Artificial liver for drug testing
The liver is one of the most important metabolic organs in humans. Johanna Schanz and Heike Mertsching, two scientists from Fraunhofer have developed a model of the liver that is both viable outside the body and suitable for testing drugs. For their work, the two researchers have been awarded the Technology for People award, along with a cheque for 10,000 euros.
If you suffer from fever, headaches or a cold, it is usually only a short distance to the nearest pharmacy. The drugs that you take, on the other hand, can take up to eight to ten years to develop. Animal experiments, which have always been an essential part of drug testing, continue to raise ethical problems. “Our artificial organ systems offer an alternative to animal testing,” said Prof. Heike Mertsching from the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart. “They also take into account the fact that humans and animals have different metabolisms. Thirty per cent of all side effects only come to light in human clinical trials which take place once the animal experiments have been completed.”
Dr. Johanna Schanz (left) and Prof. Heike Mertsching
© Fraunhofer/Dirk Mahler
The test system developed by Professor Mertsching and Dr. Johanna Schanz will give pharmaceutical companies more security in future as well as reducing the time needed for the development and release of new drugs. The two researchers were awarded the "Technik für den Menschen" (Technology for People) award for their achievements. The innovative liver model was presented on 23rd June 2009 in the news broadcast "Tagesschau" (ARD channel).
"The particularity of our liver model is that it is a functioning system of blood vessels," said Dr. Schanz. "We are able to create a natural environment for the cells." This is not the case in traditional systems, with the consequence that the cells very quickly become inactive. "Rather than building artificial blood vessels, we use existing ones taken from a piece of pig's intestine." All the pig cells are removed whilst the blood vessels are preserved. Two types of human cells are then seeded onto the resulting structure: hepatocytes, which break down drugs, and endothelial cells, which act as a barrier between blood and tissue cells. In order to stimulate circulation, the researchers put the model into a computer-controlled bioreactor with a flexible tube pump. This enables the nutrient solution to be fed in and transported away in the same way as in veins and arteries in humans. "The cells were active for up to three weeks," said Dr. Schanz. "This gave us enough time to analyse and evaluate the functions. However, a longer period of activity is also possible." The researchers found that the seeded cells work in a similar way to those in the body. They detoxify, break down drugs and build up proteins. These are all important preconditions for drug tests or transplants as the effect of a substance can change when transformed or broken down. Many drugs only become therapeutically active when metabolised in the liver, whilst others produce toxic substances.
The researchers were able to show the basic possibilities of the tissue models - liver, skin, intestine or trachea. The system is currently being tested. The researchers believe that their tissue model could provide an alternative to animal testing within two years.
Technology Prize - Technology for People
The prize is awarded by the former directors and institute heads of the Fraunhofer Society and associated external sponsors. The prize is awarded once every two years - the Stifterverband prize is awarded on alternate years - to Fraunhofer scientists who have made a considerable contribution to improving people's quality of life and enabling them to maintain their day-to-day capacities at whatever age. The prize, which comes with a cheque for 10,000 euros, was awarded on 23rd June 2009 at the annual meeting of the Fraunhofer Society in Munich.