Different in vitro and in vivo models have been developed to test drug delivery, toxicity, and biological efficacy of topically applied drugs or devices. In vitro bi-dimensional cell culture offers the possibility to investigate drug toxicity or efficacy towards selected cell types, while three-dimensional systems like reconstructed skin cultured at the air-liquid interface offer the possibility of mimicking several features of the skin barrier and to test effects on both keratinocytes and fibroblasts. However, these models do not comprise neither skin immune active cells (e.g., dendritic cells, macrophages, mast cells) nor skin appendages like hair follicles and sebaceous glands. Animal studies offer the possibility to include all physical and biological parameters of skin. However, beside ethical reasons, animal studies are expensive and results are not always reproducible in humans.
Ex vivo human skin has been used since years to test skin penetration of drugs but only in recent years skin organ culture has been used to develop models for specific skin diseases. In our group, different models have been developed to simulate inflammatory skin diseases, wound infections, and chronic wound healing (Figure 1). In these set-ups, skin is co-cultured with blood cells or inoculated with bacteria to reproduce
specific features of inflammation or infection and to test new therapeutic approaches such as wound dressings and exosomes derived from adult stem cells. Human full-thickness skin is a three- dimensional scaffold with a complex environment with extracellular enzymatic activity, inflammatory mediators, and several different immune active cells. These models are useful alternatives to pre-clinical animal studies for the investigation of topical skin treatments.
Dr.Fiorenza Rancan, Assistant Professorat the Charité Universitätsmedizin Berlin, has a degree in Pharmaceutical Chemistry and Technology at the University of Padua (Italy). She gained her PhD at the Humboldt University of Berlin (Germany) with a thesis on the biological effects of fullerene derivatives used is photodynamic therapy. She works since 2007 in the Clinical Research Center for Hair and Skin Science at the Charité– Universitätsmedizin Berlin in several interdisciplinary projects on transdermal vaccination, nanotoxicity, topical drug delivery, wound healing and wound infections.Current interests and projects are on topical antimicrobial treatments as well as ex vivo skin models as alternatives or complement to pre-clinical animal studies