cells go. iPS cells show telltale signs of motor neurons.
J. T. Dimos et al. Science express
Scientists say they have demonstrated the viability of a new way of studying the disease using a patient's own cells. Yesterday, a team from the universities of Harvard and Columbia announced that they have generated a population of motor neurons - the nerve cells that control muscle movement - from the skin cells of a 82-year-old woman with amyotrophic lateral sclerosis (ALS). These cells provide a way to take ALS studies "in the patient and in the Petri dish," Harvard biologist Kevin Eggan said at a press conference.
For many diseases, the researchers would like to study the diseased cells of a patient in the laboratory; their ultimate hope is that they can also fix these cells by modifying genetically and then reinjected into the patient. Until recently, scientists believed that the way to do it would be through therapeutic cloning, a controversial technique - still unproven for humans - which comprises the nucleus of a body cell into an enucleated egg. The resulting cells can then be induced to differentiate into any type of body tissue.
The ethical problems of using eggs can be circumvented with induced pluripotent stem (iPS) cells, which are adult cells reprogrammed to act like embryonic stem cells. In 06, researchers have created these mouse cells and rat by introducing a combination of four genes of a culture of skin cells. Then last year, the scientists showed that they could do the same with human cells . The new study, published online today by Science shows that iPS cells can be generated successfully, even from the skin cells of an elderly sick person, says Eggan.
ALS involves the progressive degeneration of motor neurons in the spinal cord, causing paralysis of the limbs and breathing. The team, led by Eggan and Christopher Henderson of Columbia University Medical Center, rose iPS cells by introducing four genes used in previous studies in about 30,000 cells from the patient's skin. Among the hundreds of colonies that developed from these cells, scientists found that a handful had markers of pluripotency. For these lines of iPS cells added the scientific molecules known to guide pluripotent mammalian cells into nerve cells. A significant proportion of them showed characteristic markers of motor neurons. Other tests - such as injection of the cells into mice or chicken embryos to see if they establish appropriate connections -. Will be needed to see if they are neurons full
The woman had a familial form of ALS caused by a mutation in the gene called superoxide dismutase 1 , or SOD1 , which is responsible for only 2% of ALS cases. Eighty-five percent of ALS cases are "sporadic" - meaning that there is no known inherited mutation; many probably result from genetic changes that occur through life interacting with environmental influences. However, Eggan said, "I think this approach has incredible promise to study other forms of ALS." Symptoms of family and sporadic forms of ALS are so similar, he added, they probably share many common mechanisms.
"It is exciting that they have created human cells from the patient material," says Jeffrey Rothstein cell researcher stem from Johns Hopkins University in Baltimore, Maryland, who is also studying ALS. But he warned that the cells are useful in research, they should be exactly the same as those that cause the disease in the patient. "You do not want a partial replica of the motor neuron," says Rothstein. iPS-generated neurons, they say he, perhaps of little use in the reproduction of the fate of motor cells buffeted by a lifetime of exposure to the drug and other metabolic and environmental influences.
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