Molecular Changes in CSPG and Glial Scar Markers in Response to Subpial Chondroitinase ABC Treatment Following Spinal Cord Injury

Chondroitin sulphate proteoglycans (CSPGs) are major contributors to the inhibitory microenvironment that hinders regeneration following spinal cord injury (SCI). Chondroitinase ABC (ChABC) mediated degradation of CSPGs is associated with enhanced regenerative potential following SCI. In this study, the molecular responses of Neurocan, NG2 and Phosphacan CSPGs, as well as cellular markers for pro-inflammatory and neuroprotective microglia, astrocytes, oligodendrocytes and neurons, were investigated following a single subpial injection of ChABC (0.2 U in 10 μL) 14 days after thoracic (Th9) spinal cord compression in adult Wistar rats. qRT-PCR of samples from the lesion epicentre and adjacent cranial and caudal segments, 1 and 7 days after treatment, show that ChABC significantly suppressed Neurocan, NG2 and Phosphacan gene expression and reduced astrocytic (GFAP, S100B) and microglial/macrophage (Iba1, Cx3Cr1) reactivity after 24 h. Although most markers recovered within a week of ChABC delivery, sustained increases were observed for GAP-43, particularly in cranial and caudal segments, suggesting the potential regenerative benefits of ChABC. Correlation analyses revealed region-specific interactions between CSPG expression and glial phenotypes. Phosphacan displayed the strongest positive correlation with pro-inflammatory microglial/macrophage markers (IL-1β, iNOS) and the weakest with neuroprotective markers, suggesting a significant pro-inflammatory role. NG2 was associated with both pro- and anti-inflammatory markers, indicating a more balanced modulatory role, while Neurocan exhibited stronger correlations with neuroprotective markers. These findings highlight the importance of spatial and temporal context for SCI regenerative therapies targeting glial scar responses and support the therapeutic potential of subpial ChABC delivery for modifying the anti-regenerative inhibitory microenvironment following SCI.