A Comparative Study of Chemically Induced DNA Damage in Isolated Nasal Mucosa Cells of Humans and Rats Assessed by the Alkaline Comet Assay

Abstract

Single-cell microgel electrophoresis (comet) assay was used to study genotoxic effects in human nasal mucosa cells and rat nasal and ethmoidal mucosa cells in vitro. Human cells were obtained from tissue samples of 10 patients (3 females/7 males), who underwent surgery (conchotomy) for treatment of nasal airway obstruction. Rat nasal mucosa cells were derived from male Sprague-Dawley rats. Cells were exposed for 1 h to either N-nitrosodiethanolamine (NDELA), epichlorohydrin (EPI), 1,2-epoxybutane (EPB), ethylene dibromide (EDB), or 1,2-dibromo-3-chloropropane (DBCP). Dimethyl sulfoxide (DMSO) was used as negative control. Alkaline comet assay was performed according to a standard protocol and DNA damage was quantified as Olive tail moment using image analysis system. All test substances induced an increase in DNA damage in human and rat cells. The absolute amount of DNA damage in rat nasal mucosa cells was usually higher than in ethmoidal mucosa cells. Human nasal mucosa cells were found to be less sensitive than rat mucosa cells to the genotoxic activities of DBCP (lowest effective concentration in human cells [LEC_human]: 1.5, in rat cells [LEC_rat]: 0.01 mM) and NDELA (LEC_human: 25, LEC_rat: 12.5 mM), whereas EPB-treated cells were almost equal (LEC_human and LEC_rat 0.78 mM). NDELA induced a marked concomitant cytotoxicity. For EPI (LEC_human and LEC_rat: 0.097 mM) and EDB (LEC_human: 0.195, LEC_rat: 0.048 mM), pronounced interindividual differences were observed in human samples.

The authors acknowledge Peter Schmezer (German Cancer Research Center, Division Toxicology and Cancer Risk Factors, Heidelberg, Germany) for his support and reading and commenting on the manuscript. We thank Joachim Wolf (formerly: Holz-Berufsgenossenschaft, München, Germany) for his support. We particularly thank Sabine Böhm and Sabine Franzen for their excellent technical assistance.