Degradation of chondroitin sulfate proteoglycans potentiates transplant-mediated axonal remodeling and functional recovery after spinal cord injury in adult rats.
Transplantation of growth-permissive cells or tissues was used to bridge a lesion cavity and induce axonal growth in experimental spinal cord injury (SCI). Axonal interactions between host and transplant may be affected by upregulation of inhibitory chondroitin sulfate proteoglycans (CSPGs) following various transplantation strategies. The extent of axonal growth and functional recovery after transplantation of embryonic spinal cord tissue decreases in adult compared to neonatal host. We hypothesized that CSPGs contribute to the decrease in the extent to which transplant supports axonal remodeling and functional recovery. Expression of CSPGs increased after overhemisection SCI in adult rats but not in neonates. Embryonic spinal cord transplant was surrounded by CSPGs deposited in host cord, and the interface between host and transplant seemed to contain a large amount of CSPGs. Intrathecally delivered chondroitinase ABC (C'ase) improved recovery of distal forelimb usage and skilled motor behavior after C4 overhemisection injury and transplantation in adults. This behavioral recovery was accompanied by an increased amount of raphespinal axons growing into the transplant, and raphespinal innervation to the cervical motor region was promoted by C'ase plus transplant. Moreover, C'ase increased the number of transplanted neurons that grew axons to the host cervical enlargement, suggesting that degradation of CSPGs supports remodeling not only of host axons but also axons from transplanted neurons. Our results suggest that CSPGs constitute an inhibitory barrier to prevent axonal interactions between host and transplant in adults, and degradation of the inhibitory barrier can potentiate transplant-mediated axonal remodeling and functional recovery after SCI.
Kim
Byung G
BG
Department of Neuroscience, Georgetown University Medical Center, Washington, DC 20007, USA.
Dai
Hai-Ning
HN
Lynskey
James V
JV
McAtee
Marietta
M
Bregman
Barbara S
BS
D000818:Animals; D000831:Animals, Newborn; D001369:Axons / Q000187:drug effects / Q000502:physiology*; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D001710:Biotin / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D002452:Cell Count / Q000379:methods; D017690:Cell Transplantation; D019765:Chondroitin ABC Lyase / Q000008:administration & dosage; D011508:Chondroitin Sulfate Proteoglycans / Q000378:metabolism*; D003911:Dextrans / Q000493:pharmacokinetics; D003952:Diagnostic Imaging / Q000379:methods; D004195:Disease Models, Animal; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D007150:Immunohistochemistry / Q000379:methods; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000378:metabolism; D013119:Spinal Cord Injuries / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery; D013997:Time Factors
D011508:Chondroitin Sulfate Proteoglycans; D003911:Dextrans; C076397:biotinylated dextran amine; D012701:Serotonin; D001710:Biotin; D010751:Phosphopyruvate Hydratase; D019765:Chondroitin ABC Lyase