 |
 |
Old affliction meets new science Scientists from across Canada try to uncover how brains can repair themselves after strokes with stem cells from their own bodies Tom Spears The Ottawa Citizen Tuesday, March 25, 2003 The brain withers during a stroke, as its blood supply is cut off and oxygen-starved neurons die. Once dead, these delicate cells are gone forever. People lose the ability to walk or talk or even to understand. Now, a $1.5-million project will link medical researchers across Canada in an unprecedented attempt to learn how the brains of stroke patients may repair themselves with stem cells from their own bodies. Twenty-five scientists in Ottawa and seven other cities hope to train stem cells from diverse parts of the body to travel to the brain's injured area, form themselves into brain cells, connect with other neurons -- and actually think. If it works, the achievement would be enormous. Fifty thousand Canadians will suffer a stroke this year, and 300,000 are living with the after-effects of an attack on the brain. This is where an age-old affliction meets a new wave in science. Stem cells are the body's construction materials. They are unfinished cells held in reserve, to be turned into bone or muscle or other specialized cells later, as the body grows or needs repairs. But they are also some of the least understood and elusive cells in our body. The Canadian Stroke Network and the Stem Cell Network are both based at the University of Ottawa, but link many labs and scientists across the country. This week they're announcing the start of Adult Stem Cells to Treat Stroke, a plan with an ungainly name that undertakes the most delicate work. Stem cells are a strong area for Canadians: Neural stem cells, for instance, were discovered here in the first place, as were stem cells in the retina of the eye. Now scientists in Ottawa, Toronto, Calgary, Edmonton, Lethbridge, London, Halifax and St. John's, Nfld. will try to put those cells to use fixing brain damage in animals. They will use a breathtakingly diverse set of materials -- stem cells that form in the brain along with others formed in the skin and in the bone marrow. Oddly, these cells from different areas aren't as different as they might seem. Fully formed neurons are nothing like skin or bone marrow. But cells that begin their existence in these different places don't necessarily stay there long enough to grow up. Like people, they can move to a new neighbourhood and turn out quite differently, so that a stem cell from skin becomes a brain or muscle cell. Doctors call this "plasticity." It's new and still controversial. "But if it's true and it holds up, this could be of phenomenal importance. You might be able to take stem cells from a part of the body where there's no disease and use them to treat and regenerate tissue in another part of the body where there is disease," says Ron Worton, scientific director of the Stem Cell Network. "What is exciting us is that they all seem to have, to a large or small degree, the ability to become brain cells," said Antoine Hakim, scientific director of the Canadian Stroke Network. "The research project at one level is to understand the biology ... How can we encourage them to become brain cells? "And then the question is, can we increase their availability to the brain?" This seems to mean putting the would-be brain cells into the bloodstream and finding ways to aim them, so that when they reach the brain they'll stop there, physically enter the brain's injured area and start developing into working neurons that communicate with established brain cells. It seems likely the brain does some of this work itself, calling stem cells to come and enter its injured area. The final question is the simplest: Will any of this help the patients to get out of wheelchairs? Talk again? Feed themselves? At the University of Calgary, the progress has already begun with rats that have grown back working brain cells -- and regained the ability to move their legs -- after suffering damage similar to a stroke. Calgary researchers caution the advance is still in its early stages. Yet they are clearly elated. The brain has a supply of stem cells naturally, and when there's damage it somehow senses the need to send these cells to the injury site for repairs. Yet in the case of a stroke, the number it sends "is vanishingly small," Calgary neuroscientist Sam Weiss explains. But in rats, his team is adding growth factors -- natural chemicals produced in the body to stimulate the building of new tissue. An extra dose of a growth factor can boost the number of stem cells sent to the stroke area by close to 10 times. "We've got to the point where we know you can get some sort of functional recovery" caused by new brain tissue forming, says Dr. Weiss. So far this only works in rats treated within a few days of the brain injury. Now they are measuring whether the animals can move their limbs in a useful way. "Can they even reach to grasp their food, for example? And that's very relevant to what happens when a human has a stroke." In the end, they'll test this kind of brain repair against repairs done with stem cells from the bone marrow and skin, "using the same animals, treated the same way and studied the same way," he says. "It's the first of its kind, doing that kind of a comprehensive, head- to-head comparison." The whole project depends on the kind of cross-country co- operation you can't find in much of the world. Last month, a Canadian public health expert just back from years in the United States was addressing a conference in Montreal. "If you could put all the genome experts in the United States in one room ..." he began, then stopped. Of course, he added, "they'd probably kill each other." His point was that Canada doesn't work that way. Scientists here get along. Maybe we're a more civil society; maybe, says Dr. Hakim. Our winters are so tough that we have to stick together. "We actually like working together." No one in the project knows where it will lead, yet they say any progress would be welcome. "The definition of a stroke is sudden. You're not prepared for it," says Dr. Hakim. "In a very short period of time you go from a fully productive member of the family to being handicapped." Weakened arms and legs are more or less accepted; much more frustrating for the patient and the whole family is the new difficulty in thinking and making decisions. Half the family members who take care of stroke patients seek psychiatric help for depression within a year. Dr. Hakim has seen surveys where patients rate their health on a scale of where five means perfect life and zero means death. Stroke victims sometimes pick a negative number. "They're rather be dead," he said. "So when you ask: What can we (stem cell researchers) give back with this? The answer is, anything would be OK. The ideal is like when you break a bone: Years later it's only a memory of something horrible." SOURCE: The Ottawa Citizen http://www.canada.com/ottawa/story.asp?id=%7BE77030DD-39A8-447F-8DD2- C2C1BC5C3079%7D * * * ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn