Scalable isolation of surface-engineered extracellular vesicles and separation of free proteins via tangential flow filtration and size exclusion chromatography (TFF-SEC)

Abstract

BackgroundExtracellular vesicles (EVs) represent small lipid bilayer structures pivotal in mediating intercellular communication via biomolecular transfer. Their inherent characteristics, including packaging, non-immunogenicity, and biofluid stability, position EVs as promising drug delivery vectors. However, developing clinical quality EVs requires multifaceted technological advancement.MethodsIn this study, a method is introduced for engineering extracellular vesicles (eEVs) from cultured cells and their subsequent isolation using lab-scale tangential flow filtration (TFF). This is the first study to evaluate DNA loading efficacy into EVs isolated by TFF, marking a significant milestone in the field of targeted drug delivery. Initially, cells are transfected with EV-display constructs to facilitate the secretion of eEVs bearing the desired coding molecules. Following brief centrifugation, the cell culture media undergoes filtration using hollow fiber filters. TFF, by applying a constant flow, effectively segregates molecules based on designated molecular weight cut-off (MWCO), enriching particles between 50 and 650 nm.ResultsCompared to conventional methods like ultracentrifugation, TFF demonstrates higher efficiency in removing undesired molecules/aggregates while exerting less stress on EVs. Characterization of eEVs through various assays confirms TFF’s superiority in isolating pure EV populations. Additionally, the necessity of size-exclusion chromatography (SEC) after tangential flow filtration (TFF) becomes evident for effectively removing unbound protein contaminants.ConclusionIn conclusion, TFF-SEC emerges as a scalable and superior approach for eEV isolation, promising significant advancements in clinical applications.