title: Neurite outgrowth can be modulated in vitro using a tetracycline-repressible gene therapy vector expressing human nerve growth factor.
abstract: The delivery of neurotrophic factors to the adult nervous system has potential applications for the treatment of neurodegenerative diseases and trauma. In vivo and ex vivo gene therapy offer a means of delivering growth factors and other therapeutic substances to the central nervous system (CNS) in an intraparenchymal, accurately targeted, and regionally restricted manner. Ideally, gene therapy delivery systems should also be regulatable, allowing exogenous control of amount of gene product delivery. In the present experiment, a tetracycline-regulatable gene expression system was generated to determine whether controllable release of nerve growth factor (NGF) and green fluorescent protein (GFP) from primary rat fibroblasts could modulate biological responses (neurite outgrowth) in vitro. Using a tetracycline-repressible construct, it was found that NGF mRNA, NGF protein, and NGF-induced neurite outgrowth could be tightly regulated within a 24 hour period, and in a dose-dependent fashion, by exposure to the tetracycline analog doxycycline. Similarly, levels of green fluorescence could be regulated in GFP-transfected cells. These findings in a neurobiological system lay the framework for future studies using regulated neurotrophin delivery in in vivo models of neurodegenerative diseases and CNS injury.
authors.affiliation: Department of Neurosciences-0626, University of California, San Diego, La Jolla, California 92093-0626, USA.
authors.forename: A
authors.initials: A
authors.lastname: Blesch
authors.forename: H S
authors.initials: HS
authors.lastname: Uy
authors.forename: N
authors.initials: N
authors.lastname: Diergardt
authors.forename: M H
authors.initials: MH
authors.lastname: Tuszynski
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002478:Cells, Cultured; D015870:Gene Expression / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000187:drug effects / Q000378:metabolism*; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics; D020932:Nerve Growth Factor / Q000235:genetics*; D016501:Neurites / Q000502:physiology*; D051381:Rats; D011916:Rats, Inbred F344; D013752:Tetracycline / Q000494:pharmacology*; D014162:Transfection
chemical_list: D000900:Anti-Bacterial Agents; D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D020932:Nerve Growth Factor; D013752:Tetracycline