Delivery of thermostabilized chondroitinase ABC enhances axonal sprouting and functional recovery after spinal cord injury.
Degree: PhD, Biomedical Engineering, 2009, Georgia Tech
Chondroitin sulfate proteoglycans (CSPGs) are one major class of axon growth inhibitors that are upregulated and accumulated around the lesion site after spinal cord injury (SCI), and result in regenerative failure. To overcome CSPG-mediated inhibition, digestion of CSPGs with chondroitinase ABC (chABC) has been explored and it has shown promising results. chABC digests glycosaminoglycan chains on CSPGs and can thereby enhance axonal regeneration and promote functional recovery when delivered at the site of injury. However, chABC has a crucial limitation; it is thermally unstable and loses its enzymatic activity rapidly at 37 ºC. Therefore, it necessitates the use of repeated injections or local infusions with a pump for days to weeks to provide fresh chABC to retain its enzymatic activity. Maintaining these infusion systems is invasive and clinically problematic.
In this dissertation, three studies are reported that demonstrate our strategy to overcome current limitations of using chABC and develop a delivery system for facilitating chABC treatment after SCI: First, we enhanced the thermostability of chABC by adding trehalose, a protein stabilizer, and developed a system for its sustained local delivery in vivo. Enzymatic activity was assayed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and dimethylmethylene blue (DMMB), and conformational change of the enzyme was measured via circular dichroism (CD) with and without trehalose. When stabilized with trehalose, chABC remained enzymatically active at 37 ºC for up to 4 weeks in vitro. We developed a lipid microtube-agarose hydrogel delivery system for a sustained release and showed that chABC released from the delivery system is still functionally active and slowly released over 2 weeks in vitro. Second, the hydrogel-microtube system was used to locally deliver chABC over two weeks at the lesion site following a dorsal over hemisection injury at T10. The scaffold consisting of hydrogel and chABC loaded lipid microtubes was implanted at the top of the lesion site immediately following injury. To determine effectiveness of topical delivery of thermostabilized chABC, animal groups treated with single injection or gel scaffold implantation of chABC and penicillinase (P'ase) were included as controls. Two weeks after surgery, the functionality of released chABC and the cellular responses were examined by immunohistological analysis with 3B3, CS-56, GFAP and Wisteria floribunda agglutinin (WFA). The results demonstrated that thermostabilized chABC was successfully delivered slowly and locally without the need for an indwelling catheter by using the hydrogel-microtube delivery system in vivo. The results demonstrated that released chABC from the gel scaffold effectively digested CSPGs, and therefore, there were significant differences in CSPG digestion at the lesion site between groups treated with chABC loaded microtube-hydrogel scaffolds and controls. Third, a long term in vivo study (45 days) was conducted to examine axonal…
Advisors/Committee Members: Ravi V. Bellamkonda (Committee Chair), Andreas Bommarius (Committee Member), Andrés J. García (Committee Member), Niren Murthy (Committee Member), Robert J. McKeon (Committee Member).
Subjects/Keywords: Lipid microtube; Hydrogel; Regeneration; Chondroitin sulfate proteoglycan; Spinal cord injury; Chondroitinase ABC; Chondroitin sulfates; Protein engineering; Spinal cord Wounds and injuries; Spinal cord Regeneration
to Zotero / EndNote / Reference
APA (6th Edition):
Lee, H. (2009). Delivery of thermostabilized chondroitinase ABC enhances axonal sprouting and functional recovery after spinal cord injury. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/31734
Chicago Manual of Style (16th Edition):
Lee, Hyun-Jung. “Delivery of thermostabilized chondroitinase ABC enhances axonal sprouting and functional recovery after spinal cord injury.” 2009. Doctoral Dissertation, Georgia Tech. Accessed October 24, 2020.
MLA Handbook (7th Edition):
Lee, Hyun-Jung. “Delivery of thermostabilized chondroitinase ABC enhances axonal sprouting and functional recovery after spinal cord injury.” 2009. Web. 24 Oct 2020.
Lee H. Delivery of thermostabilized chondroitinase ABC enhances axonal sprouting and functional recovery after spinal cord injury. [Internet] [Doctoral dissertation]. Georgia Tech; 2009. [cited 2020 Oct 24].
Available from: http://hdl.handle.net/1853/31734.
Council of Science Editors:
Lee H. Delivery of thermostabilized chondroitinase ABC enhances axonal sprouting and functional recovery after spinal cord injury. [Doctoral Dissertation]. Georgia Tech; 2009. Available from: http://hdl.handle.net/1853/31734