Solving the Contamination Conundrum Derived from Coisolation of Extracellular Vesicles and Lipoproteins: Approaches for Isolation and Characterization

Extracellular vesicles (EVs) are nanoscale lipid-bilayer-enclosed particles released by most cell types, serving as pivotal mediators of intercellular communication, cargo transport, and immune regulation. Owing to their intrinsic biological functions and biocompatibility, EVs demonstrate tremendous potential in medical applications. However, a major challenge in EV research is the coisolation of lipoprotein (LP) contaminants, particularly plasma lipoproteins, during the purification of biofluids (e.g., plasma or serum) or cell culture supernatants. LPs and EVs exhibit substantial overlap in physicochemical properties, including particle size and density, which likely contributes to their coisolation. Notably, mutual-contamination between these two particle populations can significantly interfere with downstream analyses, leading to misinterpretation of their respective compositions and biological functions. Therefore, obtaining high-purity EV and LP isolates free from mutual contamination is crucial. To address this technical challenge, there is an urgent need to establish robust isolation methods and standardized characterization systems. This review systematically evaluates current EV/LP isolation technologies with varying separation specificities, while innovatively proposing characterization strategies capable of distinguishing EVs, LPs, and potential EV-LP complexes. By elucidating the "mutual-contamination" issues between these particles, it is aimed to promote and call for the establishment of stricter methodological standards in this field.