Bovine milk processing impacts characteristics of extracellular vesicle isolates obtained by size-exclusion chromatography

Abstract

Extracellular vesicles facilitate intercellular communication by transferring bioactive molecules with the potential to elicit host responses. Raw bovine milk contains functional extracellular vesicles that are taken up by humans. By comparing with extracellular vesicles from unprocessed bovine milk, the impact of pasteurisation, hydrodynamic cavitation treatment, or homogenisation on purity of milk extracellular vesicles isolated by a series of centrifugation steps followed by size-exclusion chromatography was assessed. Extracellular vesicles could be isolated from all four source materials, though to varying extents as evident from Western blots. In particular, homogenisation resulted in co-isolation of non-extracellular vesicle material such as β-casein, β-lactoglobulin, and triacylglycerol. RNA concentrations were highest in extracellular vesicles derived from the three processed source materials, thus indicating co-isolation of other RNA-containing detergent-labile particles in addition to native milk extracellular vesicles. Overall, this study shows that the history of milk processing impacts the purity of milk extracellular vesicles.