The ability of a substance to damage cells or tissue is referred to as cytotoxicity.
The test for cytotoxicity is one of the most important test methods within the scope of the biological evaluation of medical devices (standard series DIN EN ISO 10993). The objective of this evaluation is the safety of the medical device with regard to its use in or on human beings.
The in-vitro cytotoxicity test is of special importance here, as it detects any type of cytotoxic effect of a product, without, however, specifying the exact cause.
Fibroblasts (connective tissue cells) are used for this test, as they have a high sensitivity to toxic substances. The cells are either incubated with the product itself or with an extract of the product for several days. At the end of the incubation period, the cells are microscopically examined for morphological changes and altered growth behavior, and are then dyed to quantify the number of cells. From the ratio of the number of cells coming into contact with the product to control cells, the effect of the product on the growth (proliferation) of the cells can be determined and statements made on growth inhibition by the product.
A toxic effect can be caused by the product itself (material, coating) or by residues (e.g. of cleaning agents) or contamination on the product surface. This means that positive results in the in-vitro cytotoxicity test can lead to a number of additional tests to investigate the exact cause of the cytotoxic effect.