The open source concept - shaping the future of animal-free tests

Until today three epidermal equivalents, provided by only 2 different companies, have been validated as stand-alone replacements of animal tests for in vivo skin irritation testing. In addition, a human epidermal equivalent, based on an already published protocol, has been developed and evaluated for its use in a skin irritation assay. This skin equivalent is propagated as the Open Source Reconstructed Epidermis (OS-REp). This means that all underlying protocols and quality criteria for tissue production and irritation testings will be made public without any commercial or legal restrictions. The open source concept will have success only when the transferability of the protocols for substance testing and tissue production are proven and all defined quality criteria for the OS-REp are met. The results of a double-blinded study with 20 reference chemicals are currently reviewed by the ECVAM. The transfer of the production is currently investigated within the framework of a cooperation between the Henkel AG & Co. KGaA and the Fraunhofer Gesellschaft. The Fraunhofer Gesellschaft has started to adopt the Henkel protocol for the OS-REp production, aiming at producing the tissue equivalents fully automated with their proprietary "Tissue Factory". This strategy has the advantage not only to prove protocol transfer but also to enable high-scale tissue production under highly standardized conditions. First results concerning tissue quality are very promising. The tissue architecture of the OS-REp models produced at Fraunhofer either manually or automatically are indistinguishable from those models produced at the Henkel laboratory. Further experiments in order to reveal the suitability of the automatically produced OS-REp for skin irritation testings will follow in due time. Taken together, the open source concept is intended to pave the way towards an unrestricted access to in vitro test methods in future. In particular this concept is currently realized with the OS-REp epidermal equivalent as an alternative for skin irritation testings, to our knowledge for the first time in the framework of alternative methods.