Nicotine and methyl methane sulfonate in mini organ cultures of human parotid gland tissue

The aim was to demonstrate the applicability of using mini organ cultures (MOC) of the human parotid gland for indicating DNA damage by nicotine. Macroscopically healthy specimens of human parotid glands (1 mm3) were cultured for 7 d. Morphology was examined after HE and immunohistochemical staining of alpha-amylase. MOC were exposed to 2.0 mM nicotine or 100 microM methyl methane sulfonate (MMS) for 1, 2 and 3 h, followed by a regeneration period of 24 h. DNA damage was assessed by the comet assay. Histological findings demonstrated healthy acinar cells up to 8 days of culture and a strong expression pattern of alpha-amylase. Cells in the centre of mini organs showed a granular cytoplasm starting at day 3. 1-3 h nicotine exposure significantly increased DNA damage as determined by DNA in the tail (DT), with no significant differences with increasing exposure time and only a trend towards decreased values of DT after regeneration. MMS demonstrated a time-dependent increase in DNA damage and distinctly reduced DT values after regeneration. MOC may be used to study DNA damage and repair after repetitive exposure to xenobiotics. They provide additional information for in vitro studies of cells growing in an intact tissue structure.