ADENOVIRAL VECTOR-DIRECTED EXPRESSION OF NEUROTROPHIN-3 IN RAT DORSAL-ROOT GANGLION EXPLANTS RESULTS IN A ROBUST NEURITE OUTGROWTH RESPONSE

The neurotrophins are a family of proteins that promote neuronal survi val and neurite outgrowth during development and can also enhance the regeneration of injured adult neurons, The local and continuous delive ry of these proteins at the site of injury is problematic, since this requires repeated intraparenchymal injections or the use of invasive c anula-micropump devices, In the present study we report the generation and characterization of an adenoviral vector for a member of the neur otrophins, neurotrophin-3 (Ad-NT-3). Using Ad-NT-3, we examined the ex pression and biological activity of NT-3 in dorsal root ganglia (DRG) explant cultures, Gene transfer with Ad-NT-3 results in the synthesis of genuine NT-3 and in a dosage-dependent neurite outgrowth response i n DRG explants. Transduction of DRG explants with a viral vector dosag e of 5 x 10(5) to 5 x 10(6) plaque-forming units induced the formation of a dense halo of neurites comparable to outgrowth observed followin g the addition of 100 ng/mL exogenous NT-3. In addition, a single infe ction with Ad-NT-3 produced biologically active NT-3 for at least 20 d ays in culture, as evidenced by continued neurite extension, This indi cates that adenoviral vector-mediated expression of NT-3 results in hi gh-level production of biologically active NT-3 and could therefore he used as a strategy to promote the regeneration of injured peripheral and central nerve projections. (C) 1997 John Wiley & Sons, Inc.