(PNS) injection of the adenoviral and adeno-associated viral vectors (rAAV) results in segmental delivery of recombinant genes to spinal cord sensory and motor neurons

a. Specific Aims Advancements in both neuroscience and engineering have provided neurosurgery with new paradigms for the restoration of neural function. In particular, the dual emergence of accurate stereotaxis and deep brain stimulation (DBS) have generated a revolution in the application of targeted neuromodulation. DBS allows for focused reversible inhibition of neural function, while advanced generation computers have made precise targeting and safe implantation through stereotaxis possible. Targeted neuromodulation is currently applied to a variety of movement disorders (1), but has shown the potential to provide novel treatments for epilepsy, eating disorders, obsessive compulsive disease, and pain (Appendix C). Nonetheless, because DBS depends on the focused delivery of electric current, it is incapable of pharmacological specificity and requires electronic neural prostheses that carry a significant complication rate. Viral gene therapy has several advantages over DBS for the treatment of central nervous system (CNS) diseases. Rather than delivering electric current, viral vectors can alter synaptic function with molecular specificity. For example, delivery of the preproenkephalin gene to sensory neurons inhibits pain (2). Further, the genes for dopamine producing enzymes can correct models of Parkinson's disease (3). Viral vectors can also be constructed to deliver transgenes capable of promoting neuronal survival. For example, viral-mediated induction of glial derived neurotrophic factor and nerve growth factor are protective in models of Parkinson's (4) and Alzheimer's disease, respectively (5). In addition to molecular specificity, vectors may be delivery to specific neuronal populations. Our recent data suggest that peripheral nervous system (PNS) injection of the adenoviral and adeno-associated viral vectors (rAAV) results in segmental delivery of recombinant genes to spinal cord sensory and motor neurons (6-8). Further, vector tropism can be modified to alter cell type tropism, creating the potential for system specific neuronal gene delivery (9). The experiments outlined in this proposal attempt to develop a vector capable of both neural tropism and neuromodulation. To test these concepts, we propose to develop a recombinant adeno-associated virus (rAAV) capable of synaptic inhibition and motor neuron tropism. We have chosen the spinal reflex arc as a simple mammalian functional system amenable to neuromodulation. In addition, the functional disorder, spasticity, provides a target for the study of applied neuromodulation. The simplicity of the spinal reflex arc provides the potential for a better understanding of the mechanisms underlying gene-based neuromodulation. We hypothesize that an rAAV vector capable of specific motor neuron inhibition will have therapeutic efficacy in animal models …