Before new creams, lotions or lipsticks are launched on the market, they have to be tested for possible skin reactions. However, experiments on animals within the cosmetics industry are no longer permitted in Germany. The alternative: a human skin tissue model. This allows not only cosmetics, but also pharmaceutical tinctures and chemicals to be tested quickly, cost-effectively and reliably. Dr. Thomas Graeve of the Fraunhofer-Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart has been awarded the Joseph von Fraunhofer Prize for his work in this field.

Color dyes in T-shirts, tensides in detergents, perfumed creams - our skin as the largest human organ is exposed to innumerable chemical ingredients every day. However, some of the substances can trigger allergies and skin irritations. Substances which come into contact with the skin were previously tested on animals for their potential to cause irritation. But such experiments are now prohibited in the German cosmetics industry. Instead, tissue models are being used more and more to test the effects of chemicals, pharmaceutical substances and skin creams. Many such methods of testing suffer from a serious shortcoming: Skin tissue models consist of just one single cell type - for example the upper layer of skin, the epidermis. Up to now it was not possible to test interactions with the lower layer of skin, the dermis, using these tissue cultures. This is how the three-dimensional skin tissue model developed by Dr. Thomas Graeve differs: It is composed of dermal fibroblasts (dermis) and a multi-layered epidermis with a keratinized layer. “The structure of this model comes very close to that of human skin“, Graeve explains. “The tissue-equivalent even forms an intermediate layer between the epidermis and the dermis, called the basallamina - just like natural skin.“ Researchers are using human skin tissue, from surgery for example, to construct the three-dimensional model. Two different cell types from the biopsy tissue are isolated: Dermal fibroblasts and keratinocytes, which form the dermis. The fibroblasts are first embedded in a protein solution, into which the keratinocytes are then seeded. The uppermost skin layer is then cultivated from the keratinocytes during a three-week period.

The skin tissue model is approximately the size of a fingernail and has a variety of possible applications. Certain body lotions can be tested using the skin tissue equivalent in order to determine whether they cause skin irritations or if individual substances trigger allergies. The system is also suitable for pharmacological tests. The healing properties of an ointment to treat burns can be tested, for example. “Using the skin tissue model, we are able to test substances more quickly, more cost-effectively and more reliably than through experiments with animals,“ Graeve emphasises. The model can even be used for immunological, histological and molecular-biological testing. The development of the test system was commissioned by the company CellSystems and is now being marketed all over the world. Two former members of the institute staff have also recognized the enormous potential of the skin tissue model. They are the founders of the company IN VITRO BIOTEC. Using tissues cultivated from human cells, the company tests skin reactions to chemicals and also the specific effects of cancer treatments.

Joseph von Fraunhofer Prize

Since 1978, the Fraunhofer-Gesellschaft has awarded annual prizes for outstanding scientific achievements by its staff, in finding solutions to application-related problems. The award amounts in each case to Euro 10,000.