"... embryonic stem cells were a researcher's dream. Now they're a political hot potato."
Frederic Golden, commentator
Stem cells are cells that have the ability to differentiate into a diverse range of cell types, creating the potential for the cells to be used to grow replacement tissues. American developmental biologist James Thomson (b. 1958), from the University of Wisconsin School of Medicine, won the race to isolate and culture human embryonic stem cells. On November 6, 1998, the journal Science published the results of Thomson's research, describing how he used embryos from fertility clinics (donated by couples who no-longer needed them), and developed ways to extract stem cells and keep them reproducing indefinitely.
With the ability to develop into any one of the 220 cell types in the body, stem cells hold great promise for treating a host of debilitating illnesses, including diabetes, leukemia, Parkinson's disease, heart disease, and spinal cord injury. They also provide scientists with models of human disease and new ways of testing drugs more effectively in living organisms. But for all the hopes invested, progress has been slow. It has not helped that stem cell research has been steeped in controversy, with different groups questioning the ethics of harvesting stem cells from human embryos.
In 2007 Thomson and Shinya Yamanaka, from Kyoto University, Japan, both independently found a way to turn ordinary human skin cells into stem cells. Both groups used just four genes to reprogram human skin cells. Their work is being heralded as an opportunity to overcome problems including the shortage of human embryonic stem cells and restrictions on U.S. federal funding for research.
