In a dramatic scientific first, two independent research teams announced in November 1998 that they had successfully isolated and grown a special kind of cell with the potential to develop into virtually any kind of human tissue.
The breakthrough was widely hailed as a pioneering event with vast potential for biological research. Many experts believe the cells, known as embryonic stem cells, could lead to new methods of drug discovery, improve scientific understanding of developmental biology, and advance the science of tissue and organ transplantation. But they also noted that many legal, ethical, and technical obstacles must be overcome before that potential can be realized.
Scientists had long sought to isolate the elusive cells but capturing them proved difficult. One reason for this difficulty is that embryonic stem cells only exist in their original, or undifferentiated, state momentarily, before turning into the various specialized cells of the body. The cells also need a highly specialized environment to keep them alive outside the body.
The research teams used two different methods to obtain the stem cells. One team, led by embryologist James A. Thomson at the University of Wisconsin in Madison, acquired the cells from immature human embryos, known as blastocysts. Their research was reported in the November 6 issue of the journal Science. Another team, led by geneticist John Gearhart at the Johns Hopkins School of Medicine in Baltimore, Maryland, derived their cells from fetuses that had been aborted early in pregnancy. Their findings were published in the November 10 issue of the Proceedings of the National Academy of Sciences.
Thomson and his colleagues isolated stem cells from the interior of blastocysts. The blastocysts, originally produced for the treatment of infertile couples, were not needed and donated for research.
The cells were then placed in a special culture to...