Purpose: In accordance with OECD guidelines for testing of chemicals, animal models used for evaluation of skin irritation potentials of chemicals can be replaced with reconstructed human skin tissues because the results of the skin irritation test using the reconstructed skin tissues have been demonstrated to be comparable with those using animals. However, the procedure of the skin irritation test using the reconstructed tissues is also time-consuming and requires high costs. The skin irritation testing method using the reconstructed tissues evaluates the skin irritation potentials of chemicals based on changes in the tissue viability after treatment of the chemicals to the tissues. We thus hypothesized that the skin irritation potentials of cosmetic raw materials also could be preliminarily assessed through examining changes in human skin cells after adding the materials to the cells. Therefore, in this study we aimed to assess and compare changes in the viability of the reconstructed human skin tissues and human skin cells after treatment of different cosmetic raw materials that can be potentially used to prepare skin care cosmetic formulations.
Methods:
The skin irritation potentials of different cosmetic raw materials that can be used to prepare skin care cosmetic formulations were evaluated using the SkinEthicTM reconstructed human epidermis tissue (SkinEthic Laboratories, France) and human fibroblast cells (CCD-986sk cells and Detroit 551 cells, Korean Cell Line Bank, Korea). The tested materials included vinyl dimethicone+platinum divinyldisiloxane (VD-PDV), vinyl dimethicone+hydrogen dimethicone (VD-HDM), chitosan nanofibers, polydimethylsiloxane (PDMS) and polyphenyl-methylsiloxane (PPMS). The skin irritation test using the reconstructed tissues was performed based on protocols that were provided by manufacturers and reported elsewhere. Briefly, the reconstructed tissues placed in a 24-well plate were incubated during overnight at 37°C, 5% CO2 after arrival. The test materials were then added to the reconstructed tissues to attain a concentration of 10% (w/v) and incubated for 42 minutes. MTT assay was conducted to assess the tissue viability. As a negative control, phosphate buffered saline was added to the reconstructed tissues. In case of a positive control, sodium dodecyl sulfate was added to the tissues at a concentration of 5% (w/v). After the extraction procedure of formazan, the extract was transferred to a 96-well plate and the optical density was measured at 570 nm using a microplate reader. The relative viability of the reconstructed tissues to the negative control tissue was then calculated. In accordance with the European Classification System, the tested materials were determined to be irritant when the relative tissue viability was less than or equal to 50%.
For the assessment of skin irritation potentials of the test materials using human skin cells, CCD-986sk cells and Detroit 551 cells were cultured in 96-well plates to be confluent. The different cosmetic raw materials were then added to each well at the same concentrations described above. After the incubation period (42 min), MTT assay was performed to evaluate the relative cell viability to the negative control cells that were treated with distilled water. The correlation between skin irritation potentials of cosmetic raw materials examined by the different skin irritation testing methods was assessed by comparing the relative viability of the reconstructed tissues and the skin cells through student’s t-test. P value less than 0.05 was significantly different.
Taejun Jang
– Graduate Student, Chung-Ang University, Yongin-siSooho Yeo
– Graduate Student, Chung-Ang UniversityJaehwi Lee
– Professor, Chung-Ang University, Seoul-t'ukpyolsiTaejun Jang
– Graduate Student, Chung-Ang University, Yongin-si234 Views