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| Author | Topic: Stem Cell Technology |
| Fetal tissue graft restores lost sight |
posted 10/29/04 10:14 AM
New Scientist | AFP Thursday October 28, 02:00 PM Fetal tissue graft restores lost sight By Duncan Graham-Rowe Three years ago Elisabeth Bryant believed she would be blind for the rest of her life. “I couldn’t see anything,” she says. Now, although her vision is not perfect, she can see well enough to read, play computer games and check emails. Bryant has retinitis pigmentosa, an eye disease that has blinded four generations of her family. What has saved the sight in one of her eyes is a transplant of a sheet of retinal cells. The vision in this eye has improved from 20:800 to 20:84 in the two-and-a-half years since the transplant – a remarkable transformation. So far, six patients with either advanced retinitis pigmentosa or macular degeneration have had similar transplants. Together, these degenerative diseases are the biggest cause of blindness in rich countries, affecting tens of millions of people. While Bryant’s improvement is the most dramatic, four other patients have also had good results. When New Scientist print edition (1 February, 2003) reported the initial results of these retinal transplants, experts cautioned that the results could be due to the rescue effect: a short-term improvement triggered by the release of growth factors after eye surgery. That appears increasingly unlikely, because the rescue effect usually lasts only months. Reversing the incurable “We have shown the way,” says Robert Aramant at the University of Louisville in Kentucky, who developed the transplant technique with his colleague Magdalene Seiler. “It is possible to reverse these incurable diseases.” No other technique has come close to achieving this. The team has received approval from the US Food and Drug Administration to carry out further transplants on people with less advanced disease, and Aramant believes the results will be even better. There is a catch, of course. The sheets of retinal cells used by the team are harvested from aborted fetuses, which some people find objectionable. There is also a practical problem. Although millions of terminations are performed each year in the US alone, the fetal tissue is rarely donated. If further trials are successful and the technique starts to be widely used, there will not be enough tissue to meet demand. One accusation of those opposed to using fetal tissue is that women might be tempted to have abortions to provide tissue to restore their own sight or that of relatives. “People are going to claim that we are promoting abortion,” says Norman Radtke, the surgeon who carried out the transplants at the Norton Audubon Hospital in Louisville, Kentucky. Stem cell hopes A few countries, such as the UK, already have clear guidelines to ensure this does not happen. “The guidelines are meant to prevent the deliberate conception and termination for treatment of a particular person,” says Stephen Minger, head of the stem cell laboratory at King’s College London. In the US no such guidelines exist. Some of the other groups trying to develop treatments for degenerative eye diseases are pinning their hopes on stem cells. Various kinds can be turned into retinal cells, and this week it was reported that the eyes of people as old as 60 contain specific stem cells capable of forming all the different cell types in the retina. But the few attempts to treat degenerative eye diseases with stem cells in animals have failed, as have attempts to transplant unstructured groups of cells into the retina. Aramant and Seiler think the key to their success is that they transplant intact, 2-millimetre-square sheets of the upper retinal layer. This preserves the circuitry of the light-sensing cells, as well as the supporting cells that nourish them. Aramant is dismissive of the stem-cell work, pointing out that no one is anywhere near recreating the complex structure of the retina using stem cells. Instead, his team is examining the possibility of transplanting retinal sheets from pigs genetically engineered to reduce the chances of immune rejection. http://uk.news.yahoo.com/041028/12/f5hq9.html |
| Stem cells rebuild bladder control |
posted 12/1/04 1:00 PM
Stem cells rebuild bladder control 16:30 29 November 04 NewScientist.com news service Using a patient’s own stem cells to rebuild feeble bladder-control muscles may provide lasting relief from the embarrassing and inconvenient symptoms of urinary incontinence, a new study reveals. Activity-induced incontinence - a tiny tinkle when a person laughs or jogs, for example - is very common, affecting an estimated 10% to 35% of women globally. Also called stress incontinence, the loss of control is due to shrinking muscles in the bladder, sphincter, and urethra wall and becomes more likely as women age. In 1995, US sufferers alone spent $12.4 billion on drugs, adult incontinence pads and corrective surgeries. But even surgical treatments, such as collagen or liquid plastic injections to bulk up the urethra, are not permanent and can make it difficult to urinate. So Ferdinand Frauscher and his colleagues at University Hospital, Innsbruck, Austria wanted to see if stem cells could put the muscle power back, to re-establish natural control. Bladder controlled experiment The team removed a cube