title: Gene therapy targeting oligodendrocytes provides therapeutic benefit in a leukodystrophy model.
abstract: Pelizaeus-Merzbacher-like disease or hypomyelinating leukodystrophy-2 is an autosomal recessively inherited leukodystrophy with childhood onset resulting from mutations in the gene encoding the gap junction protein connexin 47 (Cx47, encoded by GJC2). Cx47 is expressed specifically in oligodendrocytes and is crucial for gap junctional communication throughout the central nervous system. Previous studies confirmed that a cell autonomous loss-of-function mechanism underlies hypomyelinating leukodystrophy-2 and that transgenic oligodendrocyte-specific expression of another connexin, Cx32 (GJB1), can restore gap junctions in oligodendrocytes to achieve correction of the pathology in a disease model. To develop an oligodendrocyte-targeted gene therapy, we cloned the GJC2/Cx47 gene under the myelin basic protein promoter and used an adeno-associated viral vector (AAV.MBP.Cx47myc) to deliver the gene to postnatal Day 10 mice via a single intracerebral injection in the internal capsule area. Lasting Cx47 expression specifically in oligodendrocytes was detected in Cx47 single knockout and Cx32/Cx47 double knockout mice up to 12 weeks post-injection, including the corpus callosum and the internal capsule but also in more distant areas of the cerebrum and in the spinal cord. Application of this oligodendrocyte-targeted somatic gene therapy at postnatal Day 10 in groups of double knockout mice, a well characterized model of hypomyelinating leukodystrophy-2, resulted in significant improvement in motor performance and coordination at 1 month of age in treated compared to mock-treated mice, as well as prolonged survival. Furthermore, immunofluorescence and morphological analysis revealed improvement in demyelination, oligodendrocyte apoptosis, inflammation, and astrogliosis, all typical features of this leukodystrophy model in both brain and spinal cord. Functional dye transfer analysis confirmed the re-establishment of oligodendrocyte gap junctional connectivity in treated as opposed to untreated mice. These results provide a significant advance in the development of oligodendrocyte-cell specific gene therapy. Adeno-associated viral vectors can be used to target therapeutic expression of a myelin gene to oligodendrocytes. We show evidence for the first somatic gene therapy approach to treat hypomyelinating leukodystrophy-2 preclinically, providing a potential treatment for this and similar forms of leukodystrophies.
authors.affiliation: Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus.
authors.forename: Elena
authors.initials: E
authors.lastname: Georgiou
authors.affiliation: Department of Zoology, University of Crete, Heraklion, Greece.
authors.forename: Kyriaki
authors.initials: K
authors.lastname: Sidiropoulou
authors.affiliation: Department of Molecular Virology, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus.
authors.forename: Jan
authors.initials: J
authors.lastname: Richter
authors.affiliation: Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus.
authors.forename: Christos
authors.initials: C
authors.lastname: Papaneophytou
authors.affiliation: Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus.
authors.forename: Irene
authors.initials: I
authors.lastname: Sargiannidou
authors.affiliation: Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus.
authors.forename: Alexia
authors.initials: A
authors.lastname: Kagiava
authors.affiliation: Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia.
authors.forename: Georg
authors.initials: G
authors.lastname: von Jonquieres
authors.affiliation: Department of Molecular Virology, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus.
authors.forename: Christina
authors.initials: C
authors.lastname: Christodoulou
authors.affiliation: Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia.
authors.forename: Matthias
authors.initials: M
authors.lastname: Klugmann
authors.affiliation: Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus.|Neurology Clinics, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus.
authors.forename: Kleopas A
authors.initials: KA
authors.lastname: Kleopa
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015703:Antigens, CD / Q000378:metabolism; D017209:Apoptosis / Q000235:genetics; D017630:Connexins / Q000172:deficiency / Q000235:genetics; D000229:Dependovirus / Q000235:genetics; D004195:Disease Models, Animal; D005786:Gene Expression Regulation / Q000235:genetics*; D015316:Genetic Therapy / Q000379:methods*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D056784:Leukoencephalopathies / Q000235:genetics / Q000628:therapy; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009069:Movement Disorders / Q000209:etiology; D004676:Myelin Basic Protein / Q000235:genetics / Q000378:metabolism; D009186:Myelin Sheath / Q000378:metabolism / Q000473:pathology; D009836:Oligodendroglia / Q000378:metabolism*; D011597:Psychomotor Performance / Q000502:physiology; D000097002:Gap Junction beta-1 Protein
chemical_list: D015703:Antigens, CD; D017630:Connexins; D049452:Green Fluorescent Proteins; D004676:Myelin Basic Protein; D000097002:Gap Junction beta-1 Protein; C427305:connexin 47; C485184:enhanced green fluorescent protein
keywords: AAV&comma; gene therapy; connexin; gap junctions; leukodystrophy; myelin basic protein promoter