Replacement of the animal experiment for sensitization testing: development of an immunocompetent 3D skin model using pluripotent human stem cells

Abstract

The murine local lymph node assay (LLNA) and its non-radioactive alternatives (LLNA:DA & LLNA:BrdU-ELISA), as well as the Buehler guinea pig maximization test (OECD TG 406) are tests performed on laboratory animals to determine the sensitising potential of substances. There is a great need for alternative methods in this area. In fact, OECD test guidelines have already been published that depict individual steps in the pathway of sensitisation. These tests must be used together in a "test strategy", but are often inconclusive, so that animal testing must then be resorted to. The development of immunocompetent skin models with integrated epidermal dendritic cells offers a possibility for in vitro identification of skin-sensitising substances in the context of replacement. The generation of proliferation-active human skin cells is possible in a donor-specific and minimally invasive way from plucked hair follicles. Previously, dendritic cells were isolated from blood monocytes and always had to be re-isolated. So far, it has not been possible to integrate these immune cells into skin models. In the course of the present project, immune cell populations are now to be generated by reprogramming hair follicle cells into induced pluripotent stem cells (iPSC). These iPSCs can then be differentiated into the desired skin and immune cells and represent an innovative tool for generating an autologous test system as an alternative method. (AU)