title: Hematopoietic gene therapy restores thymidine phosphorylase activity in a cell culture and a murine model of MNGIE.
abstract: Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder caused by mutations in the TYMP gene, which encodes thymidine phosphorylase (TP). TP dysfunction results in systemic thymidine (dThd) and deoxyuridine (dUrd) overload, which selectively impair mitochondrial DNA replication. Allogeneic hematopoietic transplantation has been used to treat MNGIE patients; however, this approach has serious adverse effects, including the toxicity of myeloablative conditioning, graft rejection and graft-versus-host disease. With the aim of testing the feasibility of gene therapy for MNGIE, we transduced TP-deficient B-lymphoblastoid cells from two MNGIE patients, with lentiviral vectors carrying a functional copy of the human TYMP DNA coding sequence. This restored TP activity in the cells, which reduced the excretion of dThd and dUrd and their concentrations when added in excess. Additionally, lentiviral-mediated hematopoietic gene therapy was used in partially myeloablated double Tymp/Upp1 knockout mice. In spite of the relatively low levels of molecular chimerism achieved, high levels of TP activity were observed in the peripheral blood of the transplanted mice, with a concomitant reduction of nucleoside concentrations. Our results suggest that hematopoietic gene therapy could be an alternative treatment for this devastating disorder in the future.
authors: Laboratori of Neuromuscular and Mitochondrial Disorders, Institut de Recerca Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
authors: J
authors: J
authors: Torres-Torronteras
authors: A
authors: A
authors: Gómez
authors: H
authors: H
authors: Eixarch
authors: L
authors: L
authors: Palenzuela
authors: G
authors: G
authors: Pizzorno
authors: M
authors: M
authors: Hirano
authors: A L
authors: AL
authors: Andreu
authors: J
authors: J
authors: Barquinero
authors: R
authors: R
authors: Martí
mesh_terms: D000818:Animals; D001402:B-Lymphocytes; D018929:Cell Culture Techniques; D002460:Cell Line; D005240:Feasibility Studies; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D006801:Humans; D016086:Lentivirus / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D017237:Mitochondrial Encephalomyopathies / Q000628:therapy*; D013939:Thymidine Phosphorylase / Q000235:genetics* / Q000378:metabolism; D014161:Transduction, Genetic
chemical_list: D013939:Thymidine Phosphorylase