Regeneration of lesioned corticospinal tract fibers in the adult rat induced by a recombinant, humanized IN-1 antibody fragment.
Axons in the CNS of higher vertebrates generally fail to regenerate after injury. This lack of regeneration is crucially influenced by neurite growth inhibitory protein constituents of CNS myelin. We have shown previously that a monoclonal antibody (mAb IN-1) capable of binding and neutralizing Nogo-A, a myelin-associated inhibitor of neurite growth, can induce long-distance axonal regeneration and increased structural plasticity with improved functional recovery in rat models of CNS injury. In this paper we demonstrate that a partially humanized, recombinant Fab fragment (rIN-1 Fab) derived from the original mAb IN-1, was able to promote long-distance regeneration of injured axons in the spinal cord of adult rats. When infused into a spinal cord injury site, regrowth of corticospinal fibers in 11 of 18 animals was observed after a survival time of 2 weeks. Regenerating fibers grew for >9 mm beyond the lesion site and arborized profusely in the distal cord. Regenerated fibers formed terminal arbors with varicosities in the spinal cord gray matter, strongly resembling synaptic points of contact to neurons in the spinal cord distal to the lesion. In animals that had received a bovine serum albumin solution or a recombinant IN-1 fragment that had been mutated in the antigen binding site (mutIN-1 Fab), no significant growth beyond normal lesion-induced sprouting was observed. Neutralization of endogenous nerve growth inhibitors represents a novel use of recombinant antibody technology with potential therapeutic applications after traumatic CNS lesions.
Brösamle
C
C
Brain Research Institute, Department of Neuromorphology, University of Zurich, Switzerland. broesam@hifo.unizh.ch.
Huber
A B
AB
Fiedler
M
M
Skerra
A
A
Schwab
M E
ME
D016475:3T3 Cells; D000818:Animals; D001681:Biological Assay; D002478:Cells, Cultured; D002642:Chick Embryo; D004195:Disease Models, Animal; D005260:Female; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism; D006131:Growth Inhibitors / Q000037:antagonists & inhibitors; D006801:Humans; D007128:Immunoglobulin Fragments / Q000008:administration & dosage / Q000235:genetics / Q000302:isolation & purification; D007260:Infusion Pumps; D007278:Injections, Spinal; D051379:Mice; D016297:Mutagenesis, Site-Directed; D009185:Myelin Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D009412:Nerve Fibers / Q000502:physiology*; D009416:Nerve Regeneration / Q000187:drug effects*; D000070798:Nogo Proteins; D011712:Pyramidal Tracts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D051381:Rats; D011917:Rats, Inbred Lew; D011994:Recombinant Proteins / Q000008:administration & dosage* / Q000235:genetics / Q000302:isolation & purification; D020127:Recovery of Function / Q000187:drug effects; D013119:Spinal Cord Injuries / Q000188:drug therapy* / Q000473:pathology; D013904:Thoracic Vertebrae / Q000601:surgery
D006131:Growth Inhibitors; D007128:Immunoglobulin Fragments; D009185:Myelin Proteins; D000070798:Nogo Proteins; C000603199:RTN4 protein, human; D011994:Recombinant Proteins; C000603201:Rtn4 protein, mouse; C000603197:Rtn4 protein, rat