Safe and bodywide muscle transduction in young adult Duchenne muscular dystrophy dogs with adeno-associated virus

Abstract

The ultimate goal of muscular dystrophy gene therapy is to treat all muscles in the body. Global gene delivery was demonstrated in dystrophic mice more than a decade ago using adeno-associated virus (AAV). However, translation to affected large mammals has been challenging. The only reported attempt was performed in newborn Duchenne muscular dystrophy (DMD) dogs. Unfortunately, AAV injection resulted in growth delay, muscle atrophy and contracture. Here we report safe and bodywide AAV delivery in juvenile DMD dogs. Three ∼2-m-old affected dogs received intravenous injection of a tyrosine-engineered AAV-9 reporter or micro-dystrophin (μDys) vector at the doses of 1.92-6.24 × 10(14) viral genome particles/kg under transient or sustained immune suppression. DMD dogs tolerated injection well and their growth was not altered. Hematology and blood biochemistry were unremarkable. No adverse reactions were observed. Widespread muscle transduction was seen in skeletal muscle, the diaphragm and heart for at least 4 months (the end of the study). Nominal expression was detected in internal organs. Improvement in muscle histology was observed in μDys-treated dogs. In summary, systemic AAV gene transfer is safe and efficient in young adult dystrophic large mammals. This may translate to bodywide gene therapy in pediatric patients in the future.

Employment of Microencapsulated Sertoli Cells as a New Tool to Treat Duchenne Muscular Dystrophy

“…AAV vectors carried mini-or micro-dystrophins (i.e., different reduced parts of the DMD gene that still result in functional forms of the protein) have been used to treat animal models of DMD and DMD patients [19,27]. AAV vectors carrying minigenes have been injected in mdx mice and GRMD dogs demonstrating the efficient therapeutic effects of this treatment [28][29][30]. However, a phase I clinical trial using AAV-mini-dystrophin revealed only limited dystrophin expression and irrelevant muscle improvements due to the potential presence of AAV-neutralizing antibodies already present in humans, and the immune response against non-self-dystrophin [31], which requires this kind of approach be accompanied by immunosuppressive therapy.…”

A compact unc45b‐promoter drives muscle‐specific expression in zebrafish and mouse

“…Most muscle‐specific promoters such as that of the muscle creatine kinase (MCK) gene are very large (6.5 kb), and thus incompatible with AAVs having a 4.5 kb capacity (Wu et al ., 2010). Efforts have been made to shorten the MCK promoter, giving rise to the dMTK (509 bp) or tMCK (720 bp) promoter that show skeletal muscle‐specific expression (Yue et al ., 2015) and the MHCK7 (770 bp) promoter that drives cardiac and skeletal muscle expression (Salva et al ., 2007). …”

Effects of systemic multiexon skipping with peptide-conjugated morpholinos in the heart of a dog model of Duchenne muscular dystrophy

“…Adeno-associated virus vector-mediated gene therapy has enabled induction of minidystrophin in the heart of a dystrophic dog model (14,15). As another promising solution, PMOs conjugated with cell-penetrating peptides (CPPs) have been developed to induce dystrophin expression more effectively in bodywide muscles including the heart (16)(17)(18)(19).…”