• Katalin Bartus, Nicholas D James, Athanasios Didangelos, Karen D Bosch, Joost Verhaagen, Rafael J Yáñez-Muñoz, John H Rogers, Bernard L Schneider, Elizabeth M Muir, and Elizabeth J Bradbury.
• King's College London, Regeneration Group, The Wolfson Centre for Age-Related Diseases, London SE1 1UL, United Kingdom, Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, 1105BA Amsterdam, The Netherlands, School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom, Department of Physiology Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, United Kingdom, and Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
• J. Neurosci. 2014 Apr 2; 34 (14): 4822-36.

AbstractChondroitin sulfate proteoglycans (CSPGs) inhibit repair following spinal cord injury. Here we use mammalian-compatible engineered chondroitinase ABC (ChABC) delivered via lentiviral vector (LV-ChABC) to explore the consequences of large-scale CSPG digestion for spinal cord repair. We demonstrate significantly reduced secondary injury pathology in adult rats following spinal contusion injury and LV-ChABC treatment, with reduced cavitation and enhanced preservation of spinal neurons and axons at 12 weeks postinjury, compared with control (LV-GFP)-treated animals. To understand these neuroprotective effects, we investigated early inflammatory changes following LV-ChABC treatment. Increased expression of the phagocytic macrophage marker CD68 at 3 d postinjury was followed by increased CD206 expression at 2 weeks, indicating that large-scale CSPG digestion can alter macrophage phenotype to favor alternatively activated M2 macrophages. Accordingly, ChABC treatment in vitro induced a significant increase in CD206 expression in unpolarized monocytes stimulated with conditioned medium from spinal-injured tissue explants. LV-ChABC also promoted the remodelling of specific CSPGs as well as enhanced vascularity, which was closely associated with CD206-positive macrophages. Neuroprotective effects of LV-ChABC corresponded with improved sensorimotor function, evident as early as 1 week postinjury, a time point when increased neuronal survival correlated with reduced apoptosis. Improved function was maintained into chronic injury stages, where improved axonal conduction and increased serotonergic innervation were also observed. Thus, we demonstrate that ChABC gene therapy can modulate secondary injury processes, with neuroprotective effects that lead to long-term improved functional outcome and reveal novel mechanistic evidence that modulation of macrophage phenotype may underlie these effects.

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