title: Modeling of congenital erythropoietic porphyria by RNA interference: a new tool for preclinical gene therapy evaluation.
abstract: BACKGROUND
  Congenital erythropoietic porphyria (CEP) is a severe autosomal recessive disorder characterized by a deficiency in uroporphyrinogen III synthase (UROS), the fourth enzyme of the heme biosynthetic pathway. We recently demonstrated the definitive cure of a murine model of CEP by lentiviral vector-mediated hematopoietic stem cell (HSC) gene therapy. In the perspective of a gene therapy clinical trial, human cellular models are required to evaluate the therapeutic potential of lentiviral vectors in UROS-deficient cells. However, the rare incidence of the disease makes difficult the availability of HSCs derived from patients.
  
  
  METHODS
  RNA interference (RNAi) has been used to develop a new human model of the disease from normal cord blood HSCs. Lentivectors were developed for this purpose.
  
  
  RESULTS
  We were able to down-regulate the level of human UROS in human cell lines and primary hematopoietic cells. A 97% reduction of UROS activity led to spontaneous uroporphyrin accumulation in human erythroid bone marrow cells of transplanted immune-deficient mice, recapitulating the phenotype of cells derived from patients. A strong RNAi-induced UROS inhibition allowed us to test the efficiency of different lentiviral vectors with the aim of selecting a safer vector. Restoration of UROS activity in these small hairpin RNA-transduced CD34(+) cord blood cells by therapeutic lentivectors led to a partial correction of the phenotype in vivo.
  
  
  CONCLUSIONS
  The RNAi strategy is an interesting new tool for preclinical gene therapy evaluation.
authors.affiliation: INSERM U876, Bordeaux, France.
authors.forename: Elodie
authors.initials: E
authors.lastname: Robert-Richard
authors.forename: Magalie
authors.initials: M
authors.lastname: Lalanne
authors.forename: Isabelle
authors.initials: I
authors.lastname: Lamrissi-Garcia
authors.forename: Véronique
authors.initials: V
authors.lastname: Guyonnet-Duperat
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Richard
authors.forename: Vincent
authors.initials: V
authors.lastname: Pitard
authors.forename: Fréderic
authors.initials: F
authors.lastname: Mazurier
authors.forename: François
authors.initials: F
authors.lastname: Moreau-Gaudry
authors.forename: Cécile
authors.initials: C
authors.lastname: Ged
authors.forename: Hubert
authors.initials: H
authors.lastname: de Verneuil
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D015316:Genetic Therapy / Q000379:methods*; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D006801:Humans; D020014:K562 Cells; D016086:Lentivirus / Q000235:genetics / Q000378:metabolism; D051379:Mice; D017092:Porphyria, Erythropoietic / Q000201:enzymology / Q000235:genetics / Q000628:therapy*; D034622:RNA Interference; D014576:Uroporphyrinogen III Synthetase / Q000235:genetics / Q000378:metabolism
chemical_list: D014576:Uroporphyrinogen III Synthetase