exosomes, and detection of large aggregates of dye or dye-exosome, are also resolved with ORO dye. This method shows good labelling efficacy with very sensitive detection and real-time tracking of the cellular uptake of exosomes.