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Monday April 27 10:39 PM EDT=20 Cloned brain cells may treat Parkinson's By Maggie Fox, Health and Science Correspondent=20 WASHINGTON (Reuters) - Researchers said Monday they had created a = possible new source for treating Parkinson's patients -- the brain cells = of cloned cattle.=20 Brain cells from cattle fetuses were genetically engineered, then cloned = and injected into rats with Parkinson's disease. The treatment seemed to = reduce the symptoms in the rats, the researchers reported in the journal = Nature Medicine.=20 They said they hoped the technique could one day be used in people.=20 The scientists' approach combined three new and controversial = technologies -- cloning, genetic engineering, and the use of fetal brain = cells to treat Parkinson's.=20 Dr. Curt Freed at the University of Colorado School of Medicine, Dr. = Steven Stice of the University of Massachusetts at Amherst and = colleagues said they had been intrigued by reports about brain cell = transplants for Parkinson's patients.=20 There is no cure for Parkinson's, a common brain disorder that causes = tremors and progresses to total muscle failure and death. It afflicts 1 = percent of people over the age of 50.=20 Victims have a shortage of dopamine -- an important brain chemical that = plays a role in muscular movement.=20 Research has shown that their dopamine-producing brain cells have = somehow been destroyed. But some experiments have shown Parkinson's = patients might be helped with injections of these brain cells from human = fetuses.=20 Aborted or miscarried fetuses have been the source, but using them is = highly controversial.=20 "A major problem for this emerging therapy is the limited and variable = supply of human fetal tissue," the researchers wrote in their report.=20 Earlier this year Stice's team reported they had cloned a small herd of = cattle using fetal cells -- not the difficult technique that produced = Dolly the sheep, cloned from an adult cell, but nonetheless a hard task. = They teamed up with Freed's group to see if such cloned fetuses might = help Parkinson's patients.=20 "Their study highlights some of the potential benefits of this = technology and will inevitably rekindle many of the debates about = cloning," Keith Campbell of Scotland-based PPL Therapeutics, the company = that cloned Dolly, said in a commentary.=20 The researchers cloned cattle fetuses, genetically engineered them, grew = them until their brain cells were at a certain stage, and removed the = brain cells. These brain cells -- neurons that produce dopamine -- were = injected into the brains of rats.=20 It is hard to tell with rats, but the animals displayed less "circling = behavior" -- one of the symptoms of Parkinson's in rats. The researchers = killed some of the rats and looked at their brains and saw that in many = cases, the injected cells had grafted onto their brains.=20 Using genetically engineered clones has two advantages -- genes can be = added to reduce the risk that the patient's immune system will reject = the cells, and scientists can produce cells that are exactly alike, with = an effect thus more predictable. The researchers think cattle fetuses = could have human genes added and be used as a source of brain cells. But = this calls for xenotransplantation -- using animal tissues in humans -- = which is another hotly debated area.=20 Scientists point out the risk of transmitting unknown diseases, and = changing some of the genes does not always do away with the risk of = rejection by the patient's immune system.=20