printable versionTwo steps forward, one step back
July 9, 1981: Researchers at the University of Cambridge develop the first in-vitro embryonic stem cell lines from mice.
July 1, 1988: Stanford's Irving Weissman is the first to purify and characterize blood-forming stem cells from mice. He later isolates the cells in humans.
Aug. 15, 1995: University of Wisconsin scientists isolate the first embryonic stem cell line in primates.
Nov. 6, 1998: The first human embryonic stem cells are isolated and cultured at the University of Wisconsin.
Aug. 23, 2000: With support from President Bill Clinton, the National Institutes of Health announces that it will fund medical research using human embryonic cells. It also issues funding guidelines.
Jan. 26, 2001: President George W. Bush states that he has ethical concerns about the way embryonic stem cells are derived. The following month, 80 U.S. Nobel laureates send a letter urging Bush not to change the NIH funding guidelines.
July 31, 2001: By a vote of 265-162, the U.S. House of Representatives passes a bill to outlaw the "cloning" of human beings to create stem cells for research. The bill, which would also ban the importation of any medical treatments created abroad from cloned human embryonic cells, stalls in the Senate.
Aug. 9, 2001: Bush makes his landmark announcement that federal grants may only be used to conduct studies on stem cells already harvested from embryos. He prohibits federal funding of research that involves the creation or destruction of additional embryos.
Sept. 11, 2001: Scientists at the University of Wisconsin demonstrate that human embryonic stem cells can be transformed into blood precursor cells.
Nov. 25, 2001: Using somatic cell nuclear transfer, Advanced Cell Technology in Massachusetts performs the first "cloning" of human embryos.
Dec. 10, 2002: Stanford launches its Institute for Cancer/Stem Cell Biology and Medicine (later renamed the Stanford Institute for Stem Cell Biology and Regenerative Medicine), a multidisciplinary effort to develop novel treatments for cancer and other diseases.
Feb. 27, 2003: By a vote of 241-155, the House again passes a bill to outlaw the "cloning" of human beings. The bill dies in the Senate.
Feb. 12, 2004: South Korean researchers claim to have derived human stem cells from cloned human embryos. The claim is later determined to be fraudulent, and a paper in Science is retracted.
March 3, 2004: The Washington Post reports that only about one-quarter of the approved stem cell lines are likely to be available or useful for research. The next month, some 200 members of Congress ask Bush to expand his stem cell policy.
Nov. 3, 2004: Fifty-nine percent of Californians vote yes on Proposition 71, a ballot initiative to provide $3 billion in funding for stem cell research over 10 years and to create the California Institute for Regenerative Medicine.
Feb. 22, 2005: Three public-interest groups file lawsuits to invalidate the Proposition 71-created California Institute for Re generative Medicine.
May 24, 2005: Despite a veto threat from Bush, the House votes 238-194 in favor of a bill to ease the restrictions by allowing federal funding for research on stem cells from embryos that would otherwise be discarded by fertility clinics.
April 10, 2006: Stanford receives $1.2 million from the California Institute for Regenerative Medicine to train 16 stem cell researchers.
July 18, 2006: By a vote of 63-37, the Senate approves the 2005 House bill to loosen restrictions on stem cell research.
July 19, 2006: Bush vetoes the stem cell legislation. A USA Today/Gallup Poll shows that only 36 percent of Americans approve of the veto.
July 20, 2006: California Gov. Arnold Schwarzenegger authorizes a $150 million loan to the state's stem cell institute, created by Prop. 71, until the legal challenge is resolved.