Table 1.
Strategy | Study Model | Mutation | Target Molecule | Carrier | Target Regions | Administration | Comments | Ref. |
---|---|---|---|---|---|---|---|---|
Skipping exons 45–55 | Primary DMD myotubes | DMD ex46–50 or ex48–50 del. | pre-mRNA | 2 or 12 2′-OMePSs | Ex45–55 | PEI transfection | First published attempt at ex45–55 skipping in vitro using DMD patient cells | [56] |
mdx52 mice | Dmd ex52 del. | pre-mRNA | 10 vivo-PMOs | Ex45–51, ex53–55 |
i.m. (TA) or i.v. | First demonstration of successful in vivo ex45–55 skipping treatment in mice | [42] | |
mdx52 mice | Dmd ex52 del. | pre-mRNA | 10 vivo-PMOs | Ex45–51, Ex53–55 |
i.m. (TA) or i.v. | Showed the long-term systemic efficacy and safety of ex45–55 skipping treatment in mice | [57] | |
Converted DMD myotubes | DMD ex46–50 del. | pre-mRNA | 6 PMOs | Ex45, Ex51–55 |
Endo-porter transfection | Demonstrated the feasibility of ex45–55 skipping in muscle cells transdifferentiated from patient fibroblasts and showed a possibility of tailored cocktail therapy | [58] | |
Converted DMD myotubes | DMD ex45–50 del. | pre-mRNA | 5 PMOs | Ex51–55 | Endo-porter transfection | |||
Deleting exons 45–55 | Immortalized DMD myotubes | DMD ex48–50 del. | DNA | CRISPR/Cas9 | Introns44, 55 | Plasmid electroporation: spCas9, 2 gRNAs | First study to successfully delete ex45–55 in vitro; NSG mice transplanted with treated myoblasts showed dystrophin-positive fibers | [59] |
DMD hiPSCs, hiPSC-derived myotubes, cardiomyocytes | DMD ex46–51 or 46–47 del., or ex50 dup. | DNA | CRISPR/Cas9 | Introns 44, 55 |
Plasmid nucleofection: spCas9, 2 gRNA | Restored dystrophin expression/functionality in patient hiPSCs and derivative cell types | [61] | |
DMD hiPSC-derived skeletal muscle cells | DMD ex46–51 del. | DNA | CRISPR/Cas9 | Introns 44, 55 |
Engraftment into NSG-mdx mice TAs | Muscles engrafted with treated hiPSC muscle cells showed proper dystrophin and beta-dystroglycan localization | ||
hDMD del. 45 mice | DMD ex45 del. | DNA | CRISPR/Cas9 | Introns 44, 55 |
Electroporation into FDB muscle | First to show dystrophin restoration in vivo in humanized dystrophic mice following ex45–55 deletion, without cell transplantation | [60] |
ex, exon; del., deletion; 2′-OMePS, 2′-O-methyl-phosphorothioate; PEI, polyethyleneimine; PMO, phosphorodiamidate morpholino oligomer; i.m., intramuscular injection; i.v., intravenous injection; del, deletion; dup, duplication; TA, tibialis anterior muscle; CRISPR/Cas9, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated nuclease (Cas) 9; spCas9, Streptococcus pyogenes Cas9; gRNA, a short guide RNA; hiPSCs, human induced pluripotent stem cell; NSG, NOD scid IL2R gamma; hDMD, a mouse model with the human DMD gene; FDB, flexor digitorum brevis muscle.