Engineering a Switchable Nanosystem for Customizable Therapeutics

Exosomes are nanovesicles that are naturally secreted by mammalian cells in vivo for intercellular communications. Due to their inherent targeting ability, exosomes have a potential for therapeutic applications. However, due to their physiological derivation, the isolation of engineered exosomes has been a major obstacle to their therapeutic application, and successful disease-targeting has been difficult to control. Recently, we have developed an exosome technology that borrows from switchable Chimeric Antigen Receptor (sCAR) T-Cell Therapy and Strep-tag engineering to overcome these obstacles. Here, we describe the development of a de novo method to produce genetically modified exosomes with switchable targeting ability and easier isolation capacity. We have elected to fuse an exosome-anchoring protein, vesicular stomatitis viral glycoprotein (VSVG), with a peptide neoepitope (PNE) short-chain variable fragment (scFV) and a StrepTag region. The PNE-scFV will allow for switchable targeting while the Strep-tag will allow for enhanced purification abilities. We have shown that living human cells can produce the engineered exosomes, and we have isolated the engineered exosomes from producer cells. Post isolation, we have characterized these modified exosomes, and we have begun testing the functionality of the PNE scFV and StrepTag regions. This technology will broaden application of exosomes in a therapeutic setting.