What are the challenges of existing exosome isolation techniques?

The biggest challenge of existing exosome isolation techniques is the persistence of contaminants such as microsomes, lipoprotein particles, protein aggregates, microvesicles, and microbes during the isolation process. The presence of these contaminants makes it difficult to characterize exosomes accurately for use in downstream applications and other assays. 

The inconsistency in the results caused by improper storage conditions, such as freezing, poses another challenge in existing exosome isolation techniques. 

Another challenge is the lack of consistent and specific techniques for isolating and detecting an enriched subpopulation of nano-sized exosomes. It is important to have a comprehensive strategy that facilitates the precise separation of different exosome subpopulations based on biophysical and biochemical characteristics. 

Unknown characteristics of exosomes makes it difficult for scientists to choose the best-matched control for heterogeneous samples, which poses another challenge in exosome research.