Is Animal Drug Testing Replaceable?

In vivo studies (animal testing) are used to confirm and approve the efficacy and safety of any drug. The objective is to identify how the drug will interact with body organs, tissues, or cells, as well as its possible toxicity.

The EU provides a wide range of legislation that protects animals used for scientific purposes. At present, all types of animal studies, such as the development or the production of new medicines, must be carried out in compliance with EU legislation. Furthermore, this legislation strictly favors the promotion of in vitro testing rather than animal testing. In fact, it applied different restrictions to highlight the value of animals over any commercial purpose. As a result, the EU prohibited animal testing for cosmetic drugs and restricted it to medical testing only.

While animal testing is restricted for medical use, the EU continues to work toward minimizing and eliminating the use of animal testing altogether. In many cases, biotechnology and in vitro testing are capable of replacing animal drug testing while continuing to secure their efficacy and safety. Before a drug or medicine is approved, liver toxicity studies should be conducted. These studies can be completed with in vitro models instead of animals by using human cells, 3D cell culture models, and micro-physiological (microfluidic) systems.

The use of human cells also yields more accurate hepatotoxicity detections, indicating that human in vitro testing is more effective and reliable. An additional method is the use of immortal cells or stem cells. Pluripotent stem cells have been found to culture and create hepatocyte cell structures resembling the structure of human hepatocytes. This allows for the application of in vitro metabolic and toxicity tests modeling in vivo tests.

However, primary human hepatocytes are currently considered to be the gold standard for hepatic in vitro culture models because they directly reflect the specific metabolism and functionality of the human liver. Maintaining liver parenchymal function ex vivo is essential to generate stable systems for efficacy and toxicology drug studies. For that, the use of 2D cultures, the co-culture of hepatic cells, the improvement of 3D culture models, or the development of microfluidic in vitrosystems recreate and mimic the hepatic microenvironment and minimize the use of the number of animals required. It is fundamental to identify the most appropriate microenvironment and cellular components in order to recapitulate in vitro the natural liver microarchitecture.