The transfer of novel genes (see GENE) that encode PROTEINS—such as NEUROTRANSMITTERS, RECEPTOR SUB-UNITS, ENZYMES, or GROWTH FACTORS—into the nervous system. Three main methodologies are widespread. (1) Ex vivo gene transfer: The gene is introduced into cells by a variety of techniques including incorporating the gene into a RETROVIRUS which is then used to infect dividing cells in TISSUE CULTURE. Infected cells can be tested for their inclusion of the gene and for their ability to synthesize and release the gene product. The infected cells are then transferred by TRANSPLANTATION into the host brain.
(2) In vivo gene transfer: Most viruses only infect dividing cells and so cannot be used to transfer genes into adult neurons. However, various types of virus (for example, adenovirus, adeno-associated virus, and herpes simplex-1) can infect post-mitotic cells (see CELL DIVISION) and so these can be used as vectors to transfer genes into the mature brain by direct inoculation (see VIRAL VECTOR). (3) TRANSGENIC animals: The gene is introduced into the germ line of embryos, and lines of animals carrying the gene are maintained by selective breeding.
Reference
Gage F.H., Kawaja M.D. & Fisher L.J. (1991) Genetically modified cells: applications for intracerebral grafting. Trends in Neuroscience 14:328–333.
STEPHEN B. DUNNETT
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