Improved transduction of canine X-linked muscular dystrophy with rAAV9-microdystrophin via multipotent mesenchymal stromal cell pretreatment

Abstract Duchenne muscular dystrophy (DMD) is a severe congenital disease associated with mutation of the dystrophin gene. Supplementation of dystrophin using rAAV has promise as a treatment for DMD, although vector-related general toxicities, such as liver injury, neurotoxicity, germline transmission have been suggested in association with the systemic delivery of high doses of rAAV. Here, we treated normal or dystrophic dogs with rAAV9 transduction in conjunction with multipotent mesenchymal stromal cells (MSCs) injection to investigate the therapeutic effects of an rAAV expressing microdystrophin (μDys) under conditions of immune modulation. Bone marrow-derived MSCs, rAAV-CMV-μDys, and a rAAV-CAG-luciferase were injected into the jugular vein of a young dystrophic dog to induce systemic expression of μDys. One week after the first injection, the dog received a second intravenous injection of MSCs, and on the following day, rAAV was intravenously injected into the same dog. Systemic injection of rAAV9 with MSC pretreatment improves gene transfer into normal and dystrophic dogs. Dystrophic phenotypes significantly improved in the rAAV-μDys-injected dystrophic dog, suggesting that an improved rAAV-μDys treatment including immune modulation induces successful long-term transgene expression to improve dystrophic phenotypes.