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Enlarge Image Gene fix. Red cells in this slice of mouse liver are making a human protein called A1At. Credit: K. YUSA ET AL., NATURE (ADVANCED ONLINE EDITION) ©2011 MACMILLAN PUBLISHERS LTD. Researchers have taken a step toward showing how stem cells might one day be used to help patients born with a deadly liver disease. The researchers corrected a DNA spelling error in patient skin cells that had been converted into so-called induced pluripotent stem (iPS) cells, then coaxed the cells to form liver cells that seemed to function normally in mice. The approach is still a long...

Medical researchers' hopes of replacing politically fraught embryonic stem (ES) cells with stem cells derived from adult tissues have suffered a setback. Induced pluripotent stem (iPS) cells, created by turning back the developmental clock on adult tissues, and ES cells display similar gene-expression patterns, and both can produce any of the various tissues in the human body. But patterns of epigenetic changes — alterations that affect gene expression without changing the DNA sequence — tell a different story about iPS cells, a team led by Joseph Ecker, a molecular geneticist at the Salk Institute in La Jolla, California, reports online...

Stem cells made from mature cells and rewound to an embryonic-like state retain a distinct "memory" of their past that might limit their potential for therapeutic use, scientists reported Wednesday in the journal Nature. [...] They looked at 1.2 billion places in each genome where such chemical markers [epigenomes] exist. The analysis was unusually rigorous — and therefore unusually revealing, Ecker said. Earlier studies examined representative regions in the genome, rather than the whole thing. [...] For the most part, the contents of Ecker's metaphorical rooms looked alike. But when they zoomed in, inconsistencies emerged. In a side-by-side comparison of...

Enlarge Image New fate. Applying synthetic RNA for a muscle master-control gene turns embryonic cells into muscle cells. Credit: Warren et al., Cell Stem Cell, Advance Online Publication (2010) Four years ago, scientists took a major step toward overcoming the biggest ethical hurdle in stem cell research. Instead of using cells derived from embryos, researchers found a way to make adult cells behave as though they were embryonic. Simply inserting extra copies of four genes into these cells gave them the power to develop into almost any cell type in the body—a potential boon for studying and ultimately treating...

Japanese researchers coax soft, living tissue from inside extracted wisdom teeth into forming stem cells. Scientists have found a new and relatively accessible supply line for stem cells that can grow into any type of cell in the human body -- extracted teeth. Like cells from embryos, the soft living tissue from inside teeth can be induced to become what are known as pluripotent stem cells, which have the potential to form several different cell types. Unlike embryonic cells, which are extracted from days-old human embryos, generating stem cells from dental pulp is a relatively non-invasive and non-controversial process. Studies...

Key difference between reprogrammed adult mouse cells and embryonic stem cells discovered.Stem-cell researchers have puzzled over why reprogrammed cells taken from adult tissues are often slower to divide and much less robust than their embryo-derived counterparts.Now, a team has discovered the key genetic difference between embryonic and adult-derived stem cells in mice. If confirmed in humans, the finding could help clinicians to select only the heartiest stem cells for therapeutic applications and disease modelling.Induced pluripotent stem (iPS) cells are created by reprogramming adult cells, and outwardly seem indistinguishable from embryonic stem (ES) cells. Both cell types are pluripotent — they...

WASHINGTON (Reuters) – In a surprise result that can help in the understanding of both aging and cancer, researchers working with an engineered type of stem cell said they reversed the aging process in a rare genetic disease. The team at Children's Hospital Boston and the Harvard Stem Cell Institute were working with a new type of cell called induced pluripotent stem cells or iPS cells, which closely resemble embryonic stem cells but are made from ordinary skin cells. In this case, they wanted to study a rare, inherited premature aging disorder called dyskeratosis congenita. The blood marrow disorder resembles...

Nature Methods' Method of the Year 2009 goes to induced pluripotency for its potential for biological discovery. This series of articles—and the related video—showcase how induced pluripotency is coming into its own in 2009 as a tool for discovery in both basic and disease biology and explore the incredible impact this area promises to have in biological research. The Methods to Watch feature provides a glimpse of future Methods of the Year and the Reader's Choice shows methods nominated by readers and editors, and the votes that they received...

