Bottom-up assembly of synthetic extracellular vesicles for biomedical applications

Scientists from the Max-Planck-Institute for Medical Research developed a bottom-up approach that allows the assembly of synthetic EVs in a two-step process. First, small unilamellar vesicles (around 100 nm in diameter) are formed from commercially available synthetic lipids according to the desired lipid composition by dehydration and rehydration. By tuning the lipid composition, vesicles of different charge and mechanical properties can be designed and fluorescent lipids can be included. These small vesicles can then be fused into larger vesicles of about 500 nm up to several micrometers in diameter by using a surfactant-stabilized water in oil emulsion. During this step, hydrophilic molecules, such as soluble drugs, dyes or nucleic acids, can be encapsulated into the aqueous lumen of the vesicles. After release of the vesicles from the surrounding oil phase, their surface is modified with recombinant proteins or extracellular domains thereof. Different strategies for protein binding are available including His tag binding to NTA(Ni²⁺)-functionalized lipids as well as Biotin-Streptavidin or NHS chemistry-based binding. In principle, reconstitution of transmembrane proteins into the vesicles could also be considered. This approach allows us to precisely control the lipid and protein composition as well as encapsulated compounds of the synthetic EVs.

Therefore, a bottom-up approach to assemble synthetic EVs from chemical building blocks can offer a faster, more precisely defined, reproducible and scalable approach to engineer many different types of synthetic EVs for different biomedical applications.

A European priority establishing patent application was submitted in January 2020 and followed by a PCT application in 2021.

Staufer et al., Bottom-up assembly of biomedical relevant fully synthetic extracellular vesicles, Science Advances 2021, 7(36)