In 2001, President George W. Bush issued an executive order banning federal funding for new sources of stem cells developed from preimplantation human embryos. The action stalled research and discouraged scientists.
Five years later, a Kyoto University scientist, Shinya Yamanaka, and his graduate student, Kazutoshi Takahashi, re-energized the field by devising a technique to “reprogram” any adult cell, such as a skin cell, and coax it back to its earliest “pluripotent” stage. From there it can become any type of cell, from a heart muscle cell to a neuron.