title: Sustained delivery of thermostabilized chABC enhances axonal sprouting and functional recovery after spinal cord injury.
abstract: Chondroitin sulfate proteoglycans (CSPGs) are a major class of axon growth inhibitors that are up-regulated after spinal cord injury (SCI) and contribute to regenerative failure. Chondroitinase ABC (chABC) digests glycosaminoglycan chains on CSPGs and can thereby overcome CSPG-mediated inhibition. But chABC loses its enzymatic activity rapidly at 37 degrees C, necessitating the use of repeated injections or local infusions for a period of days to weeks. These infusion systems are invasive, infection-prone, and clinically problematic. To overcome this limitation, we have thermostabilized chABC and developed a system for its sustained local delivery in vivo, obviating the need for chronically implanted catheters and pumps. Thermostabilized chABC remained active at 37 degrees C in vitro for up to 4 weeks. CSPG levels remained low in vivo up to 6 weeks post-SCI when thermostabilized chABC was delivered by a hydrogel-microtube scaffold system. Axonal growth and functional recovery following the sustained local release of thermostabilized chABC versus a single treatment of unstabilized chABC demonstrated significant differences in CSPG digestion. Animals treated with thermostabilized chABC in combination with sustained neurotrophin-3 delivery showed significant improvement in locomotor function and enhanced growth of cholera toxin B subunit-positive sensory axons and sprouting of serotonergic fibers. Therefore, improving chABC thermostability facilitates minimally invasive, sustained, local delivery of chABC that is potentially effective in overcoming CSPG-mediated regenerative failure. Combination therapy with thermostabilized chABC with neurotrophic factors enhances axonal regrowth, sprouting, and functional recovery after SCI.
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA.
authors.forename: Hyunjung
authors.initials: H
authors.lastname: Lee
authors.forename: Robert J
authors.initials: RJ
authors.lastname: McKeon
authors.forename: Ravi V
authors.initials: RV
authors.lastname: Bellamkonda
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology*; D019765:Chondroitin ABC Lyase / Q000008:administration & dosage* / Q000737:chemistry*; D016503:Drug Delivery Systems; D004795:Enzyme Stability; D006358:Hot Temperature; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012038:Regeneration; D013119:Spinal Cord Injuries / Q000188:drug therapy* / Q000503:physiopathology; D014199:Trehalose / Q000737:chemistry
chemical_list: D014199:Trehalose; D019765:Chondroitin ABC Lyase