Verlinsky says he has already created 10 embryonic stem cell (ESC) lines using his new "stembrid" technique. Unlike therapeutic cloning, it uses existing ESCs instead of human eggs, and so would be much cheaper and easier. What's more, because no embryos are destroyed, it would bypass many ethical issues. "If it is as he said, it would be spectacular," says Jacques Cohen of Tyho-Galileo Research Laboratories, who has been investigating alternative sources of ESCs. But he and other experts say Verlinsky must do a lot more work to prove his claim.
While ESCs show great promise for treating many diseases, such as heart disease, diabetes and Parkinson's, non-matching ESCs would be rejected by patients' immune systems unless they take immunosuppressant drugs. This is why many stem cell researchers are trying to create ESCs that are identical to people's own cells.
Last year Woo Suk Hwang of Seoul National University claimed to have created an ESC line from a cloned human embryo for the first time. But there were doubts about the results. The technique requires an adult cell and an egg, and because in Hwang's experiment both came from the same person, it was difficult to prove the embryo really was cloned (New Scientist, 21 February 2004, p 6). The process was also very inefficient, taking 242 eggs to create just one ESC line.
Now Hwang has created 11 more ESC lines from cloned embryos in an impressive study that answers all the criticisms of his original study. He has also