title: Hematopoietic-specific lentiviral vectors circumvent cellular toxicity due to ectopic expression of Wiskott-Aldrich syndrome protein.
abstract: Efficient and safe gene modification of hematopoietic stem cells is a requirement for gene therapy of primary immunodeficiencies such as Wiskott-Aldrich syndrome. However, deregulated expression or ectopic expression in the progeny of transduced nonhematopoietic progenitor cells may lead to unwanted toxicity. We therefore analyzed the effect of ectopic expression of Wiskott-Aldrich syndrome protein (WASp) and the potential benefits of hematopoietic-specific lentiviral vectors (driven by the WAS proximal promoter). Overexpression of WASp by constitutive lentiviral vectors is highly toxic in nonhematopoietic cells because it causes dramatic changes in actin localization and polymerization that result in decreased cell viability, as evidenced by a significant growth disadvantage of WASp-overexpressing nonhematopoietic cells and increased cell death. These toxic effects do not affect cells of hematopoietic origin because, remarkably, we found that WASp cannot be readily overexpressed in T cells, even after multiple vector integrations per cell. The adverse cellular effects found after transduction of nonhematopoietic cells with constitutive lentiviral vectors are overcome by the use of transcriptionally targeted lentiviral vectors expressing WASp, which, at the same time, are efficient tools for gene therapy of WAS as demonstrated by their ability to reconstitute cellular defects from WASp-deficient mouse and human cells. We therefore postulate that transcriptionally regulated lentiviral vectors represent a safer and efficient alternative for the development of clinical protocols of WAS gene therapy.
authors.affiliation: Immunology and Cell Biology Department, Institute of Parasitology and Biomedicine López Neyra, CSIC, Parque Tecnológico Ciencias de la Salud, 18100 Granada, Spain.
authors.forename: Miguel G
authors.initials: MG
authors.lastname: Toscano
authors.forename: Cecilia
authors.initials: C
authors.lastname: Frecha
authors.forename: Karim
authors.initials: K
authors.lastname: Benabdellah
authors.forename: Marien
authors.initials: M
authors.lastname: Cobo
authors.forename: Mike
authors.initials: M
authors.lastname: Blundell
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Thrasher
authors.forename: Enrique
authors.initials: E
authors.lastname: García-Olivares
authors.forename: Ignacio J
authors.initials: IJ
authors.lastname: Molina
authors.forename: Francisco
authors.initials: F
authors.lastname: Martin
mesh_terms: D000818:Animals; D016923:Cell Death; D002460:Cell Line; D049109:Cell Proliferation; D003599:Cytoskeleton / Q000378:metabolism; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006413:Hematopoietic System / Q000166:cytology*; D006801:Humans; D016086:Lentivirus / Q000235:genetics*; D051379:Mice; D009928:Organ Specificity; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013601:T-Lymphocytes / Q000648:ultrastructure; D014158:Transcription, Genetic; D014923:Wiskott-Aldrich Syndrome / Q000235:genetics / Q000473:pathology / Q000628:therapy; D051316:Wiskott-Aldrich Syndrome Protein / Q000235:genetics*
chemical_list: D011993:Recombinant Fusion Proteins; D051316:Wiskott-Aldrich Syndrome Protein; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins