Sustained expression and safety of human GNE in normal mice after gene transfer based on AAV8 systemic delivery

GNE myopathy is an autosomal recessive adult onset disorder caused by mutations in the GNE gene. GNE encodes the bifunctional enzyme UDP-N-acetylglucosamine 2-epimerase/N-acetyl mannosamine kinase, the key enzyme in the biosynthesis pathway of sialic acid. Additional functions for GNE have been described recently, but the mechanism leading from GNE mutation to this myopathy is unclear. Therefore a gene therapy approach could address all potential defects caused by GNE mutations in muscle. We show that AAV8 viral vectors carrying wild type human GNE cDNA are able to transduce murine muscle cells and human GNE myopathy-derived muscle cells in culture and to express the transgene in these cells. Furthermore, the intravenous administration of this viral vector to healthy mice allows expression of the GNE transgene mRNA and of the coexpressed luciferase protein, for at least 6 months in skeletal muscles, with no clinical or pathological signs of focal or general toxicity, neither from the virus particles nor from the wild type human GNE overexpression. Our results support the future use of an AAV8 based vector platform for a safe and efficient therapy of muscle in GNE myopathy.