Institute for Stem Cell Research
In 2005, scientists in California reported that injecting human neural stem cells appeared to repair spinal cords in mice.
In 2005, scientists in California reported that injecting human neural stem cells appeared to repair spinal cords in mice. Institute for Stem Cell Research
Chung Sung-Jun/Getty Images
South Korean stem-cell scientist Hwang Woo Suk speaks during a news conference in Seoul, Jan. 12, 2006. A paper his team published in the journal Science, claiming an embryonic stem-cell line was made from a cloned human embryo, was discredited.
South Korean stem-cell scientist Hwang Woo Suk speaks during a news conference in Seoul, Jan. 12, 2006. A paper his team published in the journal Science, claiming an embryonic stem-cell line was made from a cloned human embryo, was discredited. Chung Sung-Jun/Getty Images
The first embryonic stem cells were isolated in mice in 1981. But it wasn't until 1998 that researchers managed to derive stem cells from human embryos. That kicked into full gear an ethical debate that continues to this day. Here's a look at key moments in the controversy so far:
1981: Embryonic stem cells are first isolated in mice by two groups — Gail Martin at the University of California, San Francisco, and Martin Evans, then with the University of Cambridge (he's now at the University of Cardiff).
November 1995: 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.
Nov. 5, 1998: Researchers at the University of Wisconsin and Johns Hopkins University report isolating human embryonic stem cells. The cells have the potential to become any type of cell in the body and might one day be used to replace damaged or cancerous cells. But the process is controversial: One team derived their stem cells from the tissue of aborted fetuses; the other from embryos created in the laboratory for couples seeking to get pregnant by in vitro fertilization. (MORE: 'Scientists Report Breakthrough in Embryonic Stem Cells')
Aug. 23, 2000: The National Institutes of Health issue guidelines that allow federal funding of embryonic stem-cell research. Former President Bill Clinton supports the guidelines.
February 2001: 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.
July 18, 2001: Sen. Bill Frist (R-TN) and Sen. Orrin Hatch (R-UT), a vocal abortion opponent, call for limited federal funding for stem-cell research.
July 29, 2001: House Speaker Dennis Hastert (R-IL) and other Republican House leaders come out in opposition to federal funding for research.
Aug. 9, 2001: President Bush announces his decision to limit funding to a few dozen lines of embryonic stem cells in existence at that date. Many of the approved lines later prove to be contaminated, and some contain genetic mutations, making them unsuitable for research. (MORE: 'Bush Limits Funding for Stem-Cell Research')
Nov. 25, 2001: Scientists at Advanced Cell Technology in Massachusetts claim to have cloned a human embryo. However, the evidence proves controversial and not conclusive.
Feb. 12, 2004: South Korean scientists announce the world's first successfully cloned human embryo. Unlike other past cloning claims, the scientists report their work in a prestigious, peer-reviewed journal, Science. The embryos were cloned not for reproductive purposes but as a source of stem cells. The news reopens the contentious 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. But critics argue that any form of cloning is morally repugnant and should be banned. (MORE: 'Scientists Succeed in Cloning Human Embryo')
June 25, 2004: New Jersey legislators pass a state 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. (MORE: 'New Jersey to Fund State Research on Stem Cells')
Nov. 2, 2004: 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.
May 19, 2005: The same South Korean researchers who reported cloning a human embryo in 2004 announce another milestone: They say 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 published in Science. (MORE: 'Researchers Report Advance in Stem Cell Production')
May 24, 2005: The House passes a bill that would ease President Bush's restrictions on federal funding for stem-cell research.
May 26, 2005: 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.
May 31, 2005: Connecticut approves $100 million in funding for adult and embryonic stem-cell research over the next 10 years.
July 13, 2005: 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.
June 15, 2005: 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.
July 29, 2005: In defiance of President Bush, Senate Majority Leader Bill Frist (R-TN) announces his support of legislation to ease federal funding restrictions for stem-cell research.
Sept. 19, 2005: 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. (MORE: 'Research Finds Stem Cells Aid in Spinal Cord Repair')
Sept. 21, 2005: 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.