Abstract A brief overview of methods for reprogramming to induced pluripotency and of the properties of induced pluripotent stem cells. Introduction What is induced pluripotency? Pluripotency—the ability to make all cell types of the body—is a property possessed by a few cells in the early mammalian embryo, those belonging to the blastocyst inner cell mass. Embryonic stem (ES) cells are derived by in vitro culture of the inner cell mass and are also pluripotent. As the embryo develops, its cells become progressively more specialized and pluripotency is lost, although somatic tissues retain what are called multipotent cells (or adult stem...

Abstract Rapid progress with induced pluripotent stem cells is bringing scientists closer to understanding their strengths and weaknesses as embryonic stem cell stand-ins. Introduction In 2006, with formidable legal and technical obstacles keeping the promise of embryonic stem cells (ESCs) in check, Shinya Yamanaka's announcement was truly a scientific 'shot heard around the world'. He and his team at Kyoto University had reprogrammed adult mouse fibroblasts into so-called induced pluripotent stem cells (iPSCs)1, opening the stem cell field to legions of eager scientists and offering the promise of unprecedented capabilities for targeted disease research using stem cells derived directly from...

Monya Baker is Technology Editor at Nature and Nature Methods Correspondence to: Monya Baker1 e-mail: m.baker@us.nature.com Abstract Now that the generation of induced pluripotent stem cells is becoming routine, researchers can get on to the more exciting prospect of using the cells to make discoveries in disease and basic biology. Monya Baker reports. Introduction As Shinya Yamanaka finished the experiments that would win him the 2009 Lasker prize, a stem-cell fraud was prominent in his thoughts. In 2005, Woo Suk Hwang had rocketed to star status for reportedly developing a technique to generate human embryonic stem (ES) cells genetically matched...

Famous for its antioxidant properties and role in tissue repair, vitamin C is touted as beneficial for illnesses ranging from the common cold to cancer and perhaps even for slowing the aging process. Now, a study published online on December 24th by Cell Press in the journal Cell Stem Cell uncovers an unexpected new role for this natural compound: facilitating the generation of embryonic-like stem cells from adult cells. Over the past few years, we have learned that adult cells can be reprogrammed into cells with characteristics similar to embryonic stem cells by turning on a select set of genes....

Al Gore on board for $20M stem cell venture

Induced pluripotent stem cells could be a boon for regenerative medicine.REUTERS/Junying Yu/University of Wisconsin-Madison Given the right conditions, any adult cell can be coaxed into becoming stem-cell like, according to a team of researchers based in the United States. The team, led by Rudolf Jaenisch of the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, were also able to speed up the process, cutting the time required for cells to become stem-cell like by around half. The results are good news for those battling to work out the complex biology of these cells, know as induced pluripotent stem (iPS) cells...

Live-cell fluorescence imaging identifies bona fide reprogrammed cells.Fluorescence imaging could help resolve whether iPS cells have been properly programmed.Alamy The next tools for reprogramming cells to an embryonic-like state might just be a camera and a set of fluorescently tagged antibodies. Researchers imaged more than a million human cells in vitro as they changed from skin tissue cells, known as fibroblasts, into colonies of induced pluripotent stem (iPS) cells. As expected, many similar-looking colonies appeared, but only very few consisted of fully reprogrammed iPS cells. After assessing which were which, researchers led by Thorsten Schlaeger and George Daley of the...

Alternative tissues shown to yield reprogrammed cells aplenty. Fat cells are more easily turned into iPS cells than fibroblasts.Punchstock Fat cells and pigment-producing skin cells can be reprogrammed into stem cells much faster and more efficiently than the skin cells that are usually used — suggesting large bellies and little black moles could provide much-needed material for deriving patient-specific stem cells."More than one type of adult somatic cell can serve as a target for reprogramming to a pluripotent state," says William Lowry, a stem-cell biologist at the University of California, Los Angeles, who was not involved in the research. "You...

Knocking out genes with a role in cancer prevention helps produce stem cells.Switching off the p53 pathway helped researchers to make stem-like cells.Wikimedia Commons Specialized adult cells made 'immortal' through the blockade of an antitumour pathway can be turned into stem-like cells quickly and efficiently.The findings — which should make it easier to generate patient-specific cells from any tissue type, including certain diseased cells that have proved difficult to transform — suggest that cellular reprogramming and cancer formation are inextricably linked.Since 2006, when Shinya Yamanaka of Japan's Kyoto University first created induced pluripotent stem (iPS) cells1 — which can develop...

