Interlaboratory Validation of the In Vitro Eye Irritation Tests for Cosmetic Ingredients. (6) Evaluation of MATREX((TM)).

MATREX(TM) is a test system for evaluating eye irritation potential, using the living dermal model (LDM). The LDM consists of normal human dermal fibroblasts in a contracted collagen lattice, which eventually forms a three-dimensional structure. This system has several advantages. It can be applied to insoluble substances and does not require sterile conditions for operation. In the present study, MATREX was introduced as an alternative to the Draize eye irritation test (Draize test) for cosmetics ingredients. MATREX was evaluated through a three-phase series interlaboratory validation as part of a joint project of the National Institute of Health Sciences (NIHS) and Japan Cosmetic Industry Association (JCIA). Toxicity for LDM was mainly evaluated by cytotoxicity, the indicator was EC(50) (concentration that inhibits the viability of the cell to 50% of control) value. Additionally, MATREX score indicating the grade of cytotoxicity was also introduced in the third phase of the validation study. Both test procedures were controlled under the same standard operating procedure (SOP), at all the participating laboratories. A total of 39 test substances both water-soluble and -insoluble were examined. LDM was applicable to almost all substances that could be evaluated by the Draize test. Furthermore interlaboratory variance was relatively low. The correlation coefficient between the EC(50) value and the maximal average Draize total score (MAS) was -0.672. The MATREX score was closely related to the EC(50) value. Moreover, the MATREX scoring method showed a similar prediction ability for eye irritation potential to the EC(50) method. Thus, the MATREX scoring method, a simplified EC(50) method, appears to be a viable alternative to the current EC(50) measurement method. The present results demonstrate the possibility that the MATREX system would form part of a prediction system of Draize test results.