Antoni Niekraszewicz

Reduction of post-traumatic neuroma and epineural scar formation in rat sciatic nerve by application of microcrystallic chitosan

Injury of peripheral nerve is associated with the development of post‐traumatic neuroma at the end of the proximal stump, often being the origin of neuropathic pain. This type of pain is therapy‐resistant and therefore extremely nagging for patients. We examined the influence of the microcrystallic chitosan gel applied to the proximal stump of totally transected sciatic nerve on the neuroma formation and neuropathic pain development in rats. In 14 rats, right sciatic nerve was transected and the distal stump was removed to avoid spontaneous rejoining. In the chitosan (experimental) group (n = 7), the proximal stump was covered with a thin layer of the microcrystallic chitosan gel. In control animals (n = 7), the cut nerve was left unsecured. Autotomy, an animal model of neuropathic pain, was monitored daily for 20 weeks following surgery. Then, the animals were perfused transcardially and the proximal stumps of sciatic nerves were dissected and subjected to histologic evaluation. The presence, size, and characteristics of neuromas as well as extraneural fibrosis were examined. In chitosan group, the incidence and the size of the neuroma were markedly reduced, as compared with the control group; however, there was no difference in autotomy behavior between groups. In addition, extraneural fibrosis was significantly reduced in chitosan group when compared to the control group. The results demonstrate beneficial influence of microcrystallic chitosan applied to the site of nerve transection on the development of post‐traumatic neuroma and reduction of extraneural fibrosis, however without reduction of neuropathic pain.

GPC Studies of Chitosan Degradation

Abstract Investigated were the changes in the molecular character of chitosan resulting from its degradation by the hydrolytic, radiation, and hydrolytic-enzymatic methods. It was found that under the influence of γ-60Co radiation, degradation proceeds in a manner implying a random breakup of the polymer chains with a systematic decline of sample polydispersity with increasing irradiation dose. In the hydrolytic and hydrolytic-enzymatic degradation processes the differences in the resulting changes depend on chain length. While the short macromolecules degrade similarly as by radiation, the longer chains degrade less readily, which can be inferred from the molecular weight distribution curves as well as from the polydispersity