ABSTRACT
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.
ABSTRACT
The present interlaboratory validation study was performed in order to evaluate the use of Chinese hamster lung cell lines that employs crystal violet staining (CHL-CVS) as an alternative cytotoxicity test to the Draize eye irritation test (Draize test) for cosmetic ingredients. Ten substances, nine of which were surfactants, were evaluated at seven laboratories in the first phase of the validation study; 15 substances including dyes and lipids were evaluated at seven laboratories in the second phase of the validation study; 14 substances including acids and alkalis were evaluated at four laboratories in the third phase of the validation study. The logEC(50) values obtained for CHL-CVS were compared with the maximal average Draize total score (MAS) for a 10% (w/v) solution of 38 cosmetic ingredients as well as isotonic sodium chloride solution. The interlaboratory coefficient of variation (CV) for EC(50)s was 35.6%, which was considered to be within a tolerable range. The correlation coefficient and the Spearman's rank correlation coefficient between the in vitro and in vivo tests were -0.729 and 0.709, respectively. The prediction ability of the proposed method was assessed from the linear regression line for a MAS cut-off point of 15. According to this analysis, four substances (two alcohols and two acids) were determined to be false negative. The present study revealed the following characteristic factors of this method: (1) CHL-CVS could be applied to all the test substances including dyes and lipids in this study; (2) The results for medium-insoluble substances varied according to the laboratory; (3) The correlation between the in vivo and in vitro data for acids and alcohols (lower mono-ol) differed from that of the other substances. These results suggested that the CHL-CVS might have a potential to predict the Draize MAS if definite criteria can be established for the compounds to be applicable.