of muscle tissue, 4 millimetres to a side, from the biceps of 20 women, ranging in age from 36 to 84. Stem cells from the tissue were extracted and then grown in culture for six weeks, producing about 50 million myoblasts – the precursors of muscle fibres. “If you just inject 100,000 cells you can forget it. If you want to get a strong [bladder] sphincter muscle you must use a really large number of cells,” says Frauscher. Frauscher’s team injected the myoblasts into the urethra wall and bladder sphincter of each woman, using real-time ultrasound to make sure the cells made contact with their target. This contact is crucial as myoblasts need to be “told” in which direction they should grow by existing muscle fibres. The muscle-tissue extraction and stem-cell injection procedures each took about 15 minutes under local anaesthetic. Within 24 hours, 90% of the women had no urinary leakage. After two weeks, both doctor and patient could a see a marked increase in muscle tissue and contraction power under the ultrasound. Now, more than a later year, 18 of the 20 women have maintained full control over their bladders, says Frauscher, who presented the results at the Radiological Society of North America meeting in Chicago on Monday. The team is currently treating eight to 10 women per week and long waiting lists are building up. Christopher Woodhouse, at the Institute of Urology and Nephrology, University College London, is optimistic about the work. “At the moment, only God can make a sphincter. If you can make a muscle that relaxes and contracts in response to the body’s normal mechanisms, it would be a huge advance,” he told New Scientist. Anna Gosline http://www.newscientist.com/news/news.jsp?id=ns99996731 rebuilding humanity |
| Adult stem cells tackle multiple sc |
posted 12/1/04 1:11 PM
Adult stem cells tackle multiple sclerosis 19:00 16 April 03 NewScientist.com news service Treatment with adult stem cells has cured mice suffering with a form of multiple sclerosis, say Italian researchers. Almost a third of the mice recovered completely from paralysis of their back legs, and the rest all showed substantial improvement. "It was amazing," says Angelo Vescovi, of the San Raffaele Hospital in Milan. He has now begun experiments giving human adult stem cells to monkeys with the nerve and brain damage seen in MS. But he warns that success in mice does not guarantee success in humans: "I wouldn't want to raise expectations." Vescovi, Gianvito Martino and colleagues injected the diseased mice with stem cells that had been extracted from the brains of adult mice and multiplied in the lab. The cells were injected in the bloodstream or spinal cord. Postmortems on the mice showed that the stem cells had migrated to and then repaired damaged areas of the nerves and brain. In particular, the myelin sheaths of nerve cells were restored, after having been worn away. Seek and repair Demonstrating that stem cells can locate and repair a multitude of damaged sites by themselves is highly significant for the treatment of MS. "The problem with MS is that we don't know where the lesions are," says Vescovi. Vescovi stresses that his team's apparent success with adult stem cells should not used as a reason to halt research on embryonic stem cells. Pro-life groups object to research on ESCs because this involves the destruction of embryos aged up to 14 days. These groups argue that adult stem cells are just as promising for medical research. Although Vescovi does not think embryos should created solely to supply stem cells, he believes it is justified to extract them from spare IVF embryos that would otherwise be "put down the sink". The European parliament last week voted for draconian new laws to restrict research on embryonic stem cells and on cloning of cells to create tissues for transplant. But the most restrictive measures could be removed as the proposed laws pass through subsequent stages of the legislative process. Journal reference: Nature (vol 422, p 688) Andy Coghlan http://www.newscientist.com/news/news.jsp?id=ns99993638 rebuilding humanity |
| MS damage repaired by stem cells |
posted 12/1/04 1:38 PM
MS damage repaired by stem cells 11:49 21 January 03 NewScientist.com news service Damage caused by multiple sclerosis could be repaired using stem cells extracted from a patient's bone marrow, new research suggests. A team led by Bruce Brew at St Vincent's Hospital in Sydney, Australia, injected stem cells from mice and people into the brains of mice designed to act as models of human MS. Brew's team found that the stem cells were able to home in on areas of recent damage, and convert into oligodendrocytes - cells that manufacture myelin. Fatty myelin insulates nerve cells and is essential for effective signalling in the brain. But in patient's with MS, their own immune system attacks the myelin, causing progressive weakness, memory and vision problems. "We've been able to show that those stem cells differentiated into different sorts of brain cells - the most important of which was oligodendrocytes, the very cells that produce white matter," Brew says. It is not yet clear whether the new oligodendrocytes are capable of repairing myelin sufficiently to reduce symptoms. But the findings do suggest that patients "could conceivably have their deficits partly or wholly reversed", Brew says. Suppressed attack David Brittell