| 2005/05/20 (07:55) from 129.206.196.164' of 129.206.196.164' | Article Number : 199 |
LA Times
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| Scientists Clone Stem Cells From Human Patients |
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Scientists Clone Stem Cells From Human Patients By Karen Kaplan Times Staff Writer 3:16 PM PDT, May 19, 2005 South Korean scientists have surmounted a key hurdle in stem cell research, reporting today that they have produced 11 human embryo clones of injured or sick patients and harvested individualized stem cells in a process that could be used to treat patients with their own genetically matched tissues. The technique, reported by the same team that produced the first human embryo clones last year, also produced the stem cells with a much higher level of efficiency than in the past, boosting the technology well into the realm of medical therapy. If the technique can be replicated in other labs, scientists said they could create individualized lines of stem cells to produce tissues suitable for transplants without running the risk of rejection. They could also develop cell lines to study every type of cancer and all of the genes that contribute to diseases such as Alzheimer's, Parkinson's and juvenile diabetes. "It just opens a floodgate of possibilities," said Fred H. Gage, a professor of genetics at the Salk Institute in La Jolla. Ian Wilmut, the Scottish scientist who led the team that cloned Dolly the sheep in 1996, said patient-specific lines of embryonic stem cells could be created to produce new heart muscle to repair the damage from a heart attack, for instance, or fresh brain tissue to treat stroke victims. The researchers, who published their work in the online edition of the journal Science, insisted that their progress in cloning human embryos will not make things easier for anyone attempting to create a cloned baby, which they believe is impossible. "Reproductive cloning is not our goal," said Woo Suk Hwang, the lead researcher from Seoul National University. "Reproductive cloning is unsafe and unethical, and so it shouldn't be done in any country." The researchers collected 185 eggs from 18 women and removed the genetic material. They also took small skin biopsies — about the size of a small button — from 11 patients with spinal cord injuries, juvenile diabetes and a form of severe combined immunodeficiency disease, the so-called "bubble boy disease." After the skin samples were treated in the lab, the researchers took DNA from them and inserted it into the eggs. The procedure resulted in 31 embryos. When they were 5 days old, they were transferred to culture dishes, where 11 of them from nine patients developed into stem cells. Tests verified that the stem cells were able to multiply as well as differentiate into neurons, muscle, bone, cartilage, respiratory and islet cells, among others. On average, the researchers were able to produce a cell line using 16.8 eggs. In their previous paper, they required 242 eggs to create a single line of stem cells. Wilmut called this a "remarkable improvement in efficiency" that marks "a very significant step forward." Dr. Robert Schenken, president of the American Society for Reproductive Medicine, said the progress "should allay the concerns expressed by some critics that stem cell research would somehow lead to mass exploitation of women for their eggs." Scientists also said it was significant that the South Koreans were able to eliminate many of the animal products typically used in cells. A study earlier this year by Gage and others found that human stem cells nourished by tissue from mice, calves and other animals have incorporated a type of acid that would trigger a harmful immune response if transplanted into humans. Each of the advances reported in the paper is considered crucial to achieving the ultimate goal of customizing stem cells to treat individual patients, said Gerald Schatten, a biomedical researcher at the University of Pittsburgh who was a coauthor of the study. Researchers strongly suspect that tissues made from stem cells containing a patient's own genetic material are most likely to succeed in a transplant. "This may be nature's best repair kit," said Schatten, who leads the Pittsburgh Development Center, a biology research institute. The next step is to follow the recipe in the paper and create cells with a variety of genetic diseases to study "the cellular mechanisms that cause these diseases to occur," Gage said. For instance, Gage envisions creating a line of stem cells using the DNA of a patient with pancreatic cancer. "The embryonic stem cells don't have cancer, but they have the capacity for it," he said. "You could differentiate the cells into pancreatic cells and watch as the cancer develops." Scientists could use that information to develop a treatment that might prevent cancerous tumors from forming. When researchers are ready to test it, they could apply it to the cells and "see if we can interfere with the progress of the disease," he said. Ian Wilmut and Dr. Christopher Shaw, a neurologist at the Institute of Psychiatry in London, are already making plans to collaborate with Hwang's research group to produce embryonic stem cells cloned from patients with motor neuron disease. They hope the cells will allow them to zero in on causes of the disease and to test drugs that might provide cures. Schatten said Hwang is also collaborating with researchers at Memorial Sloan-Kettering Cancer Center in New York who focus on degenerative diseases like Parkinson's. "This work is powerful evidence that stem cell research can unlock the keys to understanding, and eventually treating conditions from spinal cord injuries to diabetes," said Daniel Perry, president of the Coalition for the Advancement of Medical Research. Although 60% of Americans support embryonic stem cell research, according to a poll conducted this month by Gallup, they remain uncomfortable with the idea of human cloning, with 87% of respondents calling it "morally wrong." That queasiness, in part, underlies the Bush administration's prohibition against using federal funds to develop or study stem cell lines created after 2001. Schatten pointed out that all of the experiments in the new study were conducted in South Korea without any U.S. funding. But he said the results might prompt Washington to reconsider its position. Congress is considering several bills that would expand the government's role in funding stem cell research. "Would I encourage a reevaluation of our policies now that we're nearly four years down the road?" he said. "Absolutely." |
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