Figure 3. Drug development and drug validation strategies to reduce animal experiments.

Drug efficacy and drug toxicity profiles can be determined on medium-throughput level via tissue-specific spheroids, organoids or 3D bioprinted mini-tissues in multi-well plates. Read-outs for drug efficacy and toxicity are drug-target specific luminescence-based reporter assays (such as split-luciferase to measure protein–protein interaction in cells), viability assays and microscopy. Alternatively, tissue equivalents can be directly assembled in fluidic chip devices to achieve distinct tissue architectures or combine different tissue types. The overall goal is to refine parameters and reduce or even replace animal experiments by using human tissue surrogates.