In-vitro canine skin equivalents for veterinary therapeutics testing
Due to the large amounts of money spent on treatments in the companion animal sector, the global veterinary medicines market is a steadily growing market, with an estimated value of US$18.5 billion for 2021 . However, compared to human medicine, the market for veterinary medicines is poorly regulated. Therapeutics are used in this context even without prior testing for efficacy, often with minimal or no evaluated benefit. In addition, human therapeutics are often applied to animals, although pharmacodynamics and toxicological effects differ, sometimes significantly, on a species-specific basis. Therefore, species-specific testing is increasingly required for efficacy and risk assessment of veterinary therapeutics. In order to avoid controversial animal experiments at the same time, in- vitro test methods are suitable for this purpose.
Standardized testing of therapeutics and care products for dogs
Dermatological problems of pets, especially dogs, are among the most frequently occurring diseases in veterinary clinics. In the WowWowSkin project, the IGB is therefore developing an in- vitro model for canine skin (see Fig. 1) in order to be able to test therapeutic agents and care products for dogs in a standardized manner. To this end, (1) primary cells are isolated from canine skin biopsies, (2) they are genetically immortalized, and finally (3) used to construct canine full-thickness skin equivalents (see Fig. 2). The isolation of primary cells and their immortalization as well as the establishment of in- vitro skin models has been successfully performed with human material for decades in the Innovation Field Cell and Tissue Technologies. Based on this expertise, essential steps were adapted and optimized for the isolation of primary cells from canine biopsies. Primary keratinocytes, fibroblasts, endothelial cells and melanocytes were successfully isolated and expanded. These were immortalized by stable transfection with suitable plasmids to finally establish in in-vitro epidermis, dermis, and full-thickness skin models.