Non-invasive intrathecal AAV-10 vector-mediated administration of Neurotrophin-3 (AAV10-NT3-gfp) at chronic stage of contusion spinal cord injury (SCI) in rats
Abstract: Insufficient neurotrophin (NT-3) support is one of the major factors restricting synaptic transmission and plasticity in the damaged spinal cord. From our previous studies: although administration of NT-3 alone immediately after SCI has not shown significant improvements, NT-3 is an essential component of combination treatment. In an attempt to design an approach for prolonged delivery of NT-3, we have successfully created the new AAV10-NT3gfp construct. Our previous experiments revealed an excellent transduction of neurons and glial cells in damaged spinal cord, after two weeks following thoracic contusion and intraspinal injections of AAV10-NT3-gfp, immediately after contusion injury. In this study, we sought to examine a more clinically relevant approach for AAV vector administration, i.e. intrathecal administration of AAV vector at chronic stage of injury. Adult rats received moderate contusion (150 kdyn) injury at thoracic T10 level using an IH impactor device. Locomotor performance was evaluated pre-injury, 2 days after SCI and then weekly for 6 weeks (automated Catwalk gait; Irregular Grid and Narrowing Beam tests). After 6 weeks post-injury, when the scores of all behavioral tests and gait analyses plateaued, rats were re-anesthetized and AAV10-NT3-gfp was administered intrathecally, using a 32 Gage Teflon catheter that was inserted through a small hole in the dura (made by needle) one segment caudal to injury, with the tip of the catheter positioned just caudal to the injury. Consistent with the results of previous experiments that examined acute effects of NT-3 alone, we found that delayed administration of AAV10-NT3-gfp alone has not induced improvements of locomotor function following chronic contusion SCI.
After completion of behavioral testing, spinal horizontal sections were prepared and unamplified GFP signal is under examination. So far, we have observed the GFP signal in axons and glial cells close to injury epicenter; although this signal was lower as compared to intraspinal injections. Quantitative analyses of the transduction efficacy of neurons and glia are still ongoing. Although these experiments were important to examine effects of AAV10-NT3-gfp alone and to ensure transduction efficacy following intrathecal administration of AAV10-based vector at the chronic stage of SCI, further experiments will be conducted to examine effects of intrathecal administration of AAV10-NT3 combined with other treatments, i.e. AAV10-NG2antibody, following chronic SCI.
Society for Neuroscience Chicago 2015 Neurodegeneration Drug Discovery: AD, PD, and Gene Therapy
Support: Craig H. Neilsen Foundation Merit Review Funding from the Department of Veterans Affairs
Department of Defense New York State Spinal Cord Injury Research Board
Authors: *V. L. ARVANIAN1,2, H. PETROSYAN1, V. ALESSI1, J. M. LEVINE2; 1VA Med. Ctr., Northport, NY; 2Neurobio. and Behavior, Stony Brook Univ., Stony Brook, NY
Disclosures: V.L. Arvanian: None. H. Petrosyan: None. V. Alessi: None. J.M. Levine: None.