Construction of three-dimensional human skin model involving dendritic cells and its application to skin sensitization test

Recently, to study an in vitro evaluation method of skin irritation and acute toxicity, many three-dimensional human skin models consisting of normal human keratinocytes and fibroblasts have been used. However, these skin models did not have any dendritic cells so were difficult to apply to an in vitro skin sensitization test. On the other hand, a single cell-culture model using normal human dendritic cells was recently studied for an in vitro evaluation method of immune-sensitizing compounds. However, these models have various problems: 1) the life span of dendritic cells is short(within 1 week) and 2) it is difficult to apply water-insoluble samples to these models. To study an alternative to animal testing using immune-sensitizing compounds, we therefore constructed a three-dimensional human skin model consisting of three different cells, dendritic cells (keratinocytes, and fibroblasts) then exposed immune-sensitizing compounds and non-sensitizers to the new skin model for 1 h and investigated the effect of these compounds on cytokine release and expression of CD86. Due to immune-sensitizing compounds, the new skin model significantly released cytokine and significantly expressed CD86. On the other hand, non-sensitizers did not induce IL-1alpha, IL-2, and IL- 4 release and expression of CD86. These results suggest that the new skin model is suitable for study as an alternative to animal testing using immune-sensitizing compounds.