title: Tetanus toxin fragment C as a vector to enhance delivery of proteins to the CNS.
abstract: The non-toxic neuronal binding domain of tetanus toxin (tetanus toxin fragment C, TTC) has been used as a vector to enhance delivery of potentially therapeutic proteins to motor neurons from the periphery following an intramuscular injection. The unique binding and transport properties of this 50-kDa polypeptide suggest that it might also enhance delivery of proteins to neurons after direct injection into the CNS. Using quantitative fluorimetry, we found that labeled TTC showed vastly superior retention within brain tissue after intracerebral injection compared to a control protein (bovine serum album). Fluorescence microscopy revealed that injected TTC was not retained solely in a restricted deposit along the needle track, but was distributed through gray matter in a pattern not previously described. The distribution of injected protein within the extracellular space of the gray matter and neuropil was also seen after injection of a recombinant fusion protein comprised of TTC linked to the enzyme superoxide dismutase (TTC-SOD-1). Injections of native SOD-1 in contrast showed only minimal retention of protein along the injection track. Immunohistochemistry demonstrated that both TTC and TTC-SOD-1 were distributed in a punctate perineuronal and intraneuronal pattern similar to that seen after their retrograde transport, suggesting localization primarily in synaptic boutons. This synaptic distribution was confirmed using HRP-labeled TTC with electron microscopy along with localization within neuronal endosomes. We conclude that TTC may be a useful vector to enhance neuronal delivery of potentially therapeutic enzymes or trophic factors following direct injection into the brain.
authors.affiliation: Cecil B. Day Laboratory for Neuromuscular Research, Massachusetts General Hospital, Building 114, 16th St., Room 3125, Charlestown, MA 02129, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Francis
authors.forename: E
authors.initials: E
authors.lastname: Bastia
authors.forename: C C
authors.initials: CC
authors.lastname: Matthews
authors.forename: D A
authors.initials: DA
authors.lastname: Parks
authors.forename: M A
authors.initials: MA
authors.lastname: Schwarzschild
authors.forename: R H
authors.initials: RH
authors.lastname: Brown
authors.forename: P S
authors.initials: PS
authors.lastname: Fishman
mesh_terms: D000818:Animals; D002490:Central Nervous System / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007202:Indicators and Reagents / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron; D010446:Peptide Fragments / Q000494:pharmacology*; D021382:Protein Sorting Signals / Q000187:drug effects* / Q000502:physiology; D013482:Superoxide Dismutase / Q000378:metabolism*; D000072105:Superoxide Dismutase-1; D013744:Tetanus Toxin / Q000494:pharmacology*; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D007202:Indicators and Reagents; D010446:Peptide Fragments; D021382:Protein Sorting Signals; C000606290:SOD1 protein, human; D013744:Tetanus Toxin; C040635:tetanus toxin fragment C; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1