The decision to offer New York women up to $10,000 to donate their eggs for stem cell research, payable by taxpayers, is "incredibly irresponsible and immoral," critics told FOXNews.com. New York's decision to offer women in the state up to $10,000 to donate their eggs for stem cell research, payable by taxpayers, is "incredibly irresponsible and immoral," critics told FOXNews.com. Wendy Wright, president of Concerned Women for America, said the move -- the first of its kind nationwide -- treats women as "commodities, almost like cows" and could lead to cash-strapped women in other states to partake in similar programs....

Technical feat shows that the different route to stem cells can indeed make a full mammal body. Two teams of Chinese researchers have created live mice from induced pluripotent stem (iPS) cells, answering a lingering question about the developmental potential of the cells. Since Shinya Yamanaka of Kyoto University in Japan created the first iPS cells1 in 2006, researchers have wondered whether they could generate an entire mammalian body from iPS cells, as they have from true embryonic stem cells. Experiments reported online this week in Nature 2 and in Cell Stem Cell 3 suggest that, at least for mice,...

Bioethics: The former director of the National Institutes of Health, once an enthusiast for embryonic stem cells, now says their future has "dimmed." So why is the administration bailing out research into such therapies while troubled states like California have committed billions?Aside from creating or saving a few research jobs, the administration's decision to federally fund embryonic stem cell research is, as we've noted, a bailout of bad science. It throws money at an avenue of research that time and adult stem cell progress have passed by. Applauding the administration's move was Sen. Arlen Specter, D-Pa., who echoed the claims...

In a proof-of-concept study, Mayo Clinic investigators have demonstrated that induced pluripotent stem (iPS) cells can be used to treat heart disease. iPS cells are stem cells converted from adult cells. In this study, the researchers reprogrammed ordinary fibroblasts, cells that contribute to scars such as those resulting from a heart attack, converting them into stem cells that fix heart damage caused by infarction. The findings appear in the current online issue of the journal Circulation. "This study establishes the real potential for using iPS cells in cardiac treatment," says Timothy Nelson, M.D., Ph.D., first author on the Mayo Clinic...

“The development of a human being begins with fertilization, a process by which the spermatozoon from the male and the oocyte from the female unite to give rise to a new organism, the zygote.” — Langman’s Medical Embryology, 7th edition, 1995 ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- For people who advocate the killing of embryonic human beings in the cause of biomedical research, the Holy Grail is an argument that would definitively establish that the human embryo, at least early in its development, is not a living human organism and therefore not a human being at all. The problem for these advocates is that all...

Less than two years ago, it looked like the ethical debate over human embryonic stem cells might be coming to an end. In November 2007, two research groups, one at the University of Wisconsin-Madison and another at Kyoto University in Japan, announced that they had succeeded in directly reprogramming human skin cells into stem cells. Earlier this year, Canadian and British researchers reported even better news. They have developed a new way to create such cells without using viruses, which pose a risk of producing tumors by damaging the transformed cells' genes. Yesterday, as many as 700 new stem cell...

Look to the retina as a likely site for the first success in stem-cell therapy. "The eye is the best place to test proof-of-concept for stem cell-based therapies," says Martin Friedlander of the Scripps Research Institute in La Jolla, California. Friedlander is co-founder of EyeCyte, also in La Jolla, whose investors include industry heavyweight Pfizer. Several laboratories are exploring stem-cell-derived transplants to delay or prevent blindness, and Pfizer recently put up funds for a project nearing human trials at University College London (UCL). Why the eye appeal? As organs go, it is easily accessible, somewhat protected from the immune system's...

Pirates can now trade in their peg-legs for real legs as scientists transform wood into bone.In a Royal Society of Chemistry journal Italian chemists show that ordinary wood can be turned into bone suitable for repairing damaged limbs.It brings a whole new meaning to the term "tree surgery".The microstructure of the wood is the perfect natural template for making bone as it allows growth of blood vessels and tissues, Anna Tampieri and colleagues report in the Journal of Materials Chemistry.By treating wood with a fairly simple set of chemical processes, the natural structure of the wood is retained.The wood is...

