The present invention generally relates to a combination of the fields of tissue engineering, drug discovery and drug development. It more specifically provides new methods and materials for testing the efficacy and safety of experimental drugs, defining the metabolic pathways of experimental drugs and characterizing the properties (e.g., side effects, new uses) of existing drugs. Preferably, evaluation is carried out in three-dimensional tissue-engineered systems, wherein drug toxicity, metabolism, interaction and/or efficacy can be determined.