US stem-cell research needs a coherent set of rules, according to experts from the National Academy of Sciences. Every institution working with human embryonic stem cells should create a committee to oversee the research, says the panel, which also recommends that some experiments should be banned.

“We think it's very important that everyone who's doing this work is operating in the same spirit, and with the same conditions of transparency and care,” says bioethicist Jonathan Moreno of the University of Virginia in Charlottesville, who co-chaired the panel. At present, much research on human embryonic stem cells in the United States is funded from private sources, placing it largely beyond the reach of federal regulations.

In its 26 April report, the panel says that committees should conduct different levels of review for various stem-cell experiments, according to the ethical challenges they pose. “We decided to set up categories to give guidance as to how to think about these things,” says panel co-chair Richard Hynes, a cell biologist at the Massachusetts Institute of Technology in Cambridge.

For instance, to study cell development, some scientists want to inject human embryonic stem cells into other species' blastocysts — embryos just a few days old that consist of a hollow ball of cells (see Nature 431, 885; 2004). The panel argues that such proposals would require thorough review and that experiments with blastocysts from primates should be banned because of the danger that the ‘chimaera’ produced could develop to term. “Some things should not be done because they cross ethical lines,” says Hynes.

The panel wants at a local level what some other countries have on a national basis. Australia, Britain and Canada have set up national committees to regulate stem-cell research. And in 2002, Singapore's Bioethics Advisory Committee recommended that its government do the same.

In the absence of federal guidelines, it seems the panel's recommendations provide a reasonable blueprint. “I hope they can help us move forward and establish the field,” says Leonard Zon of the Children's Hospital Boston, current president of the International Society for Stem Cell Research.