Enlarge ImageOn track. Colonies of genetically corrected cells taken from Fanconi anemia patients show red and yellow, markers associated with pluripotency. Credit: Juan Carlos Izpisúa Belmonte Two papers published this week appear to bring closer the day when embryonic-like stem cells can be used to treat human diseases. One study describes what scientists say is the safest method yet to produce these cells. The other reports success in using the cells to begin correcting a rare genetic disorder known as Fanconi anemia. Induced pluripotent stem (iPS) cells were first reported in 2006 by Shinya Yamanaka, a researcher at Kyoto...

Researchers have announced a breakthrough that could end the ethical debate surrounding stem-cell research. The groundbreaking technique would allow the conversion of adult cells into an embryonic-like state. Researchers have been competing in recent years to reach just such a discovery, which would allow them to perform their work without using the controversial embryonic stem cell lines. Scientists at the the Scripps Research Institute in San Diego believe the key to their success is converting the cells by using recombinant proteins, which eliminates subsequent genetic alterations that typically occur during later stages. "Instead of inserting the four genes into the...

Here’s Josh Brahm explaining this “Oprah” spot, in which Dr. Oz comes out against embryonic stem-cell research on scientific grounds (Warning: In it he handles, pokes and slices a real human brain).  Catholics remember sadly that Michael J. Fox was a huge proponent of clone-and-kill stem-cell research. How ironic that President Obama, who claims to want to “follow science” is funding precisely the kind of research that the medical community is abandoning. See Josh Brahm’s essay “9 Things the Media Messed Up About the Obama Stem Cell Story.”On the “Oprah” show, Dr. Mehmet Oz handles the brain of a 50-year-old...

A team of scientists has advanced stem cell research by finding a way to endow human skin cells with embryonic stem cell-like properties without inserting potentially problematic new genes into their DNA. The team was led by James A. Thomson, V.M.D., Ph.D., of the University of Wisconsin-Madison and supported in part by the National Institute of General Medical Sciences, a component of the National Institutes of Health. This is not the first time that scientists have endowed differentiated cells like skin cells with the capacity to develop into any of the roughly 220 types of cells in the body, a...

President Obama Also Kills Bush Executive Order for Adult Stem Cell Research by Steven ErteltLifeNews.com Editor March 10, 2009 Email RSSPrint Washington, DC (LifeNews.com) -- President Barack Obama did more on Monday than just force taxpayers to fund embryonic stem cell research that requires the destruction of human life. He also rescinded an executive order President Bush put into place funding adult stem cells and new research with iPS cells.Obama also rescinded Executive Order 13435 of June 20, 2007.President Bush put that order in place in June 2007 when he vetoed a Congressional measure that would have required embryonic...

Stem-cell advance could bring tailored treatments closer. Researchers are close to making safer stem cells.K. Woltjen et al. For the first time, specialized human cells have been transformed into a state similar to that seen in embryonic stem cells, without using viruses. The advance edges stem-cell biologists closer to clearing a barrier to using reprogrammed cells for therapies and drug screening."The field has been waiting for these papers," says Marie Csete, chief scientific officer at the California Institute for Regenerative Medicine in San Francisco. Embryonic stem cells are pluripotent — capable of generating all the body's specialized cell types —...

Scientists in Canada and Scotland have developed a virus-free method for generating embryonic-like stem cells that does not involve destroying embryos. Scientists say the new approach to growing so-called induced pluripotent stem (iPS) cells is an important step toward creating safe and reliable populations of cells for research and therapy. To create iPS cells, researchers turn back the clock in mature cells. They do this by reactivating dormant genes associated with pluripotency--a primitive state in which a cell has the potential to become any cell type in the body. Scientists first introduced iPS cells in 2006 and since then have...

WASHINGTON (Reuters) – Researchers said on Tuesday they had made a type of nerve cell out of ordinary skin cells in a new approach to stem cell research. They made motor neurons out of induced pluripotent stem cells, or iPS cells -- a type of cell made from ordinary skin cells that resembles human embryonic stem cells. Scientists hope that iPS cells might offer a substitute for embryonic stem cells and a short-cut to tailored medical therapy for a range of diseases. Motor neurons make muscles contract, and being able to make new motor neurons might help treat diseases such...

