INTRALABORATORY AND INTERLABORATORY EVALUATION OF THE EPIDERM 3D HUMAN RECONSTRUCTED SKIN MICRONUCLEUS (RSMN) ASSAY.

This study by scientists at Procter & Gamble Co., the Institute for In Vitro Sciences (IIVS), Advanced Testing Laboratory and MatTek Corp. demonstrated that an in vitro human reconstructed skin micronucleus assay (RSMN) based on MatTek’s EpiDerm in vitro human skin tissue equivalent exhibited the required intra and interlaboratory reproducibility with tissues produced from cells from different human donors to be considered a promising new in vitro genotoxicity assay that allows evaluation of chromosome damage following “in vivo-like” dermal exposures. A novel in vitro human reconstructed skin micronucleus (RSMN) assay has been developed using the EpiDerm™ 3D human skin model [R. D. Curren, G. C. Mun, D. P. Gibson, and M. J. Aardema, Development of a method for assessing micronucleus induction in a 3D human skin model EpiDerm, Mutat. Res. 607 (2006) 192–204]. The RSMN assay has potential use in genotoxicity assessments as a replacement for in vivo genotoxicity assays that will be banned starting in 2009 according to the EU 7th Amendment to the Cosmetics Directive. Utilizing EpiDerm tissues reconstructed with cells from four different donors, intralaboratory and interlaboratory reproducibility of the RSMN assay were examined. Seven chemicals were evaluated in three laboratories using a standard protocol. Each chemical was evaluated in at least two laboratories and in EpiDerm tissues from at least two different donors. Three model genotoxins, mitomycin C (MMC), vin-blastine sulfate (VB) and methyl methanesulfonate (MMS) induced significant, dose-related increases in cytotoxicity and MN induction in EpiDerm tissues. Conversely, four dermal non-carcinogens, 4-nitrophenol (4-NP), trichloroethylene (TCE), 2-ethyl-1,3-hexanediol (EHD), and 1,2-epoxydodecane (EDD) were negative in the RSMN assay. Results between tissues reconstructed from different donors were comparable. These results indicate the RSMN assay using the EpiDerm 3D human skin model is a promising new in vitro genotoxicity assay that allows evaluation of chromosome damage following “in vivo-like” dermal exposures.

7th Amendment to the Cosmetics Directive, Binucleate cells (BN), Chromosome damage, EPI-200-MNA, EpiDerm, Genotoxicity, Interlaboratory reproducibility, Micronucleus assay, REACH, RSMN, Reconstructed skin micronucleus assay

1,2-epoxdodecane, 2-ethyl-1,3-hexanediol, 4-nitrophenol, Acetone, Methyl methanesulfonate, Mitomycin C, Trichloroethylene, Vinblastine sulfate