Within the biocompatibility assessment of i.e. medical devices or drug candidates, the in vitro test for cytotoxicity investigates the response of cells in culture to direct contact with devices or their extracts, or with different concentration of the drug to be tested.
The test devices or drug solutions are tested by exposure to the cell culture system (e.g., L929 mouse fibroblast cell line).
The in vitro cytotoxicity assay investigates L929 cell line upon the treatment with the respective test /control solutions for a determined time period.
After treatment, the medium is changed to XTT solution. The medium is transferred to a multiwell plate and measured by spectrophotometry.
The presence of any cytotoxic effect is indicated by loss of cell viability. The extent of cytotoxicity is evaluated with qualitative and quantitative method. Using XTT which is metabolically reduced in viable cells to a water-soluble formazan product, the number of viable cells correlates to the colour intensity determined by the photometric measurements.