The studies, which are published in Nature Genetics, show amongst other things, that hair follicle stem cells can divide actively and transport themselves through the skin tissue.

"The stem cells don't behave at all in the way we'd previously thought, and are found in unexpected places", says Professor Rune Toftg rd, one of the scientists at Karolinska Institutet responsible for the study. "We're now investigating the part played by the stem cells in the wound-healing process and the development of basal cell carcinoma, the most common form of skin cancer."

The stem cells examined by the present study are found in the skin's hair follicles, around which the cells are able to move depending on their stage of growth. The scientists believe that their growth is governed by previously known mechanism called Hedgehog signalling. Mutations in the genes that control this signal system can cause the delayed deactivation of signal transference; the signals thus continue uninhibited, which increases the risk of cancer.

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Mutations in cancer genes have also turned out to be far more complicated than people might have first suspected. Professor Mike Stratton, head of the Cancer Genome Project at the Wellcome Trust Sanger Institute in Cambridge, UK, led the team that mapped and identified the high-risk breast cancer susceptibility gene BRCA2. His group is searching for particular types of gene mutations in cancer cells, and is revealing new insights into a class of mutation called rearrangement, where one gene breaks and is fused to another. This rearrangement process could result in the creation of a rogue protein that promotes cancer. Until recently it has been difficult to study rearrangement mutations because technologies have been lacking. "For many years we have wanted a screen which would allow us to extract rearranged parts of the cancer genome and make a catalogue," Stratton told conference delegates. Techniques have now been developed that are allowing researchers to pinpoint rearrangements and look at them in detail. "New sequencing technologies are enabling us to look at a much larger number of rearrangements, allowing us to do genome-wide screens to identify fusion genes that could be cancer genes," Stratton said. "It turns out there is a lot of complexity in these rearrangements that we would not anticipated before we started." For example it is becoming clear that while there are many more rearrangement mutations than people first thought, the majority of these seem to be effectively harmless, or 'passenger' mutations. The significant mutations are the 'drivers', and these are much more elusive to track down.

Meanwhile Dr Kerstin Lindblad-Toh of Uppsala University in Sweden and the Broad Institute of MIT and Harvard, Cambridge, Massachusetts, is analysing gene mutations in different breeds of dog to throw light on human diseases. Because dogs have been reared as distinct breeds with clear isolated populations, it is often easier to detect a genetic flaw than it is in humans, and dogs are susceptible to many similar diseases that occur in man.

Professor Olli Kallioniemi's team at the Institute for Molecular Medicine in Finland is working on innovative ways to discover the effects of small strands of RNA, called small interfering RNAs (siRNAs), which can 'silence' genes and are showing promise in the fight against diseases such as cancer. The Finnish researchers have developed new high-throughput techniques for testing thousands of different siRNAs on living cells in one go. "This is a new cell array screening platform which we think has great potential for showing real utility in biological experiments," Kallioniemi told the meeting.

Professor Patrik Brundin of Lund University in Sweden leads a team that is learning how best to repair the brain of people with neurodegenerative disorders such as Parkinson's disease, where a part of the brain called the substantia nigra degenerates, leading to slow movement and tremors. Brundin told the meeting that his university has over the past 20 years transplanted brain tissue into 18 patients with Parkinson's, whose condition improved markedly and remained stable for many years. However, certain unexplained side effects have arisen, including uncontrollable movements. "Nigral transplants have clearly worked well in select cases, but the technique needs refinement and is difficult to perform in large series of patients," Brundin said. One key issue is a safe and sustainable supply of tissue, and embryonic stem cells could hold promise. However, Brundin warned that many hurdles remain to be overcome. "Today some people are saying that you can do this with stems cells, but stem cell transplantation to the brain is currently science fiction and should remain so for the moment - there are many challenges before we can do clinical trials."

In all, twelve key lectures were given at the meeting by leading scientists from Europe and the US. In addition there were more than 40 symposia, with topics ranging from the role of proteins in ageing to new ways to disable viruses that cause influenza.

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