Noriyuki Morikawa1, Katsuyasu Morota1, Shin-Ichiro Morita1, Hajime Kojima2, Satoru Nakata2 and Hiroaki Konishi2
Original paper :AATEX 9(1):1-10
When cultured skin models are used to evaluate skin irritancy, it is important that appropriate procedures for chemical application are utilized. In this study, we used several test substances and evaluated their skin irritancy by employing in vitro examinations, that is, evaluations of time scores for 50% cytotoxicity (ET50 values) and concentration scores for 50% cytotoxicity (EC50 values), and compared them to in vivo examination, that is, human patch test scores. There are great differences between chemical application procedures to predict skin irritancy. Therefore, to prevent both false negative and false positive results, we have developed a novel chemical application procedure, which is termed the post-incubation (PI) method. The PI method to evaluate EC50 values showed better correlation compared with other methods. In conclusion, considering the characteristics of these chemical application procedures, it is possible to confidently predict skin irritancy. It is also expected that cultured skin models will be very useful for purposes of predicting in vivo skin irritancy of chemicals and for studying mechanistic aspects of such irritancy.
Key words: cultured skin model, skin irritancy, EC50, ET50, human patch test