Nov. 11, 2005: University of Pittsburgh researcher Gerald Schatten alerts editors at the journal Science that there may have been ethical lapses in a landmark cloning paper published in February 2004. In that paper, South Korean scientists claimed they had made an embryonic stem-cell line from a cloned human embryo. Schatten alleged 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 same group, a paper on which Schatten was senior author. In that paper, Hwang et. al. claimed to have made 11 cloned stem-cell lines. At the same time, Schatten severs his collaboration with the South Korean scientists.
Dec. 15, 2005: 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. (MORE: 'Top Stem-Cell Researcher Resigns After Ethical Lapse')
Dec. 16, 2005: 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 New Jersey.
Dec. 29, 2005: The Seoul National University investigation concludes all of the data was fabricated in the 2005 paper that Hwang's team published in Science. (MORE: 'Seoul University Debunks Stem-Cell Paper')
Jan. 10, 2006: The Seoul National University investigation concludes that the landmark 2004 paper was fabricated as well. Two days later, Science formally retracts both Hwang papers. (MORE: 'Earlier Work by S. Korean Scientist Also Fraudulent')
April 6, 2006: Gov. Robert Ehrlich signs the Maryland Stem Cell Research Act, which allocates $15 million for embryonic stem-cell research grants.
May 12, 2006: South Korean scientist Hwang Woo-suk is charged with fraud, embezzlement and violating the country's laws on bioethics. He faces up to 13 years in prison. In 2004, Hwang and his research team claimed they had created the world's first cloned embryos and extracted stem cells from them. An investigation concluded the research was fabricated.
July 2006: The Senate considers a bill that expands federal funding of embryonic stem-cell research. The House passed its version of the bill in 2005.
July 19, 2006: President Bush vetoes the bill — the first use of his veto power in his presidency. (MORE: 'Bush Vetoes Bill to Expand Stem-Cell Research')
Aug. 23, 2006: Scientists unveil a new technique they claim could break the political deadlock over human embryonic stem cells. Researchers with the company Advanced Cell Technology 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 ccould then be used to derive embryonic stem cells. (MORE: 'Firm Creates Stem Cells Without Hurting Embryos')
Nov. 7, 2006: 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 in the state. (MORE: 'Missouri Backs Stem Cells')
Jan. 7, 2006: 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.
Jan. 11, 2007: The House of Representatives is expected to pass a bill that would expand federal funding for embryonic stem-cell research, but the bill won't carry enough votes to override a threatened presidential veto. Both the House and the Senate passed the same legislation last year, with President Bush vetoing the bill.
Feb. 28, 2007: 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.
March 16, 2007: 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.
April 11, 2007: 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.
May 30, 2007: California Gov. Arnold Schwarzenegger announces an agreement between the University of California at Berkeley and Canada's International Regulome Consortium to coordinate stem-cell research at both institutions. The Ontario Institute of Cancer Research donates the first $30 million to fund a Cancer Stem Cell Consortium to advance work on potential cancer treatments.
June 6, 2007: 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 University, scientists make it possible to clone mice from previously fertilized eggs.
June 7, 2007: With a vote of 247 to 176, the House grants the final congressional approval for legislation to ease restrictions on federally funded embryonic stem-cell research. The bill would authorize federal support for research on stem cells from spare embryos that fertility clinics would otherwise discard. But the House is still 35 votes short of what it needs to override a presidential veto.
June 20, 2007: President Bush vetoes legislation that would have eased restraints on stem-cell research. This marks the second time the president has used his veto power against federally funded embryonic stem-cell research. The president also issues an executive order encouraging scientists to derive new methods to obtain stem cells without harming human embryos.
Nov. 14, 2007: Scientists for the first time successfully clone embryos from the cells of an adult monkey and derive stem cells from those cloned embryos. The Oregon National Primate Research Center researchers report their work in the journal Nature.
Nov. 20, 2007: Two independent teams of scientists report on a method for making human embryonic stem cells without destroying a human embryo.
By adding a cocktail of four genetic factors to run-of-the-mill human skin cells, two scientific teams, one in Japan and one in America, have been able to isolate cells that behave just like embryonic stem cells. The researchers caution there are many steps before these cells are useful for human therapies. But the work is being hailed by others in the field as a critical step forward, both scientifically and ethically.
The research appears in the journals Cell and Science.
Reporting by Maria Godoy, Joe Palca and Beth Novey.