Animal Models in Tissue Engineering. Part I.

Animal models play a central and pivotal role in tissue engineering. Although advances in areas such as 3D printing and bioreactor technologies now permit the in vitro development and testing of complex scaffold/cell composites, in vivo testing remains critical not only for refining methods being developed but also for the critical efficacy and safety testing required for regulatory approval. Yet, choosing the appropriate model for a particular application remains a challenge, as each model has its own strengths and weaknesses. In some cases, there are size issues to contend with as scale-up of a 3D structure brings with it considerable challenges with regard to diffusion, infiltration, and structural forces. In others, physiological differences between species make selection of the appropriate animal model that best represents the human disease or injury critical.