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Although questions have been raised regarding reproducibility and animal welfare, the rabbit Draize eye test has remained an accepted method to evaluate skin irritation for many years. For the last decade, in vitro 3D skin models are developed to predict and classify skin irritation potential of chemicals. Several methods have been validated by ECVAM (European Centre for the Validation of Alternative Methods) and achieved regulatory acceptance internationally for replacement of the rabbit Draize test. Among the approved skin systems is the Epiderm™ system from Matek. 

Epiderm™ is a 3D skin model derived from human epidermal keratinocytes which have been cultured to form a multilayered, highly differentiated model of the human epidermis (Figure 1). The model parallels human skin, and can provide a useful in vitro means to assess dermal irritancy and toxicology.


nl-3-14-fig2_s2Epiderm™ is proposed to be used as an ISO standardized test to evaluate skin irritation potential of medical devise extracts. The endpoint of the methods is cell death measured by the MTT test. The MTT test measures the conversion of MTT to a purple formazan salt (Figure 2) which is catalyzed by the enzyme SDH in viable cells. The conversion from MTT to formazan is a measure of cell viability which in this test is used to predict the irritation potential. In addition, Interleukine-1 alpha release can be measured in the medium as a secondary endpoint.

NIOM’s personnel have completed the course in the procedure of Epiderm™ skin irritation test and are approved to perform the method. The Epiderm™ test is now a part of the biological test battery at NIOM and manufacturers are welcome to order testing of their products.


Reference
Casas JW et al., In vitro human skin irritation test for evaluation of medical device extracts.
Toxicol In Vitro, 2013. 27(8): pp. 2175–2183.

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NIOM Newsletter March 2014