The safe and effective delivery of drugs is a major obstacle in the treatment of ischemic stroke. Exosomes hold great promise as an endogenous drug delivery nanosystem for the treatment of cerebral ischemia given their unique properties, including low immunogenicity, innate stability, high delivery efficiency, and ability to cross the blood-brain barrier (BBB). However, exosome insufficient targeting capability limits their clinical applications. In this study, researchers from Nanjing Medical University conjugated the c(RGDyK) peptide to the exosome surface by an easy, rapid, and bio-orthogonal chemistry. In the transient middle cerebral artery occlusion (MCAO) mice model, The engineered c(RGDyK)-conjugated exosomes (cRGD-Exo) target the lesion region of the ischemic brain after intravenous administration. Furthermore, curcumin has been loaded onto the cRGD-Exo, and administration of these exosomes has resulted in a strong suppression of the inflammatory response and cellular apoptosis in the lesion region. The results suggest a targeting delivery vehicle for ischemic brain based on exosomes and provide a strategy for the rapid and large-scale production of functionalized exosomes.
Modification and characterization of exosomes
(A) Transmission electron micrograph of unmodified exosomes and the cRGD-Exo. Scale bar, 100 nm. (B) Size distribution of unmodified exosomes and the cRGD-Exo measured from TEM images. (C) Western blot analysis of Alix, TSG101, and Calnexin from MSCs and exosomes isolated from their conditioned medium. The supernatant obtained from the ultracentrifugation during exosome isolation was used as a negative control. (D) Schematic diagram of conjugating c(RGDyK) and Cy5.5 fluorophor to exosomal amine groups by a two-step reaction. (E) AFM images of unmodified exosomes and the cRGD-Exo. Upper graphs show peak force error images. Lower graphs present 3D height sensor images. Scale bar, 1 μm. (F) Statistics of the size of exosomes based on ten AFM images. Data are shown as mean ± SD. (G) Size distributions of unmodified exosomes and the cRGD-Exo based on NTA measurements.