1062. Intracerebellar Injection of AAV-IGF-1 Improves Motor Function and Extends Survival in a Mouse Model of Amyotrophic Lateral Sclerosis

Abstract

Amytrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that is characterized by a selective loss of motor neurons in the motor cortex, brain stem and spinal cord. The etiology of motor neuron degeneration remains largely unknown. Although chronic delivery of therapeutic agents to the central nervous system has proven to be difficult, recent studies have demonstrated that intramuscular delivery of adeno-associated viral vectors encoding insulin growth factor 1 (AAV-IGF-1) slowed disease progression and extended survival in SOD1G93A mice. The efficacy of viral mediated expression of IGF-1 was mediated in part by the ability of the viral vector to undergo retrograde transport from muscle to motor neurons. Previously we demonstrated that targeting the deep cerebellar nuclei (DCN) of the cerebellum with viral vectors capable of axonal transport resulted in detection of transgene protein in both the brain stem and spinal cord (Dodge et al. 2005, PNAS 102:17822-17827). In this experiment we evaluated the efficacy of bilateral delivery of AAV1|[ndash]|IGF-1 and AAV2-IGF-1 to the DCN in 90 day old SOD1G93A mice. Starting at 80 days of age (and every 10 days thereafter), SOD1G93A mice underwent behavioral testing (rotarod, hindlimb and forelimb grip strength) to assess motor function. At 90 days of age (i.e., time point at which SOD1 mice exhibit overt disease symptoms of ALS) mice received stereotaxic bilateral injections of AAV1-IGF-I (n=26), AAV2-IGF-I (n=27), AAV1-GFP (n=26) or AAV2-GFP (n=25) aimed at the deep cerebellar nuclei (DCN) of the cerebellum. We found that bilateral delivery of AAV- IGF-1 treatment (regardless of serotype) to the DCN significantly promoted motor neuron survival, improved motor performance in both rotarod and grip strength behavioral tests and significantly extended lifespan (i.e., 12 day extension for AAV1-IGF-1 and 14 day extension for AAV2-IGF-1). Treatment with AAV-GFP had no effect on any of the parameters mentioned above. Our results indicate that direct administration of AAV-IGF-1 into the DCN modifies disease progression in a mouse model of ALS and that targeting the DCN with AAV vectors is an effective approach for delivering therapeutic transgenes to both the brain and spinal cord for the treatment of ALS.