Dynamic macroscale bioreactor systems are the most recent breakthrough in cell culture technology. This major achievement, at the beginning of the 21st century, fortunately coincided with an embarrassing gap in the measures to predict the safety and modes of action of chemicals, cosmetics, air particles and pharmaceuticals. The major hurdles to the translation of these breakthrough achievements of cell culture technology into meaningful solutions for predictive high throughput substance testing remain miniaturization from the milliliter to the microliter scale and the supply of relevant amounts of standardized human tissue. This chapter provides insights into the latest developments in this area, illustrates an original multi-micro-organ bioreactor concept and identifies highways for closing the gap.