By inserting genes that turn back a cell's developmental clock, researchers are gaining insights into disease and the biology of how a cell decides its fate This year, scientists achieved a long-sought feat of cellular alchemy. They took skin cells from patients suffering from a variety of diseases and reprogrammed them into stem cells. The transformed cells grow and divide in the laboratory, giving researchers new tools to study the cellular processes that underlie the patients' diseases. The achievement could also be an important step on a long path to treating diseases with a patient's own cells. CREDIT: C. BICKEL/SCIENCE...

Since their discovery, stem cells have been hailed as the ultimate answer for crippling and incurable diseases such as Alzheimer's, Parkinson's and other conditions that leave vital organs like heart or nerves damaged beyond repair. Researchers from the University of Cambridge, under the leadership of Professor Austin Smith, Director of the Wellcome Trust Centre for Stem Cell Research at the University of Cambridge, recently published a paper detailing a new technology that can transform adult stem cells into induced pluripotent stem cells (iPS). This technique is able to reliably reprogram adult cells into iPS rapidly and can forego the need...

London, October 18 : An research team in the U.S. has made a major advance in repeatedly generating induced pluripotent stem (iPS) cells from the tiny number of keratinocytes attached to a single hair plucked from a human scalp. Juan Carlos Izpisua Belmonte, who led the study at the Salk Institute for Biological Studies, said that the breakthrough provided a practical and simple alternative for the generation of patient- and disease-specific stem cells, which had been hampered by the low efficiency of the reprogramming process. The researcher also said that the new process could spare patients invasive procedures to collect...

(UWIRE.com) This story was written by June Q. Wu, Harvard Crimson Researchers at the Harvard Stem Cell Institute are one step closer to achieving the ultimate promise of stem cell research creating tissues for every part of the body without the use of harmful viruses or cancer-causing genes. Harvard Medical School professor Konrad A. Hochedlinger and his colleagues reported last week on the Web site of the journal Science that they have created mouse induced pluripotent stem cells without permanently altering the genetic makeup of the cells. Their technique allows scientists to genetically manipulate a patients cells typically skin cells...

When people envision using human embryonic stem cells for “regenerative medicine,” they often talk about making neurons to treat Parkinson’s disease, cardiac cells to... --snip-- The idea faces other challenges beyond the huge volume of cells needed. The red cells produced from embryonic stem cells so far tend to resemble embryonic or fetal red cells more than adult ones. They tend to be larger and often contain nuclei, which could impede their passage through the body. And they have a different form of the globin molecule, which carries oxygen. --snip-- “The real test is in vivo,” said Dr. Thalia Papayannopoulou,...

Enlarge ImageDowns in a dish. Down syndrome is caused by an extra copy of chromosome 21 (circled). This is one of the diseases whose development researchers will now be able to study in the lab.Credit: I. Park et al., Disease-Specific Induced Pluripotent Stem Cells, Cell (2008) First a drop, then the deluge. Last week, scientists at Harvard University and Columbia University announced that they had proved the viability of a new way to study a disease--amyotrophic lateral sclerosis--by reprogramming cells from a patient to become pluripotent stem cells, which can then become any type of cell or tissue. Yesterday,...

Reprogrammed cells may offer insight into neurodegenerative disease. Skin cells from an elderly patient with amyotrophic lateral sclerosis (ALS) have been ‘reprogrammed’ to generate motor neurons, the type of nerve cells that die as the disease progresses. It is the first time that an induced pluripotent stem (iPS) cell line has been created from a patient with a genetic illness (J. T. Dimos et al. Science doi:10.1126/science.1158799; 2008). Like embryonic stem cells, iPS cells have the potential to develop into almost any of the body’s cell types and offer new disease insights. Patient-specific motor neurons, with a transcription factor called...

Until about a decade ago, there was only one way to make an embryo—the old-fashioned technique of combining an egg with a sperm. Then came Dolly the cloned sheep in 1996. Scottish scientists created her by injecting the nucleus of a breast cell from one sheep into the enucleated egg of another sheep. Dolly was essentially genetically identical to the donor of the breast cell nucleus. Since then researchers have used reproductive cloning to produce mice, cats, dogs, horses, cows, goats, pigs, and other mammals. As valuable as reproductive cloning is for producing livestock and research animals, most researchers were...

