The first two authors contributed equally to this work.
Changes in distribution, cell associations, and protein expression levels of NG2, neurocan, phosphacan, brevican, versican V2, and tenascin-C during acute to chronic maturation of spinal cord scar tissue
Article first published online: 26 NOV 2002
Copyright © 2002 Wiley-Liss, Inc.
Journal of Neuroscience Research
Volume 71, Issue 3, pages 427–444, 1 February 2003
How to Cite
Tang, X., Davies, J. E. and Davies, S. J.A. (2003), Changes in distribution, cell associations, and protein expression levels of NG2, neurocan, phosphacan, brevican, versican V2, and tenascin-C during acute to chronic maturation of spinal cord scar tissue. J. Neurosci. Res., 71: 427–444. doi: 10.1002/jnr.10523
- Issue published online: 10 JAN 2003
- Article first published online: 26 NOV 2002
- Manuscript Accepted: 22 OCT 2002
- Manuscript Revised: 16 OCT 2002
- Manuscript Received: 30 AUG 2002
- Mission Connect—TIRR Foundation
- RGK Foundation
- inhibitory proteoglycans;
- glial scar;
- extracellular matrix
Previous studies have correlated the failure of axon regeneration after spinal cord injury with axons contacting scar tissue rich in chondroitin sulfate proteoglycans (CSPGs; Davies et al., 1999). In the present study, we have conducted immunohistochemical and quantitative Western blot analysis of five axon-growth-inhibitory CSPGs and tenascin-C within stab injuries of adult rat spinal cord at time points ranging from 24 hr to 6 months post injury. Quantitative Western blot analysis showed robust increases in neurocan, tenascin-C, and NG2 levels by 24 hr, suggesting that these molecules play a role in preventing axon regeneration across acutely forming scar tissue. Peak levels of 245/130 kD neurocan, NG2, and 250/200 kD tenascin-C were reached at 8 days, with maximum levels of phosphacan and 140/80 kD brevican attained later, at 1 month post injury. Versican V2 protein levels, however, displayed an opposite trend, dropping below unlesioned spinal cord values at all time points studied. Confocal microscopy at 8 days post injury revealed heightened immunoreactivity for phosphacan, NG2, and tenascin-C, particularly within fibronectin+ scar tissue at lesion centers. In contrast, neurocan was displayed within lesion margins on the processes of stellate NG2+ cells and, to a much lesser extent, by astrocytes. At 6 months post injury, 130 kD neurocan, brevican, and NG2 levels within chronic scar tissue remained significantly above control. Our results show novel expression patterns and cell associations of inhibitory CSPGs and tenascin-C that have important implications for axon regeneration across acute and chronic spinal cord scar tissue. © 2002 Wiley-Liss, Inc.