On behalf of BIOLAGO, Martina Keller-Ullrich spoke with the pharmacologist Prof. Dr. Marcel Leist, the only Baden-Württemberg scientist authorised to carry out research involving embryonic stem cells.

Initially, nothing much will change because it will take quite some time before we will actually be able to work with the new embryonic stem cells. We are required to send an application to the Robert Koch Institute, despite the fact that we’ve been authorised to work with stem cells since February.

Of course, and there are many reasons why this is the case. The first important reason is that up until the 1st of January 2002 only 18 stem cell lines were available. Most of them are about ten years old. Although they still function, i.e. still possess the ability to differentiate, they have of course gone through an ageing process. In addition, at the time these cell lines were created, little was known about the proper storage and growth of stem cells. Back then, they were cultured in bovine serum and were grown on connective tissue cells taken from the skin of mice. These cells have been in contact with animal material, something that poses a problem for many researchers, especially for those working on the human application of stem cells, for example the use of stem cells for transplantation.

Some of the new stem cell lines have gone through better control measures. In addition, and this is important for all those who work with stem cells, the new law provides us with more legal safety. In the past, we were in a kind of a legal grey area and it was difficult to judge whether we were doing something illegal or not. For example, German researchers could not work outside Germany with stem cells that were not approved for scientific application in Germany. Different legislation also made cooperation with international scientists very difficult.

In our department, we are investigating methods to replace animal experiments. We are particularly interested in how toxins affect the development of the nervous system. For example it is known that lead has a negative effect on human intelligence. At present, it is impossible to test many substances for their effects on brain and nervous system. We are hoping to use stem cells to investigate the effect of pesticides as early as possible. In the past, we used to work with mouse stem cells. However, these results cannot be directly transferred to the situation in humans. Human embryonic stem cells provide us with results that are of greater significance in terms of human application.

In addition, we are also involved in a new European project that deals with the development of medicines. The work with human stem cells might provide us with quicker and more reliable insights into whether a drug is toxic or not. This would also contribute to speeding up the drug development process.

This is a question that is often asked. But many people overlook the fact that there are not so many adult stem cells. On the other hand, only embryonic stem cells are able to differentiate into other cell types. A bone marrow stem cell is unable to become nervous tissue. Stem cells from the fatty tissue, although they are available in high enough numbers, cannot become neurons but only connective tissue, muscles or tendons. In addition, adult stem cells age a lot more rapidly and cannot be used as often as embryonic ones.

Perhaps we will no longer need stem cells in five to ten years’ time because a lot more will be known. If we succeed in elucidating what actually makes a stem cell a stem cell, then we might potentially be able to confer such stem cell properties on other cells artificially.

Of course, we have some basic knowledge on how the differentiation into different cell types works and there is continuous scientific progress in this area. The differentiation into different cell types during embryonic development is brought about by the addition of different hormones; in addition, we are able to influence stem cell growth by selecting a specific matrix in which to culture the cells. The time it takes to turn a stem cell into a nerve cell, for example, depends on the researcher’s skills. But in general, it takes about 40 to 60 days.

I have no problems in accepting that there are different opinions on this topic. However, I don’t like the “floodgate” argument which suggests that once the door has been opened it will be difficult to close it again. This argument means the end to any progress. I find that one has to push the limits. However, one must not cross them.

For me it is clear that certain rules have to be followed. The most important rule is that only “waste products” are used and in this respect one need not worry. It is not necessary to produce embryos specifically for research. No figures are available for Germany; but in the USA, approximately 400,000 embryos are stored in freezers. In vitro fertilisation involves the fertilisation of several eggs, of which only a few are selected for implantation into the womb. Those not required cannot be deep-frozen for more than five years and will simply be disposed of after this time.

We need a discussion about the principle problems, namely about how we should define what “becoming a human” means and when the rights of an individual should first be granted. Are these acquired gradually or are they just there at a certain time? The answers are different and depend on the religious or cultural background of the person asked. Questions on the time of death and transplantation also lead to controversial discussions. Ethical discussions require time, and time and experience will eventually lead to confidence that the right decisions have been made.

mek – 5th May 2008
© BIOPRO Baden-Württemberg GmbH

Further information:
Biological Faculty
University of Constance
Universitätsstraße 10
78467 Konstanz
Tel.: +49 (0)7531 88-5037
Fax: +49 (0)7531 88-5039
E-mail: marcel.leist@universität-konstanz.de