Chitosan scaffolds appear to be suitable for a variety of tissue engineering applications. This study addressed the biocompatibility of chitosan in a mouse implantation model. Porous chitosan scaffolds were implanted in mice, and animals were sacrificed after 1, 2, 4, 8, or 12 weeks. Macroscopic inspection of the implantation site revealed no pathological inflammatory responses. Histological assessment indicated marked neutrophil accumulation within the implant, which resolved with increasing implantation time. Gram staining and limulus assays revealed no evidence of infection or endotoxin. Collagen was observed within the chitosan pore spaces, indicating that connective tissue matrix was deposited within the implant. Angiogenic activity associated with the external implant surface was also observed. Cellular immune responses were determined by lymphocyte proliferation assays, and antibody responses were measured using ELISA techniques. These assays indicated a very low incidence of chitosan-specific reactions. Although there was a large migration of neutrophils into the implantation area, there were minimal signs of any inflammatory reaction to the material itself. This preliminary study demonstrates that chitosan has a high degree of biocompatibility in this animal model. Overall, the findings suggest that chitosan may be suitable for the development of implantable materials.

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Quantitative analysis of peripheral nerve regeneration using nerve guides is commonly evaluated through histomorphometry and walking track analysis. We conducted a unique assessment of functional sciatic nerve recovery treated with chitosan nerve guides. We used video-gait analysis to evaluate the extent of functional nerve recovery by measuring the ankle angle at different gait cycle phases. We also correlated the gastrocnemius muscle weight measurements and histological analysis to functional nerve recovery. The chitosan group showed increased functional improvement compared to the control groups at the end of a 12-week period ( p < 0.05). Although both control and chitosan angle measurements were lower than those recorded for presurgery animals, the angle measurements significantly improved over the 12-week period. Stance phase duration of the gait cycle was also recorded, which showed a significant increase over the 12-week time period. The muscle weight parameter indicated a significant decrease in muscle atrophy and restoration of functional strength. Histological analysis revealed that the chitosan nerve guide provided significantly increased axonal growth. The functional results indicated that chitosan nerve guides enhanced functional improvement over no repair processes.