NERVE REGENERATION IN SILICONE TUBES - DISTRIBUTION OF MACROPHAGES AND INTERLEUKIN-1-BETA IN THE FORMED FIBRIN MATRIX

Macrophages have been regarded as important sources for different grow th stimulating factors in nerve regeneration. The distribution of macr ophages in the fibrin matrix, which is formed between the proximal and distal nerve stumps in silicone tubes [29], was investigated in rats. The sciatic nerves of rats were transected and the stumps were introd uced into a silicone tube: After 3, 6, 14 or 28 days, the distribution of macrophages (ED1 and ED2), the cytokine Interleukin-1 beta (IL-1 b eta), fibrin/fibrinogen, fibronectin, neurofilament and S-100 protein was investigated using immunocytochemistry. The pattern of fibrin/fibr inogen, fibronectin, neurofilament and S-100 protein was similar to pr eviously published data [29]. The matrices at 3 and 6 days, as well as the later regenerate, contained both ED1 and ED2 positive macrophages which was one of the cell types present. These cells were evenly dist ributed along the fibrin fibers or migrating cell columns. At the prox imal and distal nerve stumps, macrophages were more abundant in the pe rineurial tissue which was close to the silicone tube, except for more macrophages in the distal part. IL-1 beta was also present, especiall y at 3 and 6 days and evenly distributed in the matrix, but the intens ity of the staining decreased later. There was however no specific rel ation of ED1 or ED2 macrophage to the detected IL-1 beta. It is conclu ded that macrophages are trapped and present in the fibrin matrix form ed between the proximal and distal nerve stumps at an early stage of t he regeneration process and one of their products, IL-1 beta, was dist ributed in the matrix.