Photos: History of stem cells Experts in the field of regenerative medicine believe one of the first areas of success when using stem cell-derived therapies will be the treatment of macular degeneration, which causes progressive loss of sight, and other retinal diseases. Click through the gallery to learn more about stem cell research. Hide Caption 1 of 16

Photos: History of stem cells In January 2014, researchers announced they had developed a new method of making stem cells: by placing skin cells in an acidic environment. But the researchers retracted their papers in July, citing "several critical errors" in their study data. Hide Caption 2 of 16

Photos: History of stem cells Stem cells have the potential to become many kinds of cells and can renew themselves through cell division. Scientists view stem cells as a possible gateway to curing many medical conditions, from Parkinson's disease to diabetes. Stem cells are viewed on computer here at UConn Health Center in 2010. Hide Caption 3 of 16

Photos: History of stem cells A closeup of a microscope slide taken in 2000 at the Reproductive Genetics Institute's Chicago laboratory shows transplanted stem cells taken from the umbilical cord blood of a baby named Adam Nash. Adam's sister Molly has a genetic disease called Fanconi anemia. Their parents wanted to have a child who could be a stem cell donor for Molly. Using in vitro fertilization, doctors created embryos and then tested them for the genetic disease. They chose one that did not have the disorder, which grew into baby Adam. Molly received a stem cell transplant from stem cells from Adam's umbilical cord. Both children are alive today. Hide Caption 4 of 16

Photos: History of stem cells In 1998, President Bill Clinton requested a National Bioethics Advisory Commission to study the question of stem cell research. Hide Caption 5 of 16

Photos: History of stem cells In 2000, the National Institutes of Health issued guidelines for the use of embryonic stem cells in research, specifying that scientists receiving federal funds could use only extra embryos that would otherwise be discarded. President Clinton approved federal funding for stem cell research, but Congress did not fund it. Above, a Cell Expansion System, which is used to grow cells, is seen during the 2010 World Stem Cell Summit in Detroit. Hide Caption 6 of 16

Photos: History of stem cells In August 2001, President George W. Bush announced that he would allow federal funding for about 60 existing stem cell lines created before this date. Above, a human stem cell colony, which is no more than 1 millimeter wide and comprises thousands of individual stem cells, grows on mouse embryonic fibroblast in a research laboratory in September 2001. Hide Caption 7 of 16

Photos: History of stem cells In 2005, Connecticut and Illinois designated state funds to support stem cell research in their states. Above, a woman works on stem cells at the University of Connecticut's Stem Cell Institute at the UConn Health Center in August 2010 in Farmington. Hide Caption 8 of 16

Photos: History of stem cells In March 2009, President Barack Obama signed an executive order that removed restrictions on embryonic stem cell research. His action overturned an order approved by President George W. Bush in August 2001 that barred the National Institutes of Health from funding research on embryonic stem cells beyond using 60 cell lines that existed at that time. Hide Caption 9 of 16

Photos: History of stem cells In November 2010, William Caldwell, CEO of Advanced Cell Technology, said the FDA had granted approval for his company to start a clinical trial using cells grown from human embryonic stem cells. The treatment would be for an inherited degenerative eye disease. Above, dozens of packages containing frozen embryonic stem cells remain in liquid nitrogen in a laboratory at the University of Sao Paulo's human genome research center in Sao Paulo, Brazil, in March 2008. Hide Caption 10 of 16

Photos: History of stem cells In May 2011, stem cell therapy in sports medicine was spotlighted after New York Yankees pitcher Bartolo Colon was revealed to have had fat and bone marrow stem cells injected into his injured elbow and shoulder while in the Dominican Republic. Hide Caption 11 of 16

Photos: History of stem cells In February 2012, early research published by scientists at Cedars-Sinai Medical Center and Johns Hopkins University showed that a patient's own stem cells can be used to regenerate heart tissue and help undo damage caused by a heart attack. It is the first instance of therapeutic regeneration. Above, fluid is removed from the knee of a patient to collect adult stem cells by at a clinic in Broomfield, Colorado. Hide Caption 12 of 16

Photos: History of stem cells In October 2012, Sir John Gurdon and Shinya Yamanaka were awarded the Nobel Prize for Physiology or Medicine for discovering how to make pluripotent stem cells. They both showed that cells could be reprogrammed after they had specialized. This changed scientists' understanding of how cells and organisms develop. Hide Caption 13 of 16

Photos: History of stem cells On May 16, 2013, scientists announced that they had, for the first time, produced embryos using skin cells and then used the embryos to make stem cell lines. This technique resembles what was used in cloning Dolly the sheep, but the earlier technique could not have led to a fully cloned human baby. A photo provided by the Oregon Health & Science University shows a stem cell colony produced from human skin cells. Hide Caption 14 of 16

Photos: History of stem cells On August 5, 2013, the world's first stem cell burger was cooked and eaten in London. The brainchild of Maastricht University's Mark Post, the burger was made of 20,000 small strands of meat grown from a cow's muscle cells, took three months to create and cost $330,000 to develop. Hide Caption 15 of 16