In order to reduce unneeded animal testing and possible cost and duration of testing, the ISO 10993 committee is looking to add an in vitro option to irritation testing. For the past 20 years, if you wanted to test for irritation, you had to do a version of the animal irritation test. The most common of these types of tests was a rabbit irritation test—a test where we inject or expose a rabbit to the sample or extract of the sample to look for redness or swelling, which are the signs of an irritation response.
For a while now, Europe has been pushing to outlaw and ban animal testing for cosmetics and chemicals. This requires an in vitro alternative to the common animal tests. The European Center for the Validation of Alternative Methods (ECVAM), has performed a large multi-million Euro validation on in vitro irritation tests.
In the tests, they took about a dozen chemicals, some known to be irritants and some known to be non-irritants. They tested to predict the irritation response from the chemicals using in vitro skin models. The ECVAM validation showed, after you expose these known irritants and known non-irritants to the tissue, you could accurately predict the irritation potential response from the chemicals using a cytoxicity test—usually the MTT test—on the tissue.
Currently, there are round-robin test validations going on among a variety of labs, including Nelson Laboratories, to demonstrate that medical device extracts can illicit the same predictive response with the irritation tests as those conducted by ECVAM. If the tests are successful, the in vitro tests can potentially become more efficient, use fewer or no animals, and save on costs and time.
FDA will not accept this testing for medical devices now, saying there is no proof that extractions can elicit a response. That is what the round robin testing is trying to show. Possible FDA approval will depend heavily on the round-robin results along with scientific discussion at the ISA level. FDA supports the testing.