BIOBRIEFPAPER
The Small paper reports an antibody free way to isolate extracellular vesicles — the cell's natural 'shipping parcels' — and a light triggered switch that releases cargo inside target cells, tested in primary human liver cells.
A Heidelberg team has built a cleaner production line for the cell's own "shipping parcels," engineering the outer scaffolding of extracellular vesicles so researchers can pull them out without antibodies and trigger their cargo release with a flash of light.
The method, published in Small by Pham, Lee, Ritter and colleagues at University Hospital Heidelberg, BioQuant and the German Cancer Research Center, inserts an internal twin-Strep affinity tag into the large extracellular loop of two canonical vesicle tetraspanins, CD63 and CD9. Strep-Tactin resin then captures intact vesicles directly, replacing antibody-based isolation. The result: proteomic analysis shows more than 96% of protein contaminants removed, the paper notes.
The same scaffolds carry a protein of interest fused at the C-terminus, optionally through a PhoCl2 photocleavable linker so researchers can time cargo release with light. A VSV-G coat helps delivered proteins escape the endosome after uptake, and the group showed the system clears hepatitis C virus and adeno-associated virus from preparations, then delivers functional proteins into primary human hepatocytes and hepatocyte-like cells.
The work is funded by Germany's DFG and the DZIF infectious-disease center, with no industry role. It is a methods advance, not a therapy: demonstrations are in vitro and ex vivo, and in vivo delivery, pharmacokinetics, and immunogenicity are not shown in this paper.