title: Expression of biologically active human insulin-like growth factor-I following intramuscular injection of a formulated plasmid in rats.
abstract: Recent evidence has shown that insulin-like growth factor-I (IGF-I) plays an important role in the development, maintenance, and regeneration of peripheral nerves and skeletal muscle. IGF-I offers the potential to treat neuromuscular diseases in humans. We have developed a nonviral gene therapy method to express and produce localized and sustained therapeutic levels of IGF-I within target muscles by intramuscular injection of formulated plasmids. The purpose of the present study was to demonstrate that intramuscular injection of a plasmid encoding human IGF-I (hIGF-I) and engineered to restrict expression to skeletal muscle produces sustained local concentrations of biologically active hIGF-I. Normal rats received a single intramuscular injection of plasmids formulated as a complex with polyvinylpyrrolidone (PVP). Results show that hIGF-I mRNA and hIGF-I protein were detectable in the injected muscles for the duration of the study (28 days), whereas the hIGF-I protein was not detected in blood. Biological activity of hIGF-I was determined by immunodetection of a nerve-specific growth-associated protein, GAP-43, an indicator of motor neuron sprouting. Placement of human growth hormone (hGH) 3' untranslated region enhanced GAP-43 staining, probably due to improved secretion of hIGF-I. Enhanced immunoreactivity of GAP-43 was observed in muscles injected with the formulated hIGF-I plasmid when compared to controls. These results demonstrate that intramuscular injection of hIGF-I plasmid formulated as a complex with PVP produces a localized and sustained level of biologically active hIGF-I.
authors.affiliation: GeneMedicine, Inc. The Woodlands, TX 77381-4248, USA.
authors.forename: H
authors.initials: H
authors.lastname: Alila
authors.forename: M
authors.initials: M
authors.lastname: Coleman
authors.forename: H
authors.initials: H
authors.lastname: Nitta
authors.forename: M
authors.initials: M
authors.lastname: French
authors.forename: K
authors.initials: K
authors.lastname: Anwer
authors.forename: Q
authors.initials: Q
authors.lastname: Liu
authors.forename: T
authors.initials: T
authors.lastname: Meyer
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: R
authors.initials: R
authors.lastname: Mumper
authors.forename: D
authors.initials: D
authors.lastname: Oubari
authors.forename: S
authors.initials: S
authors.lastname: Long
authors.forename: J
authors.initials: J
authors.lastname: Nordstrom
authors.forename: A
authors.initials: A
authors.lastname: Rolland
mesh_terms: D000818:Animals; D002460:Cell Line; D015870:Gene Expression; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D006801:Humans; D007273:Injections, Intramuscular; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis / Q000235:genetics*; D008297:Male; D051379:Mice; D010957:Plasmids / Q000008:administration & dosage; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D007334:Insulin-Like Growth Factor I