The Obama administration can continue using federal tax dollars to fund human embryonic stem cell research, a U.S. appeals court ruled on Friday, overturning a judge's decision and handing a victory to the White House.
Here are some facts about human embryonic stem cells:
* Stem cells are the body's master cells, the source of all cells and tissue, including brain, blood, heart, bones and muscles.
* Embryonic stem cells come from days-old embryos and can produce any type of cell in the body.
* Scientists generally harvest embryonic stem cells from embryos left over after in-vitro fertilization attempts at fertility clinics. They can also be produced using cloning technology.
* Scientists hope to harness the transformational qualities of stem cells to treat a variety of diseases, including injuries, cancer and diabetes.
* The issue has been controversial because some people believe the destruction of any human embryo is wrong.
* U.S. legislation called the Dickey-Wicker Amendment forbids the use of federal funds for the creation or destruction of human embryos for research.
* Then-President George W. Bush restricted the use of federal funds to only a few batches of already existing human embryonic stem cells in 2001. President Barack Obama lifted the restriction in 2009 and asked the National Institutes of Health to decide which embryonic stem cells could be used in federally funded research.
* A federal judge in August enjoined the NIH from paying for human embryonic stem cell research after a lawsuit by two researchers who said the Obama administration's funding of the work violated Dickey-Wicker and took money away from other types of stem cell research.
* A U.S. appeals court allowed federal funding to continue in September pending the outcome of the case.
* States such as California, New York, Connecticut, Maryland, Illinois, Massachusetts and New Jersey acted on their own to fund this research during the years of the Bush restrictions. Institutions such as Harvard University also set up separate operations to pursue the research using private money.
* Advanced Cell Technology and Geron Corp are the only two U.S. companies in advanced stages of testing human embryonic stem cells.
* Many other companies are pursuing aspects of stem cell research including Athersys Inc, NeuralStem, Aastrom Biosciences Inc, Stemcells Inc, Reneuron Group Plc, Osiris Therapeutics Inc, Neostem Inc, Cytori Therapeutics Inc, iZumi Bio Inc and International Stem Cell Corp.
* Researchers have discovered how to make embryonic-like cells from ordinary cells, called induced pluripotent stem cells. Researchers can also transform one cell type directly into another cell type. Opponents of embryonic stem cell research say research can focus on this field, but most experts agree all approaches must be pursued.
(Editing by Eric Beech)