Transcriptional arrest: Escherichia coli RNA polymerase translocates backward, leaving the 3′ end of the RNA intact and extruded

Abstract

Exosomes are circulating nanovesicular carriers of macromolecules, increasingly used for diagnostics and therapeutics. The ability to load and target patient-derived exosomes without altering exosomal surfaces is key to unlocking their therapeutic potential. We demonstrate that a peptide (CP05) identified by phage display enables targeting, cargo loading, and capture of exosomes from diverse origins, including patient-derived exosomes, through binding to CD63—an exosomal surface protein. Systemic administration of exosomes loaded with CP05-modified, dystrophin splice–correcting phosphorodiamidate morpholino oligomer (EXO_PMO) increased dystrophin protein 18-fold in quadriceps of dystrophin-deficient mdx mice compared to CP05-PMO. Loading CP05-muscle–targeting peptide on EXO_PMO further increased dystrophin expression in muscle with functional improvement without any detectable toxicity. Our study demonstrates that an exosomal anchor peptide enables direct, effective functionalization and capture of exosomes, thus providing a tool for exosome engineering, probing gene function in vivo, and targeted therapeutic drug delivery. Target acquired, anchors aweigh Small cell-derived, membrane-bound extracellular vesicles (exosomes) can be used therapeutically to deliver drugs or modify gene expression, but when given systemically it is difficult to target their distribution. Gao et al. developed a peptide, CP05, that binds to CD63, a protein expressed on exosomes. Painting exosomes with CP05 conjugated to a muscle-targeting peptide increased delivery of a splice-correcting oligomer to muscle, which increased dystrophin expression and muscle function in a mouse model of muscular dystrophy. CP05 could also isolate exosomes from human serum. This study demonstrates that CP05 can be used to capture and modify exosomes and their cargo for targeted delivery.