Accelerating effects of chitosan for healing at early phase of experimental open wound in dogs.

Chitosan is a polymeric beta(1 --> 4) glucosamine (2-amino-2-deoxy-D-glucose) and N-acetyl-D-glucosamine (2-acetamido-2-deoxy-D-glucose) which has been reported as a wound healing accelerator. In order to evaluate the efficacy of chitosan as an accelerator of wound healing, experimental open skin wounds were made on the dorsal side in three normal beagles. Cottonfiber-type chitosan (degree of acetylation = 18%) was applied for 15 days, and the process of wound healing was evaluated histologically and immunohistochemically. On day 3 postwounding, the chitosan-treated wounds showed histologically severe infiltration of polymorphonuclear (PMN) cells and an increase in effusion compared with that in the control. Granulation was more pronounced by the chitosan treatment on day 9 and 15 postwounding. Immunohistochemical typing of collagen I, III and IV showed increase of the production of type III collagen in the chitosan group. The appearance of mitotic cells occurred numerously in the control on postwounding day 3, and in the chitosan group on postwounding day 6. These results suggest chitosan to be having a function in the acceleration of infiltration of PMN cells at the early stage of wound healing, followed by the production of collagen by fibroblasts.