In the early stages of drug development, a drug's effect is tested in animal experiments.
For the first time, a 3-D liver model with a working blood circulation system makes it possible to obtain meaningful results from tests of new drug ingredients on human liver tissue.
Pharmaceutical companies invest huge amounts of money in the development of new drugs. To find out how the new substances act, the researchers usually take recourse to animal experiments. But the body of a mouse or a pig reacts differently to the human body. Even the results of tests performed on artificial or immortal cell cultures of human cells are only of limited validity. Scientists at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB have succeeded in producing different types of human tissue such as skin, liver and intestines. The liver model is of particular interest for drug tests. The special feature of the system is that the artificial tissue possesses a functional network of blood vessels. This is known by experts as a 3-D vascularized liver model.
So how do the scientists create three-dimensional tissue models that have their own blood supply? First, they take a piece of a pig’s small intestine, including an artery to supply the blood and a vein to carry it away. Then they remove the animal cells until all that remains besides the proteins of the connective tissue layer are the tubes of the vascular system, which branches out into tiny capillaries like a fan. The scientists line this plexus from the inside with human endothelial cells, as in the real-life archetype. As soon as artificial blood begins to circulate in the vascular system, cells of all kinds of organs can grow on the matrix. Since the tissue has its own blood circulation system, it can be kept alive in a bioreactor for weeks at a time. A computer controls the arterial pressure, the temperature and the flow speed.