Cytotoxicity testing
DIN EN ISO 10993-5:2009
This test is used to assess cytotoxicity for medical devices which have contact with human skin. L929 fibroblasts are exposed to different concentrations (e.g. 10%, 30%, 50%, 70% and 100%) of an extract of a medical device for 24 hours. After exposure, fibroblast morphology is evaluated (Prediction 1) and viability is assessed using the MTT test (colorimetric assay). If remaining viability is >70% the medical device is not cytotoxic (Prediction 2).
Prediction Model 1
| Morphology | Reactivity | Grading |
| discrete intracytoplasmic granule; no cellular dissolution; no inhibition of growth | none | 0 |
| not more than 20% of cells are round, loosely attached and without any intracytoplasmic granule or show changes in morphology; a few dissolved cells are present, only slight growth inhibition is noticeable | slight | 1 |
| not more than 50% of cells are round; free of intracytoplasmic granule; no extensive cell dissolution is detected; not more than 50% growth inhibition noticeable | mild | 2 |
| not more than 70% of cell layers contain round or dissolute cells; layers are not completely destroyed, but more than 50% growth inhibition is noticeable | moderate | 3 |
| almost complete or complete destruction of cell layers | severe | 4 |
Prediction Model 2
| Percentage of cell viability | Prediction |
| 100 – 70% | Not cytotoxic |
| 70 – 50% | Weakly cytotoxic |
| 50 – 30% | Moderately cytotoxic |
| 30 – 0% | Severely cytotoxic |
If viability is reduced to < 70% of the blank, the test item has cytotoxic potential.