Embryonic stem cells, with their unique power to differentiate into every type of cell in the human body, have been hailed as the source of possible cures for everything from heart disease to Parkinson's but reviled by antiabortion activists, who oppose harvesting the cells from surplus frozen embryos. When the U.S. government decided in 2001 to deny funding for research that uses embryonic cells derived after August 9, 2001, observers predicted a brain drain of U.S. researchers to Europe.

But European countries are adopting their own restrictions, in some cases tougher than those in the U.S. The resulting patchwork-combined with low biotechnology funding-has hamstrung European embryonic-stem-cell research, says Martyn Postle, director of Cambridge Healthcare and Biotech, a consultancy in Cambridge, England. Worse, he adds, is legislation in the European Parliament-the lawmaking body of the European Union (which includes most European countries; nonmembers include Norway, Switzerland, and Iceland) that could outlaw all embryonic-stem-cell research in the EU. Such a ban would have to be enforced separately in each country. In short, the European research climate is not universally favorable.