The biological assessment of the chitin fibres

On the basis of carried laboratory tests of the aqueous extracts, such as pH evaluation, electric conductivity and dry residue assessment we can stated that the obtained results are within the limits of the standards and are comparable to these given for similar kinds of medical devices, e.g. for Dexon sutures: pH--6.10; electric conductivity--31 MicroScm-1; dry residue after evaporation--0.0014 g/100 cm3. The mean percentage of hemolysis counted from the three samples made for chitin extracts was 0.86% and did not exceed the value of 1% which is accepted by the standards. In the assessment of the cytotoxicity which was carried out on the mouse fibroblasts, the proper morphological character was stated. Agglutination, vacuolisation, nor cells membrane lysis were not observed. The number of cells separated from the matrix were identical as in the control cultures. The increased number of the dead cells and decreased proliferation of the cells in the cultures containing the chitin extracts, were probably due to the ethylene oxide residues, which was used for sterilisation of the fibres. The assessment of the intracutaneous reactivity of the chitin extracts showed the lack of the irritation influence and the index of primary irritation was of no importance at all. The pathomorphological findings, which included macroscopic and microscopic evaluation, specially carried out after the implantation, showed the greater biocompatibility of the tested chitin fibres in comparing them to the Maxon sutures. The healing process of these fibres included the short exudative phase, which was more significant than in Maxon sutures reaction followed by the proliferation phase, which ended with the development of the connective tissue capsule. The connective tissue penetrated among the single chitin fibres. After longer observation periods (more then 30 days) the thickness of the capsule decreased. The number of the chitin fibres did not change over the observations periods, however the change of the colour of the fibres was observed. In our opinion it is the sign that the process of resorption has already started. The tissue reactions after implantation of the chitin fibres can be compared to those observed for monofilament suture Maxon. On the basis of all these observations, assessments and findings we can stated that the chitin fibres fulfil the basic biological requirements set up for the bio-medical devices.