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Bird brains offer stem cells hope Thursday, 24 February, 2000, 13:00 GMT - A new development concerning stem cells is keeping them at the forefront of biomedical research. Stem cells, it is believed, have the ability to develop into any other type of cell. Some scientists say that controlling them will herald a revolution in medicine and a new way to treat disease because it would open the way to cell replacement. In an intriguing example of this ongoing research scientists have used bird brains. They have coaxed new brain cells to grow from elusive adult stem cells. There are important implications for repairing human brains damaged by Parkinson's and Alzheimer's disease. By destroying certain brain cells in zebra finches the scientists say they have prompted the growth of new brain cells. Describing their research in the journal Neuron, they say they believe that neural stem cells must be the source of the new neurons. "This is, we believe, the first example where it has been demonstrated that one can induce the birth of new brain cells and that they actually contribute to a complex behaviour," said Jeffrey Macklis, a neuroscientist at Harvard University. "It is a step toward attempting the same in mammals" he added. The researchers chose zebra finches because of an interesting variation in bird biology. Canaries stop singing every autumn when a population of brain cells responsible for song-generation die. Over the winter, a whole new population of neurons grows back and in the spring the canaries learn their songs all over again. But zebra finches lack this seasonal cycle. Instead, their brains generate a continuous trickle of new neurons. Until recently scientists believed that brain cells did not regenerate but they now know that new cells do grow to a limited degree, especially in brain regions called the olfactory bulb and the hippocampus. One theory receiving serious attention holds that when certain neurons die, they signal stem cells to produce replacements. Macklis's team selectively killed one kind of song-related neuron in their zebra finches. The birds, as predicted, partly lost their ability to sing. But three months later they were singing as normal. When the researchers looked at their brains, they saw that the neurons had grown back, in much the same way that canary neurons come back. They say they are now performing more experiments to see just where the new cells came from but they suspect they coaxed stem cells into action. Stem cells are cells that can develop into other types of cells and as such they have the potential to be used to replace cells that have been lost of damaged. The new-found ability to grow stem cells from human embryos in the laboratory was hailed by Science magazine as one of the major breakthroughs of recent years. Scientists are trying to find ways to use either adult or embryonic stem cells, or both, to regenerate various forms of tissue, including brain cells of patients with disease such as Alzheimer's or Parkinson's. They are however difficult to isolate and grow. Controversially they can be taken from aborted foetuses or from embryos left over from IVF (test-tube) fertilisation programmes. In many countries this is illegal. Some researchers say that there may be a solution to the ethical problems of obtaining stem cells from embryos. Many tissues in the human body contain stem cells. Usually they develop into more cells of the tissues they are in but there is hope that they can be re-programmed. There is some recent evidence that they can be enticed to go back to an unspecialised 'blank' state. This line of research has the promise to obtain stem cells without using human embryos. By BBC News Online science editor Dr David Whitehouse BBC News Online: Sci/Tech http://news.bbc.co.uk/low/english/sci/tech/newsid_655000/655194.stm janet paterson 52 now / 41 dx / 37 onset a new voice: http://www.geocities.com/janet313/ 613 256 8340 PO Box 171 Almonte Ontario Canada K0A 1A0