A series of studies published this year have capitalised on the discovery of human stem cells - immature cells that can develop into any of the scores of specialised tissues of the body. As well as forcing scientists to re-evaluate the theories of how embryonic cells develop, the work offers a welter of "dazzling medical applications", Science says. "Stem cells may one day be used to treat human diseases in all sorts of ways, from repairing damaged nerves to growing new hearts and livers in the laboratory."
Stem cells can be isolated from the body and used in experiments to develop into different tissues. "Researchersfound stem cells from adults retain the youthful ability to become several different kinds of tissues; brain cells can become blood cells and cells from bone marrow can become liver."
Growing organs outside the body and transplanting stem cells from one individual to another raised new ethical concerns. "Thus, 1999 marks a turning point for this young field, as both science and society recognised - and wrestled with - our new-found power to manipulate a cell's destiny," Science says.
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