Evaluation of the biocompatibility of a chitosan scaffold in mice

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. (C) 2001 John Wiley & Sons, Inc. J Biomed Mater Res 59: 585-590, 2002.