of MS Australia welcomed the findings but stressed that any trials in people would be years away. Existing treatments for multiple sclerosis are designed to suppress the immune attack. At best, these drugs temporarily halt the progression of the disease. But there are other experimental procedures aimed at reversing MS symptoms. A team at Yale University has transplanted myelin-producing cells from the nerve in the ankle of one patient into her brain, for example. However, any treatment to repair damaged cells would have to be accompanied by immune-suppressing drugs, to prevent the new myelin being lost. Brew is hopeful his stem cell technique could be also used to tackle illnesses other than MS. "White matter in the brain is extremely important for function, so there are a whole host of deficits that could potentially be helped," such as meningitis and encephalitis, he says. Emma Young, Sydney http://www.newscientist.com/news/news.jsp?id=ns99993288 rebuilding humanity |
| Stem cells migrate from bone to bra |
posted 12/1/04 1:46 PM
Stem cells migrate from bone to brain 22:00 20 January 03 NewScientist.com news service Autopsies on four dead women have shown for the first time that stem cells in bone marrow can develop into brain cells, not just blood and bone cells as previously thought. The discovery suggests new approaches for repairing damaged or diseased brains. Stem cells themselves could be used, or the signalling chemicals that instruct them to become brain cells, although these have yet to be identified. "I think it's very encouraging to know that there are cells in the human bone marrow that have the capability to reach the brain and become neurons," says Eva Mezey, who led the team that made the discovery at the US National Institute of Neurological Diseases and Stroke in Bethesda, Maryland. The women whose brains were examined by autopsy had all been treated during their lives with bone marrow transplants from men. This meant that any cells the NINDS team found in the brain containing the male Y chromosome must have come from the donated bone marrow. The researchers found such cells and not just in isolation, but in clumps. This suggests the bone marrow stem cells multiplied after reaching the brain. Come here! Mezey's hunch is that the raw stem cells circulate all the time, until they are summoned to sites of injury. Once there, they are fashioned into tissue that heals the damage. "There's something that recruits these cells," says Mezey. "There's some factor that says: 'Come in here, we need you'. Then, they receive further orders as to what type of cell to become." "We must now find out what these signals are," she says. Doctors could potentially accelerate healing by injecting extra signalling molecules into damaged tissue. Look and learn Mezey's proposed strategy for finding the important signals would begin by identifying all the receptors on the surfaces of stem cells. This would reveal which signalling substances the cells are equipped to receive. The next step would be to expose stem cells to each substance in turn, and observe the type of cell they develop into. The NINDS team had already shown that bone marrow cells turn into brain cells in rodents. The new work now shows the same happens in humans. The findings corroborate experiments by Catherine Verfaillie of the University of Minnesota. These showed that special cells with stem-cell like properties, called "multipotent adult progenitor cells", could be isolated from the bone marrow of mice and humans. In mice, Verfaillie showed they turned into virtually any type of tissue. Verfaillie's discovery was reported by New Scientist in January 2002 and raised hopes that, for medical purposes, cells from an adult's bone marrow would be as suitable as the more controversial stem cells harvested from embryos. Journal reference: Proceedings of the National Academy of Sciences (DOI: /10.1073/pnas.0336479100) Andy Coghlan http://www.newscientist.com/news/news.jsp?id=ns99993286 rebuilding humanity |
| Scientists Discover Way To |
posted 12/1/04 2:08 PM
Scientists Discover Way To Regrow Teeth In Mammals 11-7-2 ALEXANDRIA, Virginia -- The Journal of Dental Research has published the results of the first successful regeneration of teeth. Researchers found that when cells obtained from immature teeth of sixth-month-old pigs were seeded onto biodegradable polymer scaffolds and placed in rat hosts, small, recognizable tooth crowns formed within 30 weeks. As published in the October 2002 issue of the Journal, researchers at The Forsyth Institute are the first to report using dissociated tooth tissues (tooth buds enzymatically digested into single cells) combined with polymer scaffolding (a technique used to form a pattern for human tissues and organs) to regenerate teeth. Researchers from other laboratories had previously used alternative approaches to form partial tooth structures including dentin and pulp, but none had grown complete structures that included enamel. The research also suggests the existence of dental stem cellsówhich could be key to bioengineering human teeth. ìThe ability to identify, isolate, and propagate dental stem cells to use in biological replacement tooth therapy has the potential to revolutionize dentistry,î said Dominick P. DePaola, DDS, PhD, president and chief executive officer of The Forsyth Institute, the independent