In what could signal a further shift in the global stem cell debate, lawmakers in an Australia state have rejected legislation allow the cloning of human embryos for research purposes. This week's vote in the Western Australia capital, Perth, is believed to be one of the first times the embryonic cloning issue has been considered by a legislature anywhere in the world since reports of a major research breakthrough last November prompted new questions about the need to use embryos at all. The issue will be under discussion on Capitol Hill again on Thursday, when a health subcommittee of the...

A study recently conducted at the Massachusetts Institute of Technology (MIT) showed for the first time that artificially created stem cells can be used to treat Parkinson’s disease. In another research project conducted at the Imperial College in London, scientists identified the source of nerve cells in the embryo. The findings of these research projects have led scientists to believe stem cells can be used in new therapies for Parkinson’s disease. Parkinson's disease (PD) is a degenerative neurological disorder that occurs when nerve cells (neurons) in an area of the brain that controls muscle movement die or become impaired. Currently,...

Fully mature, differentiated B cells can be reprogrammed to an embryonic-stem-cell-like state, without the use of an egg according to a study published in the April 18 issue of Cell. In previous research, induced pluripotent stem (IPS) cells have been created from fibroblasts, a specific type of skin cells that may differentiate into other types of skin cells. Because there is no way to tell if the fibroblasts were fully differentiated, the cells used in earlier experiments may have been less differentiated and therefore easier to convert to the embryonic-stem-cell-like state of IPS cells. B cells are immune cells that...

Scientists have taken skin cells from patients with eight different diseases and turned them into stem cells. The advance means scientists are moving closer to using stem cells from the patient themselves to treat disease. This would mean they could circumvent the ethical and practical problems of using embryonic stem cells, which has sparked much opposition. Researcher Dr Willy Lensch, of Harvard Medical School, said the technique had "incredible potential". He said it could help scientists understand the earliest stages of human genetic disease. We're looking at the perfect human brick - ethical, flexible and not rejected by the...

Nanotubes (above) were used to introduce a complex of proteins into testicular cells (stained, below).UNIDYMA Californian biotech company claims that it has used carbon nanotubes to ‘reprogramme’ adult human cells to an embryonic-like state — a breakthrough that removes the elevated risk of cancer that blights other techniques. But uncertainties about the cells, which have yet to be reported in a peer-reviewed journal, have left many sceptical. PRIMEGEN Last year, researchers led by Shinya Yamanaka of Kyoto University demonstrated that by using just four genes it was possible to reprogramme adult human skin cells to a stem-cell-like pluripotent state —...

Scientists have succeeded in using cells virtually identical to embryonic stem cells to "correct" sickle cell anemia in mice. The breakthrough was made possible by another advance announced barely two weeks ago that scientists had created "induced pluripotent stem" (iPS) cells from human skin cells. These iPS cells are very similar, although not exactly identical, to embryonic stem cells. The process bypasses the need to use embryos, and thus circumvents many of the ethical complications surrounding this type of research. The first research announcement had left open the question of whether iPS cells could actually be used for therapeutic purposes....

Corrected. Blood from mice treated with iPS cells (above) does not show the sickle-shaped cells present in untreated mice (top).Credit: J. Hanna et al., Science Skin cells reprogrammed to act like embryonic stem cells--a breakthrough first reported in human cells 2 weeks ago--are already showing promise as a therapeutic agent. In today's online edition of Science, researchers describe using induced pluripotent stem (iPS) cells to alleviate symptoms of sickle cell anemia in mice. The technique is not yet safe to try in people, but scientists say it is proof of principle that iPS cells could someday treat human disease. Induced...

Adult skin cells turned to pluripotent stem cells without a cancer-causing agent. Cell reprogramming taken one step further.National Institutes of Health Shinya Yamanaka of Kyoto University in Japan has followed the announcement last week of his startling success in turning human skin cells to embryo-like stem cells, by reporting that he has done the same without the cancer-causing agent used in his original recipe.The work brings scientists perhaps one step closer to the goal of being to use patient-matched stem cells for therapy.Yamanaka first demonstrated his method for 'reprogramming' cells in mice. Last year he showed that he could produce...

If the stem cell wars are indeed nearly over, no one will savor the peace more than James A. Thomson. Dr. Thomson’s laboratory at the University of Wisconsin was one of two that in 1998 plucked stem cells from human embryos for the first time, destroying the embryos in the process and touching off a divisive national debate.