The basis for all animal research: The 3R principle

Reduce – Replace – Refine

Animal research is only used if the findings cannot be obtained by any other methods. The foundation for this is known as the 3R principle (3Rs), to which all researchers are committed:

• Replace: Avoid animal research. If the same conclusions can be reached using alternative, animal-free methods, animal research can be avoided.
• Reduce: Use fewer animals. We conduct only as much animal research and use only as many animals as is absolutely necessary to achieve meaningful research results.
• Refine: Improve animal testing. Research should cause as little suffering and distress to animals as possible.

The 3Rs have since evolved into the 6R principle, which additionally includes Reproducibility, Responsibility, and Respect.

Alternatives and replacement methods

There are a number of methods that already make it possible to partially replace animal research. Using organoids, tissue engineering or virtual models, researchers can now solve many scientific questions that would previously have required animal research. These technologies are not yet sufficient to replace all animal research, but intensive research is underway – including at TU Dresden.

Organoids

Simplified human or animal organs, known as organoids, can be grown from individual cells. Researchers can observe the effects of certain manipulations, e.g. the addition of substances, on organoids more easily than in living organisms. However, it is not possible to model the interaction of the various organs and systems that make up a body in this way.

Various research groups at TUD already work with organoids and are continuously refining the method. Organiods play an essential role in cancer research at the University Hospital Dresden, for example. At the Center for Regenerative Therapies Dresden (CRTD) scientists are researching retinal organoids from human cells in order to understand the mechanisms and clinical pictures of the retina. In this way, they are doing important groundwork for new treatment options, e.g. for age-related blindness (age-related macular degeneration).

Tissue engineering and 3D bioprinting

By placing human or animal cells on three-dimensional tissue scaffolds, it is possible to manufacture tissue-like structures in a laboratory. These reproduce the real organs and tissues of the body much better than is possible in conventional cell culture experiments, in which the cells are cultivated as a thin layer in shallow plastic dishes.

3D bioprinting is a new variation of tissue engineering, in which cells are mixed with hydrogels and processed into three-dimensional tissue models with the help of a special 3D printer. This is advantageous over classic tissue engineering due to the higher degree of automation and easier integration of different cell types in different areas of the structure. At the Faculty of Medicine at TU Dresden, 3D bioprinting is being further developed and used to manufacture various tissue and organ models. In the long term, this will significantly reduce the volume of animal research.

In silico models

If we know enough about genes and their function, virtual models (in silico) of parts of the human body can be trained to react in approximately the same way as the human body. In the BCube, for example, the mechanisms that lead to gene mutations are observed and analyzed under different conditions in a virtual model. Since gene mutations can cause cancer, it is important to observe the development of mutations under as many different conditions as possible.