A novel surface functionalization platform to prime extracellular vesicles for targeted therapy and diagnostic imaging

Extracellular vesicles (EVs), nanovesicles released by cells to effectively exchange biological information, are gaining interest as drug delivery system. Yet, analogously to liposomes, they show short blood circulation times and accumulation in the liver and the spleen. For tissue specific delivery, EV surfaces will thus have to be functionalized. We present a novel platform for flexible modification of EVs with target-specific ligands based on the avidin-biotin system. Genetic engineering of donor cells with a glycosylphosphatidylinositol-anchored avidin (GPI-Av) construct allows the isolation of EVs displaying avidin on their surface, functionalized with any biotinylated ligand. For proof of concept, GPI-Av EVs were modified with i) a biotinylated antibody or ii) de novo designed and synthesized biotinylated ligands binding carbonic anhydrase IX (CAIX), a membrane associated enzyme overexpressed in cancer. Functionalized EVs showed specific binding and uptake by CAIX-expressing cells, demonstrating the power of the system to prepare EVs for cell-specific drug delivery.