research organization where the work was conducted. Dr. DePaola is also the Vice-president of the American Association for Dental Research, one of the publishers of the Journal of Dental Research. These recent findings emphasize the importance of dental and oral research, as well as the ongoing need for funding of projects. The research has resulted in coverage by not just the dental press, but also the general media worldwide. According to Mark C. Herzberg, DDS, PhD, Editor of the Journal and professor in the Department of Oral Sciences at the University of Minnesota, ìThe JDR publishes major scientific advances quickly and puts important and reliable information into the hands of the scientific community and the public. The JDR is a highly credible peer-reviewed publication, given the breadth of this recent international media coverage.î The Journal of Dental Research is published jointly by the International Association for Dental Research and the American Association for Dental Research, both based in Alexandria, Virginia. The JDR is the #1 dental journal in the world, with a Scientific Impact Factor of 3.35 (a measurement of its citation in other works) and a circulation of over 6,000. The International Association for Dental Research was established in 1920 to promote research in all aspects of oral and related sciences, to encourage development of improved methods for prevention and treatment of oral and dental diseases, and to facilitate cooperation among investigators and communication of research findings and their implications throughout the world. The IADR, a non-profit organization, has over 11,000 active individual members and over 100 institutional members worldwide. The American Association for Dental Research (a Division of the International Association for Dental Research) is a non-profit organization with over 6,000 individual members and 100 institutional members within the U.S. Contact Linda Hemphill Linda@iadr.org http://www.iadr.com/press/releases/10302.htm http://www.rense.com/general31/regrow.htm rebuilding humanity |
| Scientists plan teeth that regrow |
posted 12/1/04 2:51 PM
Scientists plan teeth that regrow Monday, May 3, 2004 Posted: 1127 GMT (1927 HKT) LONDON, England -- False teeth could become a thing of the past thanks to stem cell technology, scientists at London University say. Successful tests on mice show the technology may let people grow their own replacement teeth. The London team at Kings College have been awarded £500,000 ($887,500) to further their research and have set up a private company, Odontis, to develop their plans. The scientists say the technology will allow those with missing teeth to fill the gaps in their mouth without having to resort to false teeth, bridges or synthetic implants. The technology works by taking stem cells -- "master" cells that can be programmed to make different kinds of tissue -- from the patient which are treated and cultured in the lab. They are then re-implanted in the patient's jaw under the gum where the tooth is missing. Prof. Paul Sharpe, the genetic research scientist behind the technique, told the UK's Press Association that it was hoped the tooth would then grow into a fully-formed, live tooth in around two months. He said the technique had been tested in mice and they hoped to move on to trials in humans in the next two years. But it could be five years before the technology is widely available to the general public. The researchers are testing the success of stem cells taking from different parts of the body, such as from bone marrow or teeth themselves. Prof. Sharpe, head of division of Craniofacial Biology and Biomaterials at the Dental Institute at King's College, said the cost should not be more than the current price tag for synthetic implants -- around £1,500 ($2,660) -- £2,000 ($3,550). "A key advantage of our technology is that a living tooth can preserve the health of the surrounding tissues much better than artificial prosthesis," he told PA. "Teeth are living, and they are able to respond to a person's bite. "They move and in doing so they maintain the health of the surrounding gums and teeth," he said. In the UK and U.S., people over the age of 50 lose an average of 12 teeth from a full set of 32. Problems associated with loss of teeth include general health, nutrition and physical appearance. Prof. Sharpe's project has been awarded £300,000 ($532,500) from the Wellcome Trust, £100,000 ($177,500) from the National Endowment for Science, Technology and the Arts (NESTA) and £100,000 from a business sponsor. Mark White, invention and innovation director at NESTA, told PA: "Odontis have come up with a dental method that is highly innovative and pioneering in its approach. "We hope that our seed investment will bring about a major success story for the UK research and science community." A spokesman for the British Dental Association (BDA) told PA: "The BDA welcomes projects like Odontis and looks forward to seeing further progress in this field. "The BDA is also pleased to see the level of investment for this project from NESTA and hopes that future oral health projects will be given similar priority." http://edition.cnn.com/2004/WORLD/europe/05/03/teeth.replace/ rebuilding humanity |
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Zapped human eggs divide without sp (Moderator) |
posted 12/3/04 11:01 PM
New Scientist | AFP Thursday December 2, 03:00 PM Zapped human eggs divide without sperm By Andy Coghlan A trick that persuades human eggs to divide as if they have been fertilised could provide a source of embryonic stem cells that sidesteps ethical objections to existing techniques. It could also be deployed to improve the success rate of IVF. “Embryos” created by the procedure do not contain any paternal chromosomes – just two sets of chromosomes from the mother – and so cannot develop into babies. This should remove the ethical objections that some people have to harvesting from donated human embryos. There are high hopes that stem cells, which can develop into many different cell types, could be used to treat a range of diseases. The tricked eggs divide for four or five days until they reach 50 to 100 cells – the blastocyst stage. These blastocysts should in theory yield stem cells, but because they are parthenogenetic – produced from the egg only – they cannot be viewed as a potential human life, says Karl Swann of the University of Wales College of Medicine in Cardiff, UK. “This could eliminate one of the main sources of ethical controversy in this research,” says Bob Lanza, head of research at the cloning company Advanced Cell Technology in Worcester, Massachusetts. But Josephine Quintavalle of Comment on Reproductive Ethics, a London-based pro-life lobby group greeted the new procedure with caution. “I’d be happier if it was beyond all reasonable doubt that it could not become a human life.” She added that women must not be exploited to provide eggs. “Spark of life” Swann’s team tricked the eggs into dividing by injecting phospholipase C-zeta (PLC-zeta), an enzyme produced by sperm that Swann discovered two years ago with Cardiff colleague Tony Lai. “It’s the spark of life,” says Swann, who has previously showed that the human version of the protein can trigger mouse eggs to develop into blastocysts. “It tricks the egg into thinking it has been fertilised.” Human eggs contain two sets of chromosomes, one of which is normally jettisoned within two hours of fertilisation. Swann and his team used a standard chemical treatment to prevent this, so both sets in the parthenogenetic embryos come from the mother. The embryos appear to undergo the same changes as naturally fertilised eggs, producing waves of calcium ions across the cell every 20 to 30 minutes. Swann hopes to be the first to harvest embryonic stem cells from human parthenogenetic blastocysts, but other scientists are trying different approaches. In 2003, a team led by David Wininger, now at Wake Forest School of Medicine in North Carolina, grew parthenogenetic human blastocysts by stimulating eggs chemically ( New Scientist print edition, 26 April 2003). His approach involves triggering a calcium wave. “We don’t have a [stem] cell line yet, but it’s only a matter of time,” Wininger told New Scientist . A similar approach has yielded stem cells from parthenogenetic monkey blastocysts ( New Scientist print edition, 6 October 2001). PLC-zeta might also help women become pregnant through IVF. One IVF technique involves injecting sperm directly into eggs in the lab and then implanting them into the woman’s womb. Sometimes these embryos never begin dividing, perhaps because the sperm have defective PLC-zeta. Adding the enzyme artificially might start them dividing. Journal reference: Reproduction (vol 128, p 697) http://uk.news.yahoo.com/041202/12/f7rqa.html rebuilding humanity |
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Cloned human embryos deliver tailored stem cells (Moderator) |
posted 5/20/05 10:50 AM
Cloned human embryos deliver tailored stem cells 19:00 19 May 2005 NewScientist.com news service Rowan Hooper The possibility of growing your own tissue or organs in the lab for transplantation is a step closer following experiments that successfully cloned patient-specific stem cells. Woo Suk Hwang, of Seoul National University, South Korea, and colleagues, used an improved technique for cloning embryos to create stem cell lines for 11 patients with various diseases or injuries. The lines exactly match the patients’ nuclear DNA and immune system. “This is an enormous stride in the long journey to determine whether nuclear transfer-derived human embryonic stem cells might be eventually suitable for transplantation medicine,” said Gerald Schatten, at the University of Pittsburgh School of Medicine, and a member of the team. Many technical hurdles must be overcome before spare organs could be successfully grown. But scientists will use the new approach to create human cell lines for research on diseases such as autism, diabetes and Parkinson’s. The cell lines will also be used to screen drugs - at present, screening is conducted using animals. Rogue scientists Refining the techniques of human cloning for the development of new medical therapies could give encouragement to rogue scientists who wish to produce cloned babies. But the researchers insist this remains out of the question, both morally and scientifically. Hwang believes that human reproductive cloning is biologically impossible. And Mildred Cho, a biomedical ethicist at Stanford University, US, adds: “Irresponsible scientists might feel encouraged but there is no reason to believe this work significantly contributes to reproductive cloning.” The researchers extracted the nuclear DNA from skin cells of the 11 patients and inserted it into eggs donated by volunteers, having first emptied the eggs of their own DNA. The nuclear transfer technique is similar to that pioneered by the creators of Dolly the sheep at the Roslin Institute in Edinburgh, UK. The difference is that Hwang’s team’s process is far more efficient. Until recently it was not thought that nuclear transfer would even work in humans, but in 2004 Hwang’s team achieved it: They created 30 cloned human embryos and managed to harvest stem cells from one of them. Now, they have refined their technique and improved their efficiency tenfold, while also reducing their reliance on animal cells to feed the growing stem cells. The price of eggs “This paper has completely proven [adult] cell nuclear transfer as a technique in humans,” says Stephen Minger, of the Wolfson Centre for Age-Related Diseases, King’s College London, UK. In the US, eggs are in short supply and are often obtained from paid donors, but in Korea volunteers are plentiful. Eighteen women donated 185 eggs for research and, crucially, 125 of these were from women under the age of 30. The research suggests that it is the age of the egg donor which is important and not the age of the transferred DNA, which came from patients ranging in age from 2 to 56. Hwang’s laboratory is now way ahead of the field, says Minger, who recently visited the lab. They perfected their technique by performing some 1200 nuclear transfers every day on cells from sheep and cattle. Minger says that the quality of the science and the government support is as strong as anything he has seen in other labs and, in many cases, even better. “There is a good chance that the US will be left behind as the situation on stem cell research there becomes more fragmented and incoherent,” he adds. Journal reference: Science (DOI 10.1126/science.1112286) http://www.newscientist.com/article.ns?id=dn7401 |
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Stem cells from brains help rats walk, study says By Lisa Richwine (Moderator) |
posted 3/29/06 11:04 AM
Stem cells from brains help rats walk, study says By Lisa Richwine Tue Mar 28, 5:20 PM ET WASHINGTON (Reuters) - Stem cells harvested from the brains of mice can restore some walking ability in laboratory rats with spinal-cord damage, Canadian scientists reported on Tuesday. The findings are the latest success in rodent experiments to improve movement using a type of stem cell, an immature cell that can turn into different cells and tissues. Researchers hope to eventually test stem-cell therapies in people who are paralyzed and help them walk again. In the new study, scientists took cells known as neural precursor cells, a type of stem cell that has started turning into a central nervous system cell, from mouse brains. The researchers injected the cells into rats that could no longer walk after their spines were crushed, and gave them immune-suppressing drugs to prevent rejection. The cells migrated to the spinal cord, merged into the injured tissue and developed into cells that produced myelin, the insulating layer around nerve fibers that transmits signals to the brain. Many patients with spinal cord damage have intact nerve fibers at the point of injury but no myelin, causing paralysis. While the rats did not return to normal, they "recovered significant walking ability. They had better coordination of their joints and better ability to support their weight," said Dr. Michael Fehlings, a neurosurgeon at the Krembil Neuroscience Center at Toronto Western Research Institute. The research was funded in part by the Canadian Institutes of Health Research and published in the Journal of Neuroscience. MORE STUDIES NEEDED Fehlings said he was hopeful studies of a similar method in people could start in five to 10 years after more animal studies. One question to answer is why injections of stem cells given weeks after an injury appear less effective. In humans, researchers might be able to extract neural precursor cells by inserting a biopsy needle into a part of the brain where they believe the cells could be found, he said. If successful, the cells could be injected close to the injury site. Stem cells from the brains of human organ donors also could be a source, he said. "This type of strategy could potentially be relevant to about 50 percent of individuals with spinal cord injuries who still have enough nerves at the injury site but have lost myelin," Fehlings said. The research team said it was noteworthy that more than one-third of the stem cells survived after they were injected, moved to the injury site and produced myelin. The scientists also found the stem cells worked well when given up to two weeks after injury but less so when injected eight weeks later. Stem cells come from various sources, from bone marrow to fetal tissue to embryos. Use of stem cells from human embryos is controversial because some consider it immoral to destroy an embryo to get the cells. Other experiments have shown various types of cells can help heal spinal injuries in rodents. Last year, scientists reported improvement among mice with stem cells from aborted human fetuses and among rats with genetically engineered stem cells from rat embryos. http://news.yahoo.com/s/nm/20060328/sc_nm/science_stemcells_dc_1 |
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