Intraneural colchicine inhibition of adenoviral and adeno-associated viral vector remote spinal cord gene delivery.

OBJECTIVE: The mechanism of remote viral gene delivery to the spinal cord is unknown. The present experiment demonstrates that intraneural injection of colchicine is capable of inhibiting remote delivery of both adenoviral and adeno-associated viral (AAV) vectors, implicating axonal transport in this process. METHODS: The right sciatic nerves of adult Sprague-Dawley rats were injected with phosphate-buffered saline (PBS) (n = 5) or 10 (n = 7) or 100 (n = 4) μg colchicine. Two days later, the nerves of all animals were initially injected with 1.2 × 10 7 plaque-forming units of of Ad5RSVntLac-Z. Two separate groups were injected concurrently with vector and PBS (n 5) or 10 μg colchicine (n = 5). In a second experiment, the right sciatic nerves of CD1 mice were preinjected with PBS (n = 6) or 10 μg colchicine (n = 5). Two days later, the nerves were injected with rAAVCAG-EGFPwpre (an adeno-associated vector carrying the green fluorescent protein gene). In both experiments, sciatic nerves and spinal cords were removed and analyzed for gene expression. RESULTS: Sciatic nerve vector injection resulted in expression in both the nerve injection site and neuronal cell bodies located predominantly in the silateral ventral horn. Analysis of variance revealed a significant treatment effect for 10 and 100 μg intraneural colchicine with inhibition of remote auenoviral delivery at 10 μg and blockade of remote delivery at 100 μg (P < 0.001). Colchicine injection concurrent with and before vector injection had similar inhibitory effects. Two-way analysis of variance revealed significant colchicine inhibition of remote delivery in both adenovirus- and AAV-injected animals (P < 0.003) but no dose-by-vector interaction, suggesting that both vectors are equally inhibited by colchicine. CONCLUSION: Colchicine inhibits remote spinal cord delivery of adeno-associated and adenoviral vectors in a dose-dependent manner, suggesting that remote delivery is dependent on retrograde axonal transport.