Stem Cell Debate
Researchers were first able to derive embryonic stem cells from human embryos in 1998. That scientific advance set off an ethical debate that continues to this day.
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Embryonic stem cells are first isolated in mice.
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Researchers at the University of Wisconsin isolate the first embryonic stem cells in primates — rhesus macaque monkeys. The research shows it's possible to derive embryonic stem cells from primates, including humans.
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Researchers at the University of Wisconsin and Johns Hopkins University isolate the first human embryonic stem cells. The cells have the potential to become any type of cell in the body and could potentially be used to replace damaged or cancerous cells. But the process is controversial because it requires destroying human embryos.
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The National Institutes of Health issue guidelines that allow federal funding of embryonic stem cell research. Former President Bill Clinton supports the guidelines.
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The month after taking office, President George W. Bush requests a review of the NIH funding guidelines and puts a hold on federal funds for stem cell research.
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Sen. Bill Frist, R-Tenn., and Sen. Orrin Hatch, R-Utah, a vocal abortion opponent, call for limited federal funding for stem cell research.
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House Speaker Dennis Hastert, R-Ill., and other Republican House leaders come out in opposition to federal funding for research.
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President Bush declares federal funding will go to research only select stem cell lines derived from destroyed embryos left over at fertility clinics. States retain the ability to appropriate money for research or to restrict it. Many of the approved lines later prove to be contaminated, and some contain genetic mutations, making them unsuitable for research.
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Scientists in Massachusetts claim to have cloned a human embryo. However, the evidence proves controversial and not conclusive.
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South Korean scientists announce the world's first successfully cloned human embryo. Unlike other past cloning claims, the scientists report their work in the prestigious, peer-reviewed journal, Science. The news reopens the debate over somatic-cell nuclear transfer, which is sometimes referred to as therapeutic cloning. Scientists say cloning offers a unique way to produce cells that may someday be used to treat diseases. Critics argue that any form of cloning is morally repugnant and should be banned.
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New Jersey legislators pass a budget that includes $9.5 million for a newly chartered Stem Cell Institute of New Jersey. The move makes New Jersey the first state to fund research on stem cells, including those derived from human embryos.
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California voters approve Proposition 71, which authorizes the state to spend $3 billion on embryonic stem cell research over 10 years. The measure is a response to federal funding restrictions put into place in 2001. It puts California ahead of the federal government and many other nations in promoting the research.
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The same South Korean researchers who reported cloning a human embryo in 2004 announce another milestone: claiming they've created a streamlined process that uses far fewer human eggs to produce usable embryonic stem cells — a major step toward mass production. Their work is again published in Science.
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New Jersey's governor announces the state will fund a $150 million stem cell research center and promises to champion a ballot initiative to allocate another $230 million.
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The House passes a bill that would ease President Bush's restrictions on federal funding for stem cell research.
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A version of the bill passed in the House is introduced in the Senate. Among Senate sponsors of the bill are two prominent Republicans, Sen. Arlen Specter of Pennsylvania and Sen. Orrin Hatch of Utah. Their support comes despite President Bush's promise to veto any legislation lifting the restrictions on funding he put in place on Aug. 9, 2001.
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Connecticut approves $100 million in funding for adult and embryonic stem cell research over the next 10 years.
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Connecticut Gov. M. Jodi Rell signs a public act that permits stem cell research and bans human cloning. The act appropriates $20 million for conducting embryonic or human adult stem cell research.
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Bypassing the Illinois state legislature, Democratic Gov. Rod Blagojevich creates a stem cell research institute by executive order. The institute will be funded through a line item in the state budget that gives the Public Health Department $10 million to fund research.
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Senate Majority Leader Bill Frist, R-Tenn., announces his support of an effort to loosen President Bush's restrictions on stem cell research, putting him at odds with the administration.
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Scientists in California report that injecting human neural stem cells appeared to repair spinal cords in mice. The therapy helped partially paralyzed mice walk again.
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Advocates of embryonic stem cell research in Florida propose a ballot initiative that would give $200 million in state funds toward the research over the next decade. Two days later, opponents of the science file a petition to amend Florida's state constitution to ban state funding for embryonic stem cell research.
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A University of Pittsburgh researcher alerts editors at the journal Science that there may have been ethical lapses in a landmark cloning paper published by South Korean scientists in February 2004. Gerald Schatten, a senior author of the paper, alleges that some of the egg donors in that study had been paid, and some were junior colleagues of the lead author, Hwang Woo Suk. Schatten also says there were minor technical errors in one of the tables in a 2005 paper by the group. Schatten severs his collaboration with the South Korean scientists.
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Hwang admits that there are serious errors in his 2005 paper in Science and asks the journal to retract it. The admission comes three weeks after Hwang apologized for ethical lapses and stepped down as head of the stem cell program at Seoul National University.
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New Jersey becomes the first state to finance human embryonic stem cell research. The state's Commission on Science and Technology awards $5 million to research teams throughout the state.
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A Seoul National University investigation concludes all of the data in the 2005 paper that Hwang's team published in Science was fabricated.
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The Seoul National University investigation concludes that the landmark 2004 paper was fabricated as well. Two days later, Science formally retracts both Hwang papers.
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Gov. Robert Ehrlich signs the Maryland Stem Cell Research Act, allocating $15 million for embryonic stem-cell research grants.
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Hwang Woo-suk is charged with fraud, embezzlement and violating the South Korea's laws on bioethics. He faced up to 13 years in prison.
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President Bush, exercising his veto power for the first time, vetoes a bill that expands federal funding of embryonic stem cell research.
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Scientists unveil a new technique they claim could break the political deadlock over human embryonic stem cells. Researchers say it's possible to remove a cell from an embryo without harming the embryo and then grow the cell in a lab dish. That single cell could then be used to derive embryonic stem cells.
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Missouri voters back a constitutional amendment that safeguards embryonic stem cell research in the state. Missouri's legislature had been trying to ban such research.
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Researchers at Wake Forest University and Harvard University report that stem cells drawn from amniotic fluid donated by pregnant women hold much the same promise as embryonic stem cells. They reported they were able to extract the stem cells from the fluid, which cushions babies in the womb, without harm to mother or fetus and turn their discovery into several different tissue cell types, including brain, liver and bone.
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Iowa's Gov. Chet Culver signs legislation easing limits on types of stem cell research in Iowa. The new legislation allows medical researchers to create embryonic stem cells through cloning. While allowing for further research, it prohibits reproductive cloning of humans.
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After approving nearly $45 million for embryonic stem cell research in February 2007, California's stem cell agency authorizes another $75.7 million to fund established scientists at 12 non-profit and academic institutions.
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The Senate passes a bill that would expand federal funding for embryonic stem cell research. The bill passes 63-34, just shy of the two-thirds majority needed to protect the legislation from President Bush's promised veto.
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Researchers at Whitehead Institute in Massachusetts succeed in modifying a skin cell so that it behaves like an embryonic stem cell. This is thought to ease some ethical concerns that cloning embryonic stem cells requires the destruction of a human embryo. At Harvard, scientists make it possible to clone mice from previously fertilized eggs.
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Voting 247 to 176, the House approves final legislation to ease restrictions on federally funded embryonic stem cell research. The bill authorizes federal support for research on stem cells from spare embryos that fertility clinics would otherwise discard. The House is still 35 votes short of what it needs to override a presidential veto.
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President Bush vetoes the legislation easing restraints on stem cell research. This is the president's second veto of federally funded embryonic stem cell research legislation. To blunt criticism, Mr. Bush issues an executive order directing the Health and Human Services Department to promote research into cells that — like human embryonic stem cells — also hold the potential of regenerating into different types of cells that might be used to battle disease.
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President Barack Obama signs an executive order reversing restrictions on federal funding of embryonic stem cell research. The long-expected move is likely to stir up not only the promise of scientific breakthrough but also the controversy over where government crosses a moral line.
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Credits:
CBS/AP/NPR
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