Abstract: Objective To observe the response of activated microglia/macrophages within and around the lesion site after rats' spinal cord injury treated with chitosan.Methods 35 adult female Wistar rats were randomly divided into the sham group (n=5), completely transection group (n=15) and chitosan treated group (n=15). The responses of activated microglia/macrophages on the 1st day, 3rd day, 7th day, and in the 2nd week and 4th week after surgery were examined by immunohistochemistry.Results Microglia/macrophages were fully activated and the number of these cells increased and got the highest level on the 3rd day post injury, then quickly decreased. In the chitosan treated animals, the microglia/macrophages were fully activated and the number increased to peak on the 7th day, then quickly decreased, there were still a few microglia/macrophages around the wound in the 2nd to 4th week after the treatment.Conclusion Microglia/macrophages could be recruited within and around the lesion area longer when treated by chitosan.

Key words: spinal cord injury, chitosan, microglia/macrophages