When Stefan Fennrich received a telephone call, asking for his opinion on replacing animal testing with in vitro human blood testing, he was immediately thrilled by the idea. “This is brilliant,” said the enthusiastic physician and biochemist from Tübingen. The call was from Professor Thomas Hartung and Albrecht Wendel from the University of Constance who came up with the idea of the PyroDetect assay, which experts regard as a groundbreaking innovation in the effort to replace animal experiments.
Fennrich teamed up with Hartung and Wendel in 1997 and became the head of the PyroDetect development group in the Department of Biochemical Pharmacology at the University of Constance in 2005. "The PyroDetect assay is an excellent alternative to animal experiments and helps to save the lives of around 200,000 rabbits in Europe every year," said Fennrich. He also expects the new method to be used around the world and be able to save the lives of hundreds of thousands of experimental animals. The 53-year-old scientist can thus be regarded as the saviour of rabbits.
The idea developed from the fact that many patients depend on a daily injection of drugs. This process is associated with the risk that fever-inducing pyrogens are injected into the patient along with the drug. These heat-stable constituents of dead bacteria pose a great danger to human health and are frequently found to contaminate injection instruments. "Pyrogens can induce fever, lead to circulatory failure, multiple-organ failure, shock and in the worst case, even death," explained Fennrich. As the pyrogens pose a significant risk to human health, tests to detect potential fever-causing pyrogens in drugs are legally required worldwide. To date, such tests involve the use of rabbits. The drug to be tested is injected into the bloodstream of the rabbits which are subsequently fixed into tiny cages to record their body temperature for the duration of the test.
In addition to using animals, Stefan Fennrich also believes that pyrogen rabbit tests are affected by the problem that rabbits also react to stress, with the result that the test loses its reliability. "The innovative PyroDetect assay uses human blood to detect fever-inducing pyrogens. No animal experiments are required, and, what is equally important, the pyrogens are detected in the species, i.e. humans, which needs to inject a certain drug," said Fennrich. The development of the PyroDetect system also required the researchers to use rabbits, but only those rabbits that had already been used by the industry for pyrogen testing.
After 15 years of development, the groundbreaking method was introduced into the European Pharmacopoeia as an alternative to the rabbit test in 2010. According to Fennrich it was not easy to have the traditional rabbit test replaced by an alternative method. Fennrich is now the principal investigator in charge of blood compatibility testing in the research laboratory of the Department of Paediatric Cardiac Surgery at the University Hospital of Tübingen.
There may be more success on the way for Fennrich: The PyroDetect test can now be used for other applications, for example for measuring the quality of air. In addition, Fennrich has plans to expand the range of applications further, for example by extending the use of the method to medical products (e.g., cardiac valves or vascular prostheses) and cellular therapeutics (e.g. cartilage cell transplantations). Fennrich is still working closely together with his colleagues from Constance and wants to maintain this contact because it was here the idea of the PyroDetect test was born.