text: This undated image made available by the Oregon Health & Science University in May 2013 shows a stem cell colony developed from cloned human embryos. Scientists have finally recovered stem cells from... (Associated Press) 
   
   Scientists have finally recovered stem cells from cloned human embryos, a longstanding goal that could lead to new treatments for such illnesses as Parkinson's disease and diabetes. 
   
   A prominent expert called the work a landmark, but noted that a different, simpler technique now under development may prove more useful. 
   
   Stem cells can turn into any cell of the body, so scientists are interested in using them to create tissue for treating disease. Transplanting brain tissue might treat Parkinson's disorder, for example, and pancreatic tissue might be used for diabetes. 
   
   But transplants run the risk of rejection, so more than a decade ago, researchers proposed a way around that: Create tissue from stem cells that bear the patient's own DNA, obtained with a process called therapeutic cloning. 
   
   If DNA from a patient is put into a human egg, which is then grown into an early embryo, the stem cells from that embryo would provide a virtual genetic match. So in theory, tissues created from them would not be rejected by the patient. 
   
   That idea was met with some ethical objections because harvesting the stem cells involved destroying human embryos. 
   
   Scientists have tried to get stem cells from cloned human embryos for about a decade, but they've failed. Generally, that's because the embryos stopped developing before producing the cells. In 2004, a South Korean scientist claimed to have gotten stem cells from cloned human embryos, but that turned out to be a fraud. 
   
   In Wednesday's edition of the journal Cell, however, scientists in Oregon report harvesting stem cells from six embryos created from donated eggs. Two embryos had been given DNA from skin cells of a child with a genetic disorder, and the others had DNA from fetal skin cells. 
   
   Shoukhrat Mitalipov of the Oregon Health & Science University, who led the research, said the success came not from a single technical innovation, but from revising a series of steps in the process. He noted it had taken six years to reach the goal after doing it with monkey embryos. 
   
   Mitalipov also said that based on monkey work, he believes human embryos made with the technique could not develop into cloned babies, and he has no interest in trying to do that. Scientists have cloned more than a dozen kinds of mammals, starting with Dolly the sheep. 
   
   The new work was financed by the university and the Leducq Foundation in Paris. 
   
   Dr. George Daley, a stem cell expert at Children's Hospital Boston who didn't participate in the work, called the new results "one landmark step in a very long journey" toward creating DNA-matched transplant tissue. 
   
   Now, Daley said, scientists must compare the embryo-cloning approach with another technology that reprograms blood or skin cells directly into substitutes for embryonic stem cells. This reprogramming approach is technically simpler and doesn't involve embryos or require the donation of human eggs, and it was widely acclaimed when it was reported in 2007. Its Japanese developer shared a Nobel Prize last year. 
   
   But these substitute cells show some molecular differences compared to embryonic ones, which has led to questions about whether they can safely be used for treating patients. So it's essential to compare the cells from the two methods, Daley said. 
   
   The new results mean "we have another tool," he said. "We have to learn more about this tool." 
   
   Daley said he believed scientists will prefer using the reprogramming approach unless it can be proven "beyond a shadow of a doubt" that embryo cloning produces better cells for treating patients. 
   
   Mitalipov said he believed his technique would present a particular advantage for treating patients with a certain type of rare diseases. These are caused by mutations in genes of the mitochondria, the power plants of cells. He noted his technique, unlike the cell-reprogramming approach, would supply tissue with new mitochondrial genes that could replace defective ones. Those new genes would come from the egg. 
   
   The Rev. Tad Pacholczyk, director of education for National Catholic Bioethics Center, an independent think tank in Philadelphia, reiterated his opposition to embryo cloning, calling the approach unethical. 
   
   "It involves the decision to utilize early human beings as repositories for obtaining desired cells," he said. "You're creating them only to destroy them." 
   
   Marcy Darnovsky, executive director of the Center for Genetics and Society in Berkeley, California, said she was glad that Mitalipov doubted the embryos could be used to clone babies. She said the report still provides a good opportunity for the federal government to ban the use of cloning for reproduction. ||||| OHSU Photos 
   
   It was hailed some 15 years ago as the great hope for a biomedical revolution: the use of cloning techniques to create perfectly matched tissues that would someday cure ailments ranging from diabetes to Parkinson’s disease. Since then, the approach has been enveloped in ethical debate, tainted by fraud and, in recent years, overshadowed by a competing technology. Most groups gave up long ago on the finicky core method — production of patient-specific embryonic stem cells (ESCs) from cloning. A quieter debate followed: do we still need ‘therapeutic’ cloning? 
   
   A paper published this week1 by Shoukhrat Mitalipov, a reproductive biology specialist at the Oregon Health and Science University in Beaverton, and his colleagues is sure to rekindle that debate. Mitalipov and his team have finally created patient-specific ESCs through cloning, and they are keen to prove that the technology is worth pursuing. 
   
   Therapeutic cloning, or somatic-cell nuclear transfer (SCNT), begins with the same process used to create Dolly, the famous cloned sheep, in 1996. A donor cell from a body tissue such as skin is fused with an unfertilized egg from which the nucleus has been removed. The egg ‘reprograms’ the DNA in the donor cell to an embryonic state and divides until it has reached the early, blastocyst stage. The cells are then harvested and cultured to create a stable cell line that is genetically matched to the donor and that can become almost any cell type in the human body. 
   
   Many scientists have tried to create human SCNT cell lines; none had succeeded until now. Most infamously, Woo Suk Hwang of Seoul National University in South Korea used hundreds of human eggs to report two successes, in 2004 and 2005. Both turned out to be fabricated. Other researchers made some headway. Mitalipov created SCNT lines in monkeys2 in 2007. And Dieter Egli, a regenerative medicine specialist at the New York Stem Cell Foundation, successfully produced human SCNT lines3, but only when the egg’s nucleus was left in the cell. As a result, the cells had abnormal numbers of chromosomes, limiting their use. 
   
   Monkeying around 
   
   Mitalipov and his group began work on their new study last September, using eggs from young donors recruited through a university advertising campaign. In December, after some false starts, cells from four cloned embryos that Mitalipov had engineered began to grow. “It looks like colonies, it looks like colonies,” he kept thinking. Masahito Tachibana, a fertility specialist from Sendai, Japan, who is finishing a 5-year stint in Mitalipov’s laboratory, nervously sectioned the 1-millimetre-wide clumps of cells and transferred them to new culture plates, where they continued to grow — evidence of success. Mitalipov cancelled his holiday plans. “I was happy to spend Christmas culturing cells,” he says. “My family understood.” 
   
   The success came through minor technical tweaks. The researchers used inactivated Sendai virus (known to induce fusion of cells) to unite the egg and body cells, and an electric jolt to activate embryo development. When their first attempts produced six blastocysts but no stable cell lines, they added caffeine, which protects the egg from premature activation. 
   
   None of these techniques is new, but the researchers tested them in various combinations in more than 1,000 monkey eggs before moving on to human cells. “They made the right improvements to the protocol,” says Egli. “It’s big news. It’s convincing. I believe it.” 
   
   The experiments took only a few months, Mitalipov says. “People say, you did it in monkeys in 2007. Why did it take six years in humans?” Most of the time, he says, was spent navigating US regulations on embryo research. 
   
   The researchers carried out a battery of tests to prove that their SCNT cells could form various cell types, including heart cells that are able to contract spontaneously. 
   
   Their first cell lines were created using fetal skin cells; others were derived using donor cells from an 8-month-old patient with a rare metabolic disorder called Leigh syndrome, to prove that ESCs could be made from more mature donor cells. The technique does not require prohibitive numbers of eggs: it took 15 from one donor to produce one cell line and 5 from a different donor to make another. “The efficiency was the most impressive thing,” says George Daley, a stem-cell expert at Children’s Hospital Boston in Massachusetts. 
   
   Such improvements might be necessary to convince people that SCNT research is still worthwhile. Egg donors for the experiment received US$3,000–7,000 in compensation. This is expensive and, according to some bioethicists, risks creating an organ trade that preys on the poor. Because the technique requires the destruction of embryos, funds from the US National Institutes of Health (NIH) cannot be used to make or study SCNT-derived cell lines, hampering further clinical research. (Mitalipov maintains a separate laboratory for NIH-funded research.) 
   
   Public fears that the technology might be used to create human clones are another sticking point. The research might spark “cloning hysteria” that opponents of stem-cell research could capitalize on, says Bernard Siegel, executive director of the Genetics Policy Institute in Palm Beach, Florida. But Mitalipov has tried without success for more than a decade to produce a monkey by cloning. Tachibana says that an upcoming publication will explain why reproductive cloning of humans is not possible using their SCNT technique. 
   
   Still, Daley and most other stem-cell researchers have shifted to another method for creating genetically matched, patient-specific cell lines: reprogramming adult cells to an embryonic state to produce induced pluripotent stem (iPS) cells. First reported in 2006, the technique does not involve eggs, cloning or destruction of embryos4. “Honestly, the most surprising thing [about this paper] is that somebody is still doing human [SCNT] in the era of iPS cells,” says Miodrag Stojkovic, who studies iPS cells for regenerative medicine and runs a fertility clinic in Leskovac, Serbia. 
   
   But Stojkovic, like others, awaits the results of head-to-head comparisons between iPS and SCNT cells. Some research has shown that iPS cells are not completely reprogrammed and that stem cells derived from SCNT are more like embryonic stem cells derived from in vitro fertilization. Mitalipov and Tachibana are now conducting a study to compare iPS cells and SCNT cells derived from the same donor cell. “These results,” says Daley, “will be fascinating.”
target: – Scientists have made a long-sought—and controversial—breakthrough: They created stem cells from cloned human embryos for the first time, reports AP. In theory, the development by researchers at Oregon Health & Science University means that doctors might someday be able to grow tissue from an ailing patient's own DNA, thus reducing the chance of rejection in a transplant. Commonly cited examples are growing brain tissue to help a patient with Parkinson's disease, or pancreatic tissue to help diabetics. It's "one landmark step in a very long journey," says an expert at Children's Hospital Boston who wasn't involved with the work. The Oregon scientists say they don't think the embryos used in their process could develop into babies, reports NBC News, but the procedure is nonetheless controversial because it requires that the embryos be destroyed. Nature notes that competing technology in the last decade has made the push toward embryonic stem cells less intensive, but adds that the new paper in Cell is sure to reignite the debate. The scientists used eggs from donors, and it took six years to replicate the success they had with monkey embryos. They chalked it up to a series of small revisions over the years instead of a single aha! moment.