title: Prolonged expression of a lysosomal enzyme in mouse liver after Sleeping Beauty transposon-mediated gene delivery: implications for non-viral gene therapy of mucopolysaccharidoses.
abstract: BACKGROUND
  The Sleeping Beauty (SB) transposon system is a non-viral vector system that can integrate precise sequences into chromosomes. We evaluated the SB transposon system as a tool for gene therapy of mucopolysaccharidosis (MPS) types I and VII.
  
  
  METHODS
  We constructed SB transposon plasmids for high-level expression of human beta-glucuronidase (hGUSB) or alpha-L-iduronidase (hIDUA). Plasmids were delivered with and without SB transposase to mouse liver by rapid, high-volume tail-vein injection. We studied the duration of expressed therapeutic enzyme activity, transgene presence by PCR, lysosomal pathology by toluidine blue staining and cell-mediated immune response histologically and by immunohistochemical staining.
  
  
  RESULTS
  Transgene frequency, distribution of transgene and enzyme expression in liver and the level of transgenic enzyme required for amelioration of lysosomal pathology were estimated in MPS I and VII mice. Without immunomodulation, initial GUSB and IDUA activities in plasma reached > 100-fold of wild-type (WT) levels but fell to background within 4 weeks post-injection. In immunomodulated transposon-treated MPS I mice plasma IDUA persisted for over 3 months at up to 100-fold WT activity in one-third of MPS I mice, which was sufficient to reverse lysosomal pathology in the liver and, partially, in distant organs. Histological and immunohistochemical examination of liver sections in IDUA transposon-treated WT mice revealed inflammation 10 days post-injection consisting predominantly of mononuclear cells, some of which were CD4- or CD8-positive.
  
  
  CONCLUSIONS
  Our results demonstrate the feasibility of achieving prolonged expression of lysosomal enzymes in the liver and reversing MPS disease in adult mice with a single dose of therapeutic SB transposons.
authors.affiliation: Department of Genetics, Cell Biology and Development and the Arnold and Mabel Beckman Center for Transposon Research, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Elena L
authors.initials: EL
authors.lastname: Aronovich
authors.forename: Jason B
authors.initials: JB
authors.lastname: Bell
authors.forename: Lalitha R
authors.initials: LR
authors.lastname: Belur
authors.forename: Roland
authors.initials: R
authors.lastname: Gunther
authors.forename: Brenda
authors.initials: B
authors.lastname: Koniar
authors.forename: David C C
authors.initials: DC
authors.lastname: Erickson
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Schachern
authors.forename: Ilze
authors.initials: I
authors.lastname: Matise
authors.forename: R Scott
authors.initials: RS
authors.lastname: McIvor
authors.forename: Chester B
authors.initials: CB
authors.lastname: Whitley
authors.forename: Perry B
authors.initials: PB
authors.lastname: Hackett
mesh_terms: D000818:Animals; D004798:Enzymes / Q000008:administration & dosage / Q000235:genetics*; D015870:Gene Expression; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods; D007150:Immunohistochemistry; D007249:Inflammation; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D008247:Lysosomes / Q000201:enzymology* / Q000473:pathology; D051379:Mice; D009083:Mucopolysaccharidoses / Q000473:pathology / Q000628:therapy*; D019895:Transposases / Q000235:genetics*
chemical_list: D004798:Enzymes; D019895:Transposases; C494471:sleeping beauty transposase, human