Decorin Attenuates Gliotic Scar Formation in the Rat Cerebral Hemisphere

Abstract

The transforming growth factor-βs (TGF-βs) are potent fibrogenic factors implicated in numerous CNS pathologies in which fibrosis and neural dysfunction are causally associated. In this study, we aimed to demonstrate significant inhibition of fibrogenesis, glial scarring, and inflammation in penetrating incisional wounds of the rat brain using the proteoglycan decorin, which effectively inhibits TGF-β activity. Adult rats were assigned to two treatment groups each receiving 14 daily intraventricular injections of 10 μl total volume of: (i) saline plus 0.3% autologous rat serum=30 μg protein); or (ii) saline plus 30 μg recombinant human decorin. On day 0 of the experiment, a stereotactically defined unilateral incisional lesion was placed through the cerebral cortex into the lateral ventricle and, after 14 days, brains were processed for immunohistochemical analysis of the lesion site. Specific antibodies were used to visualize the deposition within the wound of matrix molecules and the extent and nature of reactive astrocytosis and inflammation. Quantitative and qualitative image analysis of the fibrous scar was performed in sections from a defined anatomical plane through the wound to detect the antifibrotic effects of decorin treatment. Treatment of wounds with decorin led to a marked attenuation of all aspects of CNS scarring including matrix deposition, formation of an accessory glial limiting membrane, and inflammation. Our findings suggest that decorin is potentially applicable to a number of human CNS fibrotic diseases to arrest the deposition of excessive extracellular matrix components and maintain and/or restore functional integrity.