The future of toxicity testing: the emerging role of organ-on-a-chip platforms

The 3Rs are guiding principles that must be followed when designing studies and conducting toxicity research. There is ongoing controversy regarding the use of animals in research. Moreover, the European Union outlawed animal experimentation in cosmetic products on 11 March 2013. More recently, the FDA Modernization Act 2.0 removed the requirement to use animal studies as part of the process for obtaining a licence for a biological product. These moral, ethical, and legal constraints have increased the need for alternative testing procedures. 3D cell cultures have gained popularity in recent years. Small microfluidic platforms known as "organs-on-chips" are dynamic cell cultures that mimic specific microenvironments. These microchips allow scientists to collect in vivo-like data. Organs-on-chips are considered a promising replacement for animal testing, and toxicity research is rapidly adopting this novel approach, much like other scientific fields, such as neuroscience, stem cell research, and cancer investigations. Therefore, the purpose of this review is to discuss the areas of toxicology where these platforms are currently being used, summarise the most recent toxicological applications of the aforementioned platforms, discuss the opportunities and challenges they present for toxicological research, and explore the interdisciplinary approaches applied within the field of toxicology.