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Title: Modifying chondroitin sulfation enhances retinal ganglion cell axon regeneration
Author: Pearson, Craig Steven
ISNI:       0000 0004 7652 4548
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2018
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The failure of mammalian CNS neurons to regenerate their axons derives from a combination of intrinsic deficits and extrinsic obstacles. Following injury, chondroitin sulfate proteoglycans (CSPGs) accumulate within the glial scar that forms at the lesion site in response to the insult. CSPGs inhibit axonal growth and regeneration, an action mediated by their sulfated glycosaminoglycan (GAG) chains, especially those with 4-sulfated (4S) sugars. Arylsulfatase B (ARSB) selectively cleaves 4S groups from the non-reducing ends of GAG chains without disrupting other, potentially growth-permissive motifs. In this thesis, "Modifying Chondroitin Sulfation Enhances Retinal Ganglion Cell Axon Regeneration," I, Craig Pearson, seek to determine the time course and spatial distribution of CSPG accumulation in the glial scar following acute injury, and then to demonstrate that ARSB is effective in reducing the inhibitory actions of CSPGs. I examine the effects of ARSB in an in vitro model of the glial scar and in vivo, using optic nerve crush (ONC) in adult mice. ARSB is clinically approved for replacement therapy in patients with mucopolysaccharidosis VI and therefore represents an attractive candidate for translation to the human CNS. My findings illustrate the importance of CSPGs as a barrier to axon extension following injury, and show compelling evidence that selective modification of the sulfation pattern on GAG chains results in significant enhancement of RGC axonal regeneration. Finally, I combine ARSB treatment with a host of intrinsic pro-regenerative stimuli and show robust, long-distance regeneration of RGC axons through the optic chiasm and into the optic tract. Taken together, the results of this thesis argue for the therapeutic potential of modifying the extracellular matrix to promote regeneration of axons in the CNS.
Supervisor: Martin, Keith Sponsor: Marshall Scholarship ; NIH Cambridge Scholarship
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: glaucoma ; regeneration ; retinal ganglion cell ; extracellular matrix ; nerve repair ; nerve regeneration