Adeno-associated viral vector-mediated neurotrophin gene transfer in the injured adult rat spinal cord improves hind-limb function

• Published in: Neuroscience 2003-04, Vol.118 (1), p.271-281
• Main Authors: BLITS, B, OUDEGA, M, BOER, G. J, BUNGE, M. Bartlett, VERHAAGEN, J
• Format: Article
• Language: English
• Subjects: Adeno-associated virus; Adenoviridae - genetics; Animals; Biological and medical sciences; Brain Tissue Transplantation; Brain-Derived Neurotrophic Factor - genetics; Brain-Derived Neurotrophic Factor - therapeutic use; Development. Senescence. Regeneration. Transplantation; Female; Fluorescent Dyes; Fundamental and applied biological sciences. Psychology; Gene Transfer Techniques - trends; Genetic Vectors - therapeutic use; Graft Survival - genetics; Growth Cones - metabolism; Growth Cones - ultrastructure; Hindlimb - innervation; Hindlimb - physiopathology; Nerve Growth Factors - genetics; Nerve Growth Factors - therapeutic use; Nerve Regeneration - genetics; Neural Pathways - cytology; Neural Pathways - growth & development; Neural Pathways - surgery; Neurotrophin 3 - genetics; Neurotrophin 3 - therapeutic use; Rats; Rats, Inbred F344; Recombinant Fusion Proteins; Recovery of Function - genetics; Schwann Cells - cytology; Schwann Cells - transplantation; Spinal Cord - cytology; Spinal Cord - growth & development; Spinal Cord - surgery; Spinal Cord Injuries - genetics; Spinal Cord Injuries - therapy; Treatment Outcome; Vertebrates: nervous system and sense organs
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/s0306-4522(02)00970-3

To foster axonal growth from a Schwann cell bridge into the caudal spinal cord, spinal cells caudal to the implant were transduced with adeno-associated viral (AAV) vectors encoding for brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (AAV-NT-3). Control rats received AAV vectors encoding for green fluorescent protein or saline. AAV-BDNF- and AAV-NT-3-transduced 293 human kidney cells produced and secreted BDNF or NT-3, respectively, in vitro. The secreted neurotrophins were biologically active; they both promoted outgrowth of sensory neurites in vitro. In vivo, transgene expression was observed predominantly in neurons for at least 16 weeks after injection. Compared with controls, a modest though significant improvement in hind-limb function was found in rats that received AAV-BDNF and AAV-NT-3. Retrograde tracing demonstrated that twice as many neurons with processes extending toward the Schwann cell graft were present in the second lumbar cord segment of AAV-BDNF- and AAV-NT-3-injected animals compared with controls. We found no evidence, however, for growth of regenerated axons from the Schwann cell implant into the caudal cord. Our results suggest that AAV vector-mediated overexpression of BDNF and NT-3 in the cord caudal to a Schwann cell bridge modified the local lumbar axonal circuitry, which was beneficial for locomotor function.