Cytochrome P4502A6 stability in a mini organ culture model of human nasal mucosa for genotoxicology studies as detected by flow cytometry.

Three dimensional mini organ cultures (MOCs) of human nasal turbinate epithelia have been shown to be a relevant tool in genotoxicology studies. MOCs allow repetitive or chronic exposure of cells in an organ specific mucosal architecture for an extended period of time and monitoring of possible adverse effects with, e.g., the comet assay. It is the aim to demonstrate whether the proteins of key enzymes of xenobiotic metabolism, represented by cytochrome P450 2A6 (CYP2A6), remain on a stable level for a culture period that allows repetitive or chronic exposure to xenobiotics. Culture of mini organs was performed by cutting pieces of 1 mm(3) from fresh specimens of human nasal turbinates. MOCs of five tissue donors were incubated on multi-well plates with BEBM, on days 0, 4, 7, 9, and 11 aliquots were transmitted to flow cytometric quantification of the CYP2A6 protein. The CYP2A6 protein could be demonstrated on all days of culture investigated. Interindividual differences were more pronounced on day 0 than at later stages of culture. Although there appeared to be a slight decrease over the culture period, flow cytometric analysis did not reveal a significant loss of the signals up to day 11. The present data could show a pre-requisite of metabolic competence of MOCs that is in contrast to single cell cultures. Thus, this type of organ culture provides an in vitro model suitable for the assessment of genotoxic effects of environmental pollutants mimicking the in vivo situation with target cells of carcinogens in their functional organ specific architecture.