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The assessment of adeno‐associated vectors as potential intrinsic treatments for brainstem axon regeneration
Author(s) -
Williams Ryan R.,
Pearse Damien D.,
Tresco Patrick A.,
Bunge Mary Bartlett
Publication year - 2012
Publication title -
the journal of gene medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.689
H-Index - 91
eISSN - 1521-2254
pISSN - 1099-498X
DOI - 10.1002/jgm.1628
Subject(s) - axon , brainstem , adeno associated virus , green fluorescent protein , regeneration (biology) , spinal cord , biology , wallerian degeneration , neuroscience , microbiology and biotechnology , spinal cord injury , transgene , anatomy , pathology , medicine , vector (molecular biology) , recombinant dna , biochemistry , gene
Background Adeno‐associated virus (AAV) vector‐mediated transgene expression is a promising therapeutic to change the intrinsic state of neurons and promote repair after central nervous system injury. Given that numerous transgenes have been identified as potential candidates, the present study demonstrates how to determine whether their expression by AAV has a direct intrinsic effect on axon regeneration. Methods Serotype 2 AAV‐enhanced green fluorescent protein (EGFP) was stereotaxically injected into the brainstem of adult rats, followed by a complete transection of the thoracic spinal cord and Schwann cell (SC) bridge implantation. Results The expression of EGFP in brainstem neurons labeled numerous axons in the thoracic spinal cord and that regenerated into the SC bridge. The number of EGFP‐labeled axons rostral to the bridge directly correlated with the number of EGFP‐labeled axons that regenerated into the bridge. Animals with a greater number of EGFP‐labeled axons rostral to the bridge exhibited an increased percentage of those axons found near the distal end of the bridge compared to animals with a lesser number. This suggested that EGFP may accumulate distally in the axon with time, enabling easier visualization. By labeling brainstem axons with EGFP before injury, numerous axon remnants undergoing Wallerian degeneration may be identified distal to the complete transection up to 6 weeks after injury. Conclusions Serotype 2 AAV‐EGFP enabled easy visualization of brainstem axon regeneration. Rigorous models of axonal injury (i.e. complete transection and cell implantation) should be used in combination with AAV‐EGFP to directly assess AAV‐mediated expression of therapeutic transgenes as intrinsic treatments to improve axonal regeneration. Copyright © 2012 John Wiley & Sons, Ltd.