title: Sustained delivery of therapeutic concentrations of human clotting factor IX--a comparison of adenoviral and AAV vectors administered in utero.
abstract: BACKGROUND
  Prenatal somatic gene therapy has been considered for genetic disorders presenting with morbidity at birth. Haemophilia is associated with an increased risk of catastrophic perinatal bleeding complications such as intracranial haemorrhage, which could be prevented by gene transfer in utero. Prenatal gene therapy may be more promising than postnatal treatment, as the fetus may be more amenable to uptake and integration of therapeutic DNA and the immaturity of its immune system may permit life-long immune tolerance of the transgenic protein, thus avoiding the dominant problem in haemophilia treatment, the formation of inhibitory antibodies.
  
  
  METHODS
  Adenovirus serotype 5-derived or AAV serotype 2-derived vectors carrying human clotting factor IX (hfIX) cDNA or a reporter gene were administered intramuscularly, intraperitoneally or intravascularly to late-gestation mouse fetuses. Both vector types were evaluated with respect to the kinetics of hfIX delivery to the systemic circulation and possible immune responses against the vector or the transgene product.
  
  
  RESULTS
  Mice treated in utero by intramuscular injection of an adenoviral vector carrying hfIX cDNA exhibited high-level gene expression at birth and therapeutic--albeit continuously decreasing--plasma concentrations of hfIX over the entire 6 months of the study. Adenoviral vector spread to multiple organs was detected by polymerase chain reaction (PCR). Intramuscular, intraperitoneal or intravascular application of AAV vectors carrying hfIX cDNA led to much lower plasma concentrations of hfIX shortly after birth, which appeared to decline during the first month of life but stabilized in some of the mice at detectable levels. No signs of immune responses were found, either against the different viral vectors or against hfIX.
  
  
  CONCLUSIONS
  This study demonstrates for the first time that sustained systemic delivery of a therapeutic protein can be achieved by prenatal gene transfer. It thus shows the feasibility of gene therapy in utero and provides a basis for considering this concept as a preventive therapeutic strategy for haemophilia and perhaps also for other plasma protein deficiencies.
authors.affiliation: Children's Hospital, University of Erlangen-Nuernberg, Germany. holm.schneider@kinder.imed.uni-erlangen.de
authors.forename: Holm
authors.initials: H
authors.lastname: Schneider
authors.forename: Christiane
authors.initials: C
authors.lastname: Mühle
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: Douar
authors.forename: Simon
authors.initials: S
authors.lastname: Waddington
authors.forename: Qiu-Jie
authors.initials: QJ
authors.lastname: Jiang
authors.forename: Klaus
authors.initials: K
authors.lastname: von der Mark
authors.forename: Charles
authors.initials: C
authors.lastname: Coutelle
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rascher
mesh_terms: D000256:Adenoviridae; D000818:Animals; D000906:Antibodies; D018076:DNA, Complementary / Q000008:administration & dosage / Q000235:genetics; D000229:Dependovirus; D005164:Factor IX / Q000235:genetics* / Q000627:therapeutic use*; D005260:Female; D005333:Fetus; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D005822:Genetic Vectors; D002836:Hemophilia B / Q000235:genetics / Q000628:therapy*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009132:Muscles; D011247:Pregnancy; D011295:Prenatal Care
chemical_list: D000906:Antibodies; D018076:DNA, Complementary; D005164:Factor IX