Figure 6

The cellular and molecular composition of the scar in human SCI after long survival times. Transverse sections of the lesioned human spinal cord at 1 year (A-C) and 20 years (D-I) after injury. The schematic diagrams in the upper right corner indicate the region from where the actual picture was taken (black rectangle). A: NG2 staining revealed a network of irregular lamellae in the ECM at the lesion epicentre. B-C: In near adjacent sections, versican (B) and phosphacan (C) immunohistochemistry demonstrated fibre-like structures either singly or in small bundles. D: Twenty years after SCI, nerve root-like structures at the lesion epicentre demonstrated neurocan-positive myelin rings. E: In a near adjacent section, phosphacan immunoreactivity was also present in myelin sheaths surrounding axons in neuromas. F: Versican immunopositive myelin rings surrounding regenerated nerve fibres were more scattered and of a small diameter in the nerve root-like structures at the lesion epicentre. G: Twenty years after SCI, diffuse but elevated levels of NG2 immunoreactivity were still associated with the ECM of the connective tissue scar (lower part of image) as well as with the astroglial scar of the intermediate zone (upper part of image). At the lesion epicentre, NG2 staining was located on more loosely arranged sheets of basal lamina-like ECM. In the astrocytic scar, NG2 was associated with a dense irregular network of processes. Arrows demarcate the border between the connective tissue component of the lesion and the adjacent astrocytic scar. H: In a near adjacent section, diffuse phosphacan immunoreactivity was also associated with the dense network of processes of the astroglial scar. No immunoreactivity was associated with the ECM of the connective tissue scar. I: GFAP staining strictly delineated the interface between the astroglial scar and the connective tissue scar. (A-I magnification × 320).