A widely used pharmacological test system for such
investigations are in vitro submerged cell cultures of
human keratinocytes as a dynamic proliferating and
differentiating system. This in vitro system represents
the complex differentiation process of epidermal skin,
leading to the anuclear cells filled with fibrous keratin
and getting plasticized by hydration (Ponec and Kempenaar,
1995; Gibbs et al., 1997; van der Sandt et al.,
1999). Beside toxic effects, different reaction patterns of
keratinocytes towards exogenous test compounds can
be detected using this system: compounds inducing cell
differentiation can be separated from substances promoting
the differentiation by increased formation of
keratins K1 and K10. Therefore submerged keratinocytes
allow detailed statements of potential mode of
action of the test compounds.