At Wickham Laboratories, we offer cytotoxicity testing for medical device biocompatibility to ISO 10993-5 / USP 87. These tests are in vitro (non animal) methods for assessing cytotoxic effects on living cells using cell culture techniques. For both of these methods, an extract of the device is made in cell culture media, which is then used to replace the media in an actively growing cell sheet. Incubation is continued for 24 hours in ISO 10993-5 and 48 hours for USP 87, after which the cells are scored for abnormalities or deaths as a percentage compared to the cell control. The number and size of the plaques is then estimated and recorded semi-quantitatively as non-cytotoxic, mildly cytotoxic, moderately cytotoxic or severely cytotoxic.
The cytotoxicity test is used as a precursor to toxicology work, assessing materials for an initial cytotoxic response in an effort to avoid unnecessary in vivo testing.
Our experts can offer two methods depending upon the nature of the medical device material:
Testing by extraction
- Suitable for most medical devices which may be tested as composite or individual components
- Cell monolayers are directly exposed to test and control material by means of fluid extracts
- Periodic microscopic examination at designated time points observe visible signs of cytotoxicity
- Include changes in size, shape or appearance of cellular contents in test and control material
- A change in appearance records a positive cytotoxic reaction.
Testing by agar overlay
- Indirect method suitable for testing transparent materials
- Examples of materials that can be tested include contact lenses or flat clear plastic parts
- Cell monolayer is cushioned with an agar overlay, on which test and control articles are placed
- Extractables from the sample will migrate through the agar layer to the cell monolayer
- Any cytotoxicity will create visible disruption to the cell layer directly below the article’s position
Please note that we are able to advise on the appropriate testing route for our clients to take and can outsource additional tests to several preferred sub-contractors if required.