A comparative study of chemically induced DNA damage in isolated nasal mucosa cells of humans and rats assessed by the alkaline comet assay

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 inter-individual differences were observed in human samples.