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Chitin and chitosan (a deacetylated derivative of chitin) have been proposed for biomedical applications because of their biocompatibility and abundance in nature. We have investigated the effect of the percentage of deacetylation (%DD) of chitosan on biocompatibility from two sources, shrimp and cuttle fish, with two cell lines, L929 and BHK21(C13). The difference in %DD for each source was approximately 10% in the range of 76-90%. Biocompatibility was investigated for: (1) cell adherence and growth on the chitosan samples as substrate; (2) the effect of extract media on 2d and 7d growth; and (3) the presence of an inhibition zone. The results were similar for both cell lines. The chitosan samples were air-dried on to tissue culture-grade petri dishes to provide a substrate for the adherent-cell cultures. The higher %DD substrates from each source supported attachment of the cells, while the lower %DD did not. Cells cultured in medium conditioned by each substrate (i.e. extract medium) displayed an initial difference in growth which was abrogated in cultures incubated for 7 days. No inhibition zone was apparent. However, after 7 days, some cells were noted migrating on to the low %DD substrate disks. The morphology of these cells was changed with the presence of pseudopodia being apparent. Thus, especially with regard to attachment the %DD has a very important effect on the biocompatibility of the chitosan and should be monitored carefully.

The cytotoxicities of both homopolymers and copolymers of 2-hydroxyethyl methacrylate (HEMA) and various alkyl acrylates (AA) were investigated using cell culture techniques. The particular alkyl acrylates used were methyl acrylate (MA), ethyl acrylate (EA) and butyl acrylate (BA). The AA contents of the polymers studied were in the range of 0-25% by weight. They were synthesized via bulk polymerization in the form of thin sheets of 0.5+/-0.1 mm thickness. After sterilization using ethylene oxide gas, cytotoxicity tests, including both direct and indirect contact tests, were performed using cell lines of L929 and normal human dermal fibroblasts. The results showed that P(HEMA-co-EA) with EA contents of 15-25% and P(HEMA-co-BA) with BA contents of 10-25% appeared to be non-cytotoxic and attractive for more specific cytocompatibility tests and in vivo studies with a view to their use as temporary skin substitutes.