Cell-Penetrating Peptides Enhance Systemic Delivery of Antisense Morpholino Oligomers

Exon-skipping efficacy of phosphorodiamidate morpholino oligomers (Morpholinos) has been demonstrated in a proof-of-concept clinical trial for Duchenne muscular dystrophy (DMD). Systemic delivery of Morpholinos can be significantly enhanced by conjugating them to cell-penetrating peptides. The improved efficacy has been demonstrated in DMD animal models, including mdx mice and utrophin–dystrophin double-knockout mice. Compared to unconjugated Morpholinos, far lower doses of the �peptide–Morpholino conjugates can restore dystrophin sufficiently to reduce disease pathology, increase skeletal and cardiac muscle functions and prolong survival of animals. In addition, the conjugates enter cardiomyocytes in useful quantities and improve heart functions. Here, an experimental protocol for making Tat peptide–Morpholino